Production of Organic Acids

Organic acids, such as lactic acid, are used in industries including food, medicine, and biodegradable plastics.

Lactic acid is primarily produced by fermenting starch-based substrates like corn or potatoes.

These substrates are first hydrolyzed into simple sugars using amylases or dilute sulfuric acid.

The resulting sugar-rich hydrolysates are then fermented by bacteria or molds in a bioreactor.

Under anaerobic conditions, bacteria such as Lactobacillus delbrueckii produce lactic acid when supplemented with nutrients like ammonia salts, vitamins, and minerals.

Bacterial fermentation typically completes within one to two days under optimal conditions.

Alternatively, molds such as Rhizopus oryzae can ferment sugars in aerated tanks with appropriate nutrients, often completing fermentation within about two days.

As lactic acid accumulates, calcium hydroxide is added to neutralize it, increasing the pH of the medium.

This forms soluble calcium lactate, which is later isolated by concentration, filtration, or acidification during downstream processing.