Effect of partial replacement of wheat flour with varying levels of flaxseed flour on physicochemical, antioxidant and sensory characteristics of cookies

Effect of partial replacement of wheat flour with varying levels of flaxseed flour on physicochemical, antioxidant and sensory characteristics of cookies

Bioactive Carbohydrates and Dietary Fibre 9 (2017) 14–20 Contents lists available at ScienceDirect Bioactive Carbohydrates and Dietary Fibre journal...

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Bioactive Carbohydrates and Dietary Fibre 9 (2017) 14–20

Contents lists available at ScienceDirect

Bioactive Carbohydrates and Dietary Fibre journal homepage: www.elsevier.com/locate/bcdf

Effect of partial replacement of wheat flour with varying levels of flaxseed flour on physicochemical, antioxidant and sensory characteristics of cookies

MARK



Maninder Kaur , Varinder Singh, Rajwinder Kaur Department of Food Science and Technology, Guru Nanak Dev University, Amritsar 143005, India

A R T I C L E I N F O

A BS T RAC T

Keywords: Flaxseed Cookies Carbohydrate Antioxidant Sensory Physical

Replacement of wheat flour with varying levels of flaxseed flour (0–30%) on nutritional, functional and antioxidant properties of cookies was investigated. Cookies produced from composite flour mixes were significantly (p < 0.05) higher in protein, fat, ash and fiber contents than the control. Flaxseed was found to be rich in antioxidant potential as evident from the higher total phenolic content, free radical scavenging activity and reducing power of composite flour cookies in comparison to control. The results indicated that as the concentration of flaxseed flour in the blend increased, the cookies became darker in color with a significant (p < 0.05) increase in their spread factor. Sensory panellists rated cookies containing 15% level of flaxseed flour as highly acceptable in relation to their overall acceptability scores. Beyond this level of replacement the texture and flavour of cookies was adversely affected. Principal component analysis revealed that physicochemical and sensory properties of cookies produced by 10% replacement with flaxseed flour were closest to the control cookies.

1. Introduction Flaxseed (Linum usitatissimum L.) also known as linseed, is enjoying an upsurge in popularity as a result of reports on its health benefits to human and its potential to reduce the risk of certain diseases (Oomah & Mazza, 2000). The seed is oval and flat with a pointed tip and has a smooth glossy surface. It differs in dark brown to yellow in color according to its different varieties (Freeman, 1995). Flaxseed has a pleasant nutty taste with crisp and chewy texture (Carter, 1996). Although, flaxseed is an oilseed crop, but proximate composition of flaxseed makes it more beneficial for its utilization in various food products as a functional food ingredient. Flaxseed contains approximately 38–45% oil, 28% dietary fiber, and 21% protein (Daun, Barthet, Chornick, & Duguid, 2003). The functional components in flaxseed that provide health benefits include α-linolenic acid, lignans and dietary fiber (Hall, Tulbek, & Xu, 2006). Antioxidant activity of lignans may contribute to the anticancer activity of flaxseed (Kangas, Saarinen, & Mutanen, 2002; Prasad, 1997; Yuan, Rickard, & Thompson, 1999). Flaxseed is a rich source of different types of phenolic compounds such as phenolic acids, flavonoids, phenylpropanoids and tannins (Kasote, 2013). The behavior of proteins in a food system is affected by their techno-functional properties which are mainly dependent on structure of the protein, their hydration mechanisms for solubility and water or



oil retention capacity, rheological characteristics for viscosity and gelation, and their interfacial properties for emulsions and foams (Moure, Sineiro, Dominguez, & Parajo, 2006). The physico-chemical parameters such as temperature, pH, ionic strength and particle size have influence on the techno-functional properties (Dev & Quensel, 1986; Oomah, Kenaschuk & Mazza, 1995; Krause, Schultz, & Dudek, 2002; Martinez-Flores, Barrera, Garnica-Romo, Penagos, Saavedra & Macazaga-Alvarez, 2006). Flaxseed proteins have real potential for use as techno functional food ingredient in several food products particularly in breads, meat emulsions, and sauces. According to Oomah and Mazza (1998), compositional changes which occur during processing of flaxseed are to be kept in mind when adding value to flaxseed products. Rabetafika, Remoortel, Danthine, Paquot, and Blecker (2011) reported the comparison of functional properties of flaxseed proteins to those of other oilseed proteins. Rathi and Mogra (2013) studied the acceptability of biscuit making quality of flaxseed flour and found that the acceptable level of flaxseed flour in biscuit was 20–40% addition to wheat flour. Rajiv, Indrani, Prabhasankar, and Rao (2011) studied the effect of replacement of roasted and ground flaxseed (RGF) at 5–20% level on the wheat flour dough. The baking test of cookies showed a marginal decrease in spread ratio but beyond replacement of 15% RGF the texture and flavour of the cookies was adversely affected. Khouryieh and Aramouni (2012) investigated the physical and sensory characteristics of cookies prepared from varying levels of replacement of flaxseed

