Revalorization of beer brewing waste as an antifungal ingredient for bread biopreservation

Abstract

This study assesses the potential revalorization of beer bagasse (BB), an important food industry waste, as antifungal ingredient in bread, by lactic acid bacterial (LAB) fermentation of this food waste. Initially, in vitro studies of the metabolite and antifungal activity were performed for the preparation of a microbial culture medium for the LAB. The culture medium with a 20% BB was determined as the optimal for the bacterial growth. Therefore, bread was prepared with a 5% and 10% (w/w) of a dried powder of this fermented culture medium as ingredient. The fermentation and heat treatment during baking did not compromise the antifungal metabolites in the bread. In the trials of the augment of the shelf-life the bread with a 10% concentration of the ingredient extended the shelf life of the bread by a 1 day and 3 days against Aspergillus flavus and Penicillium commune, respectively, compared to a regular bred. When studying the mycotoxin production in the bread the addition of the ingredient at a 10% concentration resulted in an 86% reduction in aflatoxin concentration compared to the control bread. Moreover, this ingredient did not importantly deteriorate the technological parameters of the bread.