What is Polyglutamic Acid?
Polyglutamic acid, or “PGA”, is a naturally occurring, non-toxic polymer of the non-essential amino acid glutamic acid. Known by its gamma form (γ-PGA), this highly versatile ingredient has a long history of human use. It occurs naturally in natto, a traditional fermented soy food whose characteristics are so unusual that it is called by its native name in every European language. Natto as a delicacy first appeared in Japanese culture in the 11th century and is thought to have been used as an offering at altars. The viscous, silky threads of PGA on soybeans are formed via fermentation with Bacillus species. Still eaten primarily in Japan, it is cheap, nutritious, and easily made at home.
From Food to Cosmetic Ingredient
For a thousand years PGA was consumed as natto until the unique “mouth” and “skin feel” of PGA led to its exploration in the early 2000’s as an active ingredient in topical cosmetic formulations. Back then, PGA was manufactured in East Asia by Tung Hai and Vedan International and marketed as super moisturizers, with up to ten times the moisturizing capacity of highly sought after and—at roughly 400 USD per pound—highly expensive hyaluronic acid. Knowledge of PGA was prevalent in East Asia from natto and it was not until the mid-2010’s that PGA gained global awareness. More research came out and PGA was explored in numerous applications for its water-soluble, water-absorbent, and metal-binding properties. Unfortunately, commercial adoption has been hindered by PGA’s expensive fermentation and purification processes.
Process Improvements Enable New Products
Since the 90’s, high productivity Bacillus strains, optimized fermentation conditions and cheaper feedstocks have significantly lowered the cost of goods (COGS) of PGA. A lower COGS means innovators are no longer constricted to commercializing highest-margin products. Likewise, innovators may be able to tailor the properties of PGA, like molecular weight. High molecular weight (MW) “linear” PGA has long, unmodified repeating units of glutamic acid that can reach over a million Daltons. These long strands attract and retain water, unique properties that are exploited as texturizers and film-formers in food and cosmetics, respectively. As a dietary supplement, PGA’s binding affinity have been shown to increase calcium absorption in postmenopausal women. Next, lower MW linear PGA can be used as non-toxic chelating or flocculating agents, as in eco-friendly wastewater treatment.
As Biodegradable Replacements for Acrylates
High charge density and γ-amide linkages make γ-PGA an attractive target for replacing commonly-used acrylate polymers in many uses, especially in applications requiring biobased content and biodegradability. This includes replacing acrylate- and starch-based superabsorbent polymers (SAPs) with modified “crosslinked” derivatives of PGA. Linear PGA is crosslinked to form a three-dimensional lattice with sodium or potassium counter-ions that create an osmotic gradient that draws water in, creating a water-swellable biobased SAP. Many everyday absorbent hygiene products use a combination of SAP and cellulose fluff, including infant diapers, feminine napkins, and incontinence products.
What We Do at Ecovia Renewables
At Ecovia Renewables we create high-performing, eco-friendly ingredients and materials for personal care products based on non-toxic and natural PGA. Our bioprocess employs high-efficiency, non-GMO strains to create a suite of 100% biobased water-soluble and water-swellable Ecovia Biopolymers. Applications we are exploring include using Ecovia Biopolymers as soil additives for water retention to super-absorbents in infant diaper cores to ingredients for food and industrial uses, among many others.