Differences in carcass chilling rate underlie differences in sensory traits of pork chops from pigs with heavier carcass weights

Authors: PRICE, HANNAH - University Of Illinois; BARKLEY, KAYLA - University Of Illinois; LERNER, ANNIE - Kansas State University; HARSH, BAILEY - University Of Illinois; WOODWORTH, JASON - Kansas State University; TOKACH, MIKE - Kansas State University; DRITZ, STEVE - Kansas State University; GOODBAND, ROBERT - Kansas State University; DEROUCHEY, JOEL - Kansas State University; O'QUINN, TRAVIS - Kansas State University; ALLERSON, MATT - Holden Farms; FIELDS, BRANDON - Pig Improvement Company; King, David - Andy; Wheeler, Tommy; Shackelford, Steven; BOLER, DUSTIN - University Of Illinois; DILGER, ANNA - University Of Illinois

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2022
Publication Date: 6/21/2022
Citation: Price, H.E., Barkley, K.E., Lerner, A.B., Harsh, B.N., Woodworth, J.C., Tokach, M.D., Dritz, S.S., Goodband, R.D., DeRouchey, J.M., O'Quinn, T.G., Allerson, M.W., Fields, B., King, D.A., Wheeler, T.L., Shackelford, S.D., Boler, D.D., Dilger, A.C. 2022. Differences in carcass chilling rate underlie differences in sensory traits of pork chops from pigs with heavier carcass weights. Journal of Animal Science. 100(8). Article skac206. https://doi.org/10.1093/jas/skac206.
DOI: https://doi.org/10.1093/jas/skac206

Interpretive Summary: Since 1995, the average hot carcass weight of U.S. pork carcasses has increased at over 0.50 kg per year. While this represents an increase in efficiency, projecting continued increases in carcass weight in the future raises some concerns. For example, rapid increases in the size and weights of broiler chickens has created severe challenges in the poultry industry. This experiment showed that packing plants can effectively chill the very heavy carcasses that the industry will likely produce in the next 25 to 50 years. In the present study, all measures of tenderness were worse in carcasses that chilled more quickly than those that chilled more slowly. Thus, while chilling rate did affect pork tenderness, excessively fast and not excessively slow chilling was more of a concern.

Technical Abstract: Pork hot carcass weights (HCW) are increasing 0.6 kg per year and are projected to reach an average weight of 118 kg by the year 2050. This projection in weight is troubling for pork packers and processors given the challenges in product quality from heavier carcasses of other species, especially chicken. However, previous work demonstrated that pork chops from heavier carcasses were more tender than those from lighter carcasses. Therefore, the objective was to determine the effects of hot pork carcass weights, ranging from 90 to 145 kg with an average of 119 kg, on slice shear force and sensory traits when cooked to 71°C or 63°C, and the ability of differences in chilling rate to explain differences in sensory traits. Carcasses were categorized retrospectively into fast, medium, or slow chilling carcasses based on chilling rate during the first 17 h postmortem. Loin chops cut from 95 boneless loins were cooked to either 63°C or 71°C and evaluated for slice shear force and trained sensory panel traits (tenderness, juiciness, and flavor) using two different research laboratories. Slopes of regression lines and coefficients of determination between HCW and sensory traits were calculated using the REG procedure in SAS and considered different from 0 at P = 0.05. As hot carcass weight increased, chops became more tender as evidenced by a decrease in SSF (63°C ß = -0.0412, P = 0.01; 71°C ß = -0.1005, P < 0.001). Further, HCW explained 25% (R2 = 0.2536) of the variation in chilling rate during the first 5 h of chilling and 32% (R2 = 0.3205) of the variation in chilling rate from 5 h to 13 h postmortem. Slow and medium-rate chilling carcasses were approximately 12 kg heavier (P < 0.05) than fast chilling carcasses. Slice shear force of chops cooked to 63° and 71°C was reduced in slow and medium chilling compared with fast chilling carcasses. Carcass temperature at 5 h postmortem explained the greatest portion of variation (R2 = 0.071) in slice shear force of chops cooked to 63°C. These results suggest that carcasses tend to chill slower as weight increases, which resulted in slight improvements in sensory traits of boneless pork chops regardless of final degree of doneness cooking temperature.