Bioprocessing of Brewers' Spent Grain Enhances Its Antioxidant Activity: Characterization of Phenolic Compounds and Bioactive Peptides

Michela Verni; Erica Pontonio; Annika Krona; Sera Jacob; Daniela Pinto; Fabio Rinaldi; Vito Verardo; Elixabet Díaz-de-Cerio; Rossana Coda; Carlo Giuseppe Rizzello

doi:10.3389/fmicb.2020.01831

Bioprocessing of Brewers' Spent Grain Enhances Its Antioxidant Activity: Characterization of Phenolic Compounds and Bioactive Peptides

Front Microbiol. 2020 Jul 31:11:1831. doi: 10.3389/fmicb.2020.01831. eCollection 2020.

Authors

Affiliations

¹ Department of Soil, Plant and Food Science, University of Bari Aldo Moro, Bari, Italy.
² Research Institute of Sweden, Gothenburg, Sweden.
³ Giuliani S.p.A., Milan, Italy.
⁴ Department of Nutrition and Food Science, University of Granada, Granada, Spain.
⁵ Institute of Nutrition and Food Technology "José Mataix", Biomedical Research Centre, University of Granada, Granada, Spain.
⁶ Department of Food and Nutrition Sciences, University of Helsinki, Helsinki, Finland.
⁷ Helsinki Institute of Sustainability Science, Helsinki, Finland.

Abstract

Brewers' spent grain (BSG) is the major by-product of the brewing industry which remain largely unutilized despite its nutritional quality. In this study, the effects of fermentation on BSG antioxidant potential were analyzed. A biotechnological protocol including the use of xylanase followed by fermentation with Lactiplantibacillus plantarum (Lactobacillus plantarum) PU1, PRO17, and H46 was used. Bioprocessed BSG exhibited enhanced antioxidant potential, characterized by high radical scavenging activity, long-term inhibition of linoleic acid oxidation and protective effect toward oxidative stress on human keratinocytes NCTC 2544. Immunolabelling and confocal laser microscopy showed that xylanase caused an extensive cell wall arabinoxylan disruption, contributing to the release of bound phenols molecules, thus available to further conversion through lactic acid bacteria metabolism. To clarify the role of fermentation on the antioxidant BSG potential, phenols were selectively extracted and characterized through HPLC-MS techniques. Novel antioxidant peptides were purified and identified in the most active bioprocessed BSG.

Keywords: antioxidant activity; bioactive peptides; bioprocessing; brewers’ spent grain; phenolic compounds.