The words “supercritical CO₂ extraction” didn’t cross my lips until I heard about the trending (and incredibly helpful) CBD oil – but more about that in an upcoming article. As it turns out, it’s the same process that separates caffeine from coffee beans– decaffeinating them and giving us decaf coffee as a less intense alternative. It’s often used in pharmacology to extract medicinal constituents from plants – and in cosmetics, supercritical CO₂ extraction may be the most effective way to extract the highest quality oil.

Extracting oil directly from a fruit, seed or any oil-bearing plant will produce a more concentrated potency. Think about all the nutrients, antioxidants and useful properties of any given raw material being compressed down into a singular, liquid tincture. This is what extraction does – and has been doing for over a millennia.

Not all extractions methods are equal

There are a range of extraction methods, some which produce a higher quality of oil than others. Two popular, effective & environmentally friendly processing systems are cold-pressing and supercritical CO₂ extraction. Both are well-practiced and consistently used across many industries – but admittedly, one is superior than the other. Particularly when it comes to the more fragile oil types that are typically present in cosmetics.

What does “cold-pressed” mean?

Cold pressed oils are collected by crushing a plant or seed with a large screw. This is one of the best ways to derive a nutrient-dense juice from fruit & vegetables. When it comes to oils however, it can become too destructive – simply due to the nature of the system. Cold-pressing allows oxygen molecules to enter throughout the process. And oils lose their quality when exposed to oxygen¹, which also reduces their shelf-life.

The cold-pressed method may also utilize heat. Contrary to its name, when it presses an ingredient with a hard shell, like the rock-like characteristics of rosehip seeds, the friction of the machine raises the temperature. This is a problem for heat-sensitive oil – like rosehip oil – as it may also lead to oxidation² and further reduce its shelf-life.

Supercritical CO2 extraction

Supercritical CO₂ extraction is a completely closed system, wherein the raw materials are compressed down by the pressure of CO₂ gas & fluid. Unlike with the cold-pressed method, the oil is extracted without coming into contact with oxygen during the process. Some low heating is used, but it is cooled again before pumping the liquid. But above all, supercritical CO₂ extraction can extract beneficial constituents⁴ – such as beta carotene in carrots, or flavonoids in the rosehip fruit & seeds. So the end product is a purely concentrated liquid extract that retains all the natural benefits, preserves the best colour, and has the longest shelf-life possible. It’s the next best thing to fresh.

Superheroic use of supercritical CO₂ extraction in cosmetics

As a brief summary, the primary benefits of supercritical CO₂ extraction in cosmetics are as follows:

• Limited rancidity – no pre-exposure to oxygen means reduced chances of spoilage, so the product and its benefits keep for as long as possible
• Stability – fragile oils are a higher quality when extracted with low or no heat
• Selective process control – obtaining constituents that hold the best healing properties, adding to its effectiveness
• Environmentally sound – using carbon dioxide (a natural byproduct of human existence) for pharmacological & medical practices is a completely natural and safe method for oil extraction

Naturally, there is a growing demand to use supercritical CO₂ extraction in the cosmetic industry. It ensures the freshness of flavour, colour & odor – as well as quality, especially when used to create oils which are highly susceptible to oxidation & rancidity⁶. While other extraction methods are competitively comparable, they cannot all be rated equally. And how oils are manufactured is essential to how the product will hold up – both on the shelf and on the market. At the end of the day (or at the end of a product’s shelf-life rather), it’s worthwhile to know if your product will still reap the same benefits. So take that bit of extra time to really know your products, the ins & outs of how they’re being made – conscious consumption is the way to go ?

Resources:
1. The Role of Oxygen in Lipid Oxidation Reactions: A Review
2. Mechanisms and Factors for Edible Oil Oxidation
3. Characterization of canola oil extracted by different methods using fluorescence spectroscopy
4. A Step Towards Sustainable Chemistry
5. Extraction Methods
6.Comparision Of Conventional And Supercritical Co2–extracted Rosehip Oil

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Photo credit: @syn_thesis