How to judge the end point of citric acid production by Aspergillus Niger fermentation

1. Observing the change of pH value, the pH value of citric acid is about 2.2-2.5. When the pH value of the fermentation broth is close to this value, it means that the output of citric acid has reached saturation and the fermentation process is coming to an end.

2. Observe the output of citric acid, and regularly take samples to detect the content of citric acid. When the output of citric acid no longer increases or slowly increases, the fermentation approaches the end point.

3. Observe the change of oxygen utilization rate. Aspergillus Niger fermentation needs oxygen as respiratory substrate. When the oxygen utilization rate decreases or stops, the fermentation approaches the end point.