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

Abstract

Yeasts are one of the main ingredients responsible for flavor precursors production associated with sensorial characteristics in chocolate. Using wild yeast isolated from cocoa beans fermentation is emerging as a strategy for developing starter cultures. However, the volatile compounds (VCs) produced by yeasts are not yet known. This study aimed to select wild yeasts with the potential to produce volatile compounds associated with desirable flavor attributes. A total of 150 wild yeasts strains were isolated from the spontaneous cocoa beans fermentation, of which 40 were identified by morphology and physiological features. VCs produced were identified and quantified using SPME-GC-MS and GC-FID and profiles were evaluated statistically by PCA and cluster analysis for the compounds that had a high odor threshold value. Thirty-six VCs produced by these yeasts were identified into six main families, namely esters, alcohols, acids, aldehydes, ketones, and pyrazines. PCA showed the separation of the yeasts into two main clusters. Strains, Y195 and Y246, belong to the first cluster and are the highest producers of alcohols related to floral perceptions. In the second cluster, thirty-three yeasts were grouped by their ability to produce esters. Of all of them, Y110MRS stood out for producing 2-phenyl ethyl acetate and isoamyl acetate associated with fruity perceptions. This screening allowed us to identify yeasts that produced VCs of technological interest and which could be used to develop a starter culture.

Reduction in the Cocoa Spontaneous and Starter Culture Fermentation Time Based on the Antioxidant Profile Characterization

“…The ester 2-pentanol acetate is a compound with fruity notes present in both fermentations at 48 h, which is similar to that reported by Cevallos-Cevallos et al [92]; in SC, its concentration remained relatively high until the end of fermentation compared to SF, which can be assumed that the yeast contributed to the formation of the compound (where its highest concentration was between 48 and 96 h). Regarding acids, one of the predominant compounds in SC was acetic acid (Table S4), which was similar to that reported by Chagas et al [99] and Sandoval-Lozano et al [100], which began to increase dramatically between 48 and 72 h of fermentation, a period in which it is associated with a conversion of ethanol to acetic acid, where the yeast S. cerevisiae contributes to the oxidation of alcohol [22,99,100]. A higher content of linalool could be observed in SC compared to SF, as reported by Assi-Clair et al [22]; our study showed high concentrations after 48 h of fermentation similar to Klis et al [101]; finally, a shorter presence of isobutyl acetate (48 h) was detected in SC, presenting floral, fruity and banana notes [102], as detected in the same type of fermentation in the study of Assi-Clair et al [22].…”

The contribution of fungi to the global economy

“…Other yeasts found in cocoa formation that produce aromas are Galactomyces Galactomyces geotrichus and Wickerhamomyces anomalus (Koné et al 2016). Saccharomyces, Pichia, Hanseniaspora, Kluyveromyces, Hansenula, Wickerhamomyces and Torulaspora are the predominant wild genera of yeast in cocoa fermentation in Colombia (Sandoval-Lozano et al 2022).…”

Colombian Fungal Diversity: Untapped Potential for Diverse Applications

“…The main yeast species involved in different biotechnological applications worldwide is the ascomycete fungus Saccharomyces cerevisiae. However, several native yeasts species have been demonstrated to be also involved in the production of traditional food and beverages in Colombia, such as "kumis", "chicha", and "champus", among others [14,[100][101][102].…”