Stepwise cooling mediated feasible supercooling preservation to extend freshness of mackerel fillets

Abstract

This study investigated the effect of supercooling preservation on the freshness and quality parameters to mackerel in comparison to chilled (refrigerated) and freezing condition. Stepwise cooling by 0.5 °C every 18 h was applied to preserve mackerel under a supercooled state for 12 days, and physicochemical properties were compared with chilled and frozen samples. The mean preservation temperatures (Tm) were 1.01 °C, −1.42 °C and −17.5 °C for the chilled, supercooled and frozen treatments, respectively. Freshness parameters indicated that supercooling effectively delayed both oxidative and microbial deteriorations, including total aerobic count (TAC), thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVBN) and trimethylamine (TMA), compared to chilled conditions. Based on kinetic analysis, the freshness holding period of supercooled mackerel was 9.51 days compared to 4.53 days of chilled mackerel. Although oxidative discoloration could not be prevented by supercooled preservation, supercooled mackerel showed better water-binding and textural properties than chilled or frozen mackerel after 12 days of storage. From the results, supercooling was effective to maintain fresh conditions (sashimi or sushi grade) of mackerel for more than twice the duration of chilled preservation.