EFFECTS OF GRAPE SEED POWDER AND WHEY PROTEIN ON QUALITY CHARACTERISTICS OF CHICKEN NUGGETS

Transcription

1 bs_bs_banner Journal of Food Quality ISSN EFFECTS OF GRAPE SEED POWDER AND WHEY PROTEIN ON QUALITY CHARACTERISTICS OF CHICKEN NUGGETS SEHER KUMCUOGLU 1 and ECE CAGDAS 2,3 1 Department of Food Engineering, Faculty of Engineering, Ege University, Bornova-Izmir, Turkey 2 Department of Food Engineering, Faculty of Engineering, Suleyman Demirel University, Isparta 32260, Turkey 3 Corresponding author. TEL: ; FAX: ; ececagdas@sdu.edu.tr Received for Publication March 11, 2014 Accepted for Publication November 24, /jfq ABSTRACT In this study, two different treatments and their effects on quality characteristics of chicken nuggets after three different cooking procedures were evaluated. Batters containing grape seed powder (GSP) dipped into whey protein solution (WPS) were compared with control (without any treatment) using deep fat frying, conventional oven and microwave oven. Batters contained equal amounts of wheat and corn flours with 5 and 10% GSP. All batters exhibited thixotropic behavior, and the GSP enhanced batters had lower viscosities. The lowest pickup values and highest total color change (ΔE) values were observed in deep fat fried samples. The microwaved samples had higher crispness levels and pickup values but achieved lighter colors that were identical to those of the pre-fried samples. Samples dipped into WPS provided reduced oil absorption consistent with their moisture contents. The scores for overall acceptability tended to decrease with the increase in GSP amount. PRACTICAL APPLICATIONS This study shows the effects of grape seed and whey protein solution treatments on batter quality as well as their interaction with cooking procedures. Although negative impressions toward battered and fried food products have been increased, consumers are becoming aware of health and nutritional food concepts. Therefore, new strategies are necessary in order to obtain healthier battered and fried foods without compromising the sensory quality. Grape seed powder is a promising ingredient as well as whey protein solution treatment as a post dip for improving the major components of frying batter in terms of textural properties, flow behavior, oil uptake and batter pickup. The results of this study could be helpful in the development of novel fried nuggets that include natural antioxidants having similar characteristics with grape seed powder. INTRODUCTION Ready-to-eat food products are becoming increasingly popular owing to changes in sociocultural behavior. Such changes in consumption patterns have led to the global demand for high-quality convenience foods, particularly those with crispy fried coatings. Due to this increased demand for ready-to-eat food products, it is important to improve batter ingredients. Also, the interaction of these ingredients must be analyzed to determine the overall performance of the product. Grape seeds containing 40% fiber, 16% oil, 11% protein and 7% complex phenols in addition to sugars and minerals are of increasing interest in food industry because they can improve the quality and nutritional value of food (Kim et al. 2006). Moreover, it has been viewed that it shows other biological effects such as anti-inflammatory and anti-ulcer activity. Therefore, it is interesting to investigate whether grape seed powder (GSP) addition to batter formula could enhance the batter quality. Biochemical changes in food materials to be fried are important factors in the final quality of the product as much as biochemical changes in frying oil. The addition of particular ingredients can change the interior color of the cooked batters; therefore, color evaluation techniques are used to improve the quality of the final product. In a study 83

2 QUALITY CHARACTERISTICS OF CHICKEN NUGGETS S. KUMCUOGLU and E. CAGDAS using chicken nuggets, Dogan et al. (2005) determined that as frying time increases, L* and hue values decrease and the a* value increases. In a similar study, Ngadi et al. (2007) determined that the decrease in L* value with frying time is associated with Maillard reactions at high frying temperatures. The crust that develops on fried or baked battercoated foods provides additional dimensions of texture and flavor, particularly in crispness and crunchiness. Such characteristics, which develop on the external layer during the cooking process, depend on the initial composition of the product and on frying temperature and duration. The effects of frying on the microstructure of battered squid rings were analyzed by Llorca et al. (2003) whereby they discovered an interconnection between the batter and the squid muscle in pre-fried products. One of the main quality factors in coated products is strong adhesion of the breading or batter. The degree of adhesion is related to yield; i.e., the amount of coating adhering to the outer layer of food is proportional to the total weight of the final fried product. Because the lack of adhesion at the interface is considered a severe quality defect, many studies have been conducted to develop techniques for enhancing the adhesive properties. For example, Fiszman and Salvador (2003) added hydrocolloids to basic formulae