Modelling of virgin olive oil extraction using response surface methodology

Malaxation of the paste is the most important step for virgin olive oil extraction because it affects both oil yield and quality. In this work the influence of temperature and mixing time on oil yield, quality parameters and oil composition in photosynthetic pigments and total polyphenols is assessed by using Response Surface Methodology. Seven Picual-variety olive samples from two consecutive seasons, with different maturity index, were used. Results show that temperature and malaxation time exert a positive influence in olive yield, with optimal values ranging from 20.1 to 32.2 degrees C and from 73.3 to 90 min. Oil quality decreased slightly as temperature and time of malaxation were increased. Top quality oils were obtained below 30 degrees C and shorter mixing time. The oil content in photosynthetic pigments increased with temperature and mixing time, while total polyphenols increased with temperature but decreased with mixing time.