<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>

<p>Poli(mlečna kiselina) (PLA) predstavlja jedan od najpopularnijih komercijalnih biorazgradivih polimera. Iako može da zameni neke od najče&scaron;će kori&scaron;ćenih sintetskih polimera, neka njegova svojstva (lo&scaron;a barijerna, termička i mehanička) jo&scaron; uvek predstavljaju prepreku u &scaron;iroj primeni, posebno za pakovanje hrane. Jedan od najsavremenijih načina prevazilaženja nedostataka u svojstvima biopolimera predstavljaju nanotehnologije.<br />U ovom radu ispitan je uticaj dodatka različitih koncentracija hidrofobnih nanočestica silicijum (IV) oksida (od 0.2 mas.% do 5 mas.%) pripremom uzoraka u rastvoru, i rastopu na toplotna, mehanička, i barijerna svojstva PLA. Morfolo&scaron;ke karakteristike uzoraka nanokompozita snimljene su pomoću skenirajuće elektronske mikroskopije (SEM). Ostvarena je izuzetno dobra disperzija i distribucija hidrofobnih čestica silicijum (IV) oksida koje su u malim udelima dodavane u poli(mlečnu kiselinu). Dobra disperzija i distribucija hidrofobnih čestica silicijum (IV) oksida ostvarena je kako pripremom nanokompozita metodom u rastvoru, tako i metodom u rastopu.<br />Toplotna svojstva PLA i pripremljenih nanokompozita proučavana su primenom diferencijalnog skenirajućeg kalorimetra (DSC), dok je stepen kristalnosti određen rasipanjem X zraka pod &scaron;irokim uglom(WAXD). Mehanička svojstva su ispitivana da bi se odredio uticaj dodatka nanočestica SiO2 na prekidnu čvrstoću i izduženje čistog PLA. Iako su prilikom pripreme materijala metodom u rastvoru, pobolj&scaron;anja mehaničkih i barijernih svojstava postignuta pri udelima silicijum (IV) oksida u rasponu od 0,2 do 5 mas.%, najznačajnija pobolj&scaron;anja postignuta su za najmanje udele nanočestica (0,2 mas.% i 0,5 mas.%). Pobolj&scaron;anja mehaničkih i barijernih svojstava nanokompozita, primenjenih metodom u rastopu, su registrovana i za udele silicijum (IV) oksida od 0,2 do 3 mas.%.<br />Takođe je ispitana mogućnost primene pripremljenog nanokompozita na osnovu poli(mlečne kiseline) i silicijum (IV) oksida za pakovanje prehrambenih proizvoda na primeru pakovanja svežeg svinjskog mesa (M. longissimus thoracis et lumborum). Ispitivanjem uticaja materijala za pakovanje svežeg mesa u vakuumu, na parametre tehnolo&scaron;kog (pH, boja), senzorskog, i mikrobiolo&scaron;kog kvaliteta mesa, utvrđeno je da su PLA kao i nanokompoziti na osnovu PLA sa različitim udelima silicijum (IV) oksida, pogodni za vakuum pakovanje i skladi&scaron;tenje svežeg svinjskog mesa.</p> / <p>Poly(lactic acid) presents one of the most popular bio-polymers for diverse applications. However, the use of PLA as food packaging material is limited due to poor barrier and mechanical properties. These properties could be improved by incorporation of nanoparticles into polymer matrix.<br />In this work neat PLA films and PLA films with different percentage of hydrophobic fumed silica nanoparticles (0,2 wt.% to 5 wt.%) were prepared by solution casting and melt blending methods. Several procedures were used to characterize the influence of different silica content on dispersion (SEM), crystalline behavior (WAXD), thermal stability (DSC, TGA), mechanical and barrier properties. It is shown that the applied techniques and selection of specific hydrophobic spherical nanofiller provide a good dispersion and distribution of silica nanoparticles in poly(lactic acid) for both film preparation methods.<br />Characteristics of films prepared by solution casting method showed improvements in mechanical and barrier properties for all loadings of nanofiller but the most significant improvements were achieved for lowest silica content (0,2 wt.% and 0,5 wt.%) The improvements in material characteristics (mechanical and barrier) for melt blending method were also achieved (for concentrations from 0,2 wt.% to 3 wt.%).<br />After film preparation, selected cuts of M. longissimus thoracis et lumborum were packed in prepred films of polymer nanocomposites, and the shelf-life characterisation was conducted on technological, sensory and microbiological paramethers of quality. After shelf-life characterisation it can be concluded that polymer nanocomposites based on PLA and silica nanoparticles could be used for packaging od fresh pork meat in vacuum.</p>

<p>Predmet doktorske disertacije je razvoj aktivnog jestivog omotača na bazi hitozana sa dodatkom etarskih ulja začinskog bilja i pčelinjeg voska, kao i njegova aplikacija u cilju produženja održivosti suve fermentisane Petrovačke kobasice.<br />U cilju realizacije programa teze, formirane su tri osnovne grupe filmova: hitozan-etarsko ulje origana, hitozan-etarsko ulje kima i hitozan-etarsko ulje kima-pčelinji vosak. Paralelno sa pripremom filmova, proizvedeni su i odgovarajući kolagen-hitozan laminirani omotači. U pripremi filmova i omotača su primenjena dva vlažna postupka. Filmovi su dobijeni razlivanjem, a laminirani omotači premazivanjem filmogene emulzije preko kolagenog omotača. Tokom razvijanja, ispitivan je uticaj različitih parametara na svojstva dobijenih filmova: viskozitet i koncentracija hitozana, dodatak polietilenoksida kao kopolimera u film, dodatak različite koncentracije etarskog ulja, uslovi me&scaron;anja i temperature, kao i dodatak različite koncentracije pčelinjeg voska.<br />Dobijeni filmovi i omotači su okarakterisani ispitivanjem osobina značajnih za primenu materijala, a to su fizičko-mehanička (debljina, zatezna jačina i izduženje pri kidanju), strukturna (ATR-FTIR spektrometrija i elektron skenirajuća mikroskopija), fizičko-hemijska (sadržaj vlage, bubrenje, rastvaranje), barijerna (propustljivost gasova i brzina propustljivosti vodene pare) svojstva i biolo&scaron;ka aktivnost (antioksidatino i antimikrobno delovanje). Na osnovu detaljne karakterizacije, odabrani su filmovi i omotači optimalnih svojstava za primenu u za&scaron;titi Petrovačke kobasice tokom skladi&scaron;tenja.<br />Ispitano je dejstvo premaza na očuvanje kobasice sa i bez dodate komercijalne i autohtone starter kulture. Efekat primene premaza izučavan je ispitivanjima parametara kvaliteta Petrovačke kobasice i to, praćenjem promene sadržaja vlage, pH vrednosti, boje, oksidacije lipida, kao i senzorne ocene mirisa i ukusa ove kobasice tokom skladi&scaron;tenja.<br />Na osnovu prikazanih rezultata, može se zaključiti da je sintetisan aktivan jestivi premaz na bazi hitozana optimizovanih barijernih, fizičko-hemijskih, antioksidativnih i antimikrobnih svojstava. Sintetisani premaz ima manju brzinu propustljivosti vodene pare, uz očuvanu nisku propustljivost za gasove, smanjenu osetljivost na delovanje vlage i izraženiju antimikrobnu i antioksidativnu aktivnost. Upkos optimizovanim barijernim svojstvima za vodenu paru, hitozanski premaz sa dodatkom etarskih ulja i/ili pčelinjeg voska nije imao efekta u očuvanju sadržaja vlage suve fermentisane kobasice tokom skladi&scaron;tenja. Ispitivani premazi su doprineli očuvanju boje preseka kobasice, ali ovaj efekat nije bio potpuno izražen kod svih tipova kobasice i svih premaza. Sva tri parametra za praćenje oksidativnih promena u kobasici ukazuju na to da je nano&scaron;enjem hitozanskog premaza sa etarskim uljem origana ili kima i pčelinjim voskom, kobasica efikasno za&scaron;tićena od nepoželjnih oksidativnih promena. Između eksperimenata se može povući paralela, da hitozanski premaz pokazuje za&scaron;titni efekat prema senzornom profilu mirisa i ukusa, do blizu 5 meseci skladi&scaron;tenja. Na ovom nivou razvoja premaza, on se može preporučiti kao pomoćan ambalažni materijal.</p> / <p>The subject of the doctoral dissertation is development of active edible coating based on chitosan with added herb essential oils and beeswax, as well as its application for dry fermented sausage shelf life extension.