The FAME content in biodiesel is an important parameter as it can have a significant influence on the quality and the performance of the fuel. FAME blended biodiesel have the tendencies to react and to form acidic by-products which can reduce the lifetime of the engine.
FAME blended fuels are also not allowed in many applications, i.e. jet fuels and it is often a legal requirement to be able to identify the FAME content of fuel for quality control purposes.