Interaction of lentil protein and onion skin phenolics: Effects on functional properties of proteins and in vitro gastrointestinal digestibility

The effect of protein–phenolic interactions on the functional properties of lentil protein and in vitro gastrointestinal digestibility in different systems (extract solution, protein–phenolic solution, and emulsion) was studied. The presence of phenolic compounds negatively affected the foaming and emulsion properties of lentil protein. During in vitro gastrointestinal digestion, total phenolic content (TPC) and antioxidant capacity of the samples were decreased with the presence of lentil protein at the initial phase, however, they were found to be the highest in emulsions at the intestinal phase. The amount of protocatechuic acid and phenolic acid derivative was increased at the intestinal phase, while that of other phenolic compounds was decreased. Quercetin was not detected at the intestinal phase in all systems, while its glycoside derivatives were determined, which were the highest in emulsions. Anthocyanins were also the highest in extract solution among all systems. Protein–phenolic interactions had a significant effect on functional properties of lentil proteins, and bioaccessibility or antioxidant capacity of phenolic compounds.