Instytut Podstawowych Problemów Techniki

Streszczenie:

At present, the problem of identifying and controlling different types of Mechanically
Separated Meat (MSM) is a very important practical issue in the meat industry. To address this
challenge, the authors propose a new, analytical method for the discrimination and characterization
of MSM that uses density measurements. The method proposed by the authors, in contrast to the analytical methods existing so far, is rapid, non-destructive, relatively simple and can be computerized.
The density measurements of meat samples were conducted with a modified pycnometric method.
Statistically significant (p < 0.01) differences were found in the evaluated mean values of density
for all investigated types of meat. Subsequently, the density measurements were correlated with
the physicochemical properties of meat samples. A high correlation coefficient was found between
the density of meat samples and the content of protein, sodium and fat. The authors have proven
that density measurements allow for rapid discrimination of various types of MSM, and can also be
effectively used to determine the chemical composition of MSM samples, e.g., the content of protein,
fat and sodium.

Słowa kluczowe:

Meat density; Mechanically Separated Meat (MSM); protein content; fat content; Sodium (Na) content; Calcium content (Ca)

Afiliacje autorów:

Streszczenie:

An innovative analytical ultrasonic method for identification and investigation of Mechanically Separated Meat (MSM) samples is presented. To this end, the ultrasonic wave velocity (f = 5 MHz) in the investigated meat samples was measured. The measured ultrasonic velocity ranged from 1553.4 to 1589.9 m/s. The investigations were performed for: 1) minced hand deboned chicken fillets, 2) low pressure MSM from chicken carcasses, 3) low pressure MSM from chicken collarbones, 4) high pressure MSM from chicken carcasses and 5) high pressure MSM from chicken collarbones. Statistically significant (p < 0.001) differences in the ultrasonic velocity were observed for each of investigated kinds of meat. High significant correlations were found between the ultrasonic velocity and the content of protein, fat, sodium and density of the investigated meat. The applicability of the developed ultrasonic method for identifying various kinds of meat and to determine the content of protein, fat, sodium and density was demonstrated.

Słowa kluczowe:

physicochemical parameters, mechanically separated meat, ultrasonic velocity, protein content, calcium content, fat content

Afiliacje autorów:

Streszczenie:

An emerging ultrasonic technology aims to control high-pressure industrial processes that use liquids at pressures up to 800 MPa. To control these processes it is necessary to know precisely physicochemical properties of the processed liquid (e.g., Camelina sativa oil) in the high-pressure range. In recent years, Camelina sativa oil gained a significant interest in food and biofuel industries. Unfortunately, only a very few data characterizing the high-pressure behavior of Camelina sativa oil is available. The aim of this paper is to investigate high pressure physicochemical properties of liquids on the example of Camelina sativa oil, using efficient ultrasonic techniques, i.e., speed of sound measurements supported by parallel measurements of density. It is worth noting that conventional low-pressure methods of measuring physicochemical properties of liquids fail at high pressures. The time of flight (TOF) between the two selected ultrasonic impulses was evaluated with a cross-correlation method. TOF measurements enabled for determination of the speed of sound with very high precision (of the order of picoseconds). Ultrasonic velocity and density measurements were performed for pressures 0.1–660 MPa, and temperatures 3–30 °C. Isotherms of acoustic impedance Za, surface tension σ and thermal conductivity k were subsequently evaluated. These physicochemical parameters of Camelina sativa oil are mainly influenced by changes in the pressure p, i.e., they increase about two times when the pressure increases from atmospheric pressure (0.1 MPa) to 660 MPa at 30 °C. The results obtained in this study are novel and can be applied in food,and chemical industries.

Słowa kluczowe:

ultrasonic methods, speed of sound, acoustic impedance, surface tension, thermal conductivity, physicochemical properties

Afiliacje autorów:

Streszczenie:

