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Functional bread: Effect of inulin-type products addition on dough rheology and bread quality
Accepted Manuscript Functional bread: Effect of inulin-type products addition on dough rheology and bread quality Alexandrina Sirbu, Camelia Arghire PII:
S0733-5210(16)30217-X
DOI:
10.1016/j.jcs.2017.03.029
Reference:
YJCRS 2330
To appear in:
Journal of Cereal Science
Received Date: 8 December 2016 Revised Date:
11 March 2017
Accepted Date: 27 March 2017
Please cite this article as: Sirbu, A., Arghire, C., Functional bread: Effect of inulin-type products addition on dough rheology and bread quality, Journal of Cereal Science (2017), doi: 10.1016/j.jcs.2017.03.029. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Title: Functional Bread: Effect of Inulin-Type Products Addition on Dough Rheology and Bread Quality Authors: Alexandrina SIRBU1,2, Camelia ARGHIRE2
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Affiliations: Constantin Brancoveanu University, FMMAE Ramnicu Valcea, 39 Nicolae Balcescu Bld., Romania; cell
+40744993123; e-mail [email protected], [email protected] (Corresponding author) COPE Ltd., Conacul Cantacuzino-Pascanu, Costisa- Neamtz, Romania; e-mail [email protected]
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Key words: functional fibre and inulin; mixolab; rheological behaviour; half-white bread.
ACCEPTED MANUSCRIPT Abstract The concerns for a healthy diet in terms of the consumption of baked products as fibreenriched ones have been highlighted by increased consumers demand, food legislation and targeting manufacturers offer to healthy food. The objective of this study was to assess the effect of some inulin-type products added in bread-making aimed at producing functional
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bakery goods. In this purpose some physico-chemical characteristics and technological properties of the Romanian wheat flour half-white with addition of 5 %, 10 %, 15 % and 20 % inulin commercial products (% basis flour) were evaluated. Rheological behaviour was investigated using mixolab Chopin and baking tests for fibre-enriched products were
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performed. Changes of the rheological behaviour were noticed, in terms of a general
decreasing trend of dough machinability due to enzymatic reactions probably influenced by changing the ratio of the main compounds and their interactions. Overall the bread loaves
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characteristics mainly affected by inulin addition were the volume and crust colour. Results indicated that inulin potential as fibre enrichment in wheat bread is limited, 15 % Fibruline DS being a maximum percent to be used in bread-making of half-white flour, a dosage above being critically for dough rheological behaviour and the quality of high-fibre
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bread.
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1. Introduction
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1.1. Functional fibre for healthier baked products
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Nowadays consumers are more aware about healthy eating aimed at improving their quality of life and in this regard their main demands refer to food nutrients and their
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functionality (e.g. Euromonitor International (2013) through the Global Consumer Trends
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Survey showed that consumers look for “added vitamins or fibre” on foodstuffs labels).
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Naturally, the concerns for a healthy diet in terms of food consumption have been also
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highlighted by food legislation (e.g. Reg. EC No 1924/2006, including all amendments, has
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imposed specific provisions concerning the use of nutrition and health claims about foods
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through goods labelling). For gaining a competitive advantage on the market, bakery
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manufacturers tailored adequately their food commodities and producers have lined up the
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offer based on evolving consumers’ preferences. Consequently, trends within the bakery and
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pastry market focused on health and wellness products have followed double strategies based
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on either health or nutrition claims. A health claim refers to the statement about a relationship
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between food and health, whilst the nutrition claim concerns nutrients or ingredients that have
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a nutritional function or a physiological effect proved scientifically. In that way baking
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industry has started to develop a wide range of baked products, such as: vitamin-enriched,
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fortified with minerals, „high” protein, “low” sugar, “rich” fibre, “light” fat, „gluten-free” etc.
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On this point, many researches have paid attention to baked products with fibre addition, too.
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In order to study dietary fibre (DF), since the 1970s two requirements have had to be
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met, namely fibre definition and appropriate methods of analysis. It seems that the most
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debates referred to definition issues. For instance, in the period 2005-2013, USDA, Institute
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of Medicine (IOM), American Association of Cereal Chemists International (AACCI),
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European Commission and European Food Safety Authority (EFSA), other national
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Commissions as well as Codex Alimentarius Commission have had different approach on this
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topic. Although their agreed definitions bear many similarities, some important differences
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exist with regards to types/ chemical and functional issues. According with USDA (2005), the
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dietary fibre is defined as non-digestible carbohydrates and lignin that are intrinsic and intact
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in plants, whilst a functional fibre is defined as isolated, non-digestible carbohydrates that
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have been shown to have beneficial physiological effects in humans. Official definitions of
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dietary fibre that were expressed by European and Codex Alimentarius Commissions are
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quite different. Commission Directive 2008/100/EC amending Council Directive
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information to consumers lay down definition of „fibre” as „carbohydrate polymers with three
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or more monomeric units, which are neither digested nor absorbed in the human small
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intestine and belong to the following categories: -edible carbohydrate polymers naturally
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occurring in the food as consumed; -edible carbohydrate polymers which have been obtained
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from food raw material by physical, enzymatic or chemical means and which have a
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beneficial physiological effect demonstrated by generally accepted scientific evidence; -edible
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synthetic carbohydrate polymers which have a beneficial physiological effect demonstrated
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by generally accepted scientific evidence." Although Codex Alimentarius Commission tried
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to align dietary fibre definitions there are still a few items which differ from those introduced
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above (Howlett et al, 2010).
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Other debates have arisen concerning the fact that fibre should be traditionally consumed as plant material; some scientists have promoted the spiked fibre in the food matrix
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with emphasis mainly on edible aspects and physiological benefits of these carbohydrate
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polymers. At the moment it is acknowledged the role of both intrinsic and added fibre.
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However, regarding fibre’s definition, a mutual consensus appeared about the importance to
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prove the beneficial physiological effects of these kind of non-digestible carbohydrate
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polymers used. In fact majority provisions on definition of dietary fibre claims as mandatory
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the benefit to health to be demonstrated by generally accepted scientific evidence to
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competent authorities.
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Generally speaking, dietary fibre are classified based on their solubility in water. Thus, soluble DF are oligosaccharides, pectins, β–glucans, and galacto-manan gums alginate,
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psyllium fibre; and insoluble fibre are cellulose, hemicellulose, and lignin. According IOM
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(2001-cited in USDA, 2005) dietary fibre consist of plant non-starch polysaccharides (e.g.
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cellulose, pectin, gums, hemicellulose, β-glucans, as part of oat and wheat bran), plant
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carbohydrates that are not recovered by alcohol precipitation (e.g., inulin, oligosaccharides,
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and fructans), lignin, and some resistant starch. Potential functional fibre for food labelling
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include isolated, non-digestible plant (e.g., resistant starch, pectin, and gums), animal (e.g.,
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chitin and chitosan), or commercially produced (e.g. resistant starch, polydextrose, inulin, and
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indigestible dextrins) carbohydrates. As is depicted above, there is also other criteria used for
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dietary fibre classification, as chemical or botanical ones.
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It was shown that dietary or/and functional fibre have one or more beneficial
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physiological effects such as: decrease intestinal transit time; increase stool bulk; is digested
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through fermentation by colonic microflora; reduce blood total or/ and LDL cholesterol 2
ACCEPTED MANUSCRIPT levels; reduce post-prandial blood glucose, or reduce blood insulin levels. As Eastwood and
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Kritchevsky (2005) reviewed, the fibre acts in the digestive tract by changing either the nature
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of the contents of the gastrointestinal tract or how other chemicals and nutrients are absorbed.
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Beside the physiological effect of the fibre, their functionality has been studied in the etiology
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of diseases (cardiovascular and heart disease, colonic diverticulosis, obesity, cancer etc.) and
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epidemiology because of the evidence associating dietary fibre with reduced health risks.
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Although fibre are used in different diets for more than a century, a scientific holistic
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understanding in-depth in nutrition and medical trials is still in progress.
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A third pathway for research of the dietary fibre addresses straightly to food domain, and consists of the assessment of their functionality in food matrix through physical-chemical
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characteristics (e.g. water binding, rheological behaviour etc.) with relevant impact for
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technological performances and sensorial characteristics of the end-products that can be
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acceptable in terms of consumers preferences.
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Fibres vary in structure and functions and it seems that an optimal diet in fibre refers at
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the same time to the right amount of fibre and a suitable balance between them. For instance,
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a daily recommended intake as an adequate intake (AI) ranges from 21 to 38 g of fibre,
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depending on age and gender characteristics as well as referees (WHO/FAO, EFSA, UK Food
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Standards Agency etc.). Scientific literature shows that dietary fibre are required to be
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ingested for an obvious physiological effect at a minimum intake of 12 g/day, but some voice
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the opinion that an increase DF intake is necessary to be promoted for both prevention and
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management of disease. Nevertheless dietary fibre cannot be an essential part of the diet, but
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nowadays a healthy diet should include various fibre types. Also, the doses of fibre
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enrichment should be related with the types of bakery products (bread, biscuits, pastry,…) as
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well as with the food purposes (conventional food, functional ones and foods for specific
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groups – PARNUTS). According with food legislation (Regulation EC No 1924/2006) drawn
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up, nutritional claims regarding fibre content can be “high-fibre” for 6 g DF per 100 g or 3 g
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per 100 kcal or 20 % of daily reference value per serving, while a food as a source of fibre
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means the product contains at least 3 g of fibre per 100 g or at least 1,5 g of fibre per 100 kcal.
