Integrated Assessment of Lipid Oxidation and Off‐Flavor Formation in Plant Protein Powders

ABSTRACT The widespread adoption of plant proteins is hindered by their inherent off‐flavors, often linked to lipid oxidation products. Therefore, it is essential to understand the role of lipid oxidation in flavor/off‐flavor formation. This study investigates the relationship between fatty acids (FAs), oxylipins, and volatiles in seven commercial plant protein powders, using whey protein as a reference. Linoleic acid (LA) and α‐linolenic acid (ALA) were the predominant FAs in pumpkin, pea, soy, chia, and flaxseed proteins, while oleic acid (OA) was the main FA in whey and fava bean proteins. Most samples had LA‐derived hydroxide forms as the main oxylipins in both free and esterified forms. However, in chia, keto forms were the major compounds. Importantly, the majority of oxylipins (> 80%) were found in their esterified form. Regarding secondary products, aldehydes, such as hexanal, and alcohols were the main volatiles in all samples. Principal component analysis revealed correlations between FAs, esterified oxylipins, and off‐flavor volatiles, such as LA and 9‐hydroxyoctadecadienoic acid (9‐HODE, r = 0.91, p < 0.001), 9‐HODE and hexanal ( r = 0.89, p < 0.001), and 9,12,13‐Trihydroxy‐10‐octadecenoic acid (9,12,13‐TriHOME) and 1‐nonanol ( r = 0.73, p < 0.001). These findings provide valuable insights into the role of residual lipids in off‐flavor formation in plant proteins, offering a foundation for improving their flavor quality and commercial viability.