<p>Postojanje ugljeničnih nanocevi (UNC), kao jedne od brojnih alotropskih modifikacija ugljenika, zabeleženo je jo&scaron; pre vi&scaron;e od pola veka. Međutim, do prave eksplozije<br />interesovanja za ovu vrstu nanomaterijala je do&scaron;lo tek 1991. godine kada ih je &quot;ponovo&quot; otkrio japanski naučnik S. Iijima. Od tada, zbog svojih izuzetnih fizičko-hemijskih osobina, UNC počinju da privlače pažnju naučne javnosti i spajaju istraživače iz različitih oblasti sa zajedničkim imeniteljem - nanotehnologija. Otkriće UNC je u znatnoj meri omogućilo razvoj visoke tehnologije u oblastima kao &scaron;to su elektronika, optika, kompozitni materijali, kataliza, za&scaron;tita životne sredine, itd. Danas, primena nanocevi sve vi&scaron;e doprinosi lak&scaron;oj implementaciji principa održivog razvoja u pomenute oblasti. Kataliza je polje od dvostrukog interesa, jer je jedan od načina dobijanja UNC upravo katalitički, a osim toga i same cevi su interesantne kao nosač novog katalizatora.<br />Istraživanje čiji su rezultati prikazani u okviru ove doktorske disertacije je obuhvatilo vi&scaron;e oblasti proučavanja UNC, počev&scaron;i od razvoja metode za njihovu sintezu, preko preči&scaron;ćavanja i funkcionalizacije finalnog proizvoda, pa do primene nanocevi u dva procesa od značaja za oblast za&scaron;tite životne sredine.</p><p>Razvoj katalitičke metode sinteze UNC započet je primenom vertikalnog cevnog kvarcnog reaktora, iz CO i CH4 kao izvora ugljenika, pri čemu su u reakciji testirani<br />monometalni katalizatori na bazi Fe, Co i Ni na Al2O3 kao nosaču (I serija katalizatora). Rezultati ovih preliminarnih eksperimenata su pokazali malu aktivnost I serije monometalnih katalizatora, &scaron;to se može pripisati, kako neadekvatnoj hidrodinamici reaktora i lo&scaron;e odabranim reakcionim parametrima, tako i neodgovarajućoj veličini katalitičkih čestica i načina njihovog pakovanja u vertikalnom<br />reaktoru. Shodno tome, u cilju postizanja boljeg prinosa nanocevi, dalji eksperimenti sinteze izvedeni su u horizontalnom reaktoru u struji C2H4 i u prisustvu II serije<br />monometalnih katalizatora sa Al2O3 i SiO2 kao nosačima, koji se u odnosu na I seriju razlikuju po udelu aktivne faze i veličini čestica katalizatora (pra&scaron;kast oblik). Katalizatori II serije su pokazali zadovoljavajuću aktivnost u reakciji sinteze UNC, a rezultati karakterizacije dobijenih uzoraka nanocevi ukazuju na različit uticaj nosača katalizatora na morfologiju sintetisanih nanocevi. Shodno ostvarenom prinosu ugljenika, a u cilju optimizacije reakcionih parametara, katalizator na bazi Fe sa SiO2 kao nosačem je odabran kao reprezentativan za ispitivanje uticaja vremena trajanja sinteze UNC, kao i zapreminskog udela C2H4 u sme&scaron;i sa azotom, na prinos<br />nanocevi i selektivnost procesa.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Optimizacija reakcionih uslova je u daljoj fazi rada dovela do uvođenja bimetalnih katalizatora sa istim tradicionalnim nosačima &ndash; Al2O3 i SiO2. Najveći prinos ugljenika ostvaren je na katalizatorima sa Fe i Co kao aktivnom fazom, bez obzira na vrstu nosača. UNC sintetisane na pomenutim katalizatorima su karakterisane u cilju<br />ispitivanja uticaja primenjenih nosača na njihove fizičkohemijske osobine, pa je shodno tome i predložen vr&scaron;ni mehanizam njihovog rasta. Rezultati ispitivanja kvaliteta sintetisanih UNC su ukazali da primena SiO2, kao nosača katalizatora, za razliku od Al2O3, favorizuje rast UNC boljeg povr&scaron;inskog i ukupnog kvaliteta. S obzirom na raznolikost mogućnosti primene UNC, istraživanja u tom smeru zahtevaju čiste UNC, pa su shodno tome proizvodi sinteze preči&scaron;ćeni metodom tečne oksidacije. Rezultati fizičko-hemijske karakterizacije preči&scaron;ćenih UNC su ukazali na efikasnost primenjene metode sa aspekta uklanjanja prisutnog katalizatora, ali i na njen različit uticaj na strukturu, odnosno kvalitet preči&scaron;ćenih uzoraka. Kao posledica promena unutar strukture UNC, kao i različitog stepena njihove funkcionalizacije, ukupni kvalitet preči&scaron;ćenih nanocevi je, u zavisnosti od primenjenog nosača katalizatora, promenjen u odnosu na odgovarajuće nepreči&scaron;ćene uzorke.<br />Poslednjih godina se posebna pažnja poklanja nanomaterijalima koji se mogu primeniti za uklanjanje različitih polutanata iz životne sredine, kako u funkciji adsorbenata, tako i u funkciji katalizatora. U okviru ove doktorske disertacije obuhvaćena je primena UNC kao adsorbenta za uklanjanje insekticida tiametoksama iz vode, kao i njihova primena kao nosača katalizatora u reakciji<br />denitracije vode. Rezultati eksperimenata adsorpcije su pokazali da UNC, prethodno tretirane u ccHNO3, predstavljaju dobar adsorbent za uklanjanje insekticida tiametoksama iz vodenog rastvora. Odabir procesnih parametara za proučavanje kinetike adsorpcije, adsorpcione ravnoteže, kao i termodinamike procesa izvr&scaron;en je primenom frakcionog faktorskog dizajna na dva nivoa, 5 1 V 2 , a dobijeni rezultati su ukazali da je pomenuti proces adsorpcije spontan i kontrolisan uglavnom unutra&scaron;njom difuzijom molekula insekticida u mezopore uzorka UNC. Performanse katalizatora sa UNC kao nosačem su testirane u reakciji katalitičke denitracije, pri čemu su dobijeni rezultati pokazali da se novoformirani katalizator karakteri&scaron;e zadovoljavajućom disperzno&scaron;ću sa udelombimetalnih Pd-Cu nanočestica koje omogućavaju 60% konverzije nitratnog jona.</p> / <p style="text-align: justify;">The existance of carbon nanotubes (CNTs), as one of the carbon allotropes, was noted over half century ago. However, the true interest for these nanomaterials appeared at 1991, when they were &quot;redescovered&quot; by Japanese scientist S. Iijima. Since then, due to their unique physico-chemical properties, CNTs begin to attract attention of the scientific community and to gather researchers from different areas within the common field of interest &ndash; nanotechnology. The CNTs discovery substantially enabled the high technology development in the fields such as electronics, optics, composite materials, catalysis, environmental protection, etc. Nowdays, the application of nanotubes is increasingly contributing to easier implementation of sustainable development principles in the above mentioned areas. Catalysis is the field of double interest &ndash; one of the CNTs synthesis method is catalytical, and the nanotubes can also be used as the support of the new catalyst.<br />The research, which results are shown within this PhD Thesis, includes few different CNTs research fields, starting from the synthesis method development, over the purification and functionalization of the final product, to the application of<br />nanotubes in two processes of significance for the field of environmental protection.