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1.2. Inulin fibre
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As it mentioned above, inulin type-fructans fulfil all five basic attributes of dietary fibre.
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Inulin, oligofructose and fructooligosaccharides (FOS) naturally occur in a large variety of
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edible plants as storage carbohydrates; but they are mainly industrial processed from chicory 3
ACCEPTED MANUSCRIPT and Jerusalem artichoke. They have a polydisperse carbohydrate composition consisting
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mainly, if not exclusively, of β-(2←1) fructosyl-fructose linked oligomeric carbohydrates
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with linear chains and polymers with a different polymerisation degree (DP) ranging from 3
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to 60 and, in general, with a terminal glucose unit (Roberfroid, 2007). Because of their β–
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(2←1) glycosidic linkages, inulin type-fructans have resistance to enzymatic digestion in the
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upper gastrointestinal tract; but are quantitatively fermented by the large bowel endogenous
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microbiota, being associated with a surely prebiotic effect and other health benefits, such as:
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laxation, normalization of blood lipid concentrations, attenuation of blood glucose responses
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(USDA, 2005), modulation of the composition of the intestinal microbiota and improvement
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of gut functions (Bosscher et al, 2009; Patel and Goyal, 2012), potential enhancement of
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calcium and magnesium absorption (Roberfroid, 2007).
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Inulin products may contribute to a well-balanced diet by increasing the fibre content and diversifying the fibre sources, with multiple functional beneficial effects on human health
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and nutrition. The recommended dose of inulin for its different physiological benefits varies
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between 10 g and 15 g. Nevertheless, it seems that the over-dosage lead to a malabsorption
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and digestive distress for some people. Also, the data on a potential allergenicity of inulin and
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oligofructose is quite limited. Regarding nutrition, beside its prebiotic role, inulin contains
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25–30% the food energy of sugar or other carbohydrates and 10–15% the food energy of fat,
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reason for which it has started to replace sugar, fat, and flour in different recipes of foodstuffs
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and nutritional supplements. Extensive research was done in order to characterise inulin
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behaviour in food matrix or assess its technological properties with a final purpose to be used
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as ingredient for obtaining functional food. The bakery products have been good vectors for
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prebiotic or high-fibre foodstuffs and have attracted interest for inulin, oligofructose and FOS
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enrichment aimed at obtaining either low-fat baked goods or carbohydrate substitution in
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dough matrix (Volpini-Rapina et al., 2012; Brasil et al., 2011; Zahn et al., 2010; Devereux et
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al., 2003; etc.). Different research teams have investigated whether inulin-enriched breads are
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feasible for bread-making in terms of dough behaviour, bread characteristics and consumers
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acceptance and many studies proved that inulin allows the developing of baked products with
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an acceptable or comparable sensorial quality of end-products related to regular ones
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(Filipovic et al., 2010; O’Brien et al., 2003; Wang et al., 2002). Although many investigations
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have been performed, new research needs become apparent in order to understand overall
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conditions and mechanisms that influence dough rheology and baking science.
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1.3. Rationale and research questions
138 The objective of this study refers to assessment of some inulin-type fructans products
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used in bread-making aimed at producing bakery goods for a better diet. By using different
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doses of inulin-type products up to a percent, which justifies a prebiotic claim, their effect on
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the properties of common wheat dough and bread was evaluated. Also in many previous
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studies they used inulin-type fructans with a degree of polimerization (DP) greater than 10
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because of their differences in solubility in comparison with those with DP < 10, but as we
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have already introduced above the arbitrary cut-off at DP=10 does not have a ground reason
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either analytically or physiologically (Howlett et al, 2010). In this respect we focus our
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research on addition of inulin-type fructans products with DP < 10 in dough and bread recipes.
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Investigations of other researchers focus on white and dark breads (e.g. Koryachkina et
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al., 2012; Brasil et al., 2011), reason for what the half-white flours have been chosen for our
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experimental. Another rationale of usage half-white wheat flour (type 800) is that inulin and
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oligofructose may affect the quality of big dark wheat breads (as shown Koryachkina et al.,
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2012). Although flours are made from common wheat, another interest of this study has been
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directed towards the assessment of Romanian grains harvested for commercial purpose. In this study the dough behaviour has been assessed mainly through mixolab method,
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whilst in the majority of previous studies the dough performances with addition of inulin type
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fibre were investigated by using other methodologies and equipment, such as farinograph,
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extensograph, alveograph and mixograph (as reviewed Foschia et al, 2013; Ktenioudaki and
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Gallagher, 2012; Morris and Morris, 2012).
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2. Experimental
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2.1. Materials and methods
As raw material, half-white commercial flour from Romanian common wheat (Triticum
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aestivum) was used. Samples were made on duplicate. Protein content, moisture content,
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falling number, ash content, wet gluten content, acidity, alveograph and mixolab data have
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been accomplished according to Romanian and international standard methods for flours and
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dough, as is shown in table 1. Overall results indicated an average to good quality of flour
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chosen like start material (see table 1).
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Table 1. Quality assessment of the flour used in experiments
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Assessment of flour quality, as raw material (F3) Characteristics Values Analysis method Moisture content, % 14.0 ISO 712:2009 Ash content, % 0.80 SR 90:2007 Protein content, % 11.8 SR 13013-3:1994 SR EN ISO 21415-1:2007 Wet gluten, % 28.8 Acidity, grd. 2.8 SR 90:2007 Falling number, s 305 ISO 3093:2010 Rheological behaviour of dough Alveograph method Mixolab method (according to SR EN ISO 27971:2008) ((according to ISO 17718:2013) Alveograph parameters Values Tenacity P, mm 67 Water absorption, % (base 14%) Extensibility L, mm 103 Maximum torque during mixing C1,Nm P/L ratio 0.65 Amplitude, Nm Energy/baking strength W 10-4J 185 Stability, min Index of swelling G, mm 22.6 Protein weakening based on mechanical work and temperature C2, Nm Elasticity index Ie, % 45.6 Starch gelatinisation C3, Nm Stability of starch gel formed C4, Nm Starch retrogradation during cooling stage C5, Nm α slope, Nm/min β slope, Nm/min γ slope, Nm/min
Values 58.1 1.12 0.07 7.38 0.45 1.73 1.66
2.50 -0.068 0.446 -0.026
In experimental we used as soluble fibre three kinds of chicory fructans produced by Cosucra (Belgium) and supplied by Enzymes & Derivates Romania, namely: Inulin Instant
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(inulin), Fibruline DS2 (inulin) and Fibrulose F97 (oligofructose). These are white powders
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with a neutral to light-sweet taste. Their characteristics are introduced in table 2.
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Table 2. Quality characteristics of chicory fructans used as soluble fibre in experiments Nutritional and biochemical characteristics Energy, kcal/kJ/100 g Dry matter (g/100 g) - in which reducing sugars Dietary fibre (g/100 g) - in which chicory fructans Carbohydrates-free/100 g Relative sweetening power, % Sweetening power DE, %
Inulin Instant
Fibrulose F97
Fibruline DS2
208/840 96 8.0 88.0 88.0 8.0 10 5-10
198/795 96 3.0 93.0 93.0 3.0 10 10-15
196/786 96 2.0 94.0 94.0 2.0 2 2-7
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DP: ≈10
DP≤10: 70±5% DP≤20: 94±5% DP>20: 5±5%
DP: <10
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2.2. Rheological performance
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181 The rheological behaviour of flours in terms of stretching properties of the dough gives
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information about the relationship between the force and deformation, and there was studied
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by using Alveograph and Mixolab devices. Through the Alveograph method the dough is
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submitted to biaxial deformation, while the dough prepared within Mixolab equipment is
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subjected to a dual mixing and temperature constraint. The Chopin Mixolab device allows
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characterisation of thermal and mechanical behaviour of flours, namely water absorption
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capacity and kneading stability, gelatinisation temperature, amylase activity and starch
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retrogradation.
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Rheological behaviour of dough by mixolab Chopin was assessed by using standard Mixolab software, with the specific protocol (ICC no. 173) (Rotational speed: 80 rpm; Target
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value 1.1 +/- 0.07 Nm; tank temperature 30˚C, heating rate 2 ˚C/min). As reference
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methodology, it was applied ISO 17718:2013 for determination of rheological behaviour as a
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function of mixing and temperature increase.
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2.3. Baking procedure
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Baking tests were performed based on recipe, which comprised the following
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ingredients: flour and chicory fructans products (see 2.1.), baking yeast - Saccharomyces
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cerevisiae (Pakmaya; supplier ROMPAK SRL Paşcani Romania), salt (commercial iodized
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salt), and water. Each raw material (of yeast, salt and water) had an appropriate quality for
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bread-making determined according with the standard methods of analysis (SR 13360 – 1995,
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STAS 985- 1979,..).
