Fabrication of soy protein isolate - High methoxyl pectin composite emulsions for improving the stability and bioavailability of carotenoids

A handy and efficient emulsifying emulsion was developed based on self-assembled soy protein isolate (SPI) and high methoxy pectin (HMP) for entrapping and loading carotenoids. The complex, ca. 195 nm, showed a significant improvement in solubility, emulsification (32.42 m2/g) and stability (83.86%). Moreover, the physical stability of torularhodin was remarkably improved after entrapping into the SPI-HMP complex. The retention rate for entrapped torularhodin could be up to 66.03%, 95.14% and 84.31% under treatment with ultraviolet irradiation for 8 h, thermal stock at 25 and 50 °C for 28 days, respectively. Increase of two affinities, enhancement of intermolecular hydrogen bond and hydrophobic interaction and charge changes caused by the preparation process of the complex were the main reasons for improving the properties of emulsion. At the same time, composite lotion encapsulation significantly improves the bioavailability of torularhodin, including the absorption of carotenoids in the small intestine, the content in the systemic circulation and the storage capacity in the liver. Therefore, the preparation of low price, safer, green and efficient SPI-HMP complex emulsion has long-term application prospects on the development, transportation and application of antioxidants.