As well as for turbidity response, the increase in pH values (X1)
and in chitosan concentration (X2) decreases the juice color (Y3),
while the slow agitation time (X4) has a slight positive effect on the
color response. Jiang et al. [12] observed higher color removal at
pH 7 than at pH 4 related to electrostatic interactions. The results
obtained in this study (Table 3) showed that the effect of chitosan
concentration was more expressive at lower pH values, since in
an acidic solution charge neutralization can be achieved just with
higher chitosan contents [12].