Modeling of high-pressure technological processes in the food industry requires knowledge of thermophysical parameters of processed foodstuffs in a broad range of pressures and temperatures. However, the high-pressure thermophysical parameters of foodstuffs are very rarely published in the literature. Therefore, further research is necessary to achieve a deeper insight into the biophysical and thermophysical phenomena under pressure to provide better control of technological processes and optimize the effects of pressure. The essential goal of this work is to evaluate the impact of high pressure and temperature on the thermophysical parameters of liquid foodstuffs on the example of diacylglycerol (DAG) oil (which attracted recently a considerable attention from research and industrial communities due to its remarkable benefits for health), using ultrasonic wave velocity and density measurements. Isotherms of adiabatic and isothermal compressibility, isobaric thermal expansion coefficient, internal pressure, and thermal pressure coefficient versus pressure were evaluated, based on the measurement of the compressional ultrasonic wave velocity and density of DAG oil at high pressures (up to 500 MPa) and at various temperatures. The adiabatic compressibility is affected mostly by the changes of pressure, i.e., it grows about four times when the pressure increases from the atmospheric pressure (0.1 MPa) to 400 MPa at a temperature of 50 °C. By contrast, the internal pressure is a pronounced function of the temperature, i.e., it increases six times when the temperature rises from 20 to 50 °C at a pressure of a 200 MPa. To perform numerical calculations, it was convenient to introduce a Tammann–Tait type equation of state to approximate the measured density isotherms of the investigated DAG oil. The results obtained in this paper can be applied in modeling and optimization of high-pressure technological processes and processing of foodstuffs. Evaluation of high-pressure isotherms of the considered thermophysical parameters of the DAG oil is an original authors' contribution to the state-of-the-art.

Słowa kluczowe:

high-pressure food processing, diacylglycerols, thermophysical parameters, isothermal compressibility, isobaric thermal expansion coefficient, ultrasonic methods

Afiliacje autorów:

Streszczenie:

Investigation of the high-pressure thermophysical properties of biofuels, e.g., bulk modulus, Surface tension, and viscosity is of paramount importance in fuel injection systems in diesel engines. Another crucial and dangerous phenomenon that may occur in biofuels at high pressures is phase transition (solidification), which can drastically increase the viscosity of the biofuel. This effect may hamper proper operation of the engine, especially under cold-start conditions. Unfortunately, the availability of highpressure thermophysical properties of biofuels is still limited. The goal of this paper is to investigate the impact of high pressures on thermophysical properties of biofuels on the example of rapeseed fatty acid methyl esters (RME) in a wide range of pressures (0:1 to 250 MPa) and temperatures (5 to 20 _C). To this end we employed innovative ultrasonic techniques, i.e., the Bleustein-Gulyaev surface acoustic waves for measuring RME viscosity, and ultrasonic bulk compressional waves for measuring sound velocity in RME and consequently evaluating RME thermophysical parameters, e.g., bulk modulus and surface tension. The viscosity of the measured RME displayed an abrupt increase at pressures: 260 MPa (t Ľ 20 _C), 230 MPa (t Ľ 15 _C), 190 MPa (t Ľ 10 _C), and 130 MPa (t Ľ 5 _C). Evidently it was a signature of the phase transition (solidification) occurring in the RME. The discovered high viscosity high-pressure phase in RME can be very detrimental for operation of modern common rail Diesel engines. Therefore, the results of research presented in this paper should be interesting for engineers and designers working with modern common rail Diesel engines using biofuels.

Słowa kluczowe:

Biofuels, Methyl esters, Phase transitions, Viscosity, Speed of sound, Ultrasonic methods, High pressure

Afiliacje autorów:

Streszczenie:

High-pressure processing is a powerful technology for food preservation. The knowledge of foods properties in the high-pressure range is important to develop and optimize such processes by means of mathematical modeling and simulation. Ultrasonic methods are rapid, non-invasive and can be used to characterize foods like edible oils (e.g., composition, purity, and quality assessment). In this paper, they were applied for the investigation of physicochemical properties of olive oil at high pressure at different temperatures. The sound wave velocity was measured by the pulse-transmission method and the corresponding oil density was additionally determined from the monitoring of sample volume change. Measurements were conducted in the pressure range up to 600 MPa, for temperatures from 20 to 50°C. Intermolecular free length, isothermal and adiabatic compressibility versus pressure were calculated using measured sound speed and density isotherms. Discontinuities in the measured isotherms of sound speed and density versus pressure indicate the presence of liquid-to-solid phase transitions. The kinetics of the liquid-to-solid phase transition was also investigated. The transformation times of olive oil augment with increasing temperature. This study can be broadened to other liquid foodstuffs to investigate the influence of temperature on their physicochemical properties at high pressure.

Słowa kluczowe:

Physicochemical properties, Intermolecular free length, Ultrasonic velocity, High-pressure food processing, Olive oils

Afiliacje autorów:

Streszczenie:

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.

