Effect of essential oils on survival of salmonella spp. in pork packaged in vacuum and modified atmosphere

I pored uloženih napora i dostignuća koja su ostvarena u prehrambenoj industriji na polju higijene klanja i proizvodne prakse, bakterije uzročnici bolesti prenosivih hranom u koje spada i Salmonella spp. kao jedan od najčešćih patogenih bakterija izolovanih iz mesa, i dalje uzrokuju milione slučajeva oboljenja godišnje na globalnom nivou, predstavljajući ne samo zdravstveni već i ekonomski problem, kako u razvijenim zemljama tako i zemljama u razvoju. Salmonella Enteritidis i Salmonella Typhimurium su serotipovi koji najčešće izazivaju salmonelozu ljudi, međutim sve se češće prijavljuju sliučajevi salmoneloze uzrokovane manje poznatim serotipovima, što naglašava potrebu za njihovom kontrolom. Iako se jaja i meso živine i dalje smatraju glavnim izvorom Salmonella spp., salmoneloza uzrokovana konzumiranjem kontaminiranog svinjskog mesa i proizvoda od svinjskog mesa je u porastu. Industrija mesa se suoči sa novim trendom organske proizvodnje, gde nema mesta za primenu do sada korišćenih hemijskih konzervanasa, od kojih neki ispoljavaju kancerogene i toksične osobine ili dovode do pojava alergija. Etarska ulja su biljni ekstrakti koji se izučavaju pre svega zbog antibakterijskih i antioksidativnih osobina ali i mogućnosti da se koriste kao zamena za sintetičke aditive u prehrambenoj industriji. Primena etarskih ulja može da smanji incidenciju bolesti prenosivih hranom, da produži održivost namirnica i odloži lipidnu oksidaciju. Etarsko ulje timijana i origana jedni su od deset najčešće korišćenih etarskih ulja za primenu u hrani. Cilj istraživanja u okviru ove doktorske disertacije bio je ispitivanje različitih načina pakovanja (vakuum i modifikovana atmosfera) i antimikrobnog efekta različitih koncentracija etarskih ulja origana i timijana (0,3%, 0,6% i 0,9%), na Salmonella spp. i mikrobiološki status mesa, kao i ispitivanje antioksidativnih osobina pomenutih etarskih ulja i njihovog efekta na oksidativne promene lipidne frakcije, fizičko hemijske osobine i prihvatljivost mlevenog svinjskog mesa. Kao sirovina za ispitivanje korišćeno je mleveno meso mišića buta svinja meleza Jorkšira x Landrasa. Na početku eksperimenta ispitan je hemijski sastav etarskih ulja (GC-MS), antioksidanti potencijal etarskih ulja (DPPH test, kapacitet neutralizacije •OH i NO• radikala FRAP test, lipidna peroksidacija) i minimalna inhibitorna koncentracija etarskih ulja timijana i origana, ali i aktivnih principa, eugenola, timola, karvakrola i cinamaldehida (mikrodiluciona metoda) potrebna za inhibiciju šest serovarijeteta Salmonella spp. (S. Enteritidis, S. Typhimurium, S. Infantis, S. Montevideo, S. Senftenberg, S. Givae) i koktel serovarijeteta odabranog za kontaminaciju mesa (S. Enteritidis, S. Typhimurium, S. Infantis, S. Montevideo)...Despite efforts and improvements in slaughter hygiene and food production techniques in the food industry, foodborne pathogens including Salmonella spp as one of the most often pathogen found in meat, still cause millions of episodes of illness annually worldwide, presenting not only health but also an economic problem in both developed and developing countries. Salmonella Enteritidis and Salmonella Typhimurium are serotypes mainly reported as causes of human salmonellosis, but outbreaks of salmonellosis caused by a rarer subspecies of Salmonella are increasing, which is why their control is needed. Eggs and poultry meat are still recognized as main sources of Salmonella infection in humans but salmonellosis caused by consuming contaminated pork meat and derived products are increasing. Moreover, the meat industry is challenged by the new trend of producing all-natural food, where is no place for artificial preservatives which may have some carcinogenic and toxic properties or may cause food allergies or sensitivities. Essential oils (EOs) are plants derived which gained attention mainly due to its antibacterial and antioxidative properties, and potential to be used as a replace for synthetic additives in the food industry. EOs can reduce the incidence of food-borne diseases, extend shelf-life and retard lipid oxidation. Thyme and oregano EO are one of the top ten EOs used as a preservative for food purposes. The aim of this PhD thesis was to evaluate the effect of different packaging conditions (vacuum and modified atmosphere) and different concentrations (0.3%, 0.6% and 0.9%) of thyme and oregano essential oils on survival of Salmonella spp., microbiological status of pork meat, as well as antioxidative properties if essential oils and their effect on lipid oxidation in meat, physicochemical parameters and organoleptic acceptability of meat. Meat used in present study was obtained from pork muscles from legs of different animals, crossbreeds Yorkshire x Landrace and minced in a grinder with 4 mm perforations in the grinding plates. At the beginning of the experiment chemical composition of EOs was determined (GC-MS analysis), as well as antioxidative capacity of EOs (DPPH test, nitric oxide and hydroxyl-radical scavenger capacity, FRAP assay, lipid peroxidation) and minimal inhibitory concentration (MIC) of EOs and active compounds e.g. thymol, carvacrol, eugenol and cinnamaldehyde (microdilution method) needed to inhibit the grow of six serotypes of Salmonella spp. (S. Enteritidis, S. Typhimurium, S. Infantis, S. Montevideo, S. Senftenberg, S. Givae) and the four-strain cocktail of Salmonella chosen to be used in meat contamination (S. Enteritidis, S. Typhimurium, S. Infantis, S. Montevideo)..

