In Table 6 it is possible to see the values of free fatty acids in the
raffinate phase stream, expressed in mass% on a solvent-free basis.
It can be observed that in the first three extraction steps (i. e., first
four theoretical extraction stages), 91% of total free acidity was
extracted from the degummed rice bran oil. In relation to nutraceutical
compounds, it is also possible to observe the major extraction
effectiveness in the first three steps, as can be seen in Fig. 10.
These results might be due to the large differences in the concentrations
of these compounds, free fatty acids and nutraceutical
compounds, in the feed and solvent streams.
As observed for MAG, DAG and phosphorus, the losses of neutral
oil and nutraceutical compounds were mainly determined by
their solubilities in the solvent. Rodrigues et al. [23] studied the
optimization of the rice bran oil deacidification process using the
surface analysis method and estimated the losses of neutral oil,
c-oryzanol and tocols to the extract stream to be approximately
3 mass%, 12 mass% and 22 mass%, respectively, in one equilibrium
stage