Pickering emulsion gel based on WPI/SPI composite protein-sodium alginate: Encapsulation of nervonic acid and its application in processed cheese

Abstract

In this study, Pickering emulsion (PE) stabilized by whey protein isolate/soy protein isolate (WPI/SPI) composite protein particles and sodium alginate (SA) were used to construct PE gels (PEGs), which were developed as a carrier for nervonic acid (NA) and used in the manufacturing of processed cheese. At a PE/SA ratio of 5:1, the encapsulation efficiency of NA was 81.3 %. The addition of SA significantly improved the brightness (L∗), whiteness, hardness, springiness, freeze-thaw stability, and water-holding capacity of PEGs (p < 0.05). It also reduced the free sulfhydryl group content of the PEGs while increasing the total sulfhydryl and disulfide bond (S-S) content. Furthermore, SA altered the S-S conformation (from gauche-gauche-gauche to trans-gauche-trans and gauche-gauche-trans) and fluorescence spectrum, thereby modifying the tertiary structure and fluorescence intensity of the composite protein in the PEGs. Moreover, NA-loaded PEGs employed as a substitute for butter in the manufacturing of processed cheese, which made the yellow of the processed cheese lighter, the texture softer, the melting and oil precipitation decreased, the resistance to fluidity increased, the protein content increased, and the fat content decreased, while inhibits the growth and reproduction of microorganisms. These findings demonstrate that PEGs can be used as a delivery carrier for NA and have potential in the development of low-fat food substitutes.