Researchers have identified key factors that create the perfect chocolate flavour during the cocoa bean fermentation process. The discovery could offer chocolate producers a powerful tool to craft consistently high-quality, flavour-rich chocolate. Scientists from the University of Nottingham's School of Biosciences examined how cacao bean temperature, pH, and microbial communities interact during fermentation and how these factors shape chocolate flavour. The team identified key microbial species and metabolic traits associated with fine-flavour chocolate and found that both abiotic factors (such as temperature and pH) and biotic factors (the microbial communities) are strong,consistent indicators of flavour development. The quality and flavour of chocolate begin with the cacao bean, which is profoundly influenced by both pre- and post-harvest factors. Among these, fermentation is the first, and one of the most critical steps after harvest. It lays the foundation for aroma development, flavour complexity, and the reduction of bitterness in the final chocolate product. Dr David Gopaulchan, the first author of the paper, from the School of Biosciences explains: "Fermentation is a natural, microbe-driven process that typically takes place directly on cocoa farms, where harvested beans are piled in boxes, heaps, or baskets. In these settings, naturally occurring bacteria and fungi from the surrounding environment break down the beans, producing key chemical compounds that underpin chocolate's final taste and aroma." The researchers wanted to find out whether this unstable, natural process could be replicated and controlled in the lab. Working with Colombian farmers during the fermentation process they identified the factors that influence flavour. They were then able to use this knowledge to create a lab fermentation process and developed a defined microbial community, a curated mix of bacteria and fungi, capable of replicating the key chemical and sensory outcomes of traditional fermentations. This synthetic community successfully mimicked the dynamics of on-farm fermentations and produced chocolate with the same fine-flavour characteristics. The study has been published in Nature Microbiology.