FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

The freshness of hard clams stored at 30 and 25℃ can be maintained for 60 and 96 h, respectively. Its meat will turn black on reaching initial putrefaction, and off-odor will be noticed beyond these storage periods. The shelf life of hard clam was extended by cold storage, being 22 and 32 days when stored at 5 and 0℃, respectively; however, blackening and initial putrefaction with off-odor appeared when stored longer. Frozen storage can maintain the freshness of hard clams for a longer period, and its freshness was high when stored at -10 and -20℃ for 30 and 80 days, respectively. There was no obvious change in freshness during storage at -30℃ for 90 days. Neither blackening nor initial putrefaction appeared within 90 days when stored at -30, -20 and -10℃. Except for storage at -30℃, VBN and K value increased clearly and gradually during storage, especially when stored at -10℃. When the freshness of hard clams decreased, both VBN and K value indices increased. The difference between the critical points of these two freshness indices, judged from the initial putrefaction point, was clear. The critical
point of initial putrefaction of K value for hard clams stored at different temperatures changed with different increasing rates. On the contrary, those of VBN maintained the same value at different temperatures of storage, i.e., a level over 10 mg% indicated initial putrefaction.