Analytical Aspects for Tropical Meat Quality Assessment

Meat tenderness is the most important quality attribute influencing consumer satisfaction and, therefore, meat consumption. The beef meat market in Brazil is going through transformation, and some quality traits, such as meat tenderness, begin to increase importance in the consumer choice at the time of purchase. However, even if the slaughterhouse industry applies criteria for carcass selection, in only 80 % of cases it correctly selects meat for tenderness. Consumer choice is guided by the observation of phenotypic characteristics, such as the amount of intramuscular, marbling score, and subcutaneous fats. Currently, Brazilian herds are basically composed by the Nellore breed (Bos indicus) and their crossbreeds, and it is very important to understand the influence of meat quality criteria on meat tenderness in Nellore cattle. Nellore breed animals possess a great capacity to accumulate subcutaneous fat. However, they do not have the ability to deposit marbling fat. Studies showed that the most important problem of Zebu breeds (Bos indicus) is represented by meat toughness, caused by a high activity of the calpastatin enzyme, an inhibitor of the proteolitic calpain system. The meat of zebu derived animals possess a high concentration and activity of calpastatin, which could explain the large variation of the meat tenderness of these animals. Animals subjected to intensive production systems in self-accelerated phases of the growth tend to present a higher meat tenderness. In this growth phase, muscle protein degradation is reduced, occurring with low protein turnover, and the activity of calpastatin is increased. It is observed that in all bovine breeds, some animals do not produce tender meat, even under favorable environmental conditions. In zebu breeds (Bos indicus), specifically in Nellore, the number of these animals tends to increase as they advance in age, and are slaughtered in the self-decelerating phases of growth.