and Albert et al. (2009) implemented various cooking procedures to enhance the adhesion of batter. An additional issue is the considerable amount of oil absorbed during pre-frying and frying operations. It has been determined that the addition of particular ingredients can reduce the amount of oil absorbed by fried, battered products that include hydroxypropyl methyl cellulose (HPMC), methyl cellulose, powdered cellulose (Mukpraist et al. 2001), whey protein isolate (WPI) (Mah et al. 2008; Dragich and Krochta 2010), soy protein isolate, egg albumin, rice flour and soy flour (Dogan et al. 2005). Whey protein is composed of various proteins that can form induced gels. When whey protein is used as a coating, the porosity of the product can change, thus lowering moisture loss related to evaporation and oil absorption. The use of whey protein solution (WPS) provides nutritious and appealing final product in addition to reduction in oil absorption. Therefore, it would be beneficial to study the effects of WPS on quality of battered and fried products. During deep fat frying process, foods are cooked through contact with hot oil. The oil heated by the microwaves and the microwaves themselves simultaneously cook the interior of foods; therefore, heating time is reduced, and thicker foods are more uniformly heated by this process (Chen et al. 2009). Thus, research has been conducted on the application of microwaves in deep fat frying. In these studies, microwave frying was found to result in lower acrylamide formation in potato strips (Sahin et al. 2007) and in the coating of chicken (Barutcu et al. 2009). The recent trend toward improving quality of fried foods was about preparation of batter formulations with specific ingredients. For this consideration, GSP was utilized by mixing with major component of frying batter while WPS was used as a post dip prior to frying. We then evaluated the quality characteristics of chicken nuggets cooked in microwave oven, conventional oven and deep fat fryer. The results were compared with those dipped in a prepared batter and cooked by the same methods. MATERIALS AND METHODS Sample Preparation Deboned chicken breasts, wheat flour, corn flour, salt, a leavening agent (NaHCO 3), citric acid and sunflower oil (as frying medium) were purchased from local markets. GSP (Naturin Natural Products, Ltd., Izmir, Turkey) containing ± 0.86% moisture, ± 0.25% protein and ± 2.01% oil; HPMC (Sigma Aldrich, Steinheim, Germany); and WPI (BiPro, Davisco Foods Int., Minnesota) were also used in the experiments. Fresh chicken breasts were cut with a sharp knife into samples of 5 cm in length, 2 cm in width and 1 cm in thickness; each sample was weighed to ensure uniform weights of 15 ± 1 g. The chicken samples were then divided into two groups. The first group was immersed in batter prepared with GSP; the second group was immersed in batter prepared with GSP and then WPS. The same battering steps were used for both groups. Samples were immersed individually in different tempura/puff-style batters for 30 s and were allowed to drip for 10 s. Two batter formulations contained 100 g each of corn and wheat flours, 1 g of HPMC, 1 g of salt and 0.5 g of a leavening agent (NaHCO 3). GSP was added at 5 and 10% of the total dry mix, respectively. A batter without GSP was used as a control. All dry ingredients were thoroughly preblended and mixed with cold water (15C) at a 1:1.2 ratio (w/w) of solid to water. To ensure uniform mixing, the batters were blended with a hand mixer (Arçelik K-1433, Gebze, Turkey) at the lowest speed for 2 min. WPI powder (96% protein) was used to prepare WPSs. The WPS (10% w/w) was prepared by mixing whey protein with distilled water, and the ph of the solution was adjusted to 2 3 by adding food-grade citric acid. The solution was prepared and refrigerated 1 day prior to use and was held at room temperature for the analysis (Mah et al. 2008). A total of 2.1 L of sunflower oil was pre-heated for 45 min in a temperature-controlled deep fat fryer (Tefal OleoClean, Rumilly, France) to reach 180C. After preparing the chicken samples by immersion in the batter dough and in the WPS solution, they were pre-fried in batches of five samples for 30 s. Control, Control-WPS, 5% GSP, 5% GSP-WPS, 84

3 S. KUMCUOGLU and E. CAGDAS QUALITY CHARACTERISTICS OF CHICKEN NUGGETS Cutting into pieces with special size (5cmx2cmx1cm) GSP addition (5, 10%) Dipping in batter (30 s) Batter preparation Batter mix (wheat flour, corn flour, HPMC, salt, leavening agent) Draining (10 s) Treatment 1 Dipping in 10% (w/w) whey protein solution (WPS) (30 s) Draining (10 s) Treatment 2 Pre-frying (180 o C/30 s) Frozen storage (-18 o C/1 week) Thawing (4 o C/6 h) FIG. 1. FLOW DIAGRAM OF THE PROCESS MAKING BATTERED CHICKEN NUGGETS Deep fat frying (180 o C/4 min) Conventional oven (225 o C/11 min) Microwave (720 W/5 min) 10% GSP and 10% GSP-WPS refer to without GSP addition and not dipped into WPS, without GSP addition and dipped into WPS, 5% GSP addition and not dipped into WPS, 5% GSP addition and dipped into WPS, 10% GSP addition and not dipped into WPS and 10% GSP addition and dipped into WPS, respectively. The frying oil was replaced after each frying batch to maintain the level and was