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Journal of food physicsVol. 21. (2008.)


  • Ginka Antova ,
    Tanya Nenkova :

    Abstract: The effect of microwave heating on some physicochemical parameters and oxidative stability of two sunflower oil (oleic and linoleic type), which have different lipid composition was studied. Each oil was heated by microwave energy of 360, 600 and 900W for 3, 6, 9 and 12 minutes. The results were juxtaposed to the ones, received by conventional heating and duration of 18 minutes. It was determined that by microwave and conventional heating of 900W for of sunflower oil no hydrolysis processes are observed. The oxidation degree in both types of oil increases with the increase of energy and the duration of microwave heating. The peroxide value and the conjugated dienes after 12 min of microwave heating at maximum power increase about 2 times, irrelevant of the fact that the two types of oil have a different oxidation stability and different degree of oxidation. The colour value increases, and the quantity of tocopherols decreases about 1.5 times. The nature of the oxidation changes in conventional heating does not differ significantly from those in microwave heating.

  • T. Bineva ,
    D. Staneva ,
    I. Yordanova ,
    N. Stoeva :

    Abstract: Vegetation pot experiments with spring barley, cultivar Obzor were carried out. The plants were grown under controlled conditions and in the phase of “stem extension” were irradiated with Cs-137 gamma rays at a dose of 5 Gy and dose intensity of 2 Gy/min.
    On the day following the irradiation the plants were sprayed with synthetic growth regulators for the purpose of reducing the irradiation damage. Two types of protectors were tested: 4-Сhlorophenoxyacetic acid and Phloroglucinol – in concentration of 10-3 M. The degree of the irradiation damage and protection was recorded at the end of the vegetation period following some productivity indexes. The coefficient of protection of the applied modifiers was also determined.
    It was established that in case of irradiation of spring barley with a dose of 5 Gy in the phase of stem extension, the reproductive organs were strongly damaged, which led to a considerable reduction of plant productivity. The application of growth regulators after the irradiation improves to a different degree some of observed indexes, as a result of which the plant productivity is increased about 18% after treated with 4-Сhlorophenoxyacetic acid.

  • P. Břenek ,
    M. Jůzl ,
    K. ©ustová :

    Abstract: In this work are described results of first year of research of spectrofotometric measuring of colour. We observed an improvement of instrumental measuring of colour as a marker of origin of some varieties of potatoes.
    We tested ten varieties of potatoes. The potatoes were tested raw and boiled. Three raw potato tubers were parted in two pieces in transverse and lengthwise direction. Every half was measured in three repetition. In the same way were prepared other three raw and three boiled potatoes which were measured over the PE sheeting..
    The optical system is using diffused illustration and reflected light is measured under coal 8°(d/8) with SCE function (specular component excluded) for elimination of mirror radiance. Slot diameter is 30 nm..
    All spectrum between 380-780 nm was measured. The colour is defined in L*a*b* colour system (CIELab)..
    The first record shows that it is possible to diagnose the varieties of potatoes only by spectrophotometical measuring of colour. Just now we are trying to confirm this in other tests in In-house grant of Mendel University.

  • J. Buchar ,
    ©. Nedomová ,
    D. Trnka ,
    P. Dvořáková ,
    L. Severa :
    Several acoustics method of the cheese ripening evaluation20-24en [241.65 kB - PDF]EPA-02408-00003-0060

    Abstract: The paper is focused on the study of the feasibility of using the acoustic impulse-response technique to evaluate Edam cheese texture and maturity. Cheese blocks were hit with an impact bar and the acoustic response at the eight points on the cheese surface was recorded. The response signals (impact force, surface displacement and surface velocities) were detected by the laservibrometers. In connection with the results of the classical compression tests performed on the tested cheeses the constitutive equation of the cheese behaviour has been designed. This equation has been used in the numerical simulation of the cheese block response. This simulation has been performed using of the LS DYNA 3D finite element code. The numerical results show reasonable agreement with experimental ones.

