Microbial alchemy: upcycling of brewery spent grains into high-value products through fermentation

Abstract

Spent grains are one of the lignocellulosic biomasses available in abundance, discarded by breweries as waste. The brewing process generates around 25–30% of waste in different forms and spent grains alone account for 80–85% of that waste, resulting in a significant global waste volume. Despite containing essential nutrients, i.e., carbohydrates, fibers, proteins, fatty acids, lipids, minerals, and vitamins, efficient and economically viable valorization of these grains is lacking. Microbial fermentation enables the valorization of spent grain biomass into numerous commercially valuable products used in energy, food, healthcare, and biomaterials. However, the process still needs more investigation to overcome challenges, such as transportation, cost-effective pretreatment, and fermentation strategy. to lower the product cost and to achieve market feasibility and customer affordability. This review summarizes the potential of spent grains valorization via microbial fermentation and associated challenges.

GRAPHICAL ABSTRACT

Keywords:

• Brewer’s spent grains
• microbial fermentation
• pretreatment
• valorization
• energy
• biopolymer

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was supported by the National Research Foundation of Korea (NRF), the Ministry of Science and ICT (NRF-2022R1A2C2003138, NRF-2022M3I3A1082545) and the R&D Program of MOTIE/KEIT (Grant No. 20009508 and 20014350).