Sorbic Acid

Sorbic acid is antimicrobial agents often used as preservatives in food and cosmetics to prevent the growth of mold, yeast, and fungi. In general the sorbic acid salts are preferred over the acid form because they are more soluble in water, but the active form is the acid. The optimal pH for the antimicrobial activity is below pH 6.5. Sorbates are generally used at concentrations of 0.025% to 0.10%. Adding sorbate salts to food will, however, raise the pH of the food slightly so the pH may need to be adjusted to assure safety. Typical concentration 0.05-0.3% (if used alone) or 0.05-0.15% (if used in combination with other preservatives). Under certain conditions, sorbic acid may oxidize and cause slight color changes in the cosmetic product. This can normally be prevented by adding 0.1–0.3% citric acid to the product. For external use only. All kinds of cosmetic products like creams, lotions, shampoos, makeup & sunscreen products. Sorbic acid is sparingly soluble in water but dissolves well in alcohol and alkaline solutions. Here are different ways to dissolve it based on your needs:

1. Dissolving in Water (Limited Solubility)

• Sorbic acid has a low solubility in water (0.16 g per 100 mL at 20°C).

• To improve solubility:

• Use warm water (not boiling).

• Stir continuously.

• Use a small amount of ethanol or propylene glycol as a co-solvent.

2. Dissolving in Alcohol (Better Solubility)

• Sorbic acid dissolves well in ethanol, propylene glycol, or glycerin.

• Recommended: Dissolve in alcohol first, then mix into water-based solutions.

3. Dissolving in Alkaline Solution (Best for Preservative Use)

• Sorbic acid converts into potassium sorbate when mixed with a mild base (like potassium hydroxide or sodium bicarbonate).

• Method:

1. Dissolve sorbic acid in a small amount of water.

2. Add potassium hydroxide (KOH) or sodium bicarbonate until fully dissolved.

3. Adjust pH to around 4.5–6.5 for preservation use.

Best Method Based on Application

• Cosmetic & Skincare Formulations → Dissolve in ethanol or propylene glycol.

• Food Preservative (Potassium Sorbate) → Dissolve in a mild alkaline solution.

• Beverages → Pre-dissolve in alcohol before mixing into liquids.