INTRODUCTION. H. C. Lee, M. A. Erasmus, J. C. Swanson, H. G. Hong, and I. Kang,,1

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1 Improvement of turkey breast meat quality and cooked gel functionality using hot-boning, quarter sectioning, crust-freeze-air-chilling and cold-batter-mincing technologies H. C. Lee, M. A. Erasmus, J. C. Swanson, H. G. Hong, and I. Kang,,1 Departments of Animal Science; Food Science & Human Nutrition; and Statistics and Probability, Michigan State University, East Lansing, MI ABSTRACT The effect of rapid carcass chilling on breast meat quality was evaluated using commercial (COMM) and random-bred (RB) turkeys. Immediately after slaughter, 48 turkeys from COMM or RB line were randomly subjected to one of four chilling methods: 1) water-immersion chilling (WIC) of the carcasses at 0 C ice slurry, 2) WIC after temperature abuse (TA) of the carcasses at 40 C for 30 min (TA-WIC), 3) hot-boning, quarter sectioning, and crust-freeze-airchilling (HB- 1 / 4 CFAC) of breast fillets at 12 C, and 4) HB- 1 / 4 CFAC of fillets after TA of carcasses (TA-HB- 1 / 4 CFAC). The TA increased carcass and fillet temperatures by 1.3 and 4.1 C, respectively, regardless of turkey line, whereas HB- 1 / 4 CFAC of fillets required 28 and 33% of carcass chilling time for COMM and RB, respectively. During chilling, COMM breast ph rapidly reduced from 6.04 to 5.82, resulting in a significantly lower ph than RB after chilling (P < 0.05), whereas COMM R-value sharply increased from 1.17 to 1.43, causing no difference from RB (P > 0.05). Significantly higher L value and cooking yield (P < 0.05) were seen in the samples of TA and WIC than those of no TA and HB- 1 / 4 CFAC, respectively, with no difference observed between COMM and RB fillets (P > 0.05). Higher values of hardness, gumminess, and chewiness were found for RB, no TA, and HB- 1 / 4 CFAC gels than COMM, TA, and WIC, respectively. These results generally indicated that protein quality and textural properties of turkey fillets were improved, regardless of strains or temperature abuse, using HB- 1 / 4 CFAC technology. Key words: turkey breast meat, hot boning, crust freezing, air chilling, cold-batter mincing 2016 Poultry Science 95: INTRODUCTION Consumption of poultry has continuously increased throughout the world including the United States (U.S.). According to the National Chicken Council (2015), per capita consumption of turkey increased from 7.5 lbs in 1965 to 15.7 lbs in 2014 in the U.S. As a result, the turkey industry has applied the method of quantitative genetic selection, which successfully increased turkey weight by double while reducing turkey growth time by half compared to those 50 years ago (Barbut et al., 2008). However, turkey processors noticed that these heavily muscled commercial turkeys showed meat defects similar to the pale, soft, and exudative (PSE) meat found in the pork industry (Ma and Addis, 1973; Ferket and Foegeding, 1994; McKee and Sams, 1998). Both genetic and environmental factors play a key role in the production of PSE meat. Chiang et al. (2008) reported that turkey breasts from a genetically- C 2015 Poultry Science Association Inc. Received April 2, Accepted August 27, Corresponding author: kangi@msu.edu selected commercial line had higher lightness value and lower marinade uptake than those from the genetically unimproved control line. In differential gene expression, Malila et al. (2013) indicated that the breasts of PSE turkey had disorganized muscle fibers and altered regulation of oxidative metabolism compared to those of normal turkey breasts. After exposing live turkeys to the control (16 C at night/24 C during day) or heat-stressed temperatures (32 C at night/38 C during day), McKee and Sams (1997) reported that the breasts from the heat-stressed turkeys showed faster ph decline, higher R-value, paler color, and more drip loss than those of turkey in the control temperature. During processing, McKee and Sams (1998) obtained turkey breast by hot-boning immediately after evisceration and exposed them to 0, 20, and 40 Cwaterfor 4 h. The breast at 40 C had increased drip loss, cooking loss, and L values compared to the breast exposed to 0 C. As a result, the environmental temperature before and after turkey slaughter was suggested to contribute to the development of PSE-like meat in addition to the geneticlineofturkey. In an attempt to mitigate these PSE-like defects during processing, Medellin-Lopez et al. (2014) subjected 138

