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Dehydrated apple matrix supplemented with agave fructans, inulin, and oligofructose
LWT - Food Science and Technology 65 (2016) 1059e1065
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Dehydrated apple matrix supplemented with agave fructans, inulin, and oligofructose lez-Herrera a, Olga Miriam Rutiaga-Quin ~ ones c, Silvia Marina Gonza bal Noe Aguilar a, Luz Araceli Ochoa-Martínez c, Juan Carlos Contreras-Esquivel a, Cristo pez b, Raúl Rodríguez-Herrera a, * Mercedes G. Lo rdenas V. s/n. Col. República Ote, noma de Coahuila, Blvd. V. Carranza e Ing. Jos Food Research Department, School of Chemistry, Universidad Auto e Ca C.P. 25280, Saltillo, Coahuila, Mexico n y de Estudios Avanzados del IPN, Unidad Irapuato, Apartado Postal 629, Departamento de Biotecnología y Bioquímica, Centro de Investigacio C.P. 36821 Irapuato, Gto., Mexico c gico de Durango, Blvd. Felipe Pescador 1830 Ote., C.P. 34080, Durango, Dgo., Mexico Departamento de Ingenierías Química y Bioquímica, Instituto Tecnolo a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 2 December 2014 Received in revised form 19 September 2015 Accepted 21 September 2015 Available online 28 September 2015
The objective of this study was to determine the effect of supplemented prebiotics: inulin (I), oligofructose (O), agave fructans (A) and their mixtures in three levels, 20, 40 and 60 g prebiotics/kg puree on the physicochemical and sensorial properties of a dehydrated apple matrix (DAM), fruit leather type. A simplex-centroid design was used to formulate the different mixtures. After that, fructans were identified in the matrices using thin-layer chromatography and high-performance anion-exchange chromatography with pulsed amperometric detection and enzymatic kits. A descriptive quantitative method was used to determine sensory profile of the matrices. The sensory acceptability was measured by a 7-point hedonic scale. Matrices supplemented with solely A and O, were significantly smoother and more qualified in acceptability compared to the control. The behavior of DAM with inulin was different; it increased hardness and decreased acceptability. In general, mixtures of prebiotics had a synergistic effect on matrices hardness. The optimum formulation corresponded to the DAM supplemented with agave fructans, indicating that it is possible to obtain a fruit leather type product with prebiotic potential. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Prebiotics Functional food Fruit leather Sensory analysis
1. Introduction In recent years, human diet and its relationship with health has attained great importance. Therefore, consumption of functional foods provides an additional benefit to health, in addition to meeting the basic nutritional requirements, the demand of this type of food has increased among consumers to a large extent because of the natural interest of people to have a better life quality (Abdel-Salam, 2010; Ozen, Pons, & Tur, 2012). In 1984, Japan first introduced the term “functional foods”. After numerous studies on nutrition, fortification, sensory satisfaction and modulation of
* Corresponding author. lez-Herrera), omrutiaga@ E-mail addresses: [email protected] (S.M. Gonza ~ ones), [email protected] (C.N. Aguilar), aralui. yahoo.com (O.M. Rutiaga-Quin [email protected] (L.A. Ochoa-Martínez), [email protected] pez), raul.rodriguez@ (J.C. Contreras-Esquivel), [email protected] (M.G. Lo uadec.edu.mx (R. Rodríguez-Herrera). http://dx.doi.org/10.1016/j.lwt.2015.09.037 0023-6438/© 2015 Elsevier Ltd. All rights reserved.
physiological systems, a functional food was approved by the Japanese government as “food for specified health uses (FoSHU)” (Shimizu, 2012). However, this definition has evolved. The most current was emitted by the European Commission Concerted Action on Functional Food Science in Europe (FUFOSE), which defines functional foods as “a food can be regarded as ‘functional’ if it is satisfactorily demonstrated to beneficially effect one or more target functions in the body, beyond adequate nutritional effects, in a way that is relevant to either an improved state of health and well-being and/or reduction of risk of disease. Functional foods must remain as food and they must demonstrate their effects in amounts that can normally be expected to be consumed in the diet: they are not pills or capsules, but part of a normal food pattern” (Diplock et al., 1999; Ozen et al., 2012). Prebiotics can be considered as functional ingredients, because of their technological properties. They are included in products such as: yogurts, cereals, desserts, nutritional bars, beverages, and ice cream, among others (Gibson et al., 2010; Kolida & Gibson,
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2007; Ozen et al., 2012). The International Scientific Association for Probiotics and Prebiotics (ISAPP), defines prebiotics as “ingredients that selectively fermented, allow specific changes in the composition and/or activity of the gastrointestinal microbiota; thus, conferring a benefit on the health and well-being of the host” (Gibson et al., 2010). Inulin and oligofructose are fructans found widely distributed in nature as plant storage carbohydrates. They have a linear structure composed of fructose units linked to each other by b 2-1 bonds and meet the requirements to be considered prebiotics. Inulin and oligofructose have been studied and applied on a variety of foods, individually or mixed (Cardarelli, Saad, Gibson, & Vulevic, 2007; Devereux, Jones, McCormack, & Hunter, 2003; Tomaschunas et al., 2013). In recent years, there is a special interest on studying Agave fructans, which are reserve carbohydrates, found in Agave plants, and consist of complex structures highly, branched with links b 2-1 pez, 2006). in their majority and b2-6 (Mancilla-Margalli & Lo Although tests in vitro have revealed prebiotic potential (Gomez, pez & Urías-Silvas, Tuohy, Gibson, Klinder, & Costabile, 2010; Lo 2007; Moreno-Vilet et al., 2014), little application of agave fructans in food has been reported (Crispín-Isidro, Lobato-Calleros, Espinoza-Andrews, Alvarez-Ramirez, & Vernon-Carter, 2015). An important factor for a functional food to be accepted is the way in which it is offered. Dehydrated fruit-based snacks have the advantage of being perceived by consumers as healthy. Their sensory attributes are generally acceptable and have proven to be a ^go et al., 2013). In good carrier for prebiotics and probiotics (Re addition, incorporating prebiotics to products derived from fruits can enhance the beneficial effect on health and increase their € sz, Le, & Orsi, consumption (Matusek, Mere 2011; Sun-Waterhouse, 2011). The fruit leathers are products that can be consumed directly or cut into small parts for use in confectionery and bakery. They have a prolonged shelf life (Azeredo, Brito, Moreira, Farias, & Bruno, 2006). In this study, fruits with low commercial value (smaller than standard, having slight mechanical damage, deformed, among others) of apple cultivar “Red Delicious” were chosen for elaboration of a dehydrated apple matrix fruit leather type because of its low cost, underutilization, availability throughout most of the year, and health properties. The objective of this work was to determine the effect of agave fructans, inulin, oligofructose, and mixtures, on the technological and sensory properties of a dehydrated apple matrix fruit leather type.
samples were ground for 6 min using a kitchen blender (“Oster” xico) with the prebiotics diluted in 50 mL of a mod. 004093 NPO, Me solution of citric acid (10 g/L) according to the experimental design. A heat treatment at 75 C for 10 min was applied to the final blend. The final puree moisture was 818.89 g/kg puree. Then, 200 g of each formulation were poured in 20 35 cm metal trays lined with cellophane paper; the puree layer thickness was of 3 mm, according to digital Vernier. Then, samples were allowed to cool down at room temperature for 2 h up to 27 C before their processing. The drying process took place in a tray dryer (“POLINOX”, mod. SEM-2, xico) at 60 C for 5 h with an air velocity of 2 m/s. The matrices Me were considered adequately dry as soon as they achieved a moisture content of 150e180 g/kg, and a 0.5 mm of final thickness, they were vacuum packed in high density polyethylene bags and stored at room temperature. 2.2.2. Fructan extraction Fructans extraction from DAM was carried out in water at 80 C, 1 g of DAM sample was placed in 5 mL of water, and shaken for 15 min at 150 rpm. It was then filtered through Whatman paper No. 1. The extract was frozen at 20 C until analysis. 2.2.3. Fructan determination Presence of fructans in matrices was evaluated after using thin layer chromatography (TLC), and High-Performance Anion-Exchange Chromatography Pulsed Amperometric Detection (HPAECPAD) ion chromatograph Dionex ICS-3000 (Sunnyvale, CA. USA) and an enzymatic Kit (AOAC 999.03, AOAC 32.32). 2.2.3.1. (TLC) Thin layer chromatography. Solutions were prepared with a concentration of 20 mg/mL of the commercial prebiotics. Solutions with a concentration of 25 mg/mL of the DAM extracts, plus a DAM without prebiotics (CL) were used as control. Solution samples (1 mL) were applied on silica gel with aluminum support, simultaneously a standard with a mixture of glucose, fructose, sucrose, kestose (1K), nystose (1N) and 1-fructofuranosylnystose (DP5) were applied. Plaques were developed in a propanol-waterbutanol (12 mL: 4 mL: 3 mL) solvent system (Kanaya, Chiba, & Shimomura, 1978). For fructans visualization, plaques were sprayed with a reagent of aniline-diphenylamine-phosphoric acid in acetone (Anderson, Li, & Li, 2000). The reagent was prepared by dissolving diphenylamine (2 g) and aniline (2 mL) in acetone (100 mL) and carefully adding concentrated phosphoric acid (10 mL).
