<p>Važnost istraživanja fizičkih osobina ogleda se u tome, &scaron;to su neke od tih osobina prvo &scaron;to<br />se uočava na su&scaron;enom voću. Druge fizičke osobine spoznaju se tokom konzumiranja. Osim<br />toga, fizičke osobine su i od značaja prilikom projektovanja opreme za preradu<br />poljoprivrednih proizvoda. Predmet istraživanja doktorske disertacije su promene fizičkih<br />osobina dunje tokom osmotskog i konvektivnog su&scaron;enja. Istraživane su promene sledećih<br />osobina: vlažnosti, zapremine, mehaničkih osobina i boje. Kao dodatak osnovnim merenjima<br />obavljene su hemijska i senzorska analiza finalnog proizvoda. Eksperiment osmotskog<br />su&scaron;enja obavljen je kao dvofaktorni. Faktori eksperimenta su temperatura i koncentracija<br />osmotskog rastvora. U eksperimentu je kori&scaron;ćena dunja sorte leskovačka. Ovu sortu odlikuje<br />prijatna aroma, oblik i dimenzije pogodne za su&scaron;enje.<br />Disperzionom analizom rezultata merenja fizičkih osobina tokom eksperimenta<br />osmotskog su&scaron;enja potvrđeno je da izabrani nivoi temperature i koncentracije osmotskog<br />rastvora utiču na promenu vlažnosti dunje tokom 180 minuta osmotskog su&scaron;enja. U slučaju<br />povećanja mase suve materije disperzionom analizom potvrđen je statistički značajan uticaj<br />koncentracije i interakcije koncentracije i temperature na promenu ispitivane veličine.<br />Najintenzivnije promene vlažnosti i povećanja suve materije izmerene su u prvih 20 minuta<br />osmotskog su&scaron;enja.<br />Promena oblika dunje u formi kocke, do kojih dolazi tokom osmotskog su&scaron;enja je<br />anizotropna. Razlog anizotropnog skupljanja tkiva može biti orijentacija vlakana i<br />nehomogena struktura materijala. Promena zapremine izražena je zapreminskim skupljanjem<br />SV. Izvedena je jednačina kojom je utvrđena zavisnost promene zapremine od količine<br />razmenjene materije tokom osmotskog su&scaron;enja. Najveća promena zapremine izmerena je pri<br />osmotskom su&scaron;enju pri najvi&scaron;im vrednostima temperature i koncentracije osmotskog<br />rastvora.<br />Mehaničke osobine dunje tokom osmotskog su&scaron;enja predstavljene su sa dva pokazatelja,<br />otporno&scaron;ću na razaranje i modulom elastičnosti. Otpornost na razaranje je u ovoj tezi<br />originalno predstavljena parametrom f. Ovaj parameter predstvalja relativnu promenu sile<br />razaranja tokom osmotskog su&scaron;enja. Disperzionom analizom utvrđen je uticaj temperature<br />osmotskog rastvora na mehaničke osobine dunje. Osmotski rastvor temeperature 60oC<br />izaziva omek&scaron;avanje tkiva dunje. Međutim, omek&scaron;avanje tkiva dunje pozitivno utiče na<br />čvrstoću krajnjeg proizvoda. Kao drugi pokazatelj mehaničkih osobina upotrebljen je modul<br />elastičnosti. Promene modula elastičnosti slične su promenama f parametra. Na osnovu<br />promena oba pokazatelja mogu se doneti isti zaključci o uticaju faktora eksperimenta na<br />mehaničke osobine tkiva dunje.<br />Tkivo dunje je izloženo vazduhu tokom konvektivnog su&scaron;enja intenzivno menja boju. U<br />eksperimentu je upotrebljen sumpordioksid kao za&scaron;tita od tamnjenja tkiva. Ukupna promena<br />boje najveća je na uzorcima dunje koji su su&scaron;eni rastvorom koncentracije 65oBx. Međutim,<br />tokom konvektivnog su&scaron;enja ističe se pozitivan uticaj ovog tretmana na promenu boje dunje.<br />Veća količina saharoze koja se zadržava na povr&scaron;ini uzoraka dunje predstavlja barijeru<br />između između materijala i vazduha i spračava tamnjenje tkiva.<br />Regresionom analizom rezultata merenja promene vlažnosti, zapremine i boje pronađeni<br />su empirijski modeli koji opisuju merene veličine tokom osmotskog su&scaron;enja. Jednačine<br />odabrane za modelovanje promene vlažnosti pro&scaron;irene su uticajnim faktorima u<br />bezdimenzionalnom obliku. Pro&scaron;irenjem matematičkih modela stiče se njihova univerzalnost<br />u opsegu istraživanih vrednosti temperature i koncentracije osmotskog rastvora. Primenjeni<br />modeli mogu se uspe&scaron;no koristiti za predviđanje svih merenih veličina. Uspe&scaron;nost modela<br />potvrđena je visokim vrednostima koeficijenta korelacije i niskim vrednostima srednje<br />procentualne gre&scaron;ke.