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Organogels as novel ingredients for low saturated fat ice creams
Accepted Manuscript Organogels as novel ingredients for low saturated fat ice creams Maria Eletta Moriano, Cristina Alamprese PII:
S0023-6438(17)30513-3
DOI:
10.1016/j.lwt.2017.07.034
Reference:
YFSTL 6393
To appear in:
LWT - Food Science and Technology
Received Date: 21 April 2017 Revised Date:
17 July 2017
Accepted Date: 22 July 2017
Please cite this article as: Moriano, M.E., Alamprese, C., Organogels as novel ingredients for low saturated fat ice creams, LWT - Food Science and Technology (2017), doi: 10.1016/j.lwt.2017.07.034. 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.
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Organogels as novel ingredients for low saturated fat ice creams
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Maria Eletta Moriano, Cristina Alamprese*
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Department of Food, Environmental and Nutritional Sciences (DeFENS), Università
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degli Studi di Milano, via G. Celoria 2, 20133 Milan, Italy
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*Corresponding Author. E-mail: [email protected]; Phone: +39 0250319187;
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Fax: +39 50319190
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ACCEPTED MANUSCRIPT Abstract
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The aim of this work was to evaluate the use of sunflower oil organogels made with
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phytosterols and γ-oryzanol as milk cream substitutes in artisanal ice creams. Fat
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amount (4 and 8 g/100 g) and type (milk cream, sunflower oil, and organogels
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containing two levels of gelators) were considered as factors. The higher fat amount
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significantly decreased density (1.08±0.01 g/mL vs 1.10±0.01 g/mL) and soluble solid
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content (27.2±0.3 °Bx vs 30.1±0.3 °Bx) of mixes, as well as ice cream overrun
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(31.1±0.6% vs 37.3±0.6%) and melting rate (2.5±0.1 g/min vs 2.9±0.1 g/min). The use
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of organogels with the highest gelator concentration yielded ice creams with quality
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characteristics comparable to those of the samples containing milk cream, and even
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better overrun (42.4±0.8% vs 37.1±0.8%) and melting starting time (20±1 min vs 16±1
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min). Thus, the application of organogels in artisanal ice creams is a successful
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approach in order to obtain “low saturated fat” products (saturated fat < 0.9 g/100 g)
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“with added plant sterols and stanols” intended for people who want to lower their
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blood cholesterol level.
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Keywords: oleogel; milk cream; sunflower oil; fat amount; phytosterols.
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Abbreviation list: ANOVA, analysis of variance; At/A0, ratio between ice cream sample
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area at different times of melting referred to the area at the initial time; K, consistency
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coefficient; LSD, Least Significant Difference test; MC, milk cream; MC4, ice cream
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sample made with 4 g/100 g milk cream; MC8, ice cream sample made with 8 g/100 g
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milk cream; MSNF, milk solids not fat; n, flow behaviour index; OG, organogel;
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OG_12, organogel with 12 g/100 g gelators; OG_8, organogel with 8 g/100 g gelators;
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ACCEPTED MANUSCRIPT OG4_12, ice cream sample made with 4 g/100g organogel containing 12 g/100 g
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gelators; OG4_8, ice cream sample made with 4 g/100 g organogel containing 8 g/100 g
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gelators; OG8_12, ice cream sample made with 8 g/100 g organogel containing 12
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g/100 g gelators; OG8_8, ice cream sample made with 8 g/100 g organogel containing 8
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g/100 g gelators; Rt/R0, ratio between ice cream sample height and width at different
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times of melting referred to the ratio at the initial time; SO, sunflower oil; SO4, ice
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cream sample made with 4 g/100 g sunflower oil; SO8, ice cream sample made with 8
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g/100 g sunflower oil.
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ACCEPTED MANUSCRIPT 1. Introduction
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High amounts of trans and saturated fatty acids in the diet represent a major concern
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since these compounds are known to be atherogenic, contributing to the build-up of
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cholesterol and other substances in artery walls (Marangoni & Garti, 2011). A
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consumption of saturated fat lower than 10% of the daily energy is recommended by
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dietary guidelines of governing bodies worldwide, while an increasing consumption of
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mono and polyunsaturated fatty acids from vegetable (and vegetable oil) sources is
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suggested (EFSA, 2017; Stortz, Zetzl, Barbut, Cattaruzza, & Marangoni, 2012; WHO,
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2015).
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Unfortunately, the mouthfeel and textural properties of many foods including ice cream,
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chocolate, and meat products are due to saturated fats, thus, their replacement with
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unsaturated oils is a considerable technical challenge (Stortz et al., 2012). In particular,
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the physical properties of fat play a significant role in ice cream mix behaviour during
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freezing and in formation of the final structure. The two factors of interest are the
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proportion of liquid fat present in the fatty phase at the time of entry into the freezer and
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the way in which the fat crystallizes (Berger, 1990), both affected by the proportion of
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saturated fatty acids.
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A novel strategy to reduce the amount of saturated fats in food products relies in the
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ability to structure liquid oil and make it behave like a solid crystalline fat, without
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causing significant changes in the chemical composition. A major approach is to
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incorporate specific components (named “gelators”) that, by various mechanisms, are
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able to alter the oil physical properties so that the rheological behaviour resembles that
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of fats. These novel oil-based materials are usually called “organogels” or “oleogels”,
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being gels where the liquid phase is oil and not water as in a hydrogel (Marangoni &
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is based on the use of a plant sterol (i.e., β-sitosterol) and a plant sterol ester (i.e., γ-
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oryzanol) as gelators. The building blocks of this gel are self-assembled tubules and the
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onset of assembly is strongly dependent on gelator concentration. The kinetic of the
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aggregation depends considerably on the details of the system, such as the sitosterol-
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oryzanol ratio, the type of sterol, the cooling temperature, the quiescent or stirring
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conditions, etc. At least 2-4 g/100 g total sterols are needed to form a gel at 5 °C. The
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optimal composition of the gelator mixture in terms of maximal organogel firmness is a
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1:1 molar ratio of sitosterol and oryzanol, that is a 40:60 weight ratio. With increasing
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temperatures, the progressive dissolution of sitosterol and oryzanol tubules leads to the
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gel melting (Bot & Flöter, 2011).
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Apart from the good structuring properties, phytosterol-based organogels are
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particularly interesting because phytosterol intake by foods is associated with a
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significant LDL-cholesterol lowering. For the recommended intake of 2 g/day, a 9%
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lowering of LDL-cholesterol is expected (Demonty et al., 2009).
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Notwithstanding the high interest in food-grade organogels meant by the packed
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literature in this field, few papers deal with oleogel applications in real food systems
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(Aguirre-Mandujano, Lobato-Calleros, Garcia, & Vernon-Carter, 2009; Calligaris,
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Manzocco, Valoppi, & Nicoli 2013; Goldstein & Seetharaman, 2011; Manzocco,
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Anese, Calligaris, Quarta, & Nicoli, 2012; Stortz et al., 2012). Only Zulim-Botega,
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Marangoni, Smith, and Goff (2013a,b) studied the application of oleogels in ice cream.
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In particular, performances of rice bran wax, candelilla wax, or carnauba wax oleogels
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in ice creams formulated with 10 or 15 g/100 g fat were evaluated. They demonstrated
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ACCEPTED MANUSCRIPT the potentials of rice bran wax oleogels to develop fat structure in ice cream with high
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fat concentration (15 g/100 g), in the presence of glycerol monooleate as emulsifier.