changed after 6 h of frying time. After frying, the samples were immediately removed from oil, cooled, placed in plastic freezer bags and stored at 18C for 1 week. The frozen samples were then thawed in a refrigerator for 6 h at 4C. To evaluate the effects of cooking type on the quality of pre-fried food, the samples were cooked in a deep fat fryer (Tefal OleoClean), a conventional oven (Siemens, HB301E0, Munich, Germany) and a microwave oven (Arçelik MD595, Gebze, Turkey) for 4 min at 180C, 11 min at 225C and 5 min at 720 W, respectively. The sequence of steps in the complete process is shown in Fig. 1. Batter Analysis The apparent viscosity of different batter formulations were measured using a concentric cylindrical rotational viscometer (model RVDV-IIIU, Brookfield Engineering, Middleboro, MA) equipped with a small sample adaptor (spindle SC-27). Time dependency of the batter was investigated by measuring the apparent viscosity under a constant shear rate of 50 s 1 for 300 s at 25C. The temperature of the batter samples was maintained during measurements using a circulating water bath. Moisture Content and Oil Content The moisture content was determined by drying the samples in a conventional oven at 105C to maintain constant weight (AOAC 1984). Oil content analysis was performed according to the method reported by Bligh and Dyer (1959) whereby oil was extracted using a methanol chloroform solution and diffused into a chloroform phase to determine its content. Batter Pickup and Cooking Loss After pre-cooked and cooked chicken samples were thawed, battered and nonbattered pieces were weighed in triplicate. The amount of batter adhering to a chicken sample, known as the pickup value, was calculated as: batter pickup (%)=( B ( B + S) )

4 QUALITY CHARACTERISTICS OF CHICKEN NUGGETS S. KUMCUOGLU and E. CAGDAS where B is the mass of batter remaining on the food sample after cooking and S is the mass of the food sample, excluding the batter, after cooking (Baixauli et al. 2003). Cooking loss was calculated as follows: cooking loss (%)=( R C) R 100 where R is raw nugget weight and C is the cooked nugget weight (Hwang et al. 2011). Color The color of the chicken sample crust was analyzed after pre-frying and after each cooking procedure using Hunter- Lab ColourFlex (HunterLab, Reston, WA) standardized against a calibration white plate, and readings were obtained on four different sections of each sample. The total color change, ΔE, was calculated using the following expression: ΔE = 2 2 ( L L ) + ( a a ) + ( b b ) where L 0, a 0 and b 0 are the reference values belonging to control samples, which did not include the addition of GSP. Texture The textures of the pre-fried and cooked coated chicken samples were determined using texture analyzer TA-XT2i (Stable Microsystems, Surrey, UK). The parameters used for testing were 3 mm/s for the pretest speed, 1 mm/s for the test speed and 10 mm/s for the post-test speed with a threshold force of 10 g to a distance of 5 mm. A stainless steel cylindrical probe 2 mm in diameter and a 5 kg load cell were used (Barutcu et al. 2009). The results were the arithmetic means of six measurements per sample expressed in g-force. Sensory Analysis The samples were served immediately after cooking. Pieces of cooked chicken nugget were presented to each panelist in random order in white plastic trays coded with threedigit numbers. Sensory testing was carried out using an untrained 50-member panel who was recruited from among the staff, undergraduate and graduate students at the Department of Food Engineering, Ege University. The sensory test was performed in individual cage and under fluorescent light in a standardized test room. Sensory characteristics were scored on a 7-point hedonic scale (1 = extremely dislike; 2 = much dislike; 3 = dislike; 4 = neither like nor dislike; 5 = like; 6 = like a lot; 7 = extremely like) for color, crispness, flavor and overall acceptability. Only one cooking method was tested per day. The entire experiment was performed in two replicates. Statistical Analysis All experiments were performed in two replicates. Analysis of variance (ANOVA) was performed to compare the effects of various cooking methods and batter formulations on quality parameters of chicken samples using SPSS 17.0 for Windows Evaluation Version (SPSS, Inc., Chicago, IL). Least significant differences were calculated by the Duncan test (P < 0.05). RESULTS AND DISCUSSION Flow Behavior of Batter Batter rheology is a key factor determining batter performance and important quality characteristics such as pickup, adhesion, appearance and texture as well as final moisture and oil content. Viscosity development within the batter was related to characteristics of dry ingredients. Therefore, the specific contribution of GSP to the viscosity of batter as well as its final quality was also evaluated. Time dependency of batters at constant shear rate of 50 s 1 was evaluated by determining the change in viscosity after 300 s. The changes in apparent viscosity with respect to time are illustrated in Fig. 2. All batters exhibited thixotropic behavior; the apparent viscosity decreased with an increase in mixing time. The same results were reported by Dogan et al. (2005) and Altunakar