Reduction of Oil Absorption in Deep-Fried, Battered, and Breaded Chicken Patties Using Whey Protein Isolate as a Postbreading Dip: Effect on Flavor, Color, and Texture

Authors


Abstract

ABSTRACT:  The effect of the application of whey protein isolate (WPI) solution as a postbreading dip to reduce oil absorption in deep-fried, battered, and breaded chicken patties on sensory properties was investigated. Chicken patties were battered, breaded with either crackermeal (CMP) or Japanese breadcrumbs (JBP), and dipped into WPI solutions at varying protein concentrations (0%, 2.5%, 5%, and 10%[w/w] WPI) and pH levels (pH 2, 3, and 8). A trained descriptive sensory panel evaluated the patties for 16 attributes relating to appearance, texture, and flavor. Instrumental analysis on the color and texture of the patties was also performed. The only perceivable changes in treated patties were related to color, hardness, and crunchiness. Increasing WPI concentration caused darkening of JBP but made CMP lighter. Patties treated at pH 8 were significantly darker across all WPI concentrations. The presence of WPI increased hardness and crust fracture for CMP but not JBP. Variations in pH levels did not affect texture. Thus, JBP that showed the highest lipid reduction (10% WPI at pH 2) were observed to be darker, less yellow, but did not produce any perceivable changes in hardness or crunchiness, while CMP with the lowest lipid content (5% WPI at pH 2) were lighter, more yellow, harder, and crunchier.

Introduction

The popularity of battered and breaded food products has risen worldwide (Antonova and others 2003; Patton 2005). Due to their popularity and the simultaneous rise in efforts to reduce fat intake, efforts to lower the fat content in fried foods have met with varying degrees of success in ensuring that the sensory expectations associated with the product are met (Fuller 2004). Methods to reduce fat absorption in fried foods such as shaking and draining of fried foods (Bouchon and others 2003; Mellema 2003) or careful monitoring of frying temperature and oil degradation (Math and others 2004) generally produce products with sensory characteristics very similar to the full-fat counterparts since these are usual practices in the frying industry (DGF 2000). However, strategies that alter the properties of the food, such as those that use ingredients to cover the surface of the breaded foods with lipid barriers, produce products with inconsistent sensory characteristics (Han and Gennadios 2005).

Desirable and expected properties of fried foods are crunchiness and golden-brown surface color. Fried foods that lack these attributes are usually perceived as being of poor quality and will not appeal to the majority of consumers. Measurement of crunchy texture may be achieved by measuring the force required to penetrate the crust region as a product is compressed or punctured, by measuring the acoustics produced during fracture, crushing, or mastication (Roudaut and others 2002), or both (Chen and others 2005). In breaded chicken, a system that has a dry-crunchy outer layer surrounding a moist substrate, force deformation information (Maskat and Kerr 2002; Sahin and others 2005; Acioli-Moura and Chang 2006; Brannan 2008) and ultrasound (Antonova and others 2003) have been used to objectively measure texture. The sensory perception of crunchiness includes taking into account both the intensity of the sound and force it takes to bite through the sample (Meilgaard and others 1999). Surface color is a quick and an often-effective parameter in determining the quality of fried foods. A darker color is the a usual outcome of foods fried in oil that have degraded or have been fried for too long and is often associated with off-flavors and low quality (Jackson and others 1999; Krokida and others 2001).

In a companion article, the use of whey protein isolate (WPI) as a postbreading dip to reduce oil absorption of breaded chicken patties was reported as a function of pH level and WPI concentration (Mah and others 2008). In order for this fat reduction strategy to be relevant as an industrial process, the effect on the organoleptic properties of the product must be known. The objective of this article is to determine the effect of WPI dips of different pH and WPI concentration on descriptive sensory analysis (appearance, texture, mouthfeel, and flavor) and instrumental color and texture of fried chicken patties.

Materials and Methods

Materials

All food ingredients were purchased from local retailers with the exception of whey protein isolate (WPI) which was provided by Volac Intl. Ltd. (Orwell, U.K.) and sodium bisulfate (pHase®) which was given by Jones-Hamilton Co. (Walbridge, Ohio, U.S.A.).

