Through the derivation of Equation 4 , using the software
Maple®, the higher yield for the second-order equation was found under
conditions of 70% ultrasound power, 1.79 mass ratio buffer
solution/oil, and 0.25 mass ratio of catalyst/substrate, in the fixed
condition of 3 minutes at initial room temperature, with a yield of
87.98%. In the same conditions, one experiment was carried out yielding
85.0 ± 2.6%, which confirms that within the studied range, the model
can predict the yield satisfactorily.
The response surface plot for the enzymatic hydrolysis yield of the
Crambe oil with in natura seeds is presented in Figure 2 . Each
of the variables can affect the hydrolysis reaction by giving more or
less energy to the system, causing enzymatic denaturation, modifying the
medium viscosity, and altering the availability of sites for lipase
catalysis. The ultrasound power, however, does not have a significant
effect on the response surfaces in the investigated range, unlike the
B/O and C/S variables. Although the amount of buffer solution affects
the yield of the enzymatic hydrolysis reaction, this effect will have
less influence on the reaction yield above 1.0 (Figure 2-a ). A
similar effect is observed in Figure 2-b , where for a ratio of
catalyst/substrate above 0.15, the impact of the variable is less
significant; conversely, an increase in the yield can still be observed
when increasing the ultrasound power. Notably, a high amount of catalyst
(in natura seeds) makes the reaction medium more viscous, demanding more
ultrasound power to emulsify the medium, resulting in the correlation of
the two variables. In Figure 2-c , the effect of the most
significant variables is evaluated simultaneously, and a higher
correlation between both variables can be observed, resulting in
increased yield as both variables increase.