Glycerol is obtained as a by-product of the manufacturing of Biodiesel fuel by a process know as transesterification. It is also obtained from plant and animal sources where it occurs as triglycerides. Triglycerides are esters of glycerol with long-chain carboxylic acids. The hydrolysis, saponification, or transesterification of these triglycerides produces glycerol as well as the fatty acid derivative:
