Production of Volatile Compounds Using Wild Yeasts in a Cocoa Leachate-Based Culture Medium

Volatile organic compounds (VOCs) play a crucial role in cocoa fermentation, shaping its final aromatic profile. The aim of this research was to identify the volatile compounds produced by wild yeasts grown in a culture medium derived from cocoa leachate. VOCs were analyzed by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry and odor activity value screening. A total of twenty-six VOCs produced by yeast strains were identified and classified into six families: alcohols, esters, aldehydes, acids, ketones, and pyrazines. Ethanol was the most abundant (355.28 mg/kg), while the total ester concentration reached 105.84 mg/kg. Principal component analysis revealed the separation of the yeast into three main clusters. Strain Y33 belonged to the first cluster, which was the highest producer of ethanol and esters associated with fruity perceptions. In the second cluster, Y29a and Y244 were the main producers of alcohols related to floral perceptions. In the third cluster, ten yeasts were grouped by their ability to produce esters. Among them, Y195 and Y110MRS stood out for producing ethyl octanoate and 3-methybutanal, compounds associated with fruit and chocolate perceptions. Overall, our findings demonstrate that cocoa leachate, the main carbon source under real fermentation conditions, can generate a VOC profile linked to desirable sensory attributes and thus represents an excellent medium for VOC production with wild yeasts while contributing to the valorization of an agro-industrial byproduct.