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Natural preservatives at pH>6
Hello!
I have been reading discussions on preservatives for days, but I am still failing to figure out a solution. I have a client who is insisting on a product with sodium ascorbyl phosphate, expecting 18+ months shelf life (I am in the process of explaining how ambitious that is), and, of course, wants it to be naturally preserved (preferably with Preservative Eco/Microkill). I feel stuck as I am afraid to go below pH 6 with SAP and above pH 5.5 with natural/ecocert/cosmos compliant preservatives. My only hope for now is Spectrastat G2 (Caprylhydroxamic acid, glyceryl caprylate, glycerin) which I’ve never worked with and I am not sure how efficient it would be as a stand alone preservative. I am a germofob and always vote parabens and am seriously starting to hate green formulating. I have to mention that the product will be loaded with hydrosols (preserved with polylysine) and aloe. I would really appreciate any thoughts anyone might have.
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24 Replies
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I recently tried it in a formula and found it to be weak on yeast/mold, so I would not recommend it as a stand alone preservative. Couple it up with a fungicide + chelating agent and you should be in good shape.
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Personally, I wouldn’t let a client dictate to me what preservative system will be used. This is a terrible trend in formulation if you ask me.
But to your situation, I would agree to use the ingredients they want but get an agreement with them that you do not have to guarantee the product will be safe or stable. Make it clear to them that any microbial contamination will not be your responsibility. If the client wants to dictate how the product is formulated, that should take the responsibility of failure off of you.
As an aside, I wish instead of “green formulating” people practiced “safe formulating”
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I second what’s been said here. My client insisted on a ‘natural’ preservative and it has been a veritable nightmare. The problems are two-fold:
1. Natural preservatives are generally not very good.
2. A natural product is likely to have lots of other natural ingredients which necessitate a better-than-average preservative.
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I think a trend we’re seeing here is a misunderstanding of what exactly comprises Preservation.
It is not a matter of simply adding a Preservative ingredient to a formula. It’s hurdle technology that includes chelating agents, glycols/diols to reduce water activity and bacteriocides and fungicides that are compatible with the formula.
I use natural preservatives all the time and I rarely fail a PCT because I always use hurdle technology approaches to preservation.
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MarkBroussard said:It is not a matter of simply adding a Preservative ingredient to a formula. It’s hurdle technology that includes chelating agents, glycols/diols to reduce water activity and bacteriocides and fungicides that are compatible with the formula.
I second it!
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Thank you all for the comments!
MarkBroussard said:I recently tried it in a formula and found it to be weak on yeast/mold, so I would not recommend it as a stand alone preservative. Couple it up with a fungicide + chelating agent and you should be in good shape.You find Spectrastat or Eco weak on mould? I am using a chelator already. Any suggestions on a fungicide?
Perry said:As an aside, I wish instead of “green formulating” people practiced “safe formulating”I couldn’t agree more. There is a trend I am seeing on the local market where there is a bunch of vitamin C serums containing MAP or SAP preserved with pottasium sorbate and sodium benzoate. It was frustrating at the beginning, but now it’s just scary. I find it very hard to understand this trending preservative-free frenzy.
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Yes, Phenethyl Alcohol would work well in this type of formula
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MarkBroussard said:Yes, Phenethyl Alcohol would work well in this type of formula
Will look into it. Thank you!
Speaking of vit C, what are you thoughts on Tetrahexyldecyl ascorbate?
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It is my preferred form of Vitamin C to use in formulations.
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MarkBroussard said:It is my preferred form of Vitamin C to use in formulations.
I agree. And it’s so easy to work with!
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@MarkBroussard, I had high expectations from it but it oxidises and causes loss of viscosity of polymers (I tried it with Aristoflex AVC, Sepinov EMT10 and Pemulen EZ 4U). The product changes color to yellowish in just a month.. I would appreciate if you can share your experience (maybe there is any specific formulation approach). I added BHT, tried tocopherol too. Nothing seems to work..
here is an example of how I use it:
Phase INCI % A Aqua 59.50% A Niacinamide 2.00% A Ceramides Evonik 5.00% A Tetrasodium EDTA 0.10% A Glycerine 3.00% A betaine 3.00% A Siligel 0.30% A Propanediol 2.00% B Coco-caprylate 1.00% B Octyldodecanol 2.00% B Ethylhexyl stearate 2.00% B Dimethicone fluid 2.50% B Cetyl Alcohol 3.00% B Cetearyl 1.00% B Mirystyl Mirystate 2.00% B Tocopheryl Acetate 0.50% B BHT 0.10% B Glyceryl Stearate/PEG-100 Stearate 4.50% C Bisabolol 0.50% C Tetrahexyldecyl
ascorbate5.00% C Germaben II 1.00% -
@ngarayeva001
What type of package do you use?
I use airless pumps an haven’t had discoloration at all. -
At a glance, the formula looks just fine. Have you done a knock-out experiment making a batch that does not include Tetrahexyldecyl Ascorbate to confirm that this is the ingredient causing the discoloration?
You might also try a combination of Tocopherol, BHT and Sodium Ascorbate to see if you get better stability.
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@Doreen, pump bottle. It’s however transparent PET plastic.
Thank you for an idea Mark. I will try a combination of antioxidants. -
I highly recommend that you also do a knock-out batch on the THD Ascorbate … that is not necessarily, nor definitively, your problem and best if you confirm it.
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Yes, I need to get rid of that siligel first of all. Then probably ceramides and niacinamide.. maybe bisabolol. Everything else looks less suspicious. Thank you again.
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At least in theory, tetrahexyldecyl
ascorbate is nearly as stable as any ester oil. I’d also start looking elsewhere too.BTW do you still have some spoiled product left? Heat it and let the phases separate; it can but not necessarily has to tell you more (unfortunately, decomposed THC ascorbate would likely colour water and not oil phase). -
We use that Spectrastat at 0.7% and have never had an issue, even with pea proteins and high aloe vera content. Also should include EDTA at 0.2%.
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Belassi said:We use that Spectrastat at 0.7% and have never had an issue, even with pea proteins and high aloe vera content. Also should include EDTA at 0.2%.
Thank you!
@MarkBroussard @Pharma @ngarayeva001 have you ever used/seen tetrahexyldecyl ascorbate being used at concentrations above 10%?
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What’s wrong with Siligel?
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Well apparently lecithin (that is part of siligel) is very hard to preserve. I like siligel, but I don’t need that trouble. I already rewrote all my formulas that contained siligel.
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@ngarayeva001What are you using instead of Siligel?
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@Meemcha we have used it at 18-20% in anhydrous product. Can’t speak much to performance as we didn’t perform any testing, the client just wanted a stable Vitamin C form with hiiigh percentage. it has not discolored in 50C oven and it has been almost 5 months
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