Effects of Various Freezing Methods on the Quality of Prepared Abalone during Frozen Storage

To investigate the effects of freezing methods on the quality of frozen prepared abalone, steamed abalone was treated using −18 ℃ refrigerator freezing (RF_{−18 ℃}), −35 ℃ refrigerator freezing (RF_{−35 ℃}), −80 ℃ refrigerator freezing (RF_{−80 ℃}), liquid nitrogen freezing (LNF_{−80 ℃}), and immersion freezing (IF_{−30 ℃}). The freezing rates, physicochemical properties, and volatile components of abalone stored at −18 ℃ for 30 days were measured. The results showed that the times taken by abalone to pass through the maximum ice crystal zone were 81 min (RF_{−18 ℃}), 39 min (RF_{−35 ℃}), 31 min (RF_{−80 ℃}), 5 min (LNF_{−80 ℃}), and 13 min (IF_{−30 ℃}), respectively. Both LNF_{−80 ℃} and IF_{−30 ℃} groups effectively shortened the entire freezing period and were more efficient than RF in inhibiting the formation of TBARS and TVB-N. Abalone treated with LNF_{−80 °C} and IF_{−30 °C} exhibited a more compact microstructure. During frozen storage, the contents of nonanal and hexanal in abalone increased, leading to a stronger fishy odor. However, rapid freezing could delay the oxidation of lipids and proteins, thereby slowing down the deterioration of quality. Both LNF_{−80 ℃} and IF_{−30 ℃} effectively maintained the quality of abalone during the freezing process. However, from the perspective of energy consumption and equipment investment, IF_{−30 ℃} demonstrated higher cost-effectiveness. The findings of this study provide important theoretical and practical references for the selection of freezing technologies in the abalone processing and prepared dishes industries.