2. Materials and methods 2.1. Materials “Red Delicious” apples of low commercial value from Canatlan Durango, Mexico were used for matrices preparation. The tested commercial prebiotics were: Inulin (I) (Raftiline GR Beneo e Orafti, Tienen Belgium), Oligofructose (O) (Raftilose P95 Beneo e Orafti, Tienen Belgium) donated by MEGAFARMA S.A. DE CV. Mexico and agave fructans (A) Agave tequilana Weber (American Foods, Jalisco, Mexico), citric acid, glucose, fructose and sucrose from SigmaeAldrich (St. Louis, MO.) 2.2. Methods 2.2.1. Dehydrated apple matrix preparation Batches of dehydrated apple matrix (DAM) were prepared for each formulation. The process was modified and adapted for apple according to FAO-PRODAR (2014). A sample of 220 g of apples was washed. When necessary, damaged areas were removed, cut in halves, cored and subsequently it were slice in smaller pieces. Then,
2.2.3.2. High-performance anion-exchange chromatography pulsed amperometric detection (HPAEC-PAD). Solution of each commercial prebiotic was tested at a concentration of 0.5 mg/mL, and from the DAM extract at a concentration of 0.25 mg/mL were prepared using water with resistivity of 17 MU; then, were filtered through a 0.2 mm nylon membrane. Once filtered, the solutions were sonicated for 10 min and injected 25 mL in an ion chromatograph Dionex ICS-3000 (Sunnyvale, CA, USA.) with a guard-column CarboPac-PA100 (4 50 mm) and a CarboPac-PA-100 (4 250 mm) exchange column. A gradient of sodium acetate was used in NaOH 0.15 mol/L with a flow of 0.8 mL/min as follows: 0e5 min, 45 mmol/L NaOH; 5e60 min, 375 mmol/L sodium acetate; 60e65 min, 500 mmol/L sodium acetate 65e75 min, 45 mmol/L NaOH, at a column temperature of 25 C. The potentials applied by the detector's pulse were: (400 ms) E1, E2 (20 ms), E3 (20 ms), and E4 (60 ms) of þ0.1, 2.0, þ0.6 and 0.1 V, respectively (Mellado-Mojica & pez, 2012). Lo 2.2.3.3. Enzymatic quantification. The quantification was carried out using the commercial kit “Fructans” (AOAC 999.03, AOAC
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32.32), K-FRUC (Megazyme International Ireland, Ltd., Wicklow, Ireland) from the DAM extracts, following the manufacturer's instructions. All determinations were performed by triplicate.
Y ¼ b1 X1 þ b2 X2 þ b3 X3 þ b12 X1 X2þ þ b13 X1 X3 þ b23 X2 X3
2.2.4. Mechanical properties Hardness and stickiness were determined as follow; first, 4 3 cm DAM rectangles were cut and 3 of them were stacked for the test. In this step, a texture analyzer TA-XT2i (Texture Technology Corp, NY. USA) with a plaque with a drilling in the center and a cylindrical probe of 4 mm d (P/A) was used. The test speed was 1 mm/s, penetration distance was 2 mm by applying a force of 4.9 N.
where Y ¼ is the independent variable, b1, b2, b3, b12, b13, b23 y b123 y b123 are regression parameters, X1X2 X3 are prebiotics percentage in the mixture. Positive values in binary coefficients indicated synergistic effects and negative values indicated antagonism. Data was analyzed using the Statgraphic Centurion XVI® software. The prediction equations were obtained and surface plots were generated. In addition, an analysis of variance was conducted and when necessary, treatment means were compared using the Tukey multiple range test (p < 0.05).
2.2.5. Moisture content and water activity (aw) Water activity was determined using a Hygrolab water activity meter AW-DIO (ROTRONIC International, USA). Moisture content was determined using the AOAC 925.09 method and employing a ML-50 moisture analyzer (A & D Company, Limited. Tokyo, Japan.). 2.2.6. Sensory analysis A quantitative descriptive analysis was used. DAM attributes such as sweetness, hardness, acidity and stickiness were evaluated (Meilgaard, Civille, & Carr, 1999). In this analysis fifteen trained panelists participated as judges. Panelists were trained in three sessions of 50 min. They performed a quantitative descriptive analysis and received apple dehydrated matrix samples prepared with different characteristics as reference. Panelists were asked to read the instructions on the questionnaire and the meaning of each attribute was explained to panelists to avoid misinterpretation. Samples were evaluated in groups of 4 per session. They were codified with three digits and presented randomly. A categorized 7 point scale anchored with 'nothing' for number 1 and “very intense” for number 7 was used to measure attributes intensity. For evaluation of preference of the resulting formulations from the experimental design, 35 consumers (graduate students) who frequently consume such products (at least twice per week) participated. For this analysis a hedonic categorized 7-point scale was used where 1 means “I do not like it” and 7 means “I like it very much”. 2.2.7. Statistical analysis A simplex-centroid design for mixtures with three main components (Table 1) was applied to evaluate component interactions on DAM sensory properties and texture. The variables studied were: I, O and A prebiotics concentrations, treating mixtures as pseudo-components. The design was applied at three levels, 1 ¼ 20 g/kg, 2 ¼ 40 g/kg, and 3 ¼ 60 g/kg of puree. The experimental data were analyzed using the Scheffe equation.
Table 1 Mixtures composition in the dehydrated apple matrix formulated with inulin, oligofructose and agave fructans. Formulation
1 2 3 4 5 6 7
Component proportiona I
O
A
100 0 0 50 50 0 33.33
0 100 0 50 0 50 33.33
0 0 100 0 50 50 33.33
I ¼ Inulin, O ¼ Oligofructose A ¼ Agave fructans. a Coded values I þ O þ A ¼ 100.
