Mild roasting of walnuts did not affect the quality of the flours that could be used as a functional ingredient in the food industry. © 2017 Society of Chemical Industry.

Drying is an important operation in pistachio processing to ensure good quality. Study of drying parameters is important since they affect the quality, mainly in color, flavor and nutritional value. Hence, drying parameters could also affect pistachio oils. Pistachios of variety Larnaka were dried at different temperatures (room, 30, 50, and 70°C). Changes in physicochemical quality parameters, stability, and chemical composition of the extracted oils were evaluated. Sensory evaluation was also performed. An increase in the peroxide value was observed when pistachios were dried at 70°C or when screw press was used to extract the oil, remaining low in the rest of oils extracted with the hydraulic press. A similar pattern was observed for K 270 extinction coefficient. In addition, the oils from pistachios dried at higher temperatures (50°C, 70°C) showed an increase in polyphenol content and a decrease in stigmasterol. The oxidative stability was slightly higher when screw press was used. Changes in drying temperature and extraction system had no significant effects on fatty acid composition. Color sensory tests indicated a consumer preference for oils from pistachios dried at 70°C, which produced greenish oils. Pistachio oils with different characteristics are obtained depending on the drying temperature used, both of them acceptable by consumers.Practical applications Pistachios are considered nuts with the most nutritional value and a rich source of natural antioxidants. Drying is an important stage during pistachio processing, as it affects their oil fraction. The extraction system may also influence the characteristics of the final product. The combination of the drying temperature and extraction system may produce oils with different characteristics, which could be an interesting alternative in order to fit any consumer preferences.

Nuts are nutrient dense foods especially appreciated for the fatty acids composition of the oil fraction and other bioactive compounds, like polyphenols or sterols. Almond, pistachio, and walnut oils were extracted by two pressure systems (hydraulic press and screw press) in order to obtain virgin oils. A comparison of the fatty acids was performed for oils from different sources. Although the main components of oils (fatty acids and sterols) did not vary according to the system used, some differences among the three types of nut oils were found. Almond and pistachio oil samples showed a similar fatty acid profile with a substantial amount of monounsaturated fatty acids, 70 and 61%, respectively. However, the majority proportion in walnut oils was the polyunsaturated fatty acids (60%). The highest total sterol content was presented by pistachio oils (4476 mg/kg). Screw press oils showed higher values of the regulated quality parameters (acidity, peroxide value, K 232 , and K 270). In the same way, polyphenols and oxidative stability were slightly higher when the nut oils were extracted with a screw press.

The main objective of this study was to evaluate the effect of different deficit irrigation treatments (control, regulated deficit irrigation [RDI]-1, RDI-2, and RDI-3) on the phenolic profile of the olive paste and oil content. Irrigation treatments with more stress water led to a considerable increase in the phenolic compounds of olive paste, especially in oleuropein (60.24%), hydroxytyrosol (82%), tyrosol (195%), and verbascoside (223%) compared to control. A significant increase in the content of total flavonoids and phenolic acids was also observed for these samples. In virgin olive oils (VOO) elaborated from the most stressed olive trees (RDI-2 and RDI-3), a noticeable increase in phenolic substances with antioxidant properties (oleuropein, hydroxytyrosol, tyrosol, secoiridoid derivatives, and o-vanillin) was observed. Consequently, water stress conditions improved antioxidant activity of VOO.

A new aromatization method for olive oils with saffron aqueous extracts rich in safranal has been developed using liquid-liquid extraction. Four flavoured olive oils were obtained (SO1-SO4). SO1 showed the highest safranal concentration (145.89 mg L), followed by SO2 (79.33 mg L), SO3 (0.30 mg L) and SO4 (0.01 mg L). Although flavouring originated a decrease in the quality parameters and the oxidative stability of the oils, even after 7 months of storage, at room and refrigeration temperatures, the oil parameters evaluated were still comparable to those of extra virgin olive oil. Flavored olive oils with less safranal (SO3, SO4) are preferred by consumers.