  • Fredijs Dimins ,
    Peteris Kuka ,
    Ilze Cakste ,
    Ingrida Augspole :

    Abstract: For the characteristic of honey quality it is possible to use different physical and chemical parameters. For example, activity of enzymes, the content of sugars, etc. The content of carbohydrates in honey is very diverse. It depends on kinds of honey and many other things factors. The content of sugars in honey allows define quality of honey and also characterizes specific properties of honey. Activity of enzyme invertase also as activity of enzyme amylases depends from heating and storage of honey. Therefore invertase can serve as a parameter of quality of honey. Amino acid proline is one of the main amino acids of honey. Natural honey should contain this acid. Therefore definition the content of proline in honey can serve as a parameter of quality of honey. Each carbohydrate has a specific angle of rotation of polarized light (specific rotation). It depends on relations and content of carbohydrates in honey.

  • Füstös Zsuzsanna ,
    Gilingerné Pankotai Mária ,
    Felföldi József ,
    A. K. El-Beik :

    Abstract: The aim of our research was to study the effect of the different storage system different post-harvest handling for the 4 type of sweet melon varieties in different maturity stage on different storage temperature (4 and 8 oC) for the storability measured on different way and test the change sugar content storage. The storage results of different variety shown clearly the long-shelf life varieties were Main results of our research work was the evaluation of the storage results of the melon fruits which were harvested in different maturity stage. Results of dropping-treatment, model of ill-treatment shown dramatically deterioration loss.

  • D. I. Hilmanovich ,
    A. R. Genselevich :
    Learning of physicochemical parameters of the sausage goods36-37en [74.13 kB - PDF]EPA-02408-00003-0110

    Abstract: Meat products are one of the major foods, containing majority of nutrients necessary for a man. Therefore monitoring of meat's quality and meat's products is one of the priorities of the branch. During the done work was learned such methods as: Moisture definitions in different breeds of sausage goods. Definition pH of a sausage meat by the colorimetric method (tracer method). Definition of calcium content in meat products by the chelatometry method and potentiometric titration. During done work regularities in changes of moisture content, calcium and pH in different breeds of producers of sausage goods were made. Calcium is contained in meat in free and bound state. For definition of contents of Са2 + in meat 2 methods were used. The first method is based on previous ingition of analyze produce, receiving solution of ash and chelatometry titrating in presence of Murexid. The second methodic is grounded on mineralization of organic substances, dissolution of mineralization in chlorine - hydrogen acid with following titrating of solution of complexon III in alkaline medium. It is an example of potentiometric titration on reaction of complex formation. Moisture definition was made by an arbitration method. For the aim to study of time history of physicochemical properties of sausages during storage analyze of fresh sausage and in 14 days storage of examples at the temperature of 4-6°С and a relative humidity of 85 % were carried out. According to the received results size of pH variates slightly (increases on 0.1in examples №1and №5). Moisture content in process of storage by reason of drying decreased at the average by 14 %.

  • Peter Hlaváč :
    Changes of the dark beer rheologic properties during storage37-40en [130.10 kB - PDF]EPA-02408-00003-0120

    Abstract: Results from measuring of rheologic properties of dark beer are shown in this paper. Dependencies of dynamic viscosity on rotational frequency of probe are shown. Dependencies of dynamic viscosity, kinematic viscosity and fluidity on temperature and on time of storing are described. Dependencies of dynamic viscosity on rotational frequency of probe had increasing shape. Dynamic viscosity had increased with time of storing. Dependencies of dynamic viscosity and kinematic viscosity on temperature had decreasing shape. Dynamic viscosity and kinematic viscosity had increased a bit with time of storing. Dependencies of dark beer fluidity are increasing with temperature. Fluidity of used sample had decreased a bit with time of storing. In Tab. 2 can be seen coefficients A, B, C, D of regression equations (3, 4).

  • Zuzana Hlaváčová ,
    Ákos Kertész :
    Some electrical properties of dried quinces cydonia oblonga40-44en [151.50 kB - PDF]EPA-02408-00003-0130

    Abstract: The electrical measurements are utilized at appraisal of various fruits quality. Samples of dried quince were delivered by Faculty of Agriculture of University in Novi Sad. The samples were dried in osmotic drier on the beginning and in convective drier after it. Electrical resistance, impedance and capacitance were measured by LCR meter Good Will LCR-821. Measurements had been realized at frequencies from 100 Hz to 200 kHz. Frequency dependencies of electrical properties were determined for all samples. The capacitance, resistance, impedance and relative permittivity as well decrease powerly in dependence on the frequency. The differences between values of capacitance belonged to different quinces are very small. We can deduce that the method of drying ensured the same properties of all apricot pieces.

