Changes in volatile compounds and oil quality with the method of olive tree propagation and saline water irrigation

The main goal of this study was to investigate the effects of moderate saline water irrigation on the composition and quality of olive oil of the “Chemlali” olive cultivar in comparison to a control plot grown under rain-fed conditions from two methods of olive tree propagation (suckers and cuttings). The antioxidant compounds, oxidative stability and volatile compounds of virgin olive oil samples were determined and reported. The irrigation did not affect free acidity and peroxide value and specific ultraviolet absorbance (K232, K270). Whereas, fatty acid composition, oxidative stability, total phenol, total chlorophyll and carotenoid contents were affected by irrigation. Rain-fed virgin olive oils showed a statistically significant higher content of oleic and linoleic acids. However, olive oil samples obtained from fruit of irrigated trees from suckers had a higher content of (E)-2 hexenal (67.2%) and a higher content of total phenols (860 mg kg–1). Interestingly, more stable oil was obtained from moderate saline water irrigated trees from suckers compared to olives from cuttings

Composición química de aceites de oliva virgen de la variedad Chamlali en relación con el método de propagación del olivo

This paper reports for the first time a discrimination study based on the antioxidant compounds, oxidative stability and volatile compounds of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivar (Chemlali) using two methods of olive tree propagation (suckers and cuttings). There were significant differences between the oils from the two methods. Olive oil samples obtained from the fruits of trees from suckers had a higher content of oleic acid (63.8%), higher contents of chlorophyll and carotenoids (3.01 mg/ kg and 1.9 mg/kg respectively), a higher content of (E)-2 hexenal (66.1%) and a higher content in total phenols (890 mg/kg). Interestingly, more stable oil was obtained from the olives from suckers compared to the olives from cuttings. These results can be used to discriminate and to characterize the Chemlali olive oils from each origin of olive tree.En este trabajo se presenta por primera vez un estudio de discriminación basado en compuestos antioxidantes, estabilidad oxidativa y compuestos volátiles de muestras de aceites de oliva virgen obtenidos de frutos de la principal variedad de aceitunas tunecinas (Chemlali) a partir de dos métodos de propagación del olivo (chupones y estaquillas herbáceas). Se han encontrado diferencias significativas entre los aceites obtenidos por los dos métodos. Las muestras de aceites de oliva obtenidas de frutos de árboles de chupones tenían una mayor proporción de ácido oleico (63,8%), un mayor contenido de clorofila y de carotenoides (3,01 mg/kg y 1,9 mg/kg, respectivamente), un mayor contenido de (E)-2 hexenal (66,1%) y un mayor contenido en fenoles totales (890 mg/kg). Curiosamente, el aceite más estable se ha obtenido de las aceitunas de árboles de chupones, en comparación con las aceitunas de árboles de estaquillas herbáceas. Estos resultados pueden ser utilizados para discriminar y caracterizar los aceites de oliva Chamlali según el origen del olivo

Sterolic composition and triacylglycerols of Oueslati virgin olive oil: comparison among different geographic areas

The main triglycerides (TG) identified in the Oueslati virgin olive oil were 1,2,3-trioleylglycerol (OOO), 2,3- dioleyl-1-palmitoylglycerol (POO) and 2,3-dioleyl-1-linoleylglycerol (LOO) representing more than 80% of the total area of peaks in the chromatogram. Other minor triacylglycerols were 2,3-dioleyl-1-stearoylglycerol (SOO), 2-oleyl-3-palmitoyl-1-stearoylglycerol (SOP), 1-linolenoyl-2-oleyl-3-palmitoylglycerol (LnOP), 1,2-dilinoleyl-3-palmitoylglycerol (LLP), 1, 3-dioleyl-2-linolenoylglycerol (OLnO), 1-linolenoyl-2-linoleyl-3-oleylglycerol (LnLO) and 1,2,3-trilinoleylglycerol (LLL). The sterol profile of Tunisian virgin olive oils produced from Oueslati cultivar was established by gas chromatography using a flame ionisation detector (GC-MS). More than 10 compounds were identified and characterised. As expected for virgin olive oil, the main sterols found in all Oueslati olive oils were b-sitosterol, D5-avenasterol, campesterol and stigmasterol. Cholesterol, 24-methylenecholesterol, clerosterol, campestanol, sitostanol, D7-stigmastenol, D5, 24-stigmastadienol and D7-avenasterol were also found in all samples, but in lower amounts. Most of these compounds are significantly affected by the geographical origin of the oil. Besides the sterol components, two triterpene dialcohols, erythrodiol and uvaol, were also detected

The phenolic compounds and compositional quality of Chetoui virgin olive oil: effect of altitude

The differences in the chemical composition of virgin olive oils (VOO) obtained from trees of the Chetoui variety cultivated at different altitudes in Tunisia were evaluated. All samples were harvested using the same controlled procedures and were submitted to a controlled processing in the same laboratory mill. Several analytical parameters such as fatty acid composition, amounts of phenols; o-diphenols and pigments were analyzed. All these parameters showed an important effect on the fatty acids and phenols content of the oils. The total phenol content was positively correlated with the altitude, ranging from 817.33 mg/kg (403 m) to 131.91 mg/kg (10 m). However, the results of the regulated parameters in the potential quality classified all the analyzed oils into the ‘‘extra virgin’’ category