<br />The development of the CNTs catalytic synthesis method was started by the use of vertical quartz tube reactor, in the flow of CO and CH4 as the carbon source, and in the presence of monometallic catalysts based on Fe, Co and Ni at Al2O3 as the support (the first series of catalysts). The results of these preliminary experiments have shown the low activity of these monometallic catalysts, which can be attributed to the inadequate reactor hydrodynamics and selected reaction parameters, as well as the inadequate size of the catalytic particles and the type of their packing in the vertical reactor. Consequently, in order to achieve the higher nanotubes yield, further synthesis experiments were carried out in a horizontal reactor in the flow of C2H4 as the carbon source, and in the presence of the second series of monometallic catalysts with Al2O3 and SiO2 as the supports. The catalysts of the second series have shown satisfactory activity in the CNTs synthesis reaction, and the results of the obtained samples characterization idicate a different influence of the catalyst support on the synthesized CNTs morphology. In order to optimize the reaction parameters, Fe/SiO2 catalyst was chosen as a representative to examine the effect of the CNTs synthesis duration, as well as the volume percentage of C2H4 in the mixture with nitrogen to the CNTs yield and process selectivity. In a further phase of work, the optimization of thereaction parameters led to the introduction of the bimetallic catalysts with the same traditional supports, Al2O3 and SiO2. The highest carbon yield was achieved over Fe, Co based catalysts, regardless of the type of the catalyst support. CNTs synthesized over the above mentioned catalysts were characterized in order to study the effect of the used supports on their physico-chemical properties, and consequently the CNTs tip growth mechanism was proposed. The results of quality examination of the synthesized CNTs showed that the use of SiO2, as a catalyst support, unlike Al2O3, favors the growth of nanotubes of better surface and overall crystalline quality. In view of the diversity of possible CNTs applications, investigation in that direction requires purified CNTs and accordingly the final CNTs products were purified by liquid oxidation method. The results of physico-chemical characterization of the purified CNTs showed that the applied purification method was effective in terms of removing the present catalyst, but on the other hand it had different influence on the structure and quality of the purified samples. As a consequence of CNTs structural changes, as well as their different degree of functionalization, the overall crystalline quality of the purified nanotubes, originating from different catalyst supports, was changed in comparison to the corresponding unpurified samples. Over the past few years, special attention was focused on<br />nanomaterials that can be applied as adsorbents or catalysts for the removal of various pollutants from the environment. This PhD Thesis considers the use of CNTs, as adsorbent, for the removal of insecticide thiamethoxam from water, as well as their use as catalyst support for water denitration reaction. The results of adsorption experiments have shown that the CNTs, pretreated in ccHNO3, represent a good adsorbent for the removal of thiamethoxam from the aqueous solutions. The<br />selection of the process parameters in order to study the adsorption kinetics and equilibrium, as well as the thermodynamics of the process, was conducted using the<br />fractional factorial design at two levels, 5 1 V 2 . The obtained results showed that the adsorption process is spontaneous and controlled mainly by an internal diffusion of molecules of insecticide in the mesopores of CNTs. The performance of the catalyst with the CNTs as the support were tested in catalytic water denitration reaction, whereby the results showed that the newly formed catalyst is characterized by satisfactory dispersion of Pd-Cu bimetallic nanoparticles which enable the 60% conversion of nitrate ions.</p>

<p>Istraživanja u okviru disertacije usmerena su na razvoj vakuumskog postupka su&scaron;enja voća. Konstruisan je prototip laboratorijske vakuumske su&scaron;are i optimizovan proces su&scaron;enja vi&scaron;anja i borovnica. U cilju optimizacije procesa su&scaron;enja ispitan je uticaj nezavisno promenljivih procesa, temperature i pritiska, na parametre kvaliteta osu&scaron;enog voća (aktivnost vode, sadržaj ukupnih fenola, ukupnih monomernih antocijana i vitamina C, antioksidativnu aktivnost, promenu boje, teksturu i sposobnost rehidratacije). Proces su&scaron;enja optimizovan je kori&scaron;ćenjem metode odzivnih povr&scaron;ina (engl. Response Surface Methodology, RSM).<br />Rezultati istraživanja pokazuju da tehnika su&scaron;enja voća u vakuumu daje odlične rezultate u pogledu očuvanja visokovrednih komponenata voća i ima perspektivu za &scaron;iru primenu u zanatskim i poluindustrijskim postrojenjima.</p> / <p>Research in the framework of the thesis focuses on the development of fruit vacuum-drying process. Laboratory vacuum dryer prototype was constructed. Cherries and blueberries vacuum drying process was optimized. In order to optimize the drying process, the influence of independent variables of the process (temperature and pressure) on the quality parameters of dried fruit (water activity, total phenol content, total monomeric anthocyanins and vitamin C, antioxidant activity, colour change, texture, and rehydration capability) was investigated. The drying process was optimized using Response Surface Methodology (RSM).<br />There is the possibility of application of the results in plants at semi-industrial and industrial level.</p>

<p>U okviru disertacije analiziran je uticaj genetskih, ekolo&scaron;kih i mikroklimatskih faktora<br />tokom tri proizvodne godine na sastav glutena i tehnolo&scaron;ki kvalitet 16 sorti p&scaron;enica<br />koje su godinama zastupljene u sortimentu Srbije, a koje su bile proizvedene na istom<br />lokalitetu. Da bi se ispitao tehnolo&scaron;ki kvalitet i sastav glutena, upotrebljene su, kako<br />tradicionalne, tako i savremene metode; urađena je elektroforetska analiza gluteninskih<br />i glijadinskih podjedinica, sadržaj slobodnih &ndash;SH i &ndash;NH grupa, probno pečenje i<br />objektivno je ocenjen kvalitet dobijenog hleba u cilju formiranja baze podataka za<br />statističku analizu. Zbog obimnosti rezutata i činjenice da su pokazatelji određeni u<br />različitom broju ponavljanja uslovljenim potrebnom količinom uzorka, uobičajenim<br />brojem ponavljanja, reproduktivno&scaron;ću metoda, urađena je PCA analiza na osnovu koje<br />je izvr&scaron;en odabir najvažnijih pokazatelja. Dodatno, primenjena je Analiza značajnosti u<br />odnosnu na: klimatske faktore koji su uslovljeni proizvodnom godinom, genetske<br />faktore koji su uslovljeni genetskom slično&scaron;ću ispitivanog sortimenta p&scaron;enice, kao i<br />ekolo&scaron;kim faktorima koji se ogledaju preko različitog nivoa neodvojivih primesa koji<br />su definisani frekvencionom analizom. Cilljevi istraživanja omogućili su da se:<br />&ndash;utvrdi kako i na koji način mikroklimatski uslovi koji su vladali u tri proizvodne<br />godine, a pogotovo ki&scaron;no i nestabilno vreme u periodu od cvetanja p&scaron;enice pa sve do<br />pune zrelosti, utiču na sastav glutena i tehnolo&scaron;ki kvalitet ispitivanih sorti p&scaron;enice,<br />&ndash;utvrdi kako i na koji način ekolo&scaron;ki faktori, definisani prisutvom tri različita nivoa<br />proklijalih, steničavih, fuzarioznih i tamnokličnih zrna, utiču na sastav glutena i<br />tehnolo&scaron;ki kvalitet ispitivanih sorti p&scaron;enice<br />&ndash;utvrdi kako genetski faktori, definisani preko razlika u HMW&ndash;GS koje ispitivane<br />sorte sadrže, odnosno ne sadrže na Glu A1, Glu D1 lokusu i identičnom HMW&ndash;GS<br />sastavu, utiču na sastav glutena i tehnolo&scaron;ki kvalitet ispitivanih sorti p&scaron;enice.<br />Dobijeni rezultati predstavljaju jednu kompleksnu analizu koja je obuhvatila veliku<br />bazu ispitivanih pokazatelja i bliže odredila kako pojedinačni genetski, mikroklimatski<br />i ekolo&scaron;ki faktori utiču na sastav glutena i tehnolo&scaron;ki kvalitet p&scaron;enice.