An overview on eco-friendly polyglycerol esters of fatty acid, synthesis and applications

Polyglycerol esters (PEGs) which are non-ionic surfactants acting as emulsifiers, wetting agents and viscosity modifying agents are used in the cosmetic, pharmaceutical and food industries. They have been proposed as an alternative to ethoxylated glycol-based non-ionic surfactants due to safety issues. PGEs are composed of fatty acid, which is a lipophilic moiety, and polyglycerol, which is a hydrophilic moiety. They are synthesized by several methods, such as direct esterification of fatty acids and polyglycerols, chemical transesterification of fatty acid methyl esters and polyglycerol, enzymatic transesterification using Lipozyme 435, using glycerol carbonate as raw material, using microwave irradiation, etc. PGEs (Polyglycerol esters) are claimed to be green alternatives to the existing emulsifiers used in the chemical industry as the raw material used for synthesis is obtained from vegetable oils which are renewable, and therefore, eco-friendly surfactants for use in a broad number of applications including food, cosmetics, textiles and personal care. The major challenges in the synthesis of polyglycerol fatty acid esters are to increase yield and control the esterification level while minimising side reactions.