Impact of Processing on Lipidomic Markers in Camelina and Pennycress Protein Isolates: A Holistic Perspective

The growing demand for plant-based products has spurred interest in novel protein sources like camelina and pennycress, which offer environmental and economic benefits. However, off-flavors in their proteins present a major challenge, limiting consumer acceptance and broader application. This study investigated the impact of protein upstream and downstream processes on total and free fatty acid composition, primary lipid oxidation products (free/esterified oxylipins), and volatile compounds formation. Camelina and pennycress full fat, defatted flour and protein isolates were evaluated. Soy defatted flour and protein isolate were used as commercial references. Fatty acid profile was analyzed using gas chromatography-flame ionization detection (GC-FID), oxylipins via liquid chromatography-tandem mass spectrometry (LC-MS/MS), and volatile compounds by headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Polyunsaturated fatty acids (PUFAs) like linoleic acid (LA) and alpha-linolenic acid (ALA) comprised 53% of fatty acids in camelina, 32% in pennycress, and 68% in soy. Protein extraction increased free LA and ALA, enhancing oxidation precursor availability. Defatting reduced free oxylipins in camelina, while protein extraction increased free oxylipins across all samples. LA-derived hydroxides and triols, including 9- and 13-hydroxyoctadecadienoic acids and 9,12,13-trihydroxyoctadecenoic acids were the main oxylipins found in the protein isolates. The majority of them were present in the esterified form. A total of 37 oxidation-derived volatile compounds were identified, including aldehydes, ketones, and alcohols, with key compounds such as hexanal and 3,5-octadien-2-one increasing during processing. A high correlation among free fatty acids, free oxylipins and off flavor components was found. This study highlights the impact of protein isolation processes on lipid oxidation markers, uncovering critical relationships between fatty acids, oxylipins, and off-flavor compounds. These findings provide insights to mitigate off-flavor formation and enhance the flavor of proteins derived from camelina and pennycress, paving the way for their broader application in plant-based products.