Polyglutamic Acid in Skincare and Cosmetics
Polyglutamic acid (gamma-PGA; CAS 25513-46-6) has become one of the most talked-about humectants in skincare. It is a bio-based, biodegradable polymer produced by fermentation, and it is valued for holding a large amount of water per unit weight while leaving a light, non-tacky feel – which is why it appears in serums, creams, essences and masks.
This article looks at how polyglutamic acid is used in cosmetics and why formulators choose it. For the chemistry and specifications, see our overview of polyglutamic acid: properties, production and applications.
What Makes Gamma-PGA a Good Humectant
Gamma-PGA is a water-soluble anionic polymer with many hydrophilic (water-loving) carboxyl groups along its chain. These groups bind water strongly, giving the polymer an exceptional water-holding capacity. In a formulation this translates into:
- High water retention – it holds many times its own weight in water, giving a hydrated, plumped feel.
- Film-forming – it forms a light, breathable film that helps reduce water loss from the skin (a humectant-plus-barrier effect).
- Non-tacky feel – despite its water-binding power, it does not feel sticky, which is important for sensory acceptance.
- Compatibility – it is water-soluble and easy to incorporate into aqueous formulations.
Polyglutamic Acid vs Hyaluronic Acid
Because both are used as humectants, PGA is often compared with hyaluronic acid (HA). They are complementary rather than strictly interchangeable:
| Feature | Polyglutamic acid (gamma-PGA) | Hyaluronic acid |
|---|---|---|
| Type | Polypeptide (bio-based, biodegradable) | Polysaccharide |
| Water holding | Very high per unit weight | High |
| Feel | Light, non-tacky, film-forming | Varies with molecular weight |
| Origin | Fermentation (Bacillus) | Fermentation / animal-derived grades |
| Use | Often combined with HA in “multi-humectant” products | Widely used alone or in blends |
In practice many products use both: HA for immediate hydration and PGA for its film-forming, water-holding and light feel.
How It Is Used in Formulation
| Product type | Role of PGA |
|---|---|
| Serums and essences | Primary humectant; light, non-tacky hydration |
| Moisturisers and creams | Humectant and film former; improves skin feel |
| Masks and sheet masks | Hydrating active in leave-on formats |
| Cleansers | Helps reduce the tight, dry after-feel of cleansing |
| Sun care and after-sun | Hydration and film-forming in lightweight formats |
PGA is usually incorporated at low percentages, because its water-holding power is high and because high concentrations can raise viscosity. Molecular weight is an important specification: higher-molecular-weight grades give more film-forming and viscosity effects, lower-molecular-weight grades penetrate more readily and feel lighter.
Why “Natural and Biodegradable” Matters
Gamma-PGA is produced by microbial fermentation and is biodegradable and biocompatible. For a market increasingly focused on sustainability and “clean beauty”, that bio-based, biodegradable profile is a significant part of its appeal – alongside its performance as a humectant.
Frequently Asked Questions
What does polyglutamic acid do for skin?
It acts as a humectant, holding a large amount of water and forming a light film that helps hydrate the skin and reduce moisture loss, with a non-tacky feel.
Is polyglutamic acid better than hyaluronic acid?
Neither is simply “better” – they work differently. PGA holds a large amount of water per unit weight and gives a light, film-forming feel; HA is a well-established humectant. Many products combine both.
Is polyglutamic acid natural?
Yes – gamma-PGA is produced by microbial fermentation and is biodegradable and biocompatible, which is why it is popular in clean-beauty formulations.
At what level is polyglutamic acid used in cosmetics?
Typically at low percentages, because of its high water-holding power and its effect on viscosity. The level and molecular weight are chosen to match the desired feel and function.
Does polyglutamic acid molecular weight matter?
Yes. Higher molecular weight gives more film-forming and viscosity; lower molecular weight feels lighter and penetrates more readily, so buyers should specify the grade.
How do I buy polyglutamic acid?
PolyBlueChem supplies polyglutamic acid (CAS 25513-46-6). Contact our team for specifications, COA and a quotation.