þ b123 X1 X2 X3
3. Results and discussion 3.1. Fructan determination Presence of fructans in samples was evaluated through three analytical techniques. 3.1.1. Thin layer chromatography (TLC) Carbohydrate profiles of commercial fructans and DAM with different formulations are shown in Fig. 1. Carbohydrate profile of the commercial fructans (Fig. 1A) revealed that the tested agave fructans had high degree of polymerization. This is due to a sample in the plaque is concentrated almost in its totality at the application point. Unlike inulin (I) which showed fructans of different polymerization degree, coinciding with those results pez, Mancilla-Margalli, and Mendoza-Diaz (2003) reported by Lo pez-Medina, and Lo pez (2009). Presence of and Mellado-Mojica, Lo fructans with low degree of polymerization is typical of oligofructose (O), mainly of the Fn series (without glucose units) (Kelly, 2008). Fig. 1B shows the carbohydrates profile of DAM. Spots corresponding to glucose, fructose and sucrose, typical of apple components appeared in all samples. Spots corresponding to commercial prebiotics were observed in all the samples. In the control matrix (CL) fructans spots do not appear. The thin layer chromatography has been used successfully for analysis of fructooligosaccharides even in complex biological samples (Reiffov a& Nemcov a, 2006). 3.1.2. High-performance anion-exchange chromatography pulsed amperometric detection (HPAEC-PAD) In Fig. 2A the characteristic peaks of inulin are shown, where the time of retention was from 14.5 to 60 min, are characterized by a higher proportion of the Gn serie (a glucose molecule), 1 K ¼ 1kestose, F3 ¼ inulotriose, 1N ¼ 1-nystose, F4 ¼ inulotetraose, DP5 ¼ 1-fructofuranosylnystose, and F5 ¼ Inulopentaose. Presence of inulin in extract of DAM supplemented with inulin is shown in Fig. 2B, where peaks and retention time were identified. Fig. 2C corresponds to DAM CL, where presence of fructans was not observed. This behavior was similar in all formulations (data not shown). 3.1.3. Enzymatic quantification of fructans (Kit MEGAZYME) The final fructans content in the DAM were level 1 ¼ 70.4, level 2 ¼ 110.02 and level 3 ¼ 150.4 g/kg of DAM. According to these results, an approximate portion of 35 g daily of DAM in any of the levels studied, would cover the recommendation of suggested daily intake of 2e5 g (Beneo Orafti) (Araújo, Carvalho, Leandro, Furtado, & Moraes, 2010; Roberfroid, 2005; VolpiniRapina, Ruriko, & Conti-Silva, 2012; ). Fructans concentration increased because of dehydration process applied on the
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Fig. 1. Thin-Layer chromatography of commercial prebiotics solutions (1A), and extracts of dehydrated apple matrices (1B). DP ¼ degree of polymerization, A ¼ agave fructans; I ¼ inulin, O ¼ oligofructose STD ¼ standards, G ¼ Glucose, F ¼ fructose, S ¼ sucrose, K ¼ 1-kestose, N ¼ 1-nystose and DP5 ¼ 1-fructofuranosylnystose); CL ¼ control matrix without prebiotics. Stationary phase: silica gel plates with aluminum support; mobile phase: propanol-agua-butanol (12 mL : 4 mL : 3 mL); detection reagent: anilineediphenylamineephosphoric acid in acetone; volume of sample 1 mL.
matrices. Volpini-Rapina et al. (2012) evaluated addition of inulin and oligofructose/inulin, on orange cake by the same method. Content of fructans were 90 and 83 g/kg respectively. The supplemented fructans were present in matrices and resisted processing conditions. Results in the present study are consistent with those reported by Huebner, Wehling, Parkhurst, and Hutkins (2008), who carried out a prebiotic activity essay following exposure commercial fructans in solution at different pH and temperatures conditions. They also discovered that significant changes occurred when low pH and temperatures above 85 C were combined. Conditions used in the process of DAM in
this study, were below this temperature. The effect of temperature and water activity has been only evaluated on fructans powder (Espinosa-Andrews & Urías-Silvas, 2012). 3.2. Moisture content, aw, and mechanical properties Physicochemical and mechanical properties of DAM are shown in Table 2, where it is observed that level 3 showed significant differences. Moisture content of DAM was not affected by relationship or type of fructans according to control DAM, as it was found within the range of moisture for this type of food. However,
Fig. 2. High-Performance Anion Exchange Chromatography-Pulsed Amperometric Detection. Chromatographics profiles of fructans of commercial inulin (2A), extract of dehydrated apple matrix with inulin (2B) and extract of dehydrated apple matrix without inulin (2C). DP ¼ degree of polymerization, F ¼ fructan serie without glucose molecule, K ¼ 1-kestose, F3 ¼ Inulotriose, N ¼ 1-nystose and DP5 ¼ 1-fructofuranosylnystose. Column: CarboPac-PA100 (4 250 mm); mobile phase: gradient of sodium acetate, in 0.15 mol/L NaOH; flow: 0.8 mL/min; volume of sample 25 mL.
lez-Herrera et al. / LWT - Food Science and Technology 65 (2016) 1059e1065 S.M. Gonza Table 2 Physicochemical and mechanical properties for each formulation of dehydrated apple matrix supplemented with prebiotics. Formulation
1 2 3 4 5 6 7 CL Pooled SD
Physicochemical properties
Mechanical properties
Moisture content (g/kg)
aw
Hardness N
Stickiness N
156.0a 163.0a 178.0a 188.0a 165.0a 160.0a 166.0a 169.0a
0.563c 0.540b 0.696e 0.670d 0.478a 0.544b 0.479a 0.506b
7.1d 4.0b 2.4a 5.0c 4.5bc 6.2d 6.7d 4.1bc
0.358ab 0.460bc 0.596bc 0.653de 0.872f 0.785ef 0.374ab 0.268a
15.6
0.004
1.11
0.093
Different letters within the columns indicate different means (p < 0.05, n ¼ 3). CL ¼ dehydrated apple matrix without prebiotics. SD ¼ Standard deviation.
significant differences between treatments and the control for aw were found. The highest value was observed in the formulation 3 that was supplemented only with agave fructans. The formulation 3 (A) presented the lowest hardness value, statistically different from the other studied prebiotics and control. These results can be related to the aw. The highest value corresponds to formulation 3 (A). This may be because of the technological properties of the agave fructans, which have a complex structure. They are different to the inulin-type fructans. It has been reported that their behavior is dependent on aw and temperature values when they have been studied without being applied in food (Espinosa-Andrews & Urías-Silvas, 2012). The highest hardness value correspondent to formulation 1 (I), is consistent with that reported for other types of food matrixes, in which inulin or mixed inulin/oligofructose was applied, such as ice cream, chocolate and cake (El-Nagar, Clowes, Tudorica, Kuri, & Brennan, 2002; Farzanmehr & Abbasi, 2009; Volpini-Rapina et al., 2012). Stickiness of all treatments was significantly higher compared to control (Table 2). Several authors have reported that the increase in the stickiness of different foods with the addition of fructans, which can be related to the formation of a viscous gel matrix because of the gelling properties along with the ability to bind water of fructans such as inulin (El-Nagar et al., 2002; Farzanmehr & Abbasi, 2009; Volpini-Rapina et al., 2012). Espinosa-Andrews and UríasSilvas (2012) found that at water activities around 0.6, agave fructans caked and change to a sticky material, perhaps this is the cause of the stickiness in the DAM, but further studies would be required to confirm this.
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Formulations 1 and 7 (I and IOA) presented the lowest values of stickiness, and it is associated with high values of hardness. The characteristics presented in the DAM of agave fructans were different and showed a technological potential for commercial development of a product apple leather type, supplemented with these fructans. 3.3. Sensory analysis Intensity of sensory attributes and overall acceptability is shown in Table 3. From the results it was observed that the panel did not perceived any significative difference in the attributes such as acidity, sweetness, and stickiness between formulations and the control. However, hardness intensity of formulation 3 (A) was statistically different from the other formulations and control, having the lowest value. Among the other formulations, there was no difference in the perception of panel regarding hardness. In terms of general acceptability of DAM, formulation 3 (A) was the best qualified, statistically different from formulation 1 (I) and control. Sensory evaluation results may be related to data obtained from measurements of the aw and hardness, where formulation 3 (A) was the most accepted. It presented the lower hardness and the higher water activity. This suggests that agave fructans, incorporated in the matrix leather type, gave mechanical, physicochemical, and sensory properties suitable for this type of product. The formulation 1 (I) had the highest hardness in both kinds of measurements, instrumental and sensory evaluation. This effect has been reported in different types of food matrices such as ice cream, cake and chocolate (El-Nagar et al., 2002; Farzanmehr & Abbasi, 2009; Volpini-Rapina et al., 2012). However, in other foods such as cheeses and cured meats, hardness decreases as addition of inulin increases (Menegas, Pimentel, Garcia, & Prudencio, 2013; Salvatore, Pes, Mazzarello, & Pirisi, 2014). These results indicate that interactions are food matrix-depended. 3.4. Mathematical model, equations and component effects The equations generated from sensory attributes and mechanical properties of different formulations are presented in Table 4. Only those equations where evaluated parameters had significant influence on matrix components are shown. Special linear (data not shown), quadratic (data not shown) and cubic models were evaluated; the best fit for all variables was for the special cubic model. Fig. 3 shows the contour graphs, illustrating the effect of mixtures of fructans on DAM mechanical and sensorial parameters. In Fig. 3A, formulation 7 (inulin-oligofructose-agave fructans) and
Table 3 Sensory characteristicsa and overall acceptabilityb for each formulation of dehydrated apple matrix supplemented with prebiotics. Formulation
Trained panel
Untrained panel
Sourness
Sweetness
Stickiness
Hardness
Overall acceptability
1 2 3 4 5 6 7 CL
3.2a 3.4a 3.5a 3.1a 3.8a 3.4a 3.1a 3.6a
4.3a 4.2a 4.2a 3.4a 3.4a 3.2a 3.8a 3.8a
3.1a 2.6a 2.8a 2.9a 2.9a 2.2a 3.2a 3.1a
4.5a 3.4abc 2.5c 3.7ab 4.1ab 3.8ab 4.3ab 3.7ab
3.9bc 5.1ab 5.7a 4.4abc 4.7abc 3.8bc 3.3c 4.2bc
Poleed SD
1.34
1.17
1.30
1.54
1.30
Different letters within the columns indicate different means (p < 0.05 n ¼ 3). SD ¼ Standard deviation. CL ¼ dehydrated apple matrix without prebiotics. a Scale 1 ¼ Nothing 7 ¼ Very intense. b 1 ¼ I did not like it 7 ¼ I like it very much.
