Changes in the content of bioactive polyphenolic compounds of lentils by the action of exogenous enzymes. Effect on their antioxidant activity

The study of the effect of the enzymes tannase, α-galactosidase, phytase and viscozyme on the phenolic composition of lentil flours, in a semi pilot scale stirred fermentor, shows that important modifications occur. Among them, hydroxycinnamic compounds and proanthocyanidins are significantly decreased after the enzymatic treatments. However, quercetin 3-O rutinoside and luteolin increase and reach the highest concentration with tannase. The formation of trans-resveratrol was observed by the action of tannase and phytase, and gallic acid by the action of phytase, α-galactosidase and tannase. The antioxidant capacity of the methanolic extracts was determined by their free radical scavenging activity, using the DPPH test, to study the differences in the behaviour of polyphenolics compounds as antioxidants after the different enzymatic treatments. The treatments with viscozyme, α-galactosidase or tannase produce an increase in the antioxidant activity when compared to raw lentils. The results of the analysis of principal components to examine the relationship among antioxidant activity (EC50) (DPPH test) and the concentrations of polyphenolics in all lentils samples, show that the quercetin 3-O rutinoside appears to be the compound with the greatest influence on the EC50 values.