Optimization of bucket wheel excavator cutting parameters at mining of materials with increased strength

Otkopavanje materijala rotornim bagerom je veoma sloţen fiziĉko-mehaniĉki proces. Pokazatelji efektivnosti tog procesa zavise od velikog broja raznovrsnih ĉinilaca od kojih se posebno mogu istaći: fiziĉko-mehaniĉke karakteristike materijala koji se otkopava, reţim rada bagera i izbor tehnoloških parametara bloka, odreska i reza, geometrije vedrica i zuba itd. Poseban problem se javlja kod otkopavanja materijala povećane ĉvrstoće, što je ĉest sluĉaj na našim površinskim kopovima. Dimenzionisanje specifiĉne sile kopanja bagera prema manjim masama izuzetno ĉvrstog materijala je neracionalno i rešenje treba traţiti ili u otkopavanju ovih masa drugom opremom ili optimizaciji rada rotornog bagera tj. izboru optimalne vrste reza i parametara odreska u cilju smanjenja otpora na kopanje, smanjenja potrošnje energije i smanjenje dinamiĉkih uticaja na konstrukciju rotornog bagera. Dosadašnjim istraţivanjima ove problematike, ustanovljeno je da se izvesna poboljšanja u radu rotornog bagera na otkopavanju materijala sa povećanom ĉvrstoćom mogu postići optimizacijom odreĊenih konstruktivnih i tehnoloških parametara, ĉiji je osnovni cilj praktiĉno povećanje raspoloţive rezne sile bagera i maksimalno iskorišćenje raspoloţivih mogućnosti bagera uz maksimalnu zaštitu bagera od nepovoljnih dinamiĉkih udara tokom rada. Vrsta i parametri reza su osnovni tehnološki parametri ĉijom se optimizacijom moţe uticati na: smanjenje otpora kopanju u materijalima sa povećanom ĉvrstoćom, povećanje kapaciteta rotornog bagera, minimizaciju potrošnje energije i povoljnije dinamiĉko ponašanje konstrukcije bagera. To je ujedno i predmet istraţivanja ove disertacije, a osnovni cilj je da se kroz sprovedena istraţivanja definiše metodologija koja će se koristiti pri izboru i optimalnom korišćenju rotornih bagera na površinskim kopovima u uslovima radne sredine sa povećanim otporom kopanju. Istraţivanja u okviru doktorske disertacije su realizovana na teorijskom i eksperimentalnom nivou. Na taj naĉin je sagledan, otvoren i determinisan problem, sagledana moguća i odabrana optimalna rešenja i izvršena praktiĉna provera dobijenih rezultata u konkretnim uslovima radne sredine. Terenska ispitivanja, analiza dobijenih rezultata i optimizacija parametara reza pri otkopavanju materijala sa povećanom ĉvrstoćom na površinskom kopu Gacko pokazala su da se najbolji efekti rada rotornog bagera postiţu sa vertikalnim rezom debljine 0,20 m, širine 0,30 m, odnosno sa brzinom obrtanja strele rotora od 24 m/min. Dokazano je da je neophodno promeniti postojeću tehnologiju otkopavanja rotornim bagerom, ali i daljim kompleksnim istraţivanjima postaviti metodologiju optimizacije konstrukcije reznih elemenata rotora.Mining of material by a bucket wheel excavator is a very complex physical physical-mechanical process. Indicators of the effectiveness of this process depends on a number of various factors, of which in particular may be emphasized: physical-mechanical characteristics of the material to be mined, mode of excavator operation and selection of block technological parameters, slice and cut, and the geometry of the buckets and teeth, etc. A particular problem occurs in the excavation of materials with increased strength, which is often the case in our opencast mines. Sizing of excavator specific digging forces towards smaller masses of extremely hard material is irrational and a solution should be sought either in the excavation of these masses by other equipment or by optimization of bucket wheel excavator operation i.e. in the selection of the optimal type of cut and parameters of slices in order to reduce resistance to digging, reducing energy consumption and reducing the dynamic effects on the structure of the bucket wheel excavator. Current research of this issue, it was found that certain improvements in the operation of the bucket wheel excavator on the mining of materials with increased strength can be achieved by optimizing of some structural and technological parameters, whose main goal is virtually increasing the available cutting forces of the excavator and maximum utilization of the available options with maximum protection of the excavator from the adverse impact of dynamic impacts during operation. Type and parameters of cut are the basic technological parameters that contribute to optimizing may affect: reduction of mining resistance in materials with the increasing strength, increasing the capacity of the bucket wheel excavator, minimizing energy consumption and more favorable dynamic behavior of excavator structure. It is also the subject of this thesis, and the primary goal through conducted researches is to define methodology to be used during selection and the optimal use of bucket wheel excavators in opencast mines in the working environment with the increased resistance to mining. Researches within this thesis were implemented at the theoretical and experimental levels. In this way was perceived an open and determined problem, was reviewed possible, selected optimal solutions, and carried out in practice checkups of results obtained in the concrete conditions of the working environment. Field tests, analysis of the obtained results and optimization of cutting parameters during the mining of materials with increased strength in the opencast mine Gacko has shown that the best effects of excavator operation are achieved with vertical cut and thickness of 0.20 m, width 0.30 m, i.e. with the slewing speed of bucket wheel boom of 24 m/min. It has been demonstrated that it is necessary to change the existing mining technology by the bucket wheel excavator, but also with further complex research to set up a methodology of optimizing the structure of the bucket wheel cutting elements