Corresponding author. E-mail address: [email protected]ffmail.com (M. Kaur).

http://dx.doi.org/10.1016/j.bcdf.2016.12.002 Received 10 August 2016; Received in revised form 12 November 2016; Accepted 19 December 2016 2212-6198/ © 2016 Elsevier Ltd. All rights reserved.

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flour (0–18%) with wheat flour. Alpaslan and Hayta (2006) suggested that flaxseed flour could be added to a typical snack formulation up to levels of 10% with a reasonable acceptance offering promising nutritious and healthy alternative to consumers. Though there have been previous reports on physical and sensory characteristics of flaxseed fortified cookies, but there has been a scarcity of reports on antioxidant potential of flaxseed and how much level is enhanced and losses which occur upon baking of flaxseed incorporated cookies. This prompted us to undertake the present investigation with the objective to evaluate the physical, chemical, sensory, and antioxidant characteristics of cookies containing various levels of flaxseed flour. Accordingly a level of flaxseed flour substitution to wheat flour was suggested with reasonable acceptable sensory scores and superior nutritive value and antioxidant potential than wheat flour cookies.

2.6. Antioxidant properties The antioxidant properties of flours, composite flour mixes and cookies prepared from them were estimated as follows: 2.6.1. Total phenolic content (TPC) TPC of different samples was determined according the Folin– Ciocalteu spectrophotometric method (Sharma & Gujral, 2011). Sample (200 mg) was extracted at room temperature (25 °C) with 4 ml of acidified methanol (HCl/methanol/water, 1:80:10, v/v/v) for 2 h. An aliquot of extract (200 μl) was added to 1.5 ml freshly diluted (10 fold) Folin–Ciocalteu reagent. After equilibration for 5 min, the extract was then mixed with 1.5 ml of sodium carbonate solution (60 g/ l). It was then incubated at room temperature (25 °C) for 90 min, and the absorbance of the mixture was read at 725 nm (Shimadzu, UV1800, Japan). Acidified methanol was used as a blank. The results were expressed as μg of gallic acid equivalents (GAE) per gram of sample.

2. Materials and methods 2.1. Materials

2.6.2. Antioxidant activity (AOA) AOA was measured by modified method of Brand-Williams, Cuvelier, and Berset (1995). Samples (100 mg) were ground and extracted with 1 ml methanol for 2 h and centrifuged at 3000g for 10 min. The supernatant (100 μl) was separated and reacted with 3.9 ml of 6×10−5 mol/l of 2,2-diphenyl-1-picrylhydrazyl (DPPH) solution. Absorbance of the extract (A) at 515 nm was read at 0 and 30 min using methanol as blank. Antioxidant activity was calculated as % discolouration. % Antioxidant activity =(1−(A of sample t=30 / A of control t=0)) ×100.

Flax seeds and wheat flour were procured from the local market of Amritsar, Punjab, India. The seeds were ground in a laboratory grinder and the flour so obtained was stored in an air tight container till further used. All the chemicals and reagents used were of analytical grade. 2.2. Composite flour mixes Besides the control sample (100% wheat flour), various blends of composite flour mixes (95WF:05FF, 90WF:10FF, 85WF:15FF, 80WF:20FF, 75WF:25FF and 70WF:30FF) were formulated and stored in air tight containers.

