Thermophysical properties of different olive oils: Evaluating density and rheology through a fluid dynamic approach

Abstract

The aim of this study was to investigate the Newtonian viscosity and density of different types of olive oils with the ultimate aimof optimizingthe unit operationsinvolvedin their productionprocess. Atotal of14oils were selected and tested at a wide range of temperatures. These included ten extra virgin olive oils (EVOOs) and four olive oils (OOs) from five different countries of origin. The oils were analyzed to determine their fatty acid (FA) composition and all were found to contain large amounts of monounsaturated FAs such as oleic acid. FAcompositiondid notappear to influencedensity, but viscosity demonstrated slight differences in activation energy inaccordance withmonounsaturated(MUFA) andpolyunsaturated fatty acid (PUFA) content. Both viscosity and density were affected by temperature. When the oils were heated, viscosity decreasedexponentially followinganArrhenius typeequation, whiledensitydecreasedlinearly. Rheological data was fitted well to theoretical results for absolute temperature and FA composition simultaneously, displaying fitting parameters different to those published in literature. Abrief study of the fluid dynamics of the oils indicated close agreement between theoretical and experimental friction factor, confirming the accuracy of the prediction models reported in this work.