The recent EU directive 2009/28/EC, aimed at promotingthe use of energy from renewable sources, paid specialconsideration to the production of biofuels, in particularthose with no impact on the food chain. In the previous UEdirective 2003/30/EC, biodiesel is defined as “a methyl esterproduced from vegetable or animal oil, of diesel quality, to beused as biofuel”.Nowadays most of biodiesel is produced through thetransesterification of the triglycerides contained in ediblevegetable oil with methanol and in presence of an alkalinecatalyst. The competition with the food requirements not onlypose ethical issues to the exploitation of food-grade oils forenergy purposes, but also increase the final cost of biodieselproduction, making it not competitive with normal diesel. Wasteoils or specifically selected vegetable cultures represent potentialsubstitutes to edible oils.The main drawback of this kind of substrates is their high contentof free fatty acids (FFA), which cause saponification problemsduring the transesterification. Moreover, FFA concentrationslower than 0.5 percent per weight are required by the Europeanstandard for biodiesel EN 14214. An efficient standardizationm ...