Freezing methods affect the characteristics of large yellow croaker (Pseudosciaena crocea): use of cryogenic freezing for long-term storage

Abstract Large yellow croaker (Pseudosciaena crocea) is the main coastal economic fish in China. After harvesting, the fish is rarely traded as the fresh product, but usually held in cold storage. Therefore, it is important to understand the quality changes occurring during preservation. In this study, freshly collected fishes were frozen by cryogenic (cabinet liquid nitrogen freezer at -40, -60 and -80 °C) and forced convection (ultra-low temperature freezer at -40 °C) freezing and stored at -18 °C for 6 months. Drip loss, relative moisture loss (RML), water holding capacity (WHC), color and texture of frozen fish were evaluated. The results showed that forced convection freezing had significantly higher drip loss and RML values compared to cryogenic freezing. WHC decreased dramatically irrespective of freezing methods employed. Cryogenic freezing at -60 and -80 °C had the highest yellowness values during storage; but the highest springiness, gumminess and shear force values were obtained only at -60 °C. We conclude that cryogenic freezing at -60 °C is appropriate for long-term storage of large yellow croaker.

摘要：大黄鱼（Pseudosciaena crocea）是中国主要的近海经济鱼类。该鱼种捕捞后极少以鲜品形式流通交易，通常多采用冷藏方式贮存。因此，明晰其在保藏过程中的品质变化具有重要的研究价值。
本研究将刚采集的新鲜大黄鱼分别采用深冷冷冻（-40℃、-60℃与-80℃柜式液氮冷冻机）与强制对流冷冻（-40℃超低温冷冻机）两种方式进行冷冻处理，并于-18℃条件下保藏6个月。随后对冷冻大黄鱼的滴水损失（drip loss）、相对水分损失（relative moisture loss, RML）、持水力（water holding capacity, WHC）、色泽与质构进行了检测与评估。
结果表明，相较于深冷冷冻组，强制对流冷冻组的滴水损失与相对水分损失值显著更高。无论采用何种冷冻方式，持水力均出现显著下降。保藏期间，-60℃与-80℃深冷冷冻组的黄度值最高；但仅-60℃组的弹性、胶着性与剪切力值达到峰值。本研究最终得出结论：采用-60℃深冷冷冻方式适配大黄鱼的长期保藏。