2 QUALITY IMPROVEMENT OF TURKEY BREAST FILLETS 139 turkey carcasses to hot-boning, quarter sectioning and crust-freeze-air-chilling (HB- 1 / 4 CFAC) in a freezing room at 12 C. Results indicated that the fillets of HB- 1 / 4 CFAC had significantly higher ph and lower R-value than those of control carcasses in water-immersion chilling (WIC). Upon subjecting the HB- 1 / 4 CFAC fillets to cold-batter mincing, more protein was extracted with higher cooking yield than the traditional-batter mincing with control fillets. In a continued study, Lee et al. (2014) was able to reduce sodium content by 50% in protein gelation with no protein quality and functionality loss using the HB- 1 / 4 CFAC and cold-batter mincing technologies. Considering both genetic and environmental factors for the development of PSE-like meat, it will be interesting to assess the effect of HB- 1 / 4 CFAC and coldbatter mincing techniques on the meat quality using turkeys in two genetic lines. Therefore, the purpose of this study was to evaluate the effect of HB- 1 / 4 CFAC and cold-batter mincing on raw meat quality and protein functionality using turkeys in genetically-selected commercial and random-brad lines, with or without temperature abuse. MATERIALS AND METHODS Turkey Preparation and Carcass Chilling Commercial (COMM) (Hybrid Converter strain, Hybrid poults, Kitchener, On., Canada) and randombred (RB) poults (RBC2 line established in 1966; Nestor et al., 1969) were obtained from Cuddy Farms (ON, Canada) and The Ohio State University (Wooster, OH), respectively. To mimic a current commercial production system, COMM turkeys were reared to ± 0.29 kg (average live weight) in 15 to 17 wk and RB turkeys to ± 0.10 kg (average live weight) in 20 to 21 wk in the Michigan State University (MSU) Poultry Farm. Those turkeys were initially used for an open field test to measure fear characteristics of the two lines at MSU Poultry Farm and breast ph and R-value at 15 min postmortem after slaughter at MSU meat laboratory (Erasmus et al., in press). Following the initial field study, this study was conducted with three replications using the turkeys. In each replication, 16 COMM and 16 RB turkeys were used (96 birds as total) four weeks after the fear characteristics test to minimize any physiological effects from the previous research (Erasmus et al., in press). Turkeys were delivered from MSU Poultry Farm to Meat Laboratory after a 12-h feed withdrawal on three different days. Upon arrival, turkeys were electrically stunned for 6 s (80 ma, 60 Hz, 110 V) and bled for 90 s by severing both the carotid artery and the jugular vein on one side of the neck. Following bleeding, birds were subjected to scalding at 59 C for 120 s, de-feathering in a rotary drum picker (SP38SS automatic pickers, Brower Equipment, Houghton, IA) for 25 s, and manual evisceration. Immediately after evisceration and washing, turkeys were randomly subjected to one of four chilling treatments: 1) WIC of carcasses at 0 Cinaniceslurry, 2) WIC of carcasses at 0 C after temperature abuse (TA) at 40 C for 30 min (TA-WIC), 3) HB- 1 / 4 CFAC of fillets at 12 C/1.0 m/s as described by Medellin- Lopez et al. (2014), and 4) TA-HB- 1 / 4 CFAC of fillets after carcasses were in the TA. Before and after chilling, carcass and breast weights were measured while breast temperature was recorded initially and at 10 min intervals during chilling. ph and R-value Samples