Drying temperature and extraction method influence physicochemical and sensory characteristics of pistachio oils

Abstract

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.

Differences in Oils from Nuts Extracted by Means of Two Pressure Systems

“…Determination of the regulated physicochemical quality parameters (free acidity, peroxide value, and ultraviolet [UV] absorption characteristic, K 270 and K 232 ), was carried out following the analytical methods described by Regulation EEC/2568/91 of the Commission of the European Union. [14] Free acidity, given as % of oleic acid (or º), was determined by titration of a solution of oil dissolved in ethanol/ether (1:1) with 0.1 M potassium hydroxide ethanolic solution. Peroxide value, expressed in milliequivalents of active oxygen per kilogram of oil (meq/kg), was determined as follows: a mixture of oil and chloroform-acetic acid was left to react with a solution of potassium iodide in darkness; the free iodine was then titrated with a sodium thiosulfate solution.…”

Pistachio oil: A review on its chemical composition, extraction systems, and uses

“…Like other nuts oils, pistachio oil is rich in unsaturated fatty acids. The main component is oleic acid (C18:1), ranging from 51.60 to 81.17% according to varieties and origins (Table ) . The dominant polyunsaturated fatty acid is linoleic acid (C18:2), which presents variations according to varieties, but with a clear inverse relationship between oleic and linoleic acids like in many other vegetable oils .…”

Effect of supplementing crop substrate with defatted pistachio meal on Agaricus bisporus and Pleurotus ostreatus production

“…Several systems may be used to extract the oil from the fruits, such as organic solvent extraction, supercritical fluid extraction or pressure; this last process provides higher‐quality oils, at reasonable prices . Pistachio oil is characterized by the low content of saturated fatty acids and the predominance of mono‐ and polyunsaturated ones, highlighting the oleic acid content …”

“…3 Pistachio oil is characterized by the low content of saturated fatty acids and the predominance of mono-and polyunsaturated ones, highlighting the oleic acid content. 3,4 Once the oil from the pistachios has been removed, a defatted meal remained, which is usually employed in animal feed and as a chemical product base component in paint and enamel manufacture. This by-product can also be used in human feed products, for instance as an additive or condiment in the catering industry (sauces, creams, crunchy sweets, cookies, pasta, shortbreads, etc.…”