EFFECTS OF KILLING, FREEZING AND THAWING CONDITION ON THE CHANGE IN PH, ATP CONCENTRATION AND AMOUNT OF DRIP IN THE ANCHOVY MEAT

摘要

Anchovy Engraulis japonica is one of the migratory species with big catch in Japan and its stock size is stable now. Most of anchovy is frozen after catch and thawed before processing. In order to clarify effects of killing, freezing and thawing condition on quality of anchovy meat, we examined the changes in pH, ATP concentration and amount of drip in frozen and thawed anchovy meat. Live Anchovy were killed by two methods and then frozen: dipping into liquid nitrogen immediately (instant dispatch and quick frozen, ID) or keeping in the air for one hour and then frozen by the dipping into liquid nitrogen (struggled dispatch, SD). Each specimen was stored at -30°C until experiments. Each sample was thawed by two methods of thawing: with running water (quick thawing, QT) or thawing at 0°C for 3hour and then keeping at 5°C at 2hour (slow thawing, ST).ATP concentration and pH in the meat of ID group were higher than SD group significantly. Most of ATP was degraded after struggled dispatch. The larger amount of drip was observed obviously in ID - QT group than SD- ST group after thawing. Most of ATP in the meat of ID was degraded during thawing. These results suggest that thaw-rigor could be caused by residual ATP under instant dispatch in anchovy meat during thawing.