<br />Senzorskim analizama obavljenim panelnim ispitivanjem, uzorci tretirani osmotskim<br />rastvorom ocenjeni su kao kvalitetniji od onih koji su samo konvektivno osu&scaron;eni.<br />Poređenjem rezultata kvantitativnih i kvalitativnih analiza može se zaključiti da osmotsko<br />su&scaron;enje kao predtretman konvektivnom su&scaron;enju pozitivno utiče na kvalitet su&scaron;ene dunje kao<br />finalnog proizvoda.<br />&nbsp;</p> / <p>The importance of researching physical properties lies in the fact that some of these<br />properties are what we first notice about dried fruit. Other physical properties are<br />experienced during consumption. Moreover, physical properties are also important when<br />designing equipment for processing agricultural products. The subject of the research in this<br />doctoral dissertation is changes in physical properties of quince during osmotic and<br />convective drying. The investigation included changes in the following properties: moisture,<br />volume, mechanical properties and colour. Apart from the basic measurements, the research<br />also included chemical and sensory analyses of the final product. The experiment of osmotic<br />drying was performed as a two-factor experiment, while factors were the temperature and the<br />concentration of osmotic solution. The variety of quince used in the experiment was<br />&ldquo;Leksovačka&rdquo;, which is a variety with a pleasant aroma, and the shape and dimensions<br />suitable for drying.<br />Dispersion analysis of the measured results in the experiment of osmotic drying showed<br />that the temperature and concentration of osmotic solution affect the changes in moisture of<br />quince during 180 minutes of osmotic drying. In the case of the increased mass of dry matter,<br />analysis of variance pointed to statistically significant effect of concentration and interaction<br />of concentration and temperature on the change in the examined size. The most intense<br />changes in moisture and increase of dry matter were measured in the first 20 minutes of<br />osmotic drying.<br />The change of the shape of quince into the shape of a cube, which occurs during osmotic<br />drying, is anisotropic. The reason of anisotropic shrinkage of tissue can be fibre orientation<br />and inhomogeneous structure of the material. The volume change is expressed in volumetric<br />shrinkage SV. The equation derived was used to determine the dependence of the change in<br />volume on the amount of the matter exchanged during osmotic drying. The greatest change<br />in volume was measured during osmotic drying at the highest values of temperature and the<br />highest values of concentration of osmotic solution.<br />Mechanical properties of quince during osmotic drying were represented by two<br />indicators: resistance to rupture and modulus of elasticity. Resistance to rupture in this thesis<br />was originally presented by the parameter f. This parameter represents a relative difference of<br />force of rupture. Dispersion analysis determined the effect of the temperature of osmotic<br />solution on mechanical properties of quince. The solution temperature of 60oC causes<br />softening of the quince tissue. However, softening of the tissue has positive effects on<br />firmness of the final product. The other indicator of mechanical properties was modulus of<br />elasticity. The changes in the modulus of elasticity are similar to the changes of the<br />parameter f. The changes in both indicators lead to the same conclusions about the impact of<br />the factors of the experiment on the mechanical properties of quince tissue.