Abstract
Beef sirloin (uscle longissimus thoracis) samples of 1 cm in thickness were aged at 0°C for 2-24 days, and the change in levels of inosine 5'-monophosphate (5'-IMP), lactic acid, free amino acids and oligopeptide-type amino acids were estimated. Such physical properties as the shear value, hardness, cohesiveness, penetration value and water-holding capacity of the aged beef samples were also measured before and after cooking at 209°C for 90 sec. In addition, the tenderness, intensity of umami taste and overall palatability of the aged and cooked samples were evaluated by a sensory test. As a result, the tenderness markedly increased as aging proceeded by both the sensory evaluation and objective measurement. Regarding the levels of free glutamic acid. (Glu) and 5'-IMP, both relating to the umami taste, the former increased while the latter decreased as aging proceeded. The intensity of the umami taste calculated according to the levels of these two components increased as aging proceeded, while that evaluated by the sensory test showed no significant increase. These results suggest that some components other than Glu or 5'-IMP would contribute to the intensity of the umami taste as evaluated by the sensory test.