<br />In order to realize the program of investigation, three basic groups of films were produced: chitosan-essential oil of oregano, chitosan-essential oil of caraway and chitosan-essential oil of caraway-beeswax. Simultaneously with the production of films, collagen-chitosan laminated casings were produced. In the production of films and laminated casings, two wet methods were applied. Films were produced by casting method, while laminated casings were produced by coating collagen casing with filmogenic emulsion. During production, the influence of different parameters on properties of produced films and casings was investigated: viscosity and concentration of chitosan, addition of poly (ethylene oxide) as copolymer in the films, addition of different concentration of essential oils, mixing and temperature conditions, as well as addition of different concentration of beeswax.<br />Produced films and laminated casings were characterized by the investigation of properties that are important for material application, namely physical-mechanical (thickness, tensile strength and elongation at break), structural (ATR-FTIR spectrometry and scanning electron microscopy), physical-chemical (water content, swelling, solubility), barrier (gas permeability and water vapor transmission rate) properties and biological activity (antioxidative and antimicrobial activity). Based on detail characterization, films and casings with optimal properties were selected for application on Petrovac sausage with and without the addition af commercial or indigenous starter culture for preservation during storage.<br />The effect of coating application was analyzed based on the quality parameters of Petrovac sausage, namely: water content, pH value, color, lipid oxidation and sensory profile of taste and odor of the sausage during storage.<br />Based on presented results, it can be concluded that active edible coating based on chitosan was synthesized, with optimized barrier, physical-chemical, antioxidant and antibacterial properties. Synthesized coating has lower water transmission rate with preserved low gas permeability, lowered sensibility to humidity and more pronounced antimicrobial and antioxidant activity. Despite optimized water vapor barrier properties, chitosan coating with addition of essential oils and/or beeswax did not show the effect in preserving the water content in the sausage during storage. Investigated coatings contributed to the preservation of core color of the sausage, but this effect was not fully expressed in all types of sausages and coatings. All three parameters for investigation of oxidative changes in the sausage showed that chitosan coating with essential oils of oregano and caraway and beeswax efficiently preserved sausage from unwanted oxidative changes. Mutual conclusion from the experiments is that chitosan coating shows preservative effect on the sensory profile of taste and odor till approximately 5 months of storage. On this level of coating development, it can be recommended as auxiliary packaging material.</p>

<p>Proizvodnja fermentisanih mliječnih napitaka unapreijeđenih funkcionalnih karakteristika postala je jedan od glavnih fokusa u industriji prerade mlijeka. Cilj doktorske disertacije je ispitivanje biolo&scaron;ke aktivnosti fermentisanih mliječnih napitaka dobijenih primjenom nekonvencionalne starter kulture, kombuhe (kultivisane na crnom čaju zaslađenim saharozom u koncentraciji od 10%) i poređenje sa karakteristikma proizvoda dobijenih primenom konvencionalnih starter kultura, jogurtne odnosno probiotske, tokom skladi&scaron;tenja. Za fermentaciju je kori&scaron;ćeno mlijeko sa 2,8% mliječne masti na temperatura 42&deg;C.<br />Promjene tokom fermentacije mlijeka primjenom kombuhe i konvencionalnih starter kultura praćene su određivanjem stepena proteolize, sadržaja laktoze, D&ndash; galaktoze, D&ndash;glukoze i D&ndash;fruktoze i masnih kiselina pri sledećim pH vrijednostima: 6,4; 6,0; 5,5; 5,0 i 4,6. Promjene antihipertenzivne aktivnosti (AKE inhibitorna aktivnost), antioksidativne aktivnosti (ABTS i DPPH metod) kao i promjene stepena proteolize, reolo&scaron;kih i senzornih karakteristika sve tri vrste fermentisanih mliječnih napitaka praćene su tokom 21-og dana skladi&scaron;tenja. Osim toga praćene su i promjene sadržaja &scaron;ećera, masnih kiselina, minerala (kalcijuma, natrijuma i kalijuma), vitamina C i biogenih amina.