<br />Quince tissue exposed to air changes its colour intensely. In this experiment, sulphur<br />dioxide is used as protection against darkening of the tissue. The total colour change was the<br />greatest in the quince samples dried using a solution with the concentration of 65oBx.<br />However, during convective drying one can see the positive impact of this treatment on the<br />colour change in quince. A larger amount of saccharose which is retained on the surface of<br />the samples acts as a barrier between the material and the air, preventing darkening of the<br />tissue.<br />Regression analysis of the measured results of the changes in moisture, volume and<br />colour, generated empirical models that describe the measured values during osmotic drying.<br />The equations selected for modelling of moisture changes were extended to include<br />influential factors in dimensionless form. What is achieved by extending the mathematical<br />models is universality of the models in the range of the investigated values of temperature<br />and concentration of osmotic solution. The used models can be successfully applied for<br />prediction of all of the measured values. The successfulness of the model is confirmed by<br />high values of the correlation coefficient and low values of the mean percentage error.<br />Sensory analyses performed using panel testing showed that the samples treated with osmotic<br />solution were evaluated to be of higher quality than the samples that were only convectively<br />dried. By comparing the results of quantitative and qualitative analyses, it can be concluded<br />that osmotic drying, as a pre-treatment to convective drying, positively affects the quality of<br />dried quince as a final product.</p>

<p>Su&scaron;enje dunje kao voćne vrste u praksi nije uobičajeno, zbog povi&scaron;ene vrijednosti<br />tvrdoće i čvrstoće. Prethodna istraživanja su&scaron;enja dunje, pokazala su da se osmotskim<br />su&scaron;enjem u okviru kombinovane tehnologije su&scaron;enja dobijaju povoljnije mehaničke<br />osobine su&scaron;enih proizvoda. Na osnovu plana obavljeni su eksperimenti osmotskog i<br />konvektivnog su&scaron;enja dunje u obliku četvrtina. Eksperiment osmotskog su&scaron;enja je<br />obavljen kao trofaktorni, gdje su uticajni faktori: temperatura rastvora, koncentracija<br />rastvora i vrijeme trajanja su&scaron;enja. TakoĎe, eksperiment konvektivnog su&scaron;enja je obavljen<br />kao trofaktorni, a uticajni faktori su: primjenjeni predtretman, temperature vazduha za<br />su&scaron;enje i brzina strujanja vazduha ispred sloja.<br />Na osnovu rezultata mjerenja eksperimenta osmotskog su&scaron;enja, zaključeno je da sa<br />porastom temperature i koncentracije rastvora postiže se veća brzina su&scaron;enja, &scaron;to se i<br />očekivalo. Disperzionom analizom osmotskog su&scaron;enja je ispitan uticaj faktora na brzinu<br />su&scaron;enja i zapreminsko skupljanje četvrtina dunje. Sa statističkom vjerovatnoćom od 99%<br />je dokazano da postoji uticaj svih faktora na brzinu su&scaron;enja uzoraka. Dokazano je sa<br />statističkom vjerovatnoćom od 99% da vrijeme trajanja osmotskog su&scaron;enja ima uticaj na<br />zapreminsko skupljanje četvrtina dunje, dok uticajni faktori temperatura i koncentracija<br />rastvora imaju uticaj sa statističkom vjerovatnoćom od 95%.