2.6.3. Reducing power The reducing power of sample was measured as described by Zhao et al. (2008). Sample (0.5g) was extracted with 80% methanol (0.5 ml) on metabolic shaker for 2 h. To the extract (1 ml) was added 2.5 ml potassium ferricyanide (1%) and phosphate buffer (2.5 ml, 0.2 mol/l, and pH 6.6) followed by incubation at 50 °C. Trichloroacetic acid solution (10%) was then added to the mixture, and then centrifuged at 10,000g for 10 min. The upper layer of solution (2.5 ml) was mixed with 0.5 ml ferric chloride (0.1%) and 2.5 ml deionized water. The absorbance of the mixture was measured at 700 nm. A standard curve was prepared using various concentration of ascorbic acid and the results were reported as μmol ascorbic acid equivalents/g of sample. Increased absorbance of the mixture indicated increased reducing power.

2.3. Preparation of cookies Cookies were prepared from both the control sample and composite flour mixes using AACC method (1995). Formula adopted was shortening 32 g, sugar 70 g, salt 1 g, sodium bicarbonate 1.25 g, dextrose solution (8.9 dextrose in 150 ml distilled water) 16.5 g, distilled water 8 g and flour 112.5 g. Dough was prepared in pin mixture (Morse ED series, USA) and flattened into a sheet of 0.5 cm thickness. It was then cut with the help of a cookie cutter into circular discs of diameter 4.5 cm and transferred to a lightly greased baking tray. Cookies were baked at 200 °C for 11 min in a reel oven (National Mfg. Co. Lincoln, USA). 2.4. Proximate composition

2.7. Physical properties of cookies

The samples of flours and cookies were estimated for their moisture, ash, fat, crude fiber and protein (N×6.25) content by employing the standard methods of analysis (AOAC, 1990).

2.7.1. Thickness After baking, the cookies were allowed to cool for 30 min. Five cookies were stacked one upon another on a flat surface and the stack height was measured with the help of vernier calliper. The cookies were restacked and remeasured to get the average thickness in cm. Readings were taken to nearest ½ cm.

2.5. Functional properties The flours from both flaxseed and wheat were analysed for various functional properties. For the determination of bulk density, method given by Kaur and Singh (2005) was adopted. Color measurements of flours and cookies were carried out using Hunter colorimeter Model D 25 optical Sensor (Hunter Associates Laboratory Inc., Reston, VA., U.S.A) on the basis of L*, a* and b* values. Water and oil absorption capacity of the flours was measured by centrifugation method of Sosulski (1962) and Lin, Humbert, and Sosulski (1974), respectively. Least gelation concentration was determined by the method of Coffmann and Garcia (1977). The emulsifying activity and stability were determined by the method of Yasumatsu et al. (1972).

2.7.2. Diameter Cookies were laid edge to edge and were measured for diameter. The cookies were rotated through 90 °C and were remeasured for width (cm). Readings were taken to the nearest ½ cm. 2.7.3. Spread factor The spread factor was obtained by finding the ratio between the average width and thickness of the cookies. It gave an indicator of cookie quality. 15

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the crude fiber content of full fat non roasted flaxseed flour to be 8.02% whereas Salehifar and Shahedi (2007) found the crude fiber content of wheat flour within the range of 0.12–1.89%. Flaxseed flour was significantly (p < 0.05) different from wheat flour in exhibiting higher fat, ash, protein and fiber contents (Table 1).

2.8. Sensory evaluation of cookies A taste panel performed sensory analysis of cookies formulated from control and composite flour blends. The cookies were evaluated for their color, appearance, texture, flavour and overall acceptability by a sensory panel of fifteen judges (10 female and 5 male, of age 20–38 yrs) using 9 point hedonic scale. Before the sensory evaluation was conducted the panels were trained by using commercial cookies to get familiar with the use of rating method, terminology for each attribute and sensory characteristics of cookies.

