Microencapsulation Properties Of Soy Protein Isolate

In this paper, powdered emulsions of soy protein isolate (SPI) and soya oil were preparedby homogenization and spray drying. Microencapsulation efficiency (ME), redispersibility inwater and morphology of the powders were determined to reveal microencapsulationproperties of SPI. Storage stability of powders in humid atmosphere was also evaluated toobtain more understanding of microencapsulation properties of SPI. This work was carriedout not only for broadening the scope of application of SPI, but also for developing low-costmicrocapsule products suitible for microencapsulated fat-soluble active substances. The mainresults are as follows:1. Properties of spray-dried powders greatly depend on the stability of initial emulsions.The ME of SPI without any treatment used as wall material alone was only47.8%.Preheating could significantly improve emulsifying ability of protein, which lead to greatincrease in ME, which was77.3%. Powders were made by SPI with lactose had much higherME (90.8%) and well redispersibility in water. Preheating and SPI/lactose blending treatmenttogether could obtain best ME of98.7%. Preheating produced little difference in storagestability of powders, but addition with lactose would largely weaken its stability.2. There were many processing parameters had effect on microencapsulation propertiesof SPI and storage stability of spray-dried powders. Results showed that good ME,redispersibility and storage stability of microencapsulates were obtained when core/wall ratiowas less than1:1, high pressure homogenization (80MPa) and suitable solid content (15%,w/w) could improve microencapsulation effect, while inlet temperature affectedinsignificantly.3. To further explore the effect of glycosylation modification on microencapsulationproperties of SPI-lactose and storage stability of spray-dried powders, the research werecarried out and results showed that7.5-13.6%glycosylation modification improvedemulsifying ability of SPI and further improved microencapsulation properties of spray-driedemulsions. Extractable oil of all powders were lower than1.5%and powders had excellentredispersibilty, but there was insignificant difference between microencapsulate systems ofglycosylated SPI with degree of graft from7.5%to13.6%. Humid atmosphere had great impact on powders obtained by glycosylated SPI and the mechanism still needs to study.