INFORM June 2026

14 INFORM JUNE 2026 , VOL. 37, NO. 6

“The free oxylipins are the most reactive, but the esterified compounds are not usually analyzed,” says Dias. “We see a lot of oxidation in the esterified oxylipins as well.” Other lipid researchers have emphasized that both free and esterified should be analyzed due to their contribution to the off-flavor formation. Off-flavor volatile compounds did increase after processing, mostly due to secondary products of lipid oxidation. One of the most abundant in the protein isolates was hexanal, an aldehyde with a beany odor. The ketone 2-heptanone, responsible for herbal flavors, increased in all protein isolates compared to flours. The winter pea sample generally had lower levels of volatile compounds compared to the other samples, so this variety could be useful for producing peas with less beany, earthy flavor. Principal components analysis, Pearson’s correlation analysis, and linear correlation analysis together supported the hypothesis that processing leads to the accumulation of off-flavor compounds via lipid oxidation of PUFA. Oxidation then results in oxylipins such as 13-HODE and volatiles such as hexanal. “We could actually name the specific oxylipins being formed from linoleic acid and infer whether this was lipoxygenase-catalyzed or not,” says Dias. “This

information now allows us to trace where compounds are going.” STRATEGIES TO REDUCE OFF-FLAVORS Processors could monitor oxylipin formation as proteins are isolated, and these data could tell them when oxidation is getting out of hand. “The concentration of oxylipins give you an early warning that oxidation is occurring,” says Oliveira. “This information can help you choose better processes or better pea varieties or help predict shelf life.” Christian Trindler, lecturer at Bern University of Applied Sciences HAFL School of Agricultural, Forest, and Food Sciences in Switzerland, also has studied pea protein extraction. “The paper was quite impressive—Dias’s group showed that protein extraction also enriches the fats and a lot of volatiles,” he says. “They conclude it is highly correlated, but the big question remains: How do you get rid of the off-flavor compounds?” Breeding new varieties of pea could help—peas with even less aroma, a higher protein concentration, or less LOX activity could produce a protein extract with less off flavor compounds. However, breeding programs can be challenging. “We looked for new breeds here in Switzerland that already had low aroma while

being heat resistant because nowadays it is getting hotter and drier,” Trindler says. However, he says the project failed. It was difficult to correlate GC-MS data with aromas. “GC-MS does not tell you if the aroma is still there— you have to taste it and do a sensory analysis, which is expensive to do in a scientific way,” he says. Mehdi Abdollahi, associate professor in the Division of Food and Nutrition Science at Chalmers University of Technology in Sweden, has studied pea protein processing, as well as pre milling initiatives. “There is potential to mitigating both off-flavors and nutritionally unwanted compounds by optimizing the farming and harvesting step,” he says. “If you optimize those, you start with a much cleaner biomass.” As part of the 100%Pea project, Abdollahi’s group conducted a study to see how harvest location and cultivation year influence the volatile and other off-flavor compounds in pea protein extracts. Cultivation location had a large impact on the fatty acid composition in seeds and protein extracts, resulting in varying concentrations of linoleic and α -linolenic acid, the main PUFAs that undergo lipid oxidation. Volatile compounds, including hexanal, were highly concentrated in protein isolates, and harvest location and year influenced their concentration in the isolates.