3.2. Functional properties of flours The data regarding the functional properties of the flours is reported in Table 1. Bulk density of FF and WF was found to be 0.58 g/ml and 0.63 g/ml, respectively (Table 1). Hussain et al. (2008) reported bulk density of full fat non roasted flaxseed flour to be 0.78 g/ ml. Water and oil absorption capacity of the two flours are represented in Table 1. Both water absorption (WAC) and oil absorption capacity (OAC) of FF was significantly (p < 0.05) lower than WF. Hussain et al. (2008) reported that WAC and OAC of full fat non roasted flaxseed flour to be 1.48 g/g. and 1.20 g/g, respectively. The water holding capacity (%) of coarse fraction and middle fraction of wheat flour was in the range of 50–68% (Blanchard, Labouré, Verel, & Champion, 2012). Protonotarious, Drakos, Evagelious, Ritzoulis, and Mandala (2014) observed the oil holding capacity of wheat flour in the range between 78.0–99.1%. Different structures of protein and the presence of different hydrophilic carbohydrates might be responsible for variations in the WAC of the flours (Oshodi & Ekperigin, 1989). Flours from flaxseed and wheat differed significantly in their abilities to emulsify oil. Emulsifying activity (EA) is defined as the ability of the flour to emulsify oil (Kaur & Singh, 2005). The value of EA for FF and WF was observed to be 85.3% and 20.4% respectively. Though FF showed higher EA, but the emulsions produced by it were less stable as evident from its lower emulsion stability (51.2%) in comparison to WF (88.7%). The EA of wheat flour in present study was higher than reported earlier by Shad et al. (2013). The gelation capacity of FF and WF did not differ significantly (p < 0.05) from each other. Flours contain high protein and starch contents and the gelation capacity of flours is influenced by a physical competition for water between protein gelation and starch gelatinization (Singh, 2001). The color characteristics of WF and FF were determined and the results showed that FF was much darker than WF as evident from its lower L* value. The value of a* and b* for FF were greater than those for WF indicating more reddish and yellow tinge in FF. Protonotariou et al. (2014) reported value of L, a* and b* for WF to be 88.6, −1.91 and 12.18 respectively.

2.9. Statistical analysis The data reported in all the tables are an average of triplicate observations unless otherwise specified. The data were subjected to statistical analyses using Microsoft Excel. A principal component analysis of cookie properties was carried out to provide differences and similarities among various composite flour blends using Minitab statistical software (Minitab Inc, State College, PA, USA). 3. Results and discussion 3.1. Proximate composition of flours Proximate composition of whole wheat flour (WF) and flaxseed flour (FF) is reported in Table 1. Moisture content is an important quality factor for the preservation, convenience in packaging and transport. In addition to it, moisture content also constitutes an identity standard (Bradely, 2003). Moisture and fat contents of WF and FF were found to be 12.15% and 2.33% and 6.5% and 40.44%, respectively. Fat content of Canadian flax was observed to be 41% (Morris, 2003). Hadnadev, Torbica, and Hadnadev (2011) found the fat content of wheat flours within the range of 0.75–2.34%. Ash content of FF and WF was 3.52% and 1.03%. which was in close agreement with previously reported value of 3.46% in full fat flax seed flour (Hussain, Anjum, Butt, Khan, & Asghar, 2006) and 0.47–1.14% in wheat flour (Hadnadev et al., 2011). Protein content of FF and WF was observed to be 20.12% and 11.52%, respectively. These values correlated well with the earlier reported values of 11.30% in wheat flour (Hussain et al., 2006) and 10.5–31% in flaxseed (Oomah & Mazza, 1993). Crude fiber content in FF and WF was found to be 8.05% and 0.59%, respectively. Hussain, Anjum, Butt, and Sheikh (2008) reported

3.3. Antioxidant properties of flours

Table 1 Proximate composition, functional properties, color characteristics and antioxidant activity of flaxseed and wheat flours. Parameters

Flaxseed flour

Wheat flour

Fat (%) Ash (%) Protein (%) Fiber (%) Bulk density (g/ml) WAC (g/g) OAC (g/g) EA (%) ES (%) LGC (%) L a* b* Total Phenolic content (mgGAE/100 g) Free radical scavenging activity (%) Reducing power (µmol AAE/g)

40.4 ± 0.03b 3.52 ± 0.12b 20.12 ± 0.05b 8.05 ± 0.14b 0.58 ± 0.23a 1.50 ± 0.12a 1.28 ± 0.09a 85.3 ± 0.09b 51.2 ± 0.07a 10.00a 59.1 ± 1.56a 6.06 ± 0.04b 14.3 ± 0.13b 91.8 ± 0.24b 48.24 ± 0.11b 24.57 ± 0.02b

2.3 ± 0.04a 1.03 ± 0.05a 11.52 ± 0.06a 0.59 ± 0.23a 0.63 ± 0.14b 2.68 ± 0.20b 2.36 ± 0.04b 20.4 ± 0.02a 88.7 ± 0.03b 10.00a 84.2 ± 0.23b 0.51 ± 0.01a 6.94 ± 0.42a 8.23 ± 0.18a 6.35 ± 0.13a 4.29 ± 0.01a

