Most important results achieved in 2011
authors from other organizations are marked by an asterisk (*)

Beran M., Toman F., Drahorád J.: Zařízení pro beztryskovou odstředivou výrobu nanovláken a mikrovláken na povrchu rotujících válců s profilovaným povrchem. [Apparatus for nozzleless centrifugal manufacture of nanofibres using rollers with profiled surface.] Utility model No. UV 22711.
This utility model is concerned with the device for the nozzleless centrifugal production of nanofibres and microfibres from polymer solutions or melts using rollers with the profiled surface. The principle consists in spray application of the spinned polymer solution or melt on the surface of a very rapidly rotating rollers or a system of rollers that may or may not be in mutual contact. The surface of this roller or rollers is profiled in various ways and the edges of these surface profiles increase the quantity of produced fibres.

Cuhra P.*, Gabrovská D., Rysová J., Hanák P., Štumr F.*, Plicka J.*, Tomková K.*, Dvorská P.*, Kubík M.*, Baršová S.*, Karšulínová L.*, Bulawová H.*, Brychta J.*, Malmheden Yman I.*, Iametti S.*, Guisantes Del Barco J. A.*, Martínez Quesada J.*, Suñen Pardo E.*, Postigo Resa I.*, Takkinen K.*, Laukkanen M. L.*, Pardo M. A.*, Baranda A.*, Martínez de Marañon I.*, Jimenez E.*, Piknová L*., Langerholc T.*, Čenčič A.*: ELISA kit for mustard protein determination – Collaborative study. [Souprava ELISA pro stanovení proteinů hořčice – kolaborativní studie.] Journal of AOAC International (2011) 94(2): 605–610.
A circular test was performed in twelve laboratories to validate the ELISA method developed for quantitative determination of mustard proteins in foods. This method is based on polyclonal rabbit antibody. In-house validation did not prove any cross reactivity to a broad range of foods. All participants obtained the kit with operational instructions, a list of samples, the samples themselves and a form for recording test results. The test included 15 food products and 2 spiked samples. The results of the circular test were analyzed using statistical tests (Cochran, Dixon and Mandel) and the analysis of variance (ANOVA). Repeatability, reproducibility, LOD and LOQ of this method were calculated.

Gabrovská D., Rysová J., Fiedlerová V., Holasová M., Laknerová I., Winterová R., Erban V., Němečková I.*: Rozšíření nabídky o nové zeleninové a ovocno-zeleninové šťávy. [Extension of the offer with new vegetable and fruit-vegetable juices.] Výživa a potraviny (2011) 66(4): 92–94.
The aim of the work was to propose new blended fruit-vegetable and vegetable juices containing less commonly used vegetables like e.g. cabbage, celeriac and parsnip, and to offer to the consumer new products interesting in taste or nutritional properties. Another possible alternative consists in the use of vegetable juices combined with sweet whey. The juices produced in the laboratory were subjected to sensory evaluation and to the determination of basic composition, the contents of total polyphenols and ascorbic acid, and antioxidant activity.

Gabrovská D., Rysová J., Laknerová I., Ouhrabková J., Průchová J., Strohalm J., Novotná P., Houška M., Kejmarová M.*, Němečková I.*, Loučková K.*: Ovocno-zeleninová šťáva. [Fruit-vegetable juice.] Utility model No. 21951.

Gabrovská D., Rysová J., Laknerová I., Ouhrabková J., Průchová J., Strohalm J., Novotná P., Houška M., Kejmarová M.*, Němečková I.*, Loučková K.*: Ovocno-zeleninová šťáva. [Fruit-vegetable juice.] Utility model No. 22035.

Gabrovská D., Rysová J., Laknerová I., Ouhrabková J., Průchová J., Strohalm J., Novotná P., Houška M., Kejmarová M.*, Němečková I.*, Loučková K.*: Tlakovaná ovocno-zeleninová šťáva. [Pressurized fruitvegetable juice.] Utility model No. 22036.
The aim of the work was to propose new blended fruit-vegetable and vegetable juices containing less commonly used vegetables like cabbage, celeriac and parsnip, and to offer to the consumer new products interesting in taste or nutritional properties. The juices produced in the laboratory were subjected to sensory evaluation and to the determination of basic composition, the contents of total polyphenols and ascorbic acid, and antioxidant activity. Subsequently they were treated with high pressure (410 MPa). This way of treatement preserved nutritionally important substances, but disintegrated cell structures of the microorganisms to the extent that they stopped growing until the end of the shelf life.

