The cocoa bean fermentation process: from ecosystem analysis to starter culture development

Abstract

Summary Cocoa bean fermentation is still a spontaneous curing process to facilitate drying of nongerminating cocoa beans by pulp removal as well as to stimulate colour and flavour development of fermented dry cocoa beans. As it is carried out on farm, cocoa bean fermentation is subjected to various agricultural and operational practices and hence fermented dry cocoa beans of variable quality are obtained. Spontaneous cocoa bean fermentations carried out with care for approximate four days are characterized by a succession of particular microbial activities of three groups of micro‐organisms, namely yeasts, lactic acid bacteria (LAB) and acetic acid bacteria (AAB), which results in well‐fermented fully brown cocoa beans. This has been shown through a plethora of studies, often using a multiphasic experimental approach. Selected strains of several of the prevailing microbial species have been tested in appropriate cocoa pulp simulation media to unravel their functional roles and interactions as well as in small plastic vessels containing fresh cocoa pulp‐bean mass to evaluate their capacity to dominate the cocoa bean fermentation process. Various starter cultures have been proposed for successful fermentation, encompassing both cocoa‐derived and cocoa nonspecific strains of (hybrid) yeasts, LAB and AAB, some of which have been implemented on farms successfully.

Exploring the Impacts of Postharvest Processing on the Microbiota and Metabolite Profiles during Green Coffee Bean Production

“…The results showed that the different processing conditions influenced the composition and activity of the microbial communities as well as metabolite accumulation in the endosperms. In addition, the current findings corroborate the effect of microorganisms on the chemical profiles of coffee beans and support the idea of using a starter culture during coffee processing for improved process control and prevention of spoilage and eventually steering the sensory differentiation of roasted coffee, as has been performed for cocoa bean fermentation (62,63). Further studies should ultimately allow strengthening of the understanding of the impact of the microbiota on coffee cup quality and provide robust data for the development of commercial starter cultures.…”

Microbial acidification, alcoholization, and aroma production during spontaneous lambic beer production

“…However, only two phases, the main fermentation phase and the maturation phase, characterize the lambic beer production process carried out in a common brewery, whereby AAB are only isolated sporadically. Although LAB and yeasts are predominant in lambic beers, as they are in most other naturally fermented foods and beverages, these acidic beers are thus characterized by the presence of complex microbial communities . The most prevalent and functional microorganisms during lambic beer fermentation and maturation are highlighted below in their order of appearance.…”

“…80,81 They have an optimal growth temperature between 20 and 35 ∘ C. They are Crabtree-positive yeasts, which is part of a make-accumulate-consume strategy. 68,[82][83][84] This allows them to dominate the early stages of food and beverage fermentation processes in general, because of their quick conversion of the available carbohydrates via pyruvate into ethanol through alcoholic fermentation (necessary for redox balancing or the recuperation of NAD + from NADH + H + produced during the EMP pathway) during the make-accumulate phase. Alcoholization impairs the growth of competing microorganisms by fast consumption of the substrates available and the production of high ethanol concentrations.…”

Fine Grained Longitudinal Analysis of Cocoa Bean Fermentation Provides Insights Into the Dynamics of Microbial Populations

“…Subsequently, LAB degrades the carbohydrate-rich pulp producing mainly lactic acid, finally, AAB transforms the lactic acid into acetic acid (3, 4). In this last step, the production of acetic acid lowers pH and increases bean mass temperature (40-50 °C), these conditions affect the seed and cause its death, promoting the subsequent release of the flavor precursors associated with chocolate quality (5–7). Microorganisms are also responsible for the production of volatile compounds related to aromatic flavor (e.g., alcohols, organic acids, esters, and aldehydes) and the removal of compounds associated with bitterness and astringency (e.g., like tannins, polyphenols) (1, 3, 8).…”