Biotechnological valorization of brewer's spent grains through microbial fermentation and High-Pressure Homogenization (HPH) treatments to obtain functional ingredients for food formulations

The FAO estimates that about one third of the food produced for human consumption is lost every year, with a significant proportion of it being wasted or underutilized, including cereals, fruits and vegetables. In this context, the PROACTIVE project (PRIN: PROGETTI DI RICERCA DI RILEVANTE INTERESSE NAZIONALE – Bando 2020, Prot. 2020CNRB84) aims to valorize several food by-products to obtain ingredients rich in bioactive peptides for the fortification of healthy foods. Among the biotechnological approaches, microbial fermentation with tailored strains or treatments such as High-Pressure Homogenization (HPH) could potentially improve the increase of bioactive peptides in food by-products such as brewer's spent grains (BSG). Therefore, tailored fermentations of BSG with selected yeast and lactic acid bacteria strains were performed after substrate optimization and HPH treatments (500-1000 Bar). The fermented samples were analyzed for their peptide content, and the best conditions, both the liquid supernatants and the peptide extracts were better characterized. These samples were analyzed for microbial growth and absence of cytotoxicity in the intestinal cell lines Caco-2 and HT-29 using the MTT assay. Furthermore, the protective e_ect of the samples on Caco-2 and HT-29 cells against SDS-induced inflammatory stress as well as their anti-inflammatory e_ect on macrophages (RAW264.7 cells) was investigated by measuring nitric oxide (NO) production. Overall, fermentation with yeasts and bacteria resulted in products with different peptide contents and functional properties, depending on the strain used and the HPH treatment applied. In future studies, the most promising fermented products will be used for the development of value-added foods.