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Table 4 Predicted equations for experimental data of dehydrated apple matrix formulations supplemented with prebiotics with significant influence.
Sensory parameter Acceptability Hardness Mechanical properties Stickiness Hardness
Equation
R2
Y ¼ 3.93*I þ 4.8*O þ 5.6*A þ 0.93*I*O 0.93*I*A 5.06*O*A 12.99*I*O*A Y ¼ 4.53*I þ 2.6*O þ 2.53*A 1.73*I*O þ 2.13*I*A þ 1.2*O*A þ 27.00*I*O*A
0.749 0.890
Y ¼ 0.370*I þ 0.435*O þ 0.66*A þ 0.942*I*O þ 0.982*I*A þ 0.814*O*A-10.190*I*O*A Y ¼ 7.10*I þ 4.07*O þ 2.52A 3.49*I*O 1.37*I*A þ 12.72*O*A þ 31.46*I*O*A
0.826 0.956
I ¼ Inulin, O ¼ Oligofructose, A ¼ Agave fructans (p < 0.05 n ¼ 3).
Fig. 3. Ternary contour plots of effects of supplementation of inulin, oligofructose an agave fructans on mechanical hardness (3A), mechanical stickiness (3B), sensory hardness (3C), and overall acceptability (3D) of the dehydrated apple matrix.
formulation 6 (oligofructose-agave fructans) interaction, had a significant influence on mechanical hardness, as seen in the high values of coefficients (Table 4), indicating a synergistic effect of these mixtures. The highest hardness value is located in the inulin vertex. This behavior matches the sensory properties in relation to formulation 7, which indicates that while the inulin ratio increases, hardness also increases. In the formulation 6, hardness was not perceived by the panel (Fig. 3C), but interaction inulin-agave fructans inversely affected general acceptability of the product (Fig. 3D), showing high values of coefficients in mixtures (Table 4) and an antagonistic effect, suggests a significant influence of this attribute. Stickiness is also manifested in inverse relationship to hardness, being lower in inulin-oligofructose- agave fructans mixture and the inulin vertex. The hardness values tend to be lower in the agave fructans-inulin and agave fructans-oligofructose mixtures as they approach the agave fructans and inulin vertices (Fig. 3A). As a result, it can be considered that interaction of these mixtures with high proportions of agave fructans or oligofructose have an antagonistic effect for this property as it is confirmed by the coefficients (Table 4), in such a way that these DAM have a softer texture, reflecting a higher acceptability value (Fig. 3D). In general, mixtures of fructans did not have a desirable impact on the acceptability of the matrices. Agave fructans and oligofructose
applied individually give matrices with desirable texture features. The results obtained from analysis of the model reveal that the optimal formulation based on acceptability for this product, is to use prebiotics individually. 4. Conclusions This study shows that the addition of mixtures of agave fructans, inulin and oligofructose changed the mechanical properties of hardness and stickiness of dehydrated apple matrix in relation to the control matrix, independently of the prebiotic type used in the mixture. The above findings reflected a decrease in consumer acceptability. Supplementation with only agave fructans to the matrix was very effective to improve the texture. Consumer acceptability was higher than those of the control matrix and the other evaluated formulations. From the above results, it has been demonstrated that the potential of agave fructans in these type of products extends the possibility to apply them in other processed food matrices. More studies are needed to verify the prebiotic potential. Acknowledgments Authors express their deep gratitude to M.C. Ma. de Jesus
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Alvarado Balleza for the excellent technical assistance. SMGH thanks CONACYT, Mexico, for her doctoral scholarship (55354). References Abdel-Salam, A. M. (2010). Functional food: hopefulness to good health. American Journal of Food Technology, 5, 86e99. Anderson, K., Li, S. C., & Li, Y. T. (2000). Diphenylamineanilinephosphoric acid reagent, a versatile spray reagent for revealing glycoconjugates on thin-layer chromatography plates. Analytical Biochemistry, 287, 337e339. Araújo, E. A., Carvalho, A. F., Leandro, E. S., Furtado, M. M., & Moraes, C. A. (2010). Development of a symbiotic cottage cheese added with Lactobacillus delbrueckii UFV H2b20 and inulin. Journal of Functional Foods, 2, 85e89. Azeredo, H., Brito, E., Moreira, G., Farias, V., & Bruno, L. (2006). Effect of drying and storage time on the physico-chemical properties of mango leathers. International Journal of Food Science and Technology, 41, 635e638. Cardarelli, H. R., Saad, S. M. I., Gibson, G. R., & Vulevic, J. (2007). Functional petitsuisse cheese: measure of the prebiotic effect. Anaerobe, 13, 200e207. Crispín-Isidro, G., Lobato-Calleros, C., Espinoza-Andrews, H., Alvarez-Ramirez, J., & Vernon-Carter, E. J. (2015). Effect of inulin and agave fructans addition on the rheological, microstructural and sensory properties of reduced-fat stirred yogurt. LWT Food Science and Technology, 62, 438e444. Devereux, H. M., Jones, G. P., McCormack, L., & Hunter, W. C. (2003). Consumer acceptability of low fat foods containing inulin and oligofructose. Journal of Food Science, 68, 1850e1854. Diplock, A. T., Aggett, P., Ashwell, M., Bornet, F., Fern, E., & Roberfroid, M. (1999). Scientific concepts of functional foods in Europe: consensus document. British Journal of Nutrition, 9(81), 1e27. El-Nagar, G., Clowes, G., Tudorica, C. M., Kuri, V., & Brennan, C. S. (2002). Rheological quality and stability of yog-ice cream with added inulin. International Journal of Dairy Technology, 55, 89e93. Espinosa-Andrews, H., & Urías-Silvas, J. E. (2012). Thermal properties of agave fructans (Agave tequilana Weber var. Azul). Carbohydrate Polymers, 87, 2671e2676. FAO-PRODAR (Food and Agriculture Organization of the United Nations). (2014). Fichas t ecnicas: Procesados de frutas (pp. 58e61). Available at: http://www.fao. org/in-action/inpho/library. Consulted July 27, 2015. Farzanmehr, H., & Abbasi, S. (2009). Effects of inulin and bulking agents on some physicochemical, textural and sensory properties of milk chocolate. Journal of Texture Studies, 40, 536e553. Gibson, R., Scott, K. P., Rastall, R. A., Tuohy, K. M., Hotchkiss, A., DubertFerrandon, A. … Buddington, R. (2010). Dietary prebiotics: current status and new definition. Food Science and Technology Bulletin: Functional Foods, 7, 1e19. Gomez, E., Tuohy, K. M., Gibson, G. R., Klinder, A., & Costabile, A. (2010). In vitro evaluation of the fermentation properties and potential prebiotic activity of agave fructans. Journal of Applied Microbiology, 108, 2114e2121. Huebner, J., Wehling, R. L., Parkhurst, A., & Hutkins, R. W. (2008). Effect of processing conditions on the prebiotic activity of commercial prebiotics. International Dairy Journal, 18, 287e293. Kanaya, K., Chiba, S., & Shimomura, T. (1978). Thin-layer chromatography of linear oligosaccharides. Agricultural and Biological Chemistry, 42, 1947e1948. Kelly, G. N. D. (2008). Inulin-type prebiotics: a review. Alternative Medicine Review, 13, 315e329.
