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Journal of food physicsVol. 24-25. (2012.)


  • Andras S. Szabo :
    Quater of century has passed away after the chernobyl disaster3-5en [94.93 kB - PDF]EPA-02408-00006-0010

    Abstract: The disaster has happened in 1986 in the former Soviet Union, on the territory of northern Ukraine. In consequence of the nuclear plant accident a huge territory of Europe has been contaminated, including also Hungary. The contamination level of foodstuffs in Hungary within a few weeks after the disaster (dominantly 131-I) was significantly higher than the natural radioactivity (e.g. 40-K). Later the pollution level decreased and from 1990 the results of radiometric measurements have been proved that there is no significant difference in contamination (e.g. 137-Cs) of food and agricultural products before and after the nuclear disaster. The total radiation burden (partly from foodstuffs) of hungarian population (living appr. 1000 kilometres from the place of the accident) has been much less than the natural radiation load, so no increase of health risk has been determined in the 25 years period after the disaster.

    Keywords: disaster, natural radioactivity, radiometric measurements, contamination of food and agricultural products

  • Monika Božiková ,
    Peter Hlaváč :

    Abstract: Information about physical properties of whisky is almost impossible to find. That is why this paper is concerned with some physical properties of chosen types of whisky. Our research was focused on rheologic and thermal parameters. Temperature can be included between the most significant parameters that influence physical properties of food. And that is the reason why this article deals with chosen temperature dependencies of whisky rheologic and thermal properties. Temperature dependencies of whisky dynamic and kinematic viscosity can be described by decreasing exponential function and temperature dependency of whisky fluidity has increasing exponential character. Dependencies of thermal conductivity, diffusivity and volume specific heat on temperature are characterized by increasing linear function.

    Keywords: whisky, temperature, rheologic properties, thermophysical properties, relation

  • Peter Hlaváč ,
    Monika Božiková :

    Abstract: This article deals with thermophysical and rheologic properties which are very complicated characteristics of materials. For quality evaluation of food material is necessary to identify their physical properties. During processing of food materials we need to check their status step by step, in different parts of processing. For detection of food material status we could analyze chemical and physical properties. Chemical analyses usually take a longer time intervals than study of physical properties. In modern physical research there are often used dynamic methods of measurements, which are quicker than static methods. By using dynamic methods we can get characteristics of material in the short time. This fact is very important for the practice. Results of measurements are shown as graphical relations of rheologic and thermal properties to the temperature. Relations of dynamic and kinematic viscosity to the temperature are described by decreasing exponential function and dependency of beer fluidity on temperature has increasing exponential character. Dependencies of thermal conductivity and thermal diffusivity on temperature are characterized by increasing linear function.

    Keywords: beer, wort content, alcohol content, thermal parameters, rheologic parameters

  • Lenka Priatková ,
    Zuzana Hlaváčová ,
    Ákos Kertész :
    Electric properties utilization at quality of blueberry evaluation20-25en [211.96 kB - PDF]EPA-02408-00006-0040

    Abstract: Blueberries have become a product of interest in recent years due to their nutritional and health benefits. Electrical properties are important when processing foods involving electrical fields, electric current conduction, or heating through electromagnetic waves. These properties are also useful in the detection of processing conditions or quality of foods. Good correlations were obtained between dielectric properties measurements and human sensory analysis at the temperature 15 °C for the capacity range 640.98 nF to 1048.78 nF. The correlations, between human sensory and dielectric properties evaluation, show that in this range of capacity will be accepted as in the best quality by consumers.

    Keywords: blueberris, capacity, sensory analysis, quality

  • Dida Iserliyska ,
    Denisa Eglantina Duta ,
    Gábor Zsivanovits :

    Abstract: The effect of fibres and minerals on the quality of enriched bread was studied by means of consumer test for acceptance by elderly. Additionally rheological test was performed to determine the degree of elasticity of the enriched dough. The sensory and physical characteristics were established and evaluated.

    Keywords: flour, dough, bread, fibres, minerals, consumer test degree of elasticity

  • Zoltán Pék ,
    Hussein Daood ,
    Andrea Lugasi ,
    Lajos Helyes :

    Abstract: This study examined the feasibility of using non destructive, spectrophotometrical method to predict one of the most valuable internal quality indices, lycopene in individual tomato fruits. An open field experiment was conducted to study the effect of irrigation and potassium supplement on the yield and lycopene content of processing tomato fruit. Three different treatments (regularly irrigated RI, irrigation cut-off 30 days before harvest CO, and rainfed RF unirrigated control) and two different K fertilisations (P) were applied. Regular irrigation significantly decreased the lycopene content of tomato fruits. The CO treatment resulted in the highest total lycopene without additional potassium supplement. Potassium supplement given at the time before fruit maturity significantly increased the lycopene concentration of cultivar Brigade, independently of irrigation. The closest correlation was at 700nm R2=0.39 and R2=0.50, between reflectance and the (all-E)-lycopene and the (9Z)+(13Z)- lycopene isomers respectively.

    Keywords: tomato, lycopene, (all-E)-(9Z)-(13Z)-lycopene isomers, irrigation

  • G. Zsivanovits ,
    B. Brashlyanova ,
    O. Karabadzhov :

    Abstract: Heat pumps have been known to be energy efficient when used in conjunction with drying operations. The principal advantages of heat pump dryers (HPD) emerged from the ability of heat pumps to recover energy from the exhaust as well as their ability to control the drying gas temperature and humidity. It is a low temperature (40-45°C) drying system, which can preserve the nutrition parameters of the raw material, but can produce a dried product, with high level of microbiological and shelf-life stability and safety. The apple slices were dried for five hours, till equilibrium dry content. The received product has low moisture (about 85 % dry base) which is good for longer shelf-life. Dielectric parameters (between 20Hz and 10MHz), volume and weight of the dried apple slices were investigated in every hour. The aim of the experiment series was to see, if the method of dielectric spectroscopy is useful to follow the drying process. To analyse the data in function of drying time non-linear (sigmoid) regression was used and linear correlation matrix was created between the measured parameters. The highest correlations are marked in the tables.

    Keywords: impedance parameters, non-linear regression, drying trends, correlation matrix, gentle drying

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