Optimization of calcium removal in the carapace of Chinese soft-shelled turtle and structural characteristics of its collagen

Abstract

Objective: To improve the extraction rate and product purity of Chinese soft-shelled turtle （pelodiscussinensis）dorsal collagen. Methods: The decalcification rate and collagen recovery rate were used as evaluation indicators to investigate the effects of hydrochloric acid concentration, decalcification time, decalcification temperature and solid-liquid ratio on the decalcification of the carapace of Chinese soft-shelled turtle. The removal process of calcium salts was optimized, and the structural changes of decalcified and non-decalcified turtle carapace collagen were analyzed by SDS-PAGE, ultraviolet absorption spectroscopy, infrared absorption spectroscopy, amino acid analysis and other techniques under the same extraction conditions. Results: The optimal decalcification process conditions were hydrochloric acid concentration of 0.8 mol/L, decalcification time of 2 h, decalcification temperature of 28 ℃, and solid-liquid ratio of 1∶25 （g/mL）. Under these conditions, the decalcification rate and collagen recovery rate were （67.35±0.92）% and （90.77±1.08）%, respectively. The collagen content and extraction rate per unit mass of soft-shelled turtle carapace were significantly increased （P＜0.05） after decalcification with hydrochloric acid, but the structural characteristics of collagen did not change significantly. Conclusion: Hydrochloric acid has a good decalcification effect on the decalcification of turtle carapace, and has no effect on the structural properties of its collagen.

Keywords

• chinese soft-shelled turtle
• carapace
• decalcification process
• collagen
• structural characteristics