With regard to lightness (L*), the three-way ANOVA showed that
pressure, time and Stevia concentration had a significant influence
(pb0.05) on this parameter. Compared to the untreated beverages,
lower L* values were found for samples treated by HPP independently
of the Stevia used in the formulation of the beverages. In addition, the
response surface equation obtained in the present study described
the experimental data adequately (R2=0.921, pb0.05, standard
error=5.324), which also was confirmed by the insignificant lack of
fit (p=0.810). The Eq. (8) was as follows: