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  • Antimicrobial activity of organic acids & non-traditional preservatives

    Posted by Anonymous on June 24, 2016 at 6:38 pm

    Does anyone have a good resource for specific antimicrobial activities
    of individual preservatives, mainly organic acids and non-traditional
    preservative? I’m trying to make my own broad spectrum (or close to broad
    spectrum) preservative combination, but I’m having a tough time finding what
    preservatives are affective against what microbes (gram pos, neg, yeast, mold,
    etc.). I know I will eventually have to challenge test, but it would be nice to
    start with a theoretical broad spectrum combo first.

    I’m currently looking at dehydroacetic acid, dechlorobenzyl
    alcohol, caprylyl glycol, glyceryl caprylate, chlorphenesin, hexamidine
    diisethionate, phenethyl alcohol, etc.


    Parameters: mainly lotions, ph 4-5, sensitive skin,
    hypoallergenic, non-Parabens, non-Formaldehyde Donors, non-Isothiazolinones, will
    add EDTA, glycerin, antioxidant if need be

    PhilGeis replied 6 months, 1 week ago 6 Members · 15 Replies
  • 15 Replies
  • Anonymous

    June 29, 2016 at 3:15 pm

    I haven’t found any conclusive sources yet, but I thought I’d post some helpful links I’ve found for anyone who is interested in learning the specific antimicrobial activity of preservatives:

    Nice search tool (only the companies preservative products are included): 

    Interesting experiment with natural preservatives (note: this is not properly conducted study but helpful to get started): 

    Excellent Powerpoint Overview:

    Another popular overview (this is all over the internet but important place to start) thanks Makingskincare:

    List of many preservatives:

    I’ve been able to discern quite a bit of info on antimicrobial activity of individual preservatives from the above material. I’m still looking, if anyone as any other source.

  • OldPerry

    June 30, 2016 at 3:08 pm

    Great list of links.

    I’m not sure I understand what your question is however.

    You’ll find that in the cosmetic industry there are not a lot of compiled resources of data like the one you seem to be implying. This is because topics like preservatives are researched mainly by companies who are looking to use the information to create products (preservatives) to sell. They don’t readily share information that would be helpful to competitors.

  • Anonymous

    June 30, 2016 at 3:27 pm

    Thanks Perry. I figured as much since I’ve been researching the topic for weeks now. I ask the question because I would like to have complete control over what preservative ingredients go into my formula rather than using a commercial, premixed preservative combination. I guess I’ll just have to put the pieces together from various sources and challenge test different combinations.

  • Microformulation

    June 30, 2016 at 3:41 pm

    Start here. This is a pdf overview of Preservation. It is a few years old so the usage data (most popular preservatives) is dated, but the updated data has been posted on here recently.

    My advice on learning preservatives is to step away from a comapanies listing of preservatives and instead learn the chemical classifications (ex. paraben, organic acid, etc.) and the way to best use them. Then you will see once you select the correct preservative class or group that will work best in your Formulation, you can likely find a matching product from most suppliers.

    Also and lastly, preservation is based upon the characteristics of each Formula, not a one size fits all situation. In addition it is not just a matter of adding a preservative, mixing and being done. Follow the Hurdle Technique as outlined in the presentation. Factors such as the packaging, pH and Manufacturing sanitation have a factor as well. As David Steinberg says often, “The best preservative is good cGMP.”

    • Graillotion

      December 6, 2023 at 3:40 am

      Ever since the forum got the remodel….none of the old links work anymore. @Microformulation any chance you still have this link handy?

      I would enjoy the read.


      • This reply was modified 6 months, 2 weeks ago by  Graillotion.
      • Microformulation

        December 6, 2023 at 9:26 am

        It may be too old and the links may be expired. Much of it is covered in his text on preservation. You should get a copy.

        • Graillotion

          December 6, 2023 at 3:14 pm

          ???? As a reader of old forums…NONE of the old links work (pre-remodel)…nothing to do with expiration, everything to do with the remodel. ????

          I assume……you are referring to David Steinberg’s book?

          • Microformulation

            December 8, 2023 at 9:35 am

            Yes I am referring to David’s Book on Preservation from Allured Publishing. For an even deeper dive (but one which will require University training to follow effectively) is @PhilGeis ‘s book.

            • PhilGeis

              December 8, 2023 at 9:41 am

              Dave’s book is excellent - and you’re right - the best preservative is good GMP’s. As Rich Hennessy - an old pal and one of the great ancient cosmetics microbiologists - often said - there is no preservative system that the plant can’t screw up.

              My fav. example - ZPT 26% saturated solution RM we used for Head & Shoulders needed a preservative.

  • Anonymous

    June 30, 2016 at 4:59 pm

    @Microformulation This is a great presentation and pretty much what I was looking for. I actually was only looking for antimicrobial activity of preservative classes so that I had a starting point. So, this is a perfect source. Yes, I will be taking into account pH, packaging material, available water, pump bottle, good cGMP, co-preservative and chelators, etc. Hurdle Technique is a nice summary/outline to follow. Thanks, this will be very helpful.

  • Bobzchemist

    June 30, 2016 at 6:57 pm

    To add to Perry’s point, a lot of this information is also distributed in professional seminars or masters-level courses. The people who give the seminars certainly don’t want the information freely out on the web that they present for $1,000 to $2,000 per person - and the people who take the seminars/courses have no incentive to post it either.

  • Microformulation

    June 30, 2016 at 7:33 pm

    Remember that Free water (Aw) makes for a cool theory. However, it can not be calculated. It must be measured, both in R&D and also in Production. The equipment is specialized. Using Aw is one of the tricks of the “preservative free” market. But again, lacking the equipment to properly measure this value, it simply becomes a part of the overall Hurdle process, not a standalone.

  • Anonymous

    June 30, 2016 at 8:07 pm

    Is it even reasonable to get Aw down to 0.7 (or even 0.92) in a emulsion like a lotion and still have an aesthetically pleasing product? So, I guess my question is it worth measuring the Aw to try to get a “preservative free” claim? It seems like it would make more sense to to add glycols and polyols to the point where it’s aesthetically acceptable as part of the Hurdle process?

    • PhilGeis

      December 6, 2023 at 5:56 am

      Appreciate your attention to a complicated safety issue.

      The primary objective of preservation is to protect the consumer in use - versus microbes introduced during use. Hurdle depends on a series of weak components. Compromise of any one by consumer use, through stability, through any factor compromises preservation. These are common events and hard to control.

      Aw is not a relevant metric for some emulsions and getting to 0.7 often leaves product cosmetically diminished.

      There is no broad spectrum preservative and do NOT rely in supplier sales literature.. Construct a combination including multiple preservatives - one(s) esp. effective vs bacteria and one(s) esp. effective vs fungi and a chelator - EDTA.

      AND use a package that discourages consumer screwing up the product - esp. important for the poor systems that your list/claim describes. If you must chase the clean beauty/natural mythology - please use phenoxyethyl over phenethyl, try some glycols, esp. over the esters.

  • Anonymous

    June 30, 2016 at 9:24 pm

    Interesting article on that subject 

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