Sample preparation

Fresh boneless chicken breasts were cut by hand into approximately 4-cm cubes after all visible fat was removed. The meat pieces were ground once using a stand mixer with a food grinder attachment with coarse grinding plate (model K45SS/250W, KitchenAid®, Whirpool Corp., Mich., U.S.A.). Ground chicken was stored refrigerated (4 °C) for up to 2 h until needed. Twenty grams of chicken were formed into 5.1-cm-dia patties using a mold. Due to the large number of samples required, patties were stored frozen (−18 °C) for up to 24 h. The standard batter formulation was prepared by mixing deionized water with a dry mix of 48.75% wheat flour, 48.75% corn flour, 1.0% xanthan gum, 1.0% salt, and 0.5% baking powder (Sahin and others 2005). The batter was made fresh and kept cold until used. WPI solutions (0%, 2.5%, 5%, and 10%[w/w]) were prepared by mixing WPI with deionized water and adjusting the pH of the solution to pHs 2 and 3 using a low flavor impact, food-grade acidulant (sodium bisulfate), or pH 8 using baking soda (sodium bicarbonate). The whey protein isolate solutions were stored refrigerated for up to 1 d and were allowed to come to room temperature before use.

Patties were weighed, dipped in batter with excess gently shaken off, weighed again, coated with either Japanese breadcrumbs or crackermeal, weighed again, dipped in WPI solution, weighed again, then immediately fried. Control patties for each breading were placed directly into the deep fryer without dipping in the WPI solution. All patties were fried in 191 °C oil (canola oil with added dimethylpolysiloxane) in a deep fryer (Presto® Dual ProFry™/1800W, Natl. Presto Industries, Inc., Wis., U.S.A.) until an internal temperature of 74 °C was achieved. All temperatures were monitored throughout the process using an 8-channel thermocouple (Omega Industries, Grafton, Wis., U.S.A.). Cooked patties were allowed to drip for 15 to 30 s before being weighed, cooled to room temperature for 30 min, and placed in labeled freezer bags before being stored frozen (−18 °C) until analyzed.

Descriptive sensory analysis

Sensory testing was performed using a protocol approved by the Ohio Univ. Institutional Review Board for the protection of human subjects. A sensory panel consisting of 6 trained members was used to identify and evaluate 16 attributes in battered and breaded fried chicken patties (Table 1). The panelists participated in 17, 50-min training sessions prior to sampling of the crackermeal-coated patties (CMP) and Japanese breadcrumb-coated patties (JBP). Training and subsequent testing of products were based on the Spectrum™ method (Meilgaard and others 1999). Samples were rethermalized by baking at 191 °C until an internal temperature of 74 °C was obtained. Samples were held at 74 °C throughout a sampling session. Six randomized samples coded with a randomly generated 3-digit number were tested one at a time on a paper plate at each sampling session. Panelists were supplied with a set of standards for each attribute that they could use throughout the tasting session, shown in Table 1, unlimited water and unsalted saltine crackers, and a ballot with a 15-cm line scale anchored with standards and the value for the warm-up sample for each attribute. Prior to testing samples, panelists were presented a patty prepared in an identical manner to the undipped control patty that served as a warm-up sample. After the panelists were finished with the warm-up patty, it was removed before they analyzed any of the actual samples. Patties coated with crackermeal patties (CMP) were evaluated independently of Japanese breadcrumb-coated patties (JBP) in separate sampling sessions.

Table 1—.  Description and anchored references of sensory attributes generated by descriptive analysis of deep-fried, battered, and breaded chicken patties. Unless otherwise stated, the references were used for both Japanese breadcrumb-coated patties (JBP) and crackermeal-coated patties (CMP).
AttributeDescriptionReference/Brand/PreparationPosition (cm)a
  1. aPosition on 15-cm line scale.

  2. bGenerated by descriptive analysis panel.

  3. cAdapted from Meilgaard and others (1999).

