An application of the laser induced photopyroelectric effect for measuring the thermal effusivity of some (semi)liquid foodstuffs

摘要

The photopyroelectric calorimetry, in the front (inverse) configuration, was applied in order to measure the thermal effusivity of some Brazilian fats. The front configuration with thermally thick sensor and sample, and optically opaque sensor, was used for the first time for analysing the thermal properties of fat products. The information was obtained via a frequency scan of the phase of the pyroelectric signal; the measurement needs no calibration. The main advantage of this configuration on the other two front schemes proposed before is mainly technical: one has not to use very thin foils or expensive semitransparent sensors. On the other hand, the information is contained in the phase of the signal (and not in the amplitude - as usual) which is not dependent on the power fluctuations of the radiation source.