Adding Glycerin to products, need preserved?

[bodhi]

Hi Lindy, Your statement was that all products with glycerine need a preservative. I asked if you had any studies or reputable sources stating that, so that we could learn about this also.

Thank you for the link to the blog. One link references another blog and the other references a regulation on multi dose oral and injectable vaccines and allergy injections. I quoted the regulation below.

Im not sure where you got your information on glycerites or glycerine, but it is not correct.

Glycerites do not need and do not contain additional preservatives and can be stable for decades whether opened and used or not.

Liquid pharmaceutical drugs are preserved with glycerine in concentrations as low as 18% because glycerine is a preservative. This includes cough medicine which is often chugged right from the bottle by people sick with all kinds of bacterial nasties.

Genny, Thanks for the link. I was able to open it and it is talking about allergy injections. Here is the part of the Federal regulation on vaccines that it was referencing:

Products in multiple-dose containers shall contain a preservative, except that a preservative need not be added to Yellow Fever Vaccine; Poliovirus Vaccine Live Oral; viral vaccines labeled for use with the jet injector; dried vaccines when the accompanying diluent contains a preservative; or to an Allergenic Product in 50 percent or more volume in volume (v/v) glycerin.

Here is a quote from the FDA about cosmetics which states that a cosmetic containing more than 10% glycerol is self preserving:

Some cosmetics, i.e., those containing more than about 10% ethanol, propylene glycol, glycerol, etc., and cosmetics in self-pressurized containers, are self-preserving and are not likely to become contaminated with microorganisms.

So, i guess i am still wondering where the information came from that all products containing glycerine need a preservative because it attracts water and is a sweetener. I am personally back to this; I dont believe the products the OP asked about which would not normally support bacterial growth would with the addition of 10% glycerine. If they wouldnt support growth without glycerine, there is no reason they would with a little added in.

 

[Genny]

So, i guess i am still wondering where the information came from that all products containing glycerine need a preservative because it attracts water and is a sweetener. As far as i can find, this is incorrect. So i guess, im personally back to this; I dont believe products the OP asked about which would not normally support bacterial growth would with the addition of 10% glycerine. If they wouldnt support growth without glycerine, there is no reason they would with a little added in.

Those products without glycerine wouldn't normally support bacterial growth because there's no water in them. But when you add glycerine, glycerine can attract moisture/water into the product. That's where the bacteria will grow, is in that water, not in the glycerine.

It has nothing to do with the fact that it's a sweetener, it's the humectant part that's the problem.

 

[Genny]

P.S. I'm doing a small experiment with shea butter & vegetable glycerin. I just started it yesterday, so I'll see how it goes.

 

[bodhi]

Those products without glycerine wouldn't normally support bacterial growth because there's no water in them. But when you add glycerine, glycerine can attract moisture/water into the product. That's where the bacteria will grow, is in that water, not in the glycerine.

It has nothing to do with the fact that it's a sweetener, it's the humectant part that's the problem.

Agreed about bacteria sometimes being able to grow in water, but just because it can grow in water does not mean that it will. Glycerine is an alcohol and binds its own weight in water, and even if it didnt, in the case of a bath bomb, the salts and citric acid would prevent any growth, and in a lip balm, the oils or butters would.

If the logic is that adding a humectant to a product will cause bacterial growth, then any product with salt or propylene glycol would need an additional preservative because even though they are preservatives, they are also humectants. And in the same line of thinking any product that is a humectant including the salt and sugar in everyones kitchen needs a preservative because it is drawing water out of the air and growing bacteria.

So even if you ignore the FDA, and the pharmaceutical industry, it just isnt sound logic, or science.

 

[bodhi]

P.S. I'm doing a small experiment with shea butter & vegetable glycerin. I just started it yesterday, so I'll see how it goes.

Let us know how it turns out.

 

[Genny]

Glycerine is an alcohol and binds its own weight in water, and even if it didnt, in the case of a bath bomb, the salts and citric acid would prevent any growth, and in a lip balm, the oils or butters would.

Most bath bombs don't have salt in them, just baking soda, citric acid & something wet to hold them together. Also, bath bombs that contain citric acid absolutely do grow mold on them due to humidity.
http://www.soapmakingforum.com/f19/what-happened-1988/
Plus, the company Lush is notorious for having moldy bath bombs.