ColorColor of the top surface of the sample (0 – yellow, 15 – dark brown)bCMP warm-up sample5.7
JBP warm-up sample10.4 
Evenness of colorEvenness of the color of the top surface of the sample (0 – even, 15 – not even/blotchy)bCMP warm-up sample7.9
JBP warm-up sample8.3
Greasiness of surfaceThe amount of grease that is perceived from looking at the top surface of the sample (0 – not greasy, 15 – greasy)bCMP warm-up sample6.6
JBP warm-up sample7.0
HardnessThe force that is required to bite through the sample with  incisorscCheese/pasteurized American/ 1/2-in slice4.5
CMP warm-up sample4.8
JBP warm-up sample5.4
Olive/Goya foods®/one giant size6.0
Frankfurter/Hebrew National®/ large, cooked 5 min/1/2-in slice7.0
Peanuts/Planters®/cocktail type in vacuum tin9.5
CrunchinessThe force and noise with which a product breaks or fractures  (rather than deforms) when chewed with the molar teethcDefrosted fries/Ore-Ida® Golden Fries/brought to room temperature1.2
CMP warm-up sample6.5
JBP warm-up sample8.9
Cereal/Quaker® Oatmeal squares12.7 
Moisture releaseThe amount of moisture released during a predetermined number of chewscCarrot/1 inch cubes2.0
Mushroom/button/quartered4.0
JBP warm-up sample4.0
Snap beans/1/2-in pieces7.0
CMP warm-up sample10.0 
Oily mouth coatingThe amount of oily coating that is perceived in the mouth cavity after the sample has been swallowed or expectoratedbJBP warm-up sample3.7
CMP warm-up sample4.1
Cold fries/Ore-Ida® Golden Fries/ deep-fried, cooled to room temperature6.0
SaltyThe amount of salty taste detected from the sample as it is being chewed before being swallowed or expectoratedbJBP warm-up sample1.3
CMP warm-up sample2.2
0.5% NaCl solution5.0
SweetThe amount of sweet taste detected from the sample as it is being chewed before being swallowed or expectoratedbJBP warm-up sample0.2
CMP warm-up sample1.0
5% sucrose solution5.0
SourThe amount of sour taste detected from the sample as it is being chewed before being swallowed or expectoratedbCMP warm-up sample0.1
JBP warm-up sample0.2
0.8% citric acid solution5.0
BitterThe amount of bitter taste detected from the sample as it is being chewed before being swallowed or expectoratedbCMP warm-up sample0.0
JBP warm-up sample0.0
0.8% caffeine solution5.0
UmamiThe amount of umami taste detected from the sample as it is being chewed before being swallowed or expectoratedbJBP warm-up sample0.0
CMP warm-up sample0.6
0.5% monosodium glutamate solution7.0
Chicken fat flavorThe amount of chicken fat flavor detected from the sample as it is being chewed before being swallowed or expectoratedbCMP warm-up sample3.7
JBP warm-up sample3.9
Render chicken fat9.6
ChickenyThe amount of chicken flavor detected from the sample as it is being chewed before being swallowed or expectoratedbCMP warm-up sample5.1
JBP warm-up sample6.4
Chicken breast/cooked in bag in boiling water for 15 min10.1 
Cooking oil flavorThe amount of cooking oil flavor detected from the sample as it is being chewed before being swallowed or expectoratedbCMP warm-up sample2.3
JBP warm-up sample4.9
Used frying oil/Canola oil with  added dimethylpolysiloxane9.7
Whey flavorThe amount of cooking oil flavor detected from the sample as it is being chewed before being swallowed or expectoratedbCMP warm-up sample0.8
JBP warm-up sample1.1
5% whey solution9.7

Texture analysis

Penetrometry tests using a Ta-XT2i texture analyzer (Texture Technologies Corp., Scarsdale, N.Y., U.S.A./Stable Micro Systems, Godalming, Surrey, U.K.) were used to evaluate the texture of the fried products. The textural attributes were crust fracture work, crust fracture force, total work, force ratio, hardness, resistance, as these were shown to be important attributes for battered and breaded chicken patties (Brannan 2008). Briefly, a 70-mm knife-blade probe on a solid flat platform at a crosshead speed of 10 mm/s was used to penetrate 10 mm into the sample. To assure that only a single edge of the crust was penetrated, samples were positioned such that only 25 mm of the sample, measured from the edge, was penetrated by the probe surface. The texture analyzer was controlled via Texture Expert Software.

Color analysis

The CIE L*, a*, and b* values of the fried patties after oven rethermalization were measured using a Konica BC-10 (Konica Minolta Sensing Americas Inc., Ramsey, N.J., U.S.A.). The meter was calibrated against a standard white plate before each use. The lightness (L*) and chromaticity coordinates (a*, b*) were calculated as the mean of 3 readings at different positions on the top surface of each patty.

Crust thickness

The crust was defined as the distance between the interface between the meat and coating and the outer surface of the patty. Crust thickness was determined by first cutting the patties in half and then measuring the thickness of the upper crust using a calibrated caliper. Three measurements were taken, one from the center of the cross section and two from a point 1 cm to the left and right of the center of the patty.

Statistical analysis

Two 3 × 4 full factorial designs were constructed for each breading system (crackermeal, Japanese breadcrumb) with 2 factors, pH levels (2, 3, 8) and whey protein solution concentration (0%, 2.5%, 5%, 10%). The complete design was replicated 3 times, although the 3rd replication was performed after the descriptive analysis was undertaken and was only used in the objective analysis.

