Optimization of pistachio oil extraction regarding processing parameters of screw and hydraulic presses

- Two different pressure systems were compared in relation to physicochemical and sensory properties of pistachio oil.
- Differences in chemical composition caused by processing conditions were discussed.
- Pressure systems produced two different pistachio oils with differentiated physicochemical and sensory characteristics.
- Consumer preferences for oils extracted by hydraulic and screw presses were evaluated.
- Processing conditions affected polyphenols, stability and sterols of pistachio oil.

Optimization of pistachio oil extraction with hydraulic and screw presses regarding yield, physicochemical and sensory analysis of obtained oils was developed. In addition, pistachio defatted flour was also analysed. In the hydraulic press extraction, no differences were found regarding yield and physicochemical characteristics in oils. However, sensory analysis suggested extraction using roasted pistachios (100 °C/30 min). In the screw press differences were found in yield and sensory attributes. Oil extraction with lower rotational speed (17 rpm) resulted in higher yields and the oil was more valued by consumers. Pistachio flour obtained with the two presses presented differences in moisture, fibre, nitrogen, protein and ash content. The lack of influence of extraction parameters in physicochemical characteristics of oil suggested to change the focus to yields and sensory evaluation of oils. Pistachio flour as a by-product had elevated protein content.