Covalent vs. non-covalent polyphenol-potato protein conjugates in emulsions: Suppressing protein-lipid co-oxidation and improving whipped cream

This study aimed to suppress lipid-protein co-oxidation in plant-based emulsions through covalent or non-covalent conjugation of resveratrol (RES) or luteolin (LUT) with potato protein isolate (PPI), and to develop functional whipped cream alternatives. Covalent conjugates (C-LUT/C-RES) showed higher polyphenol grafting efficiency non-covalent systems. The presence of a catechol group in LUT likely facilitated polyphenol grafting rate and enhanced radical scavenging, resulting in C-LUT emulsions exhibiting 26% lower TBARS (16.07 mg MDA/kg) and 44.18% less protein carbonyl formation after 15 days, superior to C-RES and unmodified PPI. C-RES demonstrated greater protection against protein oxidation, highlighting structure-function differences. C-LUT emulsions displayed improved rheology (higher viscosity and G′) and, when formulated into whipped cream, reduced whipping time to 27.33 s (vs. 240.33 s for Milk), increased hardness by 33.3%, chewiness by 12.6-fold, and springiness by 17.64%, while reducing leakage by 3.01%. In vitro digestion revealed 16.48% lower free fatty acid release and smaller particle size (1.28 μm, 65.6% of PPI), indicating delayed lipid hydrolysis. These findings demonstrate that C-LUT synergistically enhances oxidative stability, textural performance, and nutritional modulation, offering a promising strategy for engineering plant proteins in next-generation dairy alternatives.