Landfeld A., Matser A.*, Strohalm J., Indrawati O.*, Van der Plancken I.*, Grauwet T.*, Hendrickx M.*, Moates G.*, Furfaro M.E.*, Waldron K.*, Betz M.*, Halama R., Houska M.: Can qualitatively similar temperature-histories be obtained in different pilot HP units? [Lze dosáhnout kvalitativně podobných
teplotních historií v různých pilotních vysokotlakých jednotkách?] Innovative Food Science and Emerging Technologie (2011) 12(3): 226–234.
An experimental protocol to harmonize the pressure and temperature-histories of model samples treated in different individual high pressure pilot units was developed. This protocol was based on the endpoint strategy. Step zero of this protocol consisted of the measurements of the pressure and temperaturehistory of the pressure transmitting medium in different chambers without the use of a container. In steps one and two of the protocol, the temperature of a sample was measured. Two types of samples were considered, a pure water sample allowing free convection (step 1) and a viscous water-based system (using a water soluble thickener) preventing free convection in the sample container (step 2). The high pressure units differed primarily in pressure build-up and pressure release times. The suggested endpoint strategy enabled the minimization of differences in temperature-histories during the pressure holding phase. Pressure and temperature histories measured in the different high pressure units and information on the inactivation kinetics of a-amylase based systems were used to compare the process impact of different pressure and temperature-histories on enzyme inactivation. The differences in temperature-histories significantly influenced the degree of enzyme inactivation; in particular the temperature-histories during the pressure build-up phase substantially contributed to differences in residual enzyme activity.

Landfeld A., Strohalm J., Halama R., Houska M.: Quasi adiabatic compression heating of selected foods. [Kvaziadiabatický kompresní ohřev vybraných potravin.] High Pressure Research (2011) 31(1): 140–147.
The quasi-adiabatic temperature increase due to compression heating during high-pressure processing was studied, using a specially designed equipment. The temperature increase was evaluated as the difference in temperature between atmospheric pressure and nominal pressure during compression. The temperature was measured using a thermocouple located in the centre of a polyoxymethylene cup, which contained the sample. Fresh meat balls, pork meat pate, and tomato purée temperature increases were measured at three initial temperature levels between 40 and 80°C. Nominal pressure was either 400 or 500 MPa. The results showed that the fat content had a positive effect on temperature increases. Empirical equations were developed to calculate the temperature increase during high pressure processing at different initial temperatures for pressures of 400 and 500 MPa. This thermal effect data can be used for numerical modelling of temperature histories of foods during high- pressure-assisted pasteurization or sterilization processes.

Landfeld A., Strohalm J., Stancl J., Houska M.: Thermal diffusivity of Swedish meatballs, pork meat pate and tomato puree during high pressure processing. [Teplotní vodivost švédských masových kuliček, paštiky z vepřového masa a rajčatového pyré během ošetření vysokým tlakem.] High Pressure Research (2011) 31( 2): 358–366.
This study is directed at the effects of high pressure on the thermal diffusivity of selected foods – a fresh meat formulation for Swedish meatballs, pork meat pate and tomato puree. Preheated food samples were placed in a copper cell and tested at nominal pressures of 400 and 500 MPa in a high pressure chamber. Thermal diffusivity was estimated from the recorded time course of temperatures (at the axis of the copper cell, at the wall of the cell, and 7.5 mm from the cell wall) during the high pressure holding time. The measured time-temperature profiles were compared with predictions using the finite-element model to solve the problem of uneven heat conduction in an infinite, solid, linear cylinder using the linear temperature dependence of apparent thermal conductivity. Optimal parameters of the linear temperature dependence of apparent thermal conductivity were evaluated by comparing measured temperatures and temperatures calculated from the model. To minimize differences between measured and calculated temperatures at the axis of the sample the Marquardt–Levenberg optimization method was used. The thermal diffusivity values of all food samples were linearly correlated with temperature for two levels of pressure. Thermal diffusivity values increased with increased pressure and temperature.

