First description of bacterial and fungal communities in Colombian coffee beans fermentation analysed using Illumina-based amplicon sequencing.

In Colombia, coffee growers use a traditional method of fermentation to remove the cherry pulp surrounding the beans. This process has a great influence on sensory quality and prestige of Colombian coffee in international markets, but has never been studied. Here we use an Illumina-based amplicon sequencing to investigate bacterial and fungal communities associated with spontaneous coffee-bean fermentation in Colombia. Microbial-derived metabolites were further analysed by high-performance liquid chromatography and gas chromatography-mass spectrometry. Highly diverse bacterial groups, comprising 160 genera belonging to 10 phyla, were found. Lactic acid bacteria (LAB), mainly represented by the genera Leuconostoc and Lactobacillus, showed relative prevalence over 60% at all sampling times. The structure of the fungal community was more homogeneous, with Pichia nakasei dominating throughout the fermentation process. Lactic acid and acetaldehyde were the major end-metabolites produced by LAB and Pichia, respectively. In addition, 20 volatile compounds were produced, comprising alcohols, organic acids, aldehydes, esters, terpenes, phenols, and hydrocarbons. Interestingly, 56 microbial genera, associated with native soil, seawater, plants, insects, and human contact, were detected for the first time in coffee fermentation. These microbial groups harbour a remarkable phenotypic diversity and may impart flavours that yield clues to the terroir of Colombian coffees.

Biotechnological approaches for cocoa waste management: A review.

Cocoa beans provide raw materials for global food industries valued in excess of $47 billion in world exportations. Through on-farm processing, about 80% of cocoa fruit is discarded as residual biomass, including cocoa pod husks, cocoa bean shells and cocoa sweatings. Farmers routinely discard these residues/by-products during the initial cocoa bean processing steps, occupying vast areas and raising social and environmental concerns. Alternatively, this residual biomass is used as cocoa tree fertilizer. However, its disposal is performed without proper treatment, resulting in putrid odors and plant diseases. Recently, some studies have reported the use of cocoa by-products in the production of high-value-adding molecules with potential applications in the food, pharmaceutical and cosmetic industries. In this aspect, biotechnological approaches have been shown to be a viable alternative for the transformation of this residual biomass into fine products. This article reviews the biotechnological approaches implemented for the management and exploitation of cocoa by-product. Related topics on cocoa production and residual biomass generation, sustainability and valorization of cocoa chain are addressed and discussed.

Exploring the impacts of postharvest processing on the aroma formation of coffee beans - A review.

The aim of this review is to describe the volatile aroma compounds of green coffee beans and evaluate sources of variation in the formation and development of coffee aroma through postharvest processing. The findings of this survey showed that the volatile constituents of green coffee beans (e.g., alcohols, aldehydes, and alkanes) have no significant influence on the final coffee aroma composition, as only a few such compounds remain in the beans after roasting. On the other hand, microbial-derived, odor-active compounds produced during removal of the fruit mucilage layer, including esters, higher alcohols, aldehydes, and ketones, can be detected in the final coffee product. Many postharvest processing including drying and storage processes could influence the levels of coffee aroma compositions, which remain to be elucidated. Better understanding of the effect of these processes on coffee aroma composition would assist coffee producers in the optimal selection of postharvest parameters that favor the consistent production of flavorful coffee beans.