Study On Quality Changes Of Cultured Large Yellow Croaker Subjected To Different Freeze Methods

The quality changes of Large Yellow Croaker (Pseudosciaena crocea)during frozen storage after core temperature reaching-18℃by quick freezing were analyzed periodically for biochemical (WHC, pH, Salt soluble protein, Ca2+-APTase activity,-SH group), Texture Profile Analysis (TPA) (hardness, chewiness) and microstructure characteristics in this paper. The feasibility of Large Yellow Croaker freezing-frozen storage wasdiscussed.1. Based on the core temperature frozen curves of Cultured Large Yellow Croaker throughdifferent medium anddifferent quick freezing temperatures, we candraw the conclusion that:under the same quick freezing temperature, liquid-by samples passed the zone of most crystallization much faster than air-by ones, and reached-18℃faster; under the same quick freezing medium, the lower the quick freezing temperatures, the less time it passed the zone of most crystallization,the less time it reached-18℃.2. The results indicated that the effect of liquid-by quick freezing on Large yellow croaker(Pseudosciaena crocea) were better to retain their good quality characteristics and extend the shelf lifeduring frozen storage, which was supported by the result of biochemical, texture and microstructure characteristics. The results showed as follows:(1) WHC of both samplesdecreased graduallyduring frozen storage (P<0.05).The liquid-by samples got higher WHC than the air-by ones constantly, they got significantdifferences (P<0.05).(2)The value of pHdecreased initially and then increasedduring frozen storage (P<0.05). The liquid-by samples got later pH changes than the air-by ones constantly, they got significantdifferences (P< 0.05).(3)The content of salt solution proteinsdecreased graduallyduring frozen storage (P<0.05).The liquid-by samples got higher content of salt solution proteins than the air-by ones constantly, they got significantdifferences (P<0.05).(4) The value of Ca2+-APTasedecreased graduallyduring frozen storage (P< 0.05).The liquid-by samples got higher value of Ca+-APTase than the air-by ones constantly, they got significantdifferences (P<0.05).(5) The value of-SH groupdecreased graduallyduring frozen storage (P<0.05).The liquid-by samples got higher value of-SH group than the air-by ones constantly, they got significantdifferences (P<0.05).(6) The value of texture parameters (Hardness, chewiness)decreased graduallyduring frozen storage (P<0.05).The liquid-by samples got higher value of texture parameters (Hardness, chewiness) than the air-by ones constantly, they got significantdifferences (P<0.05).(7)The microstructures of liquid-by samples were better than the air-by ones.3. Under the conditions that the same quick freezing medium and the same frozen temperatures, the lower the quick freezing temperatures, the better quality and longer shelf life the samples would get.4. Under the conditions that the same quick freezing medium and temperatures, the lower the frozen storage temperatures, the better quality and longer shelf life the samples would get.5. The super chilling-frozen storage is a promising method for freshness preservation and extending shelf life.