3.2. pH and titratable acidityNon-g

3.2. pH and titratable acidity
Non-germinated (unprocessed) barley based food mixture had initial pH 6.02 and titratable acidity 1.69 g lactic acid/100 ml (Table 1), and on autoclaving, no significant change was noticed. However, a significant decrease in pH (4.23) and corresponding increase in titratable acidity (2.60 g lactic acid/100 ml) was observed when the autoclaved food mixture was fermented with L. acidophilus curd.

A similar trend was also observed in pH and titratable acidity of food mixtures formulated from germinated flour (Table 1). However, decrease in pH and increase in titratable acidity was significantly higher in germinated food mixtures as compared to non-germinated food mixtures. The reduction in pH may be due to hydrolysis of starch into sugars during germination, which is readily utilised by the organisms and converted to lactic acid (Sripriya et al., 1997). A slight change was observed in pH and titratable acidity of autoclaved germinated food mixture. Whereas after probiotic fermentation a significant decrease in pH and increase in titratable acidity was measured.

A rapid drop in pH with corresponding increase in titratable acidity has been reported in lactic acid fermentation of a number of foods including finger millet (Sripriya et al., 1997) and cereal-legume blend (Sindhu & Khetarpaul, 2005). The homo-fermentative L. acidophilus converts glucose to lactic acid, which is responsible for the decline in pH of the product. It was also reported that Lactobacillus spp. is more effective in lowering pH than yeast and a combination of microbes (Sangeeta & Khetarpaul, 2001).