I just read this afternoon that at 45% glycerine can lower the water activity of a product. I can't remember where I read it, I think it was on aqualab. But that would be way too much glycerine for a lip balm or bath bomb.

But another problem with adding glycerine to lip balms is that it doesn't incorporate into oil/butters without using an emulsifier, which most people don't do. So, it just seeps out. Even if it doesn't seep out right away, it will over time.

That's fine if you think that non-water products don't need a preservative. Then don't add them to your products.
I'm going to stand by my opinion that if you add a humectant to a product, add a preservative. I'd rather not take the chance of someone getting staph infection.

 

[bodhi]

I cant comment on the thread or lush because I dont know how they were made or if ingredients may have been contaminated or any number of things, but baking soda is a salt and it kills mold so that is rather interesting.

I dont think i said that products that dont contain water do need or dont need a preservative. My comments were that if the material didnt need a preservative to begin with, then the addition of the glycerine wouldnt change that-because glycerine is a preservative.

Yes, glycerine lowers water activity. Decreased water activity equals decreased microbial potential equals preservative. I think its in lunch meats at 1 or 2%.

Anyway, hope your lip balms turn out nicely.

 

[Lindy]

Bodhi since you seem determine to prove your science, perhaps you can share you background with us that gives you this knowledge. You're rather new to the forum and we haven't yet had the opportunity of getting to know you.

 

[Pink]

Such great info! Thank you Bodhi, Genny, and Melstan for all your insight and helpful information.

I actually do add in some salts with my bath bombs as well as the citric acid, soda, etc. I've never heard of a bath bomb growing mold, but I'm sure depending on where its stored and how its made, it certainly could eventually. I'm just wondering on that post if they were experiencing "warts" from the reaction of high humidity.

IDK, anyway back to the glycerin. I did happen to read for a couple hours on the craftymonkey blog the other day. I did find two small areas where she stated to add a preservative. One was a recipe she had written down and stated that since there's water activity in it, that it would need a preservative. The recipe didn't have water as an ingredient, so I'm assuming she meant the glycerin that she had written down as the ingredient. The other was a reply to a post. Someone had written down their recipe that contained water and glycerine. They asked her if they was to replace the water with something else, would they still need a preservative. Which she replied yes because it contains glycerine. Thats just in two small sections that I happened to catch and she doesn't really go into detail about it being added in smaller amounts in products without water.

I did also send a message to the lovely ladies over at soap queen. I did get a response back that they would recommend adding a preservative since it is a humectant. But then again I had seen back in their older blogs, they still have a recipe up for a lip balm which contains glycerine without an added preservative. Even though they later commented on that exact recipe that the glycerine didn't mix in real well.

Then I find this... http://www.diycosmetics.com/pages/Are-Preservatives-Necessary.html Where it states "GLYCERIN: glycol will also bind to the water making it unavailable to microorganisms". Which is what I had pretty much gathered from several resources before, when I decided to add glycerin in some of my products. Also when buying some premade glycerin pigments to be added in different products (which a lot of us do) and not hearing anything about needing a preservative when adding those into products.

There is all sorts of conflicting information out there thats making my head spin :crazy: Normally when I do research on things like this, you can always sort out the not true, and the true. On this subject I can't. It might just be one of those things that you can argue about til your blue, and just have to make your own "personal" decision. Or just simply have to take your own action into getting a recipe tested to find out.

I may next week contact the FDA about their website talking about using 10% glycerine, and see what they have to say. If they even will give me any helpful info.

Genny, I'm definitely curious on the shea butter and glycerin experiment. Was you planning on testing it with a home kit? And if so, can you tell me what you use?

 

[bodhi]

Bodhi since you seem determine to prove your science, perhaps you can share you background with us that gives you this knowledge. You're rather new to the forum and we haven't yet had the opportunity of getting to know you.

It isn't My science Lindy, it is Science. There is no need to prove it as this has already been done by the medical, pharmaceutical, food service and cosmetic industries. The information is available to anyone interested in educating themselves beyond what is offered by a biased salesperson.

My background is irrelevant, but since you asked, it's in Medicine. What is yours?

 

[DeeAnna]

I have been following this thread with some interest, but I have to say the conversational tone is now beginning to feel rather unkind and unhelpful. I think it might be best to allow this discussion to expire with as much grace as can be managed at this point. --DeeAnna