<br />Tokom procesa fermentacije mlijeka primjenom različitih starter kultura može se zaključiti da postoji razlika u promjenama udijela pojedinačnih proteinskih frakcija analiziranih metodom kapilarne elektroforeze.<br />Različite starter kulture utiču na različitu AKE inhibitornu aktivnost tokom skladi&scaron;tenja, &scaron;to ukazuje na različitu proteolitičku aktivnost kori&scaron;ćenih starter kultura. Utvrđeno je da AKE inhibitorna aktivnost raste tokom skladi&scaron;tenja, pri čemu uzorci proizvedeni primjenom kombuhe imaju najveću AKE inhibitornu aktivnost na kraju 14 dana skladi&scaron;tenja i ona iznosi 79,4%, dok su u jogurtu i probiotskom jogurtu te vrijednsoti 63,4 i 64,6% redom. Takođe, tokom skladi&scaron;tenja stepen proteolize raste u svim uzorcima sa značajnim međusobnim varijacijama. Antiksidativna aktivnost svih uzoraka opada tokom skladi&scaron;tenja ali je u svim uzorcima zabilježena veća aktivnost na ABTS nego na DPPH slobodne radikale. Nakon 21-og dana skladi&scaron;tenja najveći antioksidativni potencijal određen metodom stabilizacije ABTS.+ katjona imali su uzorci sa jogurtnom starter kulturom (TEAC vrijednost 8,922 mmolmg-1). U pogledu sastava masnih kiselina, tokom 14 dana skladi&scaron;tenja u kombuha fermentisanim mliječnim napicima<br />kao i napicima dobijenim sa jogurtnom i probiotskom starter kulturom dolazi do porasta udjela zasićenih (SFA) i opadanje mononezasićenih (MUFA) i polinezasićenih masnih kiselina (PUFA). Nakon 21-og dana skladi&scaron;tenja sadržaj SFA; MUFA i PUFA u kombuha fermentisanom mliječnom napitku iznosio je 65,94; 30,73 i 3,33% redom, dok su te vrijednosti kod jogurta iznosile 66,02; 30,77 i 3,21% i probiotskog jogurta 66,04; 30,66 i 3,30 % redom. Najveći sadržaj vitamina C nakon proizvodnje i 14 dana skladi&scaron;tenja imali su uzorci sa kombuha starter kulturom (0,5457 &plusmn; 0,017 mg100g-1). Uzorci dobijeni upotrebom konvencionalnih startera pokazali su bolje reolo&scaron;ke osobine pri ispitivanim uslovima tokom 21 dana skladi&scaron;tenja. Kombuha fermentisani mlečni proizvod imao je karakterističan, blago kiseli, osvežavajući ukus i nagla&scaron;enu aromu.<br />Na osnovu dobijenih rezultata biolo&scaron;ke aktivnosti i promjena kvaliteta kombuha fermentisanog mliječnog napitka tokom skladi&scaron;tenja, u odnosu na karakteristike proizvoda dobijenih upotrebom konvencionalnih starter kultura može se objasniti opravdanost upotrebe kombuha starter kulture u fermentaciji mlijeka sa ciljem dobijanja novog funkcionalnog fermentisanog mliječnog proizvoda.</p> / <p><span style="font-size:11px;">Nowadays, production of fermented dairy products with elevated benefits on human health has become one of the major focuse in dairy industry. The aim of the PhD thesis is to examine the biological activity of fermented milk products obtained using non-conventional starter culture kombucha (cultivated on black tea with 10% of sucrose) and comparision with products obtained by conventional starter cultures, probiotic/yoghurt during storage. Milk with 2.8% of milk fat was used for the samples production at temperature of 42 &deg;C.<br />The changes of components content during the milk fermentation by kombucha and conventional starter cultures were monitored at the following pH values: 6.4; 6.0; 5.5; 5.0 and 4.6., by determining the degree of proteolysis, lactose, D-galactose, D-glucose and D-fructose, fatty acids. The antihypertensive activity (ACE inhibitory activity), antioxidant activity (ABTS and DPPH tests) and the degree of proteolysis, sensory and rheological characteristics of all three types of fermented milk products were observed during 21 days of storage. Moreover, the chemical qualities of samples were monitored analyzing the contents of sugars, fatty acids, minerals (calcium, sodium and potassium), vitamin C and biogenic amines.