Temperature and Storage Age-Dependence of Olive Oil Viscosity in Different Locations in Palestine

Abstract The dynamic viscosity of olive oil samples of different storage ages in yearly and weekly basis from different locations was measured as a function of temperature. In this study, the overall results of the effect of dynamic viscosity as a function of storage age in yearly and weekly basis indicate a decrease of dynamic viscosity. This study, shows that Abramovic's and Andrade's formulas that describe the dynamic viscosity of olive oil as a function of temperature don't fit our experimental data. Accordingly, our experimental data have been fitted to our proposed two-constant formula. As a result the best coefficient of determination (R2) has been found to be 0.999. The P-value of dynamic viscosity for all olive oil samples is ≤ 0.05. This work, also propose three and multi-constant formulas to obtain more suitable prediction of temperature dependence of dynamic viscosity of olive oil samples from different location in Palestine. The best AAD% (percentage of average absolute deviation) was calculated using our proposed formulas to be 0%. The acidity of olive oil samples of different locations and different storage ages in yearly and weekly basis was measured. In this work, the overall results of the effect of acidity as a function of storage age in yearly basis indicate a deterioration of oil quality. The acidity results for some olive oil samples suggest that the oil can be stored for a period not more than 12 years without deterioration. The overall results of weekly basis of this study indicate that the acidity increased incrementally as a function of storage age. The relationships between the viscosity of olive oil samples with temperature and storage age, and the acidity with storage age, have been found by fitting equations.