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- Author or Editor: P. Stefanovits x
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On the basis of the samples studied, which were gathered over the past year, we were able to summarize the characteristics of red clays in Northern Hungary. From the large selection of samples we chose 16 representative soil profiles for our assessment. In order to characterize red clays we used data on mechanical composition, cation exchange capacity and adsorption capacity as well as the mineral composition identified by X-ray diffraction and thermoanalytical studies. Following observations and conclusions drawn from our study we were able to identify the categories of red clay in Northern Hungary: 1. Red clay of the Hegyalja region (Tokaj foothills); 2. Red soils of the Cserhát and Szalonna Hills; 3. Red clays of the Aggtelek karst, the Torna Hills and the Bódva Valley; 4. Red soils of the Bükk mountain range. 5. Red clays of the Northern periphery of the Great Hungarian Plain. The following conclusions can be drawn from the studies on the water permeability of the soils: Water permeability is correlated with the pore space and the ratio of coarse pores. The bigger the total pore space and the ratio of coarse pores, the better the water permeability of the soil. If the clay content is higher the water permeability is generally lower. In soils that contain montmorillonite the speed of water permeability is lower than in soils containing kaolinite. Within the porous system of bauxitic red clays containing kaolinite the volume of medium size and coarse pores increases, resulting in better water permeability. In the upper layers of soils covered with vegetation water permeability is much better. The high amount of roots and root residues provides better soil structure and porosity, thus improving water permeability.
Vitamins form a heterogeneous chemical group having different stability. In foodstuffs some of them might be bound to matrix components. In the case of vitamin supplemented food products, since the vitamins are not strongly embedded in the matrix a general extraction method could be fit for purpose. The aim of this study was the simultaneous determination of the most common water-soluble vitamins, i.e. ascorbic acid (C), riboflavin (B 2 ), niacin (B 3 ), pyridoxine (B 6 ), folic acid (B 9 ) in enriched food products. Sample preparation based on the European Standard (CEN, 2003) was optimised for further LC-MS compatible chromatography. The separation of the vitamins was achieved by reversed-phase liquid chromatography. Detection was carried out with a photodiode array detector at four different wavelengths. The chromatographic method and the sample preparation were successfully applied for vitamin-enriched cereal, instant cacao powder and fruit juice samples.
Different osmotic agents (OA), such as potassium acetate (CH3COOK), potassium carbonate (K2CO3) and ammonium nitrate (NH4NO3), have been examined as alternatives to the traditionally used calcium chloride (CaCl2) for osmotic distillation concentrating of clarified and pre-concentrated sour cherry (Prunus cerasus L.) juice. Comparison of the process performances based on the permeate fluxes has been carried out. Regarding the permeate flux results, simplified estimation of the overall mass transfer coefficient of the most effective osmotic agent and the reference (CaCl2) solution has been also performed. Furthermore, analytical methods such as total antioxidant activity (TAA) and total polyphenolic content (TPC) using spectrophotometric assays have been also carried out to evaluate the effect of the osmotic distillation on the valuable compounds content of concentrated sour cherry juice. CH3COOK was found to be the most effective, resulted more than 25% higher permeate flux during the sour cherry juice concentration. K2CO3 and NH4NO3 were less effective. The simplified mass transfer estimation showed that the CH3COOK is more effective only at near saturated concentrations compared to the CaCl2. Regarding the TAA and TPC contents, a significant loss was found in case of all OAs during the concentration procedures.
