– a natural and fascinating substance which is used in the pharmaceutical, food and cosmetic industries, amongst others.
Glycerine is an extremely versatile substance which merits a light physical and chemical explanation and a discussion of its many everyday application functions.
WHAT IS GLYCERINE?
In short, glycerine is a transparent, odourless, viscous/thick liquid with a relatively sweet taste, which is well-known to many folk, for myriad purposes. Although it tastes sweet, it does not raise blood sugar levels, as it is metabolised differently to table sugar (sucrose), hence it is often used in ‘low carb’ foods. Because it is also an effective humectant it keeps such food products moist, as well as sweet – with the added bonus of not contributing to bacterial tooth decay. Humectants are substances that draw water from the atmosphere to, for example, the skin, making it feel more moisturised.
Glycerine is thicker than water, which slows down movement, making liquid glycerine syrup-like, and resistant to freezing.
WHAT’S IN A NAME?
Glycerine, like many other chemical compounds, is known by a variety of names – either way, it’s the same thing though. For example, it is sometimes spelled without the ‘e’, or called glycerol. Chemically, however, it is listed by the International Union for Pure and Applied Chemistry (IUPAC) as propane-1,2,3-triol. Although it’s known by several names, from its IUPAC name one can deduce that it is an organic alcohol (a polyol), with multiple hydroxyl groups. The benefit of IUPAC naming is similar to the importance of using proper botanical (scientific) naming when referring to plants: i.e. you know exactly what you’re getting, which isn’t always the case when using common or folk names for substances.
WHERE DOES IT COME FROM?
Glycerine is one of the basic components for all fats and oils. It is derived from the hydrolysis (a chemical reaction where something reacts with water and is changed into another substance) of fats and fermentation of sugars and is usually derived from coconut or palm oils. It can however also be extracted from several sources: vegetal/vegetable fats, animal fats or petroleum/natural gas (the latter is known as synthetic glycerine) – so if you don’t want to use petroleum-derived substances, check the origins of the glycerine before you buy.
There are different grades of glycerine or glycerol: e.g. food-grade vegetal glycerine consists of 99.7% pure glycerine and 0.3% water. Besides its use in the food industry, it is also used in the textile, cosmetic, toiletry, household, pharmaceutical (as a medicine delivery system), and the explosives industries.
So, while basically safe and helpful on the one hand, on the other hand, glycerol is also used to produce nitroglycerin (dynamite). In general though, glycerine is a very safe and versatile substance, since it is soluble in both water and alcohol. For example, in medicine manufacture (especially herbal medicines) vegetal glycerine can be used as a substitute for alcohol in the making of botanical extracts. On the up-side, one ends up with an alcohol- free substance, but on the down-side the products have a much shorter shelf-life than alcohol extracted substances.
Some other medicinal uses for glycerine include its addition to topical remedies for skin problems like rashes, psoriasis, eczema, burns, wounds, bedsores, chilblains, gum disease and inflammations of the mouth, plus making up part of formulations for glycerine suppositories, which are effective laxatives. In bygone days a solution of glycerine of borax for oral hygiene and inflamed and ulcerated conditions of the mouth and throat used to be standard treatment in hospitals. It was also routinely used for treating oral thrush in babies’ mouths, as well as sore nipples in breast- feeding mums, and is still in successful folk use today for these purposes.
If you read labels you’ll no doubt see glycerine listed in a wide range of products, including toothpaste, shampoo, skin lotions, and transparent and natural (hand-crafted) opaque soap. Because it’s such a saleable commodity, the glycerine produced in commercial soap making (as a by-product) is usually extracted and sold separately – hence commercial soaps (actually syndet bars – SYNthetic DETergent) do not contain the benefits and qualities of handmade soap in which all the glycerine molecules remain such as cleaning and moisturising. As an avid soap and natural toiletries-maker, and DIY cosmetics teacher, I love it as an ingredient, or as an integral part of real artisanal soap.
PROPYLENE GLYCOL GLYCEROL/ GLYCERINE CONUNDRUM
Glycerol can also be produced from propylene. Propylene glycol (PG) is an organic compound that is derived from natural gas, and which is often used as a substitute for glycerine.
Few chemical substances are as versatile, or have as many applications, as glycerine – a crystal-clear gem in my book. It’s considered an earth-friendly, ‘green’ ingredient that is safe to use, over a wide spectrum of applications, is freely available, and inexpensive into the bargain.