et al. (2006). Apparent viscosity was determined to be a function of GSP amount; the apparent viscosity decreased with an increase in GSP amount. This result may have occurred because GSP is an inert solid; therefore, increasing its amount reduces the percentages of other ingredients responsible for viscosity development. The control sample exhibited the highest viscosity, which might be partly owing to the high dispersibility of the flour mixture (Sanz and Salvador 2009). GSP-added batters may bound less water as compared with control samples. There may be more free water available for movement of particles in GSP-added batters providing low viscosity. Moisture and Oil Content of Chicken Nuggets The results of moisture and oil content analysis of the prefried samples are represented in Table 1. Moisture content is an important property in the quality of fried food products and is usually expressed as a percentage of quantity of water per unit mass of wet or dry product. Moisture contents in crusts after pre-frying changed between ± 0.34 and ± 1.90 and showed a tendency to increase with GSP amount (Table 1). The moisture loss in samples occurred at a significantly faster rate than that in samples prepared by dipping into WPS, which implies that more moisture 86

5 S. KUMCUOGLU and E. CAGDAS QUALITY CHARACTERISTICS OF CHICKEN NUGGETS Viscosity (Pa.s) FIG. 2. CHANGE IN BATTER VISCOSITY WITH MIXING TIME FOR DIFFERENT BATTER TYPES: ( ) CONTROL, ( ) 5% GRAPE SEED POWDER (GSP) AND ( ) 10% GSP Time (s) remained in the crust. The oil contents in the pre-fried crusts were 3.96 ± 0.66 to 8.26 ± 0.07; as expected, the oil contents of the crusts of samples dipped into WPS were lower. The interior temperatures of the samples increased during frying, which caused water evaporation and the formation of pores in the crust. The moisture in these pores might then be replaced by oil. Therefore, oil diffusion through the porous crust leads to a higher oil content and a lower moisture content in the crusts of fried foods (Sahin et al. 2005). These results are in agreement with those of Nasiri et al. (2012) who reported that a higher oil content corresponds with a lower moisture content. Most of the oil in the fried surface does not penetrate during frying; conversely, it is picked up at the end of the process. Oil adheres to the surface at the end of frying, and a high proportion penetrates into the food microstructure after frying is completed (Bouchon et al. 2003). Hence, batter containing thermal gelation ingredients has been studied along with preheating treatments to decrease the oil content of fried foods (Sanz et al. 2004; Salvador et al. 2006). The crusts containing higher amounts of GSP had higher moisture contents and lower oil contents owing to high pickup values. The WPS may have modified the surface structure of the samples by filling pores, thus preventing oil from collecting and reducing the surface area through which oil diffuses (Gamble et al. 1987). The higher moisture content of the samples containing a greater amount of GSP may have led to an increase in the surface tension of the coating, thus reducing the amount of oil absorption. Therefore, a sufficient amount of batter provided a coating outside the chicken to prevent excessive water evaporation during the frying process. The WPS layer on the surface of chicken may have diffused throughout the batter to modify the oil retention capacity of the entire crust. The majority of ingredients TABLE 1. MOISTURE AND OIL CONTENT OF CHICKEN NUGGETS Samples Pre-frying Deep fat frying Conventional oven Microwave oven Moisture (%) Control ± 0.34 ab ± 2.22 db ± 0.96 ba ± 0.39 cc Control-WPS ± 0.06 ab ± 1.36 db ± 0.64 bb ± 0.44 cf 5% GSP ± 0.98 ab ± 1.43 da ± 0.80 ba ± 0.34 cb 5% GSP-WPS ± ± 2.49 cb ± 1.14 bb ± 0.50 ce 10% GSP ± 1.28 ab ± 0.87 da ± 1.55 ba ± 1.19 ca 10% GSP-WPS ± ± 1.97 ca ± 0.37 bb ± 1.12 cd Oil (%) Control 8.26 ± 0.07 ba ± ± 0.08 dab 6.12 ± 1.12 ca Control-WPS 4.58 ± 0.16 cc ± 0.44 ac 4.62 ± 0.08 bca 5.85 ± 0.43 ba 5% GSP 6.94 ± 0.35 bb ± 0.14 B 4.64 ± 0.56 db 5.79 ± 0.25 ca 5% GSP-WPS 4.14 ± 0.17 cc 9.59 ± 0.77 ad 4.61 ± 0.15 cab 5.76 ± 0.29 ba 10% GSP 6.80 ± 1.06 bb ± 0.84 ab 4.51 ± 0.13 db 5.46 ± 0.64 ca 10% GSP-WPS 3.96 ± 0.66 bd 8.14 ± 0.38 ae 4.25 ± 0.29 bab 5.72 ± 0.29 a d Means within same rows with different superscript letters are significantly different (P < 0.05). A F Means within the columns with different superscript letters are significantly different (P < 0.05). GSP, grape seed powder; WPS, whey protein solution. 87

