What are some trivia points about acidity regulators?

The role of acidity regulators and their classification

Additives used to maintain or change the pH of food are called acidity regulators (also known as acidulants). In addition to giving food a sour flavor, acidity regulators also regulate the pH of food, act as antioxidant synergists, prevent food rancidity or browning, inhibit the growth of microorganisms, and prevent food spoilage.
Acids can be divided into two categories according to their composition: organic acids and inorganic acids. Organic acids are mainly used as acidulants. Organic acids contained in natural foods include citric acid, tartaric acid, malic acid, etc. Acetic acid and lactic acid are produced by food fermentation. The more used inorganic acid is phosphoric acid; synthetic ones are fumaric acid and gluconic acid.
Relationship between the strength of acidity of food and PH
Overall, the strength of a food’s acidic flavor is basically proportional to its total acid content, and therefore related to some extent to pH.
Generally speaking, the pH of most foods is between 5 and 6.5, which is acidic but not acidic. The acidity threshold for inorganic acids in foods is between 3.4-3.5, and for organic acids between 3.7-4.9. If the pH is below 3.0, the acidic flavor is too strong and more difficult to tolerate. In addition, different types of acids present a very different sour flavor in the mouth.
For example, if the same solution has a pH of 4.5, one is a buffered solution, and the other is adjusted with an acid, there may be a big difference in the acidic flavor in the mouth between them. The solution adjusted with acid has more free hydrogen ions and has a stronger instantaneous sour taste, while the buffered solution releases hydrogen ions in the mouth as saliva dilutes it and the sour taste is more persistent.
In addition, acidity regulators also include more than just acids, but also some alkalis that maintain alkalinity and salts that have a buffering effect, and the flavors of these substances are much more complex and difficult to compare.
Common acidity regulators
3.1 Citric acid, also known as citric acid, is categorized into citric acid monohydrate and citric acid anhydrous depending on its water content. It is the most used organic acid in acidulants and is particularly suitable for citrus beverages. Citric acid also has a chelating effect and is able to remove certain harmful metals. Citric acid can prevent oxidation caused by enzyme catalysis and metal catalysis, thus preventing frozen fruits from changing color and taste.
3.2 Malic acid Malic acid is widely found in fruits and vegetables, and more than 90% of the acid in apples is malic acid. It can be used alone or at the same time 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 stimulating astringent flavor than citric acid, and has the effect of masking the aftertaste of beverages that use artificial sweeteners.
3.3 Tartaric Acid Tartaric acid is widely found in fruits, especially grapes, in free or salt form. Grape juice precipitates tartaric acid salts (tartaric) when stored in a cold dark place. Tartaric acid has four configurations: d-type, I-type, dI-type and meso (endocyclic). Naturally occurring tartaric acid is of the d-type and synthetic tartaric acid is of the dI-type. General tartaric acid is d-type tartaric acid.
3.4 Lactic Acid Lactic acid is divided into two types: a-type and β-type, and a-type lactic acid is produced by common methods. It is a colorless to light yellow transparent viscous liquid, odorless or slightly unpleasant odor. The general concentration of lactic acid is 85%~95%, it is the mixture of lactic acid and anhydrous lactic acid, it can mix freely with water, alcohol and ketone, and it has strong hygroscopicity. Lactic acid has a strong sour taste, acidity is about 1.2 times that of citric acid, slightly astringent, with a soft astringent flavor, different from the sour taste of citric acid and malic acid in fruits.