Research Article Received: 1 November 2013
Revised: 17 March 2014
Accepted article published: 24 March 2014
Published online in Wiley Online Library: 23 April 2014
(wileyonlinelibrary.com) DOI 10.1002/jsfa.6674
Physical properties of sugar cookies containing chia–oat composites George E Inglett,* Diejun Chen and Sean Liu Abstract BACKGROUND: Omega-3 fatty acids of chia seeds (Salvia hispanica L.) and soluble 𝜷-glucan of oat products are known for lowering blood cholesterol and preventing coronary heart disease. Nutrim, oat bran concentrate (OBC), and whole oat flour (WOF) were composited with finely ground chia, and used in cookies at 20% replacement of wheat flour for improved nutritional and physical quality. The objective was to evaluate physical properties of chia–oat composites, dough, and cookies. RESULTS: These composites had improved water-holding capacities compared to the starting materials. The geometrical properties and texture properties of the cookies were not greatly influenced by a 20% flour replacement using chia–OBC or chia–WOF composites. There was a decrease in the cookie diameter, and increases in the height of cookies and dough hardness using 20% Chia- Nutrim composite. CONCLUSION: These fine-particle chia–oat composites were prepared by a feasible procedure for improved nutritional value and physical properties of foods. The cookies containing chia–oat composites can be considered a health-promoting functional food. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. Keywords: chia; oat; physical properties; pasting; rheology; cookies
INTRODUCTION
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Chia (Salvia hispanica L.) is an annual herbaceous plant that belongs to the Lamiaceae family and is native to southern Mexico and northern Guatemala.1 Chia, also known as chia sage and Spanish sage, has been an important staple food in such products as gruel with roasted and ground chia seeds; used in flavorings; as an oil source, e.g. as body emollient; in painting oil; and in folk medicine for treating eye obstructions, infections, and respiratory malaises.2,3 The chia plant produces numerous small white or dark seeds having high unsaturated oil content that are useful as a dietary supplement.4 The seeds soaked in water or fruit juice are consumed in some regions as refreshing drinks.5 Recent studies have shown that chia has a high content of oil (320 g kg−1 ) that is rich in polyunsaturated fatty acids, particularly 𝜔-3 linolenic acid (540–670 g kg−1 ) and 𝜔-6 linoleic acid (120–210 g kg−1 ), which has benefits for human and animal health;6,7 soluble and insoluble dietary fiber (over 300 g kg−1 of the total weight), both important components of the human diet; and proteins of high biological value (around 190 g kg−1 of the total weight).8,9 In addition, the seed contains natural antioxidants such as phenolic glycoside-Q and K, chlorogenic acid, caffeic acid, quercetin, and kaempferol,10 which protects consumers against some adverse conditions, such as some cardiovascular diseases and some types of cancers; as well as supplying vitamins and minerals.11 – 13 Also, chia seeds contain 50–60 g kg−1 mucilage that can be used as dietary fiber.10,14 Defatted chia has 220 g kg−1 fiber and 170 g kg−1 protein, similar to other oilseeds, and has been used in food and animal feed.15 The protein content of chia is higher than that of many traditional grains such as wheat, corn, rice, oat, barley and amararanth.16 Chia protein contains high amounts of glutamic J Sci Food Agric 2014; 94: 3226–3233
acid (123 g kg−1 raw protein), arginine (80.6 g kg−1 raw protein), and aspartic acid (61.3 g kg−1 raw protein). Its amino acid profile has no limiting factors in the adult diet, but threonine, lysine, and leucine were the limiting amino acids in a preschool child’s diet.17 The quality, yield, and composition of some minor constituents of chia seed oils are influenced by the extraction process. Solvent extraction yields about 30% more oil than by pressing. The main fatty acids, ranked in the following order of abundance, are: 𝛼-linolenic acid > linoleic acid > oleic acid ≈ palmitic acid > stearic acid, for both extraction systems.7 Oat products are recognized for containing 𝛽-glucan soluble fiber, which has beneficial health effects on coronary heart disease prevention by reducing serum cholesterol and postprandial serum glucose levels.18 Therefore, several oat hydrocolloids including Nutrim have been developed and patented using mechanical shearing and steam jet cooking to increase the 𝛽-glucan content in oat products.19,20 Oat hydrocolloid products containing 𝛽-glucan have numerous functional food applications to reduce fat content and calories in a variety of foods;21 control the rheology and texture of food products;22 modify starch gelatinization and retrogradation;23,24 and also provide freezing/thawing stability.25 It was reported that a 5% dispersion of Nutrim had the same
∗
Correspondence to: George E Inglett, USDA, Functional Foods Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, 1815 N University Street, Peoria, IL 61604, USA. E-mail: [email protected] Functional Foods Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, Peoria, IL 61604, USA
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Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
Physical properties of sugar cookies containing chia–oat composites consistency as coconut cream when used in several Thai desserts.26 In addition, fat in muffins and frozen desserts could be replaced with Nutrim, and the effect on their flavor and texture was evaluated.27 A recent study showed that shortening in cakes could be substituted with up to 40% Nutrim without loss of cake quality.21 Rheological and physical evaluation of jet-cooked oat bran has been studied in low-calorie cookies by replacing 20% of the shortening with oat 𝛽-glucan hydrocolloids.28 Cookies containing another oat hydrocolloid (20% 𝛽-glucan) exhibited reduced spreading characteristics and increased elastic properties compared with the control. The study suggested that the replacement should be limited to less than 50% of the substitution for butter and coconut cream in bakery products.29 Although chia seeds are an excellent source of 𝜔-3 oil, the viscosity and cohesion of ground chia is fairly low for food applications.15,30,31 There is a need for improvement in the functional performance of ground chia seeds. Ground chia seeds, containing 𝜔-3 oil, were used in combination with Nutrim, oat bran concentrate (OBC), and whole oat flour (WOF) containing 𝛽-glucan to produce chia–oat composites, described in a patent application by Inglett and Chen.30 The oat component appeared to be helpful in absorbing chia oil and improving physical properties. The physical properties of hydrothermal processed chia and oat bran concentrate hydrocolloids were evaluated in an earlier study.31 Also, pasting and rheological properties of ground chia seeds composited with oat products at 1:9, 1:4, and 1:1 ratios were previously investigated.32 These composites had improved water-holding capacities and showed interesting properties. However, chia–oat composites were not studied in food products. In this exploratory study, only the chia–oat composites (1:4) were used and evaluated. The objective of our study was to evaluate the physical properties of newly developed chia–oat composites along with their formulated dough and cookie products. The information could be valuable for developing new functional food products with desirable texture and health benefits.
MATERIALS AND METHODS Chia–oat composites development Black chia seeds (chia) were purchased from Chia Seed Growers (Cuernavaca, Mexico). Organic whole oat flour colloidal fine (WOF) was provided by Grain Millers (Eugene, OR, USA). Oat bran concentrate (OBC) was supplied by Quaker Oats, Chicago, IL, USA (Lot 18608408). Nutrim (Lot 35503475N170) was provided by VDF FutureCeuticals (Momence, IL, USA). Nutrim was prepared by steam jet cooking OBC, sieving, and drum drying.19 All-purpose wheat flour used in the study was produced by General Mills (MN, USA). Black chia seeds were ground for 40 s using a 1095 Knifetec mill (Foss Analytical AB, Sweden). Ground chia seeds were mixed with corresponding oat product using a N-50 Hobart mixer (Hobart Canada Inc., Ontario, Canada) for 1 min. The mixtures were ground again with a 1095 Knifetec mill for another 40 s for additional mixing to obtain the desired fine composites.
