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SUMMARY:In this study, the effects of different extraction parameters including ultrasound time, temperature and malaxation time on olive oil quality were investigated. The extraction variables ultrasound initial temperature (20-50 °C), ultrasound time (2-10 min) and malaxation time (30-50 min) were studied to obtain ideal conditions of ultrasonic treatment on the olive paste for obtaining of a greater yield in the extraction of oil, while maintaining a maximum level of commercial quality. To evaluate the level of commercial quality, absorbance in the UV region, peroxide (PV) and free acidity values (AV), the total chlorophyll, carotenoid, phenol contents, total antioxidant activity and sensory analysis of EVOOs extracted from Edremit cultivar were determined. The optimum conditions were found to be 50 °C, 2 min and 43.23 min for ultrasound initial temperature, sonication time and malaxation time, respectively. This optimal condition gave an extraction yield of 8.25 % and the acidity value of 0.24 mg oleic acid/100 g olive oil. The experimental values obtained under optimal conditions were in agreement with the theoretical values KEYWORDS: Extraction; Olive oil; Optimization; Quality; Ultrasound; Yield RESUMEN: Efecto del ultrasonido en la extracción de aceite de oliva y optimización de la extracción asistida por ultrasonido del aceite de oliva virgen extra mediante metodología de superficie de respuesta (RSM). En este estudio se investigó el efecto de diferentes parámetros de extracción, incluyendo tiempo de ultrasonido, temperatura y tiempo de malaxación en la calidad del aceite de oliva. Se estudiaron las variables de la extracción como temperatura inicial de ultrasonido (20-50 °C), tiempo de ultrasonido (2-10 min) y tiempo de malaxación (30-50 min) para obtener las condiciones ideales del tratamiento ultrasónico en la pasta de oliva para obtener un mayor rendimiento en la extracción de aceite y manteniendo un máximo de calidad comercial. Para determinar el nivel de calidad comercial, se determinaron la absorbancia en la región UV, índice de peróxido (PV) y los valores de acidez libre (AV), contenido total de clorofila, carotenoides, fenoles, actividad antioxidante total y análisis sensorial de aceites de oliva extraídos del cultivar Edremit. Las condiciones óptimas fueron de 50 °C, 2 min y 43,23 min para temperatura inicial del ultrasonido, tiempo de sonicación y tiempo de malaxación, respectivamente. Estas condiciones óptimas dieron un rendimiento de extracción del 8,25% y un valor de acidez de 0,24 mg de ácido oleico/100 g de aceite de oliva. Los valores experimentales obtenidos en condiciones óptimas estuvieron de acuerdo con los valores teóricos.

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In this study, the effects of leaf addition, maturity stage and storage on the antioxidant content and activity of olive oils (cv. Memecik) were investigated in the 2008/09 and 2009/10 crop seasons. Olive fruits were harvested at two different maturity stages (early and late), and the leaves of the same cultivar were added at different rates (0, 1, and 3 %) prior to oil extraction. After extraction, the oil samples were stored for 18 months and total chlorophyll, α‐tocopherol, total phenolic content and the antioxidant activity [DPPH· (2,2‐diphenyl‐1‐picrylhydrazyl) and ABTS·+ (2,2‐azino‐bis(3‐ethylbenzothiazoline)‐6‐sulfonic acid) radical scavenging] were determined at 6 month‐intervals. Olive leaf addition induced a significant increase in total chlorophyll, α‐tocopherol, total phenolic content, and antioxidant activities in both years (P < 0.001). During the storage period antioxidant content and antioxidant activities in the oils significantly decreased in both years (P < 0.001). However, the oils to which leaf material was added had higher antioxidant contents and activities than those without leaf material addition at the end of the 18‐month storage period. After storage, the antioxidant content and DPPH· radical scavenging activity of control (0 %) samples were lower than those in the leaf added samples (3 %). The data obtained from this study suggested that the addition of olive leaf to oils allowed more functional olive oils with higher antioxidant contents.

Virgin olive oils (VOOs) obtained from olives grown in different regions of Turkey under changing climatic conditions sometimes show different sensory and chemical properties. This study was planned to determine whether these deviations are due to climatic changes or not. For this purpose, five different olive varieties (Ayvalık, Memecik, Gemlik, Nizip Yağlık, Kilis Yağlık) of commercial importance were harvested from the provinces/districts (four different region) where cultivation is intense during the 2017/2018–2020/2021 harvest years. Every year, olive samples were collected from 3 orchards from 13 provinces/districts. One hundred and fifty‐six samples were subjected to the purity, quality and sensory analysis. Basic climatic values (average, minimum and maximum temperature, humidity and precipitation) were examined for four consecutive years. All of the examined olive oil samples were determined within the legal limits in terms of fatty acid composition and fatty acid ethyl ester values. However, delta‐7‐stigmastenol value from the sterol composition was found to be above 0.5% in some samples in all the years studied (total 21 samples). Delta‐7‐stigmastenol values of olive oil samples varied between 0.16% and 1.14%. Multiple linear regression analysis was applied using a genetic algorithm‐based inverse least squares method to determine whether there is a relationship between climate data and delta‐7‐stigmastenol values. According to this result, it has been determined that the delta‐7‐stigmastenol value is high when the annual average relative humidity is low and the annual average temperature is high. There is an urgent need to make forward‐looking plans due to climate change.

This work aimed to investigate the combined effect of harvest time and crop altitude on the fruit and oil quality of two autochthonous Algerian olive cultivars, Chemlal and Azeradj. Fruit morphological characteristics, oil quality parameters, fatty acids and triacylglycerols composition, pigments, tocopherols and oxidative stability were determined. Olives were harvested at four different ripening stages in orchards located at 110, 320 and 490 m altitude, in the olive‐growing region of Kabylia, northern Algeria. Results showed a good discrimination between varieties, which were characterized by specific triacylglycerols and fatty acids profile. Different chemometric analyses carried out on the oil data highlighted the strong influence of variety in relation to the factors studied. Moreover, Principal Component Analysis performed on both fatty acids and triacylglycerols profile allowed correlating the distinct composition with the different varietal sensitivities to changes in crop attitude and ripening stage. Tocopherols showed a remarkable decrease with the ripening progress. Oxidative stability was positively correlated with variations in tocopherols and monounsaturated fatty acids during maturation and altitude changes.

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In this study, six different irrigation treatments were applied to an olive orchard using the drip irrigation method. Five of these were arranged according to 25% (S0.25), 50% (S0.50), 75% (S0.75), 100% (S1.00) and 125% (S1.25) of the evaporation in 5 days of a class ‘A’ evaporation pan, and one control (SC) was arranged so as to bring the reducing moisture at a soil depth of 0–90 cm to field capacity. Yield values were not affected by the irrigation treatment (p > 0.05). In contrast, 100‐fruit weight, pulp ratio, hardness moisture, oil, reducing sugar content and bitterness were affected by irrigation (p < 0.05). Generally, an increase in the amount of irrigation water given in the study was accompanied by a fall in ripeness index values, a rise in moisture content, and a reduction in the oil content of fruit. The highest content of reducing sugar was obtained from S0.25, generally being lower with increase in the water applied. The findings show that application of 25% of the evaporation of a class ‘A’ evaporation pan (treatment S0.25) can be recommended for cv. Memecik. Application of this recommendation can achieve a 72% saving in water and make a significant contribution to the conservation of limited water resources. Copyright © 2017 John Wiley & Sons, Ltd.