Preservative combination - Chemists Corner

Tagged: cosmetic, formulation, ingredients, stability

Formulating

Preservative combination

Posted by SaraLee on July 27, 2021 at 5:45 pm

Hey all! First post:
Anyone see any glaring gaps of broad spectrum coverage in this preservative combination? As long as I keep the pH at or below 5 and use GMP? Any percentages I should bump up?

.2% Sodium Dehydroacetate + .2% Potassium Sorbate + .5% Glucono delta lactone + 1% Caprylyl Glycol/Glyceryl Laurate/Glyceryl Undecylenate (Jeecide Cap-7) + .2% edta

Also any foreseeable issues of compatibility with anionic, non-ionic, cationic or emulsion systems that I missed?

Last thought - is EDTA necessary as a chelator with the glucono delta lactone already included?

SaraLee replied 3 years, 3 months ago 4 Members · 9 Replies
9 Replies

suswang8

Member
July 27, 2021 at 6:00 pm

(Me suspects they will want to see your entire formula before opining on preservative and chelator adequacy . . . )
SaraLee

Member
July 27, 2021 at 6:41 pm

I’m planning on trying it in a few different formulations including a non-ionic surfactant based shampoo and a cationic conditioner, but for now I’ll just post my lotion formula which uses anionic surfactants as emulsifiers:

 61% distilled water

 5% cacao butter

 10% coconut oil

 10% olive oil

 8% ecomulse (Glyceryl Stearate (and) Cetearyl Alcohol (and) Sodium Stearoyl Lactylate)

 2% vegetable glycerine

 .2% sodium dehydroacetate

 .2% potassium sorbate

 .5% glucono delta lactone

 1% Jeecide Cap-7

 .3% siligel (Xanthan Gum, Lecithin, Sclerotium Gum, Pullulan)

 .2% edta

 .1% vitamin E

 1% vanilla extract

 .5% essential oil (depends on fragrance)

Heat water and oils/emulsifying wax separately to 140F. Blend together water and gums with immersion blender. Slowly pour in oils. Add remaining ingredients and blend thoroughly.
PhilGeis

Member
July 28, 2021 at 9:51 am

What’s pH?
I’d drop the DHA and sorbate in favor of Benzoate and Gluconolactone as you have EDTA (target 0.1%). The esters are vulnerable to pseudomonad esterases. as pseudomonads are primary risks for shampoos, this is a pretty weak system. What about some benzyl alcohol.
SaraLee

Member
July 28, 2021 at 1:27 pm

Thanks Phil! pH is 4.5. Would phenoxyethanol or benzyl alcohol be more preferable as a replacement for the glycol? Or phenethyl alcohol? I’d also like to limit the likelihood of dermal irritation or allergic reaction to any ingredients. I’m concerned about my non-ionic surfactant based shampoo (coco glucoside) inactivating a benzoate which is why I was leaning towards sorbate as a fungal/yeast preservative. Any reason you prefer benzoates? DHA would more serve as a booster right? Not to prevent contamination, but to reduce growth potential? Is it overkill to throw it in with a broad spectrum blend?
SaraLee

Member
July 28, 2021 at 1:59 pm

I also just found a blend of phenylpropanol (70%) and ethylhexylglycerin (30%) claiming to be broad spectrum. Would it fall under the ester category you mentioned though? Sorry for the 3rd degree - I’m just a high school graduate/house wife/former Marine trying to learn as much as possible and not fall into the chemophobic trap that is the internet
PhilGeis

Member
July 28, 2021 at 10:28 pm

Sorbate would not suffer a different fate than benzoate. Prefr benzoate due to stability and general use in many shampoos largely due to synergized efficacy with surfactants - and my experience. I like it with Kathon but i know that bothers some folks
DHA is merely another organic acid.
I’m not so familair with Phenylpropyl - it’s not in ester worry but also not broad spectrum.
Fungi are very rare contaminants of shampoos. Phenoxy works well with ethylhexylglycerine - good idea. Maybe those with benzoate and EDTA.

Whatever you do, let us know how it fares in challenge.

Good luck!! I’d say Semper Fi - but I was just RA.
SaraLee

Member
July 29, 2021 at 1:02 am

Ok thank you so much for the advice. Will do! And thanks for your service!
justaerin

Member
July 29, 2021 at 1:54 am

Hello, fellow hobbyist!

This is anecdotal, but I haven’t had good luck with that emulsifier staying stable when much under pH 6, so 5 may be an overly optimistic rock-bottom. Also make sure it is under 40 C before you add anything in the cool down. It doesn’t like being rushed. I wrecked a batch with optiphen at 45 C.

I don’t know how much of a lift or effect you’ll get from 1% vanilla extract, because I’m assuming that you mean the kind for cooking. In which case I would put it in the heated water phase. Remember to check the IFRA or supplier recommended safe usage for any essential oils.
SaraLee

Member
July 29, 2021 at 2:18 pm

Ok I will! Thanks so much! Very helpful info