Sorbitan tristearate is a triester of stearic acid and hexitol anhydrides derived from sorbitol. Stearic acid is a saturated fatty acid that can be obtained from both animal and vegetable fats and oils. Sorbitol is a sugar alcohol that is primarily made from corn syrup.
Sorbitan tristearate has a structure with one hydrophilic (water-loving) end and one lipophilic (oil-loving) end, which allows it to function as both a surfactant and emulsifier in cosmetics and personal care products. Surfactants attract and suspend oil, dirt, and other impurities on the skin and wash them away. Due to these properties, sorbitan tristearate can be found in many different cleansers and body washes.
Sorbitan tristearate can also be used as an emulsifier in formulations 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 value of 2.1, sorbitan tristearate is soluble in oil and gives rise to water-in-oil emulsions.