Abstract: In the current study we optimized the ultrasonic-assisted enzymatic extraction of collagen from soft-shelled turtle calipash. One-factor-at-a-time method was used to investigate four factors affecting the extraction efficiency including enzyme dosage, ultrasonic time, ultrasonic power and solid-to-solvent ratio. Subsequently, a mathematical model with enzyme dosage, ultrasonic time and ultrasonic power as independent variables was established by Box-Behnken design. Meanwhile, we compared the thermostability of collagen extracted by routine enzymatic extraction and ultrasound-assisted enzymatic extraction. The optimal extraction conditions that provided the maximum collagen yield (74.50%) were determined as follows: 0.5 mol/L acetic acid as the extraction solvent, solid-to-liquid ratio 1:20 (g/mL), enzyme dosage 0.8%, ultrasonic time 43 min, and ultrasonic power 176 W. The results of differential scanning calorimetry showed that the thermostability of collagen extracted by the modified method was better than that of collagen prepared by conventional enzymatic extraction. The results of this study can provide a basis for intensitive processing and application of collagen from soft-shelled turtle calipash.

Key words: soft-shelled turtle calipash, optimization of ultrasonic-assisted enzymatic extraction, collagen, yield, thermal stability