What is the production method of anhydrous citric acid?

1. Fruit extraction method: Citric acid can be extracted from fruits with high citric acid content such as lemons, oranges, tangerines, and apples. However, this method has high cost and is not conducive to industrial production.

2. Chemical synthesis method: The raw materials include acetone, dichloroacetone or ketene. Due to the complex process, high cost and low safety of chemical synthesis method, it is rarely used.

3. Biological fermentation method: including surface fermentation method, solid surface fermentation method, deep fermentation method, and petroleum hydrocarbon fermentation method. Among them, the deep fermentation cycle is short, the yield is high, it saves labor, it occupies a small area, and it is easy to realize instrument control and continuity. Therefore, at present, molasses (beet molasses, sugarcane molasses, etc.) and starchy raw materials (cassava, corn, etc.) are used as raw materials, Aspergillus niger is used as the fermentation strain, and citric acid is produced by deep fermentation, with the output accounting for about 80%.