Additives used to maintain or change the pH of food are called acidity regulators (also known as sour agents). In addition to imparting acidity to foods, acidity regulators also have the functions of adjusting food pH, acting as antioxidants, preventing food rancidity or browning, inhibiting the growth of microorganisms, and preventing food spoilage.

Acids can be divided into two categories according to their composition: organic acids and inorganic acids. Organic acids are mainly used as sour agents. The organic acids contained in natural foods mainly include citric acid, tartaric acid, malic acid, etc.; the acids produced by food fermentation include acetic acid and lactic acid. The most commonly used inorganic acid is phosphoric acid; the synthetic ones are fumaric acid and gluconic acid.



Common food acidity regulators



Common acidity regulators

Citric Acid

According to its water content, it is divided into monohydrate citric acid and anhydrous citric acid. It is the most used organic acid in sour agents, especially suitable for citrus beverages. Citric acid also has a chelating effect, which can remove certain harmful metals. Citric acid can prevent oxidation caused by enzyme catalysis and metal catalysis, thereby preventing quick-frozen fruits from discoloring and flavoring.



Malic Acid

Malic acid is widely present in fruits and vegetables. More than 90% of the acid in apples is malic acid. It can be used alone or together with other organic acids. It is widely used in refreshing drinks and fruit juice drinks and is also suitable for lactic acid bacteria drinks. It has a more pungent astringent taste than citric acid and has the effect of masking the aftertaste of beverages using artificial sweeteners.



Tartaric Acid

Tartaric acid is widely present in fruits, especially grapes, in free or salt form. Tartrate (tartar) can be precipitated when grape juice is stored in a cool and dark place. Tartaric acid has four configurations: d-type, I-type, dI-type, and meso-type. The naturally occurring tartaric acid is type d, and the synthetic one is type dI. Tartaric acid generally refers to d-type tartaric acid.



Lactic Acid

There are two types of lactic acid: a-type and β-type. The common method is a-type lactic acid. Colorless to light yellow transparent viscous liquid, odorless or slightly unpleasant odor. Lactic acid generally has a concentration of 85% to 95%. It is a mixture of lactic acid and anhydrous lactic acid. It can be freely mixed with water, alcohol, and ketones, and has strong hygroscopicity. Lactic acid has a strong sour taste, the acidity is about 1.2 times that of citric acid, it has a slightly astringent taste and a soft astringent taste, which is different from the sour taste of citric acid and malic acid in fruits.