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Cookie preparation Cookies were prepared following AACC methods 10–52 for sugar cookie as described by Lee and Inglett, with modifications.33,34 Sugar (72 g; C&H Sugar Company, Crockett, CA, USA), brown sugar (22.5 g; C&H), non-fat dry milk (2.3 g; Carnation, Nestlé, Vevey, Switzerland), salt (2.8 g), and sodium bicarbonate (2.3 g; Arm & Hammer, Church & Dwight, Co., Inc., Princeton, NJ, USA) were mixed. The mixture was transferred on top of shortening (100 g, Crisco, JM Smucker Company, Orrville, OH, USA) and blended with a paddle beater in a mixing bowl using a KitchenAid mixer (St Joseph, MI, USA) at speed 2 for 3 min, scraping down every minute. Water (49.5 g) containing ammonium bicarbonate (1.1 g, Calumet, Kraft, Northfield, IL, USA) was added and mixed for 1 min at speed 1. After scraping down, the contents were mixed for another minute at speed 2. Flour or flour containing chia–oat composites were added while mixing at speed 1, and mixing was continued for 2 min at speed 2 with scraping every 30 s. Dough was flattened by using a rolling pin on an aluminum pan with 7 mm gauge strips, and cut with a cookie cutter of 6 cm diameter. Cookies were baked at 205 ∘ C in a convection oven (XAF-113 LineChef Stefania, Cadco Ltd, Winsted, CT, USA) for 10 min and cooled. The cookies were stored in a sealed plastic bag until measurements were taken. Water loss, moisture content and water activity Water losses during baking were measured by the weight of the difference before and after baking. After grinding three cookies with a pestle in a mortar, moisture content and water activity were measured. Moisture contents of cookies were determined by drying 5 g of sample at 105 ∘ C to a constant weight (about 3–4 h). The water activity was measured using an Aqua Lab water activity meter (Decagon Devices Inc., Pullman, WA, USA). Geometrical properties Six cookies were placed next to each other and the total diameter was measured. They were rotated by 90∘ and measured again. After repeating two more times, the average of four measurements was divided by six to calculate the average diameter of a cookie. To measure the height, six cookies were stacked, measured, restacked in a different order, and measured again. The average cookie height cookie was the mean of three readings divided by six. The spread ratio was calculated by dividing the diameter by the height. Nine measurements for each replicate were taken (n = 9). Color The color of the cookies was measured with a Hunter Lab spectrocolorimeter (Labscan XE, Hunter Associates Laboratory Inc., Reston, VA, USA). The colorimeter was calibrated using a standard white plate. The color values L*, a*, b* were measured with a C illuminant and a 10∘ standard observer. The dimension L* indicates lightness, with 100 for white and 0 for black; a* indicates redness when positive and greenness when negative; b* indicates yellowness when positive and blueness when negative. Texture analysis Cookie hardness was measured using recommended methods of TA-XT2 Texture Analyzer (Texture Technology Crop., Scarsdale, New York, USA) equipped with 30 kg load cell. The cookie hardness measurement was conducted by a cutting force using a
Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
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Cookie flour formulations Cookie flour formulations were as follows: (i) wheat flour only (control); (ii) the wheat flour in cookies was replaced by 20% chia–Nutrim composites 1:4; (iii) the wheat flour in cookies was replaced by 20% chia–OBC composites 1:4; and (iv) the wheat flour in cookies was replaced by 20% of chia–WOF composites 1:4.
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www.soci.org three-point bending method with sharp-blade probe, 6 cm long and 1 mm thick. The hardness of the cookies was indicated by the maximum peak force required to break them. The slotted inserts were adjusted and secured on the heavy-duty platform to fit sample size and position centrally under the knife edge. The instrument was set to ‘return to start’ cycle, a pre-test speed of 1.5 mm s−1 , test speed of 2.0 mm s−1 , post-test speed of 10 mm s−1 , and a distance of 5.0 mm. Dough hardness was measured using a TA-XT2 Texture Analyzer equipped with 5 kg load cell in compression mode by penetrating with a flat probe of 5 mm diameter. The cookie dough (110 g) was evenly and gradually placed in a dough cell while compressing and flattening the surface with a plunger to avoid randomly distributed pockets of air as a potential cause of variability in consistency measurements. The test was conducted at a pre- and post-test speed of 2.00 mm s−1 and test speed of 3 mm s−1 , post-test speed of 10.0 mm s−1 , and distance of 20 mm. Water-holding capacity (WHC) WHCs were determined according to the procedure of Ade-Omowave et al., with minor modifications.35 A sample (2 g) was mixed with 25 g distilled water and vigorously mixed using a vortex stirrer for 1 min for a homogenous suspension and then held for 2 h, followed by centrifugation at 1590 × g for 10 min. Each treatment was replicated twice. WHC was calculated using the following equation: ) [ ] ( WHC g kg−1 = water added (g) − decanted water (g) ∕ dry sample weight (g) × 1000 Pasting properties The pasting properties of samples were evaluated using a Rapid Visco Analyzer (RVA-4, Perten Scientific, Springfield, IL, USA). Samples (2.24 g dry basis) were made up to a total weight of 28 g with distilled water in an RVA canister (80 g kg−1 solids, w/w). The viscosity of the suspensions was monitored during the following heating and cooling stages. The suspensions were equilibrated at 50 ∘ C for 1 min, heated to 95 ∘ C at a rate of 6.0 ∘ C min−1 , maintained at 95 ∘ C for 5 min, and cooled to 50 ∘ C at rate of 6.0 ∘ C min−1 , and held at 50 ∘ C for 2 min. For all test measurements, a paddle rotating speed (16.8 rad s−1 ) was maintained constant throughout the entire analysis, except for 96.3 rad s−1 for the first 10 s to disperse sample. Each sample was analyzed in duplicate. The results were expressed in Rapid Visco Analyzer units (RVU, 1 RVU = 12 cP).
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Rheological properties A sample was loaded on a 2 cm diameter X-hatch parallel stainless plate using a rheometer (AR 2000, TA Instruments, New Castle, DE, USA). The outer edge of the plate was sealed with a thin layer of mineral oil (Sigma Chemical Co., St Louis, MO, USA) to prevent dehydration during the test. All rheological measurements were carried out at 25 ∘ C using a water circulation system within ± 0.1 ∘ C. A strain sweep experiment was conducted initially to determine the limits of linear viscoelasticity; then a frequency sweep test was carried out to obtain storage modulus (G′ ) and loss modulus (G′′ ) at frequencies ranging from 0.1 to 10 rad s−1 . A strain of 0.5, which was within the linear viscoelastic range, was used for the dynamic experiments. All rheological measurements for samples were performed in duplicate.
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GE Inglett, D Chen, S Liu Statistical analysis Data were analyzed using SAS software (1999; SAS Institute, Rayleigh, NC, ISA) using analysis of variance with Tukey’s multiple comparison adjustment to determine significant differences (P < 0.05) between treatments.36
RESULTS AND DISCUSSION Water-holding capacity The WHC of the ground chia seeds and their composites with oat products are shown in Table 1. The WHC of chia–Nutrim 1:4 (6110 g kg−1 ) was the highest value among the samples tested, which can probably be attributed to the WHC of chia (4953 g kg−1 ) and Nutrim (5535 g kg−1 ). The WHC of chia–OBC composite (5063 g kg−1 ) was almost twice that of OBC alone (2668 g kg−1 ). The WHC of chia–WOF composite (2903 g kg−1 ) was about twice that of WOF (1330 g kg−1 , similar to the chia–OBC composite and OBC. The high WHC of chia could be attributed to the mucilage found in the outer layers of the chia seed coat.9 When chia seeds contact water, the mucilage appears as a transparent ‘capsule’ surrounding the seed. Chia seeds and their mucilage can be used as a thickener in foods.9 In addition, the WHC of chia could be partially attributed to its protein content, which has a good WHC (4.06 kg kg−1 ) along with an excellent oil retention capacity (4.04 kg kg−1 ).17 All the WHC of oat products (Nutrim, 5535 g kg−1 ; OBC, 2668 g kg−1 ; WOF, 1330 g kg−1 ) were higher than the WHC of wheat flour (753 g kg−1 ). The WHC trend of oat products appears to be related to their 𝛽-glucan contents (Nutrim, 150 g kg−1 ; OBC, 120 g kg−1 ; WOF, 40 g kg−1 ; wheat flour, 12 g kg−1 ), suggesting 𝛽-glucan content may have an important role in WHC. The actual WHCs of chia–oat composites were all slightly higher than the theoretical WHC of the two starting materials (Table 1). It appears that there are interactions between the two starting materials. The improved WHC makes chia–oat composites attractive ingredients for increasing water retention and moisture in bakery and other foods. Pasting properties of composites The pasting curves of the starting materials obtained by RVA are presented in Fig. 1. The Nutrim pasting curves (Fig. 1) exhibited a sharp increase in viscosities during the initial 10 min heating period just before the temperature reached 95 ∘ C, followed by a sharp decrease in viscosity during heating and cooling, showing a considerably lower final viscosity. It is known that the viscosity of completely gelatinized starch slurry decreases during heating.37 These characteristics are common for pre-gelatinized flour38 and
Table 1. WHC of starting materials and chia–oat composites Sample
WHC (g kg−1 )
Wheat flour Chia Nutrim Chia–Nutrim (1:4) OBC Chia–OBC (1:4) Whole oat flour Chia-WOF (1:4)
753 ± 11f 4953 ± 209c 5535 ± 49b 6110 ± 290a 2668 ± 88d 5063 ± 88bc 1330 ± 21e 2903 ± 11d
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
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Physical properties of sugar cookies containing chia–oat composites
Figure 1. Rapid Visco Analyzer pasting curves of starting materials of cookies.
Figure 2. Rapid Visco Analyzer pasting curves of wheat flour, chia, Nutrim and chia–Nutrim composite.
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Figure 3. Rapid Visco Analyzer pasting curves of wheat flour, chia, OBC, and chia–OBC composite.
