Did you ever find an old oil bottle in your pantry that looked especially dark and smelled really odd?
Well, congratulations! You just bumped into a rancid oil…
The process of rancidity
Oils, Like any other organic matter, go bad with time. In oils, it’s the rancidity process that gets them to smell very bad which makes them practically unusable.
Every oil comprises of a chemical structure that contains what’s called “Double-Bonds”. Without getting too technical, this chemical structure, which is part of the oil composition is very sensitive to oxygen. Introduce Oxygen and these Double-Bonds in the oil repeatedly, and you’ll immediately cause these delicate Double-Bonds to slowly “break”. The more Double-Bonds break within an oil, the more rancid it becomes.
So, if this “breaking” process is so bad, can we stop it somehow? Unfortunately not. This process is unstoppable, but we can always take specific measures to slow this process as much as possible.
Other causes of rancidity
As we said earlier, exposing oil to oxygen is the main reason for rancidity. But besides that, heat is also a process that speeds up rancidity. The hotter or, the longer you heat oil, the shorter its shelf life will become!
Also, believe it or not, light is another cause for speeding up rancidity in oils. Light breaks up Double Bonds as well, and the more the oil is being exposed to light, the faster the rancidity process. That’s why the best way to ensure an oils longevity is to protect it from air, heat, and light, very simple and easy to apply. But what else? Are there other measures we can take to slow the rancidity process?
Fighting rancidity with antioxidants
Here come the antioxidants for the rescue!
In a nutshell, antioxidants fight rancidity in a way that prevents the “harmful” external molecules from breaking our beloved Double-Bonds. Well, actually not stop altogether. As mentioned earlier, rancidity is an ever going process. But the addition of antioxidants to an oil mixture slows rancidity in a significant way.
Two types of antioxidants
In our arsenal as skincare formulators, we have two ingredients that can help us preserve our oils. One is Vitamin E. It is a very popular antioxidant, and you will find it a lot in everyday cosmetic products. It’s absorbed to the skin quite fast and has some exciting benefits. It moisturizes and softens the skin, and it can reduce the appearance of scars as well.
The second ingredient is Vitamin C.
Vitamin C, or ascorbic acid, is the celebrity of Vitamins. Besides the long list of benefits Vitamin C has on the skin, such as boosting the skin’s collagen and fighting free radicals, it can also shield oils from going rancid. Unfortunately, due to its chemical instability, this is not the ingredient we will use for our oil mixture. We love you anyway Vitamin C 🙂