Genipin crosslinked sugar beet pectin-whey protein isolate/bovine serum albumin conjugates with enhanced emulsifying properties

This work aimed to construct conjugates of sugar beet pectin (SBP) with exogenous proteins by adopting a genipin (GP) crosslinking strategy. The conversion processes of two protein, bovine serum albumin (BSA) and whey protein isolate (WPI) to the molecular chains of SBP were investigated using high-performance size-exclusion chromatography technology under varying SBP/exogenous protein weight ratios (SPR) (2:1–20:1) and crosslinking times (1–25 h). When prepared at SPR 10:1, the formed SBP-WPI/BSA-SBP conjugates had notably higher molecular weights of 2151 ± 68 kg/mol and 1758 ± 45 kg/mol, respectively, in comparison with that of SBP (289 ± 16 kg/mol). In terms of reactivity, WPI showed higher reactivity than BSA in crosslinking with SBP by GP. Two representative samples, SBP-WPI-Conjugate and SBP-BSA-Conjugate, prepared at SPR 10:1 after 25 h of crosslinking were further analyzed for surface hydrophobicity (S0) and emulsifying properties. It was found that S0 values of the SBP-WPI-Conjugate and SBP-BSA-Conjugate were significantly lower than that of the control blend samples. Furthermore, the selected conjugates showed superior emulsion stabilizing properties as compared with SBP-exogenous protein blends or individual SBP and exogenous proteins. After storage at 60 °C for 7 d, emulsions stabilized by SBP-WPI-Conjugate and SBP-BSA-Conjugate at concentration of 1 g/100 g emulsion had mean droplet diameters of 0.735 ± 0.023 μm and 0.733 ± 0.011 μm at pH 3.5, and 0.972 ± 0.020 μm and 1.07 ± 0.08 μm at pH 7.0, respectively. Altogether, the work demonstrates that the GP crosslinking method is suitable for upgrading SBP to SBP-protein conjugate with enhanced emulsification properties.