Alternative preservative and potentiator system for the personal care market

Traditional preservative chemistries are under regulatory pressure and/or public concern over their safety and environmental impact. As formulators seek alternatives to these traditional chemistries, they must also incorporate a safe and efficacious preservative system that can be used throughout the global market.

Abstract

Traditional preservative chemistries are under regulatory pressure and/or public concern over their safety and environmental impact. As formulators seek alternatives to these traditional chemistries, they must also incorporate a safe and efficacious preservative system that can be used throughout the global market.

Preservative development in recent years has focused on natural preservatives, or blends that offer new methods of preservation as well as other benefits to formulators. New introductions have included naturally-derived raw materials, multi-functional blends that offer moisturization benefits while keeping a product free of micro-organisms, and other systems that use the ‘hurdle technology’ approach to preservation.

Innovative blends of raw materials that provide beneficial attributes such as moisturization and potentiation, as well as antimicrobial efficacy, offer formulators new tools for preserving their products.

Introduction

A growing trend in the personal care market is the demand for products that contain natural materials. Personal care formulators are seeking raw materials that can provide the benefits of traditional chemistries and allow the products to be labeled as containing naturally-derived ingredients. At the same time, formulators must ensure that the products are well-preserved and safe for use over their shelf life.

Multifunctional preservative blends offer formulators the opportunity to reduce the number of ingredients, while providing other desirable attributes, such as moisturization. When the multifunctional blend contains naturally-derived components, it also allows the formulator to avoid using controversial preservative chemistries.

Lonza has created several, patent-pending novel blends containing polyhydroxy acids, anti-oxidants and/or food-grade preservatives that can provide a safe, natural and innovative route to preservation. These blends, such as Geogard® Ultra, are synergistic combinations of naturally-derived materials and ingredients from the food processing industry with a long history of safe use. They are globally accepted in most applications and provide an alternative to traditional preservative systems. These combinations provide antimicrobial efficacy against a broad spectrum of organisms such as gram-negative and gram-positive bacteria and fungi, unlike most natural products that are only effective against bacteria. An added benefit to the formulator when using these blends is the moisturizing property of the polyhydroxy acid component.

Geogard® Ultra

The newest addition to Lonza’s Geogard® portfolio of global preservatives is Geogard® Ultra (INCI name gluconolactone and sodium benzoate). It is a synergistic blend of glucono-delta-lactone (GDL) and sodium benzoate. Glucono-delta-lactone is a naturally-derived product of corn fermentation. It is also a natural constituent of many foods, including honey, fruit juices, wine and other fermented products, and is a ‘Generally Recognized as Safe’ (GRAS) food additive. It is a salt of gluconic acid and in an aqueous solution there is an equilibrium between gluconic acid and the lactone. As a natural food acid, it helps prevent microbial growth primarily through pH depression. The multiple hydroxyl groups on the GDL molecule attract water, resulting in a moisturizing effect when it is added to a skin care formulation. When combined with a traditional preservative, like sodium benzoate, it ‘potentiates’ the preservative and enhances the microbial tolerance of the finished product.

Sodium benzoate, or the sodium salt of benzoic acid, is another GRAS material that has been used for decades as an effective preservative in the food and personal care industry. Sodium benzoate, which occurs in nature, is a preservative which has a long history of safe use.

When Geogard® Ultra is added to a formula, the GDL and sodium benzoate work synergistically to provide preservation, while the GDL component adds a moisturizing benefit. The moisturization data and the synergistic efficacy data is presented in Figure 3 and Figures 4 and 5, respectively.

Moisturizing properties

The polyhydroxyl acid glucono-delta-lactone (GDL) has been recognized and used as a skin moisturizing agent for many years. The hydroxyl groups attract and hold water and can enhance the water retaining properties of topical preparations.

In a moisturizing cream, 2% glycerin was replaced by 1% Geogard® Ultra. The cream was then tested on nine subjects over the course of five days. The cream containing Geogard® Ultra resulted in larger increases in skin moisture level, as measured by transepidermal water loss (TEWL), during the test period, compared to the level of moisture demonstrated in the cream containing glycerin.

Antimicrobial efficacy

Blend efficacy

Preservative challenge studies with Geogard® Ultra have been conducted in shampoo, lotion and moisturizer formulations. The data from these studies is provided in Tables 2 and 3, which demonstrate that Geogard® Ultra has broad spectrum efficacy in the formulation, achieving counts of less than 10 cfu/gram at Day 7.

All of the preservative data was generated in studies that were conducted according to the CTFA Guidelines provided in Method M-3. The bacterial testing was done with a mixed pool of equal amounts of Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. Equal quantities of Candida albicans and Aspergillus niger were used for the mixed fungal pool.

Synergy data

Additional preservative efficacy studies were conducted on the components of Geogard® Ultra in order to demonstrate that the efficacy is indeed a synergistic, rather than an additive effect. The synergy that is observed with Geogard® Ultra is clearly seen in the fungal study shown in Figure 5.

Comparison data

In recent years, several alternative preservative systems have been introduced into the personal care marketplace. Preservative challenge studies with some of these new, non-traditional blends were conducted as described in the CTFA M-3 Method. Each product was tested at the highest recommended use rate provided in the product literature. These products were tested in a shampoo formulation with a starting pH around neutral. The results clearly demonstrate the superior efficacy of Geogard® Ultra versus the other alternative products under these testing conditions.

Application

Geogard® Ultra can readily be dissolved in the water phase during processing. Solubility is about 4 g/100 ml water at ambient temperature. It can also easily be dispersed in materials such as propylene glycol or glycerin and then incorporated into the formulation.

Formulation preservation is typically achieved at levels between 0.75 and 2%. The product can also be used as a potentiator with traditional preservatives, allowing the formulator to reduce the level of traditional approaches in their formulations.

A summary of the features and benefits of Geogard® Ultra is shown in Table 6.

Conclusion

The Geogard® products are globally acceptable for most personal care applications, which allows formulators to incorporate one ingredient for multiple markets, resulting in less raw material inventory. The multi-functional Geogard® Ultra product offers a safe way to maintain formulation integrity, while avoiding the use of out-of-favor preservative systems. Since the ingredients in this blend have a long history of safe use in the food industry, they can be used with confidence and assurance in many personal care formulations.

Geogard® products are never tested on animals and are environmentally friendly.