Uticaj uzrasta pri prvoj oplodnji na reproduktivne, proizvodne i funkcionalne osobine krava simentalske rase

The effect of cow age at first insemination on productive and reproductive traits, as well as on longevity and lifetime production ones was examined in the Simmental cows housed at the 'Zlatiborski Suvati' (Mt. Zlatibor Pastures) Farm. The general linear model was used to calculate linear regression coefficients for the effect of age at first insemination on productive, reproductive traits, longevity traits and lifetime production traits The calculated linear regression coefficients suggested that the age at first insemination had a statistically significant effect (P lt 0.05) on milk, milk fat and 4% fat milk production in whole lactations (bxy=1.508, bxy=0.056 and bxy=1.464), a very high significant effect (P lt 0.001) on the age at culling and cow utilisation index ((bxy=1.386 and bxy=-0.020), and no significant effect (P>0.05) on other longevity traits. The age of cows at first insemination did not significantly affect (P>0.05) fertility and lifetime milk and milk-fat production traits. The presented results suggest that cow age at first insemination should be included in the models used in estimating breeding values of dairy cows.Uticaj uzrasta krava pri prvoj oplodnji na proizvodne i reproduktivne osobine i osobine dugovečnosti i životne proizvodnje ispitivan je kod krava simentalske rase smeštenih na farmi 'Zlatiborski suvati'. Opštim linearnim modelom izračunati su koeficijenti linearne regresije uticaja uzrasta pri prvoj oplodnji na proizvodne i reproduktivne osobine, kao i osobine dugovečnosti i životne proizvodnje Na osnovu izračunatih koeficijenata linearne regresije uzrast pri prvoj oplodnji statistički je značajno uticao (P lt 0.05) na proizvodnju mleka, mlečne mast i 4% masnog mleka u celim laktacijama (bxy=1.508, bxy=0.056 i bxy=1.464), vrlo visoko značajno (P lt 0.001) na uzrast pri izlučenju i indeks iskorišćavanja krava (bxy=1.386 i bxy=-0.020), dok na ostale osobine dugovečnosti nije imao signifikantan uticaj (P>0.05). Uzrast krava pri prvoj oplodnji nije imao značajnog uticaja (P>0.05) na osobine plodnosti i životne proizvodnje mleka i mlečne masti. Na osnovu prikazanih rezultata uzrast krava pri prvoj oplodnji trebalo bi uvrstiti u modele za procenu odgajivačke vrednosti mlečnih krava

