where r is a reaction rate, k is a reaction rate constant (which k = k0
[ROH]3) and [TG] is a concentration of triglyceride (or oil) and t is a
time. In order to calculate the apparent first order rate constants,
the values of the methyl ester conversion at different reaction times
were fitted in Eq. (5).
On the other hand, the transesterification
reactions were carried out at different reaction temperatures and
the respective rate constants were fitted in the Arrhenius equation
(Eq. (6)) in order to calculate the activation energy (Ea) (kJ mol1).