NUOVI SISTEMI DI INDAGINE PER LA CARATTERIZZAZIONE DELLA QUALITA' DELLA CARNE BOVINA

Variability of meat quality is a major concern for industry and consumers. Many factors can affect final meat quality, such as animal welfare, breeding, feeding and transport conditions, slaughtering conditions, electrical stimulation, and chilling conditions. All these factors interact in a complex way and lead to a high variability of muscular structure that characterizes the qualitative characteristic of meat. The aim of this work is to evaluate the whole muscle proteome to find some putative markers helpful for meat quality evaluation and for meat traceability. This work is divided in two different experimentally study. In the first experimental study proteomic technique were applied on samples of sternocleidomastoid muscle from Marchigiana breed in order to evaluate protein biomarkers to select novel parameter of quality. In order to reach the final goal the protein expression of muscle proteins was analyzed in relation with some important parameters of meat quality and production like: weight gain, slaughter age and the fat amount. 1D, 2D electrophoresis and Mass spectrometry were used to analyze the muscle proteome. In the second experimentally study two-dimensional electrophoresis and statistical analysis were applied to evaluate possible post-mortem differences between proteomic profiles in Limousine breed animals feeded with different diet supplementation in order to find putative biomarkers related to meat quality. The results of first experimentally study shown how the expression of 3 proteins (myosin heavy chain, actin and myosin light chain) is positively correlated with 3 key parameters of meat quality like: slaughter age, fat amount and the weight gain. On the other hand alpha actinin and tropomyosin b chain are negatively linked with the weight gain. Secondly the samples were analyzed with 2D electrophoresis. On the base of 9 differentially expressed spots we were able to clusterize the samples in 4 different groups of meat quality. The first group is the group with the best meat quality with the highest weight gain and the lowest amount of fat. The other groups are characterized by a progressive decrease of met quality. Results show how 1D and 2D electrophoresis could be used as new criteria of classification of animals and for the analysis of meat quality on the basis of expression of proteins in muscle. Moreover, these protein markers can be used together Quantitative Traits Loci to evidence the quality treats of meat and the origin of breed. The results of second experimentally study shown a gradually decrease in Expression of desmine and phosphoglucomutase 5 (PGM5) respectively in animal fed with vitamin complex and selenium for 60 days before slaughtering, for 30 days before slaughtering and control animal. Desmin is located in the intermediate filaments; it is responsible for the lateral structure and integrity of the myofiber because it holds adjacent myofibrils together at the Z-line level. The decrease of desmin may by related to a better color and tenderness of meat. The phosphoglucomutase is an enzyme that catalyzes the conversion of glucose 1-phosphate to glucose 6-phosphate. This enzyme is of great importance since it converts glucose 1-phosphate resulting from the mobilization of glycogen to glucose 6-phosphate is an intermediate glycosidic and therefore can enter directly into glycolysis. This could be due to stress events occurred in the pre-slaughter or during the slaughter process which caused a degradation of muscle glycogen stores. Treatment with a dietary supplement would seem to provide some sort of protection to those stressful events that may occur during the breeding or during slaughter and preserve the resources of glycogen and then ensuring the acidification of the body and lowering the pH to the correct values during the processes that lead to the transformation of muscle to meat. 2-DE-based proteome analysis is a powerful tool for characterize expression and metabolism of muscle proteins. Besides, analysis of expression profiles could be a key to find protein markers for meat quality, and to give deep understanding of characteristics of different welfare, breeding, feeding, transport conditions and slaughtering conditions.