Effects of treatment at a subzero temperature on pH, water retention, and metabolites in spotted mackerel (Scomber australasicus) muscle

Abstract

Studies have shown that storing pre-rigor frozen fish at subzero temperatures before thawing might suppress pH drop after thawing in some migratory fish. Therefore, the mechanisms involved in pH maintenance and the effects on the quality of fish muscle were investigated here. Frozen spotted mackerel (Scomber australasicus) was stored at −10 °C for 1–10 d (hereinafter referred to as “−10 °C treatments”). pH, water retention, and the changes in primary metabolite concentrations were investigated in the frozen and thawed muscles. When the −10 °C treatment lasted for 5 d or longer, the thawed muscle maintained a minimum pH of 6.2, and the water-retention and water-reabsorption capacities of the frozen-thawed spotted mackerel muscle of −10 °C treatment samples increased compared with the control sample. In the −10 °C treatments, nicotinamide adenine dinucleotide (NAD) was consumed and glycolytic intermediate products accumulated in the frozen muscle. This result suggests anaerobic glycolysis was inhibited. The results of this investigation indicate that −10 °C treatments before thawing may increase the meat quality in frozen spotted mackerel.