Abstract
Lactobacillus casei ATCC 393 was employed as a fermentative organism to convert sugars from date juice into lactic acid. Both glucose and fructose in date juice were fermented directly without any pretreatment. The influences of supplementation of yeast extract and date juice concentration on some fermentation parameters, such as: cell growth rate, sugar conversion, productivity and yield, were investigated using this bacterium in batch fermentation. The results showed that by adding yeast extract about 20g/l in a date juice medium, the maximum specific growth rate of bacteria ([mu(m)) enhanced from 0.1229 to 0.1819 g/l. Meanwhile, increasing date juice concentration from 86.6942 to 158.9181 and 229.5367 g/l enhanced the It from 0.1819 to 0.2107 and 0.1916 g/l, respectively. It indicated that the optimum value for [mu(m) is 0.2107 g/l in this concentration range. In the date juice concentration of 158.9181 g/l, the optimum lactic acid can be produced is 117.8301 g/l with yield of 92.685% for 48 h.