Srpski crni tartuf tuber aestivum: mikrobiota I uticaj različitih režima smrzavanja na isparljiiva aromatična jedinjenja tokom skladištenja

The use of truffles in food is based mainly on the addition of artificial flavors, aiming to achieve an intense aroma in the products. As truffle is a natural product with nutritional and functional properties, it is important to find an optimal method for truffle storage. As the microbiota contribute to truffle aroma, the bacterial and yeast compositions in the rhizosphere and fruiting body of the truffle and the impact of different freezing methods on the volatile profile of the truffle Tuber aestivum during 90 days of the storage were determined. Bacteria and yeasts isolates were identified using 16s rRNA and 18s rRNA. The effect of freezing truffles at -20°C and -80°C with and without previous dipping in liquid N2 on the volatile compounds was observed using GC/MS. The results demonstrated that the isolated bacteria belonged to the phylum Proteobacteria, Firmicutes and Actinobacteria, and the identified species mainly belonged to Firmicutes, genus Bacillus sp. Isolated yeasts were identified as Cryptococcus sp., Debaromyces hanseinii, Candida fermentati and Rhodotorula mucilaginosa. The GC/MS analysis revealed that frozen truffle samples were richer in the compounds 2-butanone, 2-methyl-butanal, methanethiol and 2-butanol after freezing or during storage. The content of DMS, acetaldehyde, 3-octanone, ethanol, and 2-methyl-1-propanol significantly decreased immediately after freezing. Overall, the gained results indicated that freezing of truffles as a preservation method had profound effects on the volatile compounds, while previous dipping in liquid N2 showed no significant impact on the volatile profile of truffle Tuber aestivum.Primena tartufa u hrani se uglavnom zasniva na dodavanju veštačkih aroma, sa ciljem postizanja intenzivne arome tartufa u proizvodima. S obzirom na to da su tartufi proizvodi sa nutritivnim i funkcionalnim karakteristikama, važno je pronaći optimalan način za skladištenje tartufa. Pošto mikrobiota doprinosi aromi tartufa, sastav bakterija i kvasaca u rizosferi i plodonosnom telu srpskog tartufa, kao i uticaj različitih metoda smrzavanja na isparljiva jedinjenja tartufa Tuber aestivum ispitivan je tokom 90 dana skladištenja. Bakterije i kvasci su izolovani iz svežeg tartufa i izolati su identifikovani korišćenjem 16s rRNK i 18s rRNK. Uticaj smrzavanja tartufa na -20°C i -80°C sa i bez prethodnog potapanja u tečni N2 na sadržaj isparljivih jedinjenja ispitivan je korišćenjem GC/MS. Rezultati ispitivanja su pokazali da izolovane bakterije pripadaju carstvu Proteobacteria, Firmicutes i Actinobacteria, pri čemu identifikovane vrste uglavnom pripadaju Firmicutes, rod Bacillus sp. Izolovani kvasci su identifikovani kao Cryptococcus sp., Debaromyces hanseinii, Candida fermentati i Rhodotorula mucilaginosa. Analiza GC/MS je ukazala na razlike u profilu isparljivih jedinjenja svežeg i smrznutog tartufa. Smrznuti uzorci su više sadržali komponente kao što su 2-butanon, 2-metil-butanal, metanetiol i 2-butanol nakon smrzavanja ili tokom skladištenja. Sadržaj DMS, acetaldehida, 3-octanona, etanola, 2-metil-1-propanola značajno se smanjio odmah nakon smrzavanja. Dobijeni rezultati ukazuju da smrzavanje tartufa kao metoda konzervacije ima značajan uticaj na isparljiva jedinjenja, pri čemu potapanje u tečni N2 nije pokazalo značajan uticaj na isparljiva jedinjenja tartufa Tuber aestivum

The comparative analysis of thermal behaviour of a different thicknesses walls made from autoclaved aerated concrete blocks exposed to fire

