No. 30 (2008)
Experiment of quality properties of dehydrated fruits7-15Views:93
The lyophilization is the joint application of freezing and drying. It is an up-to-date conserving procedure, the point of which is that the humidity existing in the frozen humid material is transferred from the solid state directly into the gaseous state at a temperature below 0 oC under vacuum. Out of the procedures applied nowadays, this is the most tolerant drying process.
With regard to the high investment and operational costs, freeze drying is applied only for valuable, heat-sensitive materials when the technological aim is to preserve such properties as aroma, taste and colour as well as such components as proteins and vitamins. This procedure is suitable for drying and conserving certain foodstuffs, stimulants, organic chemicals, medicines and similar sensitive and valuable materials.
In our institute, we have been conducting freeze drying experiments with regional fruits and vegetables since the year 2005. During the first phase, we examined the heat- and material transfer as well as the abstraction of humidity, while during the second phase we analysed the rehydration ability and nutrient content of the freeze-dried materials as compared to those dried with the method of convection. Moreover we have conducted penetration measurements with a portable hardness tester.
To sum up the results gained so far, we can state that the quality of the lyophilized materials is better than those dried in the traditional way. It originates partly in the fact that the temperature and pressure applied for the freeze drying are smaller and the drying period is far longer than for the convection drying.
In contrast to convection-dried materials, freeze dried materials set in close to their original water-content, keep their original shape and size after being rehydrated. The reason of it the porous, spongy structure (flexible cell wall) of the lyophilized products which is able to take up moisture quickly. In addition, the lyophilized products can be rehydrated faster than those dried in the traditional way.
Regarding the results of the chemical analyses, the following conclusion can be drawn: the vacuum freeze drying results a small decrease of nutrient content and nutritive value for the lyophilized products.
The results of the hardness tests support the statement that the majority of agricultural materials cannot be considered as an ideal flexible body, because during the experiment the flexibility coefficient changed when going from the surface of the material inwards. In addition, the penetration tests also confirm that the surface of the convection-dried vegetables is at least 1.5-3 times harder than that of the freeze-dried products. The reason of it that it takes place during the drying denaturation processes.
The article summarizes the results of our research work listed above, in accordance with our experiments conducted by using the characteristic fruits (apple, plum) of the Nyírség Region.
Supplementary botanical examinations for modelling the grass production of the great pasture of Hajdúbagos17-21Views:55
Our botanical survey at the great pasture of Hajdúbagos is a part of a broad research that aims to predict the production of the grass at the given area. As the mentioned pasture is a nature conservation area, the usage of artificial fertilizers or other classic grassland management methods in its handling are prohibited. Thus grazing is an important tool for the management of this area, however the not suitably regulated grazing order and the poorly calculated carrying capacity cause serious problems at some parts of the pasture. The prediction of the grass yield is essential to
avoid both over- and both under-grazing and for determining the optimal number of the grazing animal stock and the grazing method, thus the most suitable management strategy.
The potential grass yield is easily calculable with a computer model that will be established as a basis for determining the grass production. For the sake of getting an accurate view of the plant associations of the pasture, we created examination quadrates and determined all plant species found in the quadrates. After plant determination, we compiled a coenological table in which we marked besides the scientific name and families, the life forms of each species that refer to the structure, morphology and thus the adaptability of plants to their environment. We determined the
TWR, so the thermoclimate, water and soil reaction values, the nature conservation values, as well as the covering values of each plant species (DB), and the total coverage of the examination quadrates (B%).
According to the covering values, grasses proved to be characteristic plants at the examined pasture, thus we need to consider them influential in calculating the animal carrying capacity and with the rest of the information, we need to supply the model.
The life forms and TWR indicators, all together with the nature conservation values provide further important data to the development of the management suggestion of the protected pasture. By examining these values to different parts of the area, we could get an exact view on the measure of the degradation effects. This promotes the determination of grazing methods and the forming of the boundaries of certain pasture sections, to avoid those harmful anthropogenic effects that seriously endanger this extensive sandy pasture.
