Abstract: In this paper, effects of different freezing methods, including slow fridge freezing group at -20 oC, and rapid freezing groups (including at -20 oC, -40 oC, -60 oC and in liquid nitrogen respectively), on the biochemical characteristics of crabs stored at -20 oC, were evaluated in terms of pH, MDA contents, Ca2+-ATPase activity, total sulfhydryl content, and surface hydrophobicity. The results showed that during the storage at -20 oC, pH value, Ca2+-ATPase activity and total sulfhydryl content decreased, and MDA contents increased firstly and then decreased, while surface hydrophobicity increased continuously. The changing extents of each characteristic with rapid freezing methods were much lower than those with fridge freezing. Super-low temperatures, -60 oC and in liquid nitrogen, were better than the moderate low temperatures, -20 oC and -40 oC. But there’s no significant difference between -60 oC and liquid nitrogen.

Key words: Crab, Freezing rate, Protein, Lipid, Oxidation