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The aim of this work was to study the possibility of producing healthier artisanal ice
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creams by substituting milk cream with phytosterol organogel systems based on
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sunflower oil. In particular, a cold-pressed sunflower oil was used, in order to reduce
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the amount of saturated fatty acids brought in the final product and to enrich the ice
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cream in antioxidant compounds (i.e., α- and β-tocopherol). Quality features of ice
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creams were studied as a function of the amount (4 and 8 g/100 g) and type of fat used
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(milk cream, sunflower oil, and organogels containing two different levels of gelators),
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2. Materials and methods
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2.1 Organogel preparation
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In organogel (OG) preparation the following ingredients were used: cold-pressed
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sunflower oil kindly supplied by Il frutteto Incantato di Montefiore (Recanati, Italy), γ-
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orizanol (Sochim International, Cornaredo, Italy), and phytosterol complex concentrate
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95% (Sochim International). The cold-pressed sunflower oil had a saturated fatty acid
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level of 10.2%, and a α- and β-tocopherol content of 540 mg/kg and 25 mg/kg,
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respectively. The phytosterol concentrate contained β-sitosterol (51.62 g/100 g),
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campesterol (21.85 g/100 g), stigmasterol (21.23 g/100 g), brassicasterol (1.13 g/100 g),
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β-sitostanol (0.81 g/100 g), campestanol (0.49 g/100 g), and other sterols and stanols
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(2.87 g/100 g).
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ACCEPTED MANUSCRIPT Two levels of gelators were considered in OG production: 8 g/100 g (OG_8) or 12
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g/100 g (OG_12) on oil basis. Gelators consisted of a phytosterol concentrate and γ-
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orizanol mixture in 40:60 weight ratio.
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Sunflower oil was warmed up to 70 °C in a thermostatic bath; then the given amount of
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gelators was added under continuous stirring. The stirring phase lasted for 35 min, until
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the total dissolution of gelators in the oil. Then, the hot mixture of oil and gelators was
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added to ice cream mix during pasteurization as described in §2.3. Since the application
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of a heating-cooling temperature cycle causes the gelator tubules to dissolve and reform
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(Bot, den Adel, Regkos, Sawalha, Venema, & Flöter, 2011), the cooling phase
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necessary to the formation of the OG was not carried out because the addition of the
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lipid phase to the ice cream mix during heating would have dissolved the gel in any
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case. The typical tubules of this kind of OG were supposed to form during cooling of
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the ice cream mix, as already demonstrated for oil in water (o/w) emulsions: the initial
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creation of the emulsion can be done more or less independently from a later formation
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of the OG network in the lipid phase (Duffy, Blonk, Beindorff, Cazade, Bot, &
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Duchateau, 2009).
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2.2. Ice cream formulations
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Experimental ice creams were formulated as reported in Table 1, varying the amount of
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fat (4 or 8 g/100 g) and keeping constant the quantity of added sugars (14.9 g/100 g)
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and total solids (30.6 ± 0.3 g/100 g). Fresh pasteurized skim milk (Centrale del Latte di
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Milano, Milan, Italy) and pasteurized milk cream (Centrale del Latte di Milano, Milan,
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Italy) were purchased from a local supermarket, while all the powder ingredients were
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ACCEPTED MANUSCRIPT kindly supplied by Comprital S.p.A. (Settala, Italy). Pasteurized milk cream contained
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35.0 g/100 mL fat, 68% of which were saturated fatty acids.
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Experimental samples were identified by a code consisting of two letters and two
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numbers: the letters refer to the type of fat used (MC, milk cream; OG, organogel; SO,
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sunflower oil), the first number to the amount of fat in the formulation (4 or 8 g/100 g),
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and the second number to the percentage of gelators used for oil structuring (8 or 12
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g/100 g on oil basis).
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2.3. Ice cream production
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Ice cream mixes were prepared as reported by Rossi, Alamprese, Casiraghi, and Pompei
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(1999), by using a Pastomaster 60 Tronic and a Labotronic 20-30 batch freezer
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(Carpigiani S.r.l, Anzola Emilia, Italy). Briefly, liquid ingredients were heated up to 50
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°C before the addition of solid ingredients. SO and OG, when present, were added to
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milk during heating just before the solid ingredient addition. The mix (15 kg) was then
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pasteurised at 85 °C for about 1 min and aged at 4 °C for 24 h. Mix freezing was carried
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out in 3 L batches, measuring ice cream extrusion time using a chronometer.
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Immediately after extrusion, ice cream temperature was evaluated by a thermometer
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inserted in the centre of the product. After packaging, ice cream samples were stored for
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24 h at -30 °C and then conditioned for 24 h at -16 °C before analyses. Two
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technological replicates were carried out for each formulation.
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2.3. Ice cream mix analyses
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Ice creams mixes were characterized in terms of viscosity, density and soluble solids as
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reported by Moriano and Alamprese (2017). In particular, viscosity was evaluated in
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ACCEPTED MANUSCRIPT duplicate at 4 °C by means of flow curves performed by a Physica MCR 300 rheometer
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(Anton Paar, Graz, Austria) equipped with a cone-plate geometry (CP50-1), ranging
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shear rate from 20 to 500 s-1. Results are expressed as the average of two technological
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replicates in terms of apparent viscosity (mPa s) at 290 s-1. This value of shear rate was
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chosen because it represents an average pipe wall shear rate during fluid food pumping
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(Alamprese, Pompei, & Guatelli, 2001). Moreover, consistency coefficient (K; mPa sn)
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and flow behaviour index (n; dimensionless) were calculated by fitting flow curves with
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the power law equation (Steffe, 1996).
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2.4. Ice cream analyses
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Analyses of ice cream quality characteristics were carried out as reported in Alamprese,
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Foschino, Rossi, Pompei, and Savani (2002), and in Moriano and Alamprese (2017).
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Overrun is reported as the percentage of mix volume increase during freezing, measured
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on ten 230 mL samples for each production. Firmness was determined by an Instron
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Universal Testing Machine (Mod. 4301, Instron Ltd., High Wycombe, UK) performing
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penetration tests on 50 mL samples. A stainless steel cylindrical probe (8 mm diameter)
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connected to a 100 N load cell was used, penetrating ice cream samples for 18 mm,
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using a crosshead speed of 50 mm/min. Results, expressed as the maximum load (N)
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opposed by ice cream to a 15 mm penetration, are the average of at least ten
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measurements for each production. Melting behaviour, reported as melting starting time
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and melting rate, was evaluated at 20 °C on 230 mL ice cream samples, recording the
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weight of melted ice cream (g) as a function of time (up to 90 min). Results are the
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average of three replicates for each production. During melting tests, pictures of the
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samples were taken every 15 min and elaborated by a purposely developed image
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ACCEPTED MANUSCRIPT analysis method (Image Pro Plus 7.0; Media Cybernetics Inc., Rockville, MD, USA).
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The following shape retention indexes were calculated: Rt/R0, ratio between sample
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height and width at different times (0, 15, 30, 45, 60, 75, 90 min) referred to the ratio at
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the initial time (0 min); At/A0, ratio between the area at each time referred to the area at
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the initial time. Ice cream colour was measured using a reflectance colorimeter Chroma
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Meter CR 210 (Minolta Camera Co. Ltd, Tokio, Japan), with standard illuminant C.
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CIE L*a*b* indexes are reported as the average of nine determinations, carried out on
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three 230 mL samples of each production.
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2.5. Statistical analysis
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Two-way analysis of variance (ANOVA) was applied to the analytical data in order to
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study the effects of the two considered factors: amount of fat (4 g/100 g and 8 g/100 g)
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and type of fat (MC, SO, OG_8, and OG_12). The interaction term (fat amount × fat
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type) was also considered in ANOVA; it has not been reported in result tables, but
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commented in the text only when significant (p < 0.05). The Least Significant
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Difference (LSD) test at p < 0.05 was used to evaluate significant differences among the
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averages (Statgraphics Plus 5.1, Statistical Graphics Corp., Herndon, VA, USA).
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3. Results and discussion
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3.1. Ice cream mix properties
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Results of ice cream mix characteristics and LSD test after two-way ANOVA are shown
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in Table 2. Formulations with higher amount of fat showed significantly (p < 0.05)
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decreased mix density and soluble solid content, due to the lower density of fat with
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respect to the serum phase and the lower level of milk solids not fat (MSNF; Table 1).
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the exception of OG_12 that led to a significantly (p < 0.05) higher Brix degree value,
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probably ascribable to gelators.