&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; There were differences in protein fractions (analyzed by capillary electrophoresis) of products obtained by using different starter cultures during the milk fermentation. Different starter cultures affect different ACE inhibitory activity during the storage, which implies different proteolytic activity of used starter cultures. It has been found that the ACE inhibitory activity was increased during the storage; wherein the samples obtained using kombucha starter culture have the highest ACE inhibitory activity at the 14th day of storage, 79,4%, while in yogurt and probiotic yoghurt it was 63.4 and 64.6% respectively. Also, the degree of proteolysis during the storage was increased in all samples with significant mutual variations. In all products, higher ABTS than 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was determined, while both activities slightly decreased during the storage. The antioxidant activity of all samples decreases during storage. After 21 days of storage, the highest antioxidant potential, determined by the ABTS. + method had a yoghurt samples (TEAC value of 8.922 mmolmg-1). In terms of the fatty acids composition during 14 days of storage in all type of fermented dairy products relative content of SFA (saturated fatty acids - SFA) increased, while relative contents of MUFA (monounsaturated fatty acids) and PUFA (polyunsaturated fatty acids) decreased during that period of storage. After 21 days of storage the content of SFA; MUFA and PUFA in kombucha fermented milk product was 65.94; 30.73 and 3.33% respectively. In yogurt sample their content was 66.02, 30.77 and 3.21%, while in probiotic 66.04; 30.66 and 3.30% respectively. In all fermented milk products, long chain fatty acids were dominant with a total share of about 45% in all varieties of fermented dairy products. The highest content of vitamin C after production and 14 days of storage was in samples obtained by kombucha starter culture (0.5457 &plusmn; 0.017 mg100g-1). Samples obtained by conventional starter showed better overall rheological properties at the tested conditions for 21 days of storage. Kombucha fermented milk product had a characteristic, distinctive mild sour, refreshing taste and conspicuous aroma.<br />The obtained results of biological activity and the quality of kombucha fermented milk products during storage in comparison to the same characteristics of the products obtained using conventional starter culture, could explain that kombucha is convenient starter for milk fermentation with the aim of obtaining new functional fermented milk products with pronounced bioactive characteristics and distinctive sensory and rheology properties.</span></p>

<p>U savremenom uzgoju živine i svinja sme&scaron;e se retko koriste u pra&scaron;kastom obliku<br />već se uglavnom peletiraju nakon ume&scaron;avanja pojedinačnih sastojaka. Pri<br />peletiranju dolazi do naru&scaron;avanja granulacije sme&scaron;e, odnosno do gotovo<br />potpunog eliminisanja krupnih čestica, kao i do nastajanja velike količine najsitnijih čestica. U okviru istraživanja u ovoj doktorskoj disertaciji ispitivan je uticaj promene odabranih parametara mlevenja i peletiranja na granulaciju čestica od kojih su pelete sačinjene. Cilj je bio da se utvrdi kombinacija parametara koja doprinosi povećanju sadržaja krupnih čestica, &scaron;to je značajno u ishrani živine, odnosno da se utvrdi kombinacija parametara koja će u &scaron;to većoj meri uvećati sadržaj čestica srednje veličine i umanjiti udeo najsitnijih čestica, &scaron;to je značajno u ishrani svinja. Pri tome je određivan i kvalitet peleta, koji ne sme biti značajnije naru&scaron;en, kao i potro&scaron;nja energije pelet prese za koju je poželjno da je &scaron;to niža.