Starter consortia for on-farm cocoa fermentation and their quality attributes

A starter consortium of Saccharomyces cerevisiae (Y), Lactobacillus plantarum (LAB), and Acetobacter aceti (AAB) was defined to ferment the Cocoa beans (Theobroma cacao). Emphasis was laid to optimize the microbial concentration with a functional ratio of selected cultures. A central composite rotatable design (CCRD) was employed to study the effect of inoculum size (0-20% w/v) with alcohol, titrable acidity, polyphenols, anthocyanin, cut test, and sensory as response variables. The significant (p < 0.05) response surface models with high coefficients of determination values (R²) ranging from 0.82 to 0.93 were considered for the experimental data, which represented the polynomial response models for describing the constraints. Based on the design, the concentration of consortia ranged 9.03X103 CFU/g of Y, 5.9X104 CFU/g of LAB, and 7.0X104 CFU/g of AAB. The graphical optimization of superimposed contour plots fulfilled the desired metabolites; alcohol (Y1) ≤ 11 mg/g, titrable acidity (Y2) ≥  0.25%, polyphenols (Y3) ≤ 4.0 mg/g, anthocyanin (Y4) ≤ 14 mg/g, sensory (Y5) ≥ 6.0, and cut test (Y6)≥95%. Thus, validation through a field trial was confirmed to adopt the techno-economic feasibility on-farm process with precise inoculums. The effect of starter consortia on Cocoa fermentation and quality was found to be significant.