Słowa kluczowe:

Vegetable oils, Sound velocity, Triacylglycerols, Phase transition, High pressure

Afiliacje autorów:

Streszczenie:

In this article, the influence of high pressure on sound velocity at 293 K has been presented. The investigated diacylglycerol oil (DAG – [D82T18]AG) was composed of 82% DAGs and 18% triacylglycerols. The variation of sound velocity with hydrostatic pressure for DAG was evaluated up to 400 MPa. The phase transformation in DAG has been observed as a discontinuity of the dependence of sound velocity on pressure. The sound velocity during the phase transition has shown distinct increment. Also the volume changes have been measured. It has shown the rapid drop of the volume at the phase transformation pressure due to the possible crystallization of DAG oil.

Słowa kluczowe:

high pressure, velocity, DAG

Afiliacje autorów:

Streszczenie:

The influence of high pressure on viscosity and compressibility of diacylglycerol (DAG) oil has been presented in this paper. The investigated DAG oil was composed of 82% of DAGs and 18% TAGs (triacylglycerols). The dynamic viscosity of DAG was investigated as a function of the pressure up to 400 MPa. The viscosity was measured by means of the surface acoustic wave method, where the acoustic waveguides were used as sensing elements. As the pressure was rising, the larger ultrasonic wave attenuation was observed, whereas amplitude decreased with the liquid viscosity augmentation. Measured changes of physical properties were most significant in the pressure range near the phase transition. Deeper understanding of DAG viscosity and compressibility changes versus pressure could shed more light on thermodynamic properties of edible oils.

Słowa kluczowe:

DAG viscosity, compressibility, phase transitions, transmitted and scattered light

Afiliacje autorów:

Streszczenie:

In this paper, phase transitions in diacylglycerol (DAG) oil are investigated by using an ultrasonic method for measuring viscosity. Viscosity of diacylglycerol (DAG) oil is measured over a wide range of hydrostatic pressures up to 500 MPa, and at temperatures ranging from 10 to 40 °C. The observed discontinuities in the viscosity versus pressure curves (isotherms) indicate phase transitions. An original ultrasonic method that uses the surface acoustic Bleustein–Gulyaev (B–G) wave was employed to measure the viscosity of DAG oil at high pressure range. This method allows for fast and reliable measurement of DAG oil viscosity along various isotherms. Moreover, the kinetics of the observed phase transformations at various temperatures was analyzed. The results of the study are a novelty, and can be helpful in evaluating the physicochemical properties of edible oils.

Słowa kluczowe:

Edible oils, Ultrasonic methods, Diacylglycerols, Viscosity, Phase transitions, High pressure

Afiliacje autorów:

Streszczenie:

In many technological processes liquids are subjected to high pressures (up to 800 MPa), e.g., in high pressure preservation of liquid foodstuffs. Similarly, in modern fuel injection systems for diesel engines, biofuels are subjected to pressures up to 300 MPa. In such severe conditions, thermophysical properties of liquid change considerably. Conventional methods for measuring thermophysical properties of liquids completely fail at high pressure conditions. Hence, these methods are of no use in real industrial conditions, during on-line monitoring of industrial processes. Thus, there exist a strong demand for industrial grade measurements methods, which can be used to monitor on-line the actual parameters of liquids. A very promising solution is offered by ultrasonic techniques which are particularly suitable for measurements of thermophysical properties of liquids at high pressures. In addition, the ultrasonic methods (that use low-intensity ultrasonic waves) are totally non-destructive and can be fully automated in real time.

Słowa kluczowe:

ultrasonic methods, thermophysical properties, high pressure, acoustic impedance, thermal conductivity

Afiliacje autorów:

Streszczenie:

In many industrial technological processes, liquids are subjected to high pressures, e.g., in the high pressure food preservation. Similarly, in modern fuel injection systems for diesel engines, biofuel is subjected to a pressure up to 300 MPa. In such conditions, in liquids, high-pressure phase transitions (solidification) can occur that substantially increase the density and liquid viscosity. This solidification can result in significant problems with engine failure under cold-start conditions. This is an evident recipe for disaster, since the engine and its accessories would be very likely quickly destroyed. Thus, it is important to determine at what pressures and temperatures phase transitions occur. Conventional mechanical methods for measuring physicochemical properties of liquids at these extreme conditions do not operate. By contrast, ultrasonic techniques are very suitable for measurements of hysicochemical properties of liquids at high pressure, since they are non-destructive, can be fully automated and are characterized by the absence of moving parts. The aim of this work is to study the high-pressure hysicochemical properties of liquids (exemplified by a Camelina sativa - false flax oil) using novel ultrasonic methods.

Słowa kluczowe:

pressure, ultrasonic methods, phase transitions, Camelina sativa

Afiliacje autorów:

Streszczenie:

The fundamental goal of this work is to verify the hypothesis of the existence of high-pressure phase transitions in biofuel components on the example of rapeseed fatty acid methyl esters (RME), by using ultrasonic methods. in a wide range of pressures (from atmospheric pressure to 300 MPa) and for various temperatures from 5 to 20 °C. Investigation of phase transitions in biofuels at high pressures is of great importance in the design of injection systems in modern diesel engines (common rail). Direct examination of phase transitions in liquids under high pressure, using classical methods, is very difficult. To overcome this disadvantage, the authors applied ultrasonic methods (viscosity measurement), which in contrast to the classical methods allow in a relatively simple way the investigation of high-pressure properties of liquids. Viscosity was measured by the original method that uses ultrasonic surface waves of the Bleustein-Gulyaev type, developed by the authors at the Institute of Fundamental Technological Research in Warsaw. From the measured viscosity isotherms, the occurrence of high-pressure phase transitions in methyl esters were evaluated.

Słowa kluczowe:

high-pressure phase transitions, biofuels, ultrasonic Bleustein-Gulyaev waves, viscosity measurements

Afiliacje autorów:

Streszczenie:

The aim of the study was to investigate the phase transitions in biofuel components by using ultrasonic methods on the example of methyl esters of fatty acids, in a wide range of pressures (from atmospheric pressure to 400 MPa) and for various temperatures from 5 to 20 °C. Investigation of phase transitions in biofuels at high pressures is of great importance in the design of injection systems in modern diesel engines (common rail). Direct examination of phase transitions in liquids under high pressure, using classical methods, is very difficult. To overcome this disadvantage, the authors applied ultrasonic methods (viscosity measurement), which in contrast to the classical methods allow in a relatively simple way the investigation high-pressure properties of liquids. Viscosity was measured by the original method that uses ultrasonic surface waves of the Bleustein-Gulyaev type, developed by the authors at the Institute of Fundamental Technological Research in Warsaw. From the measured viscosity isotherms, the occurrence and kinetics of high-pressure phase transitions in methyl esters were evaluated.

Słowa kluczowe:

High pressure phase transitions, physicochemical parameters of biofuels, ultrasonic viscosity measurements, rapeseed methyl esters

Afiliacje autorów:

Streszczenie:

High pressure research of the physicochemical properties of liquids has been stimulated by the fast development of such technologies as biodiesel production, high-pressure food processing and conservation, modification of biotechnological properties. Monitoring and studying liquid viscosity and ultrasonic wave velocity in liquids as a function of pressure and temperature enable to evaluate many important physicochemical parameters of liquids. These methods allow also insight into the phenomena governing the microstructural modifications occurring in treated substances, i.e. phase transitions. The knowledge of physicochemical properties (e.g. density, relaxation time, internal pressure or free volume) of pressurized substances is essential for understanding, design and control of the process technology. Measurements were conducted on the example of diacylglycerol oil (DAG oil), that is an important constituent of oils and fats.

Słowa kluczowe:

Physicochemical parameters of liquids, high pressure, ultrasonic velocity, viscosity of liquids, DAG oil

Afiliacje autorów:

Streszczenie:

Podstawowym celem tej pracy jest przedstawienie możliwości zastosowania fal ultradźwiękowych do badania właściwości produktów spożywczych. Omówione zostaną rodzaje fal ultradźwiękowych (podłużne oraz poprzeczne) oraz ich rozchodzenie się w ciekłych oraz stałych produktach spożywczych (tj. w olejach oraz produktach mięsnych). Przedstawione będą nowe niespotykane właściwości fal ultradźwiękowych, które rozchodzą się w ciałach stałych oraz cieczach.
Na podstawie zmierzonych izoterm prędkości stwierdzono występowanie wysokociśnieniowych przemian fazowych w olejach roślinnych. Wyznaczenie pod wysokim ciśnieniem (do 600 MPa) parametrów fizykochemicznych olei roślinnych (czyli np. modułu objętościowego oraz napięcia powierzchniowego) oraz wykrycie oraz zbadanie wysokociśnieniowych przemian fazowych w olejach roślinnych jest nowością.
Z drugiej strony, identyfikacja różnych rodzajów mięsa metodami ultradźwiękowymi (tj. stosując pomiary prędkości fal ultradźwiękowych) jest także nowością i pozwala w sposób relatywnie prosty identyfikować różne rodzaje mięsa, tj. mięso oddzielone ręcznie od mięsa otrzymanego mechanicznie (MOM) czyli MOM niskociśnieniowy oraz MOM wysokociśnieniowy od mięsa wykrawanego ręcznie.
Badania przeprowadzone zostały przy współpracy autorów z Instytutu Podstawowych Problemów Techniki PAN oraz Instytutu Biotechnologii Przemysłu Rolno Spożywczego w Warszawie.

