Conclusions
In this study, the usability of color parameters in the modeling and optimization of pistachio roasting was investigated. The color in shell, kernel and ground-kernel pistachios changed with higher roasting temperature and longer roasting times. These changes were adequately described by quadratic models of RSM and models by GEP. The GEP models were found to be slightly better than RSM models for description of color changes during the pistachio nut roasting. On the other hand, for optimization process desirability functions in RSM analysis were used successfully in this study.