Need some help extending the shelf life of a Natural Toothpaste

I am currently redesigning a toothpaste to extend shelf life and prevent separation. The toothpaste contains calcium carbonate, sodium bicarbonate, xylitol, minerals, flavoring oils, water and a colloidal silver suspension. The colloidal silver may be acting as a preservative/antimicrobial as testing of the product returned below 1000cfu/mL for bacteria and below 100 cfu/mL for yeast and mold.

As such I have three issues I need to address, 

(1) stopping the separation of the product which occurs after a period of months. I have looked into binding/thickening agents and have arrived at the following: guar gum, xantham gum, gum arabica. Would these be suitable choices as a means to stop separation?

(2) Determining whether or not my toothpaste is sufficiently preserved?
 (I understand that a preservative challenge test is likely the best option but want to avoid spending the money if possible.)

(3) Determining a way to better preserve my toothpaste in a 'natural' manner if possible or at least a less contentious semi-natural way if required. I am looking into self-preservation quite extensively as an option whether that be reducing water activity, changing pH etc but I am not quite sure how to go about this especially considering the function and nature of toothpaste?

If anyone could offer advice on the above three questions that would be fantastic.

Thanks

Comments

  • Some suggestions listed below:

    1 Colloidal Silver (or pretty much any Silver compound) is unsafe for toothpaste or any other use where it can be ingested
    https://nccih.nih.gov/health/silver
    https://en.wikipedia.org/wiki/Argyria

    2 I don't see any emulsifier or at least surfactant that's holding oils soluble.
    IMO that's the most likely cause of separation.

    3 Depending on your definition of natural, you may add some small amounts of Potassium cocoate (coconut oil saponified with Potassium hydroxide) to give it some foaming, extra cleaning. It requires a bit high pH to remain stable.
    While a bit high (alkaline) pH ain't that troublesome in toothpaste (some contain Sodium bicarbonate to rise pH), don't overdo it either as to avoid excessively high pH.

    4 Calcium bicarbonate is much more water soluble than Calcium carbonate.
    Thus less likely to precipitate out of solution.

    5 Check to see if Erythritol has better anticaries action than xylitol.

    6 You can choose essential oils that have the highest anticaries action according to studies (i.e. cinnamon oil if I'm not mistaken).

    7 For a more "natural" approach you could use a little ethyl alcohol. 
    Many commercial mouthwashes already have lots of it.

    8 Other than that, you'd need synthetic preservants.

    9 You can try an anhydrous (no water) formulation with coconut oil+gum to see if it works.
    I believe studies show some anticaries activity from coco oil.
    Anhydrous formulations can sometimes be formulated preservative free.

    10 Please keep us updated with your results.
  • Thanks for the input Gunther I will start looking into these.

    I also missed castile soap in the ingredients list I provided. So that is filling the role of emulsifying agent and surfactant. That said I do like the idea of sodium cocoate or potassium cocoate. 

    I also just made a small batch with the addition of some bentonite clay. the reasoning behind this was the hydrophilicity of the clay and its fine particle size might help with the binding and consistency of the product, it would also function as an additional mild abrasive. The bentonite clay did thicken the product up, however, did require the addition of more water which might pose a preservative issue. 

    I might look into a coco oil or similar anhydrous formulation. I know glycerine could aid in making a anhydrous formulation, however, I am not sure whether I should avoid using it due how contentious it is for some people.


  • BelassiBelassi Member, PCF student
    edited June 2018
    I also missed castile soap in the ingredients list I provided  :p  No thanks. And there's nothing at all wrong with glycerin.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • I agree that there is nothing wrong with glycerin. That said what people perceive as 'natural', 'safe' or 'healthy' can affect the marketability of a product. As such I am going to experiment with not using glycerin. 

    I am going to use potassium cocoate as the surfactant / emulsifier and I am thinking that I will try to reduce the water content sufficiently to prevent microbial growth through the replacement of water with coconut oil, a binding agent and potentially glycerin.


  • BelassiBelassi Member, PCF student
    Have you actually tasted potassium cocoate? It will literally be like washing your mouth out with soap.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • DASDAS Member
    1000 cfu is very bad, for something you put in your mouth anything over 100 is unacceptable (I think that's the limit for oral care, and it's still too much). 

     (I understand that a preservative challenge test is likely the best option but want to avoid spending the money if possible.)

    Don't. You will spend more money if you get sued for selling a rotten product. At least put some benzyl alcohol on it. Is ecocert/COSMOS compliant.
  • Thanks DAS you are completely right I got mixed up with the CFU value it is 100 which I would want to be far below. As for the preservative challenge test I will do one but after performing some of my own microbial tests on the prototype with dipsildes.

    I think the formulation will end up being something like this 

    Calcium Carbonate (abrasive)
    Sodium Bicarbonate (neutralizing agent + abrasive)
    Xylitol (sweetener + humectant)
    Sorbitol (moisturizer)
    Minerals 
    Water 
    Flavoring Oils
    potassium cocoate (surfactant/emulsifier) or another non SLS surfactant
    Xanthan Gum (binding agent/Thickener)
    Benzyl alcohol (preservative)

    I will have to investigate the preservation of the formula however I would hope that by decreasing the water content and metabolizable ingredients it may not require more preservation than the benzyl alcohol.

  • Try sodium Benzoate  (Ecocert) and Potassium Sorbate (Ecocert), they go together and usually do OK!
    Dr. Catherine Pratt
    (B.Sc with HONS I , Ph.D Analytical/Organic Chem and Microbiology), Cosmetic Chemistry IPCS)
  • After reading more into preservative properties of Benzyl alcohol ( https://www.americanpharmaceuticalreview.com/Featured-Articles/38885-Antimicrobial-Preservatives-Part-Two-Choosing-a-Preservative/ )

    I am wondering how it would function in a toothpaste. The pH required for Benzyl alcohol to be most effective is below 5, however, a toothpastes function requires it to be neutral or slightly basic to prevent dental carie formation. would the benzyl alcohol still function at a pH of around 8 or would this cause issues with deprotonation of the alcohol group and a subsequent loss of function? 

    Also does anyone happen to know what category toothpaste is classified as under USP51? I am assuming category 3? 

  • After further researching preservatives systems that would function under the formula conditions of toothpaste, i.e. neutral to slightly basic. I am going to try the following:

    EPE 9010 0.5% (phenoxyethanol 90%, ethylhexylglycerine 10%)

    1,3 propanediol 4% 

    I plan to dissolve them in a separate liquid phase under high shear that I would then add as a third phase to the combined ingredients. 


  • Hey there,
    You can get a product called Euxyl 9010 from one of the small businesses like lotioncrafter or making cosmetics and they will have it all made up in the correct ratios. Please so try it, I know that it works.
    Kind Regards
    Dr. Catherine Pratt
    (B.Sc with HONS I , Ph.D Analytical/Organic Chem and Microbiology), Cosmetic Chemistry IPCS)
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