Measurements on each of the 5 patties analyzed for texture were taken in duplicate and measurements on each of the 5 patties analyzed for color and crust thickness were taken in triplicate, then these values were averaged to give 1 value for each of the 5 patties analyzed per treatment. Thus, accounting for the 12 treatments within each breading system, means were generated for texture, color, and crust thickness from 60 patties per replication (180 total), plus 15 patties for each undipped control.

Means from descriptive sensory analysis for each of the 12 treatments within each breading system were generated from the individual ratings of the 6 panelists. For patties coated in Japanese Bread crumbs, each panelist sampled 1 patty per treatment for each of 2 replications (144 patties), plus 1 undipped control patty for each of the 2 replications (12 patties). Thus 156 patties were evaluated for this breading system. For crackermeal-coated patties, patties dipped in the WPI solution at pH 8 were not evaluated, so each panelist sampled 1 patty per treatment (96 patties), plus 1 undipped control patty for each of the 2 replications (12 patties). Thus, 108 patties were evaluated for this breading system.

All statistical analysis was performed using the SPSS statistical analysis software package (SPSS/v.14, SPSS Inc., Chicago, Ill., U.S.A.). Analysis of variance (ANOVA) was used to analyze differences between treatments and post hoc means separation was achieved using Duncan's multiple range test. Analysis of covariance (ANCOVA) was used to analyze the effects of cofactors on certain dependent variables. Pearson correlation coefficients were generated between certain sensory and objective measurements. The level of significance for all tests was set at P < 0.05.

Results and Discussion

The mean values for the weights of the raw patty, batter, breading, and whey pickup, and pre- and postfrying are shown in Table 2. There were no significant differences between the measured variables within a breading system. When measurements were compared between CMP and JBP, it was observed that the only significant difference was for breading pickup where the breading pickup for JBP was significantly higher (P < 0.05) compared to those for CMP. However, whey pickup and net loss were not significantly affected by the difference in breading pickup.

Table 2—.  Mean values for raw patty, batter, breading, and whey pickup, total weight pre- and postfrying, and difference in weight after frying for deep-fried, battered, and breaded chicken patties.
 Patty weight (g)Batter pickup (g)Breading pickup (g)Whey pickup (g)Total pickup (g)Weight prefrying (g)Weight postfrying (g)Weight difference (g)
Japanese breadcrumb-coated patties
pH level
 Control20.98.95.10.014.034.929.8–5.1
 pH 220.48.05.54.417.938.428.0–10.3 
 pH 320.48.55.84.418.639.228.6–10.5 
 pH 820.35.45.94.418.635.928.8–7.1
WPI concentration
 Control20.98.95.10.014.034.929.8–5.1
 0%20.57.55.73.916.737.627.4–10.2 
 2.5%20.39.05.74.218.839.128.4–10.7 
 5%20.48.76.04.319.039.429.6–9.8
 10%20.48.05.75.018.739.028.6–10.4 
Crackermeal-coated patties
pH level
 Control20.18.03.40.010.231.426.2–5.2
 pH 220.57.81.83.913.134.026.8–7.2
 pH 320.68.02.13.713.634.427.0–7.4
 pH 820.58.12.73.313.834.627.8–6.8
WPI concentration
 Control20.18.03.40.010.231.426.2–5.2
 0%20.67.91.33.411.933.226.0–7.2
 2.5%20.27.93.33.113.734.527.2–7.3
 5%20.97.92.03.813.434.627.7–6.9
 10%20.28.22.44.114.734.928.1–6.8

WPI solutions that are effective in reducing oil absorption require optimal conditions that result in WPI gel formation with all the properties of a lipid barrier, that is, low water-permeability values and good mechanical properties that allow for various manipulations (Gennadios and others 1997). These conditions are not likely to occur at or near the isoelectric point of WPI (pH 5.1) because of poor gel formation and little to no fat reduction was observed for patties treated with WPI solutions at its native pH in water (approximately pH 6.1) and at the isolelectric point (Brannan and Teyke 2006). Thus, WPI solutions in this study were tested at pH levels that are far from its isoelectric point, namely, pHs 2, 3, and 8.

Surface appearance

There was an obvious difference in appearance between patties treated with WPI dips at pH 8 compared to the undipped control and those at pHs 2 and 3. The samples treated with WPI at pH 8, regardless of WPI concentration, looked burned and unappealing. As shown in Table 3, lightness (L*) and both chromaticity coordinates (a*, b*) were significantly different for pH 8 than for the other samples. For JBP, L*, a*, and b* were all lower for pH 8 than in the undipped control or at pHs 2 or 3. In CMP, L* and b* were lower while a* was higher for pH 8 than in the undipped control or at pH 2 or 3. Fried foods often exhibit increased values for a* and lower values for L* and b* when they are fried under nonoptimum conditions such as long frying time, in highly degraded oil, and at very high temperatures (Krokida and others 2001; Ngadi and others 2007). For this reason and because patties treated with WPI at pH 8 exhibited minimal oil inhibition properties (Mah and others 2008), patties treated with WPI at pH 8 were not further analyzed by sensory analysis.