Słowa kluczowe:

Podłużne fale ultradźwiękowe, Prędkosć fazowa, Prędkość grupowa, Produkty spożywcze

Afiliacje autorów:

Streszczenie:

Prezentacja dotyczy badania wysokociśnieniowych parametrów fizykochemicznych olejów roślinnych. Badania wykonano na przykładzie oleju z lnianki siewnej (Camelina sativa). Olej z lnianki siewnej znalazł zastosowanie w wielu dziedzinach przemysłu takich jak: spożywczy, farmaceutyczny, kosmetyczny. Olej z lnianki siewnej stosowany jest również jako surowiec do produkcji biopaliw. Te biopaliwa mogą być zastosowane do napędu samolotów odrzutowych (np. F-18 Hornet, Boeing 747, Airbus A-320). Zaletą tych biopaliw jest niska emisyjność czynników szkodliwych dla środowiska (np. dwutlenku węgla). Znajomość parametrów fizykochemicznych olejów jest niezbędna w projektowaniu wysokociśnieniowych procesów technologicznych przetwarzania i konserwacji żywności. Pomiar tych parametrów fizykochemicznych cieczy w zakresie dużych ciśnień metodami klasycznymi jest bardzo trudny prawie niemożliwy. Rozwiązaniem problemu może być zastosowanie metod ultradźwiękowych. Metody ultradźwiękowe dają się z powodzeniem zastosować do pomiaru tych parametrów fizykochemicznych w zakresie dużych ciśnień. Stosują metody ultradźwiękowe (tj. pomiar prędkości dźwięku wraz z równoległym pomiarem gęstości oleju) wyznaczono następujące parametry fizykochemiczne oleju z lnianki siewnej:
1) ściśliwość adiabatyczną β_a
2) ściśliwość izotermiczną β_T
3) współczynnik rozszerzalności cieplnej α_p
4) ciepło właściwe c_p
5) napięcie powierzchniowe σ
6) przewodność cieplną k
7) współczynnik wyrównywania temperatury (dyfuzyjność cieplną) a.
Pomiary wykonano w zakresie ciśnień od ciśnienia atmosferycznego do 650 MPa oraz dla wartości temperatur od 3 °C do 30 °C. Uzyskane wyniki są oryginalne i nowatorskie i mogą być zastosowane w przemyśle spożywczym i chemicznym.

Słowa kluczowe:

Parametry fizykochemiczne, Olej z Camelina Sativa, Wysokie ciśnienia

Afiliacje autorów:

Streszczenie:

Knowledge of high-pressure behavior of the processed liquids is necessary to control technological processes in many branches of industry (e.g., in chemical, pharmaceutical and food industries). However, data on high-pressure behavior of liquids are still incomplete. The aim of this study is to investigate the high-pressure behavior (i.e., thermopysical parameters and possible high-pressure phase transitions) of liquids (on the example of Camelina sativa oil), applying ultrasonic methods (i.e., sound velocity and parallel density measurements). Camelina sativa (false flax) oil has found application in many branches of industry as well as a raw material for biofuel production. Generally, conventional methods for measuring thermophysical properties of liquids fail at high pressures. The solution to the problem can be the use of ultrasonic methods. Ultrasonic measurements were performed at f = 5 MHz for pressures 0.1 - 660 MPa, and for temperatures 3 - 30 ºC. Pronounced high-pressure phase transitions were discovered by the authors in Camelina sativa oil. The use of ultrasonic methods has enabled the determination of many physicochemical parameters of Camelina sativa oil, such as: 1) adiabatic compressibility β_a, 2) thermal expansion coefficient α_p, 3) specific heat at constant pressure c_p, 4) thermal conductivity k and 5) thermal diffusivity a. The results obtained in this study are novel and can be employed to design and control technological processes in many branches of industry