Effect of crop residues on soil aggregate stability23-32Views:89
Soil structure may be improved by adding readily decomposable organic matter. The extent of amelioration depends on the chemical build-up and decomposability of the crop residues. Three different kinds of organic matters were investigated: (1) maize stem, (2) wheat straw, and (3) maize stem
& wheat straw. Comparing the aggregate stabilizing effects of the differently decomposable organic matters to each other, the expected maize stem & wheat straw (mw) > maize stem (m) > wheat straw (w) order was proved.
Product orientated sewage sludge composting technologies in the practice of AKSD Ltd.33-36Views:98
In recent years the regulations of the EU unambiguously determine that the biodegradable wastes should be used for biogas production or composting. The direct use of sewage sludge in agriculture is limited by its hazardous microelement content, but it can be used effectively in composting. The limitation parameters can be extinguished with correct compost-mixture and technology variants. The exact determination of the technologies and mixtures result a stable, constant quality product. The compost, as a classified product, is friable structured. The end-product is a
homogeneous mould with good water capacity, does not contain any weed seeds and pathogenic organisms. The compost does not have a acidify effect on the soil. It is an effective fertilizer thanks to its macro and microelement content.
Phylogenetic studies of Phoma species by maximum likelihood analysis37-46Views:100
The cosmopolitan Phoma genus contains mainly phytopathogenic, opportunistic parasite, and saprophyte fungal species. Up to now the characterization of Phoma species and other taxa of Phoma has so far been determined on the basis of morphology on standardized media, and gene sequence analysis was only used as a confirmative or distinctive complement.
In this study we have tried to study phylogenetic relationships by maximum likelihood method in the Phoma genus. We employed a part of the gene responsible for the synthesis of translation elongation factor 1 subunit alpha protein (tef1) containing both introns and exons, a part of the gene responsible for synthesis of tubulin protein and ITS region containing the internal transcribed spacer regions 1 and 2 and the 5.8S rDNA as potential genetic markers to infer phylogenetic relationships among different Phoma taxa. Twenty-four isolates of eleven different Phoma species were firstly characterised by morphologically, and then their tef1, tubulin and ITS sequences were sequenced and analysed by maximum likelihood method carried out by PAUP*4.0b program. According to constructed phylogenetic trees, the different Phoma taxons are well separated. However these trees do not support the traditional Phoma sections based on morphological characterization.
The maximum likelihood analyses of all three sequences confirmed that the Phyllosticta sojicola species is clustered with the Phoma exigua var. exigua group and the Phoma sojicola is grouped with Phoma pinodella group. The experienced molecular evidences initiate the demand of reclassification of formerly mentioned soybean pathogens.
Tools of promoting „energy-crops”47-52Views:62
The utilisation of renewable energy sources have come to front with the decreasing fossil fuel stocks, the unsolved problems and fears of nuclear energy and so the cumulating energy dependence. In Hungary the potential of biomass is the largest in renewable energy sources.
During our examinations, we analysed the promotion of producing energy crops in Szabolcs-Szatmár-Bereg county. With the examination of the territories involved in energy crop subsidies it can be stated that the energy crop subsidy had its promoting role only on those areas where because of the bad soil conditions the energy crop producing is more profitable than other alternative (non energy) crops.
The expected growth rate of energy plantations will be low, according to the low rate of subsidy intensity (40-60%). The uncertainty of direct area payments decreases the calculability that cuts back the favour of investment in short rotation forestry planting.
Sight-specific development of the tools for the measurement of CO2-emission of the soil53-58Views:74
Soil is the main source and at the same time the potential sink of greenhouse gases (e.g. CO2, CH4). Measurements were carried out in the experimental sites (soil tillage experiments and an extensive pasture) of the Karcag Research Institute of University of Debrecen, Centre for Agricultural Sciences to determine the CO2-emission of the soil. The in situ CO2-emission of soil was measured by means of an ANAGAS 98 infrared gas analyser in plastic (PVC) chambers, but this previously applied method (cylinders) was not suitable for the soil surface covered with grass,
hence a new instrument was needed to be invented. In order to measure CO2-emission on a larger area without deep disturbance of the soil, a special metal frame was created with a matching bowl. The most problematic part was the spatial delimitation of the measurement area as the surface of the soil can be very various and proper isolation is a must. We consider the frame+bowl method we developed suitable for measuring CO2-emission of pastures as well as other crop-fields.