Figure 4. Rapid Visco Analyzer pasting curves of wheat flour, chia, WOF, and chia–WOF composite.
reaching 95 ∘ C. This may be due to the lower viscosity of ground chia seeds during the initial increasing temperature phase. However, the final viscosity of chia–Nutrim 1:4 was higher than Nutrim, suggesting that it may be related to the higher final viscosity of ground chia seeds during cooling (Fig. 2). A similar trend for the pasting curve (Fig. 3) was observed for chia–OBC composites as for OBC, but chia–OBC composite had higher initial viscosity peak compared to OBC. The initial viscosity from chia–OBC and OBC increased beyond 95 ∘ C and during cooling, resulting in a similar high final peak near 222 RVU. Overall, chia–OBC 1:4 composites had higher final viscosities (Fig. 3, 221.7 RVU) than chia–Nutrim 1:4 (Fig. 2, 54.3 RVU), and chia–WOF composites (Fig. 4, 109.3 RVU). For the chia–WOF 1:4 composite (Fig. 4), viscosities increased gradually during heating. The first peaks were observed at 95 ∘ C followed by a shallow breakdown and final viscosity peak was reached during cooling. Although similar trends were observed for WOF compared with chia–WOF (1:4), the latter had an unexpectedly higher viscosity (109.3 RVU) compared to whole oat flour (77.3 RVU). This could be attributed to the excellent WHC of the chia composites. Moreover, it could be related to the interactions of fiber from both chia and the oat product. All these factors together could play an important role in the interactions, resulting in increasing viscosities.
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typical for Nutrim, since it had undergone hydro-thermal jet cooking in which starch gelatinization occurred. The viscosity of OBC (Fig. 1) increased gradually after heating until reaching 95 ∘ C, and increased continually during cooling, resulting in a considerably higher final viscosity. No dramatic breakdowns (peak viscosity minus the lowest point of viscosity after peak) were observed for OBC. This suggested that 𝛽-glucan in uncooked OBC after heating resulted in an entanglement of molecules during cooling, indicating the formation of a matrix with greater stability under heat and shear. The initial viscosity for WOF (Fig. 1) was increased until the temperature reached 95 ∘ C, showing a lower viscosity peak than Nutrim and OBC but higher than chia, and then slowly increased after a small breakdown similar to OBC. Slowly increasing viscosities of ground chia seeds (Fig. 1) were observed before the temperature reached 95 ∘ C, followed by a continuous increase, and resulting in a final peak that was similar to WOF. Wheat flour (Fig. 1) showed a small initial viscosity peak where the temperature reached 95 ∘ C; viscosities decreased gradually during heating and remained constant during cooling. Wheat flour had the lowest final peak among all the samples. The viscosity curve of chia–Nutrim 1:4 (Fig. 2) had similar patterns to the Nutrim curve (Fig. 2), but the viscosity of chia–Nutrim 1:4 was slightly lower than Nutrim at the initial peak before
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GE Inglett, D Chen, S Liu
Table 2. Geometry properties of cookies Diameter Before bake (mm) Control Chia-Nutrim Chia-WOF Chia-OBC
60 60 60 60
Thickness
After bake (mm)
Increase (mm)
Increase (%)
70.3 ± 0.5a 61.9 ± 0.8c 67.4 ± 0.8b 70.2 ± 0.0a
10.3 ± 0.5a 1.9 ± 0.8c 7.4 ± 0.8b 10.2 ± 0.0a
17.1 ± 0.8a 3.1 ± 0.8c 12.3 ± 0.8b 16.9 ± 0.0a
Before bake (mm) 7 7 7 7
After bake (mm)
Increase (mm)
Increase (%)
Spread ratio
11.8 ± 0.1b 12.0 ± 0. a 11.3 ± 0.2c 11.3 ± 0.2c
4.8 ± 0.1b 5.0 ±0.1a 4.3 ± 0.2c 4.3 ± 0.2c
67.9 ± 1.4b 72.0 ± 1.2a 60.7 ± 3.0c 61.9 ± 2.8c
5.95 ± 0. 21b 5.16 ± 0.25c 5.96 ± 0.26b 6.21± 0.11a
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Table 3. Color profile and water activity of cookies L* Control Chia–Nutrim Chia–WOF Chia–OBC
a*
49.07 ± 0.04a 49.79 ± 0.89a 47.12 ± 0.36b 47.67 ± 0.33b
b*
15.61 ± 0.05a 11.91 ± 0.21d 13.87 ± 0.13b 13.48 ± 0.05c
33.20 ± 0.08a 27.33 ± 0.45c 28.70 ± 0.35b 28.72 ± 0.03b
Water activity (aw ) 0.2400 ± 0.0014c 0.2835 ± 0.0007a 0.2485 ± 0.0007b 0.2060 ± 0.0014d
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Improvements in the textural properties of food using oat 𝛽-glucan hydrocolloids have been reported.39 The RVA data are not only useful for this cookie study but also provide useful information for food processing. Composites having low viscosity may be suitable for products such as nutritional bars. Composites with high initial paste viscosity suggest their uses in food formulations that require little heat during processing, such as beverages. Composites with high viscosities could be used in products such as breads and cookies for increased textural quality and health benefits. Geometrical properties of cookies Cookies containing chia–Nutrim composites had the smallest diameter (61.9 mm) after baking and significantly highest thickness after baking among all the cookies (Table 2). Cookies containing chia–OBC composite had a similar size (70.2 mm) to the control (70.3 mm), which contained wheat flour only. The diameter of the cookie containing chia–WOF composite (67.4 mm) was between the control (70.3 mm) and the cookie containing chia–Nutrim composite (61.9 mm). The spread ratio is the value of the diameter divided by thickness. Chia–OBC composites had the highest spread ratio (6.21). The spread ratio of cookies containing chia–Nutrim composite was the lowest (5.16) among the cookies. The lowest spread value may be related to the high WHC of chia–Nutrim, which had decreased spreading during baking.
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Color of cookies The colors of cookies after baking are shown in Table 3. Cookies containing chia–Nutrim (L* 49.79) and control (L* 49.07) were lighter in color compared with cookies containing chia–OBC (L* 47.67) and chia–WOF (L* 47.12), since the dimension L* indicates lightness, with 100 for white and 0 for black. The value a* indicates redness when positive and greenness when negative. All the cookies showed redness to different degrees. The a* value (15.61) of control cookies was the highest, indicating more redness, and cookies containing chia–Nutrim composite (11.91) revealed the
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least redness. Also, all the cookies showed yellowness to different degrees, since b* indicates yellowness when positive. Similar to the a* value, control cookies (b* 33.20) had the highest value for yellowness among the cookies. Water loss, moisture content of cookies and water activity Among all the cookies, those containing chia–Nutrim composites had the lowest water loss (10.4%) during baking, with the highest cookie moisture content (4.01%) after baking, perhaps because of the high WHC of chia–Nutrim composites. The results of water loss during baking and cookie moisture were consistent with WHCs of cookies (Tables 1 and 4). Water is an important aspect of food stability and shelf-life. The growth and metabolic activities of bacteria, molds, and yeasts are retarded and eventually inhibited as the water activity (aw ) of foods is decreased. Water activity of the cookies prepared with control and cookies containing 20% Nutrim, OBC and WOF were 0.24, 0.28, 0.25, and 0.21 (Table 3), respectively, which were lower than the limit of water activity for spoilage bacteria, yeasts and molds: approximately 0.90, 0.85–0.88, and 0.80, respectively; the rate of chemical reaction in food decreases much more slowly with reduced moisture content, and enzymatic activity in foods may be significant at water activities as low as 0.30.40 Texture of dough and cookies The texture valuations of dough and cookies are presented in Table 4. Dough hardness was tested by a penetrating force using a 5 mm diameter probe. Cookie dough containing chia–Nutrim had a high texture value (0.407 kg), followed by the control (0.344 kg) and cookies containing chia–WOF composites (0.332 kg), with cookies containing chia–OBC having the lowest value (0.298 kg). The highest dough hardness value from cookies containing chia–Nutrim composites may be related to its high WHC. A similar hardness trend was observed for cookies as well as cookie dough (Table 4). Cookies containing chia–Nutrim required the maximum cutting force (5.020 kg) to break the cookie. Again, this may be
Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
J Sci Food Agric 2014; 94: 3226–3233
Physical properties of sugar cookies containing chia–oat composites
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Table 4. Moisture, water loss during baking, and the texture of cookies and dough Water loss during baking (%) Control Chia–Nutrim Chia–WOF Chia–OBC
12.8 ± 0.3a 10.4 ± 0.8c 12.1 ± 0.4b 12.4 ± 0.3b
Cookie moisture (%) 2.33 ± 0.00b 4.01 ± 0.03a 2.38 ± 0.04b 2.02 ± 0.02c
Dough hardness Penetrating force (kg) 0.344 ± 0.024b 0.407 ± 0.009a 0.332 ±0.009cb 0.298 ±0.005c
Cookie hardness Cutting force (kg) 2.174 ± 0.006d 5.020 ± 0.052a 3.137 ± 0.000b 2.466 ± 0.013c
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Figure 5. Dynamic viscoelastic properties of doughs containing chia–oat composites.
due to the high WHC of Nutrim, which resulted in the highest thickness among the cookies (Tables 1 and 2). In contrast, cookies containing chia–OBC composites required the least cutting force to break them. The least cutting force for the cookies containing chia–OBC composites may be related to the thickness (11.3 mm), which was lower among these cookies. Furthermore, the molecular weight for Nutrim at its peak was 3.0 × 105 , which was smaller than that of OBC (1.5 × 106 ), as measured by a size-exclusion chromatography instrument (Shiamdzu, VP series, Tokyo, Japan).41 The high molecular weight of OBC may also be related to cookie texture, which was easier to break down than cookies containing chia–Nutrim composites. The results of dough texture and cookies were in agreement with rheological data (Fig. 5).
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viscous properties.29 The highest values of storage G′ and loss G′′ moduli were observed for dough containing chia–Nutrim composites, followed by dough with chia–WOF, and then control and chia–OBC. The values of storage G′ and loss G′′ moduli for dough containing wheat flour only (control) and chia–OBC dough were almost identical; and both G′ and G′′ were considerably lower than the other two doughs. This indicated that there were insignificant differences on the rheological properties of control dough and dough containing chia–OBC composites. The dough containing chia–Nutrim composite had the most solid properties, followed by dough with chia–WOF composite, control dough, and dough containing chia–OBC composite. Furthermore, these rheological patterns of the chia–oat composites were clearly confirmed by the tan 𝛿 values (G′′ /G′ ) (Fig. 6) because the values of tan 𝛿 indicate the ratio of energy lost to the amount of energy stored during a test cycle. The phase shift 𝛿 is defined by 𝛿 = tan−1 (G′′ /G′ ), which indicates whether a material is solid (𝛿 = 0∘ ), liquid (𝛿 = 90∘ ), or between (0∘ < 𝛿 < 90∘ ). Therefore, the values of tan 𝛿 are from zero to infinity; tan 𝛿 = 1 means G′ = G′′ , tan 𝛿 < 1 represents G′ > G′′ , and tan 𝛿 >1 indicates G′ < G′′ . The tan 𝛿 value has been used to indicate the strong relationship between viscous behavior and the degree of casein hydrolysis.43 In general, the tan 𝛿 values for all doughs were the highest at the lowest frequency and decreased in frequency until it reached 1 rad s−1 . After that, all tan 𝛿 values increased slightly and converged in a tan 𝛿 range from 0.54 (control) to 0.47 (chia–Nutrim). These rheological data appeared to indicate that cookie dough containing chia–oat composites had similar elasticity and stability to the control. This property could provide better shape retention during handling and baking. Because the experimental conditions we adopted were similar to actual processing situations, all our
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Rheological properties of dough The dynamic viscoelastic properties of dough have been related to the quality of baked and other food products.29 G′ , an elastic (storage) modulus, represents the non-dissipative component of the mechanical properties of a material and reflects its elastic characteristics. On the other hand, the viscous (loss) modulus (G′′ ) characterizes the dissipative part of the mechanical properties and represents the viscous flow of the material. G′ and G′′ values against frequency for all the doughs tested are displayed in Fig. 5. Both moduli (G′ and G′′ ) of all samples were increased with increasing frequencies, showing frequency dependence, indicating that these materials could have elastic properties. 42 Moreover, the elastic modulus G′ was higher than the viscous modulus G′′ throughout the frequency range (Fig. 5) for all samples with different levels, suggesting that they had more elastic properties than
Figure 6. Values of tan 𝛿 versus frequency (rad s−1 ) for doughs containing chia–oat composites.
www.soci.org findings on rheological characteristics could be beneficial for processing and developing chia–oat composites for new food applications. The results of the geometry properties of cookies, and the texture of dough and cookies, indicated that cookies formulated with chia–WOF and chia–OBC composites are closer to control values (Tables 2 and 4). It is suggested that chia–WOF and chia–OBC are suitable for bakery products, whereas chia–Nutrim composite could probably be used for beverages and dressings since it has high WHC and high initial viscosity (Fig. 2). The incorporation of chia (Salvia hispanica L.) seeds into baked food products, muffins and cookies has been reported, but the study did not involve oat products. 44 In addition, there are many cookie recipes using whole chia and oatmeal. However, they were not scientifically studied and reported.
CONCLUSIONS The physical properties of chia–oat composites and their use in cookies provide useful information for their potential functional food applications. Chia–oat composites have unique qualities because they provide the oat-soluble fiber 𝛽-glucan, which is beneficial for food texture and for coronary heart disease prevention along with the health benefits of the 𝜔-3 PUFA components of chia. The chia–oat composites are more easily utilized by the human body compared to the whole chia seeds on the market. Chia seeds alone are not easily utilized as food ingredients because of their high oil content and low cohesiveness. Chia–oat composites were created using a feasible dry blending procedure which could maintain the original oat quality along with the lipoidal character and components of the chia. Besides the nutritional aspects of the chia–oat composites, these composites have improved WHC and texture, and useful viscoelastic qualities. Also, our results indicated that the replacement of wheat flour by chia–WOF and chia–OBC composites would not affect the textural quality of cookies. Although chia–oat composites showed differential pasting properties compared with wheat flour, the rheological properties of cookie doughs containing chia–oat composites exhibited similar elastic and stability properties. Chia–Nutrim composites with their excellent WHC may be more suitable for food products, such as cakes. These chia–oat products could have applications for various cookies and other bakery products having improved nutritional value and desirable textural qualities for health-concerned consumers.
REFERENCES
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1 Capitani MI, Spotorno V, Nolasco, SM and Tomás, MC, Physicochemical and functional characterization of by-products from chia (Salvia hispanica L.) seeds of Argentina. LWT – Food Sci Technol 45:94–102 (2012). 2 Lu Y and Foo LY, Polyphenolics of salvia. Phytochemistry 59:117–140 (2002). 3 Jenks AA and Kim SC, Medicinal plant complexes of Salvia subgenus Calosphace: An ethnobotanical study of new world sages. Journal of Ethnopharmacology 146:214–224 (2013). 4 Ayerza R, Oil content and fatty acid composition of chia (Salvia hispanica L.) from five northwestern locations in Argentina. J Am Oil Chem Soc 72:1079–1081 (1995). 5 Cahill JP, Ethnobotany of chia, Salvia hispanica L. (Lamiaceae). Econ Bot 57:604–618 (2003). 6 Rosamond WD, Dietary fiber and prevention of cardiovascular disease. J Am Coll Cardiol 39:57–59 (2002).
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GE Inglett, D Chen, S Liu 7 Ixtaina VY, Martínez ML, Spotorno V, Mateo CM, Maestri DM, Diehl BWK et al., Characterization of chia seed oils obtained by pressing and solvent extraction. J Food Compos Anal 24:166–174 (2011). 8 Taga MS, Miller EE and Pratt DE, Chia seeds as a source of natural lipid antioxidants. J Am Oil Chem Soci 61:928–932 (1984). 9 Muñoz LA, Cobos A, Diaz O and Aguilera JM, Chia seeds: microstructure, mucilage extraction and hydration. J Food Eng 108:216–224 (2012). 10 Reyes-Caudillo E, Tecante A and Valdivia-López MA, Dietary fibre content and antioxidant activity of phenolic compounds present in Mexican chia (Salvia hispanica L.) seeds. Food Chem 107:656–663 (2008). 11 Ayerza R and Coates W, Chia seeds: natural source of omega-3 fatty acids, in Abstracts of the Annual Meeting of the Association for the Advancement of Industrial Crops, Atlanta, GA (2001). 12 Ayerza R and Coates W, Composition of chia (Salvia hispanica) grown in six tropical and subtropical ecosystems of South America. Trop Sci 44:131–135 (2004). 13 Craig R and Sons M, Application for approval of whole chia (Salvia hispanica L.) seed and ground whole chia as novel food ingredients. Advisory committee for novel foods and processes. ACNFP, Food Standards Agency, London, pp. 1–29 (2004). 14 Ayerza R and Coates W, Chia seeds: new source of omega-3 fatty acids, natural antioxidants and dietetic fiber. Southwest Center for Natural Products Research and Commercialization, Office of Arid Lands Studies, Tucson, AZ (2001). 15 Ayerza R and Coates W, An omega-3 fatty acid enriched chia diet: its influence on egg fatty acid composition, cholesterol and oil content. Can J Anim Sci 79:53–58 (1999). 16 Ayerza R and Coates W, Ground chia seed and chia oil effects on plasma lipids and fatty acids in the rat. Nutr Res 25:995–1003 (2005). 17 Olivos-Lugo BL, Valdivia-López MÁ and Tecante A, Thermal and physicochemical properties and nutritional value of the protein fraction of Mexican chia seed (Salvia hispanica L.). Food Sci Technol Int 16:89–96 (2010). 18 Klopfenstein CF, The role of cereal beta-glucans in nutrition and health. Cereal Food Worlds 33:865–869 (1988). 19 Inglett GE, Soluble hydrocolloid food additives and method of making. US Patent 6060519 (2000). 20 Inglett GE, Low-carbohydrate digestible hydrocolloidal fiber compositions. US Patent 7943766B2 (2011). 21 Lee S, Inglett GE and Carriere CJ, Effect of nutrim oat bran and flaxseed on rheological properties of cakes. Cereal Chem 81:637–642 (2004). 22 Rosell CM, Rojas JA and Benedito de Barber C, Influence of hydrocolloids on dough rheology and bread quality. Food Hydrocolloids 15:75–81 (2001). 23 Rojas JA, Rosell CM and Benedito de Barber C, Pasting properties of different wheat flour–hydrocolloid systems. Food Hydrocolloids 13:27–33 (1999). 24 Lee S, Warner K and Inglett GE, Rheological properties and baking performance of new oat 𝛽-glucan-rich hydrocolloids. J Agric Food Chem 53:9805–9809 (2005). 25 Lee MH, Baek MH, Cha DS, Park HJ and Lim ST, Freeze–thaw stabilization of sweet potato starch gel by polysaccharide gums. Food Hydrocolloids 16:345–352 (2002). 26 Maneepun S, Boonpunt T and Inglett GE, Sensory and nutritional evaluation of co-processed Nutrim OB and soy flour in Thai dishes, in 216th ACS National Meeting (AGFD-099), Boston, MA (1998). 27 Warner K and Inglett GE, Flavor and texture characteristics of foods containing nutrim oat bran hydrocolloid, in 216th ACS National Meeting (AGFD-97), Boston, MA (1998). 28 Lee S and Inglett GE, Rheological and physical evaluation of jet-cooked oat bran in low calorie cookies. Int J Food Sci Technol 41:553–559 (2006). 29 Inglett GE, Maneepun S and Vatanasuchart N, Evaluation of hydrolyzed oat flour as a replacement for butter and coconut cream in bakery products. Food Sci Technol Int 6:457–462 (2000). 30 Inglett GE and Chen D, Omega hydrocolloids containing beta-glucan. Patent Application 13/744643 (2013). 31 Inglett GE and Chen D, Processing and physical properties of chia-oat hydrocolloids. J Food Process Pres doi:10.1111/jfpp.12190 (2013). 32 Inglett GE, Chen D, Liu SX and Lee S, Pasting and rheological properties of oat products dry-blended with ground chia seeds. LWT – Food Sci Technol 55:48–156 (2014).
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Physical properties of sugar cookies containing chia–oat composites 33 AACC International, Methods I0-50D and 10-52, in Approved Methods of the American Association of Cereal Chemists (10th edn). AACC International, St Paul, MN (2000). 34 Lee S and Inglett GE, Rheological and physical evaluation of jet-cooked oat bran in low calorie cookies. Int J Food Sci Technol 41:553–559 (2006). 35 Ade-Omowaye BIO, Taiwo KA, Eshtiaghi NM, Angersbach A and Knorr D, Comparative evaluation of the effects of pulsed electric field and freezing on cell membrane permeabilisation and mass transfer during dehydration of red bell peppers. Innov Food Sci Emerg Technol 4:177–188 (2003). ® ® 36 SAS Institute, The SAS system for Windows , version 8e. SAS, Cary, NC (1999). 37 Guha M, Zakiuddin AS and Bhattacharya S, Effect of barrel temperature and screw speed on rapid viscoanalyser pasting behaviour of rice extrudate. Int J Food Sci Technol 3:259–266 (1998). 38 Lai HM and Cheng H-H, Properties of pregelatinized rice flour made by hot air or gum puffing. Int J Food Sci Technol 39:201–212 (2004).
www.soci.org 39 Lee S, Inglett GE, Palmquist D and Warner K, Flavor and texture attributes of foods containing beta-glucan-rich hydrocolloids from oats. LWT – Food Sci Technol 42:350–357 (2009). 40 Smith PG, Applications of Fluidization to Food Processing. Wiley-Blackwell, Chichester, pp. 116–117 (2007). 41 Kim S, Inglett GE and Liu SX, Content and molecular weight distribution of oat 𝛽-glucan in oatrim, nutrim, and C-trim products. Cereal Chem 85:701–705 (2008). 42 Lai LS and Liao C-L, Steady and dynamic shear rheological properties of starch and decolorized Hsian-tsao leaf gum composite systems. Cereal Chem 79:58–63 (2002). 43 Gravier NG, Zaritzky NE and Califano AN, Viscoelastic behavior of refrigerated and frozen low-moisture Mozzarella cheese. J Food Sci 9:23–128 (2004). 44 Devin CL, The incorporation of chia (Salvia hispanica L.) seeds into baked food products. Thesis for Master of Science, University of Florida (2010).
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Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
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Revised: 17 March 2014
Accepted article published: 24 March 2014
Published online in Wiley Online Library: 23 April 2014
(wileyonlinelibrary.com) DOI 10.1002/jsfa.6674
Physical properties of sugar cookies containing chia–oat composites George E Inglett,* Diejun Chen and Sean Liu Abstract BACKGROUND: Omega-3 fatty acids of chia seeds (Salvia hispanica L.) and soluble 𝜷-glucan of oat products are known for lowering blood cholesterol and preventing coronary heart disease. Nutrim, oat bran concentrate (OBC), and whole oat flour (WOF) were composited with finely ground chia, and used in cookies at 20% replacement of wheat flour for improved nutritional and physical quality. The objective was to evaluate physical properties of chia–oat composites, dough, and cookies. RESULTS: These composites had improved water-holding capacities compared to the starting materials. The geometrical properties and texture properties of the cookies were not greatly influenced by a 20% flour replacement using chia–OBC or chia–WOF composites. There was a decrease in the cookie diameter, and increases in the height of cookies and dough hardness using 20% Chia- Nutrim composite. CONCLUSION: These fine-particle chia–oat composites were prepared by a feasible procedure for improved nutritional value and physical properties of foods. The cookies containing chia–oat composites can be considered a health-promoting functional food. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. Keywords: chia; oat; physical properties; pasting; rheology; cookies
INTRODUCTION
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Chia (Salvia hispanica L.) is an annual herbaceous plant that belongs to the Lamiaceae family and is native to southern Mexico and northern Guatemala.1 Chia, also known as chia sage and Spanish sage, has been an important staple food in such products as gruel with roasted and ground chia seeds; used in flavorings; as an oil source, e.g. as body emollient; in painting oil; and in folk medicine for treating eye obstructions, infections, and respiratory malaises.2,3 The chia plant produces numerous small white or dark seeds having high unsaturated oil content that are useful as a dietary supplement.4 The seeds soaked in water or fruit juice are consumed in some regions as refreshing drinks.5 Recent studies have shown that chia has a high content of oil (320 g kg−1 ) that is rich in polyunsaturated fatty acids, particularly 𝜔-3 linolenic acid (540–670 g kg−1 ) and 𝜔-6 linoleic acid (120–210 g kg−1 ), which has benefits for human and animal health;6,7 soluble and insoluble dietary fiber (over 300 g kg−1 of the total weight), both important components of the human diet; and proteins of high biological value (around 190 g kg−1 of the total weight).8,9 In addition, the seed contains natural antioxidants such as phenolic glycoside-Q and K, chlorogenic acid, caffeic acid, quercetin, and kaempferol,10 which protects consumers against some adverse conditions, such as some cardiovascular diseases and some types of cancers; as well as supplying vitamins and minerals.11 – 13 Also, chia seeds contain 50–60 g kg−1 mucilage that can be used as dietary fiber.10,14 Defatted chia has 220 g kg−1 fiber and 170 g kg−1 protein, similar to other oilseeds, and has been used in food and animal feed.15 The protein content of chia is higher than that of many traditional grains such as wheat, corn, rice, oat, barley and amararanth.16 Chia protein contains high amounts of glutamic J Sci Food Agric 2014; 94: 3226–3233
acid (123 g kg−1 raw protein), arginine (80.6 g kg−1 raw protein), and aspartic acid (61.3 g kg−1 raw protein). Its amino acid profile has no limiting factors in the adult diet, but threonine, lysine, and leucine were the limiting amino acids in a preschool child’s diet.17 The quality, yield, and composition of some minor constituents of chia seed oils are influenced by the extraction process. Solvent extraction yields about 30% more oil than by pressing. The main fatty acids, ranked in the following order of abundance, are: 𝛼-linolenic acid > linoleic acid > oleic acid ≈ palmitic acid > stearic acid, for both extraction systems.7 Oat products are recognized for containing 𝛽-glucan soluble fiber, which has beneficial health effects on coronary heart disease prevention by reducing serum cholesterol and postprandial serum glucose levels.18 Therefore, several oat hydrocolloids including Nutrim have been developed and patented using mechanical shearing and steam jet cooking to increase the 𝛽-glucan content in oat products.19,20 Oat hydrocolloid products containing 𝛽-glucan have numerous functional food applications to reduce fat content and calories in a variety of foods;21 control the rheology and texture of food products;22 modify starch gelatinization and retrogradation;23,24 and also provide freezing/thawing stability.25 It was reported that a 5% dispersion of Nutrim had the same
∗
Correspondence to: George E Inglett, USDA, Functional Foods Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, 1815 N University Street, Peoria, IL 61604, USA. E-mail: [email protected] Functional Foods Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, Peoria, IL 61604, USA
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Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
Physical properties of sugar cookies containing chia–oat composites consistency as coconut cream when used in several Thai desserts.26 In addition, fat in muffins and frozen desserts could be replaced with Nutrim, and the effect on their flavor and texture was evaluated.27 A recent study showed that shortening in cakes could be substituted with up to 40% Nutrim without loss of cake quality.21 Rheological and physical evaluation of jet-cooked oat bran has been studied in low-calorie cookies by replacing 20% of the shortening with oat 𝛽-glucan hydrocolloids.28 Cookies containing another oat hydrocolloid (20% 𝛽-glucan) exhibited reduced spreading characteristics and increased elastic properties compared with the control. The study suggested that the replacement should be limited to less than 50% of the substitution for butter and coconut cream in bakery products.29 Although chia seeds are an excellent source of 𝜔-3 oil, the viscosity and cohesion of ground chia is fairly low for food applications.15,30,31 There is a need for improvement in the functional performance of ground chia seeds. Ground chia seeds, containing 𝜔-3 oil, were used in combination with Nutrim, oat bran concentrate (OBC), and whole oat flour (WOF) containing 𝛽-glucan to produce chia–oat composites, described in a patent application by Inglett and Chen.30 The oat component appeared to be helpful in absorbing chia oil and improving physical properties. The physical properties of hydrothermal processed chia and oat bran concentrate hydrocolloids were evaluated in an earlier study.31 Also, pasting and rheological properties of ground chia seeds composited with oat products at 1:9, 1:4, and 1:1 ratios were previously investigated.32 These composites had improved water-holding capacities and showed interesting properties. However, chia–oat composites were not studied in food products. In this exploratory study, only the chia–oat composites (1:4) were used and evaluated. The objective of our study was to evaluate the physical properties of newly developed chia–oat composites along with their formulated dough and cookie products. The information could be valuable for developing new functional food products with desirable texture and health benefits.
