Thermal diffusivity estimation of mashed potatoes and olive oil at high pressure

Abstract

The effect of high pressure on thermal diffusivity of mashed potatoes and olive oil was studied at a temperature range about 25–100 °C. The preheated sample filled into a cylindrical Cu cup was loaded by nominal pressures of 400 and 500 MPa in a high-pressure chamber. The thermal diffusivity was estimated from the time–temperature decay during pressure holding time. Temperatures were measured at three different positions in the sample (wall, centre and at given radial distance). The recorded time–temperature profiles were compared with the prediction of a finite-element model assuming the linear temperature dependence of thermal diffusivity. Wall temperature data were used as a boundary condition. The difference between the measured and the calculated temperatures at the sample centre was minimised by the Marquardt Levenberg algorithm, giving optimal values of the model parameters A and B. Thermal diffusivity for both samples increased with temperature. The thermal diffusivity of mashed potatoes increased with pressure. The thermal diffusivity of olive oil decreased with pressure.

Keywords:

• thermal diffusivity
• olive oil
• mashed potatoes
• high pressure
• finite elements

Acknowledgements

This work was supported by the 6^th FP project NovelQ No. 015710 and the Food Research Institute Prague Institutional Grant No. MZe 0002702202.