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Breads were made in triplicate and baking recipe consists of 1000 g flour, 30 g fresh
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baking yeast, 15 g salt, a quantity of water according with water absorbtion (i.e. 581 ml), and
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different doses of inulin-type products. In dough formulation the addition of chicory fructans
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was made as percentage, namely 5 %, 10 %, 15 % and 20 % (basis 100 g flour). Breads were
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obtained through a direct method.
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Regarding the bread-making, dough was prepared by mixing (7…10 min) until a developed and smooth dough was obtained (at 30 oC); then the bulk fermentation for 150 min
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at 30 oC was done prior to division in three parts, hand moulding and final proof for 50 min at
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a temperature of 30 oC with a relative humidity of 85 %. Dough pieces were baked for 30 min
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at 230 oC and after withdrawal from the oven were put into a place for cooling (1-2 h). Bread
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quality was evaluated afterwards.
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The loaf volume and physical properties (elasticity, porosity) of the breads were
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evaluated by means of the Romanian method for baking test performing (SR 91-2007). Loaf
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volume was measured by rapeseed displacement. Elasticity was assessed as crumb hardness at
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uniaxial compression test and porosity was determined as a total volume of hollows of a
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known volume of breadcrumb.
Statistical assay was computed by the software SPSS (v. 11.0) for Windows.
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3. Results and Discussion
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Preliminary research (unshown data) proved that the better choice for our experiments is Fibruline DS2. This product consists of the highest soluble fibre (%) and the lowest reducing
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sugars. Also it comes with lower energy intake in comparison with the other chicory fructans.
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However, its solubility is related with the chain length (DP<10). Further, the technological
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results with addition of 5 %, 10 %, 15 % and 20 % inulin - Fibruline DS2 (% basis flour) are
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introduced.
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3.1. Rheological evaluation
Rheological behaviour measured by using mixolab Chopin is expressed in figures 1 and
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2. Mixolab data for dough samples with 5 %, respectively 15 % Fibruline DS2 (DS2) added
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are introduced in figure no. 1, while in figure 2 the radial diagram made on Mixolab for a
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comparative assessment of rheological behaviour of dough in relation with all doses of inulin-
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type product used in experimental is done.
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a) 5 % DS2
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b) 15 % DS2
Figure 1. Mixolab data for dough with 5 % and 15 % Fibruline DS2 added
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Figure 2. Mixolab diagram for samples with Fibruline DS2 (5 %; 10 %; 15 %; 20 %)
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dough rheology and baking process at doses varied from 1 % to 10 % mainly, and more
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convenient or acceptable results were obtained for an inulin dose of 5-6 % (Park et al, 2016;
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Brasil et al., 2011; Peressini and Sensidoni, 2009; etc). But in our experiments the soluble
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fibre content was doubled and increased up to 20 % to be surely for its functional effect
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(complying with regulations requirements). For that reason, as is also shown in figure 1, the
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data are reported many times in comparison with Fibruline DS 5 % sample.
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As depicted in figure 2, upon addition of inulin, significant decrease in water absorption
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was recorded and our results confirmed those of Peressini and Sensidoni (2009), although we
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used white-half flours with an average quality; also dosage of short-chain fructans products
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(in powder form) was higher than in previous mentioned studies. Different authors cited by
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Peressini and Sensidoni (2009) have tried to explain the mechanisms for water absorption
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changing in the presence of inulin type products based on inulin affinity for water and its
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visco-elastic properties in solution, as well as its composition in oligomers.
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Excepting sample with 5 % Fibruline DS2 added, development time of dough increased by a gradual addition of inulin-type products in comparison with blank sample. In the same
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time the baking strength seemed to be improved although a higher additional level of inulin
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type products more than 15 % had an adverse effect. Overall the dough stability, its tenacity
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and extensibility had not respected neither significant positive nor negative correlation (with
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p<0.05) related to inulin dose increment towards 20 % Fibruline DS2. Those results were
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confirmed by rheological behaviour of dough determined by alveograph Chopin device as
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well (unshown data). That means an addition of Fibruline DS up to 15 % to the wheat flours
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may improve the strength of the dough, but results have not been concluded for a certain
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mechanism to explain its rheology. Consequently, there are other variables in addition that
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influence rheology mechanism in terms of dough matrix composition and its structure
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(linkages or interactions).
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The mixolab parameter C1 indicates the maximum torque during mixing and is used to
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determine water absorption of samples at a given consistency (C1 = 1.1 Nm +/-0.07).
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Amplitude, as curve width at C1, gives information about dough elasticity, which has
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increased with inulin product addition in dough formulation. A linear range of the function
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between variables C1 and DS2 doses was checked, but the relation was not significant at
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p<0.05, but correlation became significant when it was taken into account as the second
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dependent variable the dough temperature.
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functional properties in gluten matrix are linked together in a certain measure. For instance,
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Peressini and Sensidoni (2009) have investigated dough microstructure through confocal
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scanning laser microscopy (CSLM) and found out that shorter chain of inulins had less effect
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on changing the gluten network, but they used only 5 % inulin product. It is possible that
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higher amounts of inulin products even with DP ≤ 10 to have an disruptive effect on gluten
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matrix or its effect to be indirect as a result of the physical or physico-chemical interactions
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between inulin-inulin, inulin-gluten proteins or inulin-starch. That means the effect of fibre
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addition on dough rheology should be discussed in relation with the fibre type, its specific
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properties as well as the amount of fibre used.
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The weakening of the protein based on the mechanical work and temperature is
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described in the second zone of the mixolab curves (C1–C2). Rheological tests showed that
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addition of doses higher than 5 % of inulin type Fibruline DS2 induced significant changes of
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the dough weakening. At more than 5 % amount of inulin added to dough the torque values
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registered during mixing dropped down with a rapid temperature increasing. It is considered
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that this behaviour related to dough weakening was due to protein unfolding with effect on
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hydrophobicity modifying, as well as the increasing temperature had acted on protein
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denaturation involving the release of a large quantity of water (Haros et al. 2006; Rosell et al.
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2007 - cited by Banu et al., 2011). Moreover, we suppose that proteins’ unfolding at
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temperature less than 45-55 oC (variation domain of temperature for many proteins
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denaturation) allows a higher enzymatic attack in different sites and an easy access to disrupt
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linkages on protein chains because of changes in structural properties of proteins included
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into gluten matrix.
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Although other authors (Peressini and Sensidoni, 2009) reported lower changes in linear viscoelastic properties of dough by using improvers as inulin products with DP=10, our
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results showed that rheological behaviour was also influenced by formulation; and the
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addition of doses of inulin product (DP≤10) more than 5 % affected drastically the viscous-
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elastic behaviour of dough. It is possible that a higher addition of fibre may interrupt the
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starch-gluten matrix during processing by a „gluten-diluting effect”, too.
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As it is known, during starch gelatinization the swelling and hydration of starch granules
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induce the dough consistency increase. With rising dose of Fibruline DS2 added to flour, a
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decrease trend in gelatinization temperature along with the drop of torque to starch
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gelatinization was noticed (see figure 3). However, the ascending ratio from minimum torque
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(C2) to maximum torque (C3) proved the capability of Fibruline DS2 to delay starch
310
gelatinisation during heating.
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Figure 3. Variation of starch gelatinization (C3) based on mechanical torque and gelatinization temperature, as well as variation of Mixolab parameters values (C4 and C5) depending on percent of 5 to 20 % DS2 used. In spite of the fact that dough behaviour improved with inulin may be attributed to gelforming property, a higher dose than 10 % of Fibruline DS2 affected the stability of the hot-
319
formed gel. Also the torque (C5) corresponding to the end of the starch retrogradation period
320
dropped to 0 value in the samples improved with more than 15 % inulin product. Variation of
321
C4 and C5 parameters values depending on percent of Fibruline DS2 added (5 to 20 %) is
322
presented in figure no. 3, too.
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3.2. Bread quality
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The rheological results were confirmed by baking tests, too. Variation of loaf volume,
327
porosity and elasticity of bread crumb is introduced in figure 4. The sensorial characteristics
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of bread with inulin added were modified in terms of crust aspect and crumb properties. In
329
comparison with blank sample, the other breads had loaf volume reduced, were undeveloped,
330
with shrivelled crust and irregular pores. Also bread crumbs had become harder and darker,
331
but had a pleasant taste.
332 333
Bread crumb porosity has decreased with inulin-enrichment percent rising above 5 %, in comparison with blank sample, and this result seems to complete findings of Karolini-
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Skaradzińska et al. (2007) that have registered an improvement of the crumb porosity for an
335
amount of 4 % inulin added. The bread crumb elasticity varied, but did not in a large range. Overall the sensorial characteristics, loaf volume and physical properties of inulin-
337
enriched breads reflected a limited acceptability of those to a fortification of 5 % Fibruline
338
DS2. Is no less true that results are in accordance with findings (Skara et al., 2013; Peressini
339
and Sensidoni, 2009; Karolini-Skaradzińska et al., 2007) that bread characteristics are
340
significantly declined for addition with more than 2-3 % up to 5 % inulin.