were obtained for ph and R-value at the cranial end of the left fillets after chilling. Breast ph was measured with a ph electrode (model , Fisher Scientific Inc., Houston, TX) attached to a ph meter (Accumet AR15, Fisher Scientific Inc., Pittsburgh, PA) after homogenizing 2.5 g of raw meat in 25 ml of distilled, deionized water (Sams and Janky, 1986). The R-value (ratio of inosine:adenosine) was measured as an indicator of adenosine triphosphate depletion in the muscle using the method of Thompson et al. (1987). Breast Color Measurement Commission Internationale de l Éclairage (CIE) L (lightness), a (redness), and b (yellowness) values were measured on the surface of skinless breast immediately after chilling, using a chromameter (8-mm aperture, illuminant C; CR-400, Konika Minolta Sensing Inc., Osaka, Japan) that was calibrated with a white plate (L, 97.28; a, 0.23; b, 2.43). Six readings of CIE L,a,andb were averaged for each value. Protein Gel Preparation from the Turkey Breast A protein gel was prepared with breast fillets using the method of Lee et al. (2014). Briefly, HB- 1 / 4 CFAC and TA-HB- 1 / 4 CFAC fillets were minced with 20% ice and 2% salt using a bowl chopper (model K64-Va, Maschinenfabrik Seydelmann KG, Aalen, Germany) at a blade speed of 4,000 rpm. WIC and TA-WIC fillets were conventionally minced with 4% ice, 16% water and 2% salt. The resulting batters were stuffed into preweighed stainless steel cylindrical tubes, reweighed, and placed into a water bath (model 25, Precision Scientific Co., Chicago, IL) at 80 C for 20 min. After cooking, the tubes were immediately chilled, sealed in plastic bags, and stored overnight in a refrigerated room (3 C). Cook Yields (CY,%) After chilling, the 4 parts of cooked gel in tube (stuffed tube, empty tube, removed gel, and tube cap)

3 140 LEE ET AL. were individually weighed to determine cooking yield, which was calculated by (cooked gel weight)/(raw gel weight) 100. Torsion Test A torsion test was used to measure true stress and true strain values of the cooked gels. Gel samples (3.0 cm long), which were cut perpendicularly, were milled into a dumbbell shape (10 mm in diameter at the midsection) using a shaping machine (KCI-24A2, Bodine Electric Co., Raleigh, NC) (Lee et al., 2014). Each specimen was placed on the sample holding apparatus in a viscometer (DV-III Ultra, Brookfield Engineering Laboratories Inc., Middleboro, MA) and twisted at 2.5 rpm. At the breaking point, both true shear stress and true shear strain were calculated with the recorded torque and elapsed time using the equations of Hamann (1983). Ten specimens were evaluated for each treatment for three separate replications. Water Holding Capacity Expressible Moisture Content (EM,%) EM was determined using the procedure of Jauregui et al. (1981). A sample (1.5 g) of cooked protein gel was weighed, covered with filter paper (Whatmann #3), and centrifuged at 1,000 g for 15 min (Sorvall-RC6 plus, ThermoFisher Scientific, NC). EM was calculated using the equation as: EM (%) = (weight of expressed water in filter paper /weight of sample) 100. Texture Profile Analysis (TPA) Gel samples (12.5 mm diameter and 13 mm height) were prepared and texture profile analysis was performed using puncturing apparatus and Texture Analyzer of Stable Micro Systems (TA-HDi, Texture Technologies, Corp., NY), respectively. In a two-cycles of compression test, sample height was compressed by 75% using a 500-N load cell at 1.67 mm/sec for the measurement of gel hardness (N), springiness (cm), cohesiveness, gumminess, and chewiness (Bourne, 1978). Statistical Analysis A completely randomized design with 3 replications and a 3 way factorial structure was used to analyze data with significance set at 5% using a PASW 18 statistic program (SPSS, 2011). Since there was no interaction among factors (P > 0.05), data were pooled and analyzed for each factor of strain and chilling method. RESULTS AND DISCUSSION