Table 3—.  Mean values (± standard deviation) for sensory color, evenness of color, and greasiness and instrumental color values (L*, a*, and b*) for deep-fried, battered, and breaded chicken patties as affected by pH and WPI concentration. Different letters indicate significant differences at P < 0.05 within an attribute for a treatment (a single breading system and pH or WPI concentration).
 SensoryInstrumental
Color (cm)Evenness of color (cm)Greasiness of surface (cm)L*a*b*
  1. WPI = whey protein isolate.

Japanese breadcrumb-coated patties
pH level
 Control10.1 ± 0.39.4 ± 0.56.7 ± 0.243.7a± 1.112.4a± 0.718.9a± 1.7
 pH 2 9.8 ± 0.28.5 ± 0.26.9 ± 0.141.8b± 1.212.0a± 0.518.4a± 0.6
 pH 3 9.7 ± 0.38.6 ± 0.26.8 ± 0.142.8ab± 1.0 12.7a± 0.418.9a± 0.6
 pH 835.8c± 1.4 9.6b± 0.411.3b± 0.9
WPI concentration
 Control10.1b± 0.3 9.4 ± 0.56.7 ± 0.243.7b± 1.112.4a± 0.718.9b± 1.7
 0%8.8c± 0.38.7 ± 0.26.7 ± 0.145.2a± 1.1 11.6abc± 0.5  21.0a± 0.7
 2.5%10.6ab± 0.4  8.2 ± 0.37.1 ± 0.138.7c± 1.3 11.9ab± 0.5 15.1c± 0.9
 5%11.4a± 0.4 9.1 ± 0.36.9 ± 0.237.7c± 1.6 11.4bc± 0.5 14.6c± 1.0
 10%11.3a± 0.3 8.4 ± 0.36.7 ± 0.238.1c± 1.510.9c± 0.614.1c± 0.9
Crackermeal-coated patties
pH level
 Control 8.7 ± 0.78.6 ± 0.76.2 ± 0.150.9b± 1.012.7b± 0.832.6a± 0.6
 pH 2 6.5 ± 0.37.8 ± 0.26.3 ± 0.254.1a± 0.6 9.6c± 0.457.9c± 0.6
 pH 3 6.8 ± 0.38.7 ± 0.36.1 ± 0.153.7a± 0.6 9.6c± 0.429.8b± 0.6
 pH 8 
WPI concentration
 Control8.5a± 0.78.6 ± 0.76.2 ± 0.150.9b± 1.0 12.7ab± 0.8 32.6a± 0.6
 0%5.2c± 0.38.2 ± 0.36.5 ± 0.156.0a± 0.7 7.7c± 0.4 27.7bc± 0.6 
 2.5%7.1b± 0.58.0 ± 0.36.0 ± 0.246.9c± 1.612.0b± 0.528.4b± 0.7
 5%6.6b± 0.47.9 ± 0.56.4 ± 0.245.6cd± 1.8  12.3ab± 0.5  26.7bc± 0.9 
 10%7.5b± 0.48.9 ± 0.26.1 ± 0.245.2d± 1.712.9a± 0.526.3c± 1.1

Panelists rated the appearance of the patties for color, evenness of color, and surface greasiness on an anchored 15-cm line scale. As shown in Table 3, no significant differences were observed for any of these attributes between patties treated at pHs 2 and 3 and with the undipped control. In JBP, patties treated with WPI at pH 2 were slightly but significantly darker (lower L* values) compared to the control patties. No differences were observed between the control and patties treated with WPI at pH 2 or 3 for either a* or b* values. In CMP, patties treated with WPI at pHs 2 and 3 were significantly darker (L*) and exhibited a significantly lower a* value than the undipped control. Analysis of CMP b* values shows that patties treated at pH 2 exhibited a significantly higher b* than the control, while patties treated at pH 3 exhibited a significantly lower b* than the control. These results suggest that pH of the WPI dip has more of an effect on the color of CMP than on JBP. This could be caused by hydrolysis of the complex carbohydrate in CMP producing reducing sugars which then are able to participate in nonenzymatic browning such as Maillard browing or caramelization. Research has shown that whey gels in the presence of honey exhibit an increase in a* and a decrease in L* when the pH of the gels is increased (Yamul and Lupano 2003).

