Year: 2012 | Month: December | volume 1 | Issue 1
Production of organic acids, titratable acidity and pH-development during fermentation of cereal flours
Abstract: <div>Following the household method of fermentation used in making the Ethiopian</div><div>bread injera, fermentation of a flour/water slurry was carried out. The fermentation experiments were done at temperatures of 25 and 35 °C with whole grain wheat flour, whole grain tef (Eragrostis tef) flour and commercial bakery flour of 70% extraction rate. The slurry was made by mixing 300 g flour and 600 ml water. Backslopping was done by adding a portion of the slurry which was fermented in a previous batch as a starter (0.1%, 1.0%, and 10%) to the next batch to be fermented. During the fermentation, samples were taken at definite intervals of 3, 6, 9, 12, 18, 24, 48 and 84 hours respectively and kept frozen until they were used for analysis. The pH and titratable acidity were recorded and the organic acids were determined by HPLC using an Aminex® HPX-87H column, The growth of lactic acid bacteria including the typing of species/strains was also determined.</div><div>Samples of the fermenting slurry were taken for analysis and the final concentration of lactic acid was found to be approximately 1 g per 100 g. A higher amount of inoculum gave a quicker lowering of pH, and also a lower initial pH. A smaller inoculum amount showed a delayed start in the lowering of pH. A higher temperature increased the production rate of lactic acid.</div>
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