The chilling time of the turkey carcass was affected by carcass size, carcass temperature, and chilling method Figure 1. Temperature changes of turkey carcasses in waterimmersion chilling (WIC) and breast fillets in air chilling after hotboning, quarter-sectioning for crust-freeze air-chill (HB- 1 / 4 CFAC) with or without temperature abuse (TA). A: Commercial (COMM) turkey B: Random-bred (RB) turkey. (Figure 1). After subjecting carcasses to temperature abuse (TA) at 45 C for 30 min, carcass temperature slightly increased from 41.5 to 43.0 CinCOMMand from 39.6 to 40.8 C in RB. Similarly, the temperature of deboned fillets from the TA carcasses increased from 38.4 to 42.4 C in COMM and 36.2 to 40.6 CinRB (Figure 1A, B). During chilling, the internal temperatures of COMM carcasses and fillets continuously decreased to 4 C, with average chilling times of 4.5 and 1.25 h for WIC and HB- 1 / 4 CFAC, respectively, which was delayed to 5.75 and 2.25 h with the TA. Similarly, the chilling time of RB carcasses and fillets was 2.25 and 0.75 h, respectively, which was extended to 2.75 and 1.5 h with the TA (Table 1). These results indicated that the required chilling time for fillets in HB- 1 / 4 CFAC and TA- HB- 1 / 4 CFAC was 28 and 50% of COMM carcasses in WIC, respectively, with 33 and 67% of RB carcasses for HB- 1 / 4 CFAC and TA- HB- 1 / 4 CFAC fillets, respectively (Table 1). Previously, our laboratory observed a similar chilling time (1 h) of COMM fillets in HB- 1 / 4 CFAC, with a different chilling time (5.5 h) of COMM carcasses in WIC (Medellin-Lopez et al., 2014). The difference for COMM carcass is expected due to the carcass weight difference. The average weight of live COMM turkeys was ± 0.29 kg in our study (Erasmus et al., in review), whereas the COMM turkey weight was 18 kg in the study of Medellin-Lopez et al. (2014). Sheridan (2000) indicated that the rates of carcass chilling are affected by intrinsic factors such as carcass mass, fat

4 QUALITY IMPROVEMENT OF TURKEY BREAST FILLETS 141 Table 1. Chilling time and chilling time difference of turkey carcasses and fillets for COMM and RB. Carcasses Fillets Treatments 1 WIC TA-WIC HB- 1 / 4 CFAC TA-HB- 1 / 4 CFAC Chilling time (h) COMM (28%) 2.25 (50%) RB (33%) 1.5 (67%) Chilling time difference (h) COMM - RB Treatments: strains (commercial, COMM; random-bred, RB), temperature abuse (TA), and chilling methods (water-immersion chill, WIC; hot-boning, quartersectioning and crust-freeze air-chilling (HB- 1 / 4 CFAC). Parenthesis shows the percentage (%) of chilling time as compared to that of WIC. content and initial carcass temperature as well as by extrinsic factors such as chill temperature, air or water speed, relative humidity and carcass spacing. In comparison to the end-chilling times, COMM carcasses and fillets required 2.25 and 0.5 more hours than those of RB, respectively, which was extended to 3.0 and 0.75 h with the TA (Table 1). Breast ph, R-value and color were measured after carcass chilling. With no interaction (P > 0.05) found among the treatment factors, means were pooled. The initial ph and R-value at 15 min postmortem was 6.04 and 1.17 for COMM, respectively, with 5.97 and 1.24 for RB (Table 2, Eramus et al., in press). During chilling, the COMM breast ph rapidly reduced to 5.82, resulting in a lower ph than RB breast after chilling (P < 0.05, Table 2). In response to the ph reduction, the COMM R-value sharply increased to 1.43, which caused no difference from RB after chilling (P > 0.05, Table 2). In 2014, Lee et al. (2014) reported that lower ph and higher R-value were seen in the fillets of HB- 1 / 4 CFAC than those of WIC carcasses at the completion of chilling. When hot-boned fillets were placed in different water temperatures, lower ph and higher R-value were observed at 40 than 0 C water as early as 15 min postmortem, the pattern of which was continued for 4 h (McKee and Sams, 1998). After chilling, both ph and R-values of breast