Kinetics of change in colour and some bio-chemical composition during fermentation of cocoa bean
2016
Ndukwu, M.C. | Udofia, M. | Yildiz, Fatih
Fermentation and drying of cocoa bean harvested during the late season in Nigeria were studied with four different fermentation methods bordering on heap and basket fermentations. Assessment was made on the content of theobromine, caffeine,total phenol, crude protein, crude fats, carbohydrates and The L* (light–dark spectrum), a* (intensity in green and red), b* (intensity in blue- yellow), C* (chrome) and h* (hue angle) colour parameters. The maximum difference observed for theobromine caffeine and the phenolic content for all groups were 0.52, 0.24 and 0.05% respectively while crude protein, fat and carbohydrates varied by 0.78, 0.67 and 7.76%. Highest decrease in hue angle of 6.2% was recorded for Basket fermentation with the pulp regularly mixed, indicating more browning. Theoretical modeling was performed on the colour kinetics based on the first order kinetics. The experimental and the predicted value of the colour ratios showed good agreements between them with the RMSE, χ² and R² values of 1.04 × 10⁻⁴–1.22 × 10⁻³, 2.62 × 10⁻⁵–7 × 10⁻⁴ and 88.31–95.69% respectively. Drying trials were conducted in a thin layer with tempering using the oven and natural sunlight. Drying with tempering produced a first-grade cocoa bean with a pH range of 5.37–5.39.
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