Comparison between high-pressure steam and vinegar stir-frying on grinding characteristics and nutrient components of turtle shells: Difference between carapace and plastron

The nutritional differences between the carapace and plastron of turtle shells, and their grinding challenges, are not well understood. This study aimed to evaluate the nutritional differences between a turtle shell’s carapace and plastron, and the effects of high-pressure steam (HP) and vinegar stir-frying (VS) pretreatments. The carapace showed higher crude protein and fat but lower ash than the plastron. Both pretreatments reduced grinding energy and increased ash content while decreasing protein and amino acids levels. HP resulted in more water-soluble extract (15.13%), protein (17.26%), and peptide (20.77%), whereas total free amino acids (FAAs: 545.62mg/100g) were increased by VS. Nutritional value was comparable between carapace and plastron. Additionally, in contrast to the conventional VS pretreatment approach, the HP method not only enhances the grinding process of turtle shells but also promotes the release of their water-soluble constituents. This advancement sets a solid foundation for future comprehensive studies aimed at exploring the nutritional potential of turtle shells.