In which, \({FFA(\%)}_{\text{Initial}}\) is the initial acidity of the
Crambe oil.
2.5.1. CCRD
Experiments
The effects of the mass ratio of buffer solution/oil (B/O),
catalyst/substrate (C/S), and ultrasound power (Po) were assessed
through the use of a Central Composite Rotational Design (CCRD) with
central and axial points, the values of the design were determined after
preliminary experiments. Seventeen essays were performed for each
design, with three replicates on the central point, and six experiments
of axial points. The variable levels of the CCRD for in natura seeds
were: ultrasound power of 31.40%, 45.0%, 65.0%, 85.0%; and 98.64%;
B/O mass ratio 0.07, 0.45, 1.00, 1.55, and 1.93; and C/S mass ratio of
0.01, 0.07, 0.16, 0.25, and 0.31. For the oil-free seed particles:
31.40%, 45.0%, 65.0%, 85.0%, and 98.64% for ultrasound power; 1.13,
1.40, 1.80, 2.20, and 2.47 for the B/O mass ratio; and 0.010, 0.020,
0.035, 0.050, and 0.060 for C/S mass ratio. All the experiments were
carried out for three minutes. The response of the experimental design
was the hydrolysis yield, analyzed through the software Statistica
version 7.0 (StatSoft Inc., USA). The validation of the model was
performed with the software Maple version 13.0 (Waterloo Maple Inc.,
Canada).
2.5.2. Kinetic
Experiments
Kinetic experiments were performed at the conditions of higher yield
obtained during the CCRD experiments, where for each reaction time, a
different test was performed. Additional experiments were performed in a
refrigerated incubator with agitation (shaker) at room temperature and
140 rpm.