Low-quality cocoa can overrule the effect of starter culture addition
Colleccíon Castro Naranjal 51 (CCN-51) cocoa finds its origin in Ecuadorian breeding experiments as a response to the cocoa crop disease paradigm. However, CCN-51 is not the best choice because of its limited flavour characteristics, although non-standardized farm practices could be part of the pitfall in fulfilling good quality outcomes with this cocoa variety. Nonetheless, an in-depth investigation of the effect of a starter culture to perform CCN-51 cocoa fermentation processes (CFPs) was not available and may bring a solution to produce cured cocoa beans of desired quality. Therefore, the present study aimed to assess the influence of the addition of functional starter culture mixtures composed of yeast strains (Saccharomyces cerevisiae IMDO 050523 and/or Pichia kudriavzevii IMDO 060005) and bacterial strains (the lactic acid bacterium strain Limosilactobacillus fermentum IMDO 0611222 and the acetic acid bacterium strain Acetobacter pasteurianus IMDO 0506386) on the microbial community and metabolite dynamics during spontaneous (two processes) and starter culture-initiated (four processes) fermentation of the cocoa pulp-bean mass in wooden boxes and drying of the cocoa beans. An amplicon sequence variant approach based on sequencing of the full-length 16S rRNA gene allowed to confirm the successful inoculation of the bacterial strains. Similarly, sequencing of the internal transcribed spacer (ITS1) region confirmed the successful inoculation of the yeast strains. Whereas the consumption of the substrates was accelerated during the SCI CFPs compared to that of the spontaneous CFPs, all CFPs also resulted in rich VOC profiles of the cocoa pulp and beans, which were represented by alcohols, aldehydes, esters, ketones, and pyrazines (solely cocoa beans). However, the effect of the CFP type faded away during cocoa curing, as no significant effect on the VOC profiles could be distinguished in the drying cocoa beans.