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Kolida, S., & Gibson, G. R. (2007). Prebiotic capacity of inulin-type fructans. Journal of Nutrition, 137, 2503Se2506S. pez, M. G., Mancilla-Margalli, N. A., & Mendoza-Diaz, G. (2003). Molecular Lo structures of fructans from Agave tequilana Weber var. azul. Journal of Agricultural and Food Chemistry, 51, 7835e7840. pez, M. G., & Urías-Silvas, J. E. (2007). Agave fructans as prebiotics. Recent AdLo vances in Fructooligosaccharides Research, 1e14. pez, M. G. (2006). Water-soluble carbohydrates and Mancilla-Margalli, N. A., & Lo fructan structure patterns from Agave and Dasylirion species. Journal of Agricultural and Food Chemistry, 54, 7832e7839. € sz, P., Le, T. K. D., & Orsi, Matusek, A., Mere F. (2011). Fructooligosaccharide degradation in apple pulp matrix. Acta Alimentaria, 40, 182e193. Meilgaard, M., Civille, G. V., & Carr, B. T. (1999). Sensory evaluation techniques (3rd ed.). Boca Raton: CRC Press. pez, M. G. (2012). Fructan metabolism in A. tequilana Weber Mellado-Mojica, E., & Lo blue variety along its developmental cycle in the field. Journal of Agricultural and Food Chemistry, 60, 11704e11713. pez-Medina, T. L., & Lo pez, M. G. (2009). Developmental Mellado-Mojica, E., Lo variation in Agave tequilana Weber var. Azul stem carbohydrates. Dynamic Biochemistry, Process Biotecnology and Molecular Biology, 3, 34e39. Menegas, L. Z., Pimentel, T. C., Garcia, S., & Prudencio, S. H. (2013). Dry-fermented chicken sausage produced with inulin and corn oil: physicochemical, microbiological, and textural characteristics and acceptability during storage. Meat Science, 93, 501e506. Moreno-Vilet, L., Garcia-Hernandez, M. H., Delgado-Portales, R. E., CorralFernandez, N. E., Cortez-Espinosa, N., Ruiz-Cabrera, M. A., et al. (2014). In vitro assessment of agave fructans (Agave salmiana) as prebiotics and immune system activators. International Journal of Biological Macromolecules, 63, 181e187. Ozen, A. E., Pons, A., & Tur, J. A. (2012). Worldwide consumption of functional foods: a systematic review. Nutrition Reviews, 70, 472e481. ^go, A., Freixo, R., Silva, J., Gibbs, P., Morais, A. M. M. B., & Teixeira, P. (2013). Re A functional dried fruit matrix incorporated with probiotic strains: Lactobacillus plantarum and Lactobacillus kefir. Focusing on Modern Food Industry, 2, 138e143. , K., & Nemcova , R. (2006). Thin-layer chromatography analysis of fructooReiffova ligosaccharides in biological samples. Journal of Chromatography A, 1110, 214e221. Roberfroid, M. (2005). Introducing inulin-type fructans. British Journal of Nutrition, 93, 513e525. Salvatore, E., Pes, M., Mazzarello, V., & Pirisi, A. (2014). Replacement of fat with long-chain inulin in a fresh cheese made from caprine milk. International Dairy Journal, 34, 1e5. Shimizu, M. (2012). Functional food in Japan: current status and future of gutmodulating food. Journal of Food and Drug Analysis, 20, 213e216. Sun-Waterhouse, D. (2011). The development of fruit-based functional foods targeting thehealth and wellness market: a review. International Journal of Food Science and Technology, 46, 899e920. €rb, R., Fischer, J., Ko €hn, E., Jo €rg Hinrichs, J., & BuschTomaschunas, M., Zo Stockfisch, M. (2013). Changes in sensory properties and consumer acceptance of reduced fat pork lyon-style and liver sausages containing inulin and citrus fiber as fat replacers. Meat Science, 95, 629e640. Volpini-Rapina, L. F., Ruriko, S. F., & Conti-Silva, A. C. (2012). Sensory profile and preference mapping of orange cakes with addition of prebiotics inulin and oligofructose. LWT e Food Science and Technology, 48, 37e42.
Contents lists available at ScienceDirect
LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt
Dehydrated apple matrix supplemented with agave fructans, inulin, and oligofructose lez-Herrera a, Olga Miriam Rutiaga-Quin ~ ones c, Silvia Marina Gonza bal Noe Aguilar a, Luz Araceli Ochoa-Martínez c, Juan Carlos Contreras-Esquivel a, Cristo pez b, Raúl Rodríguez-Herrera a, * Mercedes G. Lo rdenas V. s/n. Col. República Ote, noma de Coahuila, Blvd. V. Carranza e Ing. Jos Food Research Department, School of Chemistry, Universidad Auto e Ca C.P. 25280, Saltillo, Coahuila, Mexico n y de Estudios Avanzados del IPN, Unidad Irapuato, Apartado Postal 629, Departamento de Biotecnología y Bioquímica, Centro de Investigacio C.P. 36821 Irapuato, Gto., Mexico c gico de Durango, Blvd. Felipe Pescador 1830 Ote., C.P. 34080, Durango, Dgo., Mexico Departamento de Ingenierías Química y Bioquímica, Instituto Tecnolo a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 2 December 2014 Received in revised form 19 September 2015 Accepted 21 September 2015 Available online 28 September 2015
The objective of this study was to determine the effect of supplemented prebiotics: inulin (I), oligofructose (O), agave fructans (A) and their mixtures in three levels, 20, 40 and 60 g prebiotics/kg puree on the physicochemical and sensorial properties of a dehydrated apple matrix (DAM), fruit leather type. A simplex-centroid design was used to formulate the different mixtures. After that, fructans were identified in the matrices using thin-layer chromatography and high-performance anion-exchange chromatography with pulsed amperometric detection and enzymatic kits. A descriptive quantitative method was used to determine sensory profile of the matrices. The sensory acceptability was measured by a 7-point hedonic scale. Matrices supplemented with solely A and O, were significantly smoother and more qualified in acceptability compared to the control. The behavior of DAM with inulin was different; it increased hardness and decreased acceptability. In general, mixtures of prebiotics had a synergistic effect on matrices hardness. The optimum formulation corresponded to the DAM supplemented with agave fructans, indicating that it is possible to obtain a fruit leather type product with prebiotic potential. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Prebiotics Functional food Fruit leather Sensory analysis
1. Introduction In recent years, human diet and its relationship with health has attained great importance. Therefore, consumption of functional foods provides an additional benefit to health, in addition to meeting the basic nutritional requirements, the demand of this type of food has increased among consumers to a large extent because of the natural interest of people to have a better life quality (Abdel-Salam, 2010; Ozen, Pons, & Tur, 2012). In 1984, Japan first introduced the term “functional foods”. After numerous studies on nutrition, fortification, sensory satisfaction and modulation of
* Corresponding author. lez-Herrera), omrutiaga@ E-mail addresses: [email protected] (S.M. Gonza ~ ones), [email protected] (C.N. Aguilar), aralui. yahoo.com (O.M. Rutiaga-Quin [email protected] (L.A. Ochoa-Martínez), [email protected] pez), raul.rodriguez@ (J.C. Contreras-Esquivel), [email protected] (M.G. Lo uadec.edu.mx (R. Rodríguez-Herrera). http://dx.doi.org/10.1016/j.lwt.2015.09.037 0023-6438/© 2015 Elsevier Ltd. All rights reserved.
