Experimental design plays an important role in several areas of science and industry. Experimentation is an application of treatments applied to experimental units and is then part of a scientific method based on the measurement of one or more responses. It is necessary to observe the process and the operation of the system well. For this reason, in order to obtain a final result, an experimenter must plan and design experiments and analyzes the results. One of the most commonly used experimental designs for optimization is the response surface methodology (RSM). Because it allows evaluating the effects of multiple factors and their interactions on one or more response variables it is a useful method. In this section, recent studies have been compiled which aim to extraction of plant material in high yield and quality and determine optimum conditions for this extraction process.

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 effect of ultrasound (US) combined microwave (MW) drying of green olive slices was studied. Olive samples were exposed to ultrasound (5 and 10 minutes; 32 KHz) at room temperature before dried at microwave at 3 different power level (180W, 450 W and 800 W). The drying and rehydration characteristics and quality parameters of olives were determined by comparing with obtained by non-ultrasound pretreated MW dried samples. Midilli et al.and Diffusion models were the most suitable models for US-MW drying with the highest R 2 , and lowest RMSE and chi square values. Total phenolic compounds (TPC) of olive slices reduced during drying in all treatments, however TPC of ultrasound pretreated samples were relatively higher those non treated samples dried at same microwave. Increasing of microwave level and ultrasound time decreased the total drying time up to %42.5. This study showed that US-MW can be a useful combine drying method for olive slices which decreased the drying time and improved the qualitative properties of olives.

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