Saturday, October 17, 2009

A more in-depth look at anti-oxidants!

Anti-oxidants can stave off rancidity in our oils, giving them a longer shelf life in our products. Nothing can make the possibility of rancidity go away completely, but anti-oxidants are huge weapons in our fight on ickiness!

Free radicals are constantly running around in our lotions, seeking out electrons to fill its valence shell. When we add an anti-oxidant, we provide that free radical with those electrons. The radical is content with its electron shell and bothers us no more! How awesome is that?

VITAMIN E is one of the main lipophilic anti-oxidants you'll find for bath and body products, and it's the most commonly used by homecrafters. It comes in four varieties of tocopherols and four varieties of tocotrienols. We will be focusing mainly on the alpha tocopherol, which is the one you're most likely to see in suppliers' shops.

Vitamin E is found in our stratum corneum and is secreted by our sebaceous glands to the surface of our skin. Studies have demonstrated - at least on lab rodents - that it sinks readily into our skin and can inhibit lipid peroxidation, which is like oxidiation of the oils on our skin! It has also been shown to reduce sunburn irritation in mice (which just shows you albino creatures and sunlight don't mix!).

The interesting thing about Vitamin E is it can lose its anti-oxidating power, so it's unable to contribute an electron to the free radical. But in an exciting redox process, it gets its electron back, so the cycle continues again. Ah, you have to love chemistry!

You can use it at rates as low as 0.01 to 0.05% in your creations or oils. I like to use it at 1% because it has such wonderful qualities for skin, but you can use lower amounts.

VITAMIN C, or ascorbic acid, is one of the most common hydrophilic anti-oxidants. It's present in high amounts in our skin, and it can chase away scurvy (arrr, be gone scurvy!). Unfortunately, it's not very stable and can be esterified with phosphates.

For our purposes, it works well with iron found in our water, specifically converting Fe(III) to Fe(II).

Honestly, although Vitamin C does have some nice properties for skin, given its instability, it's probably not the anti-oxidant to use most in a lotion. As well, it's hydrophilic, meaning it's going to hang out mostly in the water section of the lotion, and rancidity takes place in the oil part of our lotion.

Join me tomorrow for fun with the chelating agents - EDTA and citric acid!

10 comments:

Mich said...

Hi Susan,
Great topic! Question:

I know some people put Vit E into their oils right after they get them to extend shelf life. Do you recommend this? If so, what percentage would you use?

Also: Do you think that there is much difference between using an d-alpha tocopherol from a soap supplier and from the health food/grocery store? Is a blend like Covi Ox T 50 worth the extra money?

Thanks!

Susan Barclay-Nichols said...

Hi Mich! I think it's a great idea - I've always mean to put the Vitamin E in the oils when I get them, but I always get so excited to formulate, I forget!

Something like Covi Ox T 50 has 50% tocopherol, which means 1 gram contains 0.5 grams tocopherol. For this product, it's recommended at 100 to 400 ppm (or 0.01 to 0.04%) for unsaturated oils, so you'd want to add 0.1 to 0.4 grams per kilogram.

It's recommended at up to 2000 ppm (or 0.2%) for polyunsaturated oils (something with a really short shelf life, like hemp seed oil) so you'd want to add 2 grams per kilogram.

Make sure the Vitamin E from the store is tocopherol and not tocopheryl acetate. If it is the tocopherol, then you're fine - the acetate one is not an anti-oxidant for the purposes of retarding rancidity in your oils!

Thanks for posting this comment. This really should have been included in the post...oh well, I'm allowed to forget things some times, eh?

Anonymous said...

I've read that many antioxidants are light sensitive. They will quickly become inactivated with exposure to light. I know vitamin c is like this. That's why c serums have to be packaged in opaque or amber bottles. I have read that vitamin e is also light sensitive. So then why is it that I keep seeing vitamin e oil for sale in clear bottles? Was I misinformed about vitamin e being light sensitive? Or are the companies that sell vitamin e oil in clear packaging gypping their customers? Or are there some other factors at work or information I'm not aware of?

Thanks,
Bridget

Susan Barclay-Nichols said...

Hi Bridget! I've tried to answer your question in today's Weekend Wonderings. The short answer is that although Vitamin E is light and heat sensitive, it's not so sensitive that we can't expose it to light ever. Think of it as being on par with our oils - we want to store them in a cool, dark place!

Yuong said...

Hi Susan, just started reading your blog and loving it. So much information to process.

Question for you. What is the benefit of using Vitamin E in coconut oil vs powder Vitamin E in our DIY? I try looking on line and also gone through your blog to see if it has been covered but do not see it.

Bye Yuong

Susan Barclay-Nichols said...

Hi Yuong! I have never seen or used powdered Vitamin E, so I can't offer any advice. Sorry!

Anonymous said...

Thanks for the tip on using Vit E for increasing the life of my products. I'm a bit confused about shelf life of oils, is this the life of the product once it is made or is it the how long the oil will last before you make your product??

Thanks again for your excellent advice

Steve

Susan Barclay-Nichols said...

Hi Steve. There's a whole section on shelf life in the FAQ, if you want to learn more!

NICOLE KENMILLE said...

Thank you for this. I am loving all the wonderful information in your blog! I was under the assumption that the tocopherol acetate could also be used because some supply websites specifically sell only this type and say it is for exactly this. I have been using this because I seen it in some recipes on the Internet too.ive been using one called sundown Naturals vitamin E and the INCI says tocopherol acetate. Hmm I wonder if this is part of why the rosehip facial moisturizer I made didn't do very good. I used liquid Germall Plus and this specific vitamin e and it seems to have an off smell after a couple weeks so I quit using it. I was bummed because it worked so well on my face that seems to be oily and acne prone but has dry spots as well. I will have to try again with the correct antioxidant!! I hope your having a good day and again I appreciate all your hard work in this blog and I love the fact that you are doing stuff to help teach kids about things! That is something I want to do myself where I live there is nothing for kids to do and they tend to get into the partying and we have had so many overdoses recently it is sad. Our tribe says they are for the kids and they are our future but they do not provide much for them. Anyway I'm rambling on lol. Have a good day��

Susan Barclay-Nichols said...

Nicole, if you ever want to set up some groups for the kids in your tribe, let me know as I have so many hand outs and lesson plans and ingredient/supply lists for so many different crafts. Consider a board/card game night as a way to connect with youth. We've been running ours for 11 years, and we still get a full house every month!