About Essential Oils
Essential oils are naturally occurring aromatic compounds that are found in the seeds, bark, stems, roots, and flowers of plants. The type of volatile aromatic compounds present in an essential oil determines both the oil’s aroma and the benefits it offers. Sound too scientific? Not to worry -- Vitruvi cofounder and CEO Sara, first became interested in the science behind scent when she was in medical school learning about how different scents register in different parts of the brain. Read below to learn about how the oils are extracted and the science behind what makes us respond to scent in different ways.
Most common essential oils—such as lavender, peppermint, tea tree oil, and eucalyptus—are team distilled in order to extract their oils. In order to distill the oil raw plant material, such as flowers, leaves, wood, bark, roots, seeds, or peel, is put into a distillation apparatus over water. As the water is heated the steam passes through the plant material which then turns the volatile compounds into vapour. The vapours flow within a coil in the apparatus, where they then condense due to the structure of the coil where they then turn back to liquid. This liquid is the essential oil which is then collected and bottled.Most oils are distilled in a single process, however one exception is ylang-ylang (Cananga odorata), which takes up to 22 hours to complete through a complex fractional distillation method.Essential oils are generally extracted through this method of distillation, however other processes include expression, solvent extraction, absolute oil extraction, resin tapping, and cold pressing.Unlike most herbal and floral extraction methods which are distilled, citrus peel oils are expressed with cold-pressing which is similar to the method through which olive oil is extracted.
Essential Oil Storage
As mentioned, essential oils are a volatile oil which means their liquid is released into the air which is what makes us able to smell them! Therefore it is important to replace cap tightly after each use. Most essential oils have a shelf life of approximately two years but they likely won’t last you that long if you’re using them correctly :)
What exactly is a volatile aromatic compound? In short, these compounds are small organic molecules that tend to change quickly from their solid or liquid state to a gas at room temperature. The physical and chemical properties of the volatile aromatic compounds that compose essential oils allow them to quickly move through the air and directly interact with the olfactory sensors in the nose.
When essential oils (or any scent) are inhaled through the nose aromatic molecules are carried through the lining of the nasal cavity via small olfactory nerves where millions of sensory neurons lie in a strip of tissue called the olfactory epithelium. The tips of these cells contain proteins called receptors that bind odor molecules. The receptors are like locks and the keys to open these locks are the odor molecules that float past.
People have about 450 different types of olfactory receptors (for comparison, dogs have about two times as many). Once an odour molecule binds to a receptor, it initiates an electrical signal that travels from the sensory neurons to the olfactory bulb (a structure at the base of the forebrain that relays the signal to other brain areas for additional processing). This signal goes to an area on the piriform cortex, a collection of neurons located just behind the olfactory bulb that works to identify the smell. Smell information also goes to the thalamus, a structure that serves as a relay station for all of the sensory information coming into the brain. The thalamus is the "switchboard" of the brain and quickly sends the impulse to specific regions of the brain depending on the type of scent molecule.
The quick signals from the thalamus to different parts of the brain are what conjure up emotions and even specific memories, like when a whiff of cologne at a department store reminds you of an former boyfriend. This happens because the thalamus sends smell information to the hippocampus and amygdala, key brain regions involved in learning and memory. The effects of some scents such as citrus scent molecules can also travel to the pre-frontal cortex of the brain and affect wakefulness and decisiveness. The effects that certain scent molecules have on the receptors which they are places explain why we feel more energized after smelling coffee and citrus or more calm after smelling lavender. This occurs before the reasoning part of the brain can be cued and quick response to scent can explain why scent often affects our mood or sparks a memory without us being aware of why.
In general the type of volatile aromatic compounds present in an essential oil determines both the oil’s aroma and the benefits it offers.