To extract oils from foods, there are varying methods that can be used. These consist of either a chemical process or a mechanical one. You’ve probably heard of cold pressed or virgin oils touted around, but what exactly does it mean? And why is it good? Cold pressed is exactly like it sounds like, the oils are squeezed out without the use of heat. They are normally extracted through use of an expeller, at a controlled temperature below 49C. Keeping the oils under a certain temperature ensure its nutrients stay intact, and aren’t subject the the chemical changes heat brings. This is the reason why a drizzle of extra virgin olive oil over your salad is healthy, but deep fry some potatoes in it and it becomes an unhealthy(yet delicious) snack.
Heat extraction of oils is are also mostly done via pressing, but often done via adding heat to roast the seeds. Heat extraction can also be done via chemical extraction which is done through hydrogenation, solvent extraction, deodorization, or occupational exposure. Solvent extraction produces more yields than pressing, and is done via petroleum derived solvents.
Most of the oils available on store shelves are obtained via heat extraction. The main reasoning being it’s higher yields and cheaper price point. These oil are often further refined to remove impurities, taste, and to stabilize the fatty acid. Cold pressed oils by contrast have low acidity, making refining unnecessary. The oils also have much more distinct, and stronger flavours.
When oils are heated they release high concentrations of aldehydes, this is a chemical that is linked to cancers, dementia, and heart disease. Heating can also cause the release of dangerous free radicals. Differing oils can withstand heat at varying degrees, so while some oils should be kept out of high heat, others fare better. Each oil has a smoke point, which if exceeded the oil then starts to break down and become dangerous. Here are a list of oils and their smoke point, the higher the smoke point the better it is for frying. This will ensure your oil doesn’t go rancid and become harmful.
- Butter: 177C
- Canola oil: 204C
- Coconut oil: 177C
- Extra virgin olive oil: 210C
- Flax oil: 107C
- Grapeseed oil: 204C
- Light olive oil: 242C
- Safflower oil: 232C
- Sunflower oil: 226C
Cooking, and/or eating is a major part of our lives that are dependent on oil. You should always opt for cold pressed as it’s nutritionally, and taste better to boot. Similar principles apply when opting for oils in skincare products. High quality cold pressed oils simple contain more of the anti-oxidants, vitamins, and minerals, making this choice a no-brainer.