</p> / <p>In the Ph. D. Thesis was analyzed the impact of genetic, environmental and<br />microclimatic factors that prevailed during the three production years on gluten<br />composition and technological quality of 16 wheat varieties that are present in the<br />assortment of Serbia. Also, all wheat varieties were produced at the same location. The<br />traditional and sofisticated methods are used, electrophoretic analysis of glutenin and<br />gliadin subunits was performed, the content of free-SH and-NH groups are determined,<br />baking test and objective quality of the obtained bread are evaluated to examine the<br />technological quality of wheat and composition of gluten. The gained results are used<br />to established a database for statistical analysis. Due to the numerous data and the fact<br />that the properties measured in different number of repetitions which are qualifed by<br />sample amount, the usual number of repetitions, reproductivity method PCA was<br />performed toward the selection of the most important properties. After that was done<br />ANOVA in the respective to climatic factors that charatcterized the production year,<br />the genetic factors that are caused by genetic similarity of the exmined cultivars of<br />wheat and environmental factors that are reflected through the different levels of<br />inseparable impurities, which are defined by frekvency analysis. Specific objectives of<br />the study enable to:<br />&ndash;determine how microclimatic conditions that prevailed in the three production<br />years, especially the rainy and instable weather that prevailed from wheat flowering<br />until full maturity of wheat kernel influence on the composition of gluten and wheat<br />processing quality tested,<br />&ndash;determine how environmental factors that are defined by the presence of three<br />different levels of germinate kernels, kernels damaged by wheat bug, kernels infested<br />by Fussarium molds and kernels infested by Alternaria alternata molds affect on the<br />composition of gluten and technological quality of wheat cultivar and<br />&ndash;determine how genetic factors which are defined through differences in HMW-GS<br />on the Glu A1 and Glu D1 locus that cultivars contain or do not contain and identical<br />HMW-GS composition which examined cultivars possess affect on the gluten<br />composition and technological quality of tested wheat varieties.</p><p>The achieved results represent a complex analysis of the impact of various factors on<br />the composition of gluten and technological quality of wheat, which included a<br />enormous database of properites and closely determine how individual microclimatic,<br />genetic and environmental factors influence on the gluten composition and<br />technological quality of wheat.</p>

<p>Promene komponenata i strukture mleka ispitane su tokom fermentacije kori&scaron;ćenjem inokuluma kombuhe kultivisane na crnom čaju zaslađenom saharozom<br />u koncentraciji 10%. Fermentacija mleka sa 2,2% mlečne masti izvr&scaron;ena je na dve različite temperature (37&deg;C i 42&deg;C) i uzorci su analizirani na sledećim pH vrednostima: 6,1; 5,8; 5,4; 5,1; 4,8 i 4,6. Urađena je determinacija i identifikacija produkata fermentacije laktoze kao &scaron;to su: &scaron;ećeri, organske kiseline i masne kiseline. Ispitane su teksturalne i reolo&scaron;ke karakteristike i mikrostruktura uzoraka. Pored toga, utvrđene su sličnosti i razlike uticaja inokuluma kombuhe na proces fermentacije mleka u poređenju sa delovanjem jogurtne, odnosno probiotske starter kulture.<br />Tokom fermentacije mleka u različitim fazama procesa pri odabranim pH vrednostima na 42&deg;C transformi&scaron;e se 14,6% laktoze odnosno 18,2% na 37&deg;C. Sadržaj galaktoze i glukoze koje nastaju fermentacijom i hidrolizom laktoze raste između prve i druge tačke fermentacije (pH=6,07 i pH=5,8). Dominantne organske kiseline tokom fermentacije su L&ndash;mlečna kiselina i sirćetna kiselina. Nije utvrđena značajna razlika u sadržaju masnih kiselina tokom fermentacije mleka kombuhom na 37&deg;C i 42&deg;C. Sadržaj palmitinske kiseline u mleku i uzorcima tokom fermentacije je najveći, zatim slede miristinska, stearinska i oleinska kiselina.<br />Praćenjem procesa fermentacije mleka uz primenu kombuhe na 37&deg;C i 42&deg;C od početne pH vrednosti 6,07 do zavr&scaron;ne 4,6, najznačajnije promene teksturalnih karakteristika (čvrstoće, konzistencije, kohezivnosti i indeksa viskoziteta) i reolo&scaron;kih svojstava zabeležene su između pH=5,4 i 5,1, &scaron;to je u korelaciji sa mikrostrukturom.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Promene viskoziteta u svim uzorcima pokazuju istu regresionu liniju, sa različitim koeficijentima i visokom vredno&scaron;ću r2, osim uzorka proizvedenog primenom jogurtne kulture na pH 5,4. Uzorak dobijen kori&scaron;ćenjem inokuluma kombuhe imao je najveće vrednosti kompleksnog modula, &scaron;to je rezultiralo boljim reolo&scaron;kim karakteristikama gotovog proizvoda.<br />Da bi se definisao empirijski model procesa fermentacije laktoze u mleku delovanjem kombuhe formulisana su prethodno dva matematička modela za kinetiku fermentacije saharoze u tradicionalnom kombuha napitku (na crnom čaju) &ndash; jedan koji opisuje promenu koncentracije saharoze tokom fermentacije, i drugi koji opisuje brzinu fermentacije. Promena koncentracije laktoze na ispitivanim temperaturama 37&deg;C i 42&deg;C sastoji se od dve lag faze između kojih je faza izraženog pada koncentracije. Krive zasićenja pokazuju sigmoidalnu kinetiku na nižim koncentracijama laktoze, ukazujući na kompleksni ne&ndash;Michaelis&ndash;Mentenov tip kinetike.<br />Generalno može se istaći da su primenom inokuluma kombuhe tokom fermentacije mleka u različitim fazama procesa ustanovljene specifične promene komponenata i strukture u poređenju sa efektima delovanja jogurtne odnosno probiotske starter kulture.</p><p>&nbsp;</p> / <p>Changes of milk components and structure were examined during fermentation by kombucha inoculum cultivated on black tea switened with saccharose in a concentration of 10%. The fermentation of milk with 2.2% of milk fat was carried out at two different temperatures (37&deg;C i 42&deg;C) and samples were analyzed at the following pH values: 6.1; 5.8; 5,4; 5.1; 4.8 and 4.6. Determination and identification of the lactose fermentation products, such as: sugars, organic acids and fatty acids were carried out. Textural and rheological characteristics and microstructure of the samples were investigated. Furthermore, the effect of kombucha on the milk fermentation process was compared with the effect of yoghurt and probiotic starter culture.<br />During milk fermentation at various stages of the process 14.6% of lactose content was transformed at 42&deg;C and 18.2% at 37&deg; C. The galactose and glucose content, which are formed by lactose hydrolyses and fermentation, increased between first and second pH point of fermentation (pH = 6.07 and pH = 5.8). Dominant organic acids during fermentation are L&ndash;lactic acid and acetic acid. There is no significant difference between samples in fatty acids content during fermentation on 37&deg;C and 42&deg;C. The level of palmitic acid in milk and samples was the highest of all fatty acids, followed by myristic, stearic, and oleic acid.<br />The most significant changes in textural properties (firmness, consistency, cohesiveness and viscosity index) and viscosity during milk fermentation by kombucha at 37&ordm;C and 42&deg;C, from the initial pH value 6.07 to a final 4.6, were recorded between pH=5.4 and 5.1, which is in correlation with microstructure.<br />Viscosity changes in all samples showed the same regression line with the different coefficients and a rather high r2 except for the sample produced with standard yoghurt culture at the pH 5.4. Samples produced with kombucha had the highest values of the complex modulus, which indicates better rheological characteristics of the final product.<br />In order to define an empirical model of lactose fermentation process in milk by kombucha, two mathematical models (one for the change of saccharose concentration, during its fermentation by kombucha, and the other for the rate of the mentioned fermentation) previously were formulated. Change of lactose concentrations at 37&ordm;C and 42&ordm;C consists of two retaining stages and very steep descend in-between. Saturation curves show a sigmoidal kinetics at low lactose concentrations, indicating a complex non&ndash;Michaelis&ndash;Menten type kinetics.<br />Generally it can be concluded that specific changes in the components and structure of milk by application of kombucha inoculum during fermentation at different stages of the process were established in comparison with the effects of yoghurt and probiotic starter culture.</p>

