Yeasts as Producers of Flavor Precursors during Cocoa Bean Fermentation and Their Relevance as Starter Cultures: A Review

During the fermentation of cocoa beans, the yeasts produce volatile organic compounds (VOCs). Through reactions associated with amino acid metabolism, yeasts generate important aroma precursors as acetate esters and fatty acid ethyl esters are essential in developing fruity flavors and aromas in the final product (usually chocolate). In addition, some yeasts may have pectinolytic and antifungal activity, which is desirable in the post-harvest process of cocoa. The main yeast species in cocoa fermentation are Saccharomyces cerevisiae, Pichia kudriavzevii, and Hanseniaspora opuntiae. These produce higher alcohols and acetyl-CoA to make acetate-esters, compounds that produce floral and fruity notes. However, there are still controversies in scientific reports because some mention that there are no significant differences in the sensory characteristics of the final product. Others mention that the fermentation of cocoa by yeast has a significant influence on improving the sensory attributes of the final product. However, using yeasts as starter cultures for cocoa bean fermentation is recommended to homogenize sensory attributes such as notes and flavors in chocolate.