Phenolic compounds,
such as flavonoids, phenolic acids and tannins, could contribute greatly to the antioxidant activity of foods. Wen and Wrolstad analysed phenolic compounds in pineapple juice and found that the phenolic compounds included
sinapyl-L-cysteine, N-c-L-glutamyl-S-sinapyl-L-cysteine, Ssinapyl glutathione and a p-coumaric-like phenolic compound.