<p>U ovom radu je obrađen postupak spontane fermentacije tradicionalnog proizvoda, fermentisanog kupusa u glavicama. U prvom delu urađena je karakterizacija domaće tradicionalne populacije Futo&scaron;ki u odnosu na uvozni hibrid Bravo. Na osnovu PCA analize i analize standardnih ocena SS fizičkih, hemijskih i senzorskih paramentara odabrani su uzorci povoljni za proces fermentacije. Proces fermentacje je obavljen na temperaturama 16-18^oC, 18-20^oC i 20-20^oC, i sa razliĉitim koncentracijama soli od 1, 1,5 i 2 %. Analizirani su fizički, hemijski, mikrobiolo&scaron;ki parametri i senzorske osobine kupusa tokom fermentacije. Metodom odzivne povr&scaron;ine sa analizom varijanse (ANOVA) modela odziva za svaki od analiziranih karakteristika i obja&scaron;njeno je koji od parametara procesa temperatura, koncentracija soli i vreme trajanja procesa ima statistiĉki značajan uticaj na formiranje matematiĉkih modela odziva, prikazanih u obliku polinoma drugog reda (SOP). Zaključeno je da Futo&scaron;ki kupus postiţe brţe zavr&scaron;nu taĉku fermentacije u odnosu na hibrid Bravo. Drugi kori&scaron;ćeni tehnolo&scaron;ki postupak u ovom radu je osmotska dehidratacija. Kupus je dehidriran u tri osmotska rastvora (vodeni rastvor natrijum hlorida i saharoze, kombinacija vodenog rastvora natrijum hlorida i saharoze i melase i melasa &scaron;ećerne repe) različitih koncentracija, na tri temperature (20&deg;C, 35&deg;C i 50&deg;C) i pri tri vremena trajanja procesa (1, 3 i 5h). Mereni i računati odzivi procesa osmotske dehidratacije bili su: sadržaj suve materije, gubitak vode, prirast suve materije i indeks efiksanosti procesa. Rezultati ispitivanja pokazuju da povećanje tehnolo&scaron;kih parametara temperature i vremena procesa, kao i koncentracije osmotskih rastvora dovode do intenziviranja prenosa mase u procesu i povećanja vrednosti odzivnih parametara procesa. Takođe, zaključeno je da tokom osmotske dehidratacije u melasi &scaron;ećerne repe dolazi do obogaćivanja kupusa nutritivnim komponentama, naročito kalijumom. Treći segment ovog rada je analiza održivosti osmotski dehidriranog kupusa pakovanog u modiifikovanoj atmosferi dve različite sme&scaron;e gasova N₂ i CO₂. Analizom hemijskih, mikrobiolo&scaron;kih i senzorskih svojstava zaključeno je da ovaj osmotski dehidriran kupus pakovan na navedeni način ima održivost od 90 dana.</p> / <p>This paper describes the process of spontaneous fermentation of traditional product, fermented whole cabbage. In the first part characterization of the local traditional type Futo&scaron;ki cabbage in relation to imported hybrid Bravo was done. Based on the PCA analysis and analysis of the standard score SS physical, chemical and sensory parameters favorable samples for the process of fermentation were selected. The process of fermentation was carried out at three temperatures: 16-18^oC, 18-20^oC and 20-20^oC, and with various concentrations of salt: 1, 1.5 and 2%. The physical, chemical and microbiological parameters, as well as sensory properties of cabbage during fermentation were analyzed. Response surface method with analysis of variance (ANOVA) model response for each of the analyzed characteristics was used and it was explained which of the process parameters (temperature, salt concentration and the duration of the process) had a statistically significant effect on the formation of mathematical models of response, presented in the form of a second order polynomial (SOP). It was concluded that Futo&scaron;ki cabbage faster achieved end point of fermentation as compared to a hybrid Bravo. Another technological method used in this investigation was the osmotic dehydration. Cabbage was dehydrated with three osmotic solutions (an aqueous solution of sodium chloride and sucrose; the combination of an aqueous solution of sodium chloride and sucrose with molasses; sugar beet molasses) of different concentrations, at three temperatures (20&deg;C, 35&deg;C and 50&deg;C) and at three times of the process duration (1, 3, and 5h). The measured and calculated responses of osmotic dehydration process were: dry matter content, water loss, solid gain and the index of efficiency of the process. Test results shown that increase of the technological parameters of temperature and time of process, as well as the concentration of osmotic solutions lead to the intensification of mass transfer in the process and increase values of response parameters of the process. Also, it was concluded that during osmotic dehydration in sugar beet molasses cabbage was enriched with nutritional components, especially potassium. The third segment of this investigation was to analyze the viability of osmotically dehydrated cabbage packaged in modified atmosphere, with two different mixtures of N₂ and CO₂. Analyzing chemical, microbiological and sensory properties it was concluded that the osmotically dehydrated cabbage packaged in this manner has the sustainability of 90 days.</p>

<p>Dosada&scaron;nji objavljeni literaturni podaci ukazuju da aflatoksini, usled njihovog dokazanog toksičnog, mutagenog, teratogenog i kancerogenog efekta na organizam ljudi i životinja, predstavljaju najpoznatiju i najrizičniju grupu mikotoksina. Nasuprot navedenom, dostupna naučna i stručna literatura iz Republike Srbije ukazuje na nedostatak sistematski sprovedenih monitoringa učestalosti pojave aflatoksina. Kao sirovine za ispitivanje pojave aflatoksina, u ovoj doktorskoj disertaciji, odabrani su kukuruz i mleko. Kukuruz je odabran jer predstavlja jednu od najzastupljenijih žitarica u Srbiji. Navedena činjenica dodatno povećava potrebu za istraživanjem, jer pojava aflatoksina u velikoj meri utiče i na kvalitet kukuruza, kao i smanjenje prinosa i ekonomskog profita zemlje. Cilj da se ispita mleko proistekao je iz činjenice da ono usled velike frekventnosti u ishrani, predstavlja namirnicu sa najvećim potencijalnim rizikom za unos aflatoksina u organizam ljudi.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Analiza pojave aflatoksina u kukuruzu obuhvatila je 1000 uzoraka, sakupljenih tokom perioda od četiri godine (2009-2012.). Dobijeni rezultati ukazali su da aflatoksini nisu detektovani u uzorcima kukuruza iz 2009., 2010. i 2011. godine. Međutim, od 700 analiziranih uzoraka kukuruza iz 2012., čak 553 (79%) bilo je kontaminirano aflatoksinima. Značajne razlike u pojavi aflatoksina u kukuruzu, iz različitih proizvodnih godina, mogu se objasniti izuzetno toplim i suvim vremenskim uslovima zabeleženim u 2012. godini. Su&scaron;ni vremenski uslovi bili su povoljni za razvoj plesni i sintezu aflatoksina u kukuruzu, a takođe su u velikoj meri doprineli i visokom nivou pojave aflatoksina M1 (AFM1) u mleku. Analiza 200 uzoraka različitih kategorija kravljeg mleka pokazala je da je AFM1 sa koncentracijama od 0,01 do 1,20 ug/kg detektovan u 198 (98,7%) uzoraka. Na osnovu određenih koncentracija AFM1 u uzorcima mleka, prikupljenih informacija o prosečnom unosu mleka, telesnoj težini različitih starosnih kategorija i polova 1500 ispitanika, procenjen je rizik od unosa AFM1. Dobijeni rezultati ukazali su da su sve ispitane starosne kategorije, a posebno deca, izložena visokom riziku od unosa AFM1 u organizam preko kontaminiranog mleka.<br />Usled svega navedenog, proizilazi potreba za kontinuiranim praćenjem pojave aflatoksina u kukuruzu i AFM1 u mleku, sa ciljem za&scaron;tite stanovni&scaron;tva od rizika povezanih sa njihovim dokazanim toksičnim i kancerogenim efektima. Tokom poslednjih godina, do&scaron;lo je do povećane tražnje za razvojem osetljive, tačne, jednostavne i brze metode, čijom primenom će se obezbediti pouzdano određivanje različitih aflatoksina pri niskim koncentracijama. Usled toga, ELISA metode, kao i metode tečne hromatografije sa različitim detektorima (HPLC-FLD, HPLC-UV light-FLD, LC-MS/MS) su razvijene, optimizovane i validovane. Validacija je izvr&scaron;ena prema smernicama odgovarajućih evropskih Regulativa, analizom sertifikovanih referentnih materijala i spajkovanih uzoraka. Dobijeni parametri validacije potvrdili su da se sve primenjene metode sa visokom pouzdano&scaron;ću mogu koristiti za određivanje aflatoksina u kukuruzu, odnosno AFM1 u mleku. Validovane metode su zatim primenjene za analizu aflatoksina i AFM1 u prirodno kontaminiranim uzorcima kukuruza i mleka. Analizom prirodno kontaminiranih uzoraka kukuruza uočeno je da određena koncentracija aflatoksina u velikoj meri zavisi od neravnomerne raspodele aflatoksina unutar čvrstih uzoraka. Pored toga, analiza uzoraka kukuruza iz skladi&scaron;ta, takođe je ukazala na neravnomernu raspodelu ukupnih plesni, vrste Aspergillus flavus, kao i aflatoksina. S druge strane, dobijeni koeficijenti korelacije (&gt; 0,9) između primenjenih metoda za određivanje AFM1 u mleku, ukazali su da među dobijenim rezultatima postoji snažna korelacija, koja može poticati i od relativno homogenije raspodele AFM1 unutar tečnih uzoraka.</p> / <p>Recent studies have demonstrated that аflatoxins (AFs) represent the best known and most intensively researched mycotoxins in the world, with proven toxic, mutagenic, teratogenic and carcinogenic effects on human and animal health. However, up to the author&#39;s knowledge, there are no investigations concerning the occurrence of AFs in food or feed from Republic of Serbia. For that purpose, maize and cow&acute;s milk samples were chosen as matrixes for investigation. Maize is selected because it represents one of the major crops grown in Serbia and presence of AFs leads to reduction of maize quality as well as significant economical losses. On the other hand, milk has the greatest demonstrated potential for AFs introducing into the human diet since it represents one of the main foodstuffs in human nutrition.<br />An investigation regarding occurrence of AFs in maize included 1000 samples collected during four years period (2009-2012). Obtained results indicate that AFs were not detected in maize samples collected during 2009-2011 period. However, among 700 analyzed maize samples from 2012 even 553 (79%) samples contained AFs. Significant differences in occurrence of AFs in maize could be contributed to extremely hot and dry weather conditions noted during maize growing season 2012. Described weather conditions were favorable for mould growth and AFs synthesis in maize and also could be the possible reason for high contamination frequency of aflatoxin M1 (AFM1) in milk. Analysis of 200 cow&acute;s milk samples showed that AFM1 were detected in 198 (98.7%) samples in concentrations ranged from 0.01 to 1.20 &mu;g/kg. On the basis of the obtained AFM1 concentrations in cow&rsquo;s milk samples, collected information about average milk intake and mean body weight (bw) for different age&rsquo;s categories, mean ingestion of AFM1 in ng/kg per bw per day were estimated. Obtained results showed that all age&rsquo;s categories, especially children, are exposed with high risk related to presence of AFM1 in milk.<br />Based on everything stated above, presence of AFs in maize and AFM1 in milk should be continuously controlled in order to protect the population from risks associated with its proven toxicity and carcinogenicity. During recent years, there has been an increase in demand for development of sensitive, accurate, simple and fast method which is reliable to detect AFs and AFM1 at low concentrations. For that purpose, enzyme linked immunosorbent asssay (ELISA), high performance liquid chromatography with fluorescence detector (HPLC-FLD; HPLC-UV light-FLD) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) were optimized and validated. The method validation was performed according European Union Regulative using certificated reference material as well as spiked blank maize and milk samples. The obtained validation parameters indicate that all applied methods are suitable for determination of AFs in maize as well as AFM1 in milk samples. Afterwards, validated methods were applied for analysis of natural contaminated maize and milk samples. Analysis of natural contaminated maize samples indicate that determined AFs concentration mostly depends of uneven distribution of AFs in solid samples. Furthermore, analysis of maize samples from different warehouses indicates an uneven distribution of moulds, Aspergillus flavus and AFs. On the other hand, obtained correlation coefficients (&gt;0.9) indicate that strong correlation exists between applied methods for AFM1 determination. Relatively homogeneous distribution of AFM1 in liquid samples could be the possible reason for obtained strong correlation between applied methods.</p>

<p>Cilj ove doktorske disertacije je bio da se ispita mogućnost dobijanja prirodnih<br />koagulanata iz zrna pasulja koji bi se koristili u obradi različitih voda i otpadnih voda. U okviru izvedenih eksperimenata su utvrđeni najbolji uslovi za ekstrakciju prirodnih koagulanata iz pasulja, određen je hemijski sastav sirovih ekstrakata dobijenih na različite načine, proverena je trajnost i određen način čuvanja sirovih ekstrakata i ispitan uticaj različitih parametara na koagulacionu aktivnost sirovih ekstrakata.<br />S obzirom na to da su prirodni koagulanti organskog porekla, oni povećavaju sadržaj organskih materija u tretiranoj vodi, pa su u okviru rada ispitane i upoređene različite metode preči&scaron;ćavanja sirovog ekstrakta pasulja, a zatim određen uticaj sirovog ekstrakta i preči&scaron;ćenih koagulanata na sadržaj organskih materija u obrađenoj vodi.<br />Kako bi se ispitala efikasnost prirodnih koagulanata iz zrna pasulja u realnim vodama,<br />oni su bili primenjeni u otpadnim vodama od proizvodnje bioetanola. Pored toga, ispitana je mogućnost njihove primene u kombinaciji sa konvencionalnim koagulantima, i na samom kraju je ispitan sastav pasulja koji preostane nakon ekstrakcije prirodnih koagulanata kako bi se utvrdilo da li je pogodan za kori&scaron;ćenje kao<br />dodatak stočnoj hrani.<br />Dobijeni rezultati su pokazali da se iz zrna pasulja može dobiti ekstrakt visoke koagulacione aktivnosti, koji se dalje može efikasno prečistiti tako da ne povećava sadržaj organskih materija u obrađenoj vodi, već ga naprotiv smanjuje. Takođe, prirodni koagulanti iz pasulja se mogu uspe&scaron;no primeniti za tretman otpadnih voda od proizvodnje bioetanola, mogu biti pomoćni koagulanti aluminijum-sulfatu, a pasulj nakon ekstrakcije prirodnih koagulanata sa destilovanom vodom se može iskoristiti kao<br />dodatak stočnoj hrani.