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Rheological behaviour of ice cream mixes was mainly affected by fat type rather than
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amount. In particular, the use of SO or OG_8 significantly (p < 0.05) decreased the
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apparent viscosity and the consistency coefficient of the mixes with respect to samples
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containing MC or OG_12. This result is related to the higher amount of saturated fatty
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acids in MC, yielding higher proportions of crystallized fat at 4 °C with respect to those
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of samples containing SO or OG_8. OG_12 showed a higher structuring effect with
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respect to OG_8, resulting in an apparent viscosity of ice cream mixes not significantly
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(p > 0.05) different from that of samples made with MC. This result revealed that an
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OG network was actually created in the ice cream mix containing OG_12, increasing
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the apparent viscosity of the system. The higher amount of gelators needed to structure
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sunflower oil in the ice cream emulsion is in agreement with previous findings by
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Sawalha, den Adel, Venema, Bot, Flöter, and van der Linden (2012), who reported that
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in the emulsion, the water molecules bind to the β-sitosterol molecules, forming
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monohydrate crystals that hinder the formation of the tubules thus resulting in a weaker
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emulsion-gel.
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Sunflower oil is a Newtonian fluid, thus its flow behaviour index (n) is equal to 1.
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Rheology of sunflower oil affected the rheological behaviour of ice cream mixes
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containing this type of fat (structured or not). Indeed, ice cream mixes SO, OG_8, and
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OG_12 showed significantly (p < 0.05) higher values of n with respect to samples
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produced with MC. As it is shown in Fig. 1, the behaviour of mixes containing OG with
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12 g/100 g gelators (OG4_12 and OG8_12) was more similar to those produced with
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MC rather than to samples made with SO or OG_8, in agreement with the higher
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structuring ability of the higher gelator concentration.
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3.2. Quality characteristics of ice creams
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No significant (p > 0.05) differences were measured in extrusion time and temperature
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of ice cream samples as a function of fat amount or type. All ice cream mixes were
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extruded in 7.8 ± 0.2 min, reaching a temperature of -7.9 ± 0.4 °C. On the contrary, both
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the considered factors significantly (p < 0.05) affected quality characteristics of ice
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creams in terms of overrun and melting behavior (Table 3). As already observed in
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previous works (Alamprese et al., 2002; Roland, Philips, & Boor, 1999; Zulim-Botega
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et al., 2013b), a higher amount of fat accounted for a lower overrun and melting rate.
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This can be related to the corresponding lower level of MSNF in the ice creams (Table
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1), bringing in the product less proteins and consequently modifying whipping
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properties of mix and melting behavior of the final product (Goff, 1997). As regards the
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type of fat, SO and OG_8 worsened the ice cream overrun with respect to MC, while
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the use of OG_12 resulted in an overrun even higher than that of the ice cream
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containing MC. Moreover, in comparison with MC samples, ice creams made with
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OG_12 showed a significantly (p < 0.05) higher melting starting time and a similar
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melting rate. Thus, it can be concluded that the use of OG_12 accounted for an
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improvement in ice cream quality characteristics with respect to the use of non-
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structured SO. This can be related to the higher ratio of solid:liquid fat attained during
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mix ageing, since, as reported by Goff (1997), a partially crystalline emulsion is needed
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for partial fat coalescence in the whipping and freezing steps, leading to air bubble
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stabilization and, as a consequence, to higher overrun and melting resistance. Similar
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a rice bran wax oleogel instead of high oleic sunflower oil improves overrun and
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melting rate of ice cream.
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The fat amount effect on ice cream firmness was not in agreement with previous papers
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reporting a higher softness with the increasing of fat content (Alamprese et al., 2002;
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Roland et al., 1999). However, it has to be highlighted that the formulation balancing is
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very important to this aspect. In this work, mix total solids have been kept constant,
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meaning that in recipes with a low amount of fat there was a higher content of MSNF
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(Table 1) including also lactose and minerals. According to the Raoult’s law, a higher
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molar fraction of low molecular weight solutes accounts for a higher freezing point
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depression effect (LeBail & Goff, 2008). This means that at a given temperature ice
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creams with higher MSNF concentration (corresponding in this research to the samples
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with lower amount of fat) will have a higher amount of unfrozen water, thus justifying
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the lower ice cream firmness.
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The interaction term fat amount × type was also significant (p < 0.05). Actually, looking
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at each fat type separately (Table 4), the increase in fat amount always yielded firmer
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ice creams, with the exception of the samples containing SO. In this case, it is likely that
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the lower amount of solid fat at the temperature of analysis (-16 °C) caused the lower
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ice cream firmness.
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All the ice cream samples showed a good shape retention during melting (Fig. 2).
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However, the significantly (p < 0.05) highest Rt/R0 values were obtained with the use of
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OG_12, confirming the good performance of this type of fat in comparison with SO and
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even MC, the latter resulting in ice creams with significantly (p < 0.05) lower Rt/R0
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values (Figs. 3A and 3B). The higher fat amount accounted for significantly (p < 0.05)
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these samples (Table 3).
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Color of ice cream samples was measured in order to highlight possible effects of the
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different fat types and amounts used. In all samples, L* values ranged from 93.0 to
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95.3, a* from -3.9 to -2.9, and b* from 5.3 to 6.4. No significant (p > 0.05) differences
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were observed. Thus it can be concluded that the different color of MC with respect to
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SO and OG did not modify visual appearance of ice creams.
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4. Conclusions
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In conclusion, the application of organogels in artisanal ice creams as milk cream
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substitutes is a successful approach in order to obtain healthier products. In particular,
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ice creams produced with OG containing 12 g/100 g gelators showed similar or even
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better quality characteristics with respect to samples made with MC.
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Ice creams produced with 4 or 8 g/100 g OG contained 0.48 g/100 g and 0.86 g/100 g
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saturated fats, respectively, representing about 3 and 5% of the total energy content of
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the products. Thus, in agreement with Regulation (EC) No 1924/2006, they can be
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claimed as “low saturated fat” ice creams. Actually, the Regulation states that the claim
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can be used if the sum of saturated fatty acids and trans-fatty acids in the product does
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not exceed 1.5 g/100 g for solids and does not provide more than 10% of energy. In MC
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samples, saturated fatty acids ranged from 2.74 to 5.47 g/100 g as a function of the fat
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amount.
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Moreover, because of the presence of phytosterols and phytostanols, the label of ice
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creams containing OG shall contain the words “with added plant sterols and plant
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stanols”, the amount of phytosterols and phytostanols used as ingredients, and a
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cholesterol level (Commission Regulation (EC) No 608/2004). Considering an average
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ice cream serving portion of 150 g, the developed products does not exceed the limit
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about the consumption of no more than 3 g/day of added plant sterols/stanols stated by
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the European legislation.
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Acknowledgements
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This work was supported by the Italian Association of Food Product Industries (AIIPA)
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- “Artisanal Ice Cream Ingredients” Group.
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oleogels (pp. 49–79). Urbana: AOCS Press. Bot, A., den Adel, R., Regkos, C., Sawalha, H., Venema, P., & Flöter, E. (2011). Structuring in β-sitosterol+γ-oryzanol-based emulsion gels during various stages of
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Calligaris, S., Manzocco, L., Valoppi, F., & Nicoli M.C. (2013). Effect of palm oil
replacement with monoglyceride organogel and hydrogel on sweet bread properties.
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phytostanols and/or phytostanol esters. Official Journal of the European Union,
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L97, 44–45.
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Demonty, I., Ras, R.T., van der Knaap H.C.M., Duchateau, G.S.M.J.E., Meijer, L., Zock, P.L., … & Trautwein, E.A. (2009). Continuous dose-response relationship
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of the LDL-cholesterol–lowering effect of phytosterol intake. The Journal of
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Nutrition, 139, 271–284.
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and impact on in vitro digestion. Journal of the American Oil Chemists’ Society,
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EFSA (2017). Overview on dietary reference values for the EU population as derived by the EFSA panel on dietetic products, nutrition and allergies (NDA).
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Goff, H.D. (1997). Colloidal aspects of ice cream - A review. International Dairy
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Journal, 7, 363–373. Goldstein, A., & Seetharaman, K. (2011). Effect of monoglyceride stabilized oil in water emulsion shortening on cookie properties. Food Research International, 44,
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1476–1481.
