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Formulating with Naturals—Skin Care
By: Arthur Georgalas
Posted: February 3, 2011, from the February 2011 issue of Cosmetics & Toiletries.
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Verbiage in the European Union’s (EU) REACH regulation states, “A naturally occurring substance is such [that is] unprocessed, or processed by manual, mechanical gravitational means; by dissolution in water; by flotation; by extraction with water; by steam distillation; or by heating solely to remove water, or which is extracted from air by any means.”5
The International Organization for Standardization (ISO) has issued vocabulary for natural aromatic substances in ISO 9235:1997, developed by the essential oil technical committee (TC) 54, and is currently working on ISO/NP 16128, “Cosmetics—Technical definitions and criteria for ‘natural’ and ‘organic’ ingredients and products,” which is at the approved new project stage for ISO TC 217: Cosmetics. Perhaps this is what Julie Tyrrell of NaTrue is referring to on the group’s website when she says, “The criteria for ‘natural’ claims should be finalized in the second half of 2011 and become operational from 2012 based on legislation in EU Parliament Article 20 that restricts false claims for cosmetics.”6
At the Bench: Lipids and Proteins
When formulators finally get to the bench to begin building natural skin care products, they can begin with the basic ingredients for emulsions: emollients, emulsifiers, humectants, thickeners, preservatives and other stabilizers, colors and fragrance. By focusing on these key components, one can identify candidates from their compendium of natural ingredients. Skin care emollients are generally easy since there are many to choose from, although they consist primarily of the natural triglycerides—i.e., fatty oils and butters. Add to this jojoba oil, strictly speaking a liquid wax ester, and squalene, a triterpene precursor of the sterol backbone distilled from olive oil as the major unsaponifiable liquid lipid and the basic ingredient list is all but exhausted.
Oxidatively unstable squalene becomes the elegant branched chain natural hydrocarbon squalane upon hydrogenation, a chemical process that is allowed in many certification schemes. Of course the question then arises: Is this truly natural? Other, lighter hydrocarbon components can be extracted by fractional distillation from natural oils, allowing for the adjustment of feel with mixtures of these oils, butters and other lipids. In general, lower molecular weight and less polar oils with branching and unsaturation give a lighter feel. Unsaturated oils may be challenged by oxidation leading to potential rancidity.
Considering the emulsification mechanism itself, the formulator might ask: What does nature do? How are stable oil and water systems established in nature? Nature works at a molecular level to produce the results observed macroscopically. Tiny, subcellular nanofactories churn chemicals out one molecule at a time that are then harvested by industry in bushel baskets and stainless steel vats. For instance, the olive oil that consumers serve at the dinner table begins as single triglycerides produced by the olive tree’s lipid synthesis pathway.