Foundations for pH control by moisture during cocoa fermentation is revealed by genetic and stepwise regression analysis

Abstract

Physicochemical characteristics and bean composition determine the course of cocoa beans fermentation and quality. Previous studies have reported that temperature and pH are the critical physicochemical parameters to control during cocoa fermentation for homogeneous and high-quality cocoa beans in batch-to-batch chocolate manufacture, however, options for their control are not outlined for practical implementation. We investigated the physicochemical characteristics and bean composition during cocoa fermentation to assess the critical traits and dynamics of pH control, using standard methods and stepwise multiple regression analysis. The study design was factorial, comprising four genotypes and seven days of fermentation in a completely randomized layout with three replicates, using analysis of variance (ANOVA). Three parsimonious models specified from the regression analysis were represented by bean protein breakdown, bean moisture loss after fermentation, and moisture loss upon sun drying as regressands against bean pH, bean protein, and bean moisture as regressors. ANOVA revealed high genotypic variance and heritability estimates of 0.60 to 0.99 for the regressors. The models explained 75%, 77%, and 84% of the variance, respectively, and revealed that pH exerted three times more effect on protein breakdown than bean moisture and that pH control by moisture was critical in the range of pH 5.6 to 6.2 and moisture 48 to 52%. Bean protein and bean moisture are antecedents of moisture loss during sun-drying. We demonstrate, for the first time, through evidence-based research, that the moisture of the fermenting mass based on the four genotypes is the target for pH control during fermentation.