341 342
Figure 4. Variation of loaf volume, porosity and elasticity of bread crumb
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If we refer to potential nutritional purposes, a higher dose of inulin product used in bread formulation has improved the total fibre content with better results for samples with
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more than 5 % Fibruline DS2 addition. On this point, total fibre content of bread made from
347
half-white flour with Fibruline DS2 addition were determined according with Codex
348
Alimentarius and the guidance document for competent authorities for the control of
349
compliance within EU legislation concerning the methods of analysis for determination of the
350
fibre content declared through labelling. The results showed that bread with 5 % inulin is a
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source of fibre, whilst the samples with 10 % and 15 % addition are high in fibre (according
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with definitions laid down by Regulation EC No 1924/2006).
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4. Conclusions
By using common wheat flour half-white and different amount of chicory inulin, the
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dough and loaf bread quality was assessed. Changes of the rheological behaviour were
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noticed, in terms of a general decreasing trend of dough machinability due to enzymatic
359
reactions probably influenced by changing the ratio of main compounds. Also, some
360
rheological parameters that reflect dough stability and its tenacity did not necessary follow a 13
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similar trend at a higher level of inulin more than 5 % as it was reported by other authors for
362
an amount of inulin added up to 5 %.
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The loaf volume reduction is registered whilst the total soluble fibre content of bread is
364
enhanced; this drop may be explained by dough elasticity decreasing and a lower ability of
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the dough to retain gas. Overall the bread loaves characteristics mainly affected by inulin addition were the
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volume and crust colour, and our results are in agreement with those observed by others and
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reviewed by Foschia et al (2013); Morris and Morris (2012); Ktenioudaki and Gallagher
369
(2012).
These results proved that, from technological reasons, in order to obtain bread with a
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convenient acceptable sensorial quality, it is better to be use Fibruline DS2 at a fortification
372
level of maximum 5 % inulin when bread is made from half-white flours as raw materials.
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But this dose it is not necessary efficient for a physiological and nutritional purpose aimed at
374
baking fibre-enriched products. Also, Hager et al. (2011) showed that inulin potential as fibre
375
supplement in gluten-free bread is limited. Our results indicate that 15 % Fibruline DS is a
376
maximum percent to be used in wheat bread made from half-white flour, above being
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critically for bread-making in terms of rheological behaviour of the dough and drastically
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affects the quality of end-products as well.
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5. References
381 1.
Banu, I., Stoenescu, G., Ionescu, V., Aprodu, I., 2011. Estimation of the Baking Quality
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382 383
of Wheat Flours Based on Rheological Parameters of the Mixolab Curve. Czech J Food
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Sci 29, 35–44. 2.
Bosscher, D., 2009. Fructan prebiotics derived from inulin. In: Charalampopoulos, D.,
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385 386
Rastall, R.A. (Eds), Prebiotics and probiotics science and technology, Springer, pp. 163-
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205.
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3.
Brasil, J.A., da Silveira, K.C., Magalhães Salgado, S., Souza Livera, A.V., Pinheiro de
389
Faro, Z., Barbosa Guerra, N., 2011. Effect of the addition of inulin on the nutritional,
390
physical and sensory parameters of bread, Braz J Pharm Sci 47, Jan/Mar.
391
4.
Commission Directive 2008/100/EC of 28 October 2008 amending Council Directive
392
90/496/EEC on nutrition labelling for foodstuffs as regards recommended daily
393
allowances, energy conversion factors and definitions, OJ L 285/ 29.10.2008, 9–12.
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ACCEPTED MANUSCRIPT 394
5.
Devereux, H.M., Jones, G.P., Mccormack, L., Hunter, W.C., 2003. Consumer
395
acceptability of low fat foods containing inulin and oligofructose, Journal of Food
396
Science 68, 1850–1854.
397
6.
Eastwood, M., Kritchevsky, D., 2005. Dietary fiber: how did we get where we are?, Annual Rev Nutr. 25, 1–8. doi:10.1146/annurev.nutr.25.121304.131658.
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PMID 16011456 7.
401 402
2013 8.
403 404
Euromonitor International, Global Consumer Trends: Summary of 2013 Survey Results,
Filipovic, J., Filipovic, N., Filipovic, V., 2010. The effects of commercial fibre on frozen bread dough, J Serb Chem Soc 75, 195–207.
9.
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Foschia, M., Peressini, D., Sensidoni, A., Brennan, C.S., 2013. The effects of dietary fibre addition on the quality of common cereal products, Journal of Cereal Science 58,
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216-227.
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10. Hager, A.S., Ryan, L.A.M., Schwab, C., Ganzle, M.G., O’Doherty, J.V., Arendt, E.K.,
408
2011. Influence of the soluble fibre inulin and oat glucan on quality of dough and bread,
409
Eur Food Res Technol 232, 405–413.
11. Howlett, J.F., Betteridge, V.A., Champ, M., Craig, S.A., Meheust, A., Jones, J.M., 2010.
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The definition of dietary fiber – discussions at the ninth Vahouny fiber symposium:
412
building scientific agreement, Food Nutr Res. 54, 1–5. [PMC free article]
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12. Karolini-Skaradzińska, Z., Bihuniak. P., Piotrowska, E., Wdowik, L., 2007. Properties of dough and qualitative characteristics of wheat bread with addition of inulin, Pol J
415
Food Nutr Sci 57, 267-270.
416
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13. Koryachkina, S.Y., Matveeva, T.V., Akhmedova, D.K., 2012. The inulin and oligofructose effect on quality parameters of big dark and wheat bread functional
418
properties, Int Journal of Applied and Fundamental Research 1, 28-30.
419 420 421
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14. Ktenioudaki, A., Gallagher, E., 2012. Recent advances in the development of high-fibre baked products, Trends in Food Science & Technology 28, 4-14 15. Morris, C., Morris, G., 2012. The effect of inulin and fructooligosaccharide
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supplementation on the textural, rheological and sensory properties of bread and their
423
role in weight management: A review, Food Chemistry 133, 237-248.
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16. O'Brien, C.M., Mueller, A., Scannell, A.G.M., Arendt, E.K., 2003. Evaluation of the
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effects of fats replacers on the quality of wheat bread, J Food Eng 56, 256-267.
15
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17. Park, E.Y., Jang, S.B., Lim, S.T., 2016. Effect of fructo-oligosaccharide and isomalto-
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oligosaccharide addition on baking quality of frozen dough, Food Chemistry 213, 157–
428
162.
430 431
18. Patel, S., Goyal, A., 2012. The current trends and future perspectives of prebiotics research: a review, Biotech 2, 115–125. 19. Peressini, D., Sensidoni, A., 2009. Effect of soluble dietary fibre on rheological and
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breadmaking properties of wheat doughs, Journal of Cereal Science 49, 190-201.
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20. Regulation (EC) No 1924/2006 of the European Parliament and of the Council of 20
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December 2006 on nutrition and health claims made on foods. Official Journal of the
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European Union L404, 9-25.
436
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21. Regulation 1169/2011/EU of the European Parliament and of the Council 25 October 2011 of on the provision of food information to consumers, amending Regulations (EC)
438
No 1924/2006 and (EC) No 1925/2006 of the European Parliament and of the Council,
439
and repealing Commission Directive 87/250/EEC, Council Directive 90/496/EEC,
440
Commission Directive 1999/10/EC, Directive 2000/13/EC of the European Parliament
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and of the Council, Commission Directives 2002/67/EC and 2008/5/EC and
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Commission Regulation (EC) No 608/2004, OJ L 304/ 22.11.2011, 18–63.
444 445
22. Roberfroid, M.B., 2007. Inulin-type fructans: functional food ingredients, J Nutr. 137
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(11 Suppl), 2493S–2502S. PMID 17951492. 23. Skara, N., Novotni, D., Cukelj, N., Smerdel, B., Curic, D., 2013. Combined effects of inulin, pectin and guar gum on the quality and stability of partially baked frozen bread,
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Food Hydrocolloids 30, 428-436.
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24. Volpini-Rapina, L.F., Sokei, F.R., Conti-Silva, A.C., 2012. Sensory profile and preference mapping of orange cakes with addition of prebiotics inulin and oligofructose,
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LWT - Food Science and Technology 48, 37-42.
451 452
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25. Wang, J., Rosell, C.M., de Barber, C.B., 2002. Effect of the addition of different fibre on dough performance and bread quality, Food Chem 79, 221-226.
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26. Zahn, S., Pepke, F., Rohm, H., 2010. Effect of inulin as a fat replacer on texture and
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sensory properties of muffins, International Journal of Food Sci and Tech 45, 2531-
455
2537.
