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Search Results: 1 - 10 of 201157 matches for " Zlatkovi? Branislav P. "
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Kinetics of drying and quality of the apple cultivars Granny Smith, Idared and Jonagold
Paunovi? Dragana M.,ZlatkoviBranislav P.,Mirkovi? Du?ica D.
Journal of Agricultural Sciences , 2010, DOI: 10.2298/jas1003261p
Abstract: Apple is nutritionally valuable and present as fresh fruit in human nutrition throughout the year. Also apple is a raw material in food processing, primarily in the production of juices, nectars, refreshing soft drinks, marmalades, jams, compotes, apple cider vinegar and dried fruits. In the last decade on the world market there is a great interest in dried apple products (commercially called apple chips). During preservation by drying the technological process aimed at the final product of optimal quality is required. The subject of this paper is the kinetics of the apple cv. Granny Smith, cv. Idared and cv. Jonagold drying in laboratory dehydrator for the purpose of pinpointing at which level of humidity the maximum speed of evaporation is achieved and at which level of humidity apple slices begin to change in colour and geometric shape. Parameters of the drying process were the same for all three cultivars, 3hrs at air temperature of 70oC and 5hrs at air temperature of 50o. The amount of evaporated water is expressed in relative and absolute units of measure. The purpose of this paper is to determine which one of the three tested cultivars provides the best properties for drying, i.e. in terms of oxidation of polyphenolic compounds to find the cultivar which will provide that the final product is technologically and organoleptically the most acceptable. The results showed that the sample cv. Granny Smith expressed the least oxidation of polyphenolic compounds (browning), curved edges and shrivelled apple slices. After that the sample cv. Jonagold followed. The sample cv. Idared showed the worst results. Following the drying kinetics of all three samples, it can be concluded that the cultivars Granny Smith and Jonagold were achieving the lower maximum speed of evaporation, unlike the cultivar Idared. The cultivars Granny Smith and Jonagold have attained consistent drying and in this way the technological process was finished with a smaller temperature stress for plant tissue, resulting in a much better quality of the final product.
Antioxidant activity, the content of total phenols and flavonoids in the ethanol extracts of Mentha longifolia (L.) Hudson dried by the use of different techniques
Stanisavljevi? Dragana M.,Stoji?evi? Sa?a S.,?or?evi? Sofija M.,ZlatkoviBranislav P.
Chemical Industry and Chemical Engineering Quarterly , 2012, DOI: 10.2298/ciceq110919017s
Abstract: In this study, we have examined the yield of extracted substances obtained by means of extraction using 70 % ethanol (v/v), the content of total phenols and flavonoids, as well as the antioxidant activity of the extracts obtained from the samples of the herbs dried by means of different techniques. Wild mint Mentha longifolia (L.) Hudson was dried naturally in a laboratory oven at a temperature of 45 °C and in an absorptive low temperature condensation oven at 35°C. The highest yield of extracts was obtained from the naturally dried herbs and the lowest from the herbs dried in the low temperature condensation drying oven. The content of total phenols and flavonoids was determined by spectrophotometric methods with an FC reagent and by the complexation reaction with aluminium-chloride, respectively. The extract of the naturally dried herbs had the highest overall content of phenols (113.8±2.0 mg of gallic acid/g of the dry extract) and flavonoids (106.7±0.3 mg of rutin/g of the dry extract). The highest antioxidant activity determined by the FRAP and DPPH assay was determined in the extracts obtained from naturally dried herbs (2.76±0.15 mmol Fe2+/mg of the dry extract and EC50=0.022±0.001 mg/ml), while the lowest was obtained from the extracts of herbs dried in the laboratory oven (1.13±0.11 mmol Fe2+/mg of the dry extract and EC50=0.033±0.001 mg/ml). The HPLC-DAD analysis result show that the greatest content of phenolic compounds show extract obtained from naturally dried plant material. The dominant phenolic component in the all extracts is Kaempferol 3-O-glucoside. The content of all phenolic compound strongly depend on the drying conditions.
