Profiles of sturgeon protein prepared by two methods and the correlation between protein fractions and functional properties

In order to find the potential functional components in sturgeon protein, the protein fractions and functional properties of sturgeon proteins (SP) prepared by two methods were investigated, including pH-shift and subcritical dimethyl ether extraction (SDEE). In the case of the former method, four different experimental conditions were followed. The SP prepared by alkali-aided pH-shift had the highest salt-soluble protein content as well as the lowest water-soluble protein content, while the highest water-soluble protein content was observed in SDEE-produced SP due to a higher proportion of water-soluble protein that was retained during SDEE. Besides, the significant variations in almost all detected myofibrillar and sarcoplasmic fractions were observed across protein samples, which was mainly due to the solubility of various proteins under different preparation conditions. Moreover, the SDEE-produced SP possessed the greatest capacities in all the emulsification, foaming and gelation, followed by alkali-aided pH-shift and acid-aided pH-shift. In addition, the correlation analysis results indicated that enolase, aldolase, PM-2, TI, NDK, parvalbumin, actin and tropomyosin might be the primary functional components, while PM-1, CK, MLC3, degradation products and lipids had negative effects on its functional properties. Therefore, changes of the above components might be another important reason to explain how different methods affect the quality of protein, except for the degradation of protein.