Effect of Oil Content on Lipid and Protein Oxidation and Structural Changes During Storage of Soy‐Based Extrudates

ABSTRACT Extrusion cooking represents a promising technique for improving the nutritional and functional properties of plant proteins, making them sustainable alternatives to animal proteins. The impact of storage on lipid and protein oxidation as well as structural changes in soy‐based extrudates was examined. Soy protein isolates were mixed with 5% (SPI‐5) or 10% rapeseed and sunflower oil (1:1) (SPI‐10), extruded, and stored at 40°C for 35 days. The oil mixture was extruded as a control. Results showed increased lipid hydroperoxide levels during storage, with higher oxidation rates in bulk oil compared to SPI‐5 and SPI‐10 extrudates. Extrusion altered the secondary structure and reduced solubility, which further declined during oxidation of lipids and proteins. A positive correlation between lipid and protein oxidation highlighted the role of lipid oxidation in initiating protein oxidation. Practical applications : The findings emphasize the importance of controlling oxidative processes to preserve the nutritional value and functional properties of plant‐based extrudates. In addition, the understanding of the interplay between lipid and protein oxidation contributes to the development of plant‐based products that exhibit enhanced sensory quality and functionality. These strategies have the potential to facilitate the broader adoption of plant proteins as sustainable alternatives to animal‐derived proteins in various food applications.