Effects of maturity stages and primary processing on total polyphenol contents and antioxidant capacities of raw cocoa powder

Abstract

In this study, influences of maturity stages, fermentation treatments and drying methods on antioxidant capacities (AC), total phenolic, proanthocyanidin, theobromine and caffeine contents of raw cocoa powder were investigated. In term of maturity stages, unfermented cocoa beans harvested from the stage one contained significantly lower total phenolic contents (TPC) (6.33 ± 0.02 g GAE/100g DM) and AC (26.82 ± 0.13 mol TE/100g DM) than those of the stage two, three and four. For unfermented samples, AC increased by increasing maturation. Meanwhile, fermentation treatments reduced AC of raw cocoa powder at late maturity stages. Cocoa fermentation using the commercial enzyme Pectinex® Ultra SP-L resulted in lower TPC but higher AC in comparison with those treated without enzymes. Prolonged fermentation from 3 to 7 days significantly reduced all analysed compounds of cocoa powder. For drying methods, in comparison with freeze dried and hot-air dried samples, sun-dried ones contained the highest phenolic compounds, proanthocyanidins, theobromine and caffeine. Two-way Anova analyses showed that changes of TPC, AC, proanthocyanidins, caffeine and theobromines of cocoa powder were strongly dependent on maturity stages, fermentation methods and fermentation duration. Keywords: antioxidant capacities, raw cocoa beans, maturity, fermentation, drying, polyphenols, alkaloids.