INFORM June 2026

LIPID OXIDATION AND QUALITY INFORM 13

oxidation products can be responsible for unpleasant flavors. THE LIPID JOURNEY Ultimately, producers would like to reduce the lipid concentration or inhibit the lipid oxidation process in pea protein isolates. But first, it is essential to understand exactly how oxidation happens in the context of processing. “There were a few reports in the literature where researchers were connecting specific fatty acids with oxylipins and volatiles, but there were no reports on plant proteins,” says Dias. And most reports on pea oxidation had focused on the volatile secondary products. However, Dias and Oliveira wanted to include oxylipins, nonvolatile oxygenated fatty acids, in their analyses. “Ours is the first study to give a holistic snapshot of what happens with the lipid component of the pea flour when it is extracted to pea protein,” says Dias. In their recent study, Dias, Oliveira, and doctoral student Qianqian Chen analyzed pea flours and pea protein extracts for fatty acids, oxylipins, and volatile compounds. In addition to a commercial sample, the researchers analyzed flours and extracts from spring and winter pea varieties provided by the in house team at the University of Minnesota Plant Protein Innovation Center.

Pea flour (left) and spring peas (right). Source: Fernanda F.G. Dias.

Consistent with previous reports, linoleic acid, oleic acid, and palmitic acid were the main fatty acids in pea flours and pea protein isolates analyzed in the study. The total lipid concentration was higher in the protein isolates than the flours and the proportion of fatty acids that were polyunsaturated increased. Therefore, lipids accumulated and the overall fatty acid profile changed during processing. The concentrations of both free and esterified oxylipins increased after processing, except for the commercial sample in which the free oxylipin concentration remained about the same. Taking a closer look at linoleic acid-derived oxylipins, the team found that although the free oxylipin composition of the flours varied, 13-HODE was the second-most abundant in all protein isolates. This result indicates that processing favors some reactions over

Spring peas (left) and peas extract (right). Source: Fernanda F.G. Dias.

others, affecting how the final products taste. The analysis of the total oxylipin composition suggested that the lipoxygenase (LOX) enzyme was responsible for more linoleic acid oxidation than non-enzymatic mechanisms.