Study of volatile compounds in Greek pistachio (Pistacia vera L. 'Aegina' cultivar) oils using Soxhlet and ultrasound assisted extraction

Headspace solid-phase microextraction followed by gas chromatography-mass spectrometry (HS-SPME/GC-MS) represents the most used solvent-free methodology for the characterization of the complex and heterogeneous mix of volatile compounds. The present study investigates the dif-ferences in volatile profile of pistachio oils 'Aegina' cultivar extracted with two different tech-niques, ultrasound assisted extraction (UAE) and Soxhlet. Differences were observed both in the pistachio oil yield and the composition of the volatile compounds among these two groups of samples, which were significantly influenced due to the different thermal conditions. In terms of pistachio oil yield, the Soxhlet extraction technique was proven more efficient (52.5-68.2% w/w) than the UAE type (28.2-42.6% w/w). A total of 34 and 30 volatile compounds were identified for UAE and Soxhlet, respectively. The main ones associated with UAE were & alpha;-pinene, octane and decane, while the volatiles formed as a consequence of Soxhlet extraction were decane, nonanal and (E)-2-decenal. Terpenes' concentrations were found decreased in Soxhlet's samples, but hydrocarbons and aldehydes were significantly increased in these samples. Numerous studies concluded in common results. However, this article is the first to explore the influence of different extraction types on the volatile profile of the unique flavour and odor pistachio oil 'Aegina' cultivar.

Automated summary

Headspace solid-phase microextraction followed by gas chromatography-mass spectrometry (HS-SPME/GC-MS) is the most commonly used solvent-free method for analyzing the volatile compounds in pistachio oils. This study compared the volatile profiles of pistachio oils extracted using two different techniques (ultrasound-assisted extraction and Soxhlet). Differences in oil yield and composition of volatile compounds were observed between the two groups of samples, which were attributed to the different thermal conditions. This article is the first to explore the influence of different extraction methods on the volatile profile of the unique flavor and odor pistachio oil from the 'Aegina' cultivar.