The concentration of the WPI in the dips did not have an affect on evenness of color or greasiness of the surface of the patties for either breading system, but did influence color (Table 3). In JBP patties, color of the patties was observed as 0% WPI < control = 2.5% WPI = 5% WPI = 10% WPI. Thus, patties dipped in water (0% WPI) at varying pH levels, were more yellow than the control while patties treated with WPI were darker brown. This trend was reflected in the chromaticity coordinate b*, for which an increasing positive value indicates a more yellow color. In CMP, the color of the patties was observed as 0% WPI < 2.5% WPI = 5% WPI = 10% WPI < control. Thus in CMP, all dipped patties were less dark brown (more yellow) than the control; however, the opposite trend was observed for the chromaticity coordinate b*, as all WPI-treated samples were significantly less yellow than the control although all of the WPI-treated patties were lighter (L*) than the control.

Texture

The only texture sensory attributes that showed significant differences were hardness and crunchiness and only when WPI concentrations were varied for CMP (Table 4). Hardness was defined as the force required to bite through a sample (Meilgaard and others 1999) while crunchiness reflects the amount of sound and fracturability detected when the sample is chewed once with the molars (Vickers 1987). Sensory hardness for CMP was rated in the order of control = 0%= 5% > 2.5%= 10% WPI. When the results for objective values for hardness were analyzed, it was observed that CMP across all WPI concentrations were significantly harder compared to the control. Results from the sensory and instrumental measurements of hardness suggest that while variations in the pH levels of the dip do affect the hardness of the patties, changes in hardness can only be perceived in the presence of WPI.

Table 4—.  Mean values for sensory hardness and crunchiness, crust thickness (mm), and instrumental hardness, crust fracture, and crust work (g) for deep-fried, battered, and breaded chicken patties. Different letters indicate significant differences at P < 0.05 within an attribute for a treatment (a single breading system and pH or WPI concentration).
 SensoryInstrumental
Hardness (cm)Crunchiness (cm)Crust thickness (mm)Hardness (g)Crust fracture (g)
  1. WPI = whey protein isolate.

Japanese breadcrumb-coated patties
pH level
 Control 5.6 ± 0.37.2 ± 0.54.67 ± 0.47943.08 ± 83.82423.98 ± 70.85
 pH 2 5.2 ± 0.16.7 ± 0.34.36 ± 0.24945.31 ± 26.35409.93 ± 15.90
 pH 3 5.4 ± 0.16.8 ± 0.24.05 ± 0.161004.06 ± 32.74 404.09 ± 24.81
 pH 84.24 ± 0.15904.00 ± 21.60386.26 ± 18.11
WPI concentration
 Control5.6a± 0.37.2 ± 0.54.67 ± 0.47943.08 ± 83.82423.98 ± 70.85
 0%5.0b± 0.17.1 ± 0.34.22 ± 0.32993.39 ± 28.69391.08 ± 23.30
 2.50%5.4a± 0.26.9 ± 0.44.38 ± 0.19936.44 ± 39.13420.30 ± 25.45
 5%5.2ab± 0.2 7.0 ± 0.34.13 ± 0.18932.66 ± 31.69385.58 ± 24.44
 10%5.5ab± 0.2 6.6 ± 0.34.13 ± 0.15942.00 ± 27.07403.42 ± 18.54
Crackermeal-coated patties
pH level
 Control 5.8 ± 0.25.8 ± 0.53.04b± 0.32 651.53 ± 55.00194.63 ± 24.71
 pH 2 6.2 ± 0.16.0 ± 0.33.73a± 0.12 839.41 ± 28.86259.98 ± 12.56
 pH 3 6.4 ± 0.16.1 ± 0.22.92b± 0.11 862.80 ± 29.53247.29 ± 20.01
 pH 83.16b± 0.12 858.04 ± 28.32264.92 ± 16.38
WPI concentration
 Control5.8b± 0.25.8b± 0.5 3.04cd± 0.32  651.53c± 55.00  194.63b± 24.71 
 0%6.1b± 0.15.1b± 0.2 2.74d± 0.12 915.93a± 38.34  209.37b± 15.63 
 2.50%6.5a± 0.16.1b± 0.5 3.21bc± 0.14  851.08ab± 31.66  259.64a± 22.12 
 5%6.0b± 0.15.6b± 0.2 3.49ab± 0.13  813.22b± 24.23  267.12a± 15.94 
 10%6.6a± 0.17.4a± 0.3 3.64a± 0.15 850.65ab± 37.07  291.65a± 19.87 