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LeBail, A., & Goff, H.D. (2008). Freezing of bakery and dessert products. In J.A. Evans (Ed.), Frozen food science and technology (pp.184-204). Oxford: Blackwell
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Publishing Ltd.
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Manzocco, L., Anese, M., Calligaris, S., Quarta, B., & Nicoli, M.C. (2012). Use of monoglyceride hydrogel for the production of low fat short dough pastry. Food
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Chemistry, 132, 175–180.
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Marangoni, A., & Garti, N. (2011). An overview of the past, present, and future of
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organogels. In A.G. Marangoni & N. Garti (Eds.), Edible oleogels (pp. 1–17).
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Urbana: AOCS Press.
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Moriano, M.E., & Alamprese C. (2017). Honey, trehalose and erythritol as sucrosealternative sweeteners for artisanal ice cream. A pilot study. LWT - Food Science
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& Technology, 75, 329–334.
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the European Union, L12, 3–18.
Roland, A.M., Philips, L.G., & Boor, K.J. (1999). Effects of fat content on the sensory properties, melting, color, and hardness of ice cream. Journal of Dairy Science, 82, 32–38. Rossi, M., Casiraghi, E., Alamprese, C., & Pompei, C. (1999). Formulation of lactose reduced ice cream mix. Italian Journal of Food Science, 11, 3–18.
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Organogel-emulsions with mixtures of β-sitosterol and γ-oryzanol: influence of
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water activity and type of oil phase on gelling capability. Journal of Agricultural
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and Food Chemistry, 60, 3462-3470.
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Steffe, J.F. (1996). Introduction to rheology. In Rheological methods in food process engineering (2nd ed., pp. 1-93). East Lansing: Freeman Press.
Stortz, T.A., Zetzl, A.K., Barbut, S., Cattaruzza, A., & Marangoni A.G. (2012). Edible
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oleogels in food products to help maximize health benefits and improve nutritional
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profiles. Lipid Technology, 24(7), 151–154.
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WHO (2015). Healthy diet. Fact sheet No. 394. Updated September 2015. http://www.who.int/mediacentre/factsheets/fs394/en/, accessed on 10/07/2017. Zulim-Botega, D.C., Marangoni, A.G., Smith, A.K., & Goff H.D. (2013a). The potential application of rice bran wax oleogel to replace solid fat and enhance
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unsaturated fat content in ice cream. Journal of Food Science, 78, C1334-C1339.
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Zulim-Botega, D.C., Marangoni, A.G., Smith, A.K., & Goff H.D. (2013b). Development of formulations and processes to incorporate wax oleogels in ice
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cream. Journal of Food Science, 78, C1845-C1851.
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Figure 1. Flow curves (mean of two technological replicates) of ice cream mixes
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produced with milk cream (MC; ◊), sunflower oil (SO; □), organogel with 8 g/100 g
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gelators (OG_8; ∆) and organogel with 12 g/100 g gelators (OG_12; ○), containing 4
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g/100 g fat (A) and 8 g/100 g of fat (B). Standard deviation values ranged from 0.9 to
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6.8 mPa s.
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Figure 2. Examples of pictures taken during melting test of ice creams containing 4
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g/100 g fat, produced with milk cream (MC4), sunflower oil (SO4), organogel with 8
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g/100 g gelators (OG4_8), and organogel with 12 g/100 g gelators (OG4_12). The
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Figure 3: Shape retention indexes (Rt/R0 and At/A0) as a function of melting time of ice
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creams produced with milk cream (MC; ◊), sunflower oil (SO; □), organogel with 8
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g/100 g gelators (OG_8; ∆) and organogel with 12 g/100 g gelators (OG_12; ○),
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containing 4 g/100 g fat (A, C) and 8 g/100 g of fat (B, D). Error bars represent standard
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deviation values of two technological replicates. Rt/R0, ratio between ice cream sample
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height and width at different times of melting referred to the ratio at the initial time;
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At/A0, ratio between ice cream sample area at different times of melting referred to the
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area at the initial time.
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Table 1. Formulation and composition of ice cream samples produced in order to study the effect of fat amount and type MC8
SO4
SO8
OG8_8
OG4_12
OG8_12
75.2 3.9 5.4 12.0 2.9 0.2 0.4
75.2 7.9 1.4 12.0 2.9 0.2 0.4
75.2 3.9 5.4 12.0 2.9 0.2 0.4
75.2 7.9 1.4 12.0 2.9 0.2 0.4
4.0 0.5 14.9 11.2 30.3
8.0 0.9 14.9 7.7 30.8
4.0 0.5 14.9 11.2 30.3
8.0 0.9 14.9 7.7 30.8
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Ingredients (g/100 g) Fresh skim milk 67.9 60.3 75.2 75.2 Fresh milk cream 11.2 22.8 Sunflower oil 3.9 7.9 Organogel 8 g/100 g gelators Organogel 12 g/100 g gelators Skim milk powder 5.4 1.4 5.4 1.4 Sucrose 12.0 12.0 12.0 12.0 Dextrose 2.9 2.9 2.9 2.9 Whey proteins 0.2 0.2 0.2 0.2 Stabilizers & Emulsifiers 0.4 0.4 0.4 0.4 Composition (g/100 g) Fat 4.0 8.0 4.0 8.0 of which saturated 2.7 5.5 0.5 0.9 Added sugars 14.9 14.9 14.9 14.9 MSNF 11.2 7.8 11.2 7.7 Total solids 30.4 31.0 30.3 30.8 MSNF, milk solids not fat; MC, milk cream; SO, sunflower oil; OG, organogel.
OG4_8
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ACCEPTED MANUSCRIPT Table 2. Results of ice cream mix properties (mean ± standard error values of two technological replicates) as a function of the two experimental factors studied: fat amount and type.
Density (g/mL)
Soluble solids (°Bx)
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K (mPa sn)
n (-)
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Fat amount (g/100 g) 4 30.1±0.3b 29.9±0.5a 78±3a 0.831±0.005a 1.10±0.01b a a a a 8 1.08±0.01 27.2±0.3 29.5±0.5 74±3 0.848±0.004b Fat type MC 1.08±0.01a 28.5±0.4a 32.2±0.7b 102±4c 0.799±0.006a SO 1.09±0.01a 28.0±0.4a 27.6±0.7a 66±4a 0.848±0.007b a a a a OG_8 28.0±0.4 27.1±0.7 60±4 0.862±0.007b 1.09±0.01 OG_12 1.09±0.01a 30.2±0.4b 31.9±0.7b 76±3b 0.850±0.005b MC, milk cream; SO, sunflower oil; OG_8, sunflower oil-based organogel with 8 g/100 g gelators; OG_12, sunflower oil-based organogel with 12 g/100 g gelators; K, consistency index; n, flow behavior index. a-c within the same factor, results with different superscript letters in the same column are significantly different (p < 0.05) on the basis of two-way ANOVA followed by the Least Significant Difference test.
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Overrun (%)
Firmness (N)
Melting behaviour
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Fat amount (g/100g) 4 37.3±0.6b 12.7±0.7a 18±1a 2.9±0.1b 8 15.4±0.7b 19±1a 2.5±0.1a 31.1±0.6a Fat type MC 37.1±0.8b 14±1a 16±1a 2.28±0.09a a a b SO 27.5±0.8 13±1 20±1 2.83±0.09b OG_8 29.9±0.8a 14±1a 18±1ab 2.98±0.09b OG_12 42.4±0.8c 15±1a 20±1b 2.67±0.09ab MC, milk cream; SO, sunflower oil; OG_8, sunflower oil-based organogel with 8 g/100 g gelators; OG_12, sunflower oil-based organogel with 12 g/100 g gelators; ts, starting time. a-b within the same factor, results with different superscript letters in the same column are significantly different (p < 0.05) on the basis of two-way ANOVA followed by the Least Significant Difference test.
