Enhancing rice protein dispersibility through pectin complexation and resulting hydrogel formation

초록

In this study, we evaluated whether complexation with pectin improves the dispersibility of rice protein (RP). RP (2 % and 5 %) was mixed with low-, medium-, and high-methoxyl pectins (LMP, MMP, and HMP, respectively) at pH 2.5 and 7. At pH 2.5, LMP markedly enhanced RP dispersibility, with dispersion beginning at 0.8 % LMP and stable gel-like structures forming at >= 2 % LMP for 2 % RP, whereas MMP and HMP caused phase separation. Notably, zeta potential shifts toward negative values indicated LMP adsorption onto the positively charged RP, and Fourier-transform infrared (FT-IR) spectroscopy showed protonation-related carbonyl changes and strengthened hydrogen bonding. Rheological measurements confirmed that only LMP-containing mixtures met hydrogel criteria (G ' > G '', tan delta < 1). In addition, scanning electron microscopy (SEM) showed a continuous network consistent with hydrogel formation. The RP-LMP hydrogels exhibited >50 % curcumin encapsulation efficiency without ethanol. Overall, LMP effectively functionalized RP under acidic conditions, forming weak but stable hydrogels suitable for delivering hydrophobic bioactive compounds.

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