Differential glucose and fructose utilization during cucumber juice fermentation

Glucose (32 mM) and fructose (36 mM) of cucumber juice were degraded simult aneously by Lactobacillus plantarum, but at different rates and extents. Gl ucose depletion was slightly more rapid than fructose during the exponentia l growth phase, but slower thereafter and stopped before exhaustion. In con trast, fructose degradation continued until all naturally present fructose was exhausted. When cucumber juice was supplemented with fructose and/or gl ucose, the starter culture continued to ferment fructose, but not glucose, resulting in an increase in lactic acid production and a decrease in termin al pH. Fructose utilization was not affected by the presence of glucose, bu t the presence of fructose reduced glucose utilization.