physiological systems, a functional food was approved by the Japanese government as “food for specified health uses (FoSHU)” (Shimizu, 2012). However, this definition has evolved. The most current was emitted by the European Commission Concerted Action on Functional Food Science in Europe (FUFOSE), which defines functional foods as “a food can be regarded as ‘functional’ if it is satisfactorily demonstrated to beneficially effect one or more target functions in the body, beyond adequate nutritional effects, in a way that is relevant to either an improved state of health and well-being and/or reduction of risk of disease. Functional foods must remain as food and they must demonstrate their effects in amounts that can normally be expected to be consumed in the diet: they are not pills or capsules, but part of a normal food pattern” (Diplock et al., 1999; Ozen et al., 2012). Prebiotics can be considered as functional ingredients, because of their technological properties. They are included in products such as: yogurts, cereals, desserts, nutritional bars, beverages, and ice cream, among others (Gibson et al., 2010; Kolida & Gibson,
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2007; Ozen et al., 2012). The International Scientific Association for Probiotics and Prebiotics (ISAPP), defines prebiotics as “ingredients that selectively fermented, allow specific changes in the composition and/or activity of the gastrointestinal microbiota; thus, conferring a benefit on the health and well-being of the host” (Gibson et al., 2010). Inulin and oligofructose are fructans found widely distributed in nature as plant storage carbohydrates. They have a linear structure composed of fructose units linked to each other by b 2-1 bonds and meet the requirements to be considered prebiotics. Inulin and oligofructose have been studied and applied on a variety of foods, individually or mixed (Cardarelli, Saad, Gibson, & Vulevic, 2007; Devereux, Jones, McCormack, & Hunter, 2003; Tomaschunas et al., 2013). In recent years, there is a special interest on studying Agave fructans, which are reserve carbohydrates, found in Agave plants, and consist of complex structures highly, branched with links b 2-1 pez, 2006). in their majority and b2-6 (Mancilla-Margalli & Lo Although tests in vitro have revealed prebiotic potential (Gomez, pez & Urías-Silvas, Tuohy, Gibson, Klinder, & Costabile, 2010; Lo 2007; Moreno-Vilet et al., 2014), little application of agave fructans in food has been reported (Crispín-Isidro, Lobato-Calleros, Espinoza-Andrews, Alvarez-Ramirez, & Vernon-Carter, 2015). An important factor for a functional food to be accepted is the way in which it is offered. Dehydrated fruit-based snacks have the advantage of being perceived by consumers as healthy. Their sensory attributes are generally acceptable and have proven to be a ^go et al., 2013). In good carrier for prebiotics and probiotics (Re addition, incorporating prebiotics to products derived from fruits can enhance the beneficial effect on health and increase their € sz, Le, & Orsi, consumption (Matusek, Mere 2011; Sun-Waterhouse, 2011). The fruit leathers are products that can be consumed directly or cut into small parts for use in confectionery and bakery. They have a prolonged shelf life (Azeredo, Brito, Moreira, Farias, & Bruno, 2006). In this study, fruits with low commercial value (smaller than standard, having slight mechanical damage, deformed, among others) of apple cultivar “Red Delicious” were chosen for elaboration of a dehydrated apple matrix fruit leather type because of its low cost, underutilization, availability throughout most of the year, and health properties. The objective of this work was to determine the effect of agave fructans, inulin, oligofructose, and mixtures, on the technological and sensory properties of a dehydrated apple matrix fruit leather type.
samples were ground for 6 min using a kitchen blender (“Oster” xico) with the prebiotics diluted in 50 mL of a mod. 004093 NPO, Me solution of citric acid (10 g/L) according to the experimental design. A heat treatment at 75 C for 10 min was applied to the final blend. The final puree moisture was 818.89 g/kg puree. Then, 200 g of each formulation were poured in 20 35 cm metal trays lined with cellophane paper; the puree layer thickness was of 3 mm, according to digital Vernier. Then, samples were allowed to cool down at room temperature for 2 h up to 27 C before their processing. The drying process took place in a tray dryer (“POLINOX”, mod. SEM-2, xico) at 60 C for 5 h with an air velocity of 2 m/s. The matrices Me were considered adequately dry as soon as they achieved a moisture content of 150e180 g/kg, and a 0.5 mm of final thickness, they were vacuum packed in high density polyethylene bags and stored at room temperature. 2.2.2. Fructan extraction Fructans extraction from DAM was carried out in water at 80 C, 1 g of DAM sample was placed in 5 mL of water, and shaken for 15 min at 150 rpm. It was then filtered through Whatman paper No. 1. The extract was frozen at 20 C until analysis. 2.2.3. Fructan determination Presence of fructans in matrices was evaluated after using thin layer chromatography (TLC), and High-Performance Anion-Exchange Chromatography Pulsed Amperometric Detection (HPAECPAD) ion chromatograph Dionex ICS-3000 (Sunnyvale, CA. USA) and an enzymatic Kit (AOAC 999.03, AOAC 32.32). 2.2.3.1. (TLC) Thin layer chromatography. Solutions were prepared with a concentration of 20 mg/mL of the commercial prebiotics. Solutions with a concentration of 25 mg/mL of the DAM extracts, plus a DAM without prebiotics (CL) were used as control. Solution samples (1 mL) were applied on silica gel with aluminum support, simultaneously a standard with a mixture of glucose, fructose, sucrose, kestose (1K), nystose (1N) and 1-fructofuranosylnystose (DP5) were applied. Plaques were developed in a propanol-waterbutanol (12 mL: 4 mL: 3 mL) solvent system (Kanaya, Chiba, & Shimomura, 1978). For fructans visualization, plaques were sprayed with a reagent of aniline-diphenylamine-phosphoric acid in acetone (Anderson, Li, & Li, 2000). The reagent was prepared by dissolving diphenylamine (2 g) and aniline (2 mL) in acetone (100 mL) and carefully adding concentrated phosphoric acid (10 mL).
2. Materials and methods 2.1. Materials “Red Delicious” apples of low commercial value from Canatlan Durango, Mexico were used for matrices preparation. The tested commercial prebiotics were: Inulin (I) (Raftiline GR Beneo e Orafti, Tienen Belgium), Oligofructose (O) (Raftilose P95 Beneo e Orafti, Tienen Belgium) donated by MEGAFARMA S.A. DE CV. Mexico and agave fructans (A) Agave tequilana Weber (American Foods, Jalisco, Mexico), citric acid, glucose, fructose and sucrose from SigmaeAldrich (St. Louis, MO.) 2.2. Methods 2.2.1. Dehydrated apple matrix preparation Batches of dehydrated apple matrix (DAM) were prepared for each formulation. The process was modified and adapted for apple according to FAO-PRODAR (2014). A sample of 220 g of apples was washed. When necessary, damaged areas were removed, cut in halves, cored and subsequently it were slice in smaller pieces. Then,
2.2.3.2. High-performance anion-exchange chromatography pulsed amperometric detection (HPAEC-PAD). Solution of each commercial prebiotic was tested at a concentration of 0.5 mg/mL, and from the DAM extract at a concentration of 0.25 mg/mL were prepared using water with resistivity of 17 MU; then, were filtered through a 0.2 mm nylon membrane. Once filtered, the solutions were sonicated for 10 min and injected 25 mL in an ion chromatograph Dionex ICS-3000 (Sunnyvale, CA, USA.) with a guard-column CarboPac-PA100 (4 50 mm) and a CarboPac-PA-100 (4 250 mm) exchange column. A gradient of sodium acetate was used in NaOH 0.15 mol/L with a flow of 0.8 mL/min as follows: 0e5 min, 45 mmol/L NaOH; 5e60 min, 375 mmol/L sodium acetate; 60e65 min, 500 mmol/L sodium acetate 65e75 min, 45 mmol/L NaOH, at a column temperature of 25 C. The potentials applied by the detector's pulse were: (400 ms) E1, E2 (20 ms), E3 (20 ms), and E4 (60 ms) of þ0.1, 2.0, þ0.6 and 0.1 V, respectively (Mellado-Mojica & pez, 2012). Lo 2.2.3.3. Enzymatic quantification. The quantification was carried out using the commercial kit “Fructans” (AOAC 999.03, AOAC
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32.32), K-FRUC (Megazyme International Ireland, Ltd., Wicklow, Ireland) from the DAM extracts, following the manufacturer's instructions. All determinations were performed by triplicate.
Y ¼ b1 X1 þ b2 X2 þ b3 X3 þ b12 X1 X2þ þ b13 X1 X3 þ b23 X2 X3
2.2.4. Mechanical properties Hardness and stickiness were determined as follow; first, 4 3 cm DAM rectangles were cut and 3 of them were stacked for the test. In this step, a texture analyzer TA-XT2i (Texture Technology Corp, NY. USA) with a plaque with a drilling in the center and a cylindrical probe of 4 mm d (P/A) was used. The test speed was 1 mm/s, penetration distance was 2 mm by applying a force of 4.9 N.
where Y ¼ is the independent variable, b1, b2, b3, b12, b13, b23 y b123 y b123 are regression parameters, X1X2 X3 are prebiotics percentage in the mixture. Positive values in binary coefficients indicated synergistic effects and negative values indicated antagonism. Data was analyzed using the Statgraphic Centurion XVI® software. The prediction equations were obtained and surface plots were generated. In addition, an analysis of variance was conducted and when necessary, treatment means were compared using the Tukey multiple range test (p < 0.05).