ACCEPTED MANUSCRIPT Table 4. Firmness (mean ± standard error values of two technological replicates) of ice cream samples produced with different fat amount and type. Fat amount Type of fat Firmness (g/100 g) (N) MC4 4 MC 13±1 MC8 8 MC 15±1 SO4 4 SO 14±2 SO8 8 SO 11±2 OG4_8 4 OG_8 12±1 OG8_8 8 OG_8 16±1 OG4_12 4 OG_12 11±1 OG8_12 8 OG_12 18±1 MC, milk cream; SO, sunflower oil; OG_8, sunflower oil-based organogel with 8 g/100 g gelators; OG_12, sunflower oil-based organogel with 12 g/100 g gelators. See Table 1 for ice cream sample formulations.
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Highlights Organogels and milk cream led to ice cream mix with similar density and viscosity.
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Organogels produced ice cream with better overrun and melting starting time.
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Fat amount affected sample density, soluble solids, overrun and melting rate.
S0023-6438(17)30513-3
DOI:
10.1016/j.lwt.2017.07.034
Reference:
YFSTL 6393
To appear in:
LWT - Food Science and Technology
Received Date: 21 April 2017 Revised Date:
17 July 2017
Accepted Date: 22 July 2017
Please cite this article as: Moriano, M.E., Alamprese, C., Organogels as novel ingredients for low saturated fat ice creams, LWT - Food Science and Technology (2017), doi: 10.1016/j.lwt.2017.07.034. 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.
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Organogels as novel ingredients for low saturated fat ice creams
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Maria Eletta Moriano, Cristina Alamprese*
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Department of Food, Environmental and Nutritional Sciences (DeFENS), Università
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degli Studi di Milano, via G. Celoria 2, 20133 Milan, Italy
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*Corresponding Author. E-mail: [email protected]; Phone: +39 0250319187;
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Fax: +39 50319190
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ACCEPTED MANUSCRIPT Abstract
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The aim of this work was to evaluate the use of sunflower oil organogels made with
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phytosterols and γ-oryzanol as milk cream substitutes in artisanal ice creams. Fat
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amount (4 and 8 g/100 g) and type (milk cream, sunflower oil, and organogels
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containing two levels of gelators) were considered as factors. The higher fat amount
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significantly decreased density (1.08±0.01 g/mL vs 1.10±0.01 g/mL) and soluble solid
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content (27.2±0.3 °Bx vs 30.1±0.3 °Bx) of mixes, as well as ice cream overrun
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(31.1±0.6% vs 37.3±0.6%) and melting rate (2.5±0.1 g/min vs 2.9±0.1 g/min). The use
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of organogels with the highest gelator concentration yielded ice creams with quality
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characteristics comparable to those of the samples containing milk cream, and even
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better overrun (42.4±0.8% vs 37.1±0.8%) and melting starting time (20±1 min vs 16±1
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min). Thus, the application of organogels in artisanal ice creams is a successful
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approach in order to obtain “low saturated fat” products (saturated fat < 0.9 g/100 g)
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“with added plant sterols and stanols” intended for people who want to lower their
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blood cholesterol level.
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Keywords: oleogel; milk cream; sunflower oil; fat amount; phytosterols.
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Abbreviation list: ANOVA, analysis of variance; At/A0, ratio between ice cream sample
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area at different times of melting referred to the area at the initial time; K, consistency
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coefficient; LSD, Least Significant Difference test; MC, milk cream; MC4, ice cream
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sample made with 4 g/100 g milk cream; MC8, ice cream sample made with 8 g/100 g
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milk cream; MSNF, milk solids not fat; n, flow behaviour index; OG, organogel;
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OG_12, organogel with 12 g/100 g gelators; OG_8, organogel with 8 g/100 g gelators;
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ACCEPTED MANUSCRIPT OG4_12, ice cream sample made with 4 g/100g organogel containing 12 g/100 g
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gelators; OG4_8, ice cream sample made with 4 g/100 g organogel containing 8 g/100 g
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gelators; OG8_12, ice cream sample made with 8 g/100 g organogel containing 12
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g/100 g gelators; OG8_8, ice cream sample made with 8 g/100 g organogel containing 8
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g/100 g gelators; Rt/R0, ratio between ice cream sample height and width at different
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times of melting referred to the ratio at the initial time; SO, sunflower oil; SO4, ice
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cream sample made with 4 g/100 g sunflower oil; SO8, ice cream sample made with 8
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g/100 g sunflower oil.
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ACCEPTED MANUSCRIPT 1. Introduction
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High amounts of trans and saturated fatty acids in the diet represent a major concern
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since these compounds are known to be atherogenic, contributing to the build-up of
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cholesterol and other substances in artery walls (Marangoni & Garti, 2011). A
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consumption of saturated fat lower than 10% of the daily energy is recommended by
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dietary guidelines of governing bodies worldwide, while an increasing consumption of
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mono and polyunsaturated fatty acids from vegetable (and vegetable oil) sources is
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suggested (EFSA, 2017; Stortz, Zetzl, Barbut, Cattaruzza, & Marangoni, 2012; WHO,
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2015).
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Unfortunately, the mouthfeel and textural properties of many foods including ice cream,
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chocolate, and meat products are due to saturated fats, thus, their replacement with
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unsaturated oils is a considerable technical challenge (Stortz et al., 2012). In particular,
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the physical properties of fat play a significant role in ice cream mix behaviour during
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freezing and in formation of the final structure. The two factors of interest are the
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proportion of liquid fat present in the fatty phase at the time of entry into the freezer and
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the way in which the fat crystallizes (Berger, 1990), both affected by the proportion of
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saturated fatty acids.
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A novel strategy to reduce the amount of saturated fats in food products relies in the
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ability to structure liquid oil and make it behave like a solid crystalline fat, without
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causing significant changes in the chemical composition. A major approach is to
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incorporate specific components (named “gelators”) that, by various mechanisms, are
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able to alter the oil physical properties so that the rheological behaviour resembles that
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of fats. These novel oil-based materials are usually called “organogels” or “oleogels”,
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being gels where the liquid phase is oil and not water as in a hydrogel (Marangoni &
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ACCEPTED MANUSCRIPT Garti, 2011). One of the most interesting organogelling strategies for food applications
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is based on the use of a plant sterol (i.e., β-sitosterol) and a plant sterol ester (i.e., γ-
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oryzanol) as gelators. The building blocks of this gel are self-assembled tubules and the
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onset of assembly is strongly dependent on gelator concentration. The kinetic of the
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aggregation depends considerably on the details of the system, such as the sitosterol-
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oryzanol ratio, the type of sterol, the cooling temperature, the quiescent or stirring
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conditions, etc. At least 2-4 g/100 g total sterols are needed to form a gel at 5 °C. The
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optimal composition of the gelator mixture in terms of maximal organogel firmness is a
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1:1 molar ratio of sitosterol and oryzanol, that is a 40:60 weight ratio. With increasing
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temperatures, the progressive dissolution of sitosterol and oryzanol tubules leads to the
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gel melting (Bot & Flöter, 2011).
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Apart from the good structuring properties, phytosterol-based organogels are
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particularly interesting because phytosterol intake by foods is associated with a
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significant LDL-cholesterol lowering. For the recommended intake of 2 g/day, a 9%
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lowering of LDL-cholesterol is expected (Demonty et al., 2009).
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Notwithstanding the high interest in food-grade organogels meant by the packed
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literature in this field, few papers deal with oleogel applications in real food systems
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(Aguirre-Mandujano, Lobato-Calleros, Garcia, & Vernon-Carter, 2009; Calligaris,
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Manzocco, Valoppi, & Nicoli 2013; Goldstein & Seetharaman, 2011; Manzocco,
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Anese, Calligaris, Quarta, & Nicoli, 2012; Stortz et al., 2012). Only Zulim-Botega,
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Marangoni, Smith, and Goff (2013a,b) studied the application of oleogels in ice cream.
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In particular, performances of rice bran wax, candelilla wax, or carnauba wax oleogels
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in ice creams formulated with 10 or 15 g/100 g fat were evaluated. They demonstrated
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ACCEPTED MANUSCRIPT the potentials of rice bran wax oleogels to develop fat structure in ice cream with high
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fat concentration (15 g/100 g), in the presence of glycerol monooleate as emulsifier.
