Impact of Grape Seed Extract on Flavor and Functionality of Pea Protein Extrudates and Patties

Consumer interest in plant-based proteins is increasing, but undesirable off-flavors from Maillard reaction and lipid oxidation processes hinder their broader acceptance. Our previous work showed that proanthocyanidin-rich plant extracts like grape seed extract (GSE) could reduce the formation of these off-flavors in aqueous plant protein solutions. This study investigated the effects of GSE addition pre- and post-extrusion at two levels (0.02% and 1.0% w/w) on off-flavor development in pea protein extrudates and patties. We hypothesized that GSE addition at different processing phases would impact its ability to alter Maillard reaction and lipid oxidation processes, thus affecting its ability to mitigate off-flavor formation. Pre-extrusion treatments reduced Maillard-associated browning products by 40% more than post-extrusion treatments, potentially due to greater protein-polyphenol interactions during extrusion-induced protein denaturation and restructuring. Conversely, post-extrusion GSE treatment decreased primary and secondary lipid oxidation products by approximately 53% and 44% in patties, respectively (vs. 15% and 31%, respectively, in pretreated samples), and enhanced antioxidant capacities across all samples. Because post-extrusion GSE treatments exhibited fewer apparent protein-polyphenol interactions, a larger proportion of polyphenols may have remained chemically available for radical scavenging. Sensory evaluation suggests that GSE did not impart astringency, a common concern with polyphenol addition. These results indicate that polyphenols may be a promising strategy for improving flavor quality in plant-based protein products. PRACTICAL APPLICATIONS: Addition of grape seed extract can help reduce off-flavors in legumes caused by major flavor degradation pathways. Adding polyphenols before processing can reduce Maillard-derived off-flavors, while polyphenols added after processing are more effective at reducing lipid oxidation-derived off-flavors. This approach offers a simple and sustainable way to enhance flavor quality and properties of plant-based meat alternatives.