<br />Nezavisni parametri peletiranja bili su granulacija kukuruznog mliva, rastojanje (zazor) između valjaka i matrice pelet prese, debljina matrice pelet prese i sadržaj vode materijala koji se vodi na peletiranje. Istraživanje je podeljeno u dve faze, gde je u prvoj za usitnjavanje primenjen mlin čekićar, a u drugoj mlin sa valjcima. Na oba uređaja prizvedene su po tri granulacije mliva, pri čemu se granulacija ukrupnjava od najsitnijeg mliva dobijenog na mlinu čekićaru do najkrupnijeg mliva dobijenog na mlinu sa valjcima. U prvoj fazi tri granulacije mliva dobijene na mlinu čekićaru su peletirane u kombinaciji sa tri zazora valjci-matrica (0,30; 1,15 i 2,00 mm) i tri sadržaja vode materijala (14,5%, 16,0% i 17,5%), a u drugoj fazi tri granulacije mliva dobijene na mlinu sa valjcima peletirane su u kombinaciji sa tri debljine matrice (24, 30 i 36 mm) i tri sadržaja vode materijala (14,5%, 16,0% i 17,5%). Dakle, u obe faze su varirana tri parametra na tri nivoa pri čemu je primenjen Box-Behnken eksperimentalni dizajn. Zavisno promenljive karakteristike (odzivi) bili su temperatura matrice pelet prese, specifična potro&scaron;nja energije pelet prese, udeo pra&scaron;ine u peletama, stepen želatinizacije skroba, tvrdoća, stepen otiranja i nasipna masa peleta, kao i granulacija materijala nakon peletiranja. Za svaki od pomenutih odziva definisan je polinom (model) drugog reda. Dobijeni modeli upotrebljeni su za optimizaciju procesa peletiranja sa ciljem da se postigne željena granulacija peletiranog materijala, uz &scaron;to bolji kvalitet peleta i uz &scaron;to manju potro&scaron;nju energije.<br />U istraživanju je utvrđeno da mliva sa približno istom vredno&scaron;ću geometrijskog srednjeg prečnika, dobijena na mlinu čekićaru i mlinu sa valjcima, imaju značajno različitu raspodelu veličine čestica. Na mlinu čekićaru dobija se &scaron;ira raspodela, sa većim sadržajem najkrupnijih i najsitnijih čestica, u poređenju sa mlinom<br />sa valjcima. Za proizvodnju mliva približno istog geometrijskog srednjeg prečnika, a pogotovo mliva sa relativno sličnom raspodelom veličine čestica,<br />potro&scaron;nja energije kod mlina sa valjcima značajno je manja u poređenju sa mlinom<br />čekićarom. &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; Potvrđeno je da peletiranje uzrokuje veliki intenzitet usitnjavanja čestica bez obzira na primenjene parametre. Međutim, određene kombinacije parametara mogu doprineti značajnijem očuvanju krupnih čestica. Parametar peletiranja koji najvi&scaron;e doprinosi<br />povećanju udela krupnih čestica u peletama je granulacija mliva koje se upućuje na<br />peletiranje. &Scaron;to je krupnija granulacija, udeo krupnih čestica u peletama će biti veći.<br />Rezultati optimizacije procesa peletiranja u prvoj fazi ukazuju da je u pogledu proizvodnje peletirane hrane za živinu, kada je poželjno očuvanje određene količine krupnih čestica, potrebno primeniti krupno mlevenje na mlinu čekićaru, uz<br />pode&scaron;avanje zazora između valjaka i matrice od 2 mm i uz sadržaj vode materijala od 17,5%. U drugoj fazi optimizacijom je utvrđeno da je potrebno koristiti debljinu matrice od 30 mm, najkrupniju granulaciju mliva na mlinu sa valjcima i vlagu od 17,5%. Pri proizvodnji peletirane hrane za živnu povoljnije je koristiti mlin čekićar, s obzirom da je utvrđeno da su čestice mliva dobijenog na čekićaru otpornije na usitnjavanje tokom peletiranja od čestica dobijenih na mlinu sa valjcima &scaron;to omogućuje očuvanje većeg broja krupnih čestica tokom peletiranja. Povećanje &scaron;irine zazora valjci-matrica nije poželjno prilikom peletiranja hrane za svinje jer se povećava intenzitet usitnjavanja čestica, a time i udeo najsitnije frakcije čestica. Sličano je i sa povećanjem debljine matrice. U prvoj fazi istraživanja, rezultati optimizacije pokazuju da je u cilju povećanja udela frakcija čestica srednje veličine (630 &ndash; 1600 &mu;m), kao i smanjenja sadržaja najsitnijih čestica (&lt; 125 &mu;m), potrebno primeniti najsitnije mlevenje na mlinu čekićaru, najveći sadržaj vode materijala (17,5%), dok zazor između valjaka i matrice treba podestiti da bude ne&scaron;to veći od 0,30 mm. I u drugoj fazi istraživanja optimizacija je ukazala da je najveći udeo čestica srednje veličine (630 &ndash;<br />1600 &mu;m), kao i najmanji udeo čestica &lt; 125 &mu;m, ostvaren pri peletiranju najsitnijeg<br />mliva dobijenog na mlinu sa valjcima. Pri tome sadržaj vode je potrebno podesiti na<br />17,5%, dok debljina matrice treba biti oko 28 mm.<br />Pri predloženim optimalnim parametrima peletiranja ostvaren je zadovoljavajući<br />kvalitet peleta, a potro&scaron;nja energije pelet prese bila je na prihvatljivom nivou.