Date of Award
Master of Science
Steven M. Lonergan
The objective of this study was to investigate the effects of blast chilling on sensory and proteolysis in cuts from the Longissimus dorsi (LM), Psoas major (PM), Semimembranosus (SM), and the Triceps brachii (TB). The SM was further divided into a superficial (SMS) and the deep (SMD) portions. Carcasses were selected for fat-free lean (FFL) and HCW approximately 45 minutes postmortem. Carcasses were split and sides were assigned to either blast chill (BC, -32° C for 90 minutes) or conventional chill (CC, spray chilled at 2°C for 24 h) regimens. BC sides had lower (P<0.05) temperature exiting chilling treatment (CC 21.8°C approximately 2 h postmortem, BC 9.7°C BC), 4 h (CC 13.3°C, 3.8°C BC), 22 h (CC 4.2°C, BC 1.4°C), and 30 h (CC 0.4°C, BC -0.2°C) as measured at the tenth rib in the LM. This was associated with a higher (P<0.05) pH in BC sides 4 h (CC 6.09, BC 6.34), 22 h (CC 5.81, BC 5.89) and 30 h (CC 5.68, BC 5.74) postmortem. Chilling regime resulted in higher (P<0.05) 30 h postmortem pH in the SM from BC sides (CC 5.68, BC 5.74). Cuts from BC sides had increased (P<0.05) purge loss in the PM (CC 0.48%, BC 0.74%) and increased (P<0.05) cook loss in chops from the LM (CC 22.37%, BC 24.24%). Trained sensory analysis (n=4) found that the PM from BC sides was more juicy (CC 7.50, BC 8.30), less chewy (CC 2.80, BC 2.10), and more tender (CC 7.90, BC 8.60). Chops from the LM of BC sides had greater Warner-Bratzler shear force (CC 2.00, BC 2.30). Color was affected in the SM with BC sides showing darker color score (CC 3.00, BC 3.20) and reduced Hunter a value (CC 16.35, BC 16.02). Chilling treatment did not have an effect on postmortem proteolysis across muscle groups. This study confirmed that chilling has different impacts across muscle groups which may be caused by location, rate of chilling, and fiber type.
Aaron M. Blakely
Blakely, Aaron M., "The effect of blast chilling on fresh pork quality in cuts from the Longissimus dorsi, Psoas major, Semimembranosus, and Triceps brachii" (2015). Graduate Theses and Dissertations. Paper 14335.