The structural and physiochemical properties of conjugated form of pea protein isolate with inulin and its influences on encapsulation of ferulic acid

The poor functional attributes of pea protein isolate (PPI) such as solubility, gelation, and emulsification limit its coating application. In this study, the PPI was conjugated with inulin and then used for encapsulation of ferulic acid. Later the conjugated form of PPI-inulin were evaluated with various experiments including degree of glycation (DG), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), foming capacity (FC), foaming permanency (FP), emultion activity index (EAI), emultion stability index (ESI), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and fluorescence spectroscopy (FS). The results of SDSPAGE, FTIR, XRD, and FP tests confirmed extensive alteration of secondary structure of PPI-inulin. Because the XRD showed the softer structure of the conjugates form of PPI-inulin compared to the crystalline structures of protein and inulin. The conjugated form of PPI-inulin enhanced FC up to 42%, FP up to 32%, EAI up to 2.8-fold (pH = 4), 1.5-fold (pH = 7), ESI up to 8.4-fold (pH = 4), and 4.8-fold (pH = 7) due to the Millard reaction between protein and polysaccharide of inulin (glycation process). The antioxidant properties of PPI-inulin (analyzed by DPPH method) increased up to 51.16%. Overall the conjugated form of PPI-inulin got very useful physiochemical properties for coating essential antioxidant of ferulic acid and various bio-actives compounds.