MATERIALS AND METHODS Chia–oat composites development Black chia seeds (chia) were purchased from Chia Seed Growers (Cuernavaca, Mexico). Organic whole oat flour colloidal fine (WOF) was provided by Grain Millers (Eugene, OR, USA). Oat bran concentrate (OBC) was supplied by Quaker Oats, Chicago, IL, USA (Lot 18608408). Nutrim (Lot 35503475N170) was provided by VDF FutureCeuticals (Momence, IL, USA). Nutrim was prepared by steam jet cooking OBC, sieving, and drum drying.19 All-purpose wheat flour used in the study was produced by General Mills (MN, USA). Black chia seeds were ground for 40 s using a 1095 Knifetec mill (Foss Analytical AB, Sweden). Ground chia seeds were mixed with corresponding oat product using a N-50 Hobart mixer (Hobart Canada Inc., Ontario, Canada) for 1 min. The mixtures were ground again with a 1095 Knifetec mill for another 40 s for additional mixing to obtain the desired fine composites.
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Cookie preparation Cookies were prepared following AACC methods 10–52 for sugar cookie as described by Lee and Inglett, with modifications.33,34 Sugar (72 g; C&H Sugar Company, Crockett, CA, USA), brown sugar (22.5 g; C&H), non-fat dry milk (2.3 g; Carnation, Nestlé, Vevey, Switzerland), salt (2.8 g), and sodium bicarbonate (2.3 g; Arm & Hammer, Church & Dwight, Co., Inc., Princeton, NJ, USA) were mixed. The mixture was transferred on top of shortening (100 g, Crisco, JM Smucker Company, Orrville, OH, USA) and blended with a paddle beater in a mixing bowl using a KitchenAid mixer (St Joseph, MI, USA) at speed 2 for 3 min, scraping down every minute. Water (49.5 g) containing ammonium bicarbonate (1.1 g, Calumet, Kraft, Northfield, IL, USA) was added and mixed for 1 min at speed 1. After scraping down, the contents were mixed for another minute at speed 2. Flour or flour containing chia–oat composites were added while mixing at speed 1, and mixing was continued for 2 min at speed 2 with scraping every 30 s. Dough was flattened by using a rolling pin on an aluminum pan with 7 mm gauge strips, and cut with a cookie cutter of 6 cm diameter. Cookies were baked at 205 ∘ C in a convection oven (XAF-113 LineChef Stefania, Cadco Ltd, Winsted, CT, USA) for 10 min and cooled. The cookies were stored in a sealed plastic bag until measurements were taken. Water loss, moisture content and water activity Water losses during baking were measured by the weight of the difference before and after baking. After grinding three cookies with a pestle in a mortar, moisture content and water activity were measured. Moisture contents of cookies were determined by drying 5 g of sample at 105 ∘ C to a constant weight (about 3–4 h). The water activity was measured using an Aqua Lab water activity meter (Decagon Devices Inc., Pullman, WA, USA). Geometrical properties Six cookies were placed next to each other and the total diameter was measured. They were rotated by 90∘ and measured again. After repeating two more times, the average of four measurements was divided by six to calculate the average diameter of a cookie. To measure the height, six cookies were stacked, measured, restacked in a different order, and measured again. The average cookie height cookie was the mean of three readings divided by six. The spread ratio was calculated by dividing the diameter by the height. Nine measurements for each replicate were taken (n = 9). Color The color of the cookies was measured with a Hunter Lab spectrocolorimeter (Labscan XE, Hunter Associates Laboratory Inc., Reston, VA, USA). The colorimeter was calibrated using a standard white plate. The color values L*, a*, b* were measured with a C illuminant and a 10∘ standard observer. The dimension L* indicates lightness, with 100 for white and 0 for black; a* indicates redness when positive and greenness when negative; b* indicates yellowness when positive and blueness when negative. Texture analysis Cookie hardness was measured using recommended methods of TA-XT2 Texture Analyzer (Texture Technology Crop., Scarsdale, New York, USA) equipped with 30 kg load cell. The cookie hardness measurement was conducted by a cutting force using a
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Cookie flour formulations Cookie flour formulations were as follows: (i) wheat flour only (control); (ii) the wheat flour in cookies was replaced by 20% chia–Nutrim composites 1:4; (iii) the wheat flour in cookies was replaced by 20% chia–OBC composites 1:4; and (iv) the wheat flour in cookies was replaced by 20% of chia–WOF composites 1:4.
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www.soci.org three-point bending method with sharp-blade probe, 6 cm long and 1 mm thick. The hardness of the cookies was indicated by the maximum peak force required to break them. The slotted inserts were adjusted and secured on the heavy-duty platform to fit sample size and position centrally under the knife edge. The instrument was set to ‘return to start’ cycle, a pre-test speed of 1.5 mm s−1 , test speed of 2.0 mm s−1 , post-test speed of 10 mm s−1 , and a distance of 5.0 mm. Dough hardness was measured using a TA-XT2 Texture Analyzer equipped with 5 kg load cell in compression mode by penetrating with a flat probe of 5 mm diameter. The cookie dough (110 g) was evenly and gradually placed in a dough cell while compressing and flattening the surface with a plunger to avoid randomly distributed pockets of air as a potential cause of variability in consistency measurements. The test was conducted at a pre- and post-test speed of 2.00 mm s−1 and test speed of 3 mm s−1 , post-test speed of 10.0 mm s−1 , and distance of 20 mm. Water-holding capacity (WHC) WHCs were determined according to the procedure of Ade-Omowave et al., with minor modifications.35 A sample (2 g) was mixed with 25 g distilled water and vigorously mixed using a vortex stirrer for 1 min for a homogenous suspension and then held for 2 h, followed by centrifugation at 1590 × g for 10 min. Each treatment was replicated twice. WHC was calculated using the following equation: ) [ ] ( WHC g kg−1 = water added (g) − decanted water (g) ∕ dry sample weight (g) × 1000 Pasting properties The pasting properties of samples were evaluated using a Rapid Visco Analyzer (RVA-4, Perten Scientific, Springfield, IL, USA). Samples (2.24 g dry basis) were made up to a total weight of 28 g with distilled water in an RVA canister (80 g kg−1 solids, w/w). The viscosity of the suspensions was monitored during the following heating and cooling stages. The suspensions were equilibrated at 50 ∘ C for 1 min, heated to 95 ∘ C at a rate of 6.0 ∘ C min−1 , maintained at 95 ∘ C for 5 min, and cooled to 50 ∘ C at rate of 6.0 ∘ C min−1 , and held at 50 ∘ C for 2 min. For all test measurements, a paddle rotating speed (16.8 rad s−1 ) was maintained constant throughout the entire analysis, except for 96.3 rad s−1 for the first 10 s to disperse sample. Each sample was analyzed in duplicate. The results were expressed in Rapid Visco Analyzer units (RVU, 1 RVU = 12 cP).
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Rheological properties A sample was loaded on a 2 cm diameter X-hatch parallel stainless plate using a rheometer (AR 2000, TA Instruments, New Castle, DE, USA). The outer edge of the plate was sealed with a thin layer of mineral oil (Sigma Chemical Co., St Louis, MO, USA) to prevent dehydration during the test. All rheological measurements were carried out at 25 ∘ C using a water circulation system within ± 0.1 ∘ C. A strain sweep experiment was conducted initially to determine the limits of linear viscoelasticity; then a frequency sweep test was carried out to obtain storage modulus (G′ ) and loss modulus (G′′ ) at frequencies ranging from 0.1 to 10 rad s−1 . A strain of 0.5, which was within the linear viscoelastic range, was used for the dynamic experiments. All rheological measurements for samples were performed in duplicate.
