Optimization of Processing Variables for Pistachio Paste Production

Abstract

<em>Background: </em>Pistachios is one of the popular tree nuts in Iran and other countries. The effect of pistachio kernel roasting<br />and milling parameters on the quality of pistachio paste was investigated in this study.<br /><em>Material and Methods: </em>Roasting variables were roasting temperature (90-190°C) and roasting time (5-65 min). Four<br />grinding gap sizes (20, 40, 60, and 80 µm) were used to prepare pistachio pastes.<br /><em>Results: </em>Increasing roasting time and temperature had inverse associations with colour attributes of both kernels and<br />pistachio powders, except for 'a' value of pistachio powder. The hardness (N) and colour parameters (yellowness index, L<br />value and b value) of pistachio kernels and the 'a' value of pistachio powder can be used to control the roasting quality of<br />pistachio kernels. The colloidal stability (CS) of pistachio pastes was found to be affected by particle size.<br /><em>Conclusion: </em>The recommended roasting condition ranges of the kernels for the pistachio paste production were 130-140°C<br />(30-40 min). The most stable pistachio paste was obtained when the gap size of the mill was 20 µm.