Changes in Peptide and Free Amino Acid Contents of Different Bovine Muscle Homogenate during Storage

Peptide and free amino acid content in the seven muscles obtained from Holstein steer were investigated. Bovine muscles used were M. biceps femoris (BF), M. semimembranosus (SM), M. psoas major (PM), M. longissimus thoracis (LT), M. longissimus lumborum (LL), M. serratus ventralis (SV) and M. sternomandibularis (SB) 2 days after slaughter and were homogenized. The contents of peptides varied widely among muscles, ranging from 69.1 to 143.8mg and from 264.1 to 464.8mg per 100g meat 2 and 21 days after slaughter, respectively. Peptide contents in the BF and LL were higher than those of other muscles; the increments in peptides in these two muscles were also higher than those of other muscles during storage. On the other hand, the contents and increments in peptides in the SB were lowest during storage. Total free amino acid contents in the muscles were 83.3-154.3mg per 100g meat. These values were similar to those of peptide contents 2 days after slaughter. Total free amino acid contents in the muscles 21 days after slaughter measured from 176.0 to 220.6mg per 100g meat. Total free amino acid content in SB was the highest 2 days after slaughter, but its increment was the lowest during storage among muscles. The increment of total free amino acids was the highest in the LL during storage, although the content was the lowest 2 days after slaughter. These findings indicate that the activities of endgenous proteases vary widely among muscles. Ala content was the highest of the free amino acids in each muscle and increased only slightly during storage except PM. Glu content varied among the muscles and was higher in the SB than that of other muscles. Glu content in the SB was high 2 days after slaughter measuring 44.08mg per 100g meat.