<br />Analizom rezultata mjerenja veličina tokom eksperimenta konvektivnog su&scaron;enja<br />evidentno je da se sa vi&scaron;om temperaturom vazduha postiže brže sniženje vlažnosti<br />četvrtina dunje. Povećanjem vremena trajanja osmotskog predtretmana, smanjuje se<br />brzina konvektivnog su&scaron;enja. UtvrĎeno je da kori&scaron;ćenje osmotskog predtretmana sa<br />vi&scaron;om temperaturom rastvora i većom koncentracijom rastvora dovodi do smanjenja<br />brzine konvektivnog su&scaron;enja. Na osnovu disperzione analize konvektivnog su&scaron;enja sa<br />statističkom vjerovatnoćom od 99% dokazano je da postoje uticaji predtretmana i<br />temperature vazduha na brzinu su&scaron;enja i zapreminsko skupljanje četvrtina dunje. Uticaj<br />faktora brzine vazduha ispred sloja materijala nije dokazan disperzionom analizom, ali je<br />na osnovu kinetički krivih evidentan uticaj ovog faktora na brzinu su&scaron;enja, pri vi&scaron;im<br />vlažnostima materijala i vi&scaron;oj temperaturi konvektivnog su&scaron;enja. Najvjerovatniji razlog<br />ovakvih rezultata disperzione analize su male vrijednosti brzine vazduha za su&scaron;enje,<br />odnosno njihova mala razlika vrijednosti (0,5 m/s).<br />Kinetika prenosa mase tokom kombinovane tehnologije su&scaron;enja dunje u formi<br />četvrtine je matematički opisana, modelovanjem kinetike osmotskog su&scaron;enja i kinetike<br />konvektivnog su&scaron;enja. U okviru kinetike osmotskog su&scaron;enja četvrtina dunje, obavljeno je<br />matematičko modelovanje promjene vlažnosti u odnosu na suvu bazu i modelovanja<br />zapreminskog skupljanja. Za kinetiku konvektivnog su&scaron;enja četvrtina dunje, obavljeno je<br />matematičko modelovanje promjene vlažnosti u odnosu na suvu bazu tokom vremena<br />konvektivnog su&scaron;enja. Za svaku veličinu koja se modeluje usvojeno po tri matematička<br />modela, a modeli su pro&scaron;ireni uticajnim faktorima u bezdimenzionom obliku. Izvedeni<br />modeli su imali dobro slaganje sa eksperimentalnim rezultatima, &scaron;to pokazuju visoke<br />vrijednosti koeficijente korelacije. Primjena svih modela je jednostavna, gdje je uz pomoć<br />standardnih računara moguće brzo izračunavanje svih modelovanih veličina.<br />Primjenom osmotskog predtretmana u kombinovanoj tehnologiji su&scaron;enja dunje,<br />dobijaju se neke pozitivne osobine su&scaron;enog proizvoda. Smanjenje zapremine je manje<br />izraženo, nego primjenom samo konvektivnog su&scaron;enja. Vlažnost u voćnom tkivu je<br />ravnomjernije rasporeĎena i manje je presu&scaron;ivanje spoljnjih slojeva voćnog tkiva.<br />Stvaraju se manji unutra&scaron;nji naponi izmeĎu slojeva tkiva, uslijed čega nastaju manje<br />deformacije oblika. U povr&scaron;inskom sloju voćnog tkiva postoje adsorpcione veze vlage,<br />rastvorka i suve materije, a ove veze utiču na povećanje vrijednosti vlažnosti pri kojima<br />se osu&scaron;eni proizvod bezbjedno skladi&scaron;ti.</p> / <p>Drying of the quince as a fruit species is not common in practice due to its increased hardness<br />and firmness. Previous researches on quince drying have indicated that osmotic drying, within<br />the combined drying technology, enables favourable mechanical properties of dried products.<br />Planned experiments of the osmotic and convective drying of quince quarters were conducted.<br />The osmotic drying experiment was based on three significant experimental factors: the<br />temperature of osmotic solution, the concentration of osmotic solution, and the duration of<br />osmotic drying. The convective drying experiment was also based on three experimental<br />factors entailing the applied pretreatment, the temperature of drying air and the velocity of<br />drying air in front of material layers.<br />The measurement results obtained during the osmotic drying experiment indicate that an<br />increase in the temperature and the concentration of osmotic solution accelerates the drying<br />process, as expected. A dispersion analysis of the osmotic drying indicated the effects of<br />experimental factors on the drying speed and the volume shrinkage of quince quarters. With a<br />statistical probability of 99%, it was proven that all factors influence the speed of drying.<br />Moreover, with a statistical probability of 99%, it was proven that the duration of osmotic<br />drying influences the volume shrinkage of quince quarters, whereas the significant factors such<br />as the temperature and the concentration of osmotic solution exert influence with a statistical<br />probability of 95%.