As for crunchiness, CMP treated with 10% WPI was rated as having the highest intensity. Patties treated at other WPI concentrations were not significantly different compared to the control. An instrumental measurement that may correspond to perceived crunchiness is crust fracture (Brannan 2008) which represents the peak force at the point of crust thickness. Thus, higher crust fracture values imply a crunchier product. CMP treated with 2.5%, 5%, and 10% WPI were observed to have significantly higher crust fracture values compared to the control (Table 4) while CMP treated with 0% WPI were not significantly different compared to the control. The sensory and instrumental measurements of crunchiness suggest that treating patties with WPI increases the crunchiness of the patties independent of pH levels, and this effect could be more easily perceived at high WPI concentrations (for example, 10% WPI).

Since the instrumental measurements of texture involve the penetration of the crust region, it is suspected that the components of the crust such as the amount of batter, breading, and/or whey pickup and crust thickness. When ANCOVA was used to analyze the effects of these factors on CMP instrumental hardness, it was observed that only crust thickness significantly affects the instrumental hardness (P < 0.05). When the effects of these factors were analyzed for CMP crust fracture, it was also observed that only crust thickness significantly affected the variable (P < 0.05). Correlation analysis on crust thickness and instrumental hardness and crust fracture showed that crust thickness was positively correlated with crust fracture (r= 0.585, P < 0.01) but was not significantly correlated with instrumental hardness. These observations may explain why JBP did not show any significant differences for hardness and crust fracture (Table 4). Another factor that may contribute to the difference in crust fracture or crunchiness of the patties is the moisture content (Antonova and others 2003). Moisture content was observed to be significantly lower in CMP treated with 5% and 10% WPI (Mah and Brannan 200x). This may contribute to the significantly higher crust fracture for CMP treated with 5% and 10%. In addition, the sensory panel rated CMP treated with 10% WPI to be the crunchiest of all the treatments. Moisture reduces the crunchiness of a food product by weakening the solid matrix (Katz and Labuza 1981; Van Vliet and others 2004) due to breakage of the macromolecular interactions of the food structure by water–water interactions. This causes the macromolecules to be more mobile and slide against each other, and this is perceived as a reduction in crunchiness (Katz and Labuza 1981). Thus, the results suggest that treatments that lead to lowering of moisture content (for example, at 10% WPI) increases crunchiness of the battered and breaded product.

Mouthfeel sensations and flavor

The results for the sensory attributes that describe mouthfeel sensations and flavor are shown in Table 5. None of these attributes was observed to be significantly different compared to the undipped control and between treatments except for bitterness in JBP as WPI concentration is varied. Panelists rated those treated with 10% WPI to be significantly more bitter compared to the undipped control. However, since no other independent variable variations for both JBP and CMP produced a significant difference in bitterness, the observed result may be due to the psychological errors of the panelists and these errors may include those due to expectation, preference, environment, and fatigue (Stone and Sidel 2004). Further, the overall magnitude of the bitterness scores (0.0 to 0.2) were very small, suggesting that the very slight differences observed may not have much impact on overall quality. Overall, treating patties with WPI solutions at various pH levels and WPI concentrations did not significantly affect the general mouthfeel sensation and flavor of the patties.

Table 5—.  Mean values for rating of sensory attributes for deep-fried, battered, and breaded chicken patties. Different letters indicate significant differences at P < 0.05 within an attribute for a treatment (a single breading system and pH or WPI concentration).
 MouthfeelBasic tastesFlavor
Moisture releaseOily coatingSaltinessSweetnessSournessBitternessUmami flavorCooking oilChicken fatChickenyWhey
  1. WPI = whey protein isolate.

