Home Cosmetic Science Talk Formulating Do saturated free fatty acids turn rancid?

  • Do saturated free fatty acids turn rancid?

    Posted by FVDK on March 19, 2023 at 6:39 am


    Free fatty acids are unstable and prone to oxidation. But does that only happen with unsaturated & polyunsaturated acids or also with saturated acids? How stable are Palmitic acid, Myristic acid and Stearic acid as free fatty acids (not as triglycerides)? Can these 3 mentioned saturated fatty acids be used in a formulation as free fatty acids, or will they turn rancid in time? If they do get rancid or oxidate, could vitamin E or other ingredients prevent that from happening?

    Thanks in advance!

    ketchito replied 6 months ago 4 Members · 13 Replies
  • 13 Replies
  • ketchito

    March 19, 2023 at 6:49 am

    Saturated FFAA are more stable than unsaturated and polyunsaturated, because they don’t have double bonds, which are prone to attack by for instance, oxidants.

    Yes, a way to protect these double bonds is by using an antioxidant (tocopherols are ok, but synthetic ones work even better).

    • FVDK

      March 19, 2023 at 6:54 am

      Thank you so much for your quick reply! So could I use saturated FFA without any antioxidants at all? I’m planning to use a very high amount of FFA in a formula.

  • ketchito

    March 19, 2023 at 6:57 am

    Yes, but antioxidants don’t only protect your FFAA in a formula, but also, your fragrance, your dyes, etc. For me, antioxidants and chelants are always a must in a formulation.

    • FVDK

      March 19, 2023 at 6:58 am

      Thanks for your help 🙂 What is your background in chemistry if you don’t mind me asking?

  • ketchito

    March 19, 2023 at 7:00 am

    My background in chemistry is that I’m a chemist 🤓

    • FVDK

      March 20, 2023 at 4:35 am

      Thanks 🙂

  • SnowBunnyChemist

    March 19, 2023 at 9:11 am

    Hello, I’m not sure what you’re trying to formulate but I just wanted to mention if you are concerned about oxidative stability -

    I just wanted to mention a few whole (not fractionated) oils and butters to you.

    The following are rocksolid stable:

    Jojoba oil is incredibly stable - even under high heat conditions.

    Also, don’t forget good old coconut oil – it is literally rock solid when it comes to stability.

    Kokum butter is also incredibly stable, as is Cocoa butter.

    However, for addressing skin care problems - formulations with polyunsaturated oils are technically the most effective.

    Unfortunately they are also the most susceptible to oxidation and also the most expensive. But you can bump that time up with tocopherols.

    However, if you are attempting to address a serious skin repair problem you really need to consider utilizing them.

    I know you already said you only plan on using saturated FFAs but I just wanted to throw that in there. Good Luck 🍀

    • FVDK

      March 20, 2023 at 4:33 am

      Thanks for your input! I would like to formulate a product for hair, not skin. The reason I want to mostly incorporate free fatty acids as opposed to triglycerides is because I’m focusing on the CMC in the cuticle layers of the hair shaft which is composed of free fatty acids (and covalently bound fatty acids).

      Triglycerides won’t form membrane layers and reside mainly in the cortex & medulla. I’m also prioritizing the aforementioned saturated fatty acids because they are the most abundant ones in hair (Oleic acid is abundant as well, but since that’s unsaturated I’d rather not use that in free form due to oxidation).

      Cocoa butter contains a good amount of the fatty acids I’m interested in (Palmitic, Stearic, Oleic) but in triglyceride form. I’d have to hydrolyze Cocoa butter to turn the triglycerides into FFAs, but then that would also affect the unstable Oleic acid. Same for Kokum butter.

  • philgeis

    March 19, 2023 at 9:30 am

    Rr fatty acids you mentioned, I’d not worry that much about chemical oxidation. They can be metabolized by microorganisms via “beta oxidation” - that would require gross contamination.

  • ketchito

    March 20, 2023 at 6:45 am

    @SnowBunnyChemist Could I see the data on PUFA’s best effect on skin care products?

    @FVDK I’d be cutious on formulating hair care products with FFAA. They can be irritating to the scalp (the oleic acid you mentioned, is linked in the irritation part of seborreic dermatitis, formed as a by product of triglyceride’s metabolism from Malassezia yeast).

  • SnowBunnyChemist

    March 20, 2023 at 10:04 pm

    @ketchito Hi, PUFA’s are strongly anti inflammatory through multiple biochemical pathways. They are like liquid miracles for the skin, like urea and alantoin and glycerin. 🙂

    They also modify biochemical cellular messaging by multiple modalities.

    Beyond amazing.

    Topical administration of PUFA’s has been demonstrated to terminally enter the systemic circulation.

    There is a ton of research available. Here is an article addressing both dietary and topical administration.

    (I am a licensed skin care provider, also with a formal university medical sciences /chemistry education and I use oils for everyyyything in skin care.)


    • ketchito

      March 21, 2023 at 9:45 am

      Call me skeptic, but I like solid data 🤓. I checked the site from your link, and they mention only two papers about topic use of these oils. By the way, papers are from 1974-1975, and they were about a very specific defficiency. In the case of one of them, you can even read this:

      “Control patients who were not malabsorbers and were not deficient in essential fatty acids showed none of these changes after cutaneous application of sunflower-seed oil.”

      So, in people without the defficiency, there were no changes in TEWL, scaling, etc after topical application of the product.

      There are better molecules to address skin issues, and to me, vegetable oils at functional doses have more drawbacks than benefits.

  • SnowBunnyChemist

    March 20, 2023 at 10:20 pm

    Hi FVDK, kk got you. Sounds like a great hair project.

    Have you maybe considered caprylic and capric MCT’s - they are still saturated and are rock stable and will not easily oxidize.

    Also highly heat stable.

    Is this for a rinse-off or leave-on?

    I would still watch out for Oleic if leave-on…

    best ⛄️ (still cold here:)

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