Biodiesel is produced from any fat or oil such as Jatropha oil, through a refinery process called transesterification.
Transesterification separates glycerin from raw vegetable oil (or animal fat). The products of this process are biodiesel (or methyl ester) and glycerin, a common ingredient in soap and pharmaceutical products which is a by-product of biodiesel production.
Fuel-grade biodiesel must be produced to strict industry specifications (ASTM D6751 in the USA, EN 41214 in Europe) in order to ensure proper performance.