Biochemical Changes during Alcoholic Fermentation in the Production of ``Tchapalo'', a Traditional Sorghum Beer

The production of tchapalo remains more or less an empirical process. For the improvement of the product quality, there is a need of more knowledge on this traditional process and the beer characteristics. The alcoholic fermentation is one of the most steps which most determines the quality of the beer. In this study, the characteristics of the traditional starter and the evolution of temperature, ethanol, sugars and organic acids were assessed at small-scale production during alcoholic fermentation of tchapalo. Brewers used traditional starter at the rate of 0.76-0.88 % when it was dried or at 2.38 % when it was not. When the wort was at 36.6-39.3 °C, the starter was added to initiate the fermentation. Temperature decreased to 34.6-36.5 °C at the end of the fermentation which was concluded after 7.6 h to 8.4 h. Sugars were consumed during the fermentation but it remained 12.9 to 16.57 g/L of reducing sugars and 8.02 to 9.12 °Brix of TSS in the final product. Ethanol content increased from 0.02-0.35 % (v/v) in the wort to 3.5-4.59 % in the beer. The oxalic, citric, tartaric, malic, lactic, fumaric and propionic acids were found in the wort and in tchapalo and increased or decreased during fermentation differently from one site to another. But, the acetic acid was not always detected in both the wort and the beer.