<br />The analysis of measurement results obtained during the convective drying experiment shows<br />that an increase in the air temperature accelerates a decrease in the moisture content of quince<br />quarters. An increase in the duration of osmotic pretreatment decelerates the convective drying<br />process. It was determined that the application of the osmotic pretreatment with higher<br />solution temperature and concentration decelerates the convective drying. On the basis of a<br />dispersion analysis of the convective drying with a statistical probability of 99%, it was proven<br />that the pretreatment and the air temperature affect the speed of drying and the volume<br />shrinkage of quince quarters. The effects of the air velocity in front of the material layer was<br />not determined by means of the dispersion analysis, nevertheless kinetic curves indicate the<br />influence of this factor on the drying speed, especially in the instance of higher moisture<br />content of the material and higher temperature of the convective drying. The most probable<br />causes of such dispersion analysis results are low values of the drying air velocity, i.e. a slight<br />difference in the values (0.5 m/s).<br />The kinetics of mass transfer during the combined drying of quince quarters was<br />mathematically described by means of the modelling of the kinetics of osmotic drying and the<br />kinetics of convective drying. The kinetics of osmotic drying of quince quarters was expressed<br />via the mathematical modelling of moisture content change in relation to dry basis and the<br />modelling of volume shrinkage. The kinetics of convective drying of quince quarters was<br />expressed via the mathematical modelling of moisture content change in relation to dry basis<br />during the convective drying. Three mathematical models were established for every modelled<br />value, and the models were extended by significant non-dimensional experimental factors. The<br />developed models had a good fit with the experimental results, which was indicated by the<br />high values of the correlation coefficient. The application of all models is simple and standard<br />personal computers can be used for rapid calculations of modelled values.<br />The application of the osmotic pretreatment in the combined quince drying enables<br />favourable properties of dried products. Volume shrinkage is slighter in comparison with the<br />convective quince drying. The moisture content in the fruit tissue is more evenly distributed<br />and the dehydration of the outer layers of the fruit tissue is lower. The tension between the<br />layers of the tissue is reduced thus reducing the shape defects. Within the surface layers of fruit<br />tissues, the adsorption bonds of moisture, solute and dry matter are formed. These bonds<br />increase the moisture content value, which enables the safe storage of dry products.</p>

In ihrer Rede 'Heimat kriegt uns alle' hinterfragt die deutsche TV-Journalistin und Fernsehmoderatorin, warum die Zeichen auf Rückzug und Absicherung stehen. Amerika, Spanien, Großbritannien, Deutschland. Angesichts der weltpolitischen Verwerfungen schließen sich die Reihen. Offene Grenzen werden zur Bedrohung. Die Bewahrung der „eigenen Kultur“ gewinnt an Bedeutung. Das „Wir“ und das „Ihr“ sorgt für Spannungen zwischen befreundeten Nationen, und innerhalb der eigenen Landesgrenzen tun sich Gräben auf zwischen Traditionalist*innen und Modernisierer*innen. Im Kampf um die Deutungshoheit, wem die Heimat gehört, nimmt die Diskussion bizarre Züge an: Ein bisschen Blut. Ein bisschen Boden. Und ein bisschen Bullshit. Heimat kriegt uns alle. Aber wie? Die Zählung der Dresdner Rede ist in der Publikation fälschlicherweise mit 04.2018 angegeben, tatsächlich handelt es sich um die 3. Rede des Jahres 2018.