Metabolite, volatile, and sensory profiles of cocoa and chocolate produced with Bacillus megaterium and Lactobacillus plantarum starter cultures

Abstract

Cocoa is a critical agricultural commodity enjoyed by people worldwide. The microbiome of cocoa beans has proven to be an essential influence on flavor profile, creating aromatic flavor compounds through natural fermentation. Controlled fermentation using isolated starter cultures can be employed to control the quality of the fermentation process on-farm. The relationship of the microbial community during fermentation to resultant biochemical characteristics including flavor, aroma, and metabolic attributes must be understood to be leveraged for product design. Over seven days of conventional cocoa fermentation, we identified 21 genera of bacteria, with the community demonstrating time-based differences in microbial diversity along with alterations in relation to anaerobic and aerobic fermentation conditions. We further used Lactobacillus plantarum and Bacillus megaterium as starters in controlled on-farm fermentation, which resulted in high quantities of theobromine and cyclandelate. Lactobacillus plantarum, Pichia kudriavzevii, and Bacillus megaterium were common indigenous microbes found in controlled fermentation. Volatile analysis further revealed that L. plantarum was associated with fruity–floral aroma characteristics, whereas B. megaterium contributed roasted and caramel-like flavor notes. Sensory evaluation confirmed clear discrimination among chocolate samples, with starter-fermented chocolates exhibiting pronounced fruity, floral, and honey-like attributes compared with the control.