MICROCOPY RLSOLUION ILS CHART

It is well recognized that two structural components-collagen of the connective tissue and the actomysin complex of the contractile apparatus determine the tenderness of meat. Muscle collagen is com-prised of three genetically distinct types, each stabilized by lysine derived cross-links. As the animal matures the degree of cross-link-age increases relating to the textural alteration in the meat from older animals.- Textural changes not related to the age of the animal occur postmortem (after slaughter) in which the meat goes through a cycle of toughening (rigor) and tenderization. The natural tenderiza-tion following rigor occurs after 4 or 5 days postmortem and involves primarily changes in the interaction of two major elements of the con-tractile apparatus; myosin (the thick filament) and actin (the thin filament). Examination of the changes in the ultrastructure of the muscle during the natural tenderization process include: loss of the " ' band (a structure occuring periodically along the muscle fiber to which it is believed attaches thin filaments to each other), and changes in the distances between the thick and thin filaments. In 1973 Eino and Stanley (1) showed that a group of proteases in muscle produced structural alterations in muscle resembling those which occured during postmortem tenderization. These enzymes were released = maximally after 5 days postmortem. The group of enzymes are known to be acid hydrolases called cathepsins and are found within special organalles in the muscle called lysosomes. In 1976 Robbins and Cohen (2) of the Food Sciences Laboratory of NARADCOM, reported that muscle LA when treated with an extract of bovine spleen could be considered as an exogenous tenderizer which would simulate the natural aging process that occurs postmortem