Abstract: In order to study the effects of rinsing using NaHCO3 on the quality of fish subjected to repeated freeze-thaw cycles, the channel catfish was used as the research object, and the pH, thawing loss rate, fatty oxidation properties (acid value, 2-thiobarbituric acid value (TBARS)), protein solubility, protein oxidation properties(total sulfhydryl, active sulfhydryl, carbonyl), color of the fish were measured after 0, 1, 2, 4, and 7 freeze-thaw treatments, which are rinsed by different concentrations of NaHCO3. The results showed: after rinsing by NaHCO3, the pH value increased; the thawing loss rate decreased; the degree of fat oxidation decreased; the protein solubility increased; the degree of protein oxidation decreased. At the same time, the fat oxidation rate and protein oxidation rate of the fish after NaHCO3 rinsing were lower than those without NaHCO3 rinsing. It is indicated that the addition of NaHCO3 can improve the water-holding capacity of fish by inhibiting fatty oxidation and protein denaturation, and the 1.0 % NaHCO3 treatment group was more significant than the 0.5 % NaHCO3 treatment group. But as the number of freeze-thaw cycles increased, the pH value decreased significantly; the thawing loss rate increased significantly; the degree of fatty oxidation increased significantly; the protein solubility decreased significantly; the degree of protein oxidation increased significantly; the color of fish was significantly worse.

Key words: NaHCO3, freeze-thaw cycle, channel catfish, quality