6 QUALITY CHARACTERISTICS OF CHICKEN NUGGETS S. KUMCUOGLU and E. CAGDAS that reduce oil content are film-forming or aqueous solutions of protein or nonprotein hydrocolloids that are either added to batter or applied as a post dip. Film-forming ingredients may not be practical but aqueous solutions composed of protein applied in a batter as a post dip may hold promise (Brannan et al. 2014). Moisture and oil contents of the fried samples are shown in Table 1. GSP level (0% = control, 5% and 10%) Dipping into WPS (no-dip, dip) Cooking procedure (pre-frying, deep fat frying, conventional oven, microwave oven) three-way ANOVA yielded significant GSP level Dipping into WPS (F = 3.228, P < 0.05), Dipping into WPS Cooking procedure (F = , P < 0.05) and GSP level Cooking procedure (F = 8.736, P < 0.05) interactions as a function of moisture content. There were significant differences in oil contents between cooking procedures on GSP level and dipping into WPS treatment. The dependence of oil content differences between cooking procedures on treatments (GSP addition and dipping into WPS) was reflected in a significant GSP level Dipping into WPS Cooking procedure interaction in overall ANOVA of these data (F = 3.199, P < 0.05). Further statistical analysis revealed a significant interaction between the cooking procedure and batter formulation. Although no significant differences were observed between oil contents of samples prepared by microwave oven and those by conventional oven, the moisture contents considerably differed. Cooking times for deep fat frying were less than those for the conventional oven method. However, deep fat fried and microwave-prepared samples did not have lower oil contents than samples cooked in the conventional oven. These results indicate that differences in oil content may not be attributed to frying time. The lower oil contents in the samples prepared in the conventional oven are associated with higher moisture contents (Table 1). Oil absorption occurs as moisture is removed from food during frying (Saguy and Pinthus 1995). Lower moisture contents and higher oil contents were observed in the deep fat fried samples, which occurred because the additional oil used in this method facilitates the interchange of water for oil during the frying process. For all cooking procedures, the presence of GSP and WPS aided in water retention, thus discouraging fat absorption. These findings confirm those of previous studies on the effectiveness of WPS against moisture removal and fat absorption in battered or breaded chicken patties (Mah et al. 2008) and in coated chicken breast strips (Dragich and Krochta 2010) during the frying process. Effect of Batter Formula and Cooking Procedure on Quality of Chicken Batter pickup is defined as the amount of batter adhering to a food substrate and is expressed as a percentage of the total product weight. A strong adhesion of the fried coating to the substrate in the end product is closely related to the adhesion of the raw batter at the time of application. The pickup values for various batter mixes and that using WPS as a post dip are shown in Table 2. Statistical analysis yielded significant GSP level dipping into WPS (F = 9.178, P < 0.05) and Dipping into WPS Cooking procedure (F = 4.294, P < 0.05) interactions for batter pickup values. Further analysis indicated that there was no three-way interaction due to the presence of a nonsignificant GSP level Cooking procedure (F < 1.000, P = 0.574) interaction for batter pickup values. The highest pickup levels were measured when the GSP amount was increased both after battering but prior to dipping into WPS and when only battering was employed. This might be due to the fact that the integration of GSP with the mixture sooner when used as an ingredient in basic batter caused an increase in the quantity of coating. These results are not in agreement with those reported by Soorgi et al. (2012), which may be due to differences in flour combinations in batter formulations. An analysis of the effect of batter formula for each cooking procedure revealed no significant differences between cooking methods and GSP amount for samples dipped into WPS. Higher pickup values were observed for only battered samples cooked in the microwave oven, whereas pre-fried samples and those coated with WPS showed lower values. The batters examined in the present study had higher pickup values, which differ from the results reported by Samples Pre-frying Deep fat frying Conventional oven Microwave oven Control ± 2.67 bb ± 0.25 bb ± 1.45 ab ± 1.12 ab Control-WPS ± 3.79 ac ± 2.69 ac ± 6.89 ac ± 2.16 ac 5% GSP ± 0.69 ca ± 1.13 cb ± 0.03 bab ± 0.05 B 5% GSP-WPS ± 3.60 ab ± 5.95 ab ± 1.69 ac ± 3.84 ac 10% GSP ± 1.19 ba ± ± ± % GSP-WPS ± 3.25 ab ± 1.22 ab ± 4.27 ac ± 6.08 ac TABLE 2. EFFECT OF DIFFERENT BATTER FORMULA AND COOKING PROCEDURE ON PICK UP (%) OF CHICKEN NUGGETS A C Means within columns with different superscript letters are significantly different (P < 0.05). a c Means within rows with different superscript letters are significantly different (P < 0.05). GSP, grape seed powder; WPS, whey protein solution. 88

7 S. KUMCUOGLU and E. CAGDAS QUALITY CHARACTERISTICS OF CHICKEN NUGGETS 30 Cooking loss (%) bb ab bb bb bc 5 0 Control Control-WPS 5% GSP 5% GSP-WPS 10% GSP 10% GSP-WPS Conven onal oven Microwave oven Deep fat frying FIG. 3. COOKING LOSS VALUES OF CHICKEN NUGGETS a,b Different lower case letters indicate significant differences between cooking procedures (P < 0.05). A,B Different upper case letters indicate significant differences between GSP treatment (P < 0.05) control. Albert et al. (2009). Such discrepancies may be attributed to differences in hydrocolloid content in batter formulas. Cooking loss values of chicken nuggets prepared with different cooking procedures are shown in Fig. 3. There was a significant Dipping into WPS Cooking procedure (F = , P < 0.05) interaction but there was not a significant three-way interaction due to the fact that no other reliable interactions were obtained for GSP level Dipping into WPS (F = 2.939, P > 0.05) and GSP level Cooking procedure (F = 1.636, P > 0.05). Cooking loss values of GSP-added samples were lower than that of control due to high moisture contents. Cooking loss values did not differ with batter pick up values as their results showed similar trend. Maintaining a proper coating with suitable viscosity is critical to ensure high coating yield levels (Yusnita et al. 2007). Even though the viscosity of control samples were high, it was observed that GSP addition result in low cooking loss values for the final product because of its high batter pickup values. It was found that GSP that shows low viscosity can be incorporated with wheat and corn flours that gave higher viscosity to produce good characteristics in the final product. Similar results were reported in Yusnita et al. (2007) who studied chicken wings battered with sago flours and Hwang et al. (2011) who studied chicken nuggets enhanced with Ganghwayakssuk. Texture is a sensory perception that can be described and quantified by only humans and generally described as a multiparameter attribute associated with mechanical, geometrical and acoustic parameters (Szczesniak 1987). During the frying process, the coating is dehydrated to result in a crisp outer texture while protecting the tenderness of the inner part. The textures of samples prepared using various methods are compared in Table 3 under consideration of GSP amount. The ANOVA results showed significant interaction between cooking procedure and treatments (GSP level and dipping into WPS) for hardness values. Further analysis yielded significant GSP level Cooking procedure (F = 3.218, P < 0.05) and Dipping into WPS Cooking TABLE 3. EFFECT OF DIFFERENT BATTER FORMULA AND COOKING PROCEDURE ON THE HARDNESS OF CHICKEN NUGGETS Samples Pre-frying Deep fat frying Conventional oven Microwave oven Control ± 4.75 cc ± ba ± ± Control-WPS ± cb ± ba ± ± % GSP ± cab ± bb ± ab ± ab 5% GSP-WPS ± ca ± bb ± aba ± ab 10% GSP ± cab ± bb ± ab ± ab 10% GSP-WPS ± ca ± ab ± abb ± bcc A C Means within columns with different superscript letters are significantly different (P < 0.05). a b Means within rows with different superscript letters are significantly different (P < 0.05). GSP, grape seed powder; WPS, whey protein solution. 89

8 QUALITY CHARACTERISTICS OF CHICKEN NUGGETS S. KUMCUOGLU and E. CAGDAS 50 be 45 bc Total color change ( E) ba ba ab bb cc dc ab bd cd dd ac ce de ad bf cf df cb Control Control-WPS 5% GSP 5% GSP-WPS 10% GSP 10% GSP-WPS Pre-frying Deep-fat frying Conven onal frying Microwave frying FIG. 4. EFFECT OF DIFFERENT BATTER FORMULA AND COOKING PROCEDURE ON COLOR OF CHICKEN NUGGETS a d Different lower case letters indicate significant differences between cooking procedures (P < 0.05). A F Different upper case letters indicate significant differences between grape seed powder (GSP) treatment (P < 0.05) control. procedure (F = 4.584, P < 0.05) interactions for batter pickup values. Further analysis indicated that there was no three-way interaction due to the presence of a nonsignificant GSP level Dipping into WPS (F < 1.000, P = 0.519) interaction for batter pickup values. The crusts of samples cooked in the microwave oven exhibited higher hardness values than those prepared by deep frying and in the oven in the conventional manner because more water is released from microwaved food in the form of steam. Conversely, conventionally fried samples dipped in WPS were harder than those prepared in the microwave oven because the coating part effective in absorbing the escaped moisture. Moreover, the energy necessary to reach the breaking point of the fried batter showed a significant decrease with an increase in GSP. Thus, compared with the control-battered samples, the use of GSP as an ingredient reduced the crunchiness of the samples in all of the cooking procedures examined. On the contrary, higher contents of GSP showed higher hardness values in the pre-fried samples. In general, samples dipped into WPS had higher hardness values than those dipped in only battered in all cooking conditions. Color is considered the most important visual attribute for product quality. The crusts of fried products exhibit a golden yellow color and play an important role in consumer preferences even before consumption. The golden color of fried crusts can be attributed to the Maillard reaction in which sugars are caramelized at higher frying temperatures. The color change occurring in the cooked and pre-fried samples was measured by HunterLab Colourflex; pre-fried control samples were taken as reference value (Fig. 4). GSP level (0% = control, 5% and 10%) Dipping into WPS (no-dip, dip) Cooking procedure (pre-frying, deep fat frying, conventional oven, microwave oven) three-way ANOVA yielded significant GSP level Dipping into WPS (P < 0.05), Dipping into WPS Cooking procedure (P < 0.05) and GSP level Cooking procedure (P < 0.05) interactions for total color change. The dependence of total color change differences between cooking procedures on treatments (GSP addition and dipping into WPS) was reflected in a significant GSP level Dipping into WPS