Pre-treatment of wastes containing keratin in industrial conditions59-64Views:95
The aim of the research was a development of a featherdegradation technology in industrial circumstances. During the experiments we determined the parameters of the critical environmental and technological limitation factors. Because of the high keratin-content the degradation (and composting) of the feather is difficult. With the developed technology huge mass of feather can be used fast and easily in biogas production and in the adjustment of the optimal element ratio of biomass. The industrial experiments were implemented in a 6m3 heatable double-walled
tank with stirring-shovels and aeration-system. The degradation process was followed with extinction measurements.
According to the experiments that were done the best results were given at the case which was heat-treated at 70°C, was injected with 1% bacteria concentration, and where 1:3 feather:water ratio was set if we consider the effectiveness of degradation and the hydraulical retention time.
Additional information for the interpretation of the practice of rural development in the light of the corporate relations of the Agricultural Centre, University of Debrecen in the North-Great Plain Region65-69Views:57
In the spirit of the Lisbon strategy, the European Union has set out the primary aims of innovation development and competitiveness. A potential method to reach these aims is to enhance the relation between science and practice and to apply scientific results. This is the case at the Agricultural Centre of the University of Debrecen as well, since the tighter and looser cooperations of the institution provide a scientific structure, which is now a significant prerequisite for Hungarian agro-innovation, primarily for rural development processes in the North Great Plain Region. The present study, based mostly on empirical findings, strives to analyze the field of activities in relation to rural development performed by the Agricultural Centre, University of Debrecen.
Applicability of hyperspectral technology for in situ phytoremediation71-78Views:80
The characterization of heavy metal polluted abandoned mining sites is a complicated assignment due to the variable spatial distribution of the pollutants, therefore complex integrated method is required in order to assess precisely the amount and the distribution of the contaminants. The examined area is flotation sludge reservoir of abandoned Pb-Zn mining site with serious heavy metal contamination. located in Gyöngyösoroszi, Northern Hungary.
The hyperspectral image of the flotation sludge is obtained by using a Digital Airborne Imaging Spectrometer DAIS 7915, in the frame of DLR HySens first Hungarian hyperspectral flight campaign (21/08/2002). Parallel to the flight campaign heavy metal content of soil samples were examined from the area of the flotation sludge. The analysis of hyperspectral data was verified by the examination of mine tailing samples by FPXRF (Field Portable X-ray Fluorescence spectrometry) (NITON XL-703).
Determinations of heavy metal containing minerals are based on the spectral profiles of the pixels of the area with using USGIS standard spectral profiles of the examined materials (galena, pyrite, sphalerite, goethite and jarosit).
Applying the Spectral Angle Mapper with BandMax classification the distribution of minerals (galena, pyrite, sphalerite, goethite, jarosit) in the area was defined. The mineral formation occurs especially at the levees and the barren places of the Szárazvölgyi flotation sludge reservoir. Based on the statistic results of the samples, principal component analysis and correlation coefficient between the different metal content of the samples were calculated. The highest correlations were found between Pb-Zn, Fe-Zn and between Fe-Pb. This prove the results of the principal component analysis, where usually Pb, Zn, Fe introduce the main component.
Canopy analysis was also carried out with the hyperspectal image in order to classify the differences between vegetation types at the Szárazvölgy flotation sludge reservoir and analyse the applicability of it. Supervised classification methods were used to distinguish 8 vegetation types based on the spectral properties of the area. The results of the classifications were compared to a ground truth image, based on ortophoto, topographic map, and GPS based field data collection. According to results of the comparison, the paralellpiped classification method is proved to be appropriate method based on the overall accuracy of canopy classification, which was 54% due to heterogeneity of the vegetation.
The results of hyperspectral data and FPXRF analysis suggest that Pb, Zn and Fe containing minerals have similar spatial distribution in the examined and barren area.
Based on this study hyperspectral remote sensing is likely to be an effective tool for the characterization and modeling the distribution of Pb, Zn and Fe containing minerals at the examined heavy metal polluted sites. Further more, based on the vegetation analysis plant species for phytoremediation can be defined.
