Effects of cavitation jet on structure and emulsifying properties of soy protein isolate

Soy protein isolate has a reasonable protein composition ratio- It is not only cholesterol-free but also contains essential fatty acids, phospholipids, and rich minerals such as calcium and phosphorus. Cavitation jet is a new technology that can produce cavitation phenomenon. This technology can change the structure of pea globulin aggregates and enhance its emulsion stability. It can also significantly affect the tertiary structure of β-lactoglobulin and the structure and functional properties of soy 11S globulin. In order to explore the effect of cavitation jet treatment on the structure and emulsification characteristics of soy protein isolate, soy protein isolate solutions of different concentrations (2% and 5%) were treated with cavitation jets at different times (2, 4, 6, 8, 10 min), and the untreated soy protein isolate solution was used as a control to explore the effect of cavitation jet treatment on the structure and emulsification properties of soy protein isolate in this study. The results showed that the cavitation jet treatment for an appropriate time could reduce the sulfur-containing amino acid content, the average particle size of the solution, and the 7S subunit and A subunit content of the soy protein isolate and caused the absolute value of the ζ-potential of the protein emulsion and the increase of the interface protein content. The high and elastic modulus tended to increase, thereby significantly enchancing the protein emulsification activity and emulsification stability. The emulsification activity and emulsification stability reached the maximum value of 71.01 m2/g and 168.75 min when the 2% concentration SPI was treated by the cavitation jet for 8 min, which were 248.94% and 95.58% higher than the minimum value. At the same time, the absolute value of the zeta potential reached the maximum value of ?14.11 mV, the interface protein content reached the maximum value of 3.19 mg/m2, and the particle size was the smallest (590.5 nm). When the cavitation jet was treated with 5% concentration SPI for 10 min, the emulsification activity and emulsification stability reached the maximum, which were 52.91 m2/g and 126.97 min, respectively, 70.29% and 101.83% higher than the minimum. However, the absolute value of ζ-potential and the interface protein content had shown a downward trend. It showed that although the emulsification performance of soy protein isolate was still at a good level, it had already been processed. It could be seen that the cavitation jet treatment of two concentrations of soy protein isolate could depolymerize part of the subunits and reduce the content of sulfur-containing amino acids. At the same time, the cavitation effect expanded the protein molecules, exposed more hydrophobic amino acids, and improved its rheological properties. When the SPI concentration was 5%, all indicators were easier to reach the extreme value than when the SPI concentration is 2%. This showed that the cavitation jet physical field could adjust the emulsification activity of soy protein isolate by changing the structure and emulsion interface characteristics, which had important scientific significance for the development of new soy protein beverages, protein biogels, etc., and it was also a modification of soy protein isolate. And the application of cavitation jet physics in the food field provides the preliminary foundation.