From a smokehouse to a vacuum dehydrator
ZlatkoviBranislav,Vuli? Todor
Journal of Agricultural Sciences , 2004, DOI: 10.2298/jas0401131z
Abstract: The tradition of fruit dehydration in Serbia has been long and anviable. It seems that Serbian machine-building in the area of fruit processing technology has given its greatest contribution in this field. It has been one 100 years since the smoking house of Mr Stokovic, PhD was announced to be the best and the most promising plum dehydrator at the open competition organized in Top ider by the Ministry of Agriculture. It was the first real almost continual fruit dehydrator where plums were moved at certain intervals closer and closer to the source of heat. Such a concept of plum dehydration from lower to higher temperatures was held on even later in perhaps our most famous dehydrator CER. Even the smoky smell was retained but liquid fuel was used for technical purposes. For a long time, it has been a well- known fact that vacuum dehydration has many advantages. In our country there have been many attempts to make fruit dehydrator of greater capacities in which vacuum would be used. Of course, there have been many problems, both technical and technological, but today a hundred years after accepting Stojkovic’s smokehouse, it is our great honor to present to you the results of plum dehydration in a home-made vacuum condensation dehydrator. We hope that now path is widely open to high quality dehydration, and not only for that plum, but for fruit susceptible to oxidation which is the reason our food industry has not produced it so far. This is probably a farewell to the most dangerous, but for the product quality, the most necessary operation - sulphuration.
Sinalbin degradation products in mild yellow mustard paste
Paunovi? Dragana,?olevi?-Knudsen Tatjana,Krivokapi? Mirjana,ZlatkoviBranislav
Hemijska Industrija , 2012, DOI: 10.2298/hemind110627055p
Abstract: Sinalbin degradation products in mild yellow mustard paste were investigated. The analyzed material consisted of a mild yellow mustard paste condiment and ground white mustard seeds which were originally used in the mustard paste production process. The samples were extracted in a Soxhlet extraction system and analyzed by gas chromatography - mass spectrometry (GC-MS) technique. The only sinalbin degradation product in ground mustard seeds was 2-(4-hydroxyphenyl)acetonitrile. The most abundant sinalbin degradation product in yellow mustard paste was 4-(hydroxymethyl)phenol. Other compounds identified in this sample were: 4-methyl phenol, 4-ethyl phenol, 4-(2-hydroxyethyl)phenol and 2-(4-hydroxyphenyl) ethanoic acid.
Analysis of drying potato kinetics in laboratory conditions
Zlatkovi? B.P.,Rajkovi? Milo? B.
Journal of Agricultural Sciences , 2005, DOI: 10.2298/jas0502161z
Abstract: Chemistry is in its nature a fundamental science, but nowadays its results are increasingly used in practice. In such a way, many syntheses of important nutrition and industrial compounds (chemical technology), or destruction of harmful substances (chemical ecology) have been developed. The analytic part of chemistry (analytical chemistry) has found a significant usage even in optimization of technological processes of food technology. One of the oldest ways of food preservation is drying (dehydration). The basis of this process of preservation is to vaporize water, to dry enough the product, in order to stop the activity of enzymes and possibility of microorganisms’ development. Water in agricultural products is not free but bound to dry matter. Therefore, for its vaporizing it is necessary to bring enough heat. The part of the brought heat is used for vaporizing water, but one part of it becomes the energy for activation of several chemical reactions that decrease the nutritive values and the quality of future food. Therefore, the important engineering problem emerges: determination of optimal conditions for drying. For optimization of technological process of drying, it is necessary to do mathematical modeling of dependence of water vaporizing speed from environmental conditions beforehand. The aim of this paper is to determine potato pieces drying kinetics in laboratory dryer, in order to determine the optimal conditions for its industrial dehydration. It was established that in the first quarter of the time of drying evaporated 28.3% of total evaporation of water, and then in order by quarters: 53%, 14.1% and 4.6%, respectively. The greatest speed of drying was realized at moisture of potatoes about 50%.
Urban agglomerations on main development axes as poles of demographic revitalization of Serbia
Stojanovi? Branislav P.,Vojkovi? Gordana
Stanovni?tvo , 2005, DOI: 10.2298/stnv0504061s
Abstract: Significant geographical-demographic changes are characteristic for the region of Serbia in the second half of the 20th century, which were caused by a dynamic primary urbanization process, namely intense migrational trends between village and town. Expansion zones were formed around urban centers with total intense growth (both demographic and economic), which are mainly found in land areas of main development axes, whereby the (Sava) Danube-Morava one is the most significant. The importance of this development axis (not only in the demographic sense) is indicated by the fact that in this region (composed of districts which are located in the corridor zone) 3794.8 thousand people lived in 2002, which represents 50.6% of the population of Central Serbia and Vojvodina. Taking into consideration the territory it consists of, this zone is populated twice as much in average than the region of Serbia (without Kosovo) as a whole. Along with that, out of the five urban areas with more than 100 thousand people (large urban centers), four are located in this zone (Subotica, Novi Sad, Belgrade and Ni ) and only Kragujevac is located somewhat on the outskirts in relation to it, but in its immediate proximity. Large town centers in corridor zone X concentrated as much as 41% of the Republic urban population in 2002. At the same time, a network of 32 settlements in the land area of this main development axis of Serbia which belong to the category of small and medium size towns, and which cover about 16% of the republic urban population should be added to this. Consequently this zone, as other concentrated population zones, which are formed around secondary development axes on the territory of Serbia, is identified as a region with significant population potential. For that very reason, there was an attempt in this paper to determine the role and significance of urban agglomerations on main development axes for possible demographic revitalization of Serbia. The significance of urban population arises from its quantitative and especially qualitative (structural) characteristics. This category of population of the Republic realizes significant growth (more than 10%) in the last two inter-census decades (1981-2002) regardless of the effects of demographic and socio-economic transitions and geo-political changes and their mainly negative influences as opposed to the total population of this region which realizes an apparent drop (of 3%). The drop of rural population is even more obvious (by about 16%) so its (future) role in possible demographic revitalization of Serbia
The importance and potentials of X corridor in the European traffic system
Stojanovi? Branislav P.,Todorovi? Marina J.
