Coffee fermentation: Expedition from traditional to controlled process and perspectives for industrialization

Abstract

Traditionally, harvested coffee cherries are subjected to fermentation processes during primary methods either wet, natural dry or semidry. The main function of the fermentation is to remove the outside bean layers leaving two dried seeds. A wide range of endogenous isolates was detected with pectinolytic activities including bacteria such as Klebsiella, Erwinia, Bacillus and Lactobacillus and yeasts such as Pichia, Saccharomyces, and Candida. Fermentation was also impacting coffee's sensory quality. Studies have shown that desired microbial metabolites were produced during fermentation that is believed to migrate inside coffee seeds and correlated to modulation of the final product flavor, aroma, and sensory quality. Converting spontaneous fermentation into a controlled and standardized process using starter culture and bioreactors is currently employed. This review provides a detailed explanation of these topics and mainly explores the main roles of the microflora detected during spontaneous coffee fermentation and the possible ways to convert the traditional process into a more controlled and industrialized one compromising the needs of the current extending and sustainable economy.

Keywords

• Coffee flavor
• Quality
• Starter cultures
• Mucilage degradation
• Aroma
• Bioreactors