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Rytel E.,Wroclaw University of Environmental and Life Sciences
Food Control | Year: 2012

The aim of this experiment was the determination of glycoalkaloid and nitrate content in potatoes during stages of processing into dry potato dice.Samples obtained from the tubers of three potato varieties were used: a very early Denar variety of Polish origin; Innovator, an early Dutch variety; and a Polish medium early Pasat variety. There were sampled three times from the factory store in 2009 and 2010. The potatoes were diced in laboratory conditions, by first peeling with a carborundum peeler, dicing into 10 × 10 × 10 mm pieces and rinsing with water at a temperature of 20 °C. In the next stages, the diced potatoes were blanched in water at a temperature of 75 °C for 5 min then dried in a laboratory drier for 1 h at 120 °C. After 1 h of drying, the temperature was lowered to 55-60 °C in order to obtain a defined final moisture content of 8-11%.In the raw material, intermediates and finished products, the concentrations of glycoalkaloids (α-chaconine and α-solanine) were determined using an HPLC method, and nitrates were determined colorimetrically using an RQflex analyser.It was found that the processes used in dried potato dice production significantly decreased concentrations of glycoalkaloids (α-chaconine and α-solanine) in intermediate and finished products when compared to raw material. The highest decrease in the quantity of glycoalkaloids occurred during peeling (33%) and after blanching (17%) of peeled potato. Nitrate content fell the most after cutting and rinsing with water (13%), and after blanching (23%). On average, dry potato dice contained 44% of the initial quantity of glycoalkaloids and 40% nitrate content in the final dried product. © 2011 Elsevier Ltd. Source


Grabarczyk M.,Wroclaw University of Environmental and Life Sciences
Molecules | Year: 2012

Bicyclic chloro-, bromo- and iodo-γ-lactones with dimethylcyclohexane rings were used as substrates for bioconversion by several fungal strains (Fusarium, Botrytis and Beauveria). Most of the selected microorganisms transformed these lactones by hydrolytic dehalogenation into the new compound cis-2-hydroxy-4,6-dimethyl-9-oxabicyclo[4.3.0]- nonan-8-one, mainly the (-)-isomer. When iodo-γ-lactone was used as the substrate, two products were observed: a hydroxy-γ-lactone and an unsaturated lactone. The structures of all substrates and products were established on the basis of their spectral data. The mechanism of dehalogenation of three halolactones was also studied. Source


Kita A.,Wroclaw University of Environmental and Life Sciences
European Journal of Lipid Science and Technology | Year: 2014

Fat uptake and the characteristic crispy and crunchy texture are the main quality parameters of fried potato products such as the most popular French fries and potato crisps. They are formed during the frying process and depend on different factors, among which frying oil properties and frying conditions were taken under investigation. Quality of frying oils as well as fatty acid composition and degree of degradation affect fat uptake and texture of fried potato products. Technological parameters such as frying temperature and frying conditions were also considered. Practical applications: Factors affecting fat uptake and texture of fried potato products such as French fries and potato crisps are discussed. The kind and quality of frying medium as well as frying parameters (temperature, using vacuum) influence fat uptake and texture of fried products. Texture of fried potato products is correlated with fat content and composition of frying medium. Higher frying temperature decreases hardness of French fries and potato crisps, which exhibit more crispy and delicate texture in comparison with products fried at lower temperatures. Fat uptake and characteristic crispy and crunchy texture are the main quality parameters of fried potato products. They are formed during frying process, but depend on different factors, among which frying oil properties as well as frying conditions were taken under investigation. Quality of frying oils as well as fatty acid composition and degree of degradation affected fat uptake and texture of fried potato products. Technological parameters such as frying temperature as well as frying conditions also were taken under consideration. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Rohm W.,Wroclaw University of Environmental and Life Sciences
Atmospheric Research | Year: 2012

The GNSS signal passing through the layers of the atmosphere, including troposphere is subjected to many effects. One of the effect is a change of signal phase propagation speed due to the change of density. The large fluctuation of density is due to water vapor content - the most important greenhouse gas. The ground GNSS tomography is a tool to obtain the wet refractivity of the discrete model above the network of receivers. The wet refractivity could be converted into water vapor partial pressure, using the additional temperature information. This paper presents rigorous approach to obtain uncertainties of the final product - water vapor partial pressure in the voxel. All factors influencing the final uncertainty has been taken into account, mainly uncertainty of: Zenith Troposphere Delay, pressure, antenna phase center height, satellite elevation angle, mapping function, tomography solution and temperature. The analyzed error budget shows, great influence of cofactor matrix topology on tomography solution uncertainty. It is also shown that ground GNSS tomography is feasible to obtain water vapor partial pressure in the troposphere up to 0.5. hPa so in average 6. km above the ground. © 2012 Elsevier B.V. Source


Figiel A.,Wroclaw University of Environmental and Life Sciences
Journal of Food Engineering | Year: 2010

Beetroot cubes were dehydrated by convective drying in hot air at 60 °C and by the combination of convective pre-drying (CPD) until moisture content 1.6, 0.6 or 0.27 kg/kg db and vacuum-microwave finish drying (VMFD) at 240, 360 or 480 W. The control samples were obtained by freeze-drying (FD). The drying kinetics of beetroot cubes was described with an exponential function. VMFD significantly reduced the total time of drying and decreased drying shrinkage in comparison with convective method. A critical moisture content divided the temperature profile of samples during VMFD into increasing and falling periods. At the falling temperature period a significant increase in the colour parameters L*, a* and b* was found. VM treated samples as well as FD ones exhibited lower compressive strength, better rehydration potential and higher antioxidant activity than those dehydrated in convection. Increasing the microwave wattage and decreasing the time of CPD improved the quality of beetroot cubes dried by the combined method. © 2010 Elsevier Ltd. All rights reserved. Source

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