In this paper a comparative analysis of thermal behavior of six partition walls with different thicknesses were presented. The walls were dimensions 3000 mm x 3000 mm made from autoclaved aerated concrete blocks with dimensions 625 mm x 200 mm and thicknesses 50 mm, 75 mm, 100 mm, 120 mm, 150 mm and 250 mm. All walls were exposed to standard fire test according the standard SRPS EN 834-1, non- combustibility test according the standard SRPS EN 1182 and surface spread of flame test according to SRPS U.J1.060. All walls were tested to fire resistance in vertical furnace with a data acquisition system, according to standard fire test. Standard furnace for testing construction consist of four two step burners in liquid fuel type of 296 kW manufactured by ECO FLAM. Two transmitters of differential pressure type 6321 manufactured by TESTO (Germany), with range 100 Pa installed inside the furnace were used for pressure measurement. Inside the furnace the temperature on six places with thermocouple type K were measures. The measure ranges of thermocouple type K were -2700C to 13720C. The temperatures on unexposed fire side were measured in nine places with thermocouple type T with measure ranges - 2700C to 4000C of according the national standard SRPS U.J1.090. The obtained temperature results depending of the time of reaching the critical temperature were presented for each wall thicknesses. The five identical cylindrical samples with high 50 mm and diameter 45 mm for non-combustibility test has been used. All samples have been tested in standard furnace for non-combustibility test. The average temperature in furnace and specimens were presented. Surface spread of flame testing is carried out according to standard SRPS U.J1.060, if the coating material is based on organic or mixed materials. The samples for these test are with dimensions 900 x 230 mm

The Sensory Quality and Volatile Profile of Dark Chocolate Enriched with Encapsulated Probiotic Lactobacillus plantarum Bacteria

peer-reviewedCocoa and dark chocolate have a wide variety of powerful antioxidants and other nutrients that can positively affect human health. Probiotic dark chocolate has the potential to be a new product in the growing number of functional foods. In this study, encapsulated potential probiotic Lactobacillus plantarum 564 and commercial probiotic Lactobacillus plantarum 299v were added in the production of dark chocolate. The results show very good survival of probiotic bacteria after production and during storage, reaching 108 cfu/g in the first 60 days and over 106 cfu/g up to 180 days. No statistically significant difference (p > 0.05) in chemical composition and no major differences in the volatile profiles between control and experimental chocolate samples were observed, indicating no impact of probiotic bacteria on compositional and sensory characteristics of dark chocolate. The sensory evaluation of control and both probiotic dark chocolate samples showed excellent sensory quality after 60 and 180 days of storage, demonstrating that probiotics did not affect aroma, texture and appearance of chocolate. Due to a high viability of bacterial cells and acceptable sensory properties, it can be concluded that encapsulated probiotics Lb. plantarum 564 and Lb. plantarum 299v could be successfully used in the production of probiotic dark chocolate

Fire resistance tests for fire dampers

Passive fire protection is civil engineering discipline which is very popular for research and development of new construction products and test standards. The primary function of passive fire protection product is to achieve the declared fire resistance. Fire resistance of a construction product is expressed as a time interval (30 min, 60 min, 90 min, 120 min ...) in which certain properties of the tested product are preserved. In the given time intervals, it is necessary for the tested product to maintain the thermal insulation properties (I), integrity (E) and additional properties prescribed by the test standard related to the tested product. The fire damper represents part of HVAC system installed on walls which are fire resistance barriers [2]. Additional properties related to fire-resistant service installations- fire dampers (hereinafter only fire dampers) are the leakage on the fire damper in the cold state and the leakage of fire damper (S) during the fire test. In order to determine the previous properties, a test installation for fire dampers was formed, which consists of: installed damper in the test wall, duct and pipeline system, system for measuring the volume flow, cooler and a fan. All the obtained results are graphically presented in the paper and serve for the purpose of determining the mentioned fire properties of dampers and for the purpose of fire resistance classification of construction products

Određivanje koeficijenta prolaza toplote i otpornosti prema požaru zida izrađenog od giter-blokova

Unazad par godina, sve više pažnje se posvećuje poboljša-nju energetske efikasnosti zgrada. Iz tog razloga se posebna pažnja obraća na dokazivanje što boljih performansi proiz-voda koji se ugrađuju u objekte. U radu je urađena numerička i eksperimentalna analiza za dobijanje koeficijenta prolaženja toplote. Analiziran je giter-blok ispunjen kamenom vunom. Eksperimentalna analiza za dobijanje koeficijenta prolaženja toplote je urađena u skladu sa standardom SRPS U. J5.060, dok je numerička analiza izvršena primenom softvera THERM, čiji se proračun bazira na standardu ISO 15099. U radu je prikazana uporedna analiza rezultata dobijenih eksperimentalnim i numeričkim putem. Eksperimentalnim putem je dobijena vrednost za otpornost prema požaru za zid izrađen od šupljih giter-blokova. Zid je ispitan u skladu sa standardom SRPS EN 1364-1

