The bacteriostatic or bactericidal mechanism of sorbic acid are the same as that of potassium sorbate. When added to water, potassium sorbate dissociates into sorbic acid and potassium ions. It is the sorbic acid that is active as an antimicrobial preservative.

Like benzoic acid, sorbic acid is a lipid-soluble weak acid that:

enters into the cell of microbial through the cell membrane
then accumulates and finally influences the internal PH of microbial
eventually disrupts its transport functions and metabolic activity
result in the death of the microbial
Specification
Other names   
2,4-Hexadienoic Acid
2-propenylacrylic acid
Chemical formula    C6H8O2
CAS No.    110-44-1
Molecular weight    112.128
Boiling point    270 °C
Properties
Colorless needles or white free-flowing powder with a slight faint characteristic odor.

Structure
sorbic acid chemical structure
Image Source

Solubility
In water

Slightly soluble in water (solubility 0.16 g/100 mL at 20 °C) so it is not suitable to use it in food with much water content. Generally, it is made into salts form, potassium sorbate, which is the commonly utilized form.

In organic solvent

Soluble in ethanol, ether, propylene glycol, peanut oil, glycerin and glacial acetic acid.

PH
The antimicrobial activity of sorbic acid generates when it is in the form of a molecule, the condition of undissociated.

The PKa of sorbic acid is 4.76. That’s to say, its inhibitory activity rises as pH value (below 4.76) decreases as the percentage of the undissociated sorbic acid goes up, this leads to the enhanced antimicrobial activity.

The optimal pH for the antimicrobial activity is from 3.0 to 6.5.