Effect of frozen storage conditions (temperature and length of storage) on microbiological and sensory quality of rustic crossbred beef at different states of ageing.

The effect of frozen storage conditions on meat from 36 Morucha×Charolais crossbred yearlings was studied. Slices of M. Longissimus thoracis were randomly assigned to groups arising from the combination of experimental factors. These factors were: ageing extent (3 and 10days), length of frozen storage (0, 30, 75 and 90days) and temperature (-20 and -80°C). Regarding microbiological counts, although values were acceptable in all cases, longer storage time and longer previous ageing extent provided higher phychrotrophic bacteria counts. As frozen storage period increased, colorimetric parameters L(∗), a(∗) and C(∗) decreased, but H(∗) increased. Regarding Warner-Braztler shear force and tenderness values, an interaction (p<0.05) between frozen storage and post-mortem ageing resulted from larger differences between frozen storage periods at shorter ageing periods than those at longer ageing periods. Frozen storage for 90days resulted in a reduction in water holding capacity, without differences in juiciness. No effect of freezing temperature was observed in any of the parameters studied.