Abstract: In the paper information is given about some special questions of aspects of food safety and application of principles of food physics in the agro-food sector. The role of food safety has been developed significantly in the last 2-3 decades. The food production and processing of quality food and safe food are of primary importance. Food production is based on the principles of GAP, GMP and GHP, and different methods and tools (e.g. HACCP, ISO-9000-2000, TQM, ISO-22000) for quality control, safety and quality assurance are in use. Today the agricultural production and the industrial food processing are focused dominantly on the quality, and one of the basic requirements in the agro-food sector is the safety.
There are different methods and techniques to produce safe food. The up-to-date food technologies and quality measurements involve the application of different physical methods – high pressure, pulsing electrical field, nondestructive techniques (e.g. NMR, NIR-NIT) for chemical composition determination, radiation techniques etc. – as well. Using ionizing and non-ionizing radiation technologies it is possible to fulfil e.g. the following expectations: decrease of the microbial contamination, increase of the storability, improve of the sensory properties.
Abstract: Pectin films were measured by Stable Micro Systems® penetrometer, with relaxation method. Citrus pectins from CP Kelco® were varied in charge distribution and degree of esterification. There was some amidated pectin from PIC Co as well. A controlled hydration by polyethilenglicol (PEG) 20000 solution, with and without different salts and concentrations was taken. The hydration causes swelling. The equilibrium swelling of the films (after 24 hours hydration) was investigated. The force relaxation at constant deformation, achieved by slowly stretching till a small force and after that the deformation were stored for 30 second and force decreasing were measured. The curves were analysed by two rheological models – Maxwell model and Zener model, with a small modification. Results say that the Zener model shows better fitting on relaxation curves, and give some dependences for rheological properties on pectin types and concentrations.
Abstract: The paper deals with the physical properties of food materials and with study of physical processes running in these materials during the thermal food processing technology. Characterization of food materials is presented, processes running in the materials and possible methods of study are introduced.
Abstract: The recognition of radionuclides from characteristic gamma rays is the most widely used method for activity concentration determination. It is shown that by means of high resolution low background gamma spectroscopy most of radionuclides in the food can be determined. By means of passive and active shielding of the detectors detection limits far below 1 Bq/kg can be achieved. Some recent results on radionuclide content of food on the market will be present. The role of TENORM sources in food contamination will be discussed.
Abstract: The measurements were done on the wheat grains mixture removed from the purchase corporation in Rybany and oil seeds from Hontianske Nemce during storage. Moisture content was determined according to standards. Electrical properties were measured at various frequencies after various time of storage in silo. The capacitance and relative permittivity decrease with frequency powerly. Results showed that specific changes occurred in quality of all wheat grains components – proteinic profile and saccharide complex. Relative permittivity decreases with storage time according to quadratic function. Similarly for the crude protein and starch content and that is why a correlation exists between changes in relative permittivity and in crude protein and starch content during storage. A correlation between the changes in relative permittivity and wet gluten content and crude fibrous material respectively do not exist. It was impossible to create the time dependencies for oil-seeds because of short storage time.
Abstract: The infection of wheat by the field fungus influences its yields, the total quality and the hygienic accurance. At the mill, the cleaning process is not sufficiently effective, so the well developed, but infected kernels are present in the mass in front of the first grinder.
The results from the investigations have shown that the fungus of the species Fusarium are the most present contaminants, and the most present among them was F. oxysporum. Besides the fuzariums the fungus of the genus Altenaria were also present. At the most contaminated kernels their matabolits were isolated. The influence of the of the micotoxins Zearalenon and Ohratoxin A on the wheat quality was determined by the changes of the technologycal quality and the hygienic accurance.
Abstract: Physical characteristics of sea buckthorn berries in nine different varieties in two different years (1998 and 2005) grown in Estonia are described.
The moisture content, dimensions and size distribution of the berries and also puncture resistance are determined. The moisture content of the berries is in the range of 80-87%. The geometric mean diameter of the berries varies from 8.64 to 12.57 mm. The lowest value of puncture resistance is 199 g and the highest is 304 g. The freezing has some influence on puncture resistance.
Abstract: The properties of supersaturated glucose, fructose and sucrose solutions were characterized and the changes appearing in their crystallization investigated. It was found that aw, hardness and stickiness of glucose and fructose solutions were identical. The glucose and sucrose solutions crystallized with one week and one day, respectively. The fructose solution didn’t crystallize. During crystallization the water activity of the sugar solutions increased.
Abstract: The aim of the paper was to analyze the results of food radioactivity control in Nis in five year period after the war in 1999 and to identify possible health hazards. The routine food safety control were done in Public Health Institute, Nis from 2000-2004. Samples of food were analyzed in certified institutions of Serbia for radioactivity control by using standard procedure. 676 food samples were controlled (196 domestic and 480 imported food). The radioactivity of analyzed food samples was at the normal environmental levels and we do not anticipate health consequences.
Abstract: In the paper information is given about the investigations of homemade dehydration of different domestic (apple, plum, sour cherry), subtropical and tropical (lemon, orange, kiwi, banana, pineapple) fruits, preserved by home-made dehydration technique. For dehydration FD-510 type electric heater was used. The content of water in the dehydrated samples was determined in drying owen. The sensory parameters, the rheological properties, the texture and also the storability depend significantly on the water content (and water activity) of the dried fruits.
Abstract: Ketchup is a typical food product, which possesses a thixotropic behaviour. The destroying and the recovery of its structure were monitored by rotational viscometry HAAKE VT 550. The Moore model, which describes the thixotropic behaviour by structural parameter λ was chosen for fitting the basic rheological curve ( τ = τ(γ& ), where τ is the shear stress and γ& is the shear rate) and the stress-time dependences at different shear rates. As a result the relaxation times at different shear rates were calculated. It was shown as well, that the ketchup possesses a spectrum of relaxation times, expresses as stretched exponent parameter β. The changes in thixotropic behaviour during storage were also monitored.
Abstract: The paper deals with an interesting application of microwave technique: food technology. The experiment uses glutinous rice flour as major raw material, corn protein, salt and water as additional material, using palm oil as surface coating of base. The optional technical conditions are glutinous rice 50g, salt 2.4g, corn protein 5g, water content 50%, palm oil 1.5% (accounting for base weight). The microwave oven’s power is 500W and heating duration 2 minutes. “Microwave instant noodle” is very fresh and mysterious to most consumers. The damage of the nutritive elements in noodle by microwave dehydration is much less than that of oil-fried product. So it is possible to produce many series of products that contain different raw materials and different compositions