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The aim of this work was to study the possibility of producing healthier artisanal ice
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creams by substituting milk cream with phytosterol organogel systems based on
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sunflower oil. In particular, a cold-pressed sunflower oil was used, in order to reduce
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the amount of saturated fatty acids brought in the final product and to enrich the ice
97
cream in antioxidant compounds (i.e., α- and β-tocopherol). Quality features of ice
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creams were studied as a function of the amount (4 and 8 g/100 g) and type of fat used
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(milk cream, sunflower oil, and organogels containing two different levels of gelators),
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as well as of their interaction.
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2. Materials and methods
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2.1 Organogel preparation
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In organogel (OG) preparation the following ingredients were used: cold-pressed
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sunflower oil kindly supplied by Il frutteto Incantato di Montefiore (Recanati, Italy), γ-
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orizanol (Sochim International, Cornaredo, Italy), and phytosterol complex concentrate
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95% (Sochim International). The cold-pressed sunflower oil had a saturated fatty acid
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level of 10.2%, and a α- and β-tocopherol content of 540 mg/kg and 25 mg/kg,
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respectively. The phytosterol concentrate contained β-sitosterol (51.62 g/100 g),
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campesterol (21.85 g/100 g), stigmasterol (21.23 g/100 g), brassicasterol (1.13 g/100 g),
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β-sitostanol (0.81 g/100 g), campestanol (0.49 g/100 g), and other sterols and stanols
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(2.87 g/100 g).
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ACCEPTED MANUSCRIPT Two levels of gelators were considered in OG production: 8 g/100 g (OG_8) or 12
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g/100 g (OG_12) on oil basis. Gelators consisted of a phytosterol concentrate and γ-
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orizanol mixture in 40:60 weight ratio.
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Sunflower oil was warmed up to 70 °C in a thermostatic bath; then the given amount of
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gelators was added under continuous stirring. The stirring phase lasted for 35 min, until
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the total dissolution of gelators in the oil. Then, the hot mixture of oil and gelators was
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added to ice cream mix during pasteurization as described in §2.3. Since the application
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of a heating-cooling temperature cycle causes the gelator tubules to dissolve and reform
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(Bot, den Adel, Regkos, Sawalha, Venema, & Flöter, 2011), the cooling phase
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necessary to the formation of the OG was not carried out because the addition of the
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lipid phase to the ice cream mix during heating would have dissolved the gel in any
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case. The typical tubules of this kind of OG were supposed to form during cooling of
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the ice cream mix, as already demonstrated for oil in water (o/w) emulsions: the initial
126
creation of the emulsion can be done more or less independently from a later formation
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of the OG network in the lipid phase (Duffy, Blonk, Beindorff, Cazade, Bot, &
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Duchateau, 2009).
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2.2. Ice cream formulations
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Experimental ice creams were formulated as reported in Table 1, varying the amount of
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fat (4 or 8 g/100 g) and keeping constant the quantity of added sugars (14.9 g/100 g)
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and total solids (30.6 ± 0.3 g/100 g). Fresh pasteurized skim milk (Centrale del Latte di
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Milano, Milan, Italy) and pasteurized milk cream (Centrale del Latte di Milano, Milan,
135
Italy) were purchased from a local supermarket, while all the powder ingredients were
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35.0 g/100 mL fat, 68% of which were saturated fatty acids.
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Experimental samples were identified by a code consisting of two letters and two
139
numbers: the letters refer to the type of fat used (MC, milk cream; OG, organogel; SO,
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sunflower oil), the first number to the amount of fat in the formulation (4 or 8 g/100 g),
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and the second number to the percentage of gelators used for oil structuring (8 or 12
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g/100 g on oil basis).
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2.3. Ice cream production
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Ice cream mixes were prepared as reported by Rossi, Alamprese, Casiraghi, and Pompei
146
(1999), by using a Pastomaster 60 Tronic and a Labotronic 20-30 batch freezer
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(Carpigiani S.r.l, Anzola Emilia, Italy). Briefly, liquid ingredients were heated up to 50
148
°C before the addition of solid ingredients. SO and OG, when present, were added to
149
milk during heating just before the solid ingredient addition. The mix (15 kg) was then
150
pasteurised at 85 °C for about 1 min and aged at 4 °C for 24 h. Mix freezing was carried
151
out in 3 L batches, measuring ice cream extrusion time using a chronometer.
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Immediately after extrusion, ice cream temperature was evaluated by a thermometer
153
inserted in the centre of the product. After packaging, ice cream samples were stored for
154
24 h at -30 °C and then conditioned for 24 h at -16 °C before analyses. Two
155
technological replicates were carried out for each formulation.
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2.3. Ice cream mix analyses
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Ice creams mixes were characterized in terms of viscosity, density and soluble solids as
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reported by Moriano and Alamprese (2017). In particular, viscosity was evaluated in
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(Anton Paar, Graz, Austria) equipped with a cone-plate geometry (CP50-1), ranging
162
shear rate from 20 to 500 s-1. Results are expressed as the average of two technological
163
replicates in terms of apparent viscosity (mPa s) at 290 s-1. This value of shear rate was
164
chosen because it represents an average pipe wall shear rate during fluid food pumping
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(Alamprese, Pompei, & Guatelli, 2001). Moreover, consistency coefficient (K; mPa sn)
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and flow behaviour index (n; dimensionless) were calculated by fitting flow curves with
167
the power law equation (Steffe, 1996).
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2.4. Ice cream analyses
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Analyses of ice cream quality characteristics were carried out as reported in Alamprese,
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Foschino, Rossi, Pompei, and Savani (2002), and in Moriano and Alamprese (2017).
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Overrun is reported as the percentage of mix volume increase during freezing, measured
173
on ten 230 mL samples for each production. Firmness was determined by an Instron
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Universal Testing Machine (Mod. 4301, Instron Ltd., High Wycombe, UK) performing
175
penetration tests on 50 mL samples. A stainless steel cylindrical probe (8 mm diameter)
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connected to a 100 N load cell was used, penetrating ice cream samples for 18 mm,
177
using a crosshead speed of 50 mm/min. Results, expressed as the maximum load (N)
178
opposed by ice cream to a 15 mm penetration, are the average of at least ten
179
measurements for each production. Melting behaviour, reported as melting starting time
180
and melting rate, was evaluated at 20 °C on 230 mL ice cream samples, recording the
181
weight of melted ice cream (g) as a function of time (up to 90 min). Results are the
182
average of three replicates for each production. During melting tests, pictures of the
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samples were taken every 15 min and elaborated by a purposely developed image
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The following shape retention indexes were calculated: Rt/R0, ratio between sample
186
height and width at different times (0, 15, 30, 45, 60, 75, 90 min) referred to the ratio at
187
the initial time (0 min); At/A0, ratio between the area at each time referred to the area at
188
the initial time. Ice cream colour was measured using a reflectance colorimeter Chroma
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Meter CR 210 (Minolta Camera Co. Ltd, Tokio, Japan), with standard illuminant C.
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CIE L*a*b* indexes are reported as the average of nine determinations, carried out on
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three 230 mL samples of each production.
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2.5. Statistical analysis
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Two-way analysis of variance (ANOVA) was applied to the analytical data in order to
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study the effects of the two considered factors: amount of fat (4 g/100 g and 8 g/100 g)
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and type of fat (MC, SO, OG_8, and OG_12). The interaction term (fat amount × fat
197
type) was also considered in ANOVA; it has not been reported in result tables, but
198
commented in the text only when significant (p < 0.05). The Least Significant
199
Difference (LSD) test at p < 0.05 was used to evaluate significant differences among the
200
averages (Statgraphics Plus 5.1, Statistical Graphics Corp., Herndon, VA, USA).
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3. Results and discussion
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3.1. Ice cream mix properties
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Results of ice cream mix characteristics and LSD test after two-way ANOVA are shown
205
in Table 2. Formulations with higher amount of fat showed significantly (p < 0.05)
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decreased mix density and soluble solid content, due to the lower density of fat with
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respect to the serum phase and the lower level of milk solids not fat (MSNF; Table 1).
