Thermal treatment is essential when using zinc for retaining
green pigments, as heat is needed to dislodge Mg2+ and improve
the diffusion of Zn2+ into pear peel tissues so that zinc complexes
can be formed. This explained why pear presoaked in zinc solution
at room temperature was not as green as that blanched (heated) in
zinc solutions (sample number “2” versus “3” in Figure 2).