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While essential oils do show some ability to preserve oils, rosemary oleoresin and Vitamin E are your best bets for protecting against oxidation and extending shelf life. Look for one or the other, and preferably both, in your oil-based products.
If you have an oil-based product you have not opened because you intend to use it later put it in the refrigerator. Keep products that you are currently using in a cool, dark place.
Look for products packaged in dark glass, with dispenser tops that limit exposure of the products to air.
Perhaps no other issue is more controversial than natural preservation of water-based products. Many preservative suppliers point out that the obstacles to so-called natural preservation are almost insurmountable. "A single natural preservative just isn't practical," insists Mary.Chervenak of Dow Biocides. "Although some organic oils and other natural products have antimicrobial activity, their biocidal capabilities are limited and they usually cannot withstand the continuous reinoculation that most personal care products must endure.
Most personal care formulations use preservatives in combination to combat the introduction and reintroduction of bacteria." While we all agree that rampant bacterial growth is undesirable, most of us are reluctant, and for good reason, to use products with parbens in them. Fortunately some alternative safe preservatives do exist, although the choices are still limited.
The bactericidal and mold inhibitor good guys
Cosmocil CQ is paraben-free bactericide that has so far been given a clean bill of health. Geogard, composed of gluconolactone and sodium benzoate, is accepted as a preservative for use in organic products. Leucidal, derived from a lactic acid bacteria, is new and potentially of great utility, however both Geogard and Leucidal may be skin irritating (see sodium benzoate below). Sodium Hydroxymethylglycinate, derived from glycine, is a broad-spectrum preservative effective against bacteria, yeast and mold.
Mold inhibitors such as sorbic acid and potassium sorbate are very safe, but they have no effect against bacteria. Sodium benzoate is also considered safe, but may irritate skin when applied topically over extended periods of time. Never confuse it with alkyl hydroxyl benzoate, which is the chemical name for parabens.
Phenoxyethanol is often described as a safe, paraben-free alternative. While it is an improvement over propylparaben the jury is still out, with the Green Beauty Guide citing some evidence before giving it a definite “no” vote. While phenoxyethanol does not release formaldehyde it is known to work best when used with with diazoldinyl urea, which does. I would be a tad suspicious of phenoxyethanol listed alone.
Grapefruit seed extract—GFSE has long been touted as a natural preservative. The truth is that it is neither natural nor a preservative. Extensive chemical processes break down the grapefruit seed into synthetic quaternary ammonium compounds, and a study from the Institute of Pharmacy Ernst Moritz Arndt University, Greifswald, shows that when GFSE is effective it is due to either the added synthetic preservative agents or the synthetics contained within. In its natural form it shows no anti-microbial activity. Citrus seed extracts are not approved for use in Europe and Japan.
Source : MVOrganics