Figure 3.

Coefficient bar plot and response surface related to the DOE empirical model. The bar plot shows the magnitude and the correlation (positive or negative) of the coefficients with respect to the response (scores on PC1). The brackets represent the confidence intervals at p = 0.05, and the stars indicate the significance of the coefficients (* = p < 0.05, ** = p < 0.01, *** = p < 0.001). The response surface graphically depicts the predicted response trend as time and temperature change, keeping the quantity fixed at the maximum level.