Gleams & Notions

A Non-Paraben Preservative

By Harvey M. Fishman, Consultant | November 9, 2009

Among the companies that have developed non-paraben preservatives is Schülke, which has U.S. offices in Mt. Arlington, NJ. Several of the company’s mixtures are effective against bacteria, yeast and molds.

Euxyl K 700 (INCI: Phenoxy- ethanol (and) benzyl alcohol (and) potassium sorbate (and) tocopherol) is a liquid with a pH of 5.5 that can be used in a leave on or rinse off formulation. The company’s recommended concentration for either rinse off or leave on is 0.5-1.5%. Below is a list of minimum inhibitory concentrations (MIC) of Euxyl K 700 against various organisms. A repeated challenge test was used to determine the efficacy of the preservative. After growing the organisms in a soya agar or Sabouraud-dextrose media, the preservative is streaked on it at various time intervals.

Its effect is evaluated on the basis of microorganism growth on the nutrient gel. The longer it takes for growth, the more effective is the preservative. Schülke states that a well-preserved product should remain growth-free for six inoculation cycles in order to ensure a shelf life of 30 months.

Euxyl K 700 can be used in anionic, cationic or nonionic systems, butis not effective in a formula pH above 5.5. It does not foam and about 2 grams of K 700 will dissolve in 100 grams of water at 20°C.It is readily soluble in propylene glycol, propanol or acetone.

Another choice is Euxyl K 701 (INCI: Phenoxyethanol (and) benzoic acid (and) dehydroacetic acid (and) ethylhexylglycerin).This clear yellow liquid has a water solubility of 10 grams per liter at 20°C.Suggested use level for leave-on or rinse-off products is 0.4 to 1.2%.It should be added during the cooling phase at 40°C, and the pH should not be above 6.0.

More Choices

In Europe, dehydroacetic acid cannot be used in aerosols, therefore, K 701 is also prohibited.

Euxyl K 702 (INCI: Phenoxy- ethanol (and) benzoic acid (and) dehydroacetic acid (and) ethylhexylglycerin (and) polyaminopropyl biguanide) is another preservative that is effective when used between 0.2-1.0%.The challenge test described above showed that K 702 prevented growth even after three months storage at 40°C.The K 702 should also be added while cooling at 40°C, and it is stable up to pH 6.0.Yellow discolorations will occur in the presence of iron ions. It is 1% soluble in water at 20°C.

A formula showing its use follows:

W/O Moisturizing Cream

Phase A
Polyglyceryl-4 isostearate (and) 5.0
cetylPEG/PPG-10/1 dimethicone
(and) hexyl laurate
Mineral oil5.0
Caprylic/capric triglycerides5.0
Isopropyl myristate5.0
Phase B
Sodium chloride0.8
Hydroxyethyl cellulose0.8
Phase C
Euxyl K 7020.6
Perfume and colorq.s.

No heating necessary.Add silica to the oils in phase A with adequate agitation. Dissolve the cellulose in the vortex while mixing phase B.Add the salt after the cellulose is fully hydrated. Add phase B to phase A while mixing. Homogenize. Add phase C in order listed.
About the Author
Harvey Fishman has a consulting firm at 34 Chicasaw Drive, Oakland, NJ 07436,, specializing in cosmetic formulations and new product ideas, offering tested finished products. He has more than 30 years of experience and has been director of research at Bonat, Nestlé LeMur and Turner Hall. He welcomes descriptive literature from suppliers and bench chemists and others in the field.