Improving the functionality of pea protein isolate through co-spray drying with emulsifying salt or disaccharide

The common method used in the food industry to manufacture pea protein isolate (PPI) is extraction by alkaline extraction-isoelectric precipitation, followed by spray drying. In this study, the effect of adding a co-spraying agent to PPI at a ratio of 10:90, trehalose (Tr), sucrose (Su) or sodium hexametaphosphate (SHMP), on the structure, functionality and aromatic profile of spray-dried PPI was studied. Results showed that the addition of Tr/Su/SHMP induced protein conformational changes in accordance to FTIR spectrum and quantification of free sulfhydryl and disulfide groups. The surface charge (zeta-potential) and surface hydrophobicity of co-spray dried PPI was also modified substantially. Such structural changes exhibited significant impacts on the functionalities of co-spray dried PPI, including solubility, water/oil binding capacity, thermal property, emulsifying capacity and stability, and foaming capacity and stability. The better foaming properties of co-spray dried PPI was also supported by measuring their ability to reduce air-water surface tension. In addition, the impact of co-spraying agent (Tr/Su/SHMP) on the aromatic profile of PPI was investigated. Twelve compounds were obtained as characteristic compounds that represent the difference among samples. Such difference was visualized by performing principal component analysis and hierarchical cluster analysis. The findings reported in this study provided structural data as the basis for facilitating the development of pea protein products with better functionalities.