Abstract: More intensive research on the extraction of soybean protein isolate (SPI) may provide new possibilities for developing and utilizing plant proteins. In this study we made a comprehensive comparison between traditional alkali dissolution and acid precipitation method and reverse micellar extraction (RME) for soybean protein extraction and we investigated the unique properties of the reverse micellar environment. For this purpose, the structure, thermodynamic properties and rheological properties of SPI extracted from full-fat soybean powder by the two methods were studied. The results demonstrated that the SPI extracted by RME contained less β-sheet but more β-turn structure, representing a higher degree of unfolding, and therefore had a lower surface hydrophobicity. The reverse micelle environment could protect the protein from denaturation by organic solvents. The SPI extracted by RME had poor thermostability and was more prone to gelation, but the gel strength was lower when compared with the SPI extracted by the traditional method. Finally, we came to the conclusion that the unique water core structure of the reverse micelle could help to preserve the native structure of SPI.

Key words: reverse micelle, soybean protein isolate, molecular structure, thermodynamic properties, rheological properties