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Preservation Need for High Glycol Product?
I’m working on a hot-pour gelled product that contains 70% glycols (50% propylene glycol, 17% Dipropylene glycol). Packaging is a twist-up stick type like many common deodorants. The pH is ~4.5 (measured as a 50% mix with deionized water). I tested water activity and got a reading of 0.94, which seems a bit higher than I expected considering the glycol content but I haven’t had a chance to test a_w before now. I read that this should inhibit growth of many bacteria but I assume I still need something for yeast and mold and any hardy bacteria. I’m debating inclusion of some sodium benzoate, pentylene glycol, and/or methylheptylglycerin. The challenge is the product is being positioned as “microbiome friendly” - I need to ensure sufficient preservation but I’ve been encouraged to avoid ‘strong antimicrobials’ which could disrupt the beneficial bacteria balance. Any suggestions on preservative inclusions?
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9 Replies
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0.94 - about at the edge of Gram negative inhibition, not enough for other bacteria and fungi.
not picking on you - but how “microbiome friendly”?
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The info I got is a specific ingredient was plated with certain topical resident microbes in vitro and showed some vague positive results (promotion of some ‘beneficial’ bacteria, reduction of some others associated with malodor). Now I’m being asked to develop a formulation for further testing to show if the claim can be substantiated for a full product.
Do my selected preservatives (benzoate, methylheptylglycerin, pentlyene glycol) seem adequate to cover whatever may still grow?
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OK - maybe the Shisedo test. It’s BS but it’s out there.
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Would this material happen to be ScentARC?
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It’s not, though I technically can’t see what the components of the scentARC are
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what’s pH?
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it’s ~4.5, I dilute it 50% with DI water to get a reading since the product is a solid gel otherwise
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4.5 is the dilurted product - not the product itself.
How much water is in the product itself?
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~27% water
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