Home Cosmetic Science Talk Formulating Preservative combination

  • 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 2 years, 7 months ago 4 Members · 9 Replies
  • 9 Replies
  • suswang8

    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

    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

    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

    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

    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  :D

  • PhilGeis

    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

    July 29, 2021 at 1:02 am

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

  • justaerin

    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

    July 29, 2021 at 2:18 pm

    Ok I will! Thanks so much!  Very helpful info :)

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