AMONG ALL EATING QUALITY ATTRIBUTES, TENDERNESS IS OFTEN DESCRIBED AS THE MOST IMPORTANT FACTOR DICTATING THE OVERALL ACCEPTANCE OF COOKED BEEF, AS WELL AS, FUTURE DECISION TO REPEAT PURCHASE. WHILE MANY INTRINSIC AND EXTRINSIC FACTORS IMPACT END-PRODUCT TENDERNESS, VARIATION IN TENDERNESS IS USUALLY ATTRIBUTED TO THE EXTENT OF POSTMORTEM PROTEOLYSIS OCCURRING DURING MEAT AGING. SEVERAL PROTEOLYTIC ENZYME SYSTEMS, SUCH AS CALPAINS AND CASPASES, ARE KNOWN TO PLAY A ROLE IN POSTMORTEM PROTEOLYSIS AND HAVE BEEN EXTENSIVELY STUDIED. UNFORTUNATELY, HOWEVER, UNDESIRABLE VARIATION IN BEEF TENDERNESS STILL EXISTS. RECENT RESEARCH DEMONSTRATES THAT MITOCHONDRIA ABUNDANCE AND FUNCTIONALITY MAY BE INVOLVED IN MODULATING POSTMORTEM PROTEOLYSIS, ALTHOUGH THEIR EXACT ROLE IS UNKNOWN. MOREOVER, MITOCHONDRIA-MEDIATED CELLULAR EVENTS SUCH AS CALCIUM HOMEOSTASIS AND APOPTOSIS MAY GREATLY IMPACT END-PRODUCT TENDERNESS. FOR INSTANCE, THE ACTIVITY OF Μ-CALPAIN, THE MAJOR PROTEASE RESPONSIBLE FOR MEAT TENDERIZATION, IS DEPENDENT ON THE CYTOSOLIC CONCENTRATION OF CALCIUM, WHICH IS LIKELY MODULATED BY MITOCHONDRIA ABUNDANCE IN THE MUSCLE. YET, THESE "POWERHOUSES" OF THE CELL MAY LOSE THEIR INTEGRITY AS TIME PROGRESSES POSTMORTEM AND CONTRIBUTE TO POSTMORTEM PROTEOLYSIS THROUGH APOPTOSIS-INDUCED CASPASE ACTIVATION. MOREOVER, MITOCHONDRIA CONTENT IN POSTMORTEM MUSCLE MAY MODIFY THE PROTEOMIC PROFILE OF THE MUSCLE AND CONSEQUENTLY PROTEOLYSIS. THE RATIONALE THAT UNDERLIES THIS RESEARCH IS THAT ONCE WE HAVE IDENTIFIED THE MECHANISMS AND PROCESSES THROUGH WHICH MITOCHONDRIA IMPACT POSTMORTEM PROTEOLYSIS AND TENDERNESS DEVELOPMENT, THEN WE WILL BE BETTER POSITIONED TO: 1) OPTIMIZE THE TENDERIZING PROCESS; 2) PREDICT TENDERNESS DURING HARVEST; AND 3) PROVIDE THE MEAT INDUSTRY WITH THE NECESSARY TOOLS TO IMPROVE THE UNIFORMITY OF FRESH BEEF PRODUCTS. THIS, IN TURN, WILL RESULT IN INCREASED CONSUMER SATISFACTION AND ENHANCED ECONOMIC GROWTH OF THE US BEEF INDUSTRY.

Utah State University, Logan UT

Investigators