Uticaj sistematskih faktora na dužinu bremenitosti kod krava Simentalske rase

The effect of systematic environmental factors on gestation length in Simmental cows was evaluated by calculating the least squares mean (LSM) and its error (SELSM), by analysis of variance and by calculating the coefficient of determination (R2). The study involved Simmental cows reared at three locations, including the Zlatiborski Suvati farm (n=578), the Dobričevo farm (n=964) and individual private farms at the Voćar Farming Cooperative in Kotraža (n=1263). The analysis included gestation length in Simmental cows as affected by continuous systematic factors (age at first conception) and discontinuous factors such as farm, calving season, birth season, parity group, calf sex, type of birth and the interaction of these factors. The effect of age at first conception was statistically significant (P lt 0.05). The discontinuous factors had a very high significant (P lt 0.001) effect on gestation length. The coefficient of determination was as low as 0.086 (8.6%), undoubtedly suggesting the small effect of the non-genetic factors on gestation length, given the fact that the trait is biologically determined and that it shows low variability.Uticaj sistematskih faktora okoline na dužinu bremenitosti analiziran je izračunavanjem sredine najmanjih kvadrata (LSM) i njegove greške (SELSM), analizom varijanse po primenjenom modelu i izračunavanjem koeficijenta determinacije (R2). Istraživanjem su obuhvaćene krave simentalske rase raspoređene na tri lokaliteta i to farmi Zlatiborski suvati (n=578), farmi Dobričevo (n=964) i individualna gazdinstva na području Zemljoradničke zadruge 'Voćar' iz Kotraže (n=1263). Na dužinu bremenitosti ispitivan je uticaj kontinuelnih sistematskih faktora (uzrast pri prvoj oplodnji) i dikontinuelnih faktora kao što su farma, sezona telenja i rođenja, grupe partusa, pola teladi, tipa rođenja i interakcija pomenutih faktora. Uticaj uzrasta pri prvoj oplodnji bio je statistički značajan (P lt 0.05), dok uticaj svih diskontinuelnih uticaja na trajanje bremenitosti bio je vrlo visoko značajan (P lt 0.001). Koeficijent determinacije iznosio je svega 0.086 (8.6%), što nedvosmisleno ukazuje na mali uticaj paragenetskih faktora na ispoljenost dužine bremenitosti obzirom da je ona biološki data i da se odlikuje niskom varijabilnošću

The effect of rearing system and length of fattening period on selected parameters of broiler carcass quality

This study involved analysis of some carcass quality parameters in broilers reared under two different non-industrial systems (extensive indoor and free range) at two different lengths of fattening period (56 and 63 days). The quality parameters tested included dressed carcass yield, dressing percentage, proportion of primal cuts (breast, drumstick, thigh, wing, pelvis and back) in dressed carcass, and proportion of major tissues (muscular tissue, bone and skin) in high-value carcass cuts (breast, drumstick and thigh). The objective of the study was to evaluate the effect of broiler rearing system, length of fattening period and gender on the carcass quality traits tested. The male broilers had a higher carcass weight at the slaughtering line at both lengths of fattening period, and the obtained differences were statistically significant. The broilers raised under extensive indoor system had a somewhat higher proportion of breast and a lower proportion of thigh and drumstick. A significant effect of gender was observed on these traits. The proportion of muscular tissue, bone and skin in the high-value primal cuts, including breast, drumsticks and thighs, dependent also on broiler gender and partly on the rearing system and length of fattening period

