Abstract

Coffee is one of the world's most valuable, traded, and widely consumed beverages. As one of the processing steps of coffee, fermentation has gained the attention of researchers as it can be employed to improve coffee quality. The current review presents the latest knowledge regarding the application of fermentation in the coffee industry, including fermenting coffee beans to produce new materials and converting coffee by-products into value-added commodities. Fermentation using various microorganisms has been employed to diversify the production of unique food materials from green coffee beans. These products are considered superior to unfermented coffee bean foods. On the other hand, by-products of coffee processing offer an opportunity to produce microbial metabolites with applications in food. Research indicates that fermentation of coffee by-products shows excellent potential for producing value-added beverages, enzymes, organic acids, and oligosaccharides. As a result, the fermentation process of coffee beans and by-products produces valuable fermented foods with improved health benefits, such as probiotic coffee, instant coffee with low toxicants, speciality coffee, and coffee wine. Therefore, fermentation has not only improved the quality of coffee beans but has also offered a viable way to manage waste problems, aiming to create an eco-friendly environment.