</p> / <p>In modern poultry and swine breeding, animal feed is rarely used in powder form but mainly pelleted after mixing of different ingredients. During pelleting process, granulation of the feed is compromised, i.e. coarse particles are<br />almost completely destroyed and the content of fine particles is strongly<br />increased. This doctoral thesis investigated the impact of changes in selected grinding and pelleting parameters on granulation of particles after pelleting. The goal was to achieve the quantity of coarse particles in pellets to be as high as possible, which is important in poultry nutrition. Another goal was to determine the combination of parameters that will increase, as much as possible, the content of particles medium in size and reduce the share of the smallest particles, which is important in swine nutrition. At the same time quality of the pellets must not be significantly degraded and energy consumption of pellet press should be as low as possible.<br />Independent pelleting parameters were corn granulation after grinding, the distance (gap) between the rollers and the die of pellet presses (roller-die gap), the thickness<br />of the pellet press die (die thickness) and the water content of pelleted material. The study was divided in two stages. In the first stage the corn was ground using a hammer mill and in the second stage, roller mill was used. Three different granulations were produced on both mills. Coarseness of the ground material increased from the finest material produced using the hammer mill to the coarsest material obtained at the roller mill. In the first stage, three different granulations produced at the hammer mill were pelleted in combination with three different roller-die gaps (0.30, 1.15 and 2.00 mm) and three different water contents of material (14.5%, 16.0% and 17.5%). In the second stage three different granulations produced at the roller mill were pelleted in combination with three different die thicknesses (24, 30 and 36 mm) and three different water content of material (14.5%, 16.0% and 17.5%). Thus, three parameters were varied at three levels in both stages and experiments were designed according to Box-Behnken design. Depended variables (responses) were: temperature of the pellet press die, specific energy consumption of pellet press, dust content in pellets, degree of starch gelatinization,&nbsp; particle size of the material after pelleting. For each of the responses, a second order polynomial model was defined and used for optimization of the pelleting process. It was determined that particle size distribution of material with similar geometric mean diameter, obtained with hammer mill and roller mill, is significantly different from each other. Hammer mill produced higher quantity of the coarsest and the finest particles comparing to roller mill. Energy consumption of roller mill for grinding to similar particle size distribution or similar geometric mean diameter is lower compared to hammer mill. Even though it was determined that secondary grinding of particles during pelleting is inevitable, certain combinations of pelleting parameters may contribute to significant preservation of large particles and to reduction of quantity of small particles. Results of optimization in the first stage indicated that for the production of pelleted poultry feed, when certain amount of coarse particles should be preserved, it is necessary to apply coarse grinding on hammer mill, with the roller-die gap of 2 mm and with material water content of 17.5%. In the second stage it was determined that it is necessary to use die with thickness of 30 mm, coarsest granulation at the roller mill and material water content of 17.5%. In the production of pelleted poultry feed it is better to use a hammer mill since it was found that the particles obtained on hammer mill are more resistant to secondary grinding than the particles obtained with the roller mill. Roller-die gap increase is not desirable during pelleting of swine feed because