The health-promoting potential of peptides from brewing by-products: An up-to-date review

Substantial amounts of by-products are generated annually by the brewing industry, being currently undervalued. Nevertheless, the two major by-products (brewer's spent grain – BSG – and yeast – BSY) have potential to be converted into profitable and marketable products. Indeed, they are sources of proteins that can be hydrolysed to obtain biologically active peptides with promising application as food ingredients, supplements, or nutraceuticals due to their health-promoting properties. Moreover, the recovery of such peptides follows a sustainable and environmentally friendly principle allied with economic and social benefits. This review is an up-to-date summary of the current knowledge regarding the biological properties exerted by BSG and BSY peptides and the methodologies used to obtain those peptides. BSG and BSY hydrolysates or isolated peptides have been recognized to possess antioxidant, immunomodulatory, antihyperglycemic, antihypertensive, antithrombotic, lipid-lowering, antimicrobial, antiulcer, and antiproliferative activities, some of them proving to be multifunctional. Although more research has been conducted on BSG peptides, in vivo confirmation of bioactivities was carried out mostly for BSY, thus being more advanced for a possible translation to humans. Nevertheless, both could be commercialized as functional food ingredients, supplements, or nutraceuticals, presenting general beneficial functions, diseases risk reduction, or ameliorate pathological conditions such as non-communicable diseases, primarily cardiovascular diseases. However, further validation using animal models followed by human clinical trials needs to be carried out to translate the current findings into commercial applications, but the results collected so far indicate that such studies are justified and very promising.