Mašková E., Paulíčková I., Rysová J., Gabrovská D.: Evidence for Wheat, Rye, and Barley Presence in Gluten Free Foods by PCR Method – Comparison with Elisa Method. [Důkaz přítomnosti pšenice, žita a ječmene v bezlepkových potravinách metodou PCR – porovnání s metodou Elisa.] Czech J. Food Sci. (2011) 29(1): 45–50.
A method to prove the presence of wheat, rye, and barley in gluten free foods, based on the polymerase chain reaction (PCR), was validated. DNA was isolated from foods by chemotropic solid phase extraction. The PCR method applied was focused on the introne of the chloroplast gene trnL and utilised primers WBR11 and WBR13. Electrophoresed wheat and rye DNAs were characterised by a 201 bp fragment, barley DNA by a 196 bp fragment. The validated PCR method was applied to the selection of 18 gluten free foods, previously found by the ELISA method to contain 1 mg or more of gliadin per 100 g food. The presence of wheat was confirmed by the PCR method in all foods analysed. The comparison with the results obtained by the ELISA method reliably verified the detection limit of the PCR method, i.e., 0.02 % wheat.

Novotná P., Šetinová I.*, Heroldová M.*, Kmínková M., Průchová J., Strohalm J., Fiedlerová V., Winterová R., Kučera P., Houška M.: Deallergisation trials of pure celery juice and apple celery juice mixture by oxidation. [Testy dealergizace čisté celerové šťávy a jablečno-celerové šťávy oxidací.] Czech J. Food Sci. (2011) 29(2): 190–200.
The aim of the work was the verification of the possibility of removing or reducing the content of the Api g1 allergen in celeriac juice by oxidation, utilising its natural polyphenol oxidase (PPO) content. The possible relationship between the enzymatic browning of celeriac juice and the reactivity of the Api g1 allergen contained therein was assessed. Pressed celeriac juice was stirred and, at given times, sampled for colour measurement and allergenicity determination by the Western Blot (WB) method. Oxidation failed to eliminate the allergenicity of pure celeriac juice. Our earlier finding that apple juice blended with carrot juice removes allergen from carrot was therefore employed. Apple-celeriac juice blends were made in ratios 3:1, 5:1, and 7:1 and their colour was observed during oxidation. The 5:1 ratio was chosen as the most acceptable in terms of sensory properties, and its allergenicity was observed using the WB method, basophil activation test, and skin prick testing. The WB test showed that oxidation induced by stirring for 120 min reduced the allergenicity of the blend. The basophil activation test showed no reduction in the allergic response to the oxidised juice blend. The skin test showed that the oxidised juice blend stirred for 120 min exhibited a significantly lower reaction than the blend stirred for 60 min or celeriac and apple juice stabilised with ascorbic acid.

Somkuti J.*, Houska M., Smeller L.*: Pressure and temperature stability of the main apple allergen Mal d1. [Tlaková a teplotní stabilita hlavního jablečného alergenu Mal d1.] European Biophysics Journal (2011) 40(2): 143–151.
High-pressure Fourier-transform infrared (FTIR) spectroscopy was used to determine the pressure and temperature stability of the main apple allergen Mal d1. This study was triggered by contradictory results in the literature regarding the success of pressure treatment in the destruction of the allergen. The protein unfolded at 55°C when heated at normal atmospheric pressure. Pressure stability and the effect of environmental factors on the stability of the allergen in the apple were also studied. The pressure unfolding was measured under different pD conditions, and the effect of sugar mixture similar to that of the apple and the effect of ionic strength were also studied. In all cases the allergen unfolded with a transition midpoint in the range of 150–250 MPa. Unfolding was irreversible and was followed by the aggregation of the unfolded protein. Lowering the pD destabilized the protein, while addition of sugar mixture and of KCl had a stabilizing effect.

Vavreinová S., Ouhrabková J., Rysová J., Fiedlerová V., Holasová M., Laknerová I., Winterová R., Prokeš J.*, Hartman I.*: Nutriční hodnocení sladů z obilovin a pseudoobilovin. [Nutritional assessment of malts from cereals and pseudocereals.] Úroda (2011) 12, vědecká příloha, 133–136.
Nutritional analyses were performed of seven kinds of barley malts (diastatic, Pilsen, Munich, caramel, dark caramel, colouring), rye malt, three kinds of wheat malts (wheat, diastatic, caramel) and three kinds of buckwheat malts (diastatic, kilned at 105°C and caramel). Antioxidant activities of malts by the DPPH+ and FRAP methods and total polyphenol contents were determined. The malts analyzed will be used for the enhancement of nutritional, sensory and textural properties of breads and other baked goods in collaboration with a baking factory.

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