</p> / <p>The aim of this PhD thesis was to investigate the possibility to obtain natural coagulants from common bean which could be used for different waters and wastewaters treatment. The optimal conditions for extraction of natural coagulants from common bean, the chemical composition of crude extracts obtained in different ways and the influence of various parameters on coagulation activity of crude extracts were determined within the performed experiments. The durability of crude extracts was checked and the way of their storage defined.<br />Considering the fact that natural coagulants are of organic origin, they increase the content of organic matter in treated water. Hence, the different methods of purification of common bean crude extract were investigated and compared, and thereafter the influence of crude extract and purified coagulants on organic matter content in treated water was determined.<br />Natural coagulants obtained from common bean were applied in bioethanol stillages in order to explore their efficiency in real waters. Besides, the possibility of their usage combined with conventional coagulants was investigated. At the end, the composition of common bean that remains after extraction of natural coagulants was determined in order to to prove if it was appropriate as addition to feed.<br />Obtained results showed that extract of high coagulation activity can be obtained from common bean. It can be efficiently purified so as not to increase the organic matter content of the water, but on the contrary, to decrease it. Natural coagulants from common bean can be successfully applied for treatment of wastewaters remained after bioethanol production, they can be used as coagulant aid with alum, and the common bean remained after extraction of natural coagulants with distilled water can be utilized as addition to feed.</p>

<p>Cilj ove doktorske disertacije je bio da se oceni mogućnost upotrebe tri sorte domaće &scaron;ljive, različitih epoha sazrevanja (Čačanska rana, Čačanska lepotica i Požegača), kao sirovina za proizvodnju voćnog vina. Utvrđeni mehanički sastav plodova i hemijske karakteristike kljuka i soka ispitivanih sorti &scaron;ljive ukazuju da se čačanska lepotica i Požegača mogu smatrati boljim sirovinama za proizvodnju voćnog vina u odnosu na sortu Čačanska rana. Vr&scaron;ena je optimizacija uslova alkoholne fermentacije (temperature, vrednosti pH, trajanja fermentacije i doze enzimskog preparata), u sklopu koje je, takođe, ispitana i upotreba različitih pektolitičkih enzima za tretman kljuka i ocenjen uticaj upotrebe različitih sojeva kvasaca, kao proizvodnih mikroorganizama, na kvalitet vina od &scaron;ljive. Utvrđeno je da, među ispitanim proizvodnim organizmima, kvasac Spriferm (S. cerevisiae) daje vino od &scaron;ljive najboljeg kvaliteta. Postupkom numeričke optimizacije dobijene su sledeće vrednosti procesnih parametara fermentacije vina od &scaron;ljive: temperatura 25 &deg;C, vrednost pH 3,5 i doza pektolitičkog enzima 0,5 g/100 kg. Pri navedenim uslovima dobijeni fitovani modeli predviđaju prinos etanola od 7,5% v/v, prinos glicerola od 5g/l, prinos vina od 48% (48 ml vina na 100 g kljuka) i formiranje 710 mg/l metanola. Karakterizacija proizvedenog vina od &scaron;ljive podrazumevala je određivanje sadržaja najvažnijih sastojaka: alkohola, kiselina, mineralnih materija, fenolnih i aromatičnih jedinjenja, kao i ocenu njegovih funkcionalnih karakteristika (antiradikalske, antimikrobne i antiproliferativne aktivnosti). Na kraju, ocenjena je mogućnost smanjenja produkcije metanola u vinu od &scaron;ljive primenom različitih fizičko-hemijskih tretmana kljuka. Utvrđena je značajno veća efikasnost postupaka koji uključuju neki vid toplotnog tretmana kljuka u odnosu na postupke koji podrazumevaju upotrebu određenog enolo&scaron;kog sredstva.</p> / <p>The aim of this PhD thesis was to assess the possibility of using three native plum varieties, with different ripening periods (Ĉaĉanska rana, Ĉaĉanska lepotica and Poņegaĉa), as raw material for the production of fruit wines. Determined mechanical composition and chemical characteristics of fruit pomace and juice indicate that the Ĉaĉanska lepotica and Poņegaĉa are considered as better raw materials for the production of fruit wine compared to Ĉaĉanska rana. Optimization of fermentation conditions (temperature, pH, the duration of fermentation and the dose of pectolytic enzyme) was conducted. This step also included investigation of the different pectolytic enzymes use for the treatment of pomace and evaluated the impact of using different yeast strains, as well as the effect of different production microorganisms on the plum wine quality. It was found that, among the tested production microorganisms, Spriferm (S. cerevisiae) yeast gives the plum wine of best quality. Numerical optimization procedure resulted with the following values of the process parameters of plum wine fermentation: temperature 25 &deg;C, pH value 3.5 and pectolytic enzyme dose of 0.5 g/100 kg. Under these conditions the obtained fitted models predict the ethanol yield of 7.5% v/v, glycerol yield 5 g/l, the wine yield of 48% (48 ml from 100 g of pomace) and the formation of 710 mg/l of methanol. Characterization of the produced plum wines included the determination of the most important ingredients: alcohol, acids, minerals, phenolic and aromatic compounds, as well as evaluation of their functional characteristics (antiradical, antimicrobial and antiproliferative activities). Finally, the possibility of reducing the methanol production in plum wine was estimated by applying different physico-chemical treatments of the pomace. Significantly higher efficiency of procedures that involve some form of heat treatment of pomace, compared to treatments which involve the use of certain oenological means, was observed.</p>

<p>Hemometrijskim metodama (deskriptivna statistika, analiza glavnih komponenti, ve&scaron;tačke neuronske mreže i fazi optimizacija) analizirani su rezultati procesa osmotske dehidratacije mesa srebrnog kara&scaron;a, sa ciljem unapređenja efikasnosti osmotskog tretmana i pronalaženja optimalnih tehnolo&scaron;kih parametara.<br />Osmotski tretman se odvijao u tri osmotska rastvora (vodeni rastvor natrijum hlorida i<br />saharoze, kombinacija vodenog rastvora natrijum hlorida i saharoze i melase i melasa &scaron;ećerne repe) različitih koncentracija, na četiri temperature (10&deg;C, 20&deg;C, 35&deg;C i 50&deg;C) i pri tri vremena procesa (1, 3 i 5h). Posmatrani su sledeći odzivi sistema: gubitak vode, prira&scaron;taj suve materije, povećanje sadržaja suve materije, sniženje aktivnosti vode i promena sadržaja minerala (Na, K, Ca i Mg). Karakterizacijom osmotski dehidriranog ribljeg polupoizvoda, poja&scaron;njeni su efekti osmotskog tretmana i inovatinog osmotskog rastvora na senzorne osobine, hemijski i mikrobiolo&scaron;ki profil tretiranog mesa ribe. Rezultati ispitivanja pokazuju da se primenom procesa osmotske dehidratacije povećava gubitak vode, prira&scaron;taj suve materije i sadržaj suve materije u svim uzorcima mesa srebrnog kara&scaron;a. Za sva tri osmotska rastvora, najveće vrednosti dobijene su nakon 5 časova, pri najvi&scaron;im temperaturama i u najvećim koncentracijama rastvora.