Understanding the Terms: Glucoside, Glycoside, Glucose, Glycerol and Glycerin

Glycosides are a class of complex chemicalcarbohydrates and glycogen. Fermentation of glucose
compounds in plants. They are broken down by plantby yeast produces ethyl alcohol and carbon dioxide.
enzymes into sugars, among which glucose isGlucose is made industrially by the hydrolysis of starch
generally included, and into other substances. The termunder the influence of dilute acid or, more commonly,
glucoside is often used synonymously with glycoside,under that of enzymes. It is chiefly used as a
but in its more specific meaning it refers to glycosidessweetening agent in the food-processing industries. It is
that yield glucose. Each glycoside in a plant isalso used in tanning, in dye baths, in making tableted
hydrolyzed by an enzyme, usually a specific enzymeproducts, and in medicine for treating dehydration and
found in the same plant. The enzyme emulsin,for intravenous feeding.
however, causes hydrolysis of several glycosides. TheGlycerol or Glycerin, C3H8O3, is a colorless, odorless,
enzymes and glycosides are stored in separate plantsweet-tasting alcohol, with a specific gravity of 1.26. It
cells until the reaction products of the glycosides areboils at 290° C (554° F) and melts at 18° C
needed and the enzymes are activated.(64.4° F). Liquid glycerol resists freezing but may
Glycosides are believed to serve several purposes incrystallize at low temperatures. It forms a solution with
the plant. Glycosides are bitter tasting, and it is believedwater in any proportion, and dissolves in alcohol in all
that they help keep birds and insects from eatingproportions, but is insoluble in ether and many other
seeds and fruit before they are fully grown, by whichorganic solvents. The term glycerol refers specifically
time the glycosides have been converted to sweetto the compound, the formula of which is given above,
sugars. When a plant tissue is bruised, the enzymeswhereas glycerin may also refer to glycerite (glycerol
hydrolyze the glycosides into products, such as phenolin solution) or other solutions of or preparations made
compounds and acids that have an antiseptic actionfrom glycerol.
and prevent decay of the damaged tissues.Simple fats and oils are esters of fatty acids and
Glycosides are soluble in water and are obtained fromglycerol crude glycerol is purified by distillation after
plants by water extraction. They are mostly colorlessobtaining it as a by-product after fats and oils have
crystalline solids with a bitter taste. Simple glycosidesbeen treated with alkali to form the soap. Of the
have been synthesized in the laboratory, and severalannual glycerol production about 40 percent comes
hundred glycosides have been extracted from plantsfrom soap making. The rest is synthesized from the
and used for many purposes. Among the importantpetroleum products ally alcohol, C3H6O, or propylene,
glycosides are indican, used for dyeing; digitalin, used inC3H6, or by the catalytic action of hydrogen on sugar
medicine; and the saponins, foaming agents usedat high temperature and pressure.
industrially and medicinally.The most common use for glycerol is in the making of
Glucose, a monosaccharide sugar, C6H12O6, is foundalkyd resins. Other important applications are in the
in honey and the juices of many fruits; the alternatepreparation of drugs and toilet articles, including
name grape sugar is derived from the presence oftoothpastes; as a plasticizer in cellophane; and as a
glucose in grapes. It is the sugar most often producedmoistening agent in tobacco products. Because
by hydrolysis of natural glycosides. Glucose is a normalcheaper products are now available, only 5 percent of
constituent of the blood of animals. Glucose is a whitethe production of industrial glycerol goes into the
crystalline solid, less sweet than ordinary table sugar.making of nitroglycerol explosives. Because of its
Solutions of glucose rotate the plane of polarization ofaffinity for water and its high viscosity, glycerol is a
polarized light to the right; hence the alternative namevaluable constituent in stamp pad inks. Pumps for
dextrose (Latin dexter, “right”). Glucosepetroleum products are lubricated by glycerin because
crystallizes in three different forms. The degree ofit resists dissolving in petroleum liquids. Because of its
rotation of polarized light is different for each form.high viscosity and its nonpoisonous character, glycerin
Glucose is formed by the hydrolysis of manyis a suitable lubricant for food-processing machinery.