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209
the exception of OG_12 that led to a significantly (p < 0.05) higher Brix degree value,
210
probably ascribable to gelators.
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Rheological behaviour of ice cream mixes was mainly affected by fat type rather than
212
amount. In particular, the use of SO or OG_8 significantly (p < 0.05) decreased the
213
apparent viscosity and the consistency coefficient of the mixes with respect to samples
214
containing MC or OG_12. This result is related to the higher amount of saturated fatty
215
acids in MC, yielding higher proportions of crystallized fat at 4 °C with respect to those
216
of samples containing SO or OG_8. OG_12 showed a higher structuring effect with
217
respect to OG_8, resulting in an apparent viscosity of ice cream mixes not significantly
218
(p > 0.05) different from that of samples made with MC. This result revealed that an
219
OG network was actually created in the ice cream mix containing OG_12, increasing
220
the apparent viscosity of the system. The higher amount of gelators needed to structure
221
sunflower oil in the ice cream emulsion is in agreement with previous findings by
222
Sawalha, den Adel, Venema, Bot, Flöter, and van der Linden (2012), who reported that
223
in the emulsion, the water molecules bind to the β-sitosterol molecules, forming
224
monohydrate crystals that hinder the formation of the tubules thus resulting in a weaker
225
emulsion-gel.
226
Sunflower oil is a Newtonian fluid, thus its flow behaviour index (n) is equal to 1.
227
Rheology of sunflower oil affected the rheological behaviour of ice cream mixes
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containing this type of fat (structured or not). Indeed, ice cream mixes SO, OG_8, and
229
OG_12 showed significantly (p < 0.05) higher values of n with respect to samples
230
produced with MC. As it is shown in Fig. 1, the behaviour of mixes containing OG with
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12 g/100 g gelators (OG4_12 and OG8_12) was more similar to those produced with
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MC rather than to samples made with SO or OG_8, in agreement with the higher
233
structuring ability of the higher gelator concentration.
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3.2. Quality characteristics of ice creams
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No significant (p > 0.05) differences were measured in extrusion time and temperature
237
of ice cream samples as a function of fat amount or type. All ice cream mixes were
238
extruded in 7.8 ± 0.2 min, reaching a temperature of -7.9 ± 0.4 °C. On the contrary, both
239
the considered factors significantly (p < 0.05) affected quality characteristics of ice
240
creams in terms of overrun and melting behavior (Table 3). As already observed in
241
previous works (Alamprese et al., 2002; Roland, Philips, & Boor, 1999; Zulim-Botega
242
et al., 2013b), a higher amount of fat accounted for a lower overrun and melting rate.
243
This can be related to the corresponding lower level of MSNF in the ice creams (Table
244
1), bringing in the product less proteins and consequently modifying whipping
245
properties of mix and melting behavior of the final product (Goff, 1997). As regards the
246
type of fat, SO and OG_8 worsened the ice cream overrun with respect to MC, while
247
the use of OG_12 resulted in an overrun even higher than that of the ice cream
248
containing MC. Moreover, in comparison with MC samples, ice creams made with
249
OG_12 showed a significantly (p < 0.05) higher melting starting time and a similar
250
melting rate. Thus, it can be concluded that the use of OG_12 accounted for an
251
improvement in ice cream quality characteristics with respect to the use of non-
252
structured SO. This can be related to the higher ratio of solid:liquid fat attained during
253
mix ageing, since, as reported by Goff (1997), a partially crystalline emulsion is needed
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for partial fat coalescence in the whipping and freezing steps, leading to air bubble
255
stabilization and, as a consequence, to higher overrun and melting resistance. Similar
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a rice bran wax oleogel instead of high oleic sunflower oil improves overrun and
258
melting rate of ice cream.
259
The fat amount effect on ice cream firmness was not in agreement with previous papers
260
reporting a higher softness with the increasing of fat content (Alamprese et al., 2002;
261
Roland et al., 1999). However, it has to be highlighted that the formulation balancing is
262
very important to this aspect. In this work, mix total solids have been kept constant,
263
meaning that in recipes with a low amount of fat there was a higher content of MSNF
264
(Table 1) including also lactose and minerals. According to the Raoult’s law, a higher
265
molar fraction of low molecular weight solutes accounts for a higher freezing point
266
depression effect (LeBail & Goff, 2008). This means that at a given temperature ice
267
creams with higher MSNF concentration (corresponding in this research to the samples
268
with lower amount of fat) will have a higher amount of unfrozen water, thus justifying
269
the lower ice cream firmness.
270
The interaction term fat amount × type was also significant (p < 0.05). Actually, looking
271
at each fat type separately (Table 4), the increase in fat amount always yielded firmer
272
ice creams, with the exception of the samples containing SO. In this case, it is likely that
273
the lower amount of solid fat at the temperature of analysis (-16 °C) caused the lower
274
ice cream firmness.
275
All the ice cream samples showed a good shape retention during melting (Fig. 2).
276
However, the significantly (p < 0.05) highest Rt/R0 values were obtained with the use of
277
OG_12, confirming the good performance of this type of fat in comparison with SO and
278
even MC, the latter resulting in ice creams with significantly (p < 0.05) lower Rt/R0
279
values (Figs. 3A and 3B). The higher fat amount accounted for significantly (p < 0.05)
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281
these samples (Table 3).
282
Color of ice cream samples was measured in order to highlight possible effects of the
283
different fat types and amounts used. In all samples, L* values ranged from 93.0 to
284
95.3, a* from -3.9 to -2.9, and b* from 5.3 to 6.4. No significant (p > 0.05) differences
285
were observed. Thus it can be concluded that the different color of MC with respect to
286
SO and OG did not modify visual appearance of ice creams.
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4. Conclusions
289
In conclusion, the application of organogels in artisanal ice creams as milk cream
290
substitutes is a successful approach in order to obtain healthier products. In particular,
291
ice creams produced with OG containing 12 g/100 g gelators showed similar or even
292
better quality characteristics with respect to samples made with MC.
293
Ice creams produced with 4 or 8 g/100 g OG contained 0.48 g/100 g and 0.86 g/100 g
294
saturated fats, respectively, representing about 3 and 5% of the total energy content of
295
the products. Thus, in agreement with Regulation (EC) No 1924/2006, they can be
296
claimed as “low saturated fat” ice creams. Actually, the Regulation states that the claim
297
can be used if the sum of saturated fatty acids and trans-fatty acids in the product does
298
not exceed 1.5 g/100 g for solids and does not provide more than 10% of energy. In MC
299
samples, saturated fatty acids ranged from 2.74 to 5.47 g/100 g as a function of the fat
300
amount.
301
Moreover, because of the presence of phytosterols and phytostanols, the label of ice
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creams containing OG shall contain the words “with added plant sterols and plant
303
stanols”, the amount of phytosterols and phytostanols used as ingredients, and a
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cholesterol level (Commission Regulation (EC) No 608/2004). Considering an average
306
ice cream serving portion of 150 g, the developed products does not exceed the limit
307
about the consumption of no more than 3 g/day of added plant sterols/stanols stated by
308
the European legislation.
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Acknowledgements
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This work was supported by the Italian Association of Food Product Industries (AIIPA)
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- “Artisanal Ice Cream Ingredients” Group.
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395
Figure 1. Flow curves (mean of two technological replicates) of ice cream mixes
396
produced with milk cream (MC; ◊), sunflower oil (SO; □), organogel with 8 g/100 g
397
gelators (OG_8; ∆) and organogel with 12 g/100 g gelators (OG_12; ○), containing 4
398
g/100 g fat (A) and 8 g/100 g of fat (B). Standard deviation values ranged from 0.9 to
399
6.8 mPa s.
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Figure 2. Examples of pictures taken during melting test of ice creams containing 4
402
g/100 g fat, produced with milk cream (MC4), sunflower oil (SO4), organogel with 8
403
g/100 g gelators (OG4_8), and organogel with 12 g/100 g gelators (OG4_12). The
404
pictures are taken at the beginning of the test (T0) and after 30 (T30), 60 (T60), and 90
405
(T90) minutes.