<br />Povećavanjem temperature procesa, koncentracije rastvora i vremena trajanja procesa, povećan je sadržaj posmatranih minerala u tretiranom mesu ribe. Rezultati<br />ANOVA testa pokazali su da na vrednosti posmatranih odziva statistički značajno utiču<br />sva tri parametra: vreme, temperatura i koncentracija. PCA analizom procesa utvrđeno je da su pri izračunavanju prve glavne komponente najveći uticaj imale vrednosti svih odziva osim aw vrednosti, dok je ona najvi&scaron;e uticala na proračun druge glavne komponente. Iako su modeli ve&scaron;tačkih neuronskih mreža kompleksniji od modela polinoma drugog reda, mreže su pokazale bolji učinak usled visoke<br />nelinearnosti razvijenih sistema. Primenom fazi optimizacije postignute optimalne vrednosti procesnih parametara za vodeni rastvor natrijum hlorida i saharoze su bile na nižim temperaturama i nižim koncentracijama rastvora, dok su za rastvore sa melasom &scaron;ećerne repe optimalne vrednosti na maksimumima posmatranih opsega temperature i koncentracije rastvora. Procesom osmotske dehidratacije smanjen je inicijalni broj bakterija u mesu srebrnog kara&scaron;a. Hemijskim i senzorskim analizama utvrđeno je da je melasa &scaron;ećerne repe zbog svog kompleksnog nutritivnog sastava<br />povoljnije je delovala na promenu hemijskog sastava i senzorne osobine uzoraka u odnosu na druga dva rastvora.</p> / <p>Chemometric methods (descriptive statistics, principal components analysis, artificial neural networks and fuzzy optimization) were used to analyze the results of osmotic dehydration of silver crucian carp, with the aim of improving the efficiency of the osmotic treatment and finding the optimal technological parameters.<br />The osmotic treatment was carried out in three osmotic solution (aqueous sodium chloride and sucrose solution, sugar beet molasses and the combination of these two solutions) of varying concentrations, at four temperatures (10&deg;C, 20&deg;C, 35&deg;C and 50&deg;C) and at three processing times (1, 3 and 5 h). The observed system responses were: water loss, solid gain, increase in dry matter content, reduction of water activity<br />and changes in mineral content (Na, K, Ca and Mg). The characterization of dehydrated fish, explained the effects of osmotic treatment on its sensory properties, chemical and microbiological profile. Results have shown that the application of osmotic dehydration increases water loss, solid gain and dry matter content in all samples of fish meat. For all three osmotic solution, the highest values were obtained after 5h, at the highest temperatures and in the highest concentration of the solution. By increasing the process temperature, concentration and time, increased the mineral content in the fish meat. The results of the ANOVA test have shown that the values of the observed responses significantly affect all three parameters: time, temperature and concentration. PCA analysis process has found that on calculation of the first principal component all response values except aw value had the greatest impact, while aw value had the most influence on the calculation of the other major component. Although models of artificial neural network models are more complex than second order polynomial, the network showed better performance due to the high nonlinearity of the developed system. Application of fuzzy optimization obtained optimal values of the process parameters for aqueous solution of sodium chloride and sucrose were at lower temperatures and lower concentrations of the solution, while the solutions with molasses optimal values of the maxima observed ranges<br />of temperature and solution concentration. The process of osmotic dehydration has reduced the initial number of bacteria in meat silver carp. Chemical and sensory analyzes have shown that the sugar beet molasses due to its complex nutritional composition has a better effect on changing the chemical composition and sensory characteristics of the samples.</p>

<p>Poznavanje i razumevanje adhezivne sposobnosti i formiranja biofilma patogenih bakterija, kao i njihovog odnosa prema faktorima koji mogu stimulisati ili inhibirati razvoj biofilma, je od fundamentalnog značaja za iznalaženje mera za njihovu efikasnu prevenciju i eliminaciju.<br />Imajući u vidu navedenu činjenicu kao i da je Salmonella enterica serotip Enteritidis epidemiolo&scaron;ki najfrekventniji serotip cilj ovog istraživanja je bio da se ispita: sposobnost različitih sojeva Salmonella Enteritidis izolovanih iz kliničkog materijala, hrane za životinje i odabranog referentnog soja da formiraju biofilm, adherentnost na povr&scaron;ine od stakla i nerđajućeg čelika, sposobnost preživljavanja odabranih biofilm produkujućih sojeva kao i mogućnost primene konfokalne laserske i skening elektronske mikroskopije u vizuelizaciji trodimenzionalne strukture biofilma.<br />Određivanjem morfotipa kolonija na Kongo red agaru na temperaturi inkubiranja od 25&deg;C među testiranim izolatima detektovana su tri morfotipa RDAR (red, dry and rough), BDAR (brown dry and rough) i SAW (smooth and white). Polovina testiranih izolata je eksprimirala RDAR morfotip. Izolati koji su eksprimirali karakterističan morfotip na ovoj temperaturi su formirali na vazduh tečnost međufazi isti tip pelikule.<br />Uporednom analizom rezultata primenjenih skrining testova za utvrđivanje sposobnosti formiranja biofilma pri temperaturi inkubiranja od 25&deg;C ustanovljena je korelacija između pojave određenog morfotipa na Kongo crvenom agaru i sposobnosti formiranja biofilma u kristal violet i pelikula testu. Međutim, sa povećanjem temperature inkubiranja na 37oC, ova korelacija nije ustanovljena, sa izuzetkom izolata SE8.<br />Svi testirani izolati su pokazali sposobnost adherencije na povr&scaron;inu stakla i nerđajućeg čelika, ali u različitoj meri. Na sposobnost adherencije povoljniji uticaj je imala temperatura inkubiranja od 25&deg;C (p&lt;0,05), sa izuzetkom izolata SE3 (p&gt;0,05). Između stepena adherencije izolata na povr&scaron;ine stakla i nerđajućeg čelika nisu ustanovljene statistički značajne razlike (p&gt;0,05).<br />Praćenjem stope preživljavanja tokom 28 dana u uslovima isu&scaron;ivanja evidentirana je znatno veća stopa preživljavanja ćelija izolata RDAR morfotipa u odnosu na stopu preživljavanja ćelija BDAR morfotipa (p&lt;0,05). Praćenjem stope preživljavanja tokom 90 dana u uslovima povremene dostupnosti hranljivih materija, zabeležena je veća stopa preživljavanja u odnosu na stopu preživljavanja u uslovima isu&scaron;ivanja. U uslovima povremene dostupnosti hranljivih materija nakon devedeset dana ispitivanja kod obe grupe izolata procenat vijabilnih ćelija je iznosio vi&scaron;e od 50%.<br />Primenjenim mikroskopskim tehnikama (CLSM i SEM) omogućena je detaljna vizualizacija formiranih biofilmova. Na modelu izolata SERDAR morfotipa, ustanovljeno je da se formiranje biofilma pod primenjenim eksperimentalnim uslovima, odvija u tri faze: 1) inicijalna adhezija za povr&scaron;inu i formiranje manjih ćelijskih agregata (24h); 2) formiranje većih ćelijskih agregata uz produkciju EPS (48h); 3) sazrevanje biofilma uz značajnu produkciju EPS &scaron;to omogućava formiranje stabilne trodimenzionalne strukture biofilma (96h).<br />Nasuprot karakteristikama koje bakterije pokazuju tokom rasta u medijumima koji obiluju hranljivim materijama, bakterije u biofilmovima pokazuju drugačije osobine u pogledu ekspresije gena i karakteristika rasta. Zahvaljujući ovim razlikama, bakterije u biofilmovima pokazuju povećanu rezistenciju na antibiotike i dezinficijense, zbog čega se konstantno razvijaju nove kontrolne strategije u cilju iznalaženja potencijalnih biolo&scaron;kih re&scaron;enja koja pored različitih enzima, faga, antimikrobnih jedinjenja proizvedenih od strane mikroorganizama uključuju i antimkrobna jedinjenja biljnog porekla kao &scaron;to su biljni ekstrakti, etarska ulja i različiti začini. Stoga, je u okviru drugog segmenta ovog istraživanja ispitivan hemijski sastav etarskih ulja, antimikrobni efekat etarskih ulja (O. heracleoticum , O. vulgare , Th. vulgaris i Th. serpyllum) i pojedinačnih komponenti etarskog ulja (karvakrola i timola) na bujonske kulture testiranih sojeva Salmonella Enteritidis kao i uticaj odabranih koncentracija etarskih ulja na inicijalnu adheziju i već formirani biofilm odabranih sojeva Salmonella Enteritidis.