I repeatedly get asked “what is the best preservative to use in my natural product?” so I thought I’d address it here. Basically, there is no ‘best’ preservative and preservatives will behave differently in different formulations. So, unfortunately, there is no way to predict whether or not your preservative will work. It really is a matter of trial and error.
Preserving a product means to inhibit growth of microorganisms. These microorganisms are broken up into two categories; bacteria and fungus (including yeasts). For identification purposes, bacteria are categorized as either gram positive or gram negative. This is dependent on their ability to take up a certain dye which is determined by characteristics of their cell wall. Some preservatives work better at inhibiting one or the other. The term broad spectrum means that the preservative is effective at inhibiting a wide range of microbes in both categories.
Some of the new preservatives, although considered more natural, need to be used at much higher concentrations than some of the ‘tried and true’ preservatives. This may increase the possibility of irritant reactions due to the higher amounts. So please try to use the lowest amount possible that will work in your product.
That said, I’ll go over some of the preservatives that I use for natural products.
Trade Name
Geogard Ultra (sold by Lotioncrafter as Neodefend)
Sodium Benzoate and Gluconolactone
Broad spectrum
Approved by ECOCERT. Activity is higher in an acid environment (pH 6).
Sodium Benzoate
Sodium Benzoate
0.1- 1%, lower amounts work fine w low pH
Primarily anti-fungal with less anti-bacterial
Its activity increases in a more acid environment. The most effective pH is around 4, at higher pH levels more sodium benzoate is required.
Biguanide 20
Polyaminopropyl Biguanide
Cationic broad spectrum but sometimes weak on fungus
I like it for clear products like distillates, toners. Do not use with xanthan gum or liquid soap.
Leucidal Liquid
Leuconostoc/Radish Root Ferment Filtrate
Broad Spectrum
Approved by ECOCERT. For me this has not worked well in many formulas. I’ve had some luck using it with rather clear toners though.
Potassium Sorbate
Potassium Sorbate
Primarily Anti-fungal
Most active at pH 4-5, use more above that.
Phenoxyethanol (and) Caprylyl Glycol
Use between pH 4-8. Broad Spectrum
Has worked well in most products for me
Optiphen ND
Phenoxyethanol (and) Benzoic Acid (and) Dehydroacetic Acid
Works best below pH 6, broad spectrum
Works well in most products
Optiphen Plus
Phenoxyethanol (and) Caprylyl Glycol (and) Sorbic Acid
Works best below pH 6, broad spectrum
Works well in most products
Most active against gram negative bacteria
More soluble in oil than water which is why it is often sold in a combination.
Plantaservaitve Wsr (Honeysuckle)
Lonicera Caprifolium Extract, Lonicera Japonica Extract
Broad Spectrum, Must be neutralized with citric acid first.
Has worked well in some situations.
Phytocide OS
Sambucus Nigra Fruit Extract
Broad spectrum
This is oil soluble and I’ve found it to work in limited products.
Linatural NLPO
Citrus Aurantium (orange oil), Cymbopogon Citratus (lemon grass oil), Sesamum Indicum (sesame oil)
Broad spectrum
Has worked in some products. Has a quite citrusy aroma.
There are other so called natural preservatives besides these including aspen bark, willow bark, and various fermentation filtrates as well as preservatives based on essential oils.
Some products are just harder to preserve than others, particularly those that contain a lot of herbs and nutrients. Bacteria and fungus love herbs and nutrients as much as we do.
I never recommend silver or Tinosan products. I fear that it builds up in the environment and will cause problems with time. Perhaps I’ll be proved wrong but I am just not comfortable using a heavy metal.
There are many other so called natural preservatives that you can learn about initially by browsing supplier’s websites. If you want to try several, you’ll just have to buy a few, use them in your product and see what happens.
Before paying for expensive challenge testing, try challenging them yourself initially. To do this, make your product, split into several jars and use a different preservative in each jar (measuring each carefully). Stick your dirty fingers into the jar daily over several days and let it set for several weeks to see if visible fungus develops. But remember, just because visible fungus doesn’t grow does not mean your product is not contaminated. The word microbe is short for microorganism. These are things that cannot be seen with the naked eye, sometimes they are even too small to see with a standard microscope. But that does not mean they are not dangerous.
Remember that preservatives are necessary to make a safe product. You don’t want your customers rubbing bacteria and fungus on themselves.
Learn more about Sagescript microbiology testing here.http://www.sagescript.com/microbiology