Farms in the system of European supportpolicy79-83Views:65
Common Agricultural Policy (CAP) has been having a great past, it is over numerous direction and structure changes in the last half century. After the Treaty of Rome, the harmonization of he agricultural structure and the production of Member States has been launched, during which the economic changes in the world and in Europe were continuously being kept track of. By using common experience, they strived to develop an agricultural sector that supplies the Member States of the Community with food, while the competitiveness and living circumstances of family farms are being improved. The general directions outlined in Stresa in 1958 were significantly redrawn owing to the transformed market conditions and EU accessions. The subsidization of family farms and the improvement of their profitability are having a stressed importance nowadays, too. Our country, as the fully qualified member of the European Union tries to meet its obligations undertaken in the accession treaty and therefore to develop an agricultural sector carrying out diversified agricultural production with a healthy age structure. The aim of the study is to specifically overview the issue of common agricultural policy by stressing the main development points and to introduce the Hungarian conditions of family farms. Besides, there will be an evaluation of the research works examining the income conditions of family farms in the North Great Plain region.
The effect of nickel-contamination, nitrogen-supply and liming on the chemical composition of perennial ryegrass (Lolium perenne L.)85-92Views:87
Plant-production is determined by many production-factors. Each of these factors became subject of research-works through the years, still we state, that studying their interaction is even more important. For studying these interactions we set up a potexperiment, within that the direct effect and the interactions of four factors was inspected: soil, nitrogen-supply, nickel-loading and liming. Experiments were carried out on two soil types with extremely different characters: one was a chernozem soil with good fertility and buffering capacity, the other was a shifting sand soil with low humus-content and buffering capacity. Nitrogensupply and liming was added on two levels, while nickel on three within 12 combinations on each soil types. Plant production was cut two times within the vegetation period. The amount of production and dry matter was weighted, fractured and their element-content was measured by an ICP-detector.
Ca-content on the shifting sand soil was determined by all three factors, however the interaction between nickel-loading and liming was also significant. Nitrogen and liming increased Cauptake, that is due to appropriate nutrient-supply and improvement of a better pH-value. On the chernozem soil nitrogen and CaCO3 also increased the Ca-content. This is caused by a better nutrient supply and a higher amount of available Ca-ions.
On the shifting sand soil nickel content was increasing parallel to higher nitrogen-dosages. In presence of higher nickelamount the nickel-content of plants was also increasing, still according to liming, this increment was different. On the chernozem soil nitrogen a nickel increased Ni-uptake. However, liming also had a positive effect on Ni-content, that can be explained by the high amount on colloids in the soil, the adsorption of Ni-ions on them and in presence of liming material the replacement of Ca-and Ni-ions.
The potassium-content on the shifting sand soil was different in each liming-combination. In combinations without nickel the potassium-content of limed and not limed combinations was on the same level. In not limed combinations by adding nickel potassiumcontent was increasing, while in limed combinations no change was observed. On the chernozem soil by adding liming material the amount of uptaken potassium was decreasing, that is due to the antagonism between Ca- and K-ions.
Statistical comparison of soil analysing results of chernozem soils93-99Views:109
The soil fertility was degraded as a result of unreasonable tillage, therefore the application of site-specific nutrient replacement is necessary. It is essential for the application of precision fertilization to know the location, extension, soil properties and nutrient-supply of the different soil types of
We collected soil samples from 580 hectares of land in 2006. Soil samples were collected from every 5 ha in 30 and 60 cm depths during Spring from 20.05.2006 to 12.06.2006 and again in Autumn from 09.19.2006 to 02.10.2006. Soil samples were analysed at the Department of Agricultural Chemistry and Soil Science of DE-ATC.
The two examined soils are slightly calcareous, weakly saline, poor in zinc. The calcareous chernozem soil is slightly acid, the content of humus, nitrogen, phosphorus and potassium is medium in this soil. The meadow chernozem soil is slightly alkaline, and properly supplied with humus and potassium, and middling supplied with nitrogen and phosphorus. The meadow chernozem soil is more heterogenous in soil plasticity, lime, saline, nitrogen phosphorus and potassium content and less heterogenous in pH and zinc content than the calcareous chernozem soil.
Standard deviation of measured values in pH, soil plasticity, humus and nitrogen content significantly differ between the examined soil types. The soil plasticity, pH, humus, nitrogen and zinc content significantly differ among calcareous chernozem soil and meadow chernozem soil, but the difference in phosphorus content can be statistically proven only in case of Spring soil sampling.