Types of preservatives mainly include the following categories:
Acid preservatives: including benzoic acid, sorbic acid, propionic acid and their salts. These preservatives play an antibacterial role through undissociated molecules and usually work better under acidic conditions.
Ester preservatives: mainly refers to parabens (parabens). This type of preservative is effective in both acidic and neutral solutions, and ethyl esters and propyl or butyl esters are usually used in combination.
Biological preservatives: Currently, the only one allowed for use is nisin (a bacteriocin), which has a broad-spectrum antibacterial effect and can be used for the preservation of food and cosmetics.