Uvoz nerastova - kontrola semena i mogućnost reklamacije

Serbia is one of the countries with the continuous import of breeding sows and boars. Boars are usually imported at the age of 4 to 6 months, in the period when the quality of the breeding males cannot be determined due to sexual immaturity (prepubertal and pubertal age). In this paper, the method and results of semen quality control in 40 imported young boars are described, and also the method of documenting the cause for action claim. In the case of suspicious semen quality it is necesseary to perform at least 3 consecutive controls in one month intervals in order to establish a final estimation of quality and usability of semen. Of 40 imported boars, 4 boars (10%) were subject of complaint due to: azoospermia (1 boar), absence or reduction of total and progressive motility, present sperm agglutination (2 boars), and increased number of pathological forms of spermatozoa (78%, 1 boar). Increased proportion of sperm with unstable chromatin structure (SCSA test - 33.2% and 37.1%) was established in two boars. To initiate the complaint it is necessary to have a sales contract that provides possibility for the reclamation, recognized methods of semen quality control and trustful business relationship between all interested parties.Srbija se svrstava u red zemalja sa kontinuiranim uvozom priplodnih nazimica i nerastova. Nerastovi se uglavnom uvoze u dobi od 4 do 6 meseci, u periodu kada se kvalitet priplodnjaka ne može pouzdano utvrditi usled polne nezrelosti (prepubertetsko ili pubertetska dob nerastića). U ovom radu opisan je postupak i rezultati kontrole kvaliteta semena kod 40 mladih nerastova iz uvoza, kao i način dokumentovanja razloga za pokretanje postupka reklamacije. Kod sumnjivog kvaliteta semena potrebno je izvršiti najmanje 3 uzastopne kontrole u razmaku od po mesec dana, kako bi se donela konačna ocena o kvalitetu semena i upotrebljivosti nerasta za priplod. Od 40 uvezenih nerastova, 4 su reklamirana (10%) usled: azoospermije (1 nerast), odsustva ili smanjenje ukupne ili progresivne pokretljivosti, uz prisustvo aglutinacija spermatozoida (2 nerasta), i povećanog broja patoloških formi spermatozoida (78%; 1 nerast). Kod dva nerasta zabeležen je povećan udeo spermatozoida sa nestabilnom strukturom hromatina (SCSA test - 33,2% i 37,1%). Za pokretanje reklamacije neophodno je imati kupoprodajni ugovor koji predviđa mogućnost reklamacije, priznate metode kontrole semena kao i izgrađen poslovni odnos poverenja zainteresovanih strana

Protective effects of some cholinolytics in armine poisoning

Ispitan je zaštitni efekat 9 holinolitika i jednog inhibitora holinacetilaze na miševima trovanim arminom. Zaštitni efekat kod 1 LD50 armina dobiven je s hidroksizinom, disipalorn i ponalidom. Antrenil i atropin metilnitrat u kombinaciji sa piridin aldoksim methloridom (PAM-2 CI) spasili su 50% tretiranih životinja od 4 LD50 armina, aturban i PAM-2 CI od 8 LD50 otrova.Nine cholinolytics and one choline aoetylase inhiihitor (Morin) have been examined as potential protecting agents against armine poisoning. Only Hydroxyzine, Disipal and Ponalid were found to protect mice against one LD50 of armine. In combination with pyridine 2-aldoxime methchloride (PAM-2-Cl) the best effect was found with Aturban, which protected 50 per cent of mice against 4 mg/kg of armine (X LD50). The quaternary cholinolytics Antrenyl and atropine, combined with PAM-2-Cl, protected about 50 per cent of animals against 4 X LD50 of armine, similarly to a combination of central cholinolytics. Tropenzylium and Hydroxyzine. Other cholinolytics showed weaker protective properties

Cerium oxide based nanometric powders: synthesis and characterization

Nanometric powders of solid solutions of cerium oxide were obtained by a modified glycine nitrate procedure. Solid solutions of the host compound CeO2 with one or more dopants in the lattice were synthesized. Rare earth cations (Re=Yb, Gd and Sm) were added to ceria in total concentration of x= 0.2 that was kept constant. The criterion in doping was to keep the value of lattice parameter of ceria unchanged. The lattice parameters were calculated by using the model that takes into account the existence of oxygen vacancies in the structure