Results of total phenolic content (TPC) of the flours are represented in Table 1. The value of TPC for FF was much higher (91.8 mg GAE/ 100 g) as compared to WF (8.23 mg GAE/100 g). Adom, Sorrells, and Liu (2003) reported TPC for different wheat varieties within the range of 710–860 μmol gallic acid/g. Dharshini, Sumayaa, and Thirunalasundari (2013) found the total phenolic and tannin content of flaxseed flour to be 47.0 mg GAE/100 g. Flaxseed has been reported to contain 8–10 g/kg total phenolic acids (Oomah, Kenaschuk & Mazza, 1995). The antioxidant activity (AOA) of FF as determined by DPPH was significantly higher (48.24%) in comparison to WF (6.35%) (Table 1). According to Anwar and Przybylski (2012), the free radical scavenging activity of flaxseed flour using DPPH was observed to be 42.2% which was in close agreement with the values of flaxseed observed in the present study. The total antioxidant activity of wheat varieties ranged from 36.9 to 51.2μmol of Vitamin C equiv/100 g flour (Adom et al., 2003). The reducing power is also an indicator of antioxidant activity. The value of reducing power for FF and WF was evaluated as 24.57(µmol AAE/g) and 4.29 (µmol AAE/g), respectively. There is a direct relation between absorbance and reducing power. Higher the absorption, higher the value of reducing power of the sample. Gujral, Sharma, Gill, and Kaur (2013) reported the reducing power of wheat flour to be 7.7 μmol AAE/g.

Values are an average of triplicate observations; ± standard deviation; Values followed by similar superscript in a row do not differ significantly (P < 0.5). WAC - Water absorption capacity; OAC – Oil absorption capacity; EA – Emulsifying activity; ES – Emulsion stability; LGC – Least gelation concentration

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Table 2 Proximate composition of composite flour mixes. Parameters (%)

(WF 95%+FF 5%)

(WF 90% + FF 10%)

(WF 85% +FF 15%)

(WF 80%+ FF 20%)

(WF 75%+ FF 25%)

(WF 70%+FF 30%)

Moisture Fat Ash Protein Fiber

8.18 ± 0.20b 3.60 ± 0.19a 1.30 ± 0.02a 13.60 ± 0.01a 1.13 ± 0.07a

7.75 ± 0.04ab 6.08 ± 0.04b 1.33 ± 0.03a 14.53 ± 0.03ab 1.43 ± 0.03ab

7.57 ± 0.07ab 8.02 ± 0.03bc 1.45 ± 0.01ab 15.14 ± 0.03ab 1.68 ± 0.03ab

7.52 ± 0.07ab 9.58 ± 0.36c 1.54 ± 0.05ab 15.67 ± 0.02ab 1.91 ± 0.06b

7.31 ± 0.06a 11.63 ± 0.07 cd 1.65 ± 0.06b 17.07 ± 0.04b 2.08 ± 0.04b

7.16 ± 0.2a 13.56 ± 0.01d 1.73 ± 0.03b 17.24 ± 0.01b 2.22 ± 0.03c

Values are an average of triplicate observations; ± standard deviation; Values followed by similar superscript in a row do not differ significantly (P < 0.5). WF- wheat flour; FF- flaxseed flour

Table 3 Proximate composition, color characteristics and physical parameters of cookies prepared from blends of flaxseed and wheat flour. Parameters Moisture (%) Fat (%) Ash (%) Protein (%) Fiber (%) L a* b* Diameter (cm) Thickness (cm) Spread factor

(WF 100%) c

4.95 ± 0.13 13.54 ± 0.04a 1.24 ± 0.07a 7.40 ± 0.1a 0.42 ± 0.004a 61.66 ± 0.87c 9.96 ± 0.21b 26.33 ± 0.43b 5.14 ± 0.3a 0.71 ± 0.1a 7.23b

(WF 95%+5% FF) bc

4.34 ± 0.2 18.49 ± 0.06b 1.29 ± 0.05a 7.70 ± 0.3ab 0.5 ± 0.003a 57.59 ± 2.04b 7.21 ± 0.07a 25.19 ± 0.65ab 5.54 ± 0.1ab 0.85 ± 0.2b 6.51a