Tehnički zahtevi za prijem radova na koloseku

U radu se predstavlјaju tehnički zahtevi za prijem radova na koloseku normalne širine (1435 mm) u zastoru od tucanika u skladu sa evropskim standardom EN 13231-1, koji je 2014. godine usvojen kao srpski standard. Prijem radova se odnosi na građenje novog, kao i na rekonstrukciju, obnovu i odr-žavanje postojećeg koloseka. U radu se ukazuje na to da, uprkos uspostavljenom zakonskom okviru u Republici Srbiji, domaća tehnička regulativa još uvek nije harmonizovana sa zahtevima pomenutog standarda. Pored toga, ukazuje se na važnost definisanja procedura za sprovođenje merenja vrednosti referentnih parametara i kontrole stanja koloseka, kao i postupaka za dokumentovanje rezultata merenja i sprovedenih kontrola. Prikazane su propisane tolerancije za parametre geometrije koloseka i elemente konstrukcije gornjeg stroja koloseka prema zahtevima EN 13231-1. Posebno se ukazuje na važnost utvrđivanja roka za izvršanje prijema radova u ugovoru sklopljenom između upravljača infrastrukture i izvođača radova

UIC preporuke za projektovanje železničkih mostova

This paper discusses the basic principles of interaction track/bridge. Influences of different bridge structures on the bridge expansion length were analyzed in order to avoid expansion joints in CWR track. Influences of track and bridge superstructure, as well as bridge support stiffness on the mentioned interaction were considered. In addition, performance requirements for rail fastening systems and longitudinal track restraint on bridge were considered. UIC (International Union of Railways) recommendations for design of railway bridges were presented. The aim of this paper is providing the basis for improvement of the existing technical regulations in the field of railway infrastructure, as well as its harmonisation with EU regulations.Ovaj rad razmatra osnovne principe interakcije kolosek/most. Analizirani su uticaji različitih konstrukcija mostova na dilatacionu dužinu mosta kako bi se izbegla dilataciona sprava u koloseku sa kontinualno zavarenim šinama. Razmatrani su uticaji gornjeg stroja mosta kao i krutosti oslonaca mosta na pomenutu interakciju. Takođe, razmatrani su tehnički zahtevi za sisteme šinskih pričvršćenja i podužni otpor koloseka na mostu. Predstavljene su UIC (Međunarodna železnička unija) preporuke za projektovanje železničkih mostova. Cilj rada je stvaranje osnove za unapređenje postojeće tehničke regulative u oblasti železničke infrastrukture i njena harmonizacija sa EU regulativom

Klimatski uticaji na napone u kontinualno zavarenim šinama u kolosecima na mostovima u Srbiji

Vehicle/track/bridge interaction causes additional stresses in CWR on the bridge, which include stress in rails due to temperature changes in the bridge deck, vertical bending of bridge deck, and braking/acceleration of railway vehicles on the bridge deck. Critical analysis of additional tensile stresses in CWR on the bridge using Smith diagram was performed and presented in this paper. Furthermore, results of rail temperature measuring at several monitoring locations in Serbia were presented. The influence of the local climate conditions and neutral rail temperature on the temperature stress in CWR was analysed. The paper points out that the prescribed values of additional stresses in CWR have to include influence of real local climate conditions on track stability on the bridge.Interakcija vozilo/kolosek/most dovodi do dodatnog naprezanja u kontinualno zavarenim šinama na mostu, što uključuje napone u šinama usled temperaturne promene u konstrukciji gornjeg stroja mosta, napone u šinama usled savijanja konstrukcije gornjeg stroja mosta u vertikalnoj ravni pod saobraćajnim opterećenjem, kao i napone u šinama usled pokretanja/kočenja železničkih vozila na mostu. U radu je predstavljena kritička analiza dodatnih napona zatezanja u kontinualno zavarenim šinama na mostu pomoću Smitovog dijagrama. Osim toga, predstavljeni su rezultati merenja temperature na nekoliko mernih mesta na železničkoj mreži u Srbiji. Analiziran je uticaj lokalnih klimatskih uslova i neutralne temperature u šini na napone od temperaturne promene u kontinualno zavarenim šinama. U radu se ističe da propisane vrednosti dodatnih napona u kontinualno zavarenim šinama moraju uključiti uticaj stvarnih lokalnih klimatskih uslova sa aspekta stabilnosti koloseka na mostu

Methods for track stiffness measurement - State of the art

Track stiffness is a parameter which significantly influences to the track geometry deterioration, rail fatigue and deterioration of other superstructure and substructure components during the track service life. Track stiffness measurement has great theoretical and practical importance for the design of new railway lines, as well as for upgrade and maintenance of existing railway lines. This paper analyses standstill and continuous measurement methods for static and dynamic track stiffness, which are used worldwide. In addition, it presents measurement principles and performances used for inspection vehicles and devices, and guidelines for selection of the optimal method for stiffness measurement depending on the user requirements