Cooking procedure interaction in overall ANOVA of these data (F = , P < 0.05). The crusts containing more GSP showed darker color through Maillard reaction. The decrease in L* values during frying is a typical change that has been reported in research that included a variety of samples such as chicken nuggets and pork meat (Ngadi et al. 2007). L* values of the pre-fried samples and those cooked in the deep fat fryer, conventional oven and microwave oven were between ± 0.04 and ± 0.11, ± 0.08 and ± 0.06, ± 0.07 and ± 0.21 and ± 0.06 and ± 0.020, respectively. Therefore, the L* values of samples cooked with various methods were lower than those of pre-fried crusts. Microwave-fried samples acquired lighter colors that were identical to those of the pre-fried samples. The darkest samples were those cooked in the deep fat fryer, whereas the darkest crust 90

9 S. KUMCUOGLU and E. CAGDAS QUALITY CHARACTERISTICS OF CHICKEN NUGGETS TABLE 4. SENSORY SCORES FOR CHICKEN NUGGETS Cooking type Samples Crispness Color Flavor Overall acceptance Deep fat frying Control 6.1 ± 0.9 a 3.3 ± 0.7 a 6.2 ± 0.7 a 5.9 ± 0.8 a Conventional oven Microwave oven Control-WPS 6.2 ± 0.8 a 3.2 ± 0.7 a 5.8 ± 0.8 b 5.8 ± 0.9 a 5% GSP 6.1 ± 0.6 a 5.5 ± 0.9 b 5.8 ± 0.5 b 5.2 ± 0.7 b 5% GSP-WPS 5.4 ± 0.7 b 5.3 ± 0.7 b 5.2 ± 0.7 c 4.9 ± 0.9 b 10% GSP 5.2 ± 0.9 b 6.4 ± 0.6 c 5.3 ± 0.6 c 3.2 ± 0.7 c 10% GSP-WPS 4.7 ± 0.7 c 6.0 ± 0.6 c 4.6 ± 0.5 d 3.1 ± 1.0 c Control 5.5 ± 0.9 a 3.2 ± 0.7 a 5.9 ± 0.7 a 5.9 ± 0.8 a Control-WPS 5.2 ± 0.6 ab 3.0 ± 0.8 a 5.7 ± 0.7 ab 5.9 ± 0.9 a 5% GSP 5.0 ± 0.8 bc 4.4 ± 0.7 b 5.7 ± 0.7 ab 5.2 ± 0.7 b 5% GSP-WPS 4.6 ± 0.7 cd 4.1 ± 0.7 b 5.3 ± 0.7 bc 5.3 ± 0.8 b 10% GSP 4.5 ± 1.2 c 5.8 ± 0.7 c 5.2 ± 0.7 c 3.2 ± 0.7 c 10% GSP-WPS 4.2 ± 0.9 c 5.2 ± 1.1 d 4.7 ± 0.8 d 3.1 ± 1.0 c Control 3.9 ± 0.8 a 2.7 ± 0.8 a 4.3 ± 0.9 a 4.1 ± 0.7 a Control-WPS 3.5 ± 0.6 ab 2.7 ± 0.8 a 3.9 ± 0.9 bc 4.2 ± 0.9 a 5% GSP 3.6 ± 0.8 a 3.1 ± 0.7 b 3.9 ± 0.7 ab 3.9 ± 0.8 a 5% GSP-WPS 3.6 ± 1.0 a 3.1 ± 0.7 b 3.4 ± 0.7 d 3.8 ± 0.7 a 10% GSP 3.1 ± 0.9 bc 3.7 ± 0.5 c 3.4 ± 0.6 cd 3.2 ± 0.7 b 10% GSP-WPS 3.0 ± 0.8 c 3.2 ± 0.6 b 2.9 ± 0.7 e 2.9 ± 0.9 b a e Values with different letters in the same column and treatment are significantly different (P < 0.05). GSP, grape seed powder; WPS, whey protein solution. appeared on those cooked by the conventional oven after WPS dipping. The addition of GSP and application of WPS to the surface resulted in deepest red color, which is related to an increase in the amount of protein undergoing Maillard reactions. The chromatic color component a* increases with frying time and temperature as a result of the formation of compounds from the Maillard reaction. In this study, a* values increased with an increase in GSP amount and the maximum a* (8.39 ± 0.03) value was observed in 10% GSP nugget cooked deep fat fryer. Similarly, samples cooked with deep fat fryer showed the most dramatic color changes; those dipped in WPS and prepared in the conventional oven also showed extreme changes. The chromatic coordinate b* is related to physiologic perception of color: yellow or blue. The pre-frying stage will give the food a slightly golden initial color. Products coated with GSPadded batter acquire less b* values for all cooking treatments. The highest b* values were observed in deep fat fried samples (23.11 ± ± 0.04) while the lowest values were obtained from microwaved samples (20.77 ± ± 0.03). Total color changes were found as ± 0.41 and ± 0.19 for 10% GSP nugget cooked with deep fat fryer and 10% GSP-WPS cooked with conventional oven. The color changes in all samples significantly differed according to GSP amount and cooking method. Sensory analysis was conducted by 50 panelists to evaluate the acceptability of samples prepared with GSP and those with WPS. Test scores for crispness, color, flavor and overall acceptability of chicken nuggets were shown in Table 4. Sensory evaluation results revealed that GSP amount had a significant effect relative to cooking procedure. Overall acceptability ratings showed significant differences between control and those GSP-added samples, thus reflecting that consumers did not tend to prefer for nuggets including GSP. Generally, overall acceptability scores declined as the GSP amount increased. The color scores for deep fat fried and conventional oven-prepared samples were higher than those prepared by the microwave oven. The darkest crust contained 10% GSP and was deep fat fried, whereas the lightest sample belonged to the control and was prepared in the microwave oven. Crispness scores for deep fat fried control samples had the highest value, whereas those containing 10% GSP that were prepared in the microwave oven were deemed the softest samples. The sensory panel preferred the samples with higher crispiness scores. This result indicated that crispness attribute batter-coated samples was important for consumer acceptability. Control samples received significantly higher flavor ratings and overall acceptability scores, whereas those prepared in the microwave oven containing GSP showed opposite results. In all treatments, chicken nugget samples scored above minimum acceptable score of four were considered as acceptable. As a whole, scores for microwaved samples were four or lower than four which demonstrate that microwave samples were not acceptable. Similarly, the scores for 10% GSP and 10% GSP-WPS samples prepared with deep fat fryer and conventional oven were lower than 4 which demonstrate that those samples were not acceptable. When taking the chemical analysis results into 91