it increases secondary grinding, and thus the proportion of the smallest particles. Similar effect has an increase of the die thickness. In the first stage of the study, the results of the optimization showed that the largest quantity of medium-sized particles (630 &ndash; 1600 &mu;m), and the lowest quantity of the smallest particles (&lt; 125 &mu;m), were achieved with the finest grinding on the hammer mill. At the same time water content of 17.5% should be applied, while the roller-die gap should be close to 0.30 mm. In the second stage of the study, the largest quantity of medium-sized particles, and the lowest quantity of the smallest<br />particles, was achieved with the finest grinding on the roller mill. According to the optimization results, the water content should be set to 17.5%, while die thickness should approx. 28 mm. With the proposed optimal parameters, satisfactory pellet quality was achieved, and energy consumption of the pellet<br />presses was at an acceptable level.</p>

<p>Kvalitetno me&scaron;anje pra&scaron;kastih materijala, čestica ili granula je od izuzetnog inženjerskog, energetskog, ekonomskog i ekolo&scaron;kog značaja u raznim granama industrije: prehrambenoj, procesnoj, hemijskoj, farmaceutskoj industriji. Efikasnost me&scaron;anja, dizajn opreme i parametri procesa me&scaron;anja imaju značajan uticaj na kvalitet i cenu poluproizvoda ili finalnog proizvoda.<br />U ovoj tezi, prikazana je upotreba metode diskretnih elemenata (DEM) na modelovanje me&scaron;anja granula i/ili pra&scaron;kastih materijala (granulisani zeolit ili kukuruzna prekrupa) u različitim konfiguracijama statičkih me&scaron;ača Komax i Ross, kao i za modifikovane pužne transportere / predme&scaron;alice. Primenjen je i metod računske dinamike fluida (CFD) za modelovanje protoka fluida u Ojlerovom vi&scaron;efaznom modelu, za predviđanje pona&scaron;anja čestica unutar različitih konfiguracija statičkih me&scaron;alica.<br />Ispitivano je petnaest horizontalnih pužnih transportera sa nepromenljivog koraka, sa modifikovanom geometrijom, različitih dužina pužnice, sa dodatnim elementima na pužnoj spirali, radi istraživanja mogućnosti me&scaron;anja granulisanog materijala, tokom transporta materijala (granulisani zeolit).<br />Rezultati matematičkog modeliranja i numeričke simulacije su upoređeni sa odgovarajućim eksperimentalnim rezultatima na osnovu stepena pome&scaron;anosti me&scaron;avine, primenom kriterijuma relativne standardne devijacije (RSD). Zahvaljujući ovde postavljenim modelima moguće je uraditi optimizaciju geometrije i parametara sistema me&scaron;anja uzimajući u obzir kvalitet procesa me&scaron;anja i cenu finalnog proizvoda.</p> / <p>The quality mixing of powders, particles and/or granules obtain an engineering, energetic, economic and ecological importance of various technologies, food industry, pharmaceutical and chemical industry. The mixing efficiency, the design of equipment and mixing parameters exert a strong impact on quality and the price of intermediate or final product. In this thesis, the use of Discrete Element Method (DEM) is shown for modeling of granular and/or powder flow in various multiple Komax and Ross mixing applications, as well as for the modified screw conveyors premixers . Computational Fluid Dynamic (CFD) method was used for modeling of fluid flow through Eulerian multiphase model, for the prediction of particle displacement within the various static mixers configurations. Fifteen horizontal screw conveyors with invariant pitch, with modified geometry and different screw length , with some additional elements welded on the helix were tested for the possibility of granular material mixing during the material transport (granulated zeolite).<br />The results of the numerical simulation are compared with appropriate experimental results, according to relative standard deviation criterion (RSD). Application of this model provide the optimization of the geometry and parameters of mixing systems taking into account the quality of the mixing process and the cost of the final product.</p>