Location: Meat Safety & Quality Research
Title: Freezing and thawing or freezing, thawing, and aging effects on beef tenderness Authors
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 6, 2014
Publication Date: May 1, 2014
Citation: Grayson, A.L., King, D.A., Shackelford, S.D., Koohmaraie, M., Wheeler, T.L. 2014. Freezing and thawing or freezing, thawing, and aging effects on beef tenderness. Journal of Animal Science. 90(6):2735-2740. Interpretive Summary: When it comes to food, it is commonly believed that fresh is always better than frozen. However, for meat, two strategies using a freeze and thaw cycle may improve tenderness. The objective of this study was to determine whether freezing and thawing alone or freezing, thawing, then aging meat improves its tenderness. Steaks from the same loins were either evaluated fresh, after freezing and thawing, or after freezing, thawing and then aging at refrigerated temperatures. Steaks were more tender after freezing and thawing compared to fresh steaks likely due to the ice crystal damage to the meat structure during the freezing process. However, steaks subjected to freezing, thawing, then aging were the most tender. This was likely due to the enhanced enzyme activity during aging after freezing. These effects were similar for both loin steaks and eye of round steaks. These results indicate freezing could be incorporated into normal commercial product distribution processes to improve the consistency of meat tenderness. However, researchers who freeze steaks prior to tenderness assessment should be aware and acknowledge that freezing affects tenderness data.
Technical Abstract: The objective of this study was to determine the effect of freezing and thawing or freezing and thawing with an additional aging period after frozen storage on the tenderness of longissimus lumborum (LL) and semitendinosus (ST) steaks relative to aged, fresh steaks. Left-side LL and ST (n=35 each) were obtained from U.S. Select carcasses classified at the grading stand by the USMARC visible and near-infrared spectroscopy (VISNIR) tenderness system to have predicted slice shear force greater than 16.5 kg at 14 d postmortem. At 2 d postmortem, 2.54 cm steaks were cut from each muscle and assigned to one of the following treatments: 2 d fresh (2FRESH); 2 d freeze+thaw (2FREEZE); 2 d freeze+thaw+12 d age (2FREEZE+12AGE); 14 d fresh (14FRESH); 14 d freeze+thaw (14FREEZE); 14 d freeze+thaw+14 d age (14FREEZE+14AGE); and 28 d fresh (28FRESH). Steaks assigned to a freezing treatment were frozen at -26°C for 30 d prior to thawing/cooking or thawing with an additional aging period at 2°C. Slice shear force for LL and ST was lower (P < 0.01) for 2FREEZE (27.4 and 24.5 kg) and 14FREEZE (22.4 and 22.4 kg) compared to 2FRESH (33.0 and 29.2 kg) and 14FRESH (25.3 and 25.5 kg), respectively. Slice shear force for LL and ST was lower (P < 0.01) for 2FREEZE+12AGE (17.8 and 20.8 kg) and 14FREEZE+14AGE (14.6 and 19.0 kg) compared to 14FRESH (25.3 and 25.5 kg) and 28FRESH (18.7 and 21.7 kg), respectively. Desmin degradation for LL was not different (P > 0.05) between 2FREEZE (21.0%) and 2FRESH (14.6%) or between 14FREEZE (40.4%) and 14FRESH (38.4%), however, desmin degradation was higher (P < 0.01) in 2FREEZE+12AGE (48.2%) and 14FREEZE+14AGE (72.0%) when compared to 14FRESH (38.4%) and 28FRESH (60.5%), respectively. Cooking loss for LL was higher (P < 0.01) in 2FREEZE+12AGE (15.2%) compared to 14FRESH (14.0%), but was not different (P > 0.05) between 14FREEZE+14AGE (15.0%) and 28FRESH (14.3%). Freezing and thawing or a combination of freezing, thawing, and aging resulted in improvements in tenderness for LL and ST steaks when compared to fresh steaks with the same aging time. These results indicate freezing could be incorporated into normal commercial product distribution processes to improve the consistency of meat tenderness. Researchers who freeze steaks prior to tenderness assessment should be aware and acknowledge that freezing affects tenderness data, with the greatest effect on tougher meat.