Shea is the most used plant-based butter in cosmetics. Chances are you are already formulating with shea, but can you truly claim to be a shea master? This is the challenge we put to visitors to In-cosmetics, who we invited to complete a quiz to prove their shea knowledge. You can test yours here now!
The truth is that shea butter is widely used and appreciated in cosmetics, but it still poses frequent challenges to formulators. This became even more apparent in February, when during our webinar: Mastering Shea - overcoming common formulation challenges hosted in UL prospector, we received over 60 questions. Watch the webinar here, or read about it here.
So, would you like to know what the top five myths and truths were relating to shea, that we uncovered with our quiz?
Here you go…
1. A stick formulation using shea butter is best cooled in a freezer.
2. Shea butter is best combined with coconut oil for the best skin feel
This is false! The triglycerides/fat-molecules in coconut oil and shea butter differ in chain length and are therefore not very compatible when solidifying. The long C16/18 chains in shea butter don’t want to integrate in the short C12/14 chains the coconut oil crystal structure and vice versa, which increases the risk of crystallization issues. When working with coconut oil you are better off combining it with liquid shea butter, canola oil, or sunflower oil, or with short chain solid fats such as palm kernel oil.
Figure 1. 40% Refined shea butter + 60% Hydrogenated coconut oil (left), 40% Liquid shea (LIPEX 205) + 60% Hydrogenated coconut oil (right). Samples were exposed to alternating temperatures of 20°C and 30°C (12h cycles) for 4 weeks.
You can read more about liquid shea here
3. Shea butter can go rancid over time impacting the final formulation
This is true! Shea butter can go rancid when exposed to heat, air, or light and its shelf life is highly dependent on its quality. This is determined by the amount of free fatty acids and contaminants it contains, as well by as its processing. An oxidized butter can impact the color and texture of the end formulation, as well as the skin.
The Oxidative Stability Index (OSI) is a good measure of a product’s resistance to oxidation, while Peroxide Value (PV) is a good indicator of the state of oxidation.
AAK’s LIPEX Shea has an OSI that is over two times that of a typical refined shea butter, and its peroxide value develops slowly. This results in LIPEX Shea having three years of shelf life, versus one to two years for a typical refined shea butter.
4. Shea butter does not have a melting point, it melts over a temperature range
This is true! Shea butter melts over a temperature range and has a melting profile, rather than a specific melting temperature. Understanding the melting profile of an emollient is important, since it will indicate how the ingredient will behave in a formulation, on the skin and in the jar.
It is usually represented by a curve that indicates the amount of solids (solid fat content) as a function of temperature. The solid fat content affects the texture, skin feel and thermal stability of skin care formulation.
You can read more about how to read melting curves here
5. Shea butter can’t be used in hair care applications
This is a myth! Shea butter is excellent for hair care, providing moisture, sealing in hydration, and reducing frizz. With an increasing focus on the scalp and the skinification of haircare, it is also increasingly being used for scalp treatment. It might be interesting to also consider liquid shea butters for these applications, including LIPEX SheaClear for clear hair oils and serums. Check the formulations below for inspiration: