Development of laboratory methods to detect meat tenderness

Abstract

Tenderness has been identified as one of the most important attributes for consumers concerning their meat quality desire, so there is a clear need to accurately determine and grade meat accordingly to tenderness. A tenderness grading system has been proposed to be used to segregate carcasses in order to provide a more consistent prediction of eating quality to the consumers and also enable more carcasses to be segregated into the highest USDA quality grade and categorized as guaranteed tender. Known as an endogenous specific inhibitor of calpain, an enzyme responsible for proteolysis of myofibrillar proteins during post-mortem degradation of muscle, calpastatin presence in the muscle indicates that the activity of calpain can potentially be down regulated, resulting in meat toughness. Thus tenderness can be predicted with the assessment of calpastatin activity in the meat. Independent contribution of the sarcomere length to tenderness is also well established as classic scientific works have demonstrated that muscles with longer sarcomere lengths have lower resistance to shear force. Previous research have been done using enzymatic biosensor to predict calpastatin activity, this being a faster method compared to the traditional method, but the previous biosensor research might have been detecting fragments of inactive calpastatin. Hence more research was necessary in order to determine the rate of calpastatin degradation in samples, comparing quantity versus activity of calpastatin. In order to investigate the degradation of calpastatin mechanism and its activity an experiment was conducted using three different methodologies to measure calpastatin activity or quantity over a period of 180 total days. Longissimus dorsi samples from between the 12th and 13th rib of the beef carcass (n = 12) were extracted at 0 hour postmortem. These samples were assayed for calpastatin by the traditional method at day 0, and then kept under refrigeration until day 90 and day 180, when the same traditional assay was performed. Wh