Protein–lipid interactions during the incubation of whey proteins with autoxidizing lipids

The changes induced in whey proteins due to incubation with oils containing different amounts of polyunsaturated fatty acids (fish, sunflower, soybean and olive oil) and with different initial oxidation status were studied under autoxidizing conditions. Changes upon incubation with fresh vegetable oils were very limited. Only upon incubation with fish or highly oxidized soybean oil, most significant changes with respect to lysine, histidine, phenylalanine and arginine residues occurred. Remarkably, the content of methionine and tryptophan remained unchanged under the experimental conditions. The most prominent impact of incubation of whey proteins with lipids was severe protein aggregation as shown by sodium dodecyl sulphate-polyacrylamide gel electrophoresis.