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 differences in volatile profile of pistachio oils 'Aegina' cultivar extracted with two different techniques, 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 α-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.

GC-MS, FTIR and Raman spectroscopic analysis of fatty acids of Pistacia vera (Greek variety "Aegina") oils from two consecutive harvest periods and chemometric differentiation of oils quality.

Pistacia vera oil is a rich source of unsaturated fatty acids, whose presence is associated with high quality and nutritional value. According to the literature, fatty acid oil composition is not constant every harvest year, but varies mainly depending on climate conditions. Therefore, the knowledge of oil composition in fatty acids is necessary to assess both its quality and its nutritional value. Twenty-two samples (11 samples from the harvest year 2017 and 11 samples from 2018) of the Greek variety "Aegina" were collected from four different Greek regions, from producers following the same cultivation and post-harvest cares. Extraction oil yields were found to be similar (61.7% w/w, 2017; 60.8% w/w, 2018). A reduction of the saturated fatty acids content was determined in 2018 (mean values 12.2% w/w against 13.8% w/w in 2017) by Gas Chromatography-Mass Spectrometry, accompanied by an increase of the unsaturated ones (mean values 87.9% w/w against 86.2% w/w in 2017). These results indicate that the harvest year 2018 may be considered superior to 2017 in terms of quality and nutritional value and may be correlated with an increased mean rain rate in 2018 and a slight decrease of the mean temperature. Fourier transform infrared (FTIR) and Raman spectroscopic studies of the oils were also performed. Three chemometric models were developed for the two consecutive harvest years of pistachio oil and the discrimination was based on GC-MS analysis, FTIR and Raman spectroscopic data combined with cross-validation techniques and comparison among them. The most successful chemometric model was that based on FTIR spectroscopy, which has the advantage of speed, simplicity and economy. Such a chemometric model may help in estimating the quality of Pistacia vera oils.

Rapid screening on aflatoxins' presence in Pistachia vera nuts using diffuse reflectance infrared Fourier transform spectroscopy and chemometrics.

Aflatoxin contamination in pistachios has been analyzed in this work, using Diffuse Reflectance Infrared Spectroscopy (DRIFTS) with chemometrics. Forty-nine Greek pistachio samples of different aflatoxin concentrations were classified into aflatoxin and non-aflatoxin groups using the 3035-2821, 1770-1721, 1570-1481 and 1260-1061 cm-1 spectral regions in Kubelka-Munk conversion and first derivative form. A chemometric model was developed using twenty-eight samples as calibration, 11 as validation and 10 as test set. The discrimination analysis separated correctly the 100% of the calibration and the validation set and the 80% of the test set. The proposed chemometric model is simple, rapid, economical and environmentally friendly since it does not require chemical pre-treatment of the samples. It is expected that the present method may be proved useful in food industry and the inspection authorities as a rapid decision-making tool to detect batches that must be rejected and enhance consumers' protection from aflatoxin contaminated pistachios.

Study of the Quality Parameters and the Antioxidant Capacity for the FTIR-Chemometric Differentiation of Pistacia Vera Oils.

The aim of this work was to characterize the pistachio oil of the Greek variety, "Aegina", evaluate its various quality indices, and investigate the potential use of FTIR as a tool to discriminate different oil qualities. For this purpose, the antioxidant capacity, the tocopherol content and the oxidation and degradation of fatty acids, as described by k, Δk, R-values, and free acidity were evaluated using 45 samples from eight different areas of production and two subsequent years of harvesting. The antioxidant capacity was estimated using 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS) and 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazine (DPPH) assays, and the tocopherol content was quantified through HPLC analysis. FTIR spectra were recorded for all samples and multivariate analysis was applied. The results showed significant differences between the oil samples of different harvesting years, which were successfully discriminated by a representative FTIR spectral region based on R-value, total antioxidant capacity, and scavenging capacity, through ABTS. A similar approach could not be confirmed for the other quality parameters, such as the free acidity and the tocopherol content. This research highlighted the possibility of developing a simple, rapid, economic, and environment friendly method for the discrimination of pistachio oils according to their quality profile, through FTIR spectroscopy and multivariate analysis.