Key Findings:
Flaxseed has a number of interesting antioxidants. This study showed that a phenolic fraction showed the highest antioxidant capacity among three flaxseed extracts. Antioxidant capacity was enhanced by both alkaline hydrolysis and simulated gastrointestinal digestion, possibly by releasing SDG and p-coumaric, caffeic, and ferulic phenolic acids. In food systems, the formation of protein−phenolic complexes may increase antioxidant capacity of plant protein concentrates. In this study, flaxseed protein−phenolic complexes acted as an antioxidant. Animal studies are needed to evaluate the bioavailability of peptides and phenolic compounds as well as to confirm the in vivo antioxidant effects.
ABSTRACT:
The impact of the naturally present phenolic compounds and/or proteins on the antioxidant capacity of flaxseed products (phenolic fraction, protein concentrates, and hydrolysates) before and after simulated gastrointestinal digestion was studied. For that, whole and phenolic reduced products were assessed. Four glycosylated phenolic compounds (secoisolariciresinol and ferulic, p-coumaric, and caffeic acids) were identified in flaxseed products. Phenolic fraction exerts the highest antioxidant capacity that increased by alkaline hydrolysis and by simulated gastrointestinal digestion. The action of Alcalase and digestive enzymes resulted in an increase of the antioxidant capacity of whole and phenolic reduced products. Principal component analysis showed that proteinaceous samples act as antioxidant is by H+ transfer, while those samples containing phenolic compounds exert their effects by both electron donation and H+ transfer mechanisms. Protein/peptide-phenolic complexation, confirmed by fluorescence spectra, exerted a positive effect on the antioxidant capacity, mainly in protein concentrates.
Link to Full Text