New research ferments the perfect recipe for fine chocolate flavour

Key elements that affect chocolate’s flavour during the fermentation of cocoa beans have been discovered by researchers; this information may provide chocolate manufacturers with a useful tool to consistently produce high-quality, flavourful chocolate.

Researchers from the School of Biosciences at the University of Nottingham studied how the temperature, pH, and microbial populations of cacao beans interact during fermentation to influence the flavour of chocolate.

The scientists discovered that both biotic (the microbial communities) and abiotic (temperature and pH) elements are powerful, reliable predictors of flavour development. They also identified important microbial species and metabolic characteristics linked to fine-flavour chocolate. The study was published in the journal Nature Microbiology.

Dr David Gopaulchan, the first author of the paper, from the School of Biosciences notes that 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,” he observes. “However, this spontaneous fermentation is largely uncontrolled. Farmers have little influence over which microbes dominate or how the fermentation process unfolds. As a result, fermentation, and thus the flavour and quality of the beans, varies widely between harvests, farms, regions, and countries.”

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.

Dr David Gopaulchan adds: “The discoveries we have made are really important for helping chocolate producers to be able to consistently maximise their cocoa crops as we have shown they can rely on measurable markers such as specific pH, temperature, and microbial dynamics, to reliably predict and achieve consistent flavour outcomes.”