Thursday, December 18, 2014
Ingredient: Watermelon seed oil
It contains 11% palmitic acid (C16), 10% stearic acid (C18:0), 15% oleic acid (C18:1), and 63% linoleic acid (C18:2).
It has low tocopherol or Vitamin E content at 63 ppm (solvent) or 73 ppm (expeller), but high phytosterol amounts at 8140 ppm, with the main one being stigmasterol. (It has 1.5% unsaponifiables, which is where we find the phytosterols.) It has an iodine value of 115 to 125 and a saponification value of 190 to 198, although I saw it listed at 183, so please check with your supplier before soaping with it. Its specific gravity is 0.85. It contains lycopene, which is a very powerful anti-oxidant.
I've seen it listed as having a two year shelf life or "stable", but with high unsaturated fatty acids and low Vitamin E, I'm a little dubious about this. It does have lycopene, which is a better anti-oxidant than tocopherols, but I couldn't find how much. In my workshop, I'm considering it to have a six month shelf life until I see something more solid.
I've seen this oil called a cleansing oil because it can dissolve sebum, but I've been unable to confirm this property. I've also seen water melon oil listed as a non-greasy oil. If we consider soy bean oil or sunflower oil as very greasy oils, and hazelnut oil or macadamia nut oil as non-greasy feeling oils, I would say this is not as non-greasy as hazelnut oil but not as greasy as soy bean oil - let's call it "slightly greasy". I thought it felt like it formed a nice moisturizing layer on my skin that was still there an hour later. I definitely wouldn't describe it as "sinking in" to my skin. (Please share your thoughts about the greasiness level!)
This is a more expensive oil - I've seen it for $12.50 for 2 ounces at the Formulator Sample Shop, $9.05 for 1 ounce at the Garden of Wisdom. It is suggested to use it at 1% to 10% in your products, but it is safe to use neat at 100%. I'd say it has a shelf life of 6 months, but your mileage may vary.
Antioxidant and cytotoxic effects of seed oils from edible fruits
Characterization of crude watermelon seed oil by two different extractions
Phytosterols and steryl esters in diverse Curcubita, Cucumis and Citrullus seed oils
Extraction and determination of physico-chemical properties of watermelon seed oil...
Book: Lipid Handbook
Join me tomorrow as we take a look at using this interesting oil in an emulsified sugar scrub!