Studies On Large Yellow Croaker In Partial Freezing

The quality changes of Large Yellow Croaker (PseucCosciaena crocea) during partial freezing by chilled salt water were studied in this paper. By analyzing and comparing the changes of sensory assessment, bacteria counts, physical-chemical indexes and tissue structure, the feasibility of Large Yellow Croaker storage by partial freezing was discussed. The results showed as follows:1. Partial freezing could restrain the growth of bacteria significantly, keep the T-VBN and K value at relatively low level. Total bacteria counts were 1.07X103CFU/g and T-VBN value was 15. 3mg/g after stored 30 days. The two indexes attained to the second grade of the national standard.2. Large Yellow Croaker was treated by freezing in 12% salt water at -8C after coating with 1% sodium alginate solution +2% Calcium Chloride solution, then storing at - 3C and -6C. Total bacteria counts and T-VBN value were lower than that of the contrast group, that indicate coating could restrain the growth of bacteria significantly, keep the T-VBN and K value at relatively low level.3. Coating with sodium alginate solution could keep the appearance of Large Yellow Croaker good and prolong the storage time. The appearance of Large Yellow Croaker on the 30th day kept original golden.4. After treated with salt water at low temperature, the salt content of Large Yellow Croaker stored at ~3C was 2.51% on the 30th day, but the salt content of coating Large Yellow Croaker was1. 03% on the 30th day. Coating could decrease the salt content of Large Yellow Croaker during salt water partial freezing.5. The water holding capacity of coating Large Yellow Croaker stored at -3C was 85. 22% on the 30th days which was 3% higher than that of the contrast group. Coating could strengthen the water holding capacity of Large Yellow Croaker during salt water partial freezing.6. Ca2+-ATPase activities of Large Yellow Crocker by salt water partial freezing decreased greatly.7. The changes of myofibrillar tissue of Large Yellow Croaker by partial freezing are lighter than freezing at -20C. Comparing Large Yellow Crocker storage at -3C with storage at -6C, the spaces among myofibrillar were smaller. Changes of myofibrillar tissue of Large Yellow Croaker by partial freezing were petty.8. Large Yellow Croaker stored by the four treating methods, its bacteria counts decreased fast during the first 15 days, then increased slowly. K value always fell down, T-VBN value increased slowly, Ca2+-ATPase activities dropped fast. But the data was different at the same period.