Antifungal peptides from faba bean flour fermented by Levilactobacillus brevis AM7 improve the shelf-life of composite faba-wheat bread

Abstract

Faba bean is an important crop from an ecological, nutritional, and economical perspective, hence its incorporation in plant-based products can play a key role in the sustainability of the whole food system. In this study, the antifungal properties of faba bean flour were investigated employing three bioprocessing treatments including hydrolysis with a commercial proteolytic enzyme preparation, and fermentation with selected or commercial mixed sourdough starters. Faba bean flour fermented by Levilactobacillus brevis AM7 showed the broadest inhibitory spectrum against the fungal species tested and antifungal activity ranging from 25 to 73 %. Bioactive proteins and peptides were found to be responsible for the antifungal activity. Polypeptides sequences corresponding to defensin-like and non-specific lipid-transfer proteins and seven antifungal peptides having 11–22 amino acid residues and mass from 1240.7 to 2624.2 Da, were identified via Liquid Chromatography-Electrospray Ionisation-Mass Spectra/Mass Spectra (nano-LC-ESI-MS/MS). To assess the antifungal effect in food processing conditions, fermented faba bean was used as ingredient in breadmaking at a substitution level of 30 % of the dough weight. Wheat composite-bread containing faba bean sourdough, which could be claimed as “source of proteins”, according to the current EC Regulation, delayed the molds contamination, lasting up to 10 days before mold appearance, and behaving similarly to wheat bread containing calcium propionate.