MICROBIOLOGICAL, RHEOLOGICAL AND AROMATIC CHARACTERISTICS OF FERMENTED UJI (AN EAST-AFRICAN SOUR PORRIDGE)

Three methods for fermentation of uji were compared in laboratory tria ls: spontaneous, backslopping (using an inoculum from a previous ferme ntation) and use of a starter culture of lactic acid bacteria. Spontan eous fermentation resulted in the slowest decrease in pH, while the us e of starter culture led to the lowest final pH (3.5). Coliforms were eliminated in less than 8 h using backslopping or starter culture, but increased in numbers during spontaneous fermentation. The viscosity o f uji was only marginally affected by the method of fermentation. The aroma profile following spontaneous fermentation contained esters with fruity notes and ethanol and higher alcohols, while mainly organic ac ids was produced by fermentation with the starter culture. Backsloppin g led to the lowest production of almost all volatiles identified.