Utilization of canned pineapple syrup for lactic acid production

Canned pineapple syrup was utilized for lactic acid production. The syrup contained glucose, fructose and sucrose, converted to lactic acid. Sucrose was not readily metabolized by lactic acid bacteria and remained in medium after up to 32 h of cultivation This problem was probably caused by catabolite repression by glucose and fructose. To hydrolyze sucrose into glucose and fructose, commercially available yeast invertase was used. Lactic acid production was successfully completed within 10 h when the yeast invertase was added to the medium. No catabolite repression was observed. For more effective utilization of canned pineapple syrup for lactic acid production, grape invertase was used, which was recovered from the grape waste in wine production. While the optimum pH for grape invertase and the lactic acid bacterium are different, effective production of lactic acid could be carried out by the control of pH from 6.5 to 5.0. Combining waste streams such as this process can be applied for production of other useful material.