Assessment of the yeast species composition of cocoa bean fermentations in different cocoa‐producing regions using denaturing gradient gel electrophoresis

The yeast species composition of 12 cocoa bean fermentations carried out in B razil, E cuador, I vory C oast and M alaysia was investigated culture‐independently. Denaturing gradient gel electrophoresis of 26 S rRNA gene fragments, obtained through polymerase chain reaction with universal eukaryotic primers, was carried out with two different commercial apparatus (the DC ode and CBS systems). In general, this molecular method allowed a rapid monitoring of the yeast species prevailing during fermentation. Under similar and optimal denaturing gradient gel electrophoresis conditions, the CBS system allowed a better separated band pattern than the DC ode system and an unambiguous detection of the prevailing species present in the fermentation samples. The most frequent yeast species were H anseniaspora sp., followed by P ichia kudriavzevii and S accharomyces cerevisiae , independent of the origin of the cocoa. This indicates a restricted yeast species composition of the cocoa bean fermentation process. Exceptionally, the Ivorian cocoa bean box fermentation samples showed a wider yeast species composition, with H yphopichia burtonii and M eyerozyma caribbica among the main representatives. Yeasts were not detected in the samples when the temperature inside the fermenting cocoa pulp‐bean mass reached values higher than 45 °C or under early acetic acid production conditions.