How to use Propylene Glycol in Formulation

How to use Propylene Glycol in Formulation
March 2, 2020 Aidee Erhime
Propylene Glycol

What is Propylene Glycol

Propylene glycol is a non-naturally occurring colorless and odorless liquid that has a wide variety of applications in formulation of some foods and cosmetic products. It is a viscous fluid that is highly soluble in water and very hygroscopic.

Ingredient Chemistry

This compound has two alcohol groups and is miscible with a broad range of solvents including water. It does not occur naturally in nature and in some large industries, it is used as antifreeze at specific percentages.

IUPAC name:

Propane–1,2–diol.

Melting Point:

-590C

Density:

1.04g/cm3

Boiling Point:

188.20C

pH:

6-8

Flash point:

2250F

Molecular Formula: 

C3H8O2

Molecular Weight: 

76.10

Physical properties

– Water soluble

– Easily metabolized

– Viscous liquid (lighter than vegetable glycerin).

In formulation

Contrary to some opinions, propylene glycol is not a toxic compound when handled properly. In cosmetics formulation,

  • It is primarily used as a solvent because of its ability to dissolve quite a number of substances.
  • Its antimicrobial function works same as glycerin and this is why it is sometimes used in addition to a preservative.
  • Its humectant property helps prevent loss of water in the products.
  • It increases skin permeability of active ingredients as it penetrates into the outermost skin layers

How to Use

Propylene glycol is typically added to the water phase of the formulas at approximate percentages of 1-5%.

According to the FDA (2019), “the ingredient is used in foods at levels not to exceed current good manufacturing practice. Current good manufacturing practice results in maximum levels, as served, of 5 percent for alcoholic beverages; 24 percent for confections and frostings; 2.5 percent for frozen dairy products; 97 percent for seasonings and flavorings; and 5 percent for nuts and nut products.”

“Propylene glycol is typically added to the water phase of the formulas at approximate percentages of 1-5%”.

 

Health Risk

Certain people are of the opinion that using propylene glycol in formulation, poses health risks and as such, should be avoided. Reasons cited include that this compound is a major component of hydraulic fluids and is therefore dangerous to the skin.

The truth to this claim is simple, when this compound is mishandled and used in higher than recommended concentrations, sensitivities may occur. This is also true for all other compounds that exist on earth.

The importance of propylene glycol in cosmetics formulation is simply to keep the product from reacting to extreme temperatures (cold and heat). Think about it, if it can be used in food that you eat, what makes it bad to use in cosmetics products?

 

 

Further Read:

International Journal of Toxicology, Supplement, September-October 2012, pages 245S-260S

Critical Reviews in Toxicology, April 2013, issue 4, pages 363-390

Skin Pharmacology and Applied Physiology, Volume 14, 2001, pages 72-81

 

 

 

 

 

 

 

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