Glasnik Srpskog Geografskog Dru?tva , 2004, DOI: 10.2298/gsgd0402125s
Abstract: In the network of multimodular corridors, but also in the European traffic system on the whole, corridor X has a very important role more in respect of its position and potentials and less regarding the degree of it valuation. It is particularly so since it represents a section of the intercontinental (land) link between Europe and Near and Middle East. At the same time, this corridor is also a dominant axis of development in the majority of SE European countries, as well as a major component of complex spatial-functional transformations that occur within them. That, inter alias, means that the pace of overall development of these parts will depend both on the pace of the overall valuation of potentials this corridors has (and represents), as well as the strengthening of its role as a major element of intra- and inter-regional linking of this part of European continent.
Globalization and regionalisation: Determinants of the transformation and the process of the integration of the geo-space
Todorovi? Marina J.,Stojanovi? Branislav P.
Glasnik Srpskog Geografskog Dru?tva , 2005, DOI: 10.2298/gsgd0501167t
Abstract: The two processes that, basically since the emergence of the classic civilizations, determine major changes in the basic spatial structures in the world are, de facto, of antipode basic characteristics (globalization and regionalisation), but it is often the case that there are elements with traits of complementarily. They have crucial effect on development and integration of geo-spaces and many research results indicate that, depending of the stage of the development, both processes were present in the geo-space in various forms in almost all the phases of its development and that they have contributed to establishment of all the new spatial-structural relations. The subject of this analyses is, among other issues, a brief genesis of these two processes, including identification of their main starters and effects. Besides from that, there is a special attention paid to the role of the traffic as their basic element and one of the important initiators and its role in those parts of the European continent that are not yet included by these processes of crucial changes of the geo-space as the whole.
Spatial distribution of local currents of massless Dirac fermions in quantum transport through graphene nanoribbons
Liviu P. Zarbo,Branislav K. Nikolic
Physics , 2007, DOI: 10.1209/0295-5075/80/47001
Abstract: We employ the formalism of bond currents, expressed in terms of the nonequilibrium Green functions, to image the charge flow between two sites of the honeycomb lattice of graphene ribbons of few nanometers width. In sharp contrast to nonrelativistic electrons, current density profiles of quantum transport at energies close to the Dirac point in clean zigzag graphene nanoribbons (ZGNR) differs markedly from the profiles of charge density peaked at the edges due to zero-energy localized edge states. For transport through the lowest propagating mode induced by these edge states, edge vacancies do not affect current density peaked in the center of ZGNR. The long-range potential of a single impurity acts to reduce local current around it while concurrently increasing the current density along the zigzag edge, so that ZGNR conductance remains perfect $G=2e^2/h$.
Extrinsic Entwined with Intrinsic Spin Hall Effect in Disordered Mesoscopic Bars
Branislav K. Nikolic,Liviu P. Zarbo
Physics , 2006, DOI: 10.1209/0295-5075/77/47004
Abstract: We show that pure spin Hall current, flowing out of a four-terminal phase-coherent two-dimensional electron gas (2DEG) within inversion asymmetric semiconductor heterostructure, contains contributions from both the extrinsic mechanisms (spin-orbit dependent scattering off impurities) and the intrinsic ones (due to the Rashba coupling). While the extrinsic contribution vanishes in the weakly and strongly disordered limits, and the intrinsic one dominates in the quasiballistic limit, in the crossover transport regime the spin Hall conductance, exhibiting sample-to-sample large fluctuations and sign change, is not simply reducible to either of the two mechanisms, which can be relevant for interpretation of experiments on dirty 2DEGs [V. Sih et al., Nature Phys. 1, 31 (2005)].
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