THE UTILIZATION OF BEET MOLASSES IN CITRIC-ACID PRODUCTION WITH YEAST

Citric acid, widely used as an additive in the food industry, was produced in a batch cultivation process with Yarrowia lipolytica yeast on inverted beet molasses derived as a byproduct of the sugar industry. Glucose and inverted sucrose were used as substrate for comparison. The citric acid production appeared to be growth associated on molasses but began first at the end of the exponential growth phase on pure glucose. On molasses, the citric acid concentration of 54 g/l was 86% of the total of citric and isocitric acids. Both on glucose and on sucrose the highest citric acid concentration reached was 87 g/l. The actual total acid yield coefficient increased during the cultivation. The adaptation to glucose or fructose had no significant effect on the citric acid production. The cell growth doubled on inverted molasses as compared with inverted sucrose, resulting partly in a decrease of about 30% in the maximum product concentration. The citric acid production was 0.91 g/g per consumed glucose and 0.77 g/g per consumed fructose from the inverted sugar beet molasses.