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The paper presents compressibility studies of some vegetable oils within the range of 1 GPa. The measurements of the volume were done for rapeseed oil, soy oil, sunflower oil and linseed oil at constant temperature. On this basis, the modified Tait equation coefficients were evaluated. In the case of rapeseed oil, soy oil and sunflower oil, the discontinuity of P-V characteristics for phase transition has been observed. The value of Tait coefficients for the pressure above the phase transition suggests that the high-pressure phase is solidified. The experiment was conducted with a computer-based data acquisition system with software written in National Instruments LabVIEW™ graphical programming language. Piston displacement was measured by electronic digital calliper with RS232 interface.

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This paper presents measurements of sound velocity and attenuation in olive oil, with known chemical composition, as a function of pressure, within the range of pressure up to 0.7 GPa. Dependencies of sound velocity, relative ultrasonic wave attenuation, volume, and adiabatic compressibility on pressure show discontinuities. This proves the existence of the first order phase transition in olive oil (liquid to solid-like phase transition). Rapid and large changes in relative attenuation testify to the existence of a phase transition in olive oil. Moreover, the kinetics of phase transition was also investigated. Measurement of acoustic wave velocity and relative attenuation in olive oil during the phase transition and in the high-pressure phase is a novelty. The results obtained can be useful in the development of new methods in food (edible oils) control, processing, and preservation.