Are All Oils Essential? Are Essential Oils Even Oils?

Originally posted here: https://mcgill.ca/oss/article/health-you-asked/are-all-oils-essential-are-essential-oils-even-oils

Oils are defined as any net uncharged chemical substance that is a thick liquid at room temperature and is both hydrophobic (does not mix with water) and lipophilic (does mix with fats, or lipids). When we think of them, our minds tend to focus on the kitchen: olive, canola or peanut oil. But there are also oils in your garage (motor oil), bathroom (conditioner) and your art collection (oil paints).

Animal and vegetable oils are a mixture of triglycerides. A triglyceride is just three fatty acids held together by a molecule of glycerol, and they can be saturated or unsaturated. Saturated fats have the maximum number of carbon-hydrogen bonds, where unsaturated fats contain extra carbon-carbon bonds. These double bonds give unsaturated fats lower melting points, because the double bonds put kinks in their strands, preventing them from stacking nicely on each other.

Practically, this means that oils made mostly of unsaturated fats are liquids at room temperatures (like olive oil), and oils made mostly of saturated fats are solids (more commonly referred to simply as fats, like cocoa butter or lard).

So what about essential oils? The name is a bit misleading, since they aren’t oils in the classic sense, and aren’t essential in the same way essential amino acids are. They are hydrophobic, but unlike animal and vegetable oils, are not made of fatty acids. Their composition instead depends heavily on what plant it originated from. The “essential” in their name refers to the fact that the oil contains the essence of a plant, its fragrance.

Essential oils are often extracted via distillation (as shown in the infographic), but can also be physically squeezed out of some plants (like orange peels) or, in the case of flowers, extracted with a nonpolar solvent.

It’s easy to forget amid the many baseless health claims made for essential oils that they do have real purposes. Some, like clary and lemon oil, are used for flavouring. Others are used primarily for adding fragrance to cosmetics, foods or your home via a diffuser. Clove oil is used for euthanizing fish in labs, orange oil can repel ants, and eucalyptus oil is commonly used in cold remedies like vapour rub.

But just because most essential oils don’t help your health doesn’t mean they’re innocuous. Many are very flammable, with flashpoints as low as 50°C, others are photosensitizers and can make your skin more vulnerable to sun damage. Contact dermatitis from essential oils is fairly common, and there’s growing evidence that they can also affect hormone balances, particularly in young males. Several essential oils (including tea tree oil) are toxic to domestic animals, and while humans run little risk of achieving a toxic dose of most essential oils, there are exceptions. Cassia oil, derived from Chinese cinnamon, requires only 0.3 ml per kg of body weight to achieve dermal toxicity. That means that only 17 mL (little more than a tablespoon) of the oil applied to the skin could have tragic consequences.

So, all things considered, I’ll keep my vegetable oils for cooking and my essential oils strictly for smelling. Though I have always thought that coconut oil smells pretty nice.

Did you know that tigers and jaguars are attracted to the scent of Calvin Klein’s Obsession for Men?

Originally published here: https://mcgill.ca/oss/article/did-you-know-general-science/tigers-and-jaguars-are-attracted-scent-calvin-kleins-obsession-men

This surprising fact was initially discovered by researchers at the Bronx Zoo who compared twenty-three different perfumes’ abilities to attract tigers’ attention. One of the least successful was Estée Lauder’s Beautiful which kept cats occupied only for 2 seconds. Revlon’s Charlie worked for 15.5 seconds, Nina Ricci’s L’Air du Temps for 10.4 minutes, but the clear winner was Calvin Klein’s Obsession for Men which kept the cats concentrating on it for 11.1 minutes. 

It turned out that the zoo researchers weren’t the only ones interested in attracting big cats to specific locations. Field researchers in Guatemala and Nicaragua have started using the perfume to attract jaguars to their field cameras. The scent entices the cats to rub their chin and cheeks on whatever item has been sprayed. Scientists are then able to grab the hairs left behind for research purposes. 

The reason cats are crazy for this eau de toilette is thought to be civetone, the compound used to achieve its characteristic musky smell. Civetone, the smelly component of civet oil, is the pheromone of the African civet, a cute little animal native to the woodlands of sub-Saharan Africa. Once upon a time, civet oil had to be extracted from the perineal glands of the creatures, but thankfully nowadays it can be synthesized from palm oil. 

Why Do Old Books Smell So Good?

Originally published here: https://mcgill.ca/oss/article/did-you-know/why-do-old-books-smell-so-good

E-readers might be convenient, but they’ll never have that comforting old book smell. It turns out that the smell of old books is due to the organic materials in books (like cellulose from wood pulp) reacting with light, heat and water, and over time releasing volatile organic compounds or VOCs. What VOCs are released depends on how the book was made and stored, but common scents are toluene or ethylbenzene, which smell sweet, benzaldehyde or furfural, which smell almond-like, or vanillin, which smells like- you guessed it- vanilla. Book VOCs are even being used to date old books, as the rate at which they break down can be used to determine the age of some old tomes.