Methyl glucose sesquistearate is a mixture of mono- and diesters of a methyl glucoside and stearic acid. Methyl glucoside is a monosaccharide derived from glucose. Stearic acid is a saturated fatty acid that can be obtained from both animal and vegetable fats and oils. In cosmetics and personal care products, methyl glucose sesquistearate functions as an emollient and emulsifier.
As an emollient, methyl glucose sesquistearate works to soften and smooth the skin by lubricating the skin’s surface. It forms a film that helps to prevent evaporation of the skin’s natural moisture. Over time, this increases skin hydration by causing buildup of water in the stratum corneum (the uppermost layer of skin). Methyl glucose sesquistearate can also be used as an emulsifier in products that contain both water and oil components. Mixing water and oil together creates a dispersion of oil droplets in water (and vice versa). These two phases can separate if the product is left to settle. To address this problem, an emulsifier can be added to help the droplets remain dispersed. With an HLB of 6.6, methyl glucose sesquistearate is soluble in oil and gives rise to water-in-oil emulsions.