  • M. Jůzl ,
    P. Břenek ,
    ©. Povolná ,
    ©. Nedomová :
    Physical quality of potato varieties (solanum tuberosum l.)44-47en [128.41 kB - PDF]EPA-02408-00003-0140

    Abstract: Ten potato varieties were studied for firmness of raw tubers and texture of the boiled product. Textural properties of selected varieties of potatoes were evaluated using unaxial compression test on a device Tira test 27025. Cylindrical specimens of the exact size were prepared from raw and boiled potatoes. The force needed for compression was recorded and assessed.
    In raw potatoes the varieties with the biggest hardness was variety Red Anna (201,2 N), Keřkovské rohlíčky (186,5 N) or Korela (186,2 N). The variety Jitka needed only the force of 133,5 N to be compressed.
    The most hard boiled potatoes was the varieties Rosara (12,0 N) and Ditta (11,3 N). Both of them are classed to cooking type AB. Minimal force for compression needed the variety Katka (3,8 N) which is cooking type BC.
    According to the results of the tests there is evident relation between the cooking type and hardness of boiled potatoes. It is valuable and could help us to observe some planting conditions, like physiological maturity in relation of potato quality for consumers.

  • N. Katrandzhiev ,
    G. Krivoshiev ,
    R. Chalucova :
    Non-destructive sorting of potatoes47-50en [1.12 MB - PDF]EPA-02408-00003-0150

    Abstract: The internal quality of potatoes and other vegetables and fruits is an important quality factor for both consumers and food industry. There are several diseases and defects, which have no effect to the quality of potato skin. Therefore internal defects remain invisible to human and also to ordinary camera.

  • Koleva Lyubka ,
    Staneva Donka ,
    Yordanova Ivanka ,
    Bineva Tsvetanka ,
    Vassilev Andon :

    Abstract: A pot experiment has been conducted in “Poushkarov” Institute of Soil Science during 2007 to study the effects of metal contaminated soil on Cd, Zn and Pb plant accumulation, plant performance and grain productivity of three durum wheat cultivars. The contaminated soil was taken from the vicinity of the nonferrous metal producing smelter near Plovdiv, while the control, noncontaminated soil having similar physical-chemical properties - from the experimental field of the Agricultural University of Plovdiv. Plant samples were taken and measured for heavy metal content in root, leaf, stem and grain during the vegetation period. Both chlorophyll content and leaf gas exchange parameters were determined in the flag leaf at the stage of grain filling. The grain productivity was established at harvest. The results showed that the wheat plants from all cultivars grew weaker in metal contaminated soil than the respective controls during the whole vegetation period. This corresponded to their decreased net photosynthetic rate, final shoot dry biomass accumulation as well as lower grain productivity. Grain Cd content was over the permissible limits in all durum wheat cultivars.

  • Ahmet Kücükcetin :

    Abstract: The aim of this work was to study how the incubation temperature and the storage time can affect the physicochemical characteristics, including graininess and roughness, of stirred yoghurt. Yoghurts were incubated at 37, 42 or 45°C. Physicochemical properties of stirred yoghurt were determined during storage at 4°C for 15 days. Visual roughness, number of grains, perimeter of grains, syneresis, storage modulus, and yield stress decreased, when the incubation temperature was decreased. The storage time did not affect any of the physicochemical properties of yoghurt, except for the pH. For practical applications, incubation temperature can be optimized to improve quality or modified to create fermented milk products with different physical properties.

  • T. Lõugas :

    Abstract: Sea buckthorn (Hippophae rhamnoides L., Elaeagnaceae) as an edible berry has a long history of application as a food both in Asia and in Europe. To describe the berries for different kind of purposes (transportation, processing) some chemical and physical analyses (the moisture content, dimensions and size distribution of the berries and also puncture resistance) were carried out.

  • Rositsa Mladenova :
    Advance methodology for control of chemical contaminants in food64-67en [101.79 kB - PDF]EPA-02408-00003-0210

    Abstract: In order to ensure the safety of food, it is necessary to consider all aspects of the food chain from the primary production through the harvesting and storage to the processing and sales and supply of food to the consumer. The main contemporary tendencies in fast screening of food contaminants and residues are discussed. The main steps of laboratory analysis are mentioned. Besides laboratory available methods for precise and relevant analysis, some practical approaches are presented for early detection of contaminants as immunoassay in different formats. Their advantages and disadvantages comparing to the traditional instrumental methods are outlined.

  • ©. Nedomová ,
    J. Buchar ,
    L. Severa ,
    J. Simeonovová :

    Abstract: Hens eggshell behavior at the impact by a circular rod is studied. The instrumentation of the rod enables to obtain time history of the force at the point of the bar impact. The velocity of the rod is gradually increased up to some critical value at which the eggshell failure starts. At the same time the surface displacement of the eggshell is also recorded. The numerical simulation of the egg behavior under this impact has also been performed. LS DYNA 3D finite element code has been used for the evaluation of the force and surface displacement at the points of their experimental detecting. The experimental results well agree with numerical ones. The elaborated computational procedure has been future used for the numerical simulation of the Hens eggshell behavior at the impact on a rigid plate. Qualitative features of the numerical simulation agree with results recorded using of the high speed camera.

  • Ivan N. Panchev ,
    Kostantsa I. Pavlova ,
    Мargarita Y. Кuncheva :

    Abstract: Rheological properties of glucomannan were studied, such as its intrinsic viscosity (6.90 ± 0.22) dl.g-1. The rheological profile of aqueous solutions of glucomannan was described by the power law τ = Kγn as the value 0.33≤n≤0.60 was not affected in a statistically noticeable manner by variations of concentration 0.25≤C≤2.0% or temperature 25≤T≤820C, which confirmed the pseudoplastic behaviour of glucomannan solutions as non-Newton liquids. It was shown that the structuring of the concentrated aqueous solutions of glucomannan was due to the formation of hydrogen linkages between the relevant macromolecules.

  • Ivan N. Panchev ,
    D. D. Dimitrov ,
    L. N. Genchev :
    Laser ablation of fruit and vegetables82-83en [97.67 kB - PDF]EPA-02408-00003-0270

    Abstract: This work considers the possibilities for peeling fruits and vegetables by treatment with a CO2 laser. It was found that for the fruits under study the laser ablation provided an efficient peeling of the materials while preserving the organoleptic properties, such as freshness, naturalness, and texture. As a result of the treatment, a number of aroma substances were released, as well as plant cells, which could be used in the production of edible food coatings - an alternative to emulsion produced biopolymer films. After laser treatment of citrus fruit (oranges and lemons), the fruits were peeled and pectin was extracted from the peels by means of a classical type of extraction in HCl water solution. The pectins obtained were studied for yield, degree of esterification, polyuronic content, molecular weight, gel strength and other physico-chemical prop-erties. It was found that in all samples the laser pretreatment of the materials led to an increase in the pectins yield, gel strength and purity, at an insignificant reduction of its molecular weight and degree of esterification.

  • Máris Gilingerné Pankotai ,
    Zsuzsa Varga ,
    Erzsébet Pálfi :

    Abstract: Berries (raspberry, blueberry, blackberry, black and red currant, gooseberry, etc.) are one of the popular group of fruits. They contain pigments in a big quantity. These pigments belong to the group of the anthocyanidins and are mostly flavonoids. These compounds are very important in the healthy nutrition. Our aim was to examine the berry species known on Hungary and the prepared foods from them. We wished to collect data with the examinations the fruit’s antioxidant characteristics, and to find contexts concerned with the measured antocianidin pigment content with C-vitamin content.

  • Prof. as. Dr. Klementina Puto ,
    Dr. Rexhep Shkurti :

    Abstract: Brucellosis is a contagious disease, caused by the Brucellosis type bacteria. It is also known as the Mediterranean disease. Albania has the biggest number of people being infected by it. This disease is transmitted from animals to people, causing "Malta Fever" to them.
    Before 1990, our country was pronounced not to be under the risk of brucellosis. But after 1990, the political, social and economic changes in Albania brought also the improper functioning of the vet and food hygiene structures and due to this, there was also an increase of the brucellosis infection to the animals and mostly to the people.
    According to the reporting health sources, actually it is one of the most contagious and dangerous diseases in Albania for the people in the rural and urban areas, alike. This fact is due to the distribution of the food products.
    One of the most distributed kinds of Brucellosis in our country, just like all around the world, is Brucella Melitensis.