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27. USDA, 2005. Chapter 7: Dietary, Functional and Total Fiber. In: Dietary Reference
457
Intakes for Energy, Carbohydrate, fiber, Fat, Fatty Acids, Cholesterol, Protein, and
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Amino Acids (Macronutrients), National Agricultural Library and National Academy of
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Sciences, Institute of Medicine, Food and Nutrition Board, pp. 339-421. 16
ACCEPTED MANUSCRIPT Table 3. Mixolab parameters for dough with 5 % up to 20 % Fibruline DS2 added Characteristics Samples
C1
Torque (Nm) C2 C3 C4
C5
α slope
β slope
γ Amplitude slope (Nm)
1.07
0.45
1.29
1.93
3.11
-0.046
0.144
0.070
0.08
10% DS2
1.18
0.40
0.58
1.57
2.70
-0.092
0.052
0.204
0.09
15% DS2
1.33
0.35
0.68
0.66
0
-0.004
0.052
-0.020
0.11
20% DS2
1.29
0.30
0.30
0.44
0.71
-0.192
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5% DS2
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-0.006
0.018
0.13
ACCEPTED MANUSCRIPT Highlights: Rheological behaviour of inulin-enriched flours assessed with mixolab Chopin.
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Inulin potential as fibre enrichment in wheat bread is limited.
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A fortification level of 5% inulin to half-white flour has better results.
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A significant amount of added inulin fibre has a detrimental effect in bread-making
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A fortification level of maximum 15% inulin proposed for a “high-fibre” bread.
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S0733-5210(16)30217-X
DOI:
10.1016/j.jcs.2017.03.029
Reference:
YJCRS 2330
To appear in:
Journal of Cereal Science
Received Date: 8 December 2016 Revised Date:
11 March 2017
Accepted Date: 27 March 2017
Please cite this article as: Sirbu, A., Arghire, C., Functional bread: Effect of inulin-type products addition on dough rheology and bread quality, Journal of Cereal Science (2017), doi: 10.1016/j.jcs.2017.03.029. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Title: Functional Bread: Effect of Inulin-Type Products Addition on Dough Rheology and Bread Quality Authors: Alexandrina SIRBU1,2, Camelia ARGHIRE2
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Affiliations: Constantin Brancoveanu University, FMMAE Ramnicu Valcea, 39 Nicolae Balcescu Bld., Romania; cell
+40744993123; e-mail [email protected], [email protected] (Corresponding author) COPE Ltd., Conacul Cantacuzino-Pascanu, Costisa- Neamtz, Romania; e-mail [email protected]
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Key words: functional fibre and inulin; mixolab; rheological behaviour; half-white bread.
ACCEPTED MANUSCRIPT Abstract The concerns for a healthy diet in terms of the consumption of baked products as fibreenriched ones have been highlighted by increased consumers demand, food legislation and targeting manufacturers offer to healthy food. The objective of this study was to assess the effect of some inulin-type products added in bread-making aimed at producing functional
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bakery goods. In this purpose some physico-chemical characteristics and technological properties of the Romanian wheat flour half-white with addition of 5 %, 10 %, 15 % and 20 % inulin commercial products (% basis flour) were evaluated. Rheological behaviour was investigated using mixolab Chopin and baking tests for fibre-enriched products were
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performed. Changes of the rheological behaviour were noticed, in terms of a general
decreasing trend of dough machinability due to enzymatic reactions probably influenced by changing the ratio of the main compounds and their interactions. Overall the bread loaves
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characteristics mainly affected by inulin addition were the volume and crust colour. Results indicated that inulin potential as fibre enrichment in wheat bread is limited, 15 % Fibruline DS being a maximum percent to be used in bread-making of half-white flour, a dosage above being critically for dough rheological behaviour and the quality of high-fibre
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bread.
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1. Introduction
2 3
1.1. Functional fibre for healthier baked products
4 5
Nowadays consumers are more aware about healthy eating aimed at improving their quality of life and in this regard their main demands refer to food nutrients and their
7
functionality (e.g. Euromonitor International (2013) through the Global Consumer Trends
8
Survey showed that consumers look for “added vitamins or fibre” on foodstuffs labels).
9
Naturally, the concerns for a healthy diet in terms of food consumption have been also
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highlighted by food legislation (e.g. Reg. EC No 1924/2006, including all amendments, has
11
imposed specific provisions concerning the use of nutrition and health claims about foods
12
through goods labelling). For gaining a competitive advantage on the market, bakery
13
manufacturers tailored adequately their food commodities and producers have lined up the
14
offer based on evolving consumers’ preferences. Consequently, trends within the bakery and
15
pastry market focused on health and wellness products have followed double strategies based
16
on either health or nutrition claims. A health claim refers to the statement about a relationship
17
between food and health, whilst the nutrition claim concerns nutrients or ingredients that have
18
a nutritional function or a physiological effect proved scientifically. In that way baking
19
industry has started to develop a wide range of baked products, such as: vitamin-enriched,
20
fortified with minerals, „high” protein, “low” sugar, “rich” fibre, “light” fat, „gluten-free” etc.
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On this point, many researches have paid attention to baked products with fibre addition, too.
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In order to study dietary fibre (DF), since the 1970s two requirements have had to be
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met, namely fibre definition and appropriate methods of analysis. It seems that the most
24
debates referred to definition issues. For instance, in the period 2005-2013, USDA, Institute
25
of Medicine (IOM), American Association of Cereal Chemists International (AACCI),
26
European Commission and European Food Safety Authority (EFSA), other national
27
Commissions as well as Codex Alimentarius Commission have had different approach on this
28
topic. Although their agreed definitions bear many similarities, some important differences
29
exist with regards to types/ chemical and functional issues. According with USDA (2005), the
30
dietary fibre is defined as non-digestible carbohydrates and lignin that are intrinsic and intact
31
in plants, whilst a functional fibre is defined as isolated, non-digestible carbohydrates that
32
have been shown to have beneficial physiological effects in humans. Official definitions of
33
dietary fibre that were expressed by European and Codex Alimentarius Commissions are
34
quite different. Commission Directive 2008/100/EC amending Council Directive
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36
information to consumers lay down definition of „fibre” as „carbohydrate polymers with three
37
or more monomeric units, which are neither digested nor absorbed in the human small
38
intestine and belong to the following categories: -edible carbohydrate polymers naturally
39
occurring in the food as consumed; -edible carbohydrate polymers which have been obtained
40
from food raw material by physical, enzymatic or chemical means and which have a
41
beneficial physiological effect demonstrated by generally accepted scientific evidence; -edible
42
synthetic carbohydrate polymers which have a beneficial physiological effect demonstrated
43
by generally accepted scientific evidence." Although Codex Alimentarius Commission tried
44
to align dietary fibre definitions there are still a few items which differ from those introduced
45
above (Howlett et al, 2010).
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Other debates have arisen concerning the fact that fibre should be traditionally consumed as plant material; some scientists have promoted the spiked fibre in the food matrix
48
with emphasis mainly on edible aspects and physiological benefits of these carbohydrate
49
polymers. At the moment it is acknowledged the role of both intrinsic and added fibre.
50
However, regarding fibre’s definition, a mutual consensus appeared about the importance to
51
prove the beneficial physiological effects of these kind of non-digestible carbohydrate
52
polymers used. In fact majority provisions on definition of dietary fibre claims as mandatory
53
the benefit to health to be demonstrated by generally accepted scientific evidence to
54
competent authorities.
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Generally speaking, dietary fibre are classified based on their solubility in water. Thus, soluble DF are oligosaccharides, pectins, β–glucans, and galacto-manan gums alginate,
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psyllium fibre; and insoluble fibre are cellulose, hemicellulose, and lignin. According IOM
58
(2001-cited in USDA, 2005) dietary fibre consist of plant non-starch polysaccharides (e.g.
59
cellulose, pectin, gums, hemicellulose, β-glucans, as part of oat and wheat bran), plant
60
carbohydrates that are not recovered by alcohol precipitation (e.g., inulin, oligosaccharides,
61
and fructans), lignin, and some resistant starch. Potential functional fibre for food labelling
62
include isolated, non-digestible plant (e.g., resistant starch, pectin, and gums), animal (e.g.,
63
chitin and chitosan), or commercially produced (e.g. resistant starch, polydextrose, inulin, and
64
indigestible dextrins) carbohydrates. As is depicted above, there is also other criteria used for
65
dietary fibre classification, as chemical or botanical ones.
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It was shown that dietary or/and functional fibre have one or more beneficial
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physiological effects such as: decrease intestinal transit time; increase stool bulk; is digested
68
through fermentation by colonic microflora; reduce blood total or/ and LDL cholesterol 2
ACCEPTED MANUSCRIPT levels; reduce post-prandial blood glucose, or reduce blood insulin levels. As Eastwood and
70
Kritchevsky (2005) reviewed, the fibre acts in the digestive tract by changing either the nature
71
of the contents of the gastrointestinal tract or how other chemicals and nutrients are absorbed.
72
Beside the physiological effect of the fibre, their functionality has been studied in the etiology
73
of diseases (cardiovascular and heart disease, colonic diverticulosis, obesity, cancer etc.) and
74
epidemiology because of the evidence associating dietary fibre with reduced health risks.
75
Although fibre are used in different diets for more than a century, a scientific holistic
76
understanding in-depth in nutrition and medical trials is still in progress.
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A third pathway for research of the dietary fibre addresses straightly to food domain, and consists of the assessment of their functionality in food matrix through physical-chemical
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characteristics (e.g. water binding, rheological behaviour etc.) with relevant impact for
80
technological performances and sensorial characteristics of the end-products that can be
81
acceptable in terms of consumers preferences.
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Fibres vary in structure and functions and it seems that an optimal diet in fibre refers at
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the same time to the right amount of fibre and a suitable balance between them. For instance,
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a daily recommended intake as an adequate intake (AI) ranges from 21 to 38 g of fibre,
85
depending on age and gender characteristics as well as referees (WHO/FAO, EFSA, UK Food
86
Standards Agency etc.). Scientific literature shows that dietary fibre are required to be
87
ingested for an obvious physiological effect at a minimum intake of 12 g/day, but some voice
88
the opinion that an increase DF intake is necessary to be promoted for both prevention and
89
management of disease. Nevertheless dietary fibre cannot be an essential part of the diet, but
90
nowadays a healthy diet should include various fibre types. Also, the doses of fibre
91
enrichment should be related with the types of bakery products (bread, biscuits, pastry,…) as
92
well as with the food purposes (conventional food, functional ones and foods for specific
93
groups – PARNUTS). According with food legislation (Regulation EC No 1924/2006) drawn
94
up, nutritional claims regarding fibre content can be “high-fibre” for 6 g DF per 100 g or 3 g
95
per 100 kcal or 20 % of daily reference value per serving, while a food as a source of fibre
96
means the product contains at least 3 g of fibre per 100 g or at least 1,5 g of fibre per 100 kcal.
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1.2. Inulin fibre
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As it mentioned above, inulin type-fructans fulfil all five basic attributes of dietary fibre.
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Inulin, oligofructose and fructooligosaccharides (FOS) naturally occur in a large variety of
102
edible plants as storage carbohydrates; but they are mainly industrial processed from chicory 3
ACCEPTED MANUSCRIPT and Jerusalem artichoke. They have a polydisperse carbohydrate composition consisting
104
mainly, if not exclusively, of β-(2←1) fructosyl-fructose linked oligomeric carbohydrates
105
with linear chains and polymers with a different polymerisation degree (DP) ranging from 3
106
to 60 and, in general, with a terminal glucose unit (Roberfroid, 2007). Because of their β–
107
(2←1) glycosidic linkages, inulin type-fructans have resistance to enzymatic digestion in the
108
upper gastrointestinal tract; but are quantitatively fermented by the large bowel endogenous
109
microbiota, being associated with a surely prebiotic effect and other health benefits, such as:
110
laxation, normalization of blood lipid concentrations, attenuation of blood glucose responses
111
(USDA, 2005), modulation of the composition of the intestinal microbiota and improvement
112
of gut functions (Bosscher et al, 2009; Patel and Goyal, 2012), potential enhancement of
113
calcium and magnesium absorption (Roberfroid, 2007).
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Inulin products may contribute to a well-balanced diet by increasing the fibre content and diversifying the fibre sources, with multiple functional beneficial effects on human health
116
and nutrition. The recommended dose of inulin for its different physiological benefits varies
117
between 10 g and 15 g. Nevertheless, it seems that the over-dosage lead to a malabsorption
118
and digestive distress for some people. Also, the data on a potential allergenicity of inulin and
119
oligofructose is quite limited. Regarding nutrition, beside its prebiotic role, inulin contains
120
25–30% the food energy of sugar or other carbohydrates and 10–15% the food energy of fat,
121
reason for which it has started to replace sugar, fat, and flour in different recipes of foodstuffs
122
and nutritional supplements. Extensive research was done in order to characterise inulin
123
behaviour in food matrix or assess its technological properties with a final purpose to be used
124
as ingredient for obtaining functional food. The bakery products have been good vectors for
125
prebiotic or high-fibre foodstuffs and have attracted interest for inulin, oligofructose and FOS
126
enrichment aimed at obtaining either low-fat baked goods or carbohydrate substitution in
127
dough matrix (Volpini-Rapina et al., 2012; Brasil et al., 2011; Zahn et al., 2010; Devereux et
128
al., 2003; etc.). Different research teams have investigated whether inulin-enriched breads are
129
feasible for bread-making in terms of dough behaviour, bread characteristics and consumers
130
acceptance and many studies proved that inulin allows the developing of baked products with
131
an acceptable or comparable sensorial quality of end-products related to regular ones
132
(Filipovic et al., 2010; O’Brien et al., 2003; Wang et al., 2002). Although many investigations
133
have been performed, new research needs become apparent in order to understand overall
134
conditions and mechanisms that influence dough rheology and baking science.
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1.3. Rationale and research questions
138 The objective of this study refers to assessment of some inulin-type fructans products
140
used in bread-making aimed at producing bakery goods for a better diet. By using different
141
doses of inulin-type products up to a percent, which justifies a prebiotic claim, their effect on
142
the properties of common wheat dough and bread was evaluated. Also in many previous
143
studies they used inulin-type fructans with a degree of polimerization (DP) greater than 10
144
because of their differences in solubility in comparison with those with DP < 10, but as we
145
have already introduced above the arbitrary cut-off at DP=10 does not have a ground reason
146
either analytically or physiologically (Howlett et al, 2010). In this respect we focus our
147
research on addition of inulin-type fructans products with DP < 10 in dough and bread recipes.
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139
Investigations of other researchers focus on white and dark breads (e.g. Koryachkina et
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al., 2012; Brasil et al., 2011), reason for what the half-white flours have been chosen for our
150
experimental. Another rationale of usage half-white wheat flour (type 800) is that inulin and
151
oligofructose may affect the quality of big dark wheat breads (as shown Koryachkina et al.,
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2012). Although flours are made from common wheat, another interest of this study has been
153
directed towards the assessment of Romanian grains harvested for commercial purpose. In this study the dough behaviour has been assessed mainly through mixolab method,
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whilst in the majority of previous studies the dough performances with addition of inulin type
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fibre were investigated by using other methodologies and equipment, such as farinograph,
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extensograph, alveograph and mixograph (as reviewed Foschia et al, 2013; Ktenioudaki and
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Gallagher, 2012; Morris and Morris, 2012).
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2. Experimental
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2.1. Materials and methods
As raw material, half-white commercial flour from Romanian common wheat (Triticum
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aestivum) was used. Samples were made on duplicate. Protein content, moisture content,
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falling number, ash content, wet gluten content, acidity, alveograph and mixolab data have
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been accomplished according to Romanian and international standard methods for flours and
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dough, as is shown in table 1. Overall results indicated an average to good quality of flour
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chosen like start material (see table 1).
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Table 1. Quality assessment of the flour used in experiments
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Assessment of flour quality, as raw material (F3) Characteristics Values Analysis method Moisture content, % 14.0 ISO 712:2009 Ash content, % 0.80 SR 90:2007 Protein content, % 11.8 SR 13013-3:1994 SR EN ISO 21415-1:2007 Wet gluten, % 28.8 Acidity, grd. 2.8 SR 90:2007 Falling number, s 305 ISO 3093:2010 Rheological behaviour of dough Alveograph method Mixolab method (according to SR EN ISO 27971:2008) ((according to ISO 17718:2013) Alveograph parameters Values Tenacity P, mm 67 Water absorption, % (base 14%) Extensibility L, mm 103 Maximum torque during mixing C1,Nm P/L ratio 0.65 Amplitude, Nm Energy/baking strength W 10-4J 185 Stability, min Index of swelling G, mm 22.6 Protein weakening based on mechanical work and temperature C2, Nm Elasticity index Ie, % 45.6 Starch gelatinisation C3, Nm Stability of starch gel formed C4, Nm Starch retrogradation during cooling stage C5, Nm α slope, Nm/min β slope, Nm/min γ slope, Nm/min
Values 58.1 1.12 0.07 7.38 0.45 1.73 1.66
2.50 -0.068 0.446 -0.026
In experimental we used as soluble fibre three kinds of chicory fructans produced by Cosucra (Belgium) and supplied by Enzymes & Derivates Romania, namely: Inulin Instant
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(inulin), Fibruline DS2 (inulin) and Fibrulose F97 (oligofructose). These are white powders
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with a neutral to light-sweet taste. Their characteristics are introduced in table 2.
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Table 2. Quality characteristics of chicory fructans used as soluble fibre in experiments Nutritional and biochemical characteristics Energy, kcal/kJ/100 g Dry matter (g/100 g) - in which reducing sugars Dietary fibre (g/100 g) - in which chicory fructans Carbohydrates-free/100 g Relative sweetening power, % Sweetening power DE, %
Inulin Instant
Fibrulose F97
Fibruline DS2
208/840 96 8.0 88.0 88.0 8.0 10 5-10
198/795 96 3.0 93.0 93.0 3.0 10 10-15
196/786 96 2.0 94.0 94.0 2.0 2 2-7
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10
10
2
DP: ≈10
DP≤10: 70±5% DP≤20: 94±5% DP>20: 5±5%
DP: <10
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2.2. Rheological performance
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information about the relationship between the force and deformation, and there was studied
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by using Alveograph and Mixolab devices. Through the Alveograph method the dough is
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submitted to biaxial deformation, while the dough prepared within Mixolab equipment is
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subjected to a dual mixing and temperature constraint. The Chopin Mixolab device allows
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characterisation of thermal and mechanical behaviour of flours, namely water absorption
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capacity and kneading stability, gelatinisation temperature, amylase activity and starch
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retrogradation.
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Rheological behaviour of dough by mixolab Chopin was assessed by using standard Mixolab software, with the specific protocol (ICC no. 173) (Rotational speed: 80 rpm; Target
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value 1.1 +/- 0.07 Nm; tank temperature 30˚C, heating rate 2 ˚C/min). As reference
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methodology, it was applied ISO 17718:2013 for determination of rheological behaviour as a
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function of mixing and temperature increase.
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2.3. Baking procedure
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Baking tests were performed based on recipe, which comprised the following
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ingredients: flour and chicory fructans products (see 2.1.), baking yeast - Saccharomyces
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cerevisiae (Pakmaya; supplier ROMPAK SRL Paşcani Romania), salt (commercial iodized
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salt), and water. Each raw material (of yeast, salt and water) had an appropriate quality for
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bread-making determined according with the standard methods of analysis (SR 13360 – 1995,
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STAS 985- 1979,..).
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Breads were made in triplicate and baking recipe consists of 1000 g flour, 30 g fresh
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baking yeast, 15 g salt, a quantity of water according with water absorbtion (i.e. 581 ml), and
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different doses of inulin-type products. In dough formulation the addition of chicory fructans
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was made as percentage, namely 5 %, 10 %, 15 % and 20 % (basis 100 g flour). Breads were
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obtained through a direct method.
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Regarding the bread-making, dough was prepared by mixing (7…10 min) until a developed and smooth dough was obtained (at 30 oC); then the bulk fermentation for 150 min
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at 30 oC was done prior to division in three parts, hand moulding and final proof for 50 min at
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a temperature of 30 oC with a relative humidity of 85 %. Dough pieces were baked for 30 min
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at 230 oC and after withdrawal from the oven were put into a place for cooling (1-2 h). Bread
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quality was evaluated afterwards.
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The loaf volume and physical properties (elasticity, porosity) of the breads were
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evaluated by means of the Romanian method for baking test performing (SR 91-2007). Loaf
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volume was measured by rapeseed displacement. Elasticity was assessed as crumb hardness at
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uniaxial compression test and porosity was determined as a total volume of hollows of a
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known volume of breadcrumb.
Statistical assay was computed by the software SPSS (v. 11.0) for Windows.
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3. Results and Discussion
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Preliminary research (unshown data) proved that the better choice for our experiments is Fibruline DS2. This product consists of the highest soluble fibre (%) and the lowest reducing
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sugars. Also it comes with lower energy intake in comparison with the other chicory fructans.
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However, its solubility is related with the chain length (DP<10). Further, the technological
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results with addition of 5 %, 10 %, 15 % and 20 % inulin - Fibruline DS2 (% basis flour) are
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introduced.
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3.1. Rheological evaluation
Rheological behaviour measured by using mixolab Chopin is expressed in figures 1 and
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2. Mixolab data for dough samples with 5 %, respectively 15 % Fibruline DS2 (DS2) added
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are introduced in figure no. 1, while in figure 2 the radial diagram made on Mixolab for a
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comparative assessment of rheological behaviour of dough in relation with all doses of inulin-
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type product used in experimental is done.
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a) 5 % DS2
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b) 15 % DS2
Figure 1. Mixolab data for dough with 5 % and 15 % Fibruline DS2 added
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Figure 2. Mixolab diagram for samples with Fibruline DS2 (5 %; 10 %; 15 %; 20 %)
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dough rheology and baking process at doses varied from 1 % to 10 % mainly, and more
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convenient or acceptable results were obtained for an inulin dose of 5-6 % (Park et al, 2016;
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Brasil et al., 2011; Peressini and Sensidoni, 2009; etc). But in our experiments the soluble
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fibre content was doubled and increased up to 20 % to be surely for its functional effect
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(complying with regulations requirements). For that reason, as is also shown in figure 1, the
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data are reported many times in comparison with Fibruline DS 5 % sample.
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As depicted in figure 2, upon addition of inulin, significant decrease in water absorption
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was recorded and our results confirmed those of Peressini and Sensidoni (2009), although we
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used white-half flours with an average quality; also dosage of short-chain fructans products
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(in powder form) was higher than in previous mentioned studies. Different authors cited by
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Peressini and Sensidoni (2009) have tried to explain the mechanisms for water absorption
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changing in the presence of inulin type products based on inulin affinity for water and its
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visco-elastic properties in solution, as well as its composition in oligomers.
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Excepting sample with 5 % Fibruline DS2 added, development time of dough increased by a gradual addition of inulin-type products in comparison with blank sample. In the same
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time the baking strength seemed to be improved although a higher additional level of inulin
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type products more than 15 % had an adverse effect. Overall the dough stability, its tenacity
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and extensibility had not respected neither significant positive nor negative correlation (with
262
p<0.05) related to inulin dose increment towards 20 % Fibruline DS2. Those results were
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confirmed by rheological behaviour of dough determined by alveograph Chopin device as
264
well (unshown data). That means an addition of Fibruline DS up to 15 % to the wheat flours
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may improve the strength of the dough, but results have not been concluded for a certain
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mechanism to explain its rheology. Consequently, there are other variables in addition that
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influence rheology mechanism in terms of dough matrix composition and its structure
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(linkages or interactions).
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The mixolab parameter C1 indicates the maximum torque during mixing and is used to
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determine water absorption of samples at a given consistency (C1 = 1.1 Nm +/-0.07).
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Amplitude, as curve width at C1, gives information about dough elasticity, which has
272
increased with inulin product addition in dough formulation. A linear range of the function
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between variables C1 and DS2 doses was checked, but the relation was not significant at
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p<0.05, but correlation became significant when it was taken into account as the second
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dependent variable the dough temperature.
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functional properties in gluten matrix are linked together in a certain measure. For instance,
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Peressini and Sensidoni (2009) have investigated dough microstructure through confocal
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scanning laser microscopy (CSLM) and found out that shorter chain of inulins had less effect
280
on changing the gluten network, but they used only 5 % inulin product. It is possible that
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higher amounts of inulin products even with DP ≤ 10 to have an disruptive effect on gluten
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matrix or its effect to be indirect as a result of the physical or physico-chemical interactions
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between inulin-inulin, inulin-gluten proteins or inulin-starch. That means the effect of fibre
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addition on dough rheology should be discussed in relation with the fibre type, its specific
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properties as well as the amount of fibre used.
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The weakening of the protein based on the mechanical work and temperature is
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described in the second zone of the mixolab curves (C1–C2). Rheological tests showed that
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addition of doses higher than 5 % of inulin type Fibruline DS2 induced significant changes of
289
the dough weakening. At more than 5 % amount of inulin added to dough the torque values
290
registered during mixing dropped down with a rapid temperature increasing. It is considered
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that this behaviour related to dough weakening was due to protein unfolding with effect on
292
hydrophobicity modifying, as well as the increasing temperature had acted on protein
293
denaturation involving the release of a large quantity of water (Haros et al. 2006; Rosell et al.
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2007 - cited by Banu et al., 2011). Moreover, we suppose that proteins’ unfolding at
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temperature less than 45-55 oC (variation domain of temperature for many proteins
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denaturation) allows a higher enzymatic attack in different sites and an easy access to disrupt
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linkages on protein chains because of changes in structural properties of proteins included
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into gluten matrix.
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Although other authors (Peressini and Sensidoni, 2009) reported lower changes in linear viscoelastic properties of dough by using improvers as inulin products with DP=10, our
301
results showed that rheological behaviour was also influenced by formulation; and the
302
addition of doses of inulin product (DP≤10) more than 5 % affected drastically the viscous-
303
elastic behaviour of dough. It is possible that a higher addition of fibre may interrupt the
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starch-gluten matrix during processing by a „gluten-diluting effect”, too.
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As it is known, during starch gelatinization the swelling and hydration of starch granules
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induce the dough consistency increase. With rising dose of Fibruline DS2 added to flour, a
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decrease trend in gelatinization temperature along with the drop of torque to starch
308
gelatinization was noticed (see figure 3). However, the ascending ratio from minimum torque
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(C2) to maximum torque (C3) proved the capability of Fibruline DS2 to delay starch
310
gelatinisation during heating.
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Figure 3. Variation of starch gelatinization (C3) based on mechanical torque and gelatinization temperature, as well as variation of Mixolab parameters values (C4 and C5) depending on percent of 5 to 20 % DS2 used. In spite of the fact that dough behaviour improved with inulin may be attributed to gelforming property, a higher dose than 10 % of Fibruline DS2 affected the stability of the hot-
319
formed gel. Also the torque (C5) corresponding to the end of the starch retrogradation period
320
dropped to 0 value in the samples improved with more than 15 % inulin product. Variation of
321
C4 and C5 parameters values depending on percent of Fibruline DS2 added (5 to 20 %) is
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presented in figure no. 3, too.
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3.2. Bread quality
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The rheological results were confirmed by baking tests, too. Variation of loaf volume,
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porosity and elasticity of bread crumb is introduced in figure 4. The sensorial characteristics
328
of bread with inulin added were modified in terms of crust aspect and crumb properties. In
329
comparison with blank sample, the other breads had loaf volume reduced, were undeveloped,
330
with shrivelled crust and irregular pores. Also bread crumbs had become harder and darker,
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but had a pleasant taste.
332 333
Bread crumb porosity has decreased with inulin-enrichment percent rising above 5 %, in comparison with blank sample, and this result seems to complete findings of Karolini-
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Skaradzińska et al. (2007) that have registered an improvement of the crumb porosity for an
335
amount of 4 % inulin added. The bread crumb elasticity varied, but did not in a large range. Overall the sensorial characteristics, loaf volume and physical properties of inulin-
337
enriched breads reflected a limited acceptability of those to a fortification of 5 % Fibruline
338
DS2. Is no less true that results are in accordance with findings (Skara et al., 2013; Peressini
339
and Sensidoni, 2009; Karolini-Skaradzińska et al., 2007) that bread characteristics are
340
significantly declined for addition with more than 2-3 % up to 5 % inulin.
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Figure 4. Variation of loaf volume, porosity and elasticity of bread crumb
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If we refer to potential nutritional purposes, a higher dose of inulin product used in bread formulation has improved the total fibre content with better results for samples with
346
more than 5 % Fibruline DS2 addition. On this point, total fibre content of bread made from
347
half-white flour with Fibruline DS2 addition were determined according with Codex
348
Alimentarius and the guidance document for competent authorities for the control of
349
compliance within EU legislation concerning the methods of analysis for determination of the
350
fibre content declared through labelling. The results showed that bread with 5 % inulin is a
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source of fibre, whilst the samples with 10 % and 15 % addition are high in fibre (according
352
with definitions laid down by Regulation EC No 1924/2006).
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4. Conclusions
By using common wheat flour half-white and different amount of chicory inulin, the
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dough and loaf bread quality was assessed. Changes of the rheological behaviour were
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noticed, in terms of a general decreasing trend of dough machinability due to enzymatic
359
reactions probably influenced by changing the ratio of main compounds. Also, some
360
rheological parameters that reflect dough stability and its tenacity did not necessary follow a 13
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similar trend at a higher level of inulin more than 5 % as it was reported by other authors for
362
an amount of inulin added up to 5 %.
363
The loaf volume reduction is registered whilst the total soluble fibre content of bread is
364
enhanced; this drop may be explained by dough elasticity decreasing and a lower ability of
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the dough to retain gas. Overall the bread loaves characteristics mainly affected by inulin addition were the
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volume and crust colour, and our results are in agreement with those observed by others and
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reviewed by Foschia et al (2013); Morris and Morris (2012); Ktenioudaki and Gallagher
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(2012).
These results proved that, from technological reasons, in order to obtain bread with a
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convenient acceptable sensorial quality, it is better to be use Fibruline DS2 at a fortification
372
level of maximum 5 % inulin when bread is made from half-white flours as raw materials.
373
But this dose it is not necessary efficient for a physiological and nutritional purpose aimed at
374
baking fibre-enriched products. Also, Hager et al. (2011) showed that inulin potential as fibre
375
supplement in gluten-free bread is limited. Our results indicate that 15 % Fibruline DS is a
376
maximum percent to be used in wheat bread made from half-white flour, above being
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critically for bread-making in terms of rheological behaviour of the dough and drastically
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affects the quality of end-products as well.
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5. References
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Banu, I., Stoenescu, G., Ionescu, V., Aprodu, I., 2011. Estimation of the Baking Quality
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of Wheat Flours Based on Rheological Parameters of the Mixolab Curve. Czech J Food
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Bosscher, D., 2009. Fructan prebiotics derived from inulin. In: Charalampopoulos, D.,
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Rastall, R.A. (Eds), Prebiotics and probiotics science and technology, Springer, pp. 163-
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Brasil, J.A., da Silveira, K.C., Magalhães Salgado, S., Souza Livera, A.V., Pinheiro de
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Faro, Z., Barbosa Guerra, N., 2011. Effect of the addition of inulin on the nutritional,
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physical and sensory parameters of bread, Braz J Pharm Sci 47, Jan/Mar.
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Commission Directive 2008/100/EC of 28 October 2008 amending Council Directive
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90/496/EEC on nutrition labelling for foodstuffs as regards recommended daily
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allowances, energy conversion factors and definitions, OJ L 285/ 29.10.2008, 9–12.
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Devereux, H.M., Jones, G.P., Mccormack, L., Hunter, W.C., 2003. Consumer
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acceptability of low fat foods containing inulin and oligofructose, Journal of Food
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Science 68, 1850–1854.
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Eastwood, M., Kritchevsky, D., 2005. Dietary fiber: how did we get where we are?, Annual Rev Nutr. 25, 1–8. doi:10.1146/annurev.nutr.25.121304.131658.
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Foschia, M., Peressini, D., Sensidoni, A., Brennan, C.S., 2013. The effects of dietary fibre addition on the quality of common cereal products, Journal of Cereal Science 58,
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10. Hager, A.S., Ryan, L.A.M., Schwab, C., Ganzle, M.G., O’Doherty, J.V., Arendt, E.K.,
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2011. Influence of the soluble fibre inulin and oat glucan on quality of dough and bread,
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Eur Food Res Technol 232, 405–413.
11. Howlett, J.F., Betteridge, V.A., Champ, M., Craig, S.A., Meheust, A., Jones, J.M., 2010.
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building scientific agreement, Food Nutr Res. 54, 1–5. [PMC free article]
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supplementation on the textural, rheological and sensory properties of bread and their
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role in weight management: A review, Food Chemistry 133, 237-248.
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16. O'Brien, C.M., Mueller, A., Scannell, A.G.M., Arendt, E.K., 2003. Evaluation of the
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effects of fats replacers on the quality of wheat bread, J Food Eng 56, 256-267.
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17. Park, E.Y., Jang, S.B., Lim, S.T., 2016. Effect of fructo-oligosaccharide and isomalto-
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oligosaccharide addition on baking quality of frozen dough, Food Chemistry 213, 157–
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18. Patel, S., Goyal, A., 2012. The current trends and future perspectives of prebiotics research: a review, Biotech 2, 115–125. 19. Peressini, D., Sensidoni, A., 2009. Effect of soluble dietary fibre on rheological and
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breadmaking properties of wheat doughs, Journal of Cereal Science 49, 190-201.
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20. Regulation (EC) No 1924/2006 of the European Parliament and of the Council of 20
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and repealing Commission Directive 87/250/EEC, Council Directive 90/496/EEC,
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Commission Directive 1999/10/EC, Directive 2000/13/EC of the European Parliament
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and of the Council, Commission Directives 2002/67/EC and 2008/5/EC and
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25. Wang, J., Rosell, C.M., de Barber, C.B., 2002. Effect of the addition of different fibre on dough performance and bread quality, Food Chem 79, 221-226.
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26. Zahn, S., Pepke, F., Rohm, H., 2010. Effect of inulin as a fat replacer on texture and
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27. USDA, 2005. Chapter 7: Dietary, Functional and Total Fiber. In: Dietary Reference
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Amino Acids (Macronutrients), National Agricultural Library and National Academy of
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Sciences, Institute of Medicine, Food and Nutrition Board, pp. 339-421. 16
ACCEPTED MANUSCRIPT Table 3. Mixolab parameters for dough with 5 % up to 20 % Fibruline DS2 added Characteristics Samples
C1
Torque (Nm) C2 C3 C4
C5
α slope
β slope
γ Amplitude slope (Nm)
1.07
0.45
1.29
1.93
3.11
-0.046
0.144
0.070
0.08
10% DS2
1.18
0.40
0.58
1.57
2.70
-0.092
0.052
0.204
0.09
15% DS2
1.33
0.35
0.68
0.66
0
-0.004
0.052
-0.020
0.11
20% DS2
1.29
0.30
0.30
0.44
0.71
-0.192
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5% DS2
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0.018
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ACCEPTED MANUSCRIPT Highlights: Rheological behaviour of inulin-enriched flours assessed with mixolab Chopin.
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Inulin potential as fibre enrichment in wheat bread is limited.
•
A fortification level of 5% inulin to half-white flour has better results.
•
A significant amount of added inulin fibre has a detrimental effect in bread-making
•
A fortification level of maximum 15% inulin proposed for a “high-fibre” bread.
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