Physicochemical and functional properties of protein isolate recovered from Rana chensinensis ovum based on different drying techniques.

This work was dedicated to evaluating the drying methods (freeze drying, spray drying, and vacuum drying) of food Rana chensinensis ovum protein isolate (RCOPI) based on comparison of the physicochemical and functional properties. The characterization and evaluation were conducted using scanning electron microscopy, surface hydrophobicity, SDS-PAGE, amino acid composition and nutritional parameters, Fourier transform infrared spectroscopy, and autofluorescence spectroscopy. The results showed the protein structure and conformation of RCOPI were greatly affected by drying techniques, leading to different physicochemical and functional properties. RCOPI possessed four main subunit bands distributed around 110, 90, 35 and 32 kDa. Seven essential amino acids were detected, accounting for 43.27-43.65% of total amino acids. Freeze drying RCOPI (FD-RCOPI) showed superior functional features, including solubility, water holding capacity, oil holding capacity, stabilization of Pickering emulsion and antioxidant capacity. FD-RCOPI exhibited applicability for the manufacture of viscous foods, bakery products and Pickering emulsions.