Abstract

YANEZ-LIMON, J.M. et al. Thermal diffusivity studies in edible commercial oils using thermal lens spectroscopy. Superf. vacío [online]. 2005, vol.18, n.1, pp.31-37. ISSN 1665-3521.

The thermal diffusivity of edible commercial oils (canola, peanut, olive, sunflower, maize and soy bean) was determined using thermal lens spectroscopy in the unmatched mode. The measurements were made using the 632.8 nm He-Ne and 488 nm Ar laser beams as the probe and excitation beams, respectively. The thermal lens effect (∆Ι) showed a strong dependence on the thermo-optical properties of these oils. This fact was used to construct a curve in which each oil is distinguished by its thermal lens signal for a given constant excitation beam power.

Thermal diffusivity as a function of temperature increased significantly for the samples with lower thermal diffusivity (soy bean and canola) at around T=32ºC. This parameter was constant from 32ºC until 58ºC and increased at about 72ºC for the soy bean case.These results were compared using principal component analysis (PCA) of near infrared spectra. The spectra information was analyzed using PCA to classify oils under heat treatment and to relate the different groups in terms of thermal diffusivity.

Keywords : Optical properties; Thermal diffusivity; Thermal lens; Edible oils.

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