Monday, January 6, 2014

What do you want to know? What's up with walnut oil?

In the What do you want to know? post, Nicole asks: I have been searching for reliable information on Walnut Oil, and am wondering if you have formulated with it or have a good source that I could use? My goal is to find out what its components are and what it can do in a product, similar to what you have pulled together in your chart, but I'm having no luck finding that kind of detail. 

Walnut oil (Juglans regia oil) is high in unsaturated fatty acids with a fatty acid profile of palmitic acid (C16:0) at 5% to 11%, stearic acid (C18:0) at 2% to 5%, oleic acid (C18:1) at 16% to 28%, linoleic acid (C18:2) at 48% to 59%, and linolenic acid (C18:3) at 5% to 16%. We know oleic acid is great for softening skin, regenerating skin cells, moisturizing, and behaving as an anti-inflammatory. Linoleic acid helps restore skin's barrier function and reduces transepidermal water loss (TEWL).

Walnut oil has 1.8 to 3.0 mg per gram phytosterols (1.8 grams to 3.0 grams to 1 kg of oil), with most of it composed of sitosterol. It contains between 268.5 ppm to 436 ppm Vitamin E. I couldn't find anything about the polyphenols in the oil, but there are phenolic acids and tannins in the nuts, which might be why walnut oil is a drier feeling oil.

It has a fatty acid profile like hempseed oil and as much linoleic acid as grapeseed oil. This means, unfortunately, it's going to have a short shelf life, something like 3 to 6 months maximum. (I'd consider it at 3 months).

I need to make a comment about the shelf life. I have seen references to walnut oil having a shelf life for a year, but from a chemistry perspective, I can't see this working. It has a ton of linoleic acid but not a lot of Vitamin E, so it'll go rancid pretty easily. This study shows it has a shelf life of less than grapeseed oil, which is 3 to 6 months maximum. ("...the predicted shelf-lives were significantly lower than that of the storage times, especially, walnut oil (very prone to oxidation) gave 15-20 times lower shelf-life than the best-before storage life.") I've seen a variety of shelf lives discussed, including up to a year, but there was the suggestion that the oil be kept in a cool dark place or the fridge to get a year, and we aren't going to be doing that with our lotions, so I feel very comfortable in saying that we should consider it to have a shelf life of 3 months. 

I tried it neat on my skin and it felt as if it had sunk in pretty quickly. I'd say it feels like grapeseed oil, hazelnut oil, or macadamia nut oil, but with more linoleic acid than the latter two. It's a very very pale yellow, and it's got a watery consistency, very thin.

It has a nutty taste - not applicable for our bath & body products, but significant when you're making a nice oil and balsamic vinegar dip for your foccacia bread - and a bit of a nutty smell.

Analysis of free and esterified sterols in vegetable oils
Fatty acid and tocopherol contents of walnut oil
Shelf life: Garden of Wisdom
Shelf life: The Soap Queen (3 months)
Nut composition and their health benefits

The picture of the tree in the snow is the picture of the walnut tree in my backyard. Raymond and I were married under that tree, and I just love it! 


Anonymous said...

Thank you very much! i appreciate your research! I bought a bottle a month back so i'd better hurry up and use it.
- Nicole

Veronique said...

I LOVE walnut oil. I put it in my body butter recipe along with avocado oil and it's so moisturizing and my skin absorbs it right away and it's never greasy. Funny thing, i'm dearly allergic to avocados, and my brother to all nuts, and we can both use this product without any reaction at all!!