Bidimensional modeling applied to oil extraction kinetics of microwave-pretreated canola seeds

The effect of microwaves on canola oil extraction kinetics and on tocopherol and canolol content in oil was studied. Oil was extracted with hexane at constant temperature (298-333 K) at different times (300-64800 s). In general, for each temperature and time, a significant yield increase was achieved by effect of the pretreatment. A modified Fick's diffusion model was proposed to explain the extraction process; the parameters were adjusted to obtain washing fractions and the effective diffusion coefficient, which presented an Arrhenius-type temperature-dependence. The analysis of the parameters allowed to develop a modified bidimensional diffusion model (temperature and time-dependent), appropriately correlating the data for pretreated and untreated samples. An increase in the pre-exponential parameter due to pretreatment was observed, evidencing the influence of microwave radiation on the sample structure. The pretreatment did not significantly affect the oil quality indices, but increased the content of canolol and β and δ-tocopherol isomers.