(WF 90%+10% FF) b

4.18 ± 0.07 19.26 ± 0.04b 1.35 ± 0.06ab 8.14 ± 0.1b 0.63 ± 0.01b 56.71 ± 0.3b 7.74 ± 0.54a 23.37 ± 0.97a 5.53 ± 0.2ab 0.83 ± 0.15b 6.66a

(WF 85%+15% FF) b

3.93 ± 0.02 20.4 ± 0.07bc 1.47 ± 0.07b 8.84 ± 0.2bc 0.84 ± 0.04bc 53.78 ± 0.25ab 8.55 ± 0.31ab 25.13 ± 0.33ab 5.56 ± 0.1ab 0.84 ± 0.2b 6.61a

(WF 80%+20% FF) ab

3.69 ± 0.05 21.02 ± 0.03bc 1.56 ± 0.1bc 9.01 ± 0.2bc 0.91 ± 0.03bc 53.43 ± 0.09ab 8.55 ± 0.07ab 25.13 ± 0.34ab 5.86 ± 0.2b 0.85 ± 0.3b 6.89ab

(WF 75%+25% FF) ab

3.53 ± 0.02 21.87 ± 0.06c 1.63 ± 0.04bc 9.28 ± 0.3c 1.12 ± 0.5c 53.43 ± 0.56ab 7.79 ± 0.09a 24.07 ± 0.24ab 5.86 ± 0.2b 0.84 ± 0.2b 6.97ab

(WF 70%+30% FF) 2.92 ± 0.14a 22.5 ± 0.01c 1.71 ± 0.05c 9.54 ± 0.4c 1.42 ± 0.02d 50.43 ± 0.57a 8.11 ± 0.34ab 23.57 ± 0.56a 5.88 ± 0.1b 0.83 ± 0.15b 7.08b

Values are an average of triplicate observations; n=3( ± Standard Deviation); Values followed by similar superscript in a row do not differ significantly (P < 0.5). FF – Flaxseed flour; WF – Wheat flour

increased from 5% to 30% in flour mixes, a significant (p < 0.05) decrease in moisture content was observed. Fat, ash, protein and fiber content of composite flour mixes increased as the concentration of FF increased progressively in the flour mixes (Table 2). The cookies prepared from different blends of FF and WF was also analysed for their chemical composition. FF had a significant (p < 0.05) effect on moisture content of the cookies relative to the control with a decrease in moisture content from 4.95% to 2.92% with the increase in concentration of FF to the blend (Table 3). In an earlier study it was observed that as the FF concentration increased in the blend, the moisture content of cookies decreased (Khouryieh & Aramouni, 2012). Due to low moisture content of the cookies, they were not susceptible to any microbial or chemical activities. There was a progressive increase in the fat, ash, protein, fiber content of cookies as the concentration of FF increased in the blend. Thus FF cookies were found to be nutritionally superior to 100% WF cookies at different levels of replacement. 3.4.2. Color characteristics of cookies The data regarding color characteristics of the cookies from different flour mixes are given in Table 3 and shown in Fig. 1. It was observed that as the concentration of FF in the blend increased, the cookies became darker in color as evident from lower L (61.66) value of the blends in comparison to control cookies. The highest value of L* was for control sample (61.66) and the lowest value (50.43) was for 30% flaxseed cookies. The value of a* and b* of FF incorporated cookies were less than a* and b* value of control cookies at different levels of replacement.

Fig. 1. Cookies prepared from different levels (5–30%) of incorporation of flaxseed flour to wheat flour.

3.4.3. Physical parameters of cookies Spread factor of cookies has long been used to determine the quality of flour for producing cookies (Gaines, 1990). Spread factor is the ratio that depends on the values of the thickness and diameter of the cookies. Highest spread factor was observed in control sample. With the increase in concentration of FF, spread factor of cookies increased

3.4. Physicochemical properties of cookies 3.4.1. Proximate composition of composite flour mixes and cookies Different composite flour mixes were analysed for their chemical composition (Table 2). The results showed that as the amount of FF 17

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Table 4 Total phenolic content (TPC), free radical scavenging activity (DPPH) and reducing power of composite flour mixes and cookies prepared from blends of flaxseed and wheat flour. Parameters

(WF 100%)

(WF 95%+5% FF)