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Figure 3: Shape retention indexes (Rt/R0 and At/A0) as a function of melting time of ice
408
creams produced with milk cream (MC; ◊), sunflower oil (SO; □), organogel with 8
409
g/100 g gelators (OG_8; ∆) and organogel with 12 g/100 g gelators (OG_12; ○),
410
containing 4 g/100 g fat (A, C) and 8 g/100 g of fat (B, D). Error bars represent standard
411
deviation values of two technological replicates. Rt/R0, ratio between ice cream sample
412
height and width at different times of melting referred to the ratio at the initial time;
413
At/A0, ratio between ice cream sample area at different times of melting referred to the
414
area at the initial time.
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Table 1. Formulation and composition of ice cream samples produced in order to study the effect of fat amount and type MC8
SO4
SO8
OG8_8
OG4_12
OG8_12
75.2 3.9 5.4 12.0 2.9 0.2 0.4
75.2 7.9 1.4 12.0 2.9 0.2 0.4
75.2 3.9 5.4 12.0 2.9 0.2 0.4
75.2 7.9 1.4 12.0 2.9 0.2 0.4
4.0 0.5 14.9 11.2 30.3
8.0 0.9 14.9 7.7 30.8
4.0 0.5 14.9 11.2 30.3
8.0 0.9 14.9 7.7 30.8
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Ingredients (g/100 g) Fresh skim milk 67.9 60.3 75.2 75.2 Fresh milk cream 11.2 22.8 Sunflower oil 3.9 7.9 Organogel 8 g/100 g gelators Organogel 12 g/100 g gelators Skim milk powder 5.4 1.4 5.4 1.4 Sucrose 12.0 12.0 12.0 12.0 Dextrose 2.9 2.9 2.9 2.9 Whey proteins 0.2 0.2 0.2 0.2 Stabilizers & Emulsifiers 0.4 0.4 0.4 0.4 Composition (g/100 g) Fat 4.0 8.0 4.0 8.0 of which saturated 2.7 5.5 0.5 0.9 Added sugars 14.9 14.9 14.9 14.9 MSNF 11.2 7.8 11.2 7.7 Total solids 30.4 31.0 30.3 30.8 MSNF, milk solids not fat; MC, milk cream; SO, sunflower oil; OG, organogel.
OG4_8
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ACCEPTED MANUSCRIPT Table 2. Results of ice cream mix properties (mean ± standard error values of two technological replicates) as a function of the two experimental factors studied: fat amount and type.
Density (g/mL)
Soluble solids (°Bx)
Apparent viscosity (mPa s)
K (mPa sn)
n (-)
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Fat amount (g/100 g) 4 30.1±0.3b 29.9±0.5a 78±3a 0.831±0.005a 1.10±0.01b a a a a 8 1.08±0.01 27.2±0.3 29.5±0.5 74±3 0.848±0.004b Fat type MC 1.08±0.01a 28.5±0.4a 32.2±0.7b 102±4c 0.799±0.006a SO 1.09±0.01a 28.0±0.4a 27.6±0.7a 66±4a 0.848±0.007b a a a a OG_8 28.0±0.4 27.1±0.7 60±4 0.862±0.007b 1.09±0.01 OG_12 1.09±0.01a 30.2±0.4b 31.9±0.7b 76±3b 0.850±0.005b MC, milk cream; SO, sunflower oil; OG_8, sunflower oil-based organogel with 8 g/100 g gelators; OG_12, sunflower oil-based organogel with 12 g/100 g gelators; K, consistency index; n, flow behavior index. a-c within the same factor, results with different superscript letters in the same column are significantly different (p < 0.05) on the basis of two-way ANOVA followed by the Least Significant Difference test.
ACCEPTED MANUSCRIPT Table 3. Results of quality characteristics of ice cream samples (mean ± standard error values of two technological replicates) as a function of the two experimental factors studied: fat amount and type.
Overrun (%)
Firmness (N)
Melting behaviour
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Factors
ts (min)
rate (g/min)
AC C
EP
TE D
M AN U
SC
Fat amount (g/100g) 4 37.3±0.6b 12.7±0.7a 18±1a 2.9±0.1b 8 15.4±0.7b 19±1a 2.5±0.1a 31.1±0.6a Fat type MC 37.1±0.8b 14±1a 16±1a 2.28±0.09a a a b SO 27.5±0.8 13±1 20±1 2.83±0.09b OG_8 29.9±0.8a 14±1a 18±1ab 2.98±0.09b OG_12 42.4±0.8c 15±1a 20±1b 2.67±0.09ab MC, milk cream; SO, sunflower oil; OG_8, sunflower oil-based organogel with 8 g/100 g gelators; OG_12, sunflower oil-based organogel with 12 g/100 g gelators; ts, starting time. a-b within the same factor, results with different superscript letters in the same column are significantly different (p < 0.05) on the basis of two-way ANOVA followed by the Least Significant Difference test.
ACCEPTED MANUSCRIPT Table 4. Firmness (mean ± standard error values of two technological replicates) of ice cream samples produced with different fat amount and type. Fat amount Type of fat Firmness (g/100 g) (N) MC4 4 MC 13±1 MC8 8 MC 15±1 SO4 4 SO 14±2 SO8 8 SO 11±2 OG4_8 4 OG_8 12±1 OG8_8 8 OG_8 16±1 OG4_12 4 OG_12 11±1 OG8_12 8 OG_12 18±1 MC, milk cream; SO, sunflower oil; OG_8, sunflower oil-based organogel with 8 g/100 g gelators; OG_12, sunflower oil-based organogel with 12 g/100 g gelators. See Table 1 for ice cream sample formulations.
AC C
EP
TE D
M AN U
SC
RI PT
Sample
ACCEPTED MANUSCRIPT Figure 1 65
65
A
B
60
50 45 40 35 30 25
55 50 45 40 35 30 25
20
20 200 400 Shear rate (s-1)
600
0
200 400 Shear rate (s-1)
600
M AN U
SC
0
RI PT
55
Viscosity (mPa·s)
Viscosity (mPa·s)
60
Figure 1 – color version for web only
65
65
A
TE D
50 45 40 35 30 25 20
200 400 Shear rate (s-1)
AC C
0
60
Viscosity (mPa·s)
55
EP
Viscosity (mPa·s)
60
B
55 50 45 40 35 30 25 20
600
0
200 400 Shear rate (s-1)
600
ACCEPTED MANUSCRIPT Figure 2.
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
AC C
EP
TE D
M AN U
SC
RI PT
1 cm
1 cm
1 cm
ACCEPTED MANUSCRIPT Figure 3 1.20
1.20
B
1.00
1.00
0.80
0.80
0.60
0.60
0.40
0.40
0.20
0.20
0.00
0.00 0
15
30
45 60 Time (min)
75
90
0
15
C 0.80
0.80
At/A0
M AN U
1.00
At/A0
1.00
0.60 0.40
45 60 Time (min)
75
SC
1.20
1.20
30
RI PT
Rt/R0
Rt/R0
A
90
D
0.60 0.40
0.20
0.20
0.00
0.00
15
30
45 60 Time (min)
75
90
0
15
30
45 60 Time (min)
75
TE D
0
90
Figure 3 – color version for web only 1.20
1.20
A
0.40 0.20 0.00 0
AC C
0.60
15
30
45 60 Time (min)
0.80
Rt/R0
0.80
Rt/R0
B
1.00
EP
1.00
0.60 0.40 0.20 0.00
75
90
0
1.20
15
30
45 60 Time (min)
75
1.20
C
D
1.00
1.00
0.80
0.80
At/A0
At/A0
90
0.60
0.60
0.40
0.40
0.20
0.20
0.00
0.00 0
15
30
45 60 Time (min)
75
90
0
15
30
45 60 Time (min)
75
90
ACCEPTED MANUSCRIPT
Highlights Organogels and milk cream led to ice cream mix with similar density and viscosity.
RI PT
Organogels produced ice cream with better overrun and melting starting time.
AC C
EP
TE D
M AN U
SC
Fat amount affected sample density, soluble solids, overrun and melting rate.