Not All Oils are Created Equal
With the recent craze around face oils, many beauty users have made the conscious decision to include oil as a part of their daily skin care routine. Natural oils and butters have gained a very positive image in consumers’ minds because they can combine the efficacy of botanical extracts and the functional benefits of emollients. This craze is felt all around the world, and specifically in Asia, where the number of Beauty and Personal Care products launched using natural oils and fats has increase 17% annually over the past five years.
Oils and fats are traditionally defined as “a group of natural esters of glycerol and various fatty acids”, which will respectively be liquid or solid at room temperature. When consumers experience these natural compounds in a formula, they will consider many factors: greasiness, spreadability, play time, after-feel, film-residue, etc. Many of these characteristics are driven by the chemical composition of the ingredients in the oil phase: length of triglycerides chains, degrees of saturation, functional groups, etc. Overall, triglycerides tend to be associated with a greasy feel, requiring them to be blended with drier components in order to remain pleasant when applied.
Jojoba oil is a notable exception. While traditional oils, from avocado or sunflower for instance, are composed of triglycerides, jojoba oil is composed of straight, unsaturated esters, also known as liquid wax esters.
This sets jojoba oil aside from the other natural oils and impacts its sensorial profile. Jojoba oil is well-known for its exceptional comfort, smooth application, good absorption, and immediate moisturization. As a matter of fact, this unique jojoba liquid wax ester shares structural similarities with human sebum when it comes to composition. This proximity explains jojoba oil’s activity and compatibility with human skin.
Why Chemical Structure Matters
From a chemical stand point, jojoba oil is less susceptible to oxidation than the triglycerides present in traditional oils. Moreover, jojoba oil is a natural source of anti-oxidants, such as tocopherol and other primary and secondary metabolites. These two attributes combined make jojoba oil one of the most stable natural oils on the market. Natural triglycerides contain double bonds that are very prone to oxidation, leading to degradation, which will ultimately alter its color, odor and functionality. Exposure to heat or light can accelerate this chemical process. Resistance to oxidative degradation can be measured by calculating the Oxidative Stability Index (OSI). When comparing jojoba oil to common natural oils, the OSI of jojoba oil is at least two times superior, meaning that jojoba oil is twice as resistant to rancidity in the conditions of the test. Compared to avocado oil, this ratio jumps to five! While many factors will influence a formulation’s stability, working with ingredients that are less likely to oxidize certainly helps, and jojoba’s stability could prove critical in bringing formulations with long shelf-life to the market.
Toughen Up your Formulations!
Working with natural oils can be a tricky job. As previously mentioned, most triglycerides have a proclivity for oxidation and hydrolysis, leading to dramatic quality issues over time and potential poor consumer experience.
New data shows that the addition of jojoba oil to popular, yet less stable, oils and butters increases the overall Oxidative Stability Index of the blend. This means that formulators can use jojoba oil to easily incorporate and protect more sensitive natural oils and active ingredients in their formulations.
This contribution to higher oils and formulations stability could be leveraged to make formulating with sensitive ingredients easier. Over the past few years, to satisfy consumers’ appetite for novelty ingredients, many new botanical oils have started to be used more commonly than before, but very often these oils demonstrate poor stability. For instance, sesame oil and hemp oil are known for their short shelf life and heat sensitivity. Combining them with jojoba oil can drastically help decrease the risk for premature oxidation and ensure a better quality of the finished product.
These studies demonstrate that jojoba oil is not only skin’s best friend, but also a formulator’s key ally into developing elegant, stable and active formulations.