Parameters affecting the quality of processed cocoa powder: Acidity fraction

Total, free and fixed, volatile and non-volatile acids, as well as lactic and phosphoric acid contents were determined in six samples of three batches of cocoa beans subjected to various stages of fermentation (1-6 days), in 37 samples of non-alkalinized low-fat cocoa powder and in 15 samples of instant cocoa powder. The physico-chemical data obtained were related to sensory evaluation and submitted to analysis of variance, multivariate distribution (Mahalanobis distance) and the Pearson Chi-squared test. From the results obtained we can infer that optimally fermented cocoa samples should have a maximum total fixed acidity of 39 mEq NaOH/100 g, a non-volatile fixed acidity of 35 mEq NaOH/100 g, and a lactic acid content of 0.50 g/100 g (5.5 mEq/100 g). No correlation was found to occur between other acidities, the phosphoric acid content, and sensory data. These parameters are related to the sensory properties of cocoa and can be used to confirm deficiencies.