TPC (mg GAE/100 g) Flour mixes 8.23 ± 0.23a 12.05 ± 0.12ab Cookies 6.56 ± 0.15a 8.96 ± 0.24ab DPPH (%) Flour mixes 6.35 ± 0.4a 8.24 ± 0.8ab Cookies 5.5 ± 0.7a 7.93 ± 0.3ab Reducing power (µmol AAE/g) Flour mixes 4.29 ± 0.02a 5.00 ± 0.01a Cookies 1.86 ± 0.01a 2.14 ± 0.03a

(WF 90%+10% FF)

(WF 85%+15% FF)

(WF 80%+20% FF)

(WF 75%+25% FF)

(WF 70%+30% FF)

14.57 ± 0.24b 9.82 ± 0.19ab

17.76 ± 0.13bc 12.16 ± 0.21b

19.08 ± 0.15bc 14.07 ± 0.14bc

21.28 ± 0.16bc 18.46 ± 0.25c

22.18 ± 0.18c 19.32 ± 0.22c

8.59 ± 0.3ab 8.13 ± 0.5b

9.36 ± 0.5b 9.05 ± 0.8b

10.32 ± 0.2bc 10.14 ± 0.3bc

11.16 ± 0.7bc 11.03 ± 0.9bc

12.54 ± 0.3c 12.25 ± 0.2c

6.43 ± 0.03ab 3.57 ± 0.03b

6.43 ± 0.02ab 3.57 ± 0.02b

7.86 ± 0.04ab 5.00 ± 0.03bc

7.86 ± 0.03ab 5.00 ± 0.01bc

9.29 ± 0.02b 6.43 ± 0.02c

Values are an average of triplicate observations; n=3( ± Standard Deviation); Values followed by similar superscript in a row do not differ significantly (P < 0.5). FF – Flaxseed flour; WF – Whole wheat flour; TPC – Total phenolic content; DPPH – (1,1- Diphenyl 2 picrylhydrazyl)

from 6.51 to 7.08 but was lower than control sample (7.23). Bala, Gul, and Riar (2015) reported the spread factor of WF cookies to be 7.26. Both diameter and thickness of cookies increased as the concentration of FF increased from 0% to 30% in the blend. FF cookies had higher thickness than the control sample.

Table 5 Sensory evaluation scores of cookies prepared from blends of flaxseed and wheat flour. Sample (WF (WF (WF (WF (WF (WF (WF

3.4.4. Antioxidant activity of flour mixes and cookies The antioxidant properties of composite flour mixes and cookies prepared from them are shown in Table 4. TPC of flour mixes increased with increase in concentration of FF in the blend. Upon baking a substantial decrease in TPC of cookies in comparison to flour mixes was observed. This decrease may be attributed to the loss of phenolic components during baking (Jonsson, 1991). Highest decrease in TPC was observed in blend containing 10% FF which showed 32.60% loss of TPC upon baking and lowest was recorded for blend containing 30% FF which showed 12.89% loss of TPC. Free radical scavenging activity of flour mixes also increased with an increase in level of FF to WF in the blends. Highest DPPH activity was exhibited by flour mixes containing 30% FF (12.54%). Cookies prepared from composite flour mixes showed a decrease in their DPPH activity upon baking. Highest decrease in DPPH activity was exhibited by control sample (13.36%) and lowest (1.16%) was shown by blend containing 25% level of FF upon baking. This may be due more effect of baking on the antioxidant activity of WF as compared to FF. Reducing power (RP) also followed a similar trend to TPC and free radical scavenging activity (Table 4). Different flour mixes showed higher RP values than cookies prepared from it. A significant increase in RP with an increase in level of FF to the blend was observed. The reducing power of an antioxidant compound is associated with the presence of reductones and their antioxidant capacity is based on the breaking of the free radical chain reaction by donating a hydrogen atom, and preventing peroxide formation (Sharma & Gujral, 2011). A significant reduction in RP upon baking with higher loss in control sample than composite flour mixes cookies was observed.