fillets were lower and higher, respectively, than those of breast fillets before chilling (P < 0.05), regardless of strain, temperature abuse, and chilling method (Table 2). It is known that breast color is affected by age, genetic, and postmortem glycolysis of birds (Nishida and Nishida, 1985; Pietrzak et al., 1997; Debut et al., 2003). In color evaluation, a lower L (P < 0.05) was seen in the fillets of NTA and HB- 1 / 4 CFAC than TA and WIC, respectively, with no difference observed between COMM and RB fillets. It was reported that lower L value was observed in the fillets of no-stressed control than heat-stressed turkeys before slaughter, and in the fillets of postmortem aging at 0 than 40 C(McKeeand Sams, 1997, 1998; Chiang et al., 2008). In redness, significantly higher a values were seen in the fillets of NTA and HB- 1 / 4 CFAC than those of TA and WIC, with no difference observed between COMM and RB fillets. Huezo et al. (2007) indicated that the breast fillet of air chilled broiler was redder (higher a value) than that of WIC carcasses, which is similar to our results. Froning et al. (1978) reported that the fillets from heatstressed turkeys had higher a values than anesthetized birds when all birds were chilled for 24 h in ice slush. The different result are expected from the different experimental conditions between the two studies: heat stress treatment for live turkeys in Froning s versus hot conditions for the turkey carcass in ours and carcass chilling for 24 h in ice slush in Froning s versus carcass/fillet chilling for h in ours. Higher b values were found in COMM and HB- 1 / 4 CFAC than RB and WIC, while no difference was seen between TA and NTA (Table 2). After batters were minced and cooked, four parameters of cooking loss, expressible moisture, torsion test, and textural profiles were evaluated. With no interaction among the treatment factors (P > 0.05), means were pooled. A higher cooking yield was seen for NTA and HB- 1 / 4 CFAC gels than TA and WIC (P < 0.05), respectively, with no difference seen for COMM and RB gels (P > 0.05). In response to the cooking yield, lower expressible moisture was seen for NTA, HB- 1 / 4 CFAC, andrbgelsthanta,wic,andcomm,(p < 0.05, Table 3). Both higher cooking yield and lower expressible moisture content indicated higher protein functionality after heating and centrifugation. In the comparison of COMM to RB, Chiang et al., (2008) reportedthata higher marinade uptake was obtained from RB than COMM fillets when the fillets were finely chopped and incubated at 25 C for 30 min. Using COMM turkeys, a higher cooking yield was obtained in the cooked gels of turkey breasts in HB- 1 / 4 CFAC than those in WIC (Medellin-Lopez et al., 2014). Using a viscometer, both stress and strain values were measured. Stress and strain values were higher inrb,nta,andhb- 1 / 4 CFAC gels than COMM, TA, and WIC, except the strain in HB- 1 / 4 CFAC. Similar results of higher stress and strain values were found in HB- 1 / 4 CFAC than WIC gels (Lee et al., 2014). In the texture profile analysis, higher values of hardness, gumminess, and chewiness were found in RB, NTA, and HB- 1 / 4 CFAC gels than COMM, TA, and WIC,

5 142 LEE ET AL. Table 2. Pooled means (±SEM) of turkey breast meat quality obtained from two turkey strains before or after WIC or HB- 1 / 4 CFAC with/without temperature abuse. Strains Temperature abuse Chilling methods Parameter\factors 1 COMM RB NTA TA WIC HB- 1 / 4 CFAC Before chilling ph 6.03 a,2 (± 0.03) 5.98 a,2 (± 0.02) 5.99 a (± 0.03) 6.05 a (± 0.02) 6.04 a (± 0.03) 5.99 a (± 0.03) R-value 1.18 b,2 (± 0.02) 1.23 a,2 (± 0.02) 1.23 a (± 0.02) 1.19 a (± 0.02) 1.20 a (± 0.03) 1.21 a (± 0.02) After chilling ph 5.82 b, (± 0.02) 5.87 a, (± 0.02) 5.85 a, (± 0.02) 5.84 a, (± 0.02) 5.86 a, (± 0.01) 5.83 a, (± 0.02) R-value 1.43 a, (± 0.02) 1.41 a, (± 0.02) 1.40 a, (± 0.01) 1.44 a, (± 0.02) 1.42 a, (± 0.01) 1.43 a, (± 0.02) Lightness (L ) 51.2 a (± 1.2) 50.0 a (± 0.7) 49.2 b (± 0.8) 52.0 a (± 1.0) 52.7 a (± 0.9) 48.4 b (± 0.6) Redness (a ) 4.6 a (± 0.4) 4.9 a (± 0.3) 5.2 a (± 0.4) 4.2 b (± 0.2) 3.4 b (± 0.1) 5.7 a (± 0.3) Yellowness (b ) 1.3 a (± 0.6) 2.5 b (± 0.8) 1.6 a (± 0.8) 2.1 a (± 0.6) 3.9 b (± 0.3) 0.2 a (± 0.5) a,b Means with no common superscript within each row and factor differ (P < 0.05). Paired comparisons between before and after chilling ph and R-value (P < 0.05). 