2.2.5. Moisture content and water activity (aw) Water activity was determined using a Hygrolab water activity meter AW-DIO (ROTRONIC International, USA). Moisture content was determined using the AOAC 925.09 method and employing a ML-50 moisture analyzer (A & D Company, Limited. Tokyo, Japan.). 2.2.6. Sensory analysis A quantitative descriptive analysis was used. DAM attributes such as sweetness, hardness, acidity and stickiness were evaluated (Meilgaard, Civille, & Carr, 1999). In this analysis fifteen trained panelists participated as judges. Panelists were trained in three sessions of 50 min. They performed a quantitative descriptive analysis and received apple dehydrated matrix samples prepared with different characteristics as reference. Panelists were asked to read the instructions on the questionnaire and the meaning of each attribute was explained to panelists to avoid misinterpretation. Samples were evaluated in groups of 4 per session. They were codified with three digits and presented randomly. A categorized 7 point scale anchored with 'nothing' for number 1 and “very intense” for number 7 was used to measure attributes intensity. For evaluation of preference of the resulting formulations from the experimental design, 35 consumers (graduate students) who frequently consume such products (at least twice per week) participated. For this analysis a hedonic categorized 7-point scale was used where 1 means “I do not like it” and 7 means “I like it very much”. 2.2.7. Statistical analysis A simplex-centroid design for mixtures with three main components (Table 1) was applied to evaluate component interactions on DAM sensory properties and texture. The variables studied were: I, O and A prebiotics concentrations, treating mixtures as pseudo-components. The design was applied at three levels, 1 ¼ 20 g/kg, 2 ¼ 40 g/kg, and 3 ¼ 60 g/kg of puree. The experimental data were analyzed using the Scheffe equation.
Table 1 Mixtures composition in the dehydrated apple matrix formulated with inulin, oligofructose and agave fructans. Formulation
1 2 3 4 5 6 7
Component proportiona I
O
A
100 0 0 50 50 0 33.33
0 100 0 50 0 50 33.33
0 0 100 0 50 50 33.33
I ¼ Inulin, O ¼ Oligofructose A ¼ Agave fructans. a Coded values I þ O þ A ¼ 100.
þ b123 X1 X2 X3
3. Results and discussion 3.1. Fructan determination Presence of fructans in samples was evaluated through three analytical techniques. 3.1.1. Thin layer chromatography (TLC) Carbohydrate profiles of commercial fructans and DAM with different formulations are shown in Fig. 1. Carbohydrate profile of the commercial fructans (Fig. 1A) revealed that the tested agave fructans had high degree of polymerization. This is due to a sample in the plaque is concentrated almost in its totality at the application point. Unlike inulin (I) which showed fructans of different polymerization degree, coinciding with those results pez, Mancilla-Margalli, and Mendoza-Diaz (2003) reported by Lo pez-Medina, and Lo pez (2009). Presence of and Mellado-Mojica, Lo fructans with low degree of polymerization is typical of oligofructose (O), mainly of the Fn series (without glucose units) (Kelly, 2008). Fig. 1B shows the carbohydrates profile of DAM. Spots corresponding to glucose, fructose and sucrose, typical of apple components appeared in all samples. Spots corresponding to commercial prebiotics were observed in all the samples. In the control matrix (CL) fructans spots do not appear. The thin layer chromatography has been used successfully for analysis of fructooligosaccharides even in complex biological samples (Reiffov a& Nemcov a, 2006). 3.1.2. High-performance anion-exchange chromatography pulsed amperometric detection (HPAEC-PAD) In Fig. 2A the characteristic peaks of inulin are shown, where the time of retention was from 14.5 to 60 min, are characterized by a higher proportion of the Gn serie (a glucose molecule), 1 K ¼ 1kestose, F3 ¼ inulotriose, 1N ¼ 1-nystose, F4 ¼ inulotetraose, DP5 ¼ 1-fructofuranosylnystose, and F5 ¼ Inulopentaose. Presence of inulin in extract of DAM supplemented with inulin is shown in Fig. 2B, where peaks and retention time were identified. Fig. 2C corresponds to DAM CL, where presence of fructans was not observed. This behavior was similar in all formulations (data not shown). 3.1.3. Enzymatic quantification of fructans (Kit MEGAZYME) The final fructans content in the DAM were level 1 ¼ 70.4, level 2 ¼ 110.02 and level 3 ¼ 150.4 g/kg of DAM. According to these results, an approximate portion of 35 g daily of DAM in any of the levels studied, would cover the recommendation of suggested daily intake of 2e5 g (Beneo Orafti) (Araújo, Carvalho, Leandro, Furtado, & Moraes, 2010; Roberfroid, 2005; VolpiniRapina, Ruriko, & Conti-Silva, 2012; ). Fructans concentration increased because of dehydration process applied on the
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Fig. 1. Thin-Layer chromatography of commercial prebiotics solutions (1A), and extracts of dehydrated apple matrices (1B). DP ¼ degree of polymerization, A ¼ agave fructans; I ¼ inulin, O ¼ oligofructose STD ¼ standards, G ¼ Glucose, F ¼ fructose, S ¼ sucrose, K ¼ 1-kestose, N ¼ 1-nystose and DP5 ¼ 1-fructofuranosylnystose); CL ¼ control matrix without prebiotics. Stationary phase: silica gel plates with aluminum support; mobile phase: propanol-agua-butanol (12 mL : 4 mL : 3 mL); detection reagent: anilineediphenylamineephosphoric acid in acetone; volume of sample 1 mL.
matrices. Volpini-Rapina et al. (2012) evaluated addition of inulin and oligofructose/inulin, on orange cake by the same method. Content of fructans were 90 and 83 g/kg respectively. The supplemented fructans were present in matrices and resisted processing conditions. Results in the present study are consistent with those reported by Huebner, Wehling, Parkhurst, and Hutkins (2008), who carried out a prebiotic activity essay following exposure commercial fructans in solution at different pH and temperatures conditions. They also discovered that significant changes occurred when low pH and temperatures above 85 C were combined. Conditions used in the process of DAM in
this study, were below this temperature. The effect of temperature and water activity has been only evaluated on fructans powder (Espinosa-Andrews & Urías-Silvas, 2012). 3.2. Moisture content, aw, and mechanical properties Physicochemical and mechanical properties of DAM are shown in Table 2, where it is observed that level 3 showed significant differences. Moisture content of DAM was not affected by relationship or type of fructans according to control DAM, as it was found within the range of moisture for this type of food. However,
Fig. 2. High-Performance Anion Exchange Chromatography-Pulsed Amperometric Detection. Chromatographics profiles of fructans of commercial inulin (2A), extract of dehydrated apple matrix with inulin (2B) and extract of dehydrated apple matrix without inulin (2C). DP ¼ degree of polymerization, F ¼ fructan serie without glucose molecule, K ¼ 1-kestose, F3 ¼ Inulotriose, N ¼ 1-nystose and DP5 ¼ 1-fructofuranosylnystose. Column: CarboPac-PA100 (4 250 mm); mobile phase: gradient of sodium acetate, in 0.15 mol/L NaOH; flow: 0.8 mL/min; volume of sample 25 mL.
lez-Herrera et al. / LWT - Food Science and Technology 65 (2016) 1059e1065 S.M. Gonza Table 2 Physicochemical and mechanical properties for each formulation of dehydrated apple matrix supplemented with prebiotics. Formulation
1 2 3 4 5 6 7 CL Pooled SD
Physicochemical properties
Mechanical properties
Moisture content (g/kg)
aw
Hardness N
Stickiness N
156.0a 163.0a 178.0a 188.0a 165.0a 160.0a 166.0a 169.0a
0.563c 0.540b 0.696e 0.670d 0.478a 0.544b 0.479a 0.506b
7.1d 4.0b 2.4a 5.0c 4.5bc 6.2d 6.7d 4.1bc
0.358ab 0.460bc 0.596bc 0.653de 0.872f 0.785ef 0.374ab 0.268a
15.6
0.004
1.11
0.093
Different letters within the columns indicate different means (p < 0.05, n ¼ 3). CL ¼ dehydrated apple matrix without prebiotics. SD ¼ Standard deviation.
