Screening Wild Yeast Isolated from Cocoa Bean Fermentation Using Volatile Compounds Profile

Area of Science:

• Food Microbiology
• Fermentation Science
• Flavor Chemistry

Background:

• Yeasts are key contributors to chocolate flavor through the production of flavor precursors.
• Wild yeasts from cocoa fermentation are a promising source for developing starter cultures.
• The specific volatile compounds (VCs) produced by these yeasts remain largely uncharacterized.

Purpose of the Study:

• To identify wild yeast strains from cocoa fermentation capable of producing VCs linked to desirable flavor attributes.
• To characterize the VCs produced by selected wild yeast strains.
• To evaluate the potential of these yeasts for use in starter culture development for chocolate production.

Main Methods:

• Isolation and identification of 150 wild yeast strains from spontaneous cocoa fermentation.
• Identification and quantification of VCs using Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry (SPME-GC-MS) and Gas Chromatography-Flame Ionization Detection (GC-FID).
• Statistical analysis including Principal Component Analysis (PCA) and cluster analysis to evaluate VC profiles.

Main Results:

• Thirty-six VCs were identified, belonging to six main chemical families: esters, alcohols, acids, aldehydes, ketones, and pyrazines.
• PCA separated yeasts into two clusters: one producing floral-associated alcohols (strains Y195, Y246) and another producing esters.
• Strain Y110MRS was highlighted for producing fruity-associated esters like 2-phenyl ethyl acetate and isoamyl acetate.

Conclusions:

• Wild yeasts possess significant potential for producing VCs that enhance chocolate flavor.
• Specific strains, such as Y110MRS, Y195, and Y246, can be selected for their ability to produce desirable flavor compounds.
• These findings support the development of novel yeast starter cultures for improved chocolate flavor profiles.