Glycerol monostearate, commonly known as GMS, is an monoglyceride commonly used as an emulsifier in foods. It is a white, odorless, and sweet-tasting flaky hygroscopic powder.
DEFINITION
Mixture of monoacylglycerols, mainly monostearoylglycerol, together with variable quantities of di- and triacylglycerols. It is obtained by partial glycerolysis of vegetable oils mainly containing triacylglycerols of palmitic (hexadecanoic) or stearic (octadecanoic) acid or by esterification of glycerol with stearic acid. The fatty acids may be of vegetable or animal origin.
Content:
monoacylglycerols: 40.0 per cent to 55.0 per cent;
diacylglycerols: 30.0 per cent to 45.0 per cent;
triacylglycerols: 5.0 per cent to 15.0 per cent.
CHARACTERS
Appearance: Hard, waxy mass or unctuous powder or flakes, white or almost white.
Solubility: Practically insoluble in water, soluble in ethanol (96 per cent) at 60 °C.
IDENTIFICATION
First identificationiC, D.
Second identificationiA, B.
A. Melting point: 54C to 66C.
Introduce the melted substance into the capillary tubes and allow to stand for 24 h in a well-closed container.
B. Thin-layer chromatography: To pass the test.
C. Composition of fatty acids (see Tests) according to the type stated on the label.
D. It complies with the limits of the assay (monoacylglycerol content).
TESTS
Acid value: Maximum 3.0, determined on 1.0 g.
Use a mixture of equal volumes of ethanol (96 per cent) R and phenylmethane R as solvent and heat gently.
Iodine value: Maximum 3.0.
Saponification value: 158 to 177, determined on 2.0 g. Carry out the titration with heating.
Free glycerol: Maximum 6.0 per cent.
Composition of the fatty-acid fraction of the substance:
Glycerol Monostearate Type I: Stearic Acid is 40-60% and sum of contents of palmic and stearic acids is minimum 90%.
Glycerol Monostearate Type II: Stearic Acid is 60-80% and sum of contents of palmic and stearic acids is minimum 90%.
Glycerol Monostearate Type III: Stearic Acid is 80-99% and sum of contents of palmic and stearic acids is minimum 96%.
Nickel: Maximum 1 ppm.
Water: Maximum 1.0 per cent, determined on 1.00 g. Use pyridine R as the solvent and heat gently.
Total ash: Maximum 0.1 per cent.
ASSAY
Size-exclusion chromatography: To pass the test.
LABELLING
The label states the type of glycerol monostearate 40-55.
