| Abstract
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Thirty-nine raw and fermented (cured) cocoa beans from different countries of origin were analysed for pH, titratable acidity, volatile acids (acetic, propionic, butyric, isobutyric and isovaleric), and nonvolatile acids (oxalic, citric, tartaric, malic, succinic and lactic). The effect of two roasting conditions, low (150 C, 20 min) and high (150 C, 30 min) on these acidic parameters was also determined. Fourteen of the bean samples were made into chocolate and were evaluated for flavor preference and characteristics. The pH of the cured cocoa beans ranged from 4.61 to 5.97, and the titratable acidity from 0.075 to 0.309 meq NaoH/g. The pH and log titratable acidity had a straight line relationship with a correlation coefficient of usd-0.94usd. Citric and lactic acids represented the two major nonvolatile acids, and acetic acid represented the major volatile acid. Cocoa beans from the Far East were significantly more acidic than those from West Africa and Central America, but were not significantly different from those of South America. High acidic beans were characterized by high concentration of acetic and lactic acids; however, the strong correlation between acetic acid with both pH and titratable acidity indicated that the acid could be responsible for the high acidity in cocoa beans. High roast significantly increased the pH, decreased the titratable acidity and the concentration of all volatile acids except acetic acid. Low roast significantly decreased the concentration of propionic and isovaleric acids. The concentration of malic acid was significantly decreased and that of butyric acid was increased; however, that of tartaric, oxalic, lactic succinic and citric acids was not affected during both roasting conditions. Chocolate samples made from Ghanian and Nigerian beans were significantly preferred by the panel members; samples from Cameroon, the Dominican Republic and Malaysia were the least preferred. There was no correlation between the flavor score and pH, titratable acidity, and both volatile and nonvolatile acids. The panel members perceived higher response of strong chocolate flavor in chocolate samples from Ghana and Nigeria as compared to other samples. Higher response of off-flavor descriptors were perceived from chocolate made from low-pH cocoa bean samples.
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