10 QUALITY CHARACTERISTICS OF CHICKEN NUGGETS S. KUMCUOGLU and E. CAGDAS consideration, the batter prepared using GSP and WPS that show good quality attributes could be improved for consumer acceptability. CONCLUSIONS The ultimate quality of fried, coated foods largely depends on the formulation of the ingredients constituting the raw batter. Batters containing higher amounts of GSP had higher water contents and lower oil contents. Although GSP used in batter formulations prevented fried foods from achieving the desired crispness, its addition improved the adhesion quality by increasing pickup values and produced darker crusts. The lower lipid contents were observed when WPS was used. Thus, it could be suitable in reducing in oil uptake and fulfill the steady demand for fried foods. Sensory analysis revealed that samples containing higher GSP amounts had lower acceptance scores. Therefore, both cooking procedure and GSP amount had a significant effect on the batter pickup rate in addition to the color and crispness of the samples. The usage of GSP as a batter ingredient and WPS for post coating could be promising alternatives to producing battered products with better quality attributes. Control and 5% GSP samples prepared with deep fat fryer were found to be the most acceptable samples as a result of sensory analysis. ACKNOWLEDGMENTS This research was conducted at Ege University and was supported by the Ege Science Technology Application and Research Center (EBILTEM) project number: 2011 BIL 017. The authors are also indebted to the Scientific and Technological Research Council of Turkey (TUBITAK) project number 110 O 512 for providing financial support. REFERENCES ALBERT, A., PEREZ-MUNUERA, I., QUILES, A., SALVADOR, A., FISZMAN, S.M. and HERNANDO, I Adhesion in fried battered nuggets: Performance of different hydrocolloids as predusts using three different cooking procedures. Food Hydrocolloid 23, ALTUNAKAR, B., SAHIN, S. and SUMNU, G Effects of hydrocolloids on apparent viscosity of batters and quality of chicken nuggets. Chem. Eng. Commun. 193, AOAC Official Methods of Analysis, 14th Ed., Association of Official Analytical Chemists, Arlington, VA. BAIXAULI, R., SANZ, T., SALVADOR, A. and FISZMAN, S Effect of the addition of dextrin of dried egg on the rheological and textural properties of batters for fried foods. Food Hydrocolloid 17, BARUTCU, I., SAHIN, S. and SUMNU, G Effects of microwave frying and different flour types addition on the microstructure of batter coatings. J. Food Eng. 95, BLIGH, E.G. and DYER, W.J A rapid method of total lipid extraction and purification. Can. J. Biochem. Physiol. 37, BOUCHON, P., AGUILERA, J.M. and PYLE, D.L Structure oil-absorption relationships during deep-fat frying. J. Food Sci. 68, BRANNAN, R.G., MAH, E., SCHOTT, M., YUAN, S., CASHER, K.L., MYERS, A. and HERRICK, C Influence of ingredients that reduce oil absorption during immersion frying of battered and breaded foods. Eur. J. Lipid Sci. Technol. 116, CHEN, S.D., CHEN, H.H., CHAO, Y.C. and LIN, R.S Effect of batter formula on qualities of deep-fat and microwave fried fish nuggets. J. Food Eng. 95, DOGAN, S.F., SAHIN, S. and SUMNU, G Effects of soy and rice flour addition on batter rheology and quality of deep-fat fried chicken nuggets. J. Food Eng. 71, DRAGICH, A.M. and KROCHTA, J.M Whey protein solution coating for fat uptake reduction in deep fat fried chicken breast strips. J. Food Sci. 75, FISZMAN, S.M. and SALVADOR, A Recent developments in coating batters. Trends Food Sci. 14, GAMBLE, M.H., RICE, P. and SELMAN, J.D Distribution and morphology of oil deposits in some deep fried products. J. Food Sci. 52, HWANG, K.E., CHOI, Y.S., CHOI, J.H., KIM, H.Y., KIM, H.W., LEE, M.A., CHUNG, H.K. and KIM, C.J Effect of ganghwayakssuk (Artemisia princeps Pamp.) on oxidative stability of deep fried chicken nuggets. Food Sci. Biotechnol. 20, KIM, S.Y., JEONG, S.M., PARK, W.P., NAM, K.C., AHN, D.U. and LEE, S.C Effect of heating conditions of grape seeds on the antioxidant activity of grape seed extracts. Food Chem. 97, LLORCA, E., HERNANDO, I., PEREZ, M., QUILES, A., FISZMAN, S.M. and LLUCH, M.A Effect of batter formulation on lipid uptake during frying and lipid fraction of frozen battered squid. Eur. Food Res. Technol. 216, MAH, E., PRICE, J. and BRANNAN, R.G Reduction of oil absorption in deep fried, battered, and breaded chicken patties using whey protein isolate as a post breading dip: Effect on lipid and moisture content. J. Food Sci. 73, MUKPRAIST, A., HERALD, T.J., BOYLE, D.L. and BOYLE, E.A.E Physicochemical and microbiological properties of selected rice flour based batters for fried chicken drum sticks. Poultry Sci. 80, NASIRI, F.D., MOHEBBI, M., YAZDI, F.T. and KHODAPARAST, M.H.H Effects of soy and corn flour addition on batter rheology and quality of deep fat-fried shrimp nuggets. Food Bioprocess. Technol. 5,

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