Thursday, November 4, 2010

Preservatives: Inactivation by cellulose derivatives

There's one more thing to consider when using our preservatives - inactivation by cellulose derivatives! In this study, various cellulose derivatives were tested with various preservatives to see which ones retained their efficacy. Here's the list...

Methylcellulose reduced paraben efficacy.

Methylcellulose, sodium carboxymethylcellulose, and hydroxypropylmethylcellulose all reduced phenoxyethanol efficacy.

Gelatin reduced paraben efficacy.

Polyvinylpyrrolidone (PVP) reduced paraben efficacy.

A few naturally occurring thickeners work by protecting the bacterial cells in our creations so the paraben preservatives can't attack the beasties. These include acacia gum, tragacanth, sodium alginate, guar gum, and carageenan.

So what does this all mean? If you're using any of these ingredients, consider your preservatives wisely.


Alli said...

Do you have any updated info? I don't have a recipe. I was going to play around with difference percentages of hydroxyethylcellulose in water and build from there. Are there any new techniques for preserving gels with this ingredient?

Sara said...

Does this mean Xanthan Gum will also deactivate preservatives such as Optiphen. for instance, if I use Xanthan gum to thicken a face wash, is optiphen out of the question? I know optiphen doesn't play well with high surfactants and mostly water based anyway. SO I was considering 2-3% leucidal and also Microguard at .5% (GDL & SOdium Benzoate). This will also help with chelating(I think) and to bring down the pH since this particular wash will be with a castile soap as the surfactant only. Thanks!