  • O. Rabchenko ,
    T. Zubritskaja :
    Definition of physicochemical parameters of cow’s milk94-95en [90.09 kB - PDF]EPA-02408-00003-0320

    Abstract: Milk is one of the most valuable food stuff. It contains all nutrients necessary for human life. Quality of milk as uniform physicochemical system depends on characteristic of components containing in them. Therefore, any changes in content and condition of milk components should be accompanied by changes of its physicochemical properties.
    Definition of physicochemical properties of unboiled cow’s milk from various settlements of the Grodno region with aim of definitions of its quality was the task of this work.
    Indexes of acidity and density were studied in this work. Acidity of milk is determined by method of acid-base titration and potentiometry. Titratable acidity of (oT) milk depends on a ration of feeding, breed, age, individual features of animal. Rise of acidity of milk to 20-25 oT as a rule depends on deficient quantity of salts of calcium in forage. Besides, acidity of milk increased at storage at development in them of microorganisms. Deacidification of milk can be caused by its falsification, notably by dilution by water.

  • Piret Raudsepp ,
    Tiina Lõugas :
    Physical characteristics of sea buckthorn berries grown in 200795-99en [116.54 kB - PDF]EPA-02408-00003-0330

    Abstract: Sea buckthorn (Hippophae rhamnoides L.) is a native bush to Europe and Asia that produces orange to yellow berries. Its berries have a wide range of uses in medicine and also in food industry.
    Harvested sea buckthorn berries proceed to several processing operations which all emphasize knowing all the necessary data about their physical properties like size, shape, weight, moisture content and firmness.
    Size and shape showing the uniformity are important features to achieve the highest level of efficiency in processing. Moisture content refers to the juicy of the berries. Force and energy required to rupture the sea buckthorn berries depend on several factors as the strength of the skin, the firmness of the flesh, the viscosity of the juice, the turgid pressure, and the size of the fruit.

  • András S. Szabo :

    Abstract: The paper deals with some special questions of aspects of food safety and application of methods of food physics in food processing and in food quality control and assurance, as well (Figure 1). The role of food safety has developed significantly in the last decades, so today the production and processing of safe and quality food is of primary importance. Modern food production is based on principles of GAP and GMP (including GHP) and different methods and tools for quality assurance (HACCP, ISO-9000, ISO-22000, TQM).

  • Vintila Juliana :
    The management of risks in the edible oils industry106-110en [86.77 kB - PDF]EPA-02408-00003-0360

    Abstract: Risk Management System is an important part of the developing and executing of a business plan in the food industry. Effective implementation of Risk Management System promotes best practice concepts at the corporate/strategic level as well as a improving of technological operation. A proactive approach of the Risk Management System should form a core part of the decision-making process at all levels within an productive organization. The European legislation in the field of industrial risks management identify two types of risk:
    - the chronic risk (integrated control and prevention of pollution).
    - the accidental risk: fires, explosions, noise, air pollution, water, waste pollution resulting from the radioactivity.
    The objective of this paper research is to define a Risk Management System in the edible oils industry and to identify the axes of reforms to conduct at the prevention of the industrial risks.

  • Eszter Vozány ,
    Péter Benkő :

    Abstract: The magnitude and phase angle of impedance were measured with a HP 4284A LCR meter on Gala apples purchased on the local market. Two ECG electrodes (Fiab Spa) were applied on apple with skin and without skin at several places on the apple surface along the equatorial. The good electrical contact between the electrodes and apple was realized with a conducting gel. The impedance spectra were determined in frequency range from 10 Hz till 1 MHz at 1 V measuring voltage. Each measured spectrum after an open and short correction was approached by a circuit model consisting of a serial connection of impedance of apple skin and impedance of intracellular and extracellular apple flesh. The complex non-linear least squares method was applied with Mathlab program. This approaching method can allow getting the impedance of apple flesh under the skin without peeling.

  • At. Zlateva ,
    I. Yordanova ,
    D. Staneva :

    Abstract: By reason of the big radiation-hygienic significance of tritium for the individual its specific activity is determined in soils, plants (agricultural and aquatic) and water from BR"Srebarna" and surface waters from North and South Bulgaria. The determined levels of specific activity are low, due to global cycling tritium, and show the lack of local tritium contamination

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