Japanese breadcrumb-coated patties
pH level
 Control5.0 ± 0.34.1 ± 0.21.1 ± 0.20.1 ± 0.00.1 ± 0.00.0 ± 0.00.2 ± 0.13.8 ± 0.33.7 ± 0.26.3 ± 0.31.4 ± 0.3
 pH 24.4 ± 0.13.8 ± 0.11.0 ± 0.10.1 ± 0.00.1 ± 0.00.1 ± 0.00.2 ± 0.03.9 ± 0.24.4 ± 0.85.9 ± 0.21.5 ± 0.2
 pH 34.2 ± 0.23.7 ± 0.11.3 ± 0.20.1 ± 0.00.1 ± 0.00.1 ± 0.00.2 ± 0.04.0 ± 0.23.7 ± 0.16.1 ± 0.11.7 ± 0.2
 pH 8
WPI concentration
 Control5.0 ± 0.34.1 ± 0.21.1 ± 0.20.1 ± 0.00.1 ± 0.00.0b± 0.0 0.2 ± 0.13.8 ± 0.33.7 ± 0.26.3 ± 0.31.4 ± 0.3
 0%4.4 ± 0.13.8 ± 0.11.0 ± 0.10.1 ± 0.00.1 ± 0.00.0b± 0.0 0.2 ± 0.13.9 ± 0.24.8 ± 0.96.3 ± 0.11.3 ± 0.2
 2.5%4.3 ± 0.23.8 ± 0.11.5 ± 0.40.1 ± 0.00.1 ± 0.00.1b± 0.0 0.2 ± 0.13.8 ± 0.23.8 ± 0.25.8 ± 0.21.8 ± 0.3
 5%4.4 ± 0.23.8 ± 0.11.1 ± 0.10.1 ± 0.00.1 ± 0.00.1ab± 0.0  0.1 ± 0.04.2 ± 0.33.7 ± 0.15.9 ± 0.11.8 ± 0.3
 10%4.2 ± 0.23.6 ± 0.11.4 ± 0.30.1 ± 0.00.1 ± 0.00.2a± 0.1 0.2 ± 0.03.7 ± 0.23.6 ± 0.15.7 ± 0.21.6 ± 0.2
Crackermeal-coated patties
pH level
 Control6.8 ± 0.54.3 ± 0.12.4 ± 0.11.2 ± 0.10.0 ± 0.00.0 ± 0.00.9 ± 0.22.8 ± 0.23.6 ± 0.25.6 ± 0.21.8 ± 0.3
 pH 26.8 ± 0.34.1 ± 0.12.2 ± 0.11.1 ± 0.10.1 ± 0.00.1 ± 0.00.7 ± 0.12.5 ± 0.13.6 ± 0.15.2 ± 0.11.5 ± 0.2
 pH 37.4 ± 0.34.1 ± 0.12.3 ± 0.11.1 ± 0.10.1 ± 0.00.1 ± 0.00.9 ± 0.12.4 ± 0.13.5 ± 0.15.3 ± 0.11.5 ± 0.2
 pH 8
WPI concentration
 Control6.8 ± 0.54.3 ± 0.12.4 ± 0.11.2 ± 0.10.0 ± 0.00.0 ± 0.00.9 ± 0.22.8 ± 0.23.6 ± 0.25.6 ± 0.21.8 ± 0.3
 0%6.9 ± 0.34.1 ± 0.12.2 ± 0.11.1 ± 0.10.1 ± 0.00.1 ± 0.00.8 ± 0.12.5 ± 0.23.7 ± 0.15.2 ± 0.11.5 ± 0.2
 2.5%7.0 ± 0.44.1 ± 0.12.1 ± 0.10.9 ± 0.10.2 ± 0.10.1 ± 0.00.7 ± 0.12.3 ± 0.23.3 ± 0.15.1 ± 0.21.6 ± 0.3
 5%7.9 ± 0.44.2 ± 0.12.5 ± 0.11.1 ± 0.10.0 ± 0.00.0 ± 0.01.0 ± 0.12.3 ± 0.13.7 ± 0.15.2 ± 0.21.7 ± 0.2
 10%6.8 ± 0.44.0 ± 0.22.1 ± 0.11.2 ± 0.30.1 ± 0.00.1 ± 0.00.8 ± 0.12.7 ± 0.23.4 ± 0.15.5 ± 0.21.2 ± 0.3

Conclusions

Treatment of deep-fried, battered, and breaded chicken patties with WPI did not cause any perceivable changes in the flavor of the product although color, perceived hardness, and perceived crunchiness were significantly affected. Despite the significant effect of the WPI postbreading dip on the color, hardness, and crunchiness of the deep-fried, battered, and breaded chicken patties, these changes may not deter consumers who place more emphasis on reducing their fat consumption. In short, while there is still room for improving this treatment to minimize the effect on color and texture, the usage of WPI as a postbreading dip is a promising alternative in reducing fat content in fried foods since it does not alter the flavor profile of a full-fat product.

Acknowledgments

This study was supported by the Natl. Dairy Council Discovery Pilot Program. The authors acknowledge Gary Saum and Grant Harris for technical support, and Bobbi Conliffe, Lisa Dael, Jody Grenert, Doug Grammar, Chris Sandford, and Keely Trisel for descriptive sensory analysis.

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