Effects of natural and mechanical drying processes on unsaturated fatty acids, vitamin E, estradiol, and physicochemical properties of Rana chensinensis ovum

Abstract

Although Rana chensinensis Ovum (RCO) is enriched with high nutritional value, its quality varies due to the different drying methods used by farmers. This study aims to explore the impact of natural and mechanical drying methods on the nutritional compositions and physicochemical properties of RCO. Five different drying methods were studied, including blast drying (BD), mild breeze light drying (MBLD), natural air drying (NAD), vacuum heat drying (VHD), and vacuum freeze drying (VFD). The quality assessment was based on unsaturated fatty acid (UFA) content, iodine value, estradiol, vitamin E, saponification value, thiobarbituric acid value (TBA), acid value, and antioxidant properties. The results showed that VFD had higher UFA content and lower acid value (139.950 ± 0.397 mg · g−1) and TBA value (0.097 ± 0.003) than others. VFD and NAD had higher iodine values (147.166 ± 1.475 and 146.803 ± 1.209, respectively) than others. There were no significant differences in estradiol, vitamin E, peroxide value and the clearance rates of ABTS+ free radicals and DPPH• free radicals with different drying methods. The findings will provide valuable insights into the industrialization of RCO. Graphical Abstract: (Figure presented.)