Effect of Different Cooking Degrees on the Quality and Protein Digestibility of Procambarus clarkii

To investigate the effects of different cooking degrees on the quality and digestibility of crayfish (Procambarus clarkii), crayfish was cooked until the internal temperature reached 70, 80, 90, or 100 ℃. The changes in the moisture content, microstructure, and texture properties of crayfish meat were measured, along with the carbonyl and sulfhydryl content, surface hydrophobicity, secondary structure, and digestibility of proteins to identify the optimal cooking temperature for maintaining the quality and digestibility of crayfish meat. The results indicated that as the internal temperature of crayfish meat increased, the gaps between muscle fiber bundles widened, and surface hydrophobicity and water loss rose, resulting in increased hardness and reduced elasticity, ultimately causing quality deterioration. Additionally, increased internal temperature significantly exacerbated protein oxidation, as evidenced by a significant rise in the carbonyl content (P < 0.05), reaching 3.569 nmol/mg at 100 ℃. In contrast, the sulfhydryl content showed a significant decrease (P < 0.05). Protein oxidation induced protein cross-linking and aggregation, and moderate protein oxidation was found to enhance protein digestibility. The highest protein digestibility, 61.73%, was observed at an internal temperature of 90 ℃, which declined with increasing internal temperature beyond 90 ℃. In conclusion, different cooking degrees significantly affect the oxidation and digestibility characteristics of crayfish meat. An internal temperature of 90 ℃ results in moderate protein oxidation and optimal in vitro digestibility while maintaining appropriate hardness and elasticity, thereby preserving the overall quality of crayfish meat to the greatest extent.