Influence of subzero temperature treatment before thawing on anaerobic metabolism, pH and dark meat color in frozen chub mackerel Scomber japonicus

Abstract

Subzero temperature treatment before thawing is a method expected to prevent the drop of pH in thawed fish meat as well as to maintain its quality. In this study, the changes in pH, NAD, ATP and lactic acid in frozen chub mackerel Scomber japonicus meat by subzero temperature treatment before thawing were investigated. The method did not effectively prevent the pH drop in thawed meat and promoted color deterioration of dark meat in the case of chub mackerel, whereas it effectively prevented the pH drop in thawed bigeye tuna meat.Moreover, it was revealed that the rate of decrease in NAD level in chub mackerel was lower than that in bigeye tuna during the subzero temperature treatment at-10°C before thawing. These results suggested that the drop in pH in thawed meat will be prevented by this method only in frozen fish meat having a rapid rate of NAD decrease during subzero temperature treatment before thawing.