What is Glycerin?
Glycerin (or glycerol) is a clear, odorless liquid with a thick consistency and sweet taste. It is a common ingredient in many food and pharmaceutical products for moisture, thickness and sweetness (unlike sugar, it does not cause dental cavities).
The name glycerol is derived from the Greek word for sweet – glykys, and the names glycerin, glycerine, and glycerol are used interchangeably.
How is Glycerin made?
Vegetable oils and animal fats both have the same chemical makeup with triglycerides as the main component. The name describes the make-up: the backbone glycerin, which has three (tri) chains of fatty acids that are attached to the glycerin. To isolate the glycerin, it must be split from the fatty acids. This can be done by using one of two methods: hydrolysis or transesterification.
Hydrolysis separates the fatty acid from the glycerin by heating oil or fat to a high temperature under a vacuum. The fatty acids float to the top of the tank and the glycerin water (“sweet water”) sinks to the bottom. The impurities are removed from the glycerin water, the water is evaporated off, and the glycerin is then distilled and purified.
In recent years, glycerin has begun to be produced from another source – biodiesel production. Biodiesel is a renewable, clean-burning diesel replacement made from vegetable oil, waste cooking oil or animal fat, which is reducing dependence on petroleum and improving the environment. It is produced in many counties and all over the USA (currently there are 200 biodiesel plants across the USA). Glycerin from biodiesel production is produced by transesterification, which separates the fatty acid from the glycerin by reacting the oil or fat with methanol and a catalyst (a chemical used to speeds up chemical reaction). The fatty acids become biodiesel and the glycerin is distilled and purified. Biodiesel is only economically viable when oil/fat prices are low and/or when there is government subsidy.
Glycerin can also be made synthetically by processing propane (a byproduct of petroleum processing). Propane can be treated with chemicals in a multi-step process to make synthetic glycerin. The glycerin is then distilled and purified and is mainly used in pharmaceuticals.
Is glycerin kosher?
Glycerin is kosher if it is made from kosher vegetable oil or petroleum and processed on kosher equipment. A lot of glycerin is made from animal fat, processed on the same equipment as animal glycerin or made from used oil from non-kosher establishments, rendering the glycerin non-kosher. Glycerin is not “pogum” and usually it is not “botul b’shishim”. Glycerin or any product containing glycerin can only be used with acceptable kosher certification.