Harnessing agrifood by-products for sustainable protein development: a focus on circular economy and agriculture

The food industry generates substantial amounts of food losses and waste, contributing significantly to environmental impacts. In response, industries are exploring innovative strategies to valorise these by-products, recognizing their potential as a source of diverse compounds with economic value. Among these by-products, spent brewer's yeast (SBY) stands out as a significant residue from the brewing process, boasting a valuable nutritional composition rich in proteins and carbohydrates. This makes it a promising candidate for applications as a food ingredient, aligning with the goals of sustainability, healthy lifestyles, and circular economy principles. This study focuses on transforming SBY into a high-value product suitable for incorporation into protein-enriched food formulations. The investigation involves the compositional analysis of the SBY and explores the production of new fractions combining an autolysis process (70ºC, 5h) with fractionation by membrane filtration to obtain functional fractions. Size exclusion high- performance liquid chromatography (SE-HPLC) analysis performed on the obtained fractions showed a chromatography profile with high diversity in the molecular size distribution. The obtained fractions were dried to assess the bioactivities: antioxidant (ORAC and ABTS) and antimicrobial (minimal inhibitory concentration). The results demonstrate the successful production of a high-protein food ingredient from SBY, positioning it as a promising ingredient for formulating various protein-enriched foods, including bakery and dairy products. This study underscores the potential of utilizing by-products to create value-added ingredients, contributing to the sustainability and circular economy goals within the food industry.