Where refers to the component (i.e., TAG, DAG, MAG, FFA), is the experimental data number, is the experimental concentration, and is the model calculated concentration of component j .

3. Results and Discussion

It was verified, during preliminary tests, that due to the oil present in the in natura seeds, the particles of this type of seeds were aggregating. Thus, the in natura seeds were used in a bigger granulometry compared to the oil-free seeds.

3.1 CCRD Results for In Natura Seeds

In Table 1 the results of assays for the use of in natura seeds as catalysts are presented, with a observed variation of 3.97 to 84.51% in the yield of the enzymatic hydrolysis. In the Pareto graph (Figure 1 ) the significant variables (95% of significance level) were identified being the catalytic/substrate and buffer/oil mass ratios, with positive linear effects and negative quadratic effects on the yield. The catalyst/substrate ratio is the most significant effect, and the ultrasound power variable was not significant in the evaluated conditions.
The RSM equation is given by Equation (10). The f-test was employed to evaluate the model. The calculated f-value (67.19) was notably higher than the critical f-value (3.68), from the analysis of variance (ANOVA), which validates the model statistically within the studied range. The regression model accuracy can also be observed based on the coefficient of determination (R2) of 0.99, indicating that the enzymatic hydrolysis yield of the Crambe oil can be well described as a function of ultrasound power and catalytic/substrate and buffer/oil mass ratios (Equation 4 ) in the investigated conditions range.