There are several methods in which Vegetable Oils are extracted. These different Extraction Methods can affect the quality, aroma, and appearance of oils, making it important to know the difference between them.
When an oil is extracted by expeller pressing, the raw plant material is mechanically crushed and pressed to produce oil. There can be a great deal of heat produced during this process, which can diminish certain beneficial components of fragile oils. Expeller Pressed Oils often have less natural aroma, and are clearer and more stable.
Like conventional expeller pressing, cold pressed extraction involves physically pressing plant materials. However, the temperatures involved in cold pressed extraction are carefully controlled, helping to preserve the fragile components contained in vegetable oils. Cold Pressed Oils can sometimes have a stronger natural aroma than conventionally expeller pressed oils. They can also contain a larger proportion of natural esters, creating a cloudier, more viscous oil.
Certain Oils are often extracted using a solvent. A chemical solvent is added to plant material in order to extract the oil, after which, the solvent is removed. This process can be very cost effective, but is not favored by purists or aromatherapists as a trace amount of solvent is often left in the finished product.
This exciting new process of extraction provides a way to extract extremely pure oil from even the most fragile of plants and botanicals. CO2 gas is used to press oil from plant material in a sealed chamber. After the oil has been extracted, the CO2 gas is vented, leaving a completely pure oil or extract. Certain CO2 Oils or Extracts are combined with additional ingredients in order to ensure stability. Check the INCI names of the CO2 Oils and Extracts to see exactly what each one contains.
Infusion or Maceration
During maceration or infusion herbs, plants, or botanicals are incorporated into base oils, often Sesame or Coconut Oil. While there are any methods of maceration and infusion, the most common methods involve heat or time. Ayurvedic Oils sometimes incorporate a special infusion method that involves brewing an herbal infusion in water, adding it to a base oil, then carefully evaporating the water from the oil, leaving the extract in the base oil.
Many Oils are refined after pressing to remove natural esters or plant materials that can cause cloudiness, increased viscosity, odor, or even instability. While certain users prefer to use oils that have been refined as little as possible, refined oils are ideal for use in formulas where shelf stability, odor, and appearance are priorities. Highly refined oils are often included in commercially made products for these reasons.
Since natural color can sometimes be troublesome to formulators, certain oils are "bleached" to reduce their natural color. Bleaching is often accomplished by filtering with Fuller's Earth Clay.
Many natural oils contain potent aromas. Sesame Oil, for example, can be found in both deodorized and natural varieties. The difference is striking! Because formulators often prefer to add their own aroma to skin care products, deodorizing can be a very important step in oil production. However, deodorization often involves exposing an oil to very high temperatures, which many believe can reduce the beneficial qualities of an oil.
Organic Oils are produced by special methods which prohibit the use of chemicals or high temperatures during production. As a result Organic Oils can very greatly in appearance, texture, and aroma from even cold pressed conventional oils.