100%) 95% + 90% + 85% + 80% + 75% + 70% +

5% FF) 10% FF) 15% FF) 20% FF) 25% FF) 30% FF)

Color

Flavour

Texture

Overall acceptability

7.62 7.45 7.72 7.63 7.36 7.36 7.63

7.45 7.36 7.45 7.72 7.09 7.09 6.81

7.33 7.36 7.45 7.63 7.62 7.54 7.09

7.46 7.39 7.54 7.66 7.39 7.33 7.51

N – Number of panellists (15); values are means of 15 observations; FF- Flaxseed flour; WF – Wheat flour

prepared from 25% and 30% were given lowest scores with respect to overall acceptability. The results of the sensory evaluation of the biscuits prepared from the different treatments of the composite flour are according to the findings of Gambus, Mikulec, and Matusz (2003) who reported increasing the level of flaxseed flour, matri flour, and cowpea flour in the biscuits resulted in the significant decrease in the sensory attributes of the cookies. In a study reported by Khouryieh and Aramouni (2012) it was observed that flaxseed flour can be incorporated in cookies as a partial replacement up to 12% of wheat flour without negatively affecting the physical and sensory quality. 3.4.5.1. Principal component analysis. The results of principal component analysis of various physical, chemical and antioxidant properties of cookies prepared from composite flour blends and wheat flour are shown in Fig. 2a. The first and second principal component described 75.6% and 17.7% of the variances, respectively. Together the first two principal components represented 93.3% of the total variability. The loading plot of the two principal components provided information about several correlations between measured properties (Fig. 2a). A negative correlation of lightness with fat (r =−0.964), ash (r =−0.938), protein (r =−0.962), and fiber (r =−0.925) highly significant at p < 0.01 was observed. Cookie diameter was positively correlated to fat, ash, protein and fiber but negatively correlated to lightness at significance level of p < 0.01. TPC, AOA and RP showed a significant (p < 0.01) positive correlation with diameter, fat, ash, protein and fiber and a negative with lightness. Highly significant interrelationships between antioxidant parameters were observed. TPC was positively correlated with AOA (r =0.970, p < 0.01) and RP (r =0.941 p < 0.01) whereas AOA showed a significant positive correlation with RP (r =0.949, p < 0.01).

3.4.5. Sensory evaluation of cookies The direct and ultimate method for accessing the acceptability of cookies is by sensory evaluation. Sensory evaluation methods are more effective, require small sample size, less time and do not require trained panelist (Miskelly & Moss, 1985). The descriptive sensory evaluation values of cookies prepared from control and composite flour mixes are presented in Table 5. The sensory panellists rated control sample with highest score for color and flavour. These were closely followed by blend containing 15% FF. Highest overall acceptability scores (7.66) were for 15% flaxseed cookies and after this level of substitution a decrease in acceptability scores was observed. Hussain et al. (2006) prepared cookies by addition of flaxseed flour in wheat flour. These workers observed that maximum score was obtained by cookies prepared from whole wheat flour while minimum scores were given to cookies prepared from 25% and 30% flaxseed flour addition. Cookies

The sensory evaluation scores of the cookies were also subjected to PCA. The score plot (Fig. 2b) showed that control sample and cookies prepared from 10% and 15% FF addition were located at the far left of the score plot with a negative score while all other cookies were located 18

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M. Kaur et al.

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Fig. 2. a: Principal component analysis: loading plot of first principal component (PC1) and second principal component (PC2) describing the overall variation among measured properties of cookies from control sample and different composite flour mixes. Fig. 2b: Principal component analysis: score plot of PC1 and PC2 describing the variation among sensory evaluation scores of cookies from control sample and different composite flour mixes.

at right of the score plot with a positive score in the first principal component (Fig. 1b). The cookies prepared from 10% level of FF replacement were closest to the control sample in terms of their sensory scores. 4. Conclusion The present study was undertaken to see the potential of flaxseed in enhancing nutritional and antioxidant properties of cookies. The results revealed that flaxseed exhibited significantly higher fat, protein, ash and fiber content than wheat flour. Flaxseeds were found to be high in antioxidant potential as evident from higher TPC, free radical scavenging activity and reducing power of composite flour mix in comparison to control cookies. A significant reduction in antioxidant parameters upon baking, with higher loss in control sample than composite flour mixes cookies was observed. The increased level of flaxseed flour in the blends led to darker and browner appearance of the cookies. Therefore flaxseed can be successfully incorporated upto levels of 10% to wheat flour with reasonable acceptance offering nutritious, antioxidant rich and healthy alternative to consumers. It might be beneficial to further study how the storage duration and conditions will affect the quality characteristics and antioxidant potential of flaxseed fortified cookies or a related bakery product. Conflict of interest The authors have declared no conflict of interest. 19

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