significant differences between treatments and the control for aw were found. The highest value was observed in the formulation 3 that was supplemented only with agave fructans. The formulation 3 (A) presented the lowest hardness value, statistically different from the other studied prebiotics and control. These results can be related to the aw. The highest value corresponds to formulation 3 (A). This may be because of the technological properties of the agave fructans, which have a complex structure. They are different to the inulin-type fructans. It has been reported that their behavior is dependent on aw and temperature values when they have been studied without being applied in food (Espinosa-Andrews & Urías-Silvas, 2012). The highest hardness value correspondent to formulation 1 (I), is consistent with that reported for other types of food matrixes, in which inulin or mixed inulin/oligofructose was applied, such as ice cream, chocolate and cake (El-Nagar, Clowes, Tudorica, Kuri, & Brennan, 2002; Farzanmehr & Abbasi, 2009; Volpini-Rapina et al., 2012). Stickiness of all treatments was significantly higher compared to control (Table 2). Several authors have reported that the increase in the stickiness of different foods with the addition of fructans, which can be related to the formation of a viscous gel matrix because of the gelling properties along with the ability to bind water of fructans such as inulin (El-Nagar et al., 2002; Farzanmehr & Abbasi, 2009; Volpini-Rapina et al., 2012). Espinosa-Andrews and UríasSilvas (2012) found that at water activities around 0.6, agave fructans caked and change to a sticky material, perhaps this is the cause of the stickiness in the DAM, but further studies would be required to confirm this.
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Formulations 1 and 7 (I and IOA) presented the lowest values of stickiness, and it is associated with high values of hardness. The characteristics presented in the DAM of agave fructans were different and showed a technological potential for commercial development of a product apple leather type, supplemented with these fructans. 3.3. Sensory analysis Intensity of sensory attributes and overall acceptability is shown in Table 3. From the results it was observed that the panel did not perceived any significative difference in the attributes such as acidity, sweetness, and stickiness between formulations and the control. However, hardness intensity of formulation 3 (A) was statistically different from the other formulations and control, having the lowest value. Among the other formulations, there was no difference in the perception of panel regarding hardness. In terms of general acceptability of DAM, formulation 3 (A) was the best qualified, statistically different from formulation 1 (I) and control. Sensory evaluation results may be related to data obtained from measurements of the aw and hardness, where formulation 3 (A) was the most accepted. It presented the lower hardness and the higher water activity. This suggests that agave fructans, incorporated in the matrix leather type, gave mechanical, physicochemical, and sensory properties suitable for this type of product. The formulation 1 (I) had the highest hardness in both kinds of measurements, instrumental and sensory evaluation. This effect has been reported in different types of food matrices such as ice cream, cake and chocolate (El-Nagar et al., 2002; Farzanmehr & Abbasi, 2009; Volpini-Rapina et al., 2012). However, in other foods such as cheeses and cured meats, hardness decreases as addition of inulin increases (Menegas, Pimentel, Garcia, & Prudencio, 2013; Salvatore, Pes, Mazzarello, & Pirisi, 2014). These results indicate that interactions are food matrix-depended. 3.4. Mathematical model, equations and component effects The equations generated from sensory attributes and mechanical properties of different formulations are presented in Table 4. Only those equations where evaluated parameters had significant influence on matrix components are shown. Special linear (data not shown), quadratic (data not shown) and cubic models were evaluated; the best fit for all variables was for the special cubic model. Fig. 3 shows the contour graphs, illustrating the effect of mixtures of fructans on DAM mechanical and sensorial parameters. In Fig. 3A, formulation 7 (inulin-oligofructose-agave fructans) and
Table 3 Sensory characteristicsa and overall acceptabilityb for each formulation of dehydrated apple matrix supplemented with prebiotics. Formulation
Trained panel
Untrained panel
Sourness
Sweetness
Stickiness
Hardness
Overall acceptability
1 2 3 4 5 6 7 CL
3.2a 3.4a 3.5a 3.1a 3.8a 3.4a 3.1a 3.6a
4.3a 4.2a 4.2a 3.4a 3.4a 3.2a 3.8a 3.8a
3.1a 2.6a 2.8a 2.9a 2.9a 2.2a 3.2a 3.1a
4.5a 3.4abc 2.5c 3.7ab 4.1ab 3.8ab 4.3ab 3.7ab
3.9bc 5.1ab 5.7a 4.4abc 4.7abc 3.8bc 3.3c 4.2bc
Poleed SD
1.34
1.17
1.30
1.54
1.30
Different letters within the columns indicate different means (p < 0.05 n ¼ 3). SD ¼ Standard deviation. CL ¼ dehydrated apple matrix without prebiotics. a Scale 1 ¼ Nothing 7 ¼ Very intense. b 1 ¼ I did not like it 7 ¼ I like it very much.
lez-Herrera et al. / LWT - Food Science and Technology 65 (2016) 1059e1065 S.M. Gonza
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Table 4 Predicted equations for experimental data of dehydrated apple matrix formulations supplemented with prebiotics with significant influence.
Sensory parameter Acceptability Hardness Mechanical properties Stickiness Hardness
Equation
R2
Y ¼ 3.93*I þ 4.8*O þ 5.6*A þ 0.93*I*O 0.93*I*A 5.06*O*A 12.99*I*O*A Y ¼ 4.53*I þ 2.6*O þ 2.53*A 1.73*I*O þ 2.13*I*A þ 1.2*O*A þ 27.00*I*O*A
0.749 0.890
Y ¼ 0.370*I þ 0.435*O þ 0.66*A þ 0.942*I*O þ 0.982*I*A þ 0.814*O*A-10.190*I*O*A Y ¼ 7.10*I þ 4.07*O þ 2.52A 3.49*I*O 1.37*I*A þ 12.72*O*A þ 31.46*I*O*A
0.826 0.956
I ¼ Inulin, O ¼ Oligofructose, A ¼ Agave fructans (p < 0.05 n ¼ 3).
Fig. 3. Ternary contour plots of effects of supplementation of inulin, oligofructose an agave fructans on mechanical hardness (3A), mechanical stickiness (3B), sensory hardness (3C), and overall acceptability (3D) of the dehydrated apple matrix.
formulation 6 (oligofructose-agave fructans) interaction, had a significant influence on mechanical hardness, as seen in the high values of coefficients (Table 4), indicating a synergistic effect of these mixtures. The highest hardness value is located in the inulin vertex. This behavior matches the sensory properties in relation to formulation 7, which indicates that while the inulin ratio increases, hardness also increases. In the formulation 6, hardness was not perceived by the panel (Fig. 3C), but interaction inulin-agave fructans inversely affected general acceptability of the product (Fig. 3D), showing high values of coefficients in mixtures (Table 4) and an antagonistic effect, suggests a significant influence of this attribute. Stickiness is also manifested in inverse relationship to hardness, being lower in inulin-oligofructose- agave fructans mixture and the inulin vertex. The hardness values tend to be lower in the agave fructans-inulin and agave fructans-oligofructose mixtures as they approach the agave fructans and inulin vertices (Fig. 3A). As a result, it can be considered that interaction of these mixtures with high proportions of agave fructans or oligofructose have an antagonistic effect for this property as it is confirmed by the coefficients (Table 4), in such a way that these DAM have a softer texture, reflecting a higher acceptability value (Fig. 3D). In general, mixtures of fructans did not have a desirable impact on the acceptability of the matrices. Agave fructans and oligofructose
applied individually give matrices with desirable texture features. The results obtained from analysis of the model reveal that the optimal formulation based on acceptability for this product, is to use prebiotics individually. 4. Conclusions This study shows that the addition of mixtures of agave fructans, inulin and oligofructose changed the mechanical properties of hardness and stickiness of dehydrated apple matrix in relation to the control matrix, independently of the prebiotic type used in the mixture. The above findings reflected a decrease in consumer acceptability. Supplementation with only agave fructans to the matrix was very effective to improve the texture. Consumer acceptability was higher than those of the control matrix and the other evaluated formulations. From the above results, it has been demonstrated that the potential of agave fructans in these type of products extends the possibility to apply them in other processed food matrices. More studies are needed to verify the prebiotic potential. Acknowledgments Authors express their deep gratitude to M.C. Ma. de Jesus
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