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GE Inglett, D Chen, S Liu Statistical analysis Data were analyzed using SAS software (1999; SAS Institute, Rayleigh, NC, ISA) using analysis of variance with Tukey’s multiple comparison adjustment to determine significant differences (P < 0.05) between treatments.36
RESULTS AND DISCUSSION Water-holding capacity The WHC of the ground chia seeds and their composites with oat products are shown in Table 1. The WHC of chia–Nutrim 1:4 (6110 g kg−1 ) was the highest value among the samples tested, which can probably be attributed to the WHC of chia (4953 g kg−1 ) and Nutrim (5535 g kg−1 ). The WHC of chia–OBC composite (5063 g kg−1 ) was almost twice that of OBC alone (2668 g kg−1 ). The WHC of chia–WOF composite (2903 g kg−1 ) was about twice that of WOF (1330 g kg−1 , similar to the chia–OBC composite and OBC. The high WHC of chia could be attributed to the mucilage found in the outer layers of the chia seed coat.9 When chia seeds contact water, the mucilage appears as a transparent ‘capsule’ surrounding the seed. Chia seeds and their mucilage can be used as a thickener in foods.9 In addition, the WHC of chia could be partially attributed to its protein content, which has a good WHC (4.06 kg kg−1 ) along with an excellent oil retention capacity (4.04 kg kg−1 ).17 All the WHC of oat products (Nutrim, 5535 g kg−1 ; OBC, 2668 g kg−1 ; WOF, 1330 g kg−1 ) were higher than the WHC of wheat flour (753 g kg−1 ). The WHC trend of oat products appears to be related to their 𝛽-glucan contents (Nutrim, 150 g kg−1 ; OBC, 120 g kg−1 ; WOF, 40 g kg−1 ; wheat flour, 12 g kg−1 ), suggesting 𝛽-glucan content may have an important role in WHC. The actual WHCs of chia–oat composites were all slightly higher than the theoretical WHC of the two starting materials (Table 1). It appears that there are interactions between the two starting materials. The improved WHC makes chia–oat composites attractive ingredients for increasing water retention and moisture in bakery and other foods. Pasting properties of composites The pasting curves of the starting materials obtained by RVA are presented in Fig. 1. The Nutrim pasting curves (Fig. 1) exhibited a sharp increase in viscosities during the initial 10 min heating period just before the temperature reached 95 ∘ C, followed by a sharp decrease in viscosity during heating and cooling, showing a considerably lower final viscosity. It is known that the viscosity of completely gelatinized starch slurry decreases during heating.37 These characteristics are common for pre-gelatinized flour38 and
Table 1. WHC of starting materials and chia–oat composites Sample
WHC (g kg−1 )
Wheat flour Chia Nutrim Chia–Nutrim (1:4) OBC Chia–OBC (1:4) Whole oat flour Chia-WOF (1:4)
753 ± 11f 4953 ± 209c 5535 ± 49b 6110 ± 290a 2668 ± 88d 5063 ± 88bc 1330 ± 21e 2903 ± 11d
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
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Physical properties of sugar cookies containing chia–oat composites
Figure 1. Rapid Visco Analyzer pasting curves of starting materials of cookies.
Figure 2. Rapid Visco Analyzer pasting curves of wheat flour, chia, Nutrim and chia–Nutrim composite.
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Figure 3. Rapid Visco Analyzer pasting curves of wheat flour, chia, OBC, and chia–OBC composite.
Figure 4. Rapid Visco Analyzer pasting curves of wheat flour, chia, WOF, and chia–WOF composite.
reaching 95 ∘ C. This may be due to the lower viscosity of ground chia seeds during the initial increasing temperature phase. However, the final viscosity of chia–Nutrim 1:4 was higher than Nutrim, suggesting that it may be related to the higher final viscosity of ground chia seeds during cooling (Fig. 2). A similar trend for the pasting curve (Fig. 3) was observed for chia–OBC composites as for OBC, but chia–OBC composite had higher initial viscosity peak compared to OBC. The initial viscosity from chia–OBC and OBC increased beyond 95 ∘ C and during cooling, resulting in a similar high final peak near 222 RVU. Overall, chia–OBC 1:4 composites had higher final viscosities (Fig. 3, 221.7 RVU) than chia–Nutrim 1:4 (Fig. 2, 54.3 RVU), and chia–WOF composites (Fig. 4, 109.3 RVU). For the chia–WOF 1:4 composite (Fig. 4), viscosities increased gradually during heating. The first peaks were observed at 95 ∘ C followed by a shallow breakdown and final viscosity peak was reached during cooling. Although similar trends were observed for WOF compared with chia–WOF (1:4), the latter had an unexpectedly higher viscosity (109.3 RVU) compared to whole oat flour (77.3 RVU). This could be attributed to the excellent WHC of the chia composites. Moreover, it could be related to the interactions of fiber from both chia and the oat product. All these factors together could play an important role in the interactions, resulting in increasing viscosities.
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typical for Nutrim, since it had undergone hydro-thermal jet cooking in which starch gelatinization occurred. The viscosity of OBC (Fig. 1) increased gradually after heating until reaching 95 ∘ C, and increased continually during cooling, resulting in a considerably higher final viscosity. No dramatic breakdowns (peak viscosity minus the lowest point of viscosity after peak) were observed for OBC. This suggested that 𝛽-glucan in uncooked OBC after heating resulted in an entanglement of molecules during cooling, indicating the formation of a matrix with greater stability under heat and shear. The initial viscosity for WOF (Fig. 1) was increased until the temperature reached 95 ∘ C, showing a lower viscosity peak than Nutrim and OBC but higher than chia, and then slowly increased after a small breakdown similar to OBC. Slowly increasing viscosities of ground chia seeds (Fig. 1) were observed before the temperature reached 95 ∘ C, followed by a continuous increase, and resulting in a final peak that was similar to WOF. Wheat flour (Fig. 1) showed a small initial viscosity peak where the temperature reached 95 ∘ C; viscosities decreased gradually during heating and remained constant during cooling. Wheat flour had the lowest final peak among all the samples. The viscosity curve of chia–Nutrim 1:4 (Fig. 2) had similar patterns to the Nutrim curve (Fig. 2), but the viscosity of chia–Nutrim 1:4 was slightly lower than Nutrim at the initial peak before
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GE Inglett, D Chen, S Liu
Table 2. Geometry properties of cookies Diameter Before bake (mm) Control Chia-Nutrim Chia-WOF Chia-OBC
60 60 60 60
Thickness
After bake (mm)
Increase (mm)
Increase (%)
70.3 ± 0.5a 61.9 ± 0.8c 67.4 ± 0.8b 70.2 ± 0.0a
10.3 ± 0.5a 1.9 ± 0.8c 7.4 ± 0.8b 10.2 ± 0.0a
17.1 ± 0.8a 3.1 ± 0.8c 12.3 ± 0.8b 16.9 ± 0.0a
Before bake (mm) 7 7 7 7
After bake (mm)
Increase (mm)
Increase (%)
Spread ratio
11.8 ± 0.1b 12.0 ± 0. a 11.3 ± 0.2c 11.3 ± 0.2c
4.8 ± 0.1b 5.0 ±0.1a 4.3 ± 0.2c 4.3 ± 0.2c
67.9 ± 1.4b 72.0 ± 1.2a 60.7 ± 3.0c 61.9 ± 2.8c
5.95 ± 0. 21b 5.16 ± 0.25c 5.96 ± 0.26b 6.21± 0.11a
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Table 3. Color profile and water activity of cookies L* Control Chia–Nutrim Chia–WOF Chia–OBC
a*
49.07 ± 0.04a 49.79 ± 0.89a 47.12 ± 0.36b 47.67 ± 0.33b
b*
15.61 ± 0.05a 11.91 ± 0.21d 13.87 ± 0.13b 13.48 ± 0.05c
33.20 ± 0.08a 27.33 ± 0.45c 28.70 ± 0.35b 28.72 ± 0.03b
Water activity (aw ) 0.2400 ± 0.0014c 0.2835 ± 0.0007a 0.2485 ± 0.0007b 0.2060 ± 0.0014d
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Improvements in the textural properties of food using oat 𝛽-glucan hydrocolloids have been reported.39 The RVA data are not only useful for this cookie study but also provide useful information for food processing. Composites having low viscosity may be suitable for products such as nutritional bars. Composites with high initial paste viscosity suggest their uses in food formulations that require little heat during processing, such as beverages. Composites with high viscosities could be used in products such as breads and cookies for increased textural quality and health benefits. Geometrical properties of cookies Cookies containing chia–Nutrim composites had the smallest diameter (61.9 mm) after baking and significantly highest thickness after baking among all the cookies (Table 2). Cookies containing chia–OBC composite had a similar size (70.2 mm) to the control (70.3 mm), which contained wheat flour only. The diameter of the cookie containing chia–WOF composite (67.4 mm) was between the control (70.3 mm) and the cookie containing chia–Nutrim composite (61.9 mm). The spread ratio is the value of the diameter divided by thickness. Chia–OBC composites had the highest spread ratio (6.21). The spread ratio of cookies containing chia–Nutrim composite was the lowest (5.16) among the cookies. The lowest spread value may be related to the high WHC of chia–Nutrim, which had decreased spreading during baking.
