The Preparation And Application Of Functional Soy Protein

The purpose of this project is to remove the phytic acid in soy protein molecules andimprove protein calcium-tolerant ability, so as to improve its nutritional value for theapplication in the clinical nutrition or other functional products. This paper systematicallyinvestigated the phytase process, the combination of continuous hydrothermal treatment andultrafiltration membrane technology to remove the phytic acid of soy protein for improvingthe calcium-resistant ability of the protein. Soy proteins prepared from our method was alsoused in clinical nutrition or adolescent childhood soy milk, and the properties of theseproducts were studied. The results are as follows:Analysis of the soy protein Ca²⁺induced aggregation of7S and11S. The calcium-resistant ability of7S protein is stronger than11S protein. Under neutral conditions, thecalcium-resistant ability of7S and11S is better, and the more7S component the betterperformance. This may be concerned with the lower phytic acid content of7S protein.Phytase treatment combined with jet cooking technology was used to prepare low phyticacid resistant calcium soy protein, which was applied in clinical nutrition products. Phytasetreatment can significantly reduce the phytic acid content of soy protein under appropriateconditions, but the jet-cooking treatment has no significant effect. But the continuoushydrothermal treatment showed suppression or protection effect of soy protein on Ca2+-induced aggregation. This maybe concerned with the changes ofdepolymerization, unfoldingand exposure of the hydrophobic groups of soy protein molecules that occurs in the heattreatment process. These changes can cause a decrease in protein surface charge, therebyreducing binding interaction between the protein molecules and Ca2+. It can avoid theinteraction between11S protein and Ca²⁺, because11S protein is wrapped by7S protein. Lowphytic acid and calcium-tolerant soy protein （LPRC-SPI） was prepared by this method, itsphytic acid content decreased rate up to71%, and the resistant calcium concentrationincreased to1.1%. LPRC-SPI was used to prepare the clinical protein nutrient solutionproduct which has a good performance compared with sodium caseinate. This study canprovide the basis for the applications of LPRC-SPI in clinical nutrition.Phytase treatment and ultrafiltration membrane technologycansignificantly improve theremoval efficiency of phytic acid in the protein content. compared with the conventional SPI,the descent rate of the phytic acid content in LP-SPI can be increased to about90%; Jetcooking treatment can greatly improve the average molecular weight of the protein, thereforeultrafiltration membrane with larger MWCO can significantly increase protein retention rate and greatly reduce the phenomenon of membrane fouling.While the efficiency for thepreparation of soybean protein with low phytate content was improved. LP-SPI was used toprepare young children soymilk products, which showed good performance and stabilitycompared with ordinary isolated soy protein products. Our study will provide a reference tothe applicationof soyprotein with low phytate content and high calcium-tolerant ability in thefood industry.