Although herbal extracts come in many forms, they have one common feature. Extracts represent naturally occurring phytochemicals (plant produced compounds) that have been removed from the inert structural material of the plant that produced them. The main advantage of using extracts over raw herb is that once extracted from the plant matrix, the phytochemicals by pass the need for digestion and are far more readily absorbable. Liquid extracts also offer greater convenience than consuming an herb in its raw form.
Extracts are typically categorized by the solvent used to make them and/or by their form. Some of the more common solvents that are used include water, alcohol, glycerin, and vinegar. The inherent qualities of each of these solvents will attract different phytochemicals in an herb. Watery extracts made by infusion or decoction are used as teas, rinses and the base for syrups and other products.
Tinctures are liquid extracts made with alcohol and may include other food-grade solvents. Alcohol extracts a wide range of phytochemicals and is an excellent preservative. It may also be diluted with water to adjust alcohol content and glycerin may be added to curb excessive precipitation of the finished extract.
Food-grade glycerin is a low glycemic index sweetener often used as a solvent to make alcohol-free liquid extracts. While most glycerites lack appreciable alcohol, intermediate extraction may be carried out with alcohol on occasion. In this case alcohol is used to form the initial extract, and is then removed from the finished product with glycerin added in its place.
Vinegars are not common, but are experiencing a bit of resurgence in popularity. These are made by extracting herbs directly in vinegar. Apple cider or other plant based vinegars are most desirable in this case.
Oils are fatty oils that have been infused with herbs for topical use and may be called herbal oils or infused oils. The fatty oil used as a base is commonly from olive, sesame or coconut, although many other sources may be used.
Essential oils are the volatile components that have been separated from an aromatic herb. Quality essential oils are either steam distilled or, in the case of herbs like citrus peel, pressed directly from the fresh herb. Essential oils are very strong preparations and are well diluted for internal use.
Powdered extracts are formed by drying liquid extracts including tinctures and water extracts, often under vacuum. Powdered extracts are most commonly used in capsules and tablets. Because the solvent is removed from the final product, some powdered extracts are made with solvents other than ethanol and water. Solvent labeling is not required on powdered extracts, but transparent labeling will include the solvent(s) used. Traces of solvents will remain in the extract, which should be tested.
Supercritical extracts are made by extracting herbs with a gas, usually carbon dioxide, at low temperature and high pressure to bring it into the supercritical state. These are semi-solid extracts representing the fat-soluble components of an herb that are generally seen in softgel form.