1 Factors: strains (commercial, COMM and random-bred, RB), temperature abuse (TA and no TA, NTA), and chilling methods (water-immersion chill, WIC and hot-boning, quarter-sectioning for crust-freeze air-chill (HB- 1 / 4 CFAC). 2 Data from the previous study (Erasmus et al., 2015). Parenthesis shows the standard error of the mean. Table 3. Pooled means (±SEM) of cooked turkey gels prepared from two turkey strains after WIC or HB- 1 / 4 CFAC with/without temperature abuse. Strains Temperature abuse Chilling methods Parameter\factors 1 COMM RB NTA TA WIC HB- 1 / 4 CFAC Functional properties Cook yields (%) 86.9 a (± 0.7) 87.0 a (± 1.2) 88.6 a (± 0.6) 85.2 b (± 1.0) 85.8 b (± 1.1) 88.0 a (± 0.7) Expressible moisture (%) 30.4 a (± 0.8) 26.8 b (± 0.9) 26.5 b (± 0.8) 30.7 a (± 0.8) 29.6 a (± 0.8) 27.6 b (± 1.1) Torsion tests Shear stress (kpa) 37.6 b (± 2.0) 51.7 a (± 3.0) 49.9 a (± 3.3) 39.4 b (± 2.6) 40.8 b (± 2.8) 48.5 a (± 3.4) Shear strain 1.04 b (± 0.04) 1.22 a (± 0.09) 1.25 a (± 0.08) 1.01 b (± 0.04) 1.07 a (± 0.06) 1.18 a (± 0.09) Texture profile analysis Hardness (N) 19.3 b (± 1.2) 24.8 a (± 1.0) 24.5 a (± 1.3) 19.6 b (± 1.0) 20.5 b (± 1.1) 23.6 a (± 1.5) Springiness 0.72 b (± 0.04) 0.78 a (± 0.02) 0.76 a (± 0.04) 0.75 a (± 0.06) 0.75 a (± 0.05) 0.75 a (± 0.05) Gumminess 9.2 b (± 0.8) 11.2 a (± 0.6) 11.8 a (± 0.7) 8.6 b (± 0.5) 9.1 b (± 0.6) 11.3 a (± 0.8) Chewiness 6.6 b (± 0.6) 8.7 a (± 0.5) 8.9 a (± 0.5) 6.4 b (± 0.5) 6.8 b (± 0.5) 8.5 a (± 0.7) a,b Means with no common superscript within each row for each factor differ (P < 0.05). 1 Factors: strains (commercial, COMM and random-bred, RB), temperature abuse (TA and no TA, NTA), and chilling methods (water-immersion chill, WIC and hot-boning, quarter-sectioning for crust-freeze air-chill (HB- 1 / 4 CFAC). Parenthesis shows the standard error of the mean. respectively, while a higher springiness value was found in RG than COMM (Table 3). It is reported that protein content has a positive correlation with gel toughness, firmness, hardness, and sensory panel firmness (Simon et al., 1965; Baker et al., 1969; Bloukas and Paneras, 1993). Rathgeber et al. (1999) also reported that delayed chilling reduced both stress and strain values of turkey breast gels, with lower protein extraction, reduced cooking yield, and increased L values. Given these findings, both protein quality and textural properties of turkey breasts appears to be improved in RB, no TA, and HB- 1 / 4 CFAC than COMM, TA, and WIC. CONCLUSION Crust-freeze-air-chilling (CFAC) is one of chilling technologies that can induce a rapid chilling of hot boned (HB) muscles for the improvement of protein quality and functionality. Cold-batter (meat paste) mixing is an emerging technology that can extract meat protein to a maximal level during the extended mixing without protein denaturation at cold temperatures. Using the combination of HB-CFAC and cold-batter mincing, the cooked gels showed higher cooking yield, higher stress/strain value, and better textural property than those of control gels, regardless of genetic strains and temperature abuse. These findings suggest that the technology of HB-CFAC and cold-batter mincing can shorten turkey chilling time, maintain protein integrity, and improve turkey meat quality after processing. ACKNOWLEDGMENTS The authors thank AgBioResearch at Michigan State University (East Lansing) and National Research Foundation of Korea (NRF) (2012R1A6A3A , Seoul, South Korea) for providing funding.

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