<br />Etarska ulja je karakterisao visok zbirni udeo glavnih fenolnih komponenti karvakrola i timola: O. heracleoticum (71,6%), O. vulgare (63,6%), Th. vulgaris (59,77%), Th. serpyllum (40,04%). Etarska ulja su ispoljila antimikrobni efekat sledećim redosledom: O. heracleoticum &gt;O. vugare =Th. vulgaris &gt;Th. serpyllum. Antimikrobni efekat etarskih ulja je bio direktno srazmeran zbiru fenolnih komponenti (karvakrola i timola) u etarskom ulju. U odgovoru na tretman etarskim uljima između izolata S. Enteritidis nisu ustanovljene razlike.<br />Etarska ulja, karvakrol i timol su pokazali inhibitorni efekat na inicijalnu adheziju i posledično na formiranje biofilma testiranih izolata S. Enteritidis na dozno zavisan način. Upoređivanjem uticaja etarskih ulja na inhibiciju inicijalne adhezije i metabolitičke aktivnosti ćelija između izolata RDAR i BDAR morfotipa ustanovljene razlike nisu bile statistički značajne (p&gt;0,05).<br />Ispitivanjem uticaja etarskih ulja, karvakrola i timola na ukupnu biomasu biofilma i metabolitičku aktivnost ćelija dokazano je da etarska ulja u primenjenim koncentracijama ispoljavaju uticaj na redukciju ukupne biomase formiranog biofilma i metaboličke aktivnosti bakterijskih ćelija na dozno zavisan način u funkciji vremena. Znatno veća efikasnost primenjenih tretmana je pokazana u slučaju njihove primene na biofilmove formirane od strane izolata BDAR morfotipa (p&lt;0,05).</p> / <p><span style="font-size:10px;">Knowledge and understanding ability of the pathogenic bacteria that adhere to surface and form biofilm, as well as their relationship between these abilities and factors that stimulate or inhibit biofilm development, are essential to develop strategies for their prevention and elimination.<br />Considering also the fact that Salmonella enterica serotype Enteritidis has been epidemiologically the most frequently found serotype, the aims of this study were to evaluate: biofilm forming ability of several Salmonella Enteritidis strains isolated from clinical material, feed and selected control strain, their ability to adhere to glass and stainless steel surfaces, survival of selected biofilm-producing strains, as well as the possibility of applying confocal laser scanning (CLSM) and scanning electron microscopy (SEM) for visualization of biofilm three-dimensional structure.<br />Determination of colony morphotype on Congo red agar at incubation temperature of 25&deg;C revealed that among all tested isolates three morphotypes were detected: RDAR (red, dry and rough), BDAR (brown dry and rough) and SAW (smooth and white). Half of all tested isolates expressed RDAR morphotype. All isolates that expressed specific morphotype at this incubation temperature also formed the corresponding type of pellicle at air-liquid interface.<br />Comparing the results of the applied assays was ascertained the correlation between specific morphotype on Congo red agar and biofilm forming ability in Cristal violet and pellicle tests, at incubation temperature of 25&ordm;C. In the case of assays conducted at 37&deg;C, this correlation was not established, except for the isolate SE8.<br />All tested isolates showed varying degree of the ability to adhere to glass and stainless steel surfaces. Incubation temperature of 25&ordm;C had more favorable effect on the adherence, with the exception of isolate SE3 (p&gt;0.05). There were no statistically significant differences between adherence ability of all isolates to glass and stainless steel surfaces (p&gt;0.05).<br />Accompaniment of the survival rate during 28 days in the conditions of desiccation, the significantly higher survival rate was</span> <span style="font-size:10px;">obtained for RDAR than BDAR morphotype isolates (p&lt;0.05). Accompaniment of the survival rate during 90 days in the conditions of occasional availability of nutrients, it was detected the higher survival rate than in condition of desiccation. Under these conditions, after 90 days, there were more than 50% of viable cells among both groups of isolates.<br />Applied microscopic techniques (CLSM and SEM) provided detailed visualization of formed biofilms. On model of SERDAR morphotype isolate, it was established that biofilm formation under this experimental conditions has three phases: 1) initial adhesion to the surface and formation of small cell aggregates (24h); 2) formation of large cell aggregates followed with production of extracellular polymer substance (EPS) (48h); 3) maturation of biofilm followed with significant EPS production, which allows formation of stabile three dimensional structure of the biofilm (96h).<br />Contrary to characteristics that bacteria expressed during their growth in the nutrient media, bacteria in biofilms show different properties in terms of genes expression and growth characteristics. Due to these differences, bacteria in biofilms showed higher resistance to antibiotics and disinfectants. For these reasons are being constantly developed new potential biological control strategies that aim at finding the potential biological solutions that besides different enzymes, phages, antimicrobial compounds produced by microorganisms, also include antimicrobial compounds of plant origin, such as extracts, essential oils and different spices.<br />Therefore, the other segment of this research was investigation of the chemical composition and antimicrobial properties of different essential oils (O. heracleoticum, O. vulgare, Th. vulgaris and Th. serpyllum) and their components (carvacrol and thymol), against broth cultures of Salmonella Enteritidis. Also, selected concentrations of essential oils were tested against initial adhesion and preformed biofilm of selected Salmonella Enteritidis isolates.<br />Essential oils were characterized by high amount of phenol compounds carvacrol and thymol: O. heracleoticum (71.6%), O. vulgare (63.6%), Th. vulgaris (59.77%) and Th. serpyllum (40.04%). Essential oils showed antimicrobial potential as follows: O. heracleoticum &gt; O. vugare = Th. vulgaris &gt; Th. serpyllum. Antimicrobial effect was directly proportional to the total content of phenolic components (carvacrol and thymol) in essential oil. Between responses of different S. Enteritidis isolates to essential oil treatment, there was no significant difference.<br />Essential oils, carvacrol and thymol demonstrated inhibitory effect on initial adhesion and consequently, on biofilm formation of S. Enteritidis isolates, in a dose-dependent manner. Comparing influence of essential oil on the inhibition of initial cell adhesion and metabolic activity of cells RDAR and BDAR morphotype, no statistically significant differences were established (p&gt;0.05).<br />Examination of the influence of essential oils, carvacrol and thymol on total biomass of preformed biofilms and metabolic activity of cells, it was revealed that essential oils in applied concentrations cause reduction of total biomass of preformed biofilm and metabolic activity</span> <span style="font-size:10px;">of bacterial cells in a time and dose dependent manner. Applied treatments demonstrated significantly higher efficiency on BDAR morphotype biofilms (p&lt;0.05).</span></p>