Streszczenie:
The presentation includes an overview of the ultrasonic methods used to investigate the thermophysical properties of edible oils in the high pressure range. Using ultrasonic waves we can determine (relatively easily) a number of physicochemical parameters of edible oils in the range of high pressures. On the other hand, the determination of these high pressure parameters using classical measurement methods (e.g., calorimetry, Fourier transform infrared spectroscopy) is very difficult, practically impossible. The basic ultrasonic measurements are measurements of velocity and attenuation of the ultrasonic wave. A brief description of the properties and parameters describing ultrasonic waves will be presented. The most important thermophysical parameters of oils include: 1) adiabatic and isothermal compressibility; 2) thermal expansion coefficient; 3) specific heat at constant pressure 4) surface tension; 5) viscosity, 6) thermal pressure coefficient and 7) thermal conductivity. The knowledge of these physicochemical parameters of oils high pressures for various temperature values is essential in the design and optimization of high-pressure technological processes of food preservation and food processing. Particularly difficult (using classical measurement methods) is to measure the viscosity of oils under high pressure. The application of the ultrasonic surface wave method of Love or Bleustein-Gulyaev type (developed at the Institute of Fundamental Technological Research of the Polish Academy of Sciences) solves this problem, allowing determination of oil viscosity for pressures above 200 MPa (up to 800 MPa). An interesting phenomenon that we can investigate by ultrasonic methods are the high-pressure phase transitions in edible oils. Using ultrasonic methods, high pressure phase transformations in many edible oils (e.g., in olive oil, in rapeseed oil, and in Camelina sativa oil) were detected and investigated. Camelina sativa oil is a very promising raw material for the production of biofuels. It is practically impossible to investigate these high pressure phase transformations in edible oils using classical measurement methods. Application of ultrasonic measurement methods enables the investigation of the physicochemical properties of edible oils (liquids) under high pressure.
Słowa kluczowe:
Thermophysical parameters, ultrasonic methods, edible oils, high-pressure
Afiliacje autorów:
Kiełczyński P. | - | IPPT PAN |
Ptasznik S. | - | Air Force Institute of Technology (PL) |
Kalinowski A. | - | Institute of agricultural and food biotechnology (PL) |