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Color of cookies The colors of cookies after baking are shown in Table 3. Cookies containing chia–Nutrim (L* 49.79) and control (L* 49.07) were lighter in color compared with cookies containing chia–OBC (L* 47.67) and chia–WOF (L* 47.12), since the dimension L* indicates lightness, with 100 for white and 0 for black. The value a* indicates redness when positive and greenness when negative. All the cookies showed redness to different degrees. The a* value (15.61) of control cookies was the highest, indicating more redness, and cookies containing chia–Nutrim composite (11.91) revealed the
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least redness. Also, all the cookies showed yellowness to different degrees, since b* indicates yellowness when positive. Similar to the a* value, control cookies (b* 33.20) had the highest value for yellowness among the cookies. Water loss, moisture content of cookies and water activity Among all the cookies, those containing chia–Nutrim composites had the lowest water loss (10.4%) during baking, with the highest cookie moisture content (4.01%) after baking, perhaps because of the high WHC of chia–Nutrim composites. The results of water loss during baking and cookie moisture were consistent with WHCs of cookies (Tables 1 and 4). Water is an important aspect of food stability and shelf-life. The growth and metabolic activities of bacteria, molds, and yeasts are retarded and eventually inhibited as the water activity (aw ) of foods is decreased. Water activity of the cookies prepared with control and cookies containing 20% Nutrim, OBC and WOF were 0.24, 0.28, 0.25, and 0.21 (Table 3), respectively, which were lower than the limit of water activity for spoilage bacteria, yeasts and molds: approximately 0.90, 0.85–0.88, and 0.80, respectively; the rate of chemical reaction in food decreases much more slowly with reduced moisture content, and enzymatic activity in foods may be significant at water activities as low as 0.30.40 Texture of dough and cookies The texture valuations of dough and cookies are presented in Table 4. Dough hardness was tested by a penetrating force using a 5 mm diameter probe. Cookie dough containing chia–Nutrim had a high texture value (0.407 kg), followed by the control (0.344 kg) and cookies containing chia–WOF composites (0.332 kg), with cookies containing chia–OBC having the lowest value (0.298 kg). The highest dough hardness value from cookies containing chia–Nutrim composites may be related to its high WHC. A similar hardness trend was observed for cookies as well as cookie dough (Table 4). Cookies containing chia–Nutrim required the maximum cutting force (5.020 kg) to break the cookie. Again, this may be
Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
J Sci Food Agric 2014; 94: 3226–3233
Physical properties of sugar cookies containing chia–oat composites
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Table 4. Moisture, water loss during baking, and the texture of cookies and dough Water loss during baking (%) Control Chia–Nutrim Chia–WOF Chia–OBC
12.8 ± 0.3a 10.4 ± 0.8c 12.1 ± 0.4b 12.4 ± 0.3b
Cookie moisture (%) 2.33 ± 0.00b 4.01 ± 0.03a 2.38 ± 0.04b 2.02 ± 0.02c
Dough hardness Penetrating force (kg) 0.344 ± 0.024b 0.407 ± 0.009a 0.332 ±0.009cb 0.298 ±0.005c
Cookie hardness Cutting force (kg) 2.174 ± 0.006d 5.020 ± 0.052a 3.137 ± 0.000b 2.466 ± 0.013c
Means ± standard deviation; n = 3; means followed by the same letter within the same column are not significantly different (P > 0.05).
Figure 5. Dynamic viscoelastic properties of doughs containing chia–oat composites.
due to the high WHC of Nutrim, which resulted in the highest thickness among the cookies (Tables 1 and 2). In contrast, cookies containing chia–OBC composites required the least cutting force to break them. The least cutting force for the cookies containing chia–OBC composites may be related to the thickness (11.3 mm), which was lower among these cookies. Furthermore, the molecular weight for Nutrim at its peak was 3.0 × 105 , which was smaller than that of OBC (1.5 × 106 ), as measured by a size-exclusion chromatography instrument (Shiamdzu, VP series, Tokyo, Japan).41 The high molecular weight of OBC may also be related to cookie texture, which was easier to break down than cookies containing chia–Nutrim composites. The results of dough texture and cookies were in agreement with rheological data (Fig. 5).
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viscous properties.29 The highest values of storage G′ and loss G′′ moduli were observed for dough containing chia–Nutrim composites, followed by dough with chia–WOF, and then control and chia–OBC. The values of storage G′ and loss G′′ moduli for dough containing wheat flour only (control) and chia–OBC dough were almost identical; and both G′ and G′′ were considerably lower than the other two doughs. This indicated that there were insignificant differences on the rheological properties of control dough and dough containing chia–OBC composites. The dough containing chia–Nutrim composite had the most solid properties, followed by dough with chia–WOF composite, control dough, and dough containing chia–OBC composite. Furthermore, these rheological patterns of the chia–oat composites were clearly confirmed by the tan 𝛿 values (G′′ /G′ ) (Fig. 6) because the values of tan 𝛿 indicate the ratio of energy lost to the amount of energy stored during a test cycle. The phase shift 𝛿 is defined by 𝛿 = tan−1 (G′′ /G′ ), which indicates whether a material is solid (𝛿 = 0∘ ), liquid (𝛿 = 90∘ ), or between (0∘ < 𝛿 < 90∘ ). Therefore, the values of tan 𝛿 are from zero to infinity; tan 𝛿 = 1 means G′ = G′′ , tan 𝛿 < 1 represents G′ > G′′ , and tan 𝛿 >1 indicates G′ < G′′ . The tan 𝛿 value has been used to indicate the strong relationship between viscous behavior and the degree of casein hydrolysis.43 In general, the tan 𝛿 values for all doughs were the highest at the lowest frequency and decreased in frequency until it reached 1 rad s−1 . After that, all tan 𝛿 values increased slightly and converged in a tan 𝛿 range from 0.54 (control) to 0.47 (chia–Nutrim). These rheological data appeared to indicate that cookie dough containing chia–oat composites had similar elasticity and stability to the control. This property could provide better shape retention during handling and baking. Because the experimental conditions we adopted were similar to actual processing situations, all our
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Rheological properties of dough The dynamic viscoelastic properties of dough have been related to the quality of baked and other food products.29 G′ , an elastic (storage) modulus, represents the non-dissipative component of the mechanical properties of a material and reflects its elastic characteristics. On the other hand, the viscous (loss) modulus (G′′ ) characterizes the dissipative part of the mechanical properties and represents the viscous flow of the material. G′ and G′′ values against frequency for all the doughs tested are displayed in Fig. 5. Both moduli (G′ and G′′ ) of all samples were increased with increasing frequencies, showing frequency dependence, indicating that these materials could have elastic properties. 42 Moreover, the elastic modulus G′ was higher than the viscous modulus G′′ throughout the frequency range (Fig. 5) for all samples with different levels, suggesting that they had more elastic properties than
Figure 6. Values of tan 𝛿 versus frequency (rad s−1 ) for doughs containing chia–oat composites.
www.soci.org findings on rheological characteristics could be beneficial for processing and developing chia–oat composites for new food applications. The results of the geometry properties of cookies, and the texture of dough and cookies, indicated that cookies formulated with chia–WOF and chia–OBC composites are closer to control values (Tables 2 and 4). It is suggested that chia–WOF and chia–OBC are suitable for bakery products, whereas chia–Nutrim composite could probably be used for beverages and dressings since it has high WHC and high initial viscosity (Fig. 2). The incorporation of chia (Salvia hispanica L.) seeds into baked food products, muffins and cookies has been reported, but the study did not involve oat products. 44 In addition, there are many cookie recipes using whole chia and oatmeal. However, they were not scientifically studied and reported.
CONCLUSIONS The physical properties of chia–oat composites and their use in cookies provide useful information for their potential functional food applications. Chia–oat composites have unique qualities because they provide the oat-soluble fiber 𝛽-glucan, which is beneficial for food texture and for coronary heart disease prevention along with the health benefits of the 𝜔-3 PUFA components of chia. The chia–oat composites are more easily utilized by the human body compared to the whole chia seeds on the market. Chia seeds alone are not easily utilized as food ingredients because of their high oil content and low cohesiveness. Chia–oat composites were created using a feasible dry blending procedure which could maintain the original oat quality along with the lipoidal character and components of the chia. Besides the nutritional aspects of the chia–oat composites, these composites have improved WHC and texture, and useful viscoelastic qualities. Also, our results indicated that the replacement of wheat flour by chia–WOF and chia–OBC composites would not affect the textural quality of cookies. Although chia–oat composites showed differential pasting properties compared with wheat flour, the rheological properties of cookie doughs containing chia–oat composites exhibited similar elastic and stability properties. Chia–Nutrim composites with their excellent WHC may be more suitable for food products, such as cakes. These chia–oat products could have applications for various cookies and other bakery products having improved nutritional value and desirable textural qualities for health-concerned consumers.
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