Effect of Ice Storage on Freshness and Biochemical, Physical, Chemical, and Microbiological Quality of Leg Muscle Samples from Bullfrog (Lithobates catesbeianus)

The present study evaluated the effect of ice storage on the freshness and quality of bullfrog (Lithobates catesbeianus) leg muscle. Biochemical, chemical, physical, and microbiological changes during 24 days of storage were analyzed. A rapid degradation of ATP into its intermediates (AMP, IMP, inosine, and hypoxanthine) was observed, with a significant increase in K-index (6.78% to 79.33%) and hypoxanthine concentration (3.93 ± 0.87 µmol/g), indicating a progressive reduction in freshness. The pH initially decreased due to post-mortem glycolysis but subsequently increased due to microbial activity and protein degradation. Volatile basic nitrogen (TVB-N) content increased significantly, reaching 27.36 mg/100 g, reflecting protein breakdown. A loss of texture was recorded, with a reduction in muscle firmness from 21.93 ± 1.36 Nw to 10.87 ± 1.08 Nw. Microbiological analyses showed an increase in bacterial load, with mesophiles and psychrophiles reaching 6.75 and 6.45 log CFU/g, respectively. These results indicate that the freshness and quality of bullfrog leg under ice storage remain within acceptable limits until day 18, but its quality and freshness decrease significantly toward the end of the study period.