Enzymatic treatments of raw, germinated and fermented spelt (Triticum spelta L.) seeds improve the accessibility and antioxidant activity of their phenolics

Abstract

Our study aimed to investigate the effect of cellulase, xylanase, esterase, α-amylase and protease on the enhanced release of phenolics from spelt seeds, and to demonstrate the co-effect of enzymatic treatment, germination or fermentation on the spelt phenolics content and their in vitro and cellular antioxidant activities. Bound phenolics of spelt seeds were successfully released by different combinations of cellulase, xylanase, feruloyl esterase, α-amylase and protease. Samples treated with all five enzymes together showed significantly improved extractable p-coumaric, ferulic and p-hydroxybenzoic acid contents, particularly efficient antioxidant activity in ABTS•+ scavenging activity and the highest extractable TPCs. By combining enzymatic treatment with germination and fermentation, extractable TPCs were increased by 28% and 458%, respectively. A combination of enzymatic treatment with germination and fermentation led to enormously increased extractable trans-ferulic acid content (5899% and 8263%, respectively). The bound fraction of enzymatic treated raw seeds showed lower decrease in intracellular oxidation than the corresponding extractable fraction, but a 24-fold higher uptake of hydroxycinnamic acids. Principal component analysis showed some similarities between extractable and bound fractions of enzymatic treated raw, germinated and fermented samples, mainly due to the increase in extractable acids content (biochemical parameters), especially cis-ferulic, caffeic and p-hydroxybenzoic acids.