Encapsulated Carotene Emulsion System Preparaed By Acylated Soy Protein Isolate And The Digestion In Vitro

The excellent functional properties of native SPI are usually easily interfered by external environmental factors in food processing and application.It could meet the modern human health needs to modify the structure of natural SPI by modern technology,thus improving the functional characteristics and the storage stability of SPI emulsion and the embedding efficiency of?-carotene.Through the above experimental results and analysis,the following conclusions could be drawn:(1)In this study,SPI was grafted by the acylation of ethylenediamine tetraacetic dianhydride(EDTAD).The ratio of EDTAD to SPI was 50:1000,100:1000,150:1000,200:1000,250:1000 and 300:1000 g?kg^-1,respectively.The effect of acylation on the content of carboxylic and free sulfhydryl groups,surface hydrophobicity,Zeta potential and particle size distribution of SPI were determined.It was found that the absolute value of Zeta potential and molecular weight of SPI increased significantly,which made it impossible to form effective bands in concentrated and separated gel.The results of infrared spectrum showed that the reaction between lysine with EDTAD formed more carboxyl groups on SPI.When the amount of EDTAD increased to 150 g?kg^-1,the particle size of the SPI solution decreased to 271 nm,the dispersion index PDI decreased significantly.The surface hydrophobicity,carboxyl and free sulfhydryl content were increased by 62%,115%and 214%respectively.Compared with natural SPI.The larger polymer structure of SPI continued to depolymerize and the particle size distribution of SPI particles gradually became uniform,indicating higher stability of SPI solution.(2)The influence of p H on Zeta potential,droplet size during storage was observed so as to explore the stability mechanism of potential of unmodified and acylated SPI emulsions.When p H was 6 and EDTAD was added at 150 g?kg^-1,the emulsifying activity and emulsifying stability of SPI were increased by 120%and53%respectively.The droplet size and Zeta potential of the SPI emulsion were decreased to 13?m and-50 m V respectively.When the protein concentration was4%(w/v),the emulsion stability was improved.The 21-day storage experiment showed that acylation modification greatly improved the stability of the emulsion.(3)The?-carotene-loaded emulsion system was prepared by acylated SPI,of which the storage stability and retention efficiency of?-carotene were investigated.The digestion characteristics and bioavailability of?-carotene embedded in acylated SPI emulsion were studied by constructing an in vitro simulated digestion model.The?-carotene embedded in emulsion prepared from modified SPI can be stored at room temperature(25°C)for 3 weeks with little change in emulsion potential and particle size,the retention rate of?-carotene increased.Constructing simulated digestion experiments of stomach phase and small intestine phase in vitro,it was found that less free fatty acids of acylated SPI released and?-carotene could be effectively delivered to small intestine phase through stomach phase for absorption.