Exploring the impact of post-harvest processing on the microbiota and metabolite profiles during a case of green coffee bean production

The post-harvest treatment and processing of fresh coffee cherries can impact the quality of the unroasted green coffee beans. In the present case study, freshly harvested Arabica coffee cherries were processed through two different wet and dry methods, to monitor differences in the microbial community structure, as well as substrate and metabolite profiles. The changes were followed throughout the entire post-harvest processing chain, from harvest to drying, by implementing up-to-date techniques, encompassing multiple-step metagenomic DNA extraction, high-throughput sequencing and multiphasic metabolite target analysis. During wet processing, a cohort of lactic acid bacteria (i.e., Leuconostoc, Lactococcus, Lactobacillus) was the most commonly identified microbial group, along with enterobacteria and yeasts (Pichia and Starmerella). Several of the metabolites associated with lactic acid bacterial metabolism (e.g., lactic acid, acetic acid, and mannitol) produced in the mucilage were also found in the endosperm. During dry processing, acetic acid bacteria (i.e., Acetobacter, Gluconobacter) were most abundant, along with non-Pichia yeasts (Candida, and Saccharomycopsis). Accumulation of associated metabolites (e.g., gluconic acid and sugar alcohols) took place in the drying outer layers of the coffee cherries. Consequently, both wet and dry processing significantly influenced the microbial community structures and hence the composition of the final green coffee beans. This systematic approach dissecting the coffee ecosystem contributes to a deeper understanding of coffee processing and could constitute a state-of-the-art framework for the further analysis and subsequent control of this complex biotechnological process.

Jaar van publicatie:2017

Trefwoorden:Coffee bean fermentation, Dry processing, Green coffee beans, Highthroughput sequencing, Metabolite target analysis, UPLC-MS/MS, Wet processing, Bacteria/classification, Acetobacter/isolation & purification, Pichia/isolation & purification, Microbiota, Food Handling, Yeasts/isolation & purification, Mannitol/metabolism, Acetic Acid/metabolism, Coffea/microbiology, Endosperm/chemistry, Fungi/isolation & purification, Candida/isolation & purification, Enterobacteriaceae/isolation & purification, Desiccation, Fermentation, Lactobacillus/isolation & purification, Seeds/anatomy & histology, Lactic Acid/metabolism

CSS-citation score:3

Auteurs:International

Toegankelijkheid:Open