Słowa kluczowe:

Ultrasonic methods, high pressure, thermophysical properties, Camelina sativa

Afiliacje autorów:

Streszczenie:

W tej pracy przedstawione zostały wyniki badań właściwości fizykochemicznych oleju z lnianki siewnej (Camelina sativa) w zakresie dużych ciśnień. Olej z lnianki siewnej znalazł zastosowanie w wielu dziedzinach przemysłu takich jak: spożywczy, farmaceutyczny, kosmetyczny. Olej z lnianki siewnej stosowany jest również jako surowiec do produkcji biopaliw. Te biopaliwa mogą być zastosowane do napędu samolotów odrzutowych (np. F-18 Hornet, Boeing 747, Airbus A-320). Zaletą tych biopaliw jest niska emisyjność czynników szkodliwych dla środowiska (np. dwutlenku węgla). Znajomość parametrów fizykochemicznych olejów jest niezbędna w projektowaniu wysokociśnieniowych procesów technologicznych przetwarzania i konserwacji żywności. Pomiar tych parametrów fizykochemicznych cieczy w zakresie dużych ciśnień metodami klasycznymi jest bardzo trudny prawie niemożliwy. Rozwiązaniem problemu może być zastosowanie metod ultradźwiękowych. Metody ultradźwiękowe dają się z powodzeniem zastosować do pomiaru tych parametrów fizykochemicznych w zakresie dużych ciśnień. Stosują metody ultradźwiękowe (tj. pomiar prędkości dźwięku wraz z równoległym pomiarem gęstości oleju) wyznaczono następujące parametry fizykochemiczne oleju z lnianki siewnej: 1) ściśliwość adiabatyczną β_a 2) ściśliwość izotermiczną β_T 3) współczynnik rozszerzalności cieplnej α_p 4) ciepło właściwe c_p 5) napięcie powierzchniowe σ 6) przewodność cieplną k 7) współczynnik wyrównywania temperatury (dyfuzyjność cieplną) a. Pomiary wykonano w zakresie ciśnień od ciśnienia atmosferycznego do 650 MPa oraz dla wartości temperatur od 3 °C do 30 °C. Uzyskane wyniki są oryginalne i nowatorskie i mogą być zastosowane w przemyśle spożywczym i chemicznym.

Afiliacje autorów:

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:

Streszczenie:

The aim of this work was to evaluate the impact of temperature and high pressure on thermophysical properties of liquids, exemplified by a Camelina sativa (false flax) oil. Camelina sativa oil has gained recently a growing interest due to its health-promoting effect as well as for its potential use in biodiesel production. To achieve the above objective, we measured the speed of sound and density in the selected oil. The speed of sound is directly associated to many thermophysical parameters of liquids. Hence, measurements of ultrasonic longitudinal wave velocity (f = 5 MHz) and liquid density, as a function of pressure and temperature, allowed determination of several important thermophysical parameters of the investigated liquid. The speed of sound in the liquid was determined from the time of flight measured with the cross-correlation method. To perform numerical calculations, it was helpful to introduce a Tammann–Tait type equation of state to approximate the measured density isotherms of the investigated Camelina sativa oil.

Słowa kluczowe:

Speed of sound, high pressure, cross-correlation method, thermophysical parameters, Camelina sativa oil

Afiliacje autorów:

Streszczenie:

Background, Motivation and Objective: In many industrial technological processes, liquids are subjected to high pressures, e.g., in the high pressure food preservation. Similarly, in modern fuel injection systems for diesel engines, biofuel is subjected to a pressure up to 300 MPa. In such conditions, in liquids, phase transitions can occur that substantially increase the density and liquid viscosity. This can be very detrimental for the engine or the technological equipment. Thus, it is important to determine at what pressures and temperatures phase transitions occur. Conventional mechanical methods for measuring physicochemical properties of liquids at these extreme conditions do not operate. By contrast, ultrasonic techniques are very suitable for measurements of physicochemical properties of liquids at high pressure, since they are non-destructive and can be fully automated. The aim of this work is to study the high-pressure physicochemical properties of liquids (exemplified by a camelina sativa - false flax oil) using novel ultrasonic methods.

Słowa kluczowe:

High pressure, Biofuels, Viscosity, Phase transitions

Afiliacje autorów: