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Solutions of milk protein concentrate, whey protein concentrate and bovine serum albumin (BSA) were treated with polyacrylic hydrogel to establish whether the hydrogel could be used for decontamination of heavy metal ions from milk protein-based products. The obtained results indicated that swelling of hydrogel in these solutions had different effects on their mineral, trace element and total protein content. Total protein and phosphorus content increased in milk protein concentrate and whey protein concentrate solutions after swelling of hydrogel without changes in their protein compositions. On the other hand, the protein content in BSA solution decreased after swelling. The content of Na did not change in milk protein concentrate solution, whereas it significantly increased in whey protein concentrate solution after hydrogel swelling. The content of Ca and Mg was reduced after the swelling in milk protein concentrate and whey protein concentrate solutions for 20.3-63.4 %, depending on the analysed sample and the mineral. The content of Zn did not change during swelling, whereas the content of Fe, Cu, Mn, Ni and Pb significantly decreased after hydrogel swelling in all analysed samples. According to the obtained results, the addition of polyacrylic hydrogel to milk and whey protein concentrate solutions can significantly decrease the content of heavy metal ions without affecting their protein composition. Therefore, this work could be useful in developing a new technological process for heavy metal purification of milk protein-based products.

Activity of ALS enzyme extracted from leaves of Xanthium strumarium L. (XS1, XS2) and Helianthus annuus L. (HA1, HA2, HA3) populations were studied in vitro in the presence of different nicosulfuron concentrations (0; 0,01; 0,1; 1; 10, 100 μM). This activity was recorded based on acumulation of acetoin per mg of protein during time interval of 1 min (nmol acetoin/min/mg protein). Nicosulfuron was reduced ALS enzyme activity in all studied populations, wherein the level of reduction depended on population and herbicide concentracion. It was confirmed that differences in susceptibility of X. strumarium populations to nicosulfuron were not consequence of altered ALS enzyme activity, while differences in susceptibility of H. annuus populations can be in relation with its altered activity. Aktivnost ALS enzima ekstrahovanog iz listova populacija Xanthium strumarium L. (XS1, XS2) i Helianthus annuus L. (HA1, HA2, HA3) je ispitivana in vitro u prisustvu različitih koncentracija (0; 0,01; 0,1; 1; 10, 100 μM) nikosulfurona. Ova aktivnost je određena na osnovu akumulacije acetoina po mg proteina u toku vremenskog perioda od 1 min (nmol acetoin/min/mg protein). Nikosulfuron je redukovao aktivnost ALS enzima u svim ispitivanim populacijama, pri čemu je nivo redukcije zavisio od populacije i koncentracije herbicida. Potvrđeno je da razlike u osetljivosti populacija X. strumarium na nikosulfuron nisu posledica izmenjene aktivnosti ALS enzima, dok se razlike u osetljivosti populacija H. annuus mogu dovesti u vezu sa njegovom izmenjenom aktivnošću.

Poslednjih godina istraživanju soje poklanja se velika pažnja zbog povoljnih zdravstvenih efekata. Mnoge studije su utvrdile u zrnu soje prisustvo komponenti poput proteina, dijetalnih vlakana, masnih kiselina, izoflavona i drugih fitohemikalija, koje povoljno deluju na organizam. Sirova okara, poznata i kao "sojina pulpa", je nusprodukt u priozvodnji sojinog mleka. To je belo-žućkasta materija koja se sastoji od nerastvorljivih delova semena soje (uglavnom semenjače) koji ostaju na filteru pri filtriranju usitnjenog kuvanog zrna soje pri proizvodnji sojinog mleka (Jimenez-Escrig et al., 2008). Cilj ovog rada je bio da se proceni uticaj metoda polupogonskog postrojenja koje koristi hidrotermičku obradu sojinog zrna u proizvodnji sojinog mleka (HTC obrada; visoka temperatura i povišen pritisak/kratko vreme) na sadržaj i aktivnost hranljivih komponenti okare, pripremane od šest različitih genotipova soje, kao i da se proceni mogućnost korišćenja okare u pripremi hrane za ribe. Može se pretpostaviti da će primenjeni HTC postupak, koji je sličan procesu ekstrudiranja, koji se najčešće koriste u proizvodnji hrane za ribe (visoka temperatura/kratako vreme), dati okaru povoljnih svojstava, pogodna za ishranu riba. Pored toga, obzirom da je optimalna pH vrednost vode za uzgoj riba od 7.0 do 8.0 (Zhanga et al., 2011), različita od izoelektrične tačke (Ip) glavnih proteina okare može se pretpostaviti da se proteini okare neće taložiti u mulju, već će ostati da plutaju u vodi. Glavne komponente okare dobijene primenjenim HTC postupkom su ugljeni hidrati (51.25-59.25%) i proteini (31.81-40.36%). Mateos-Aparicio et al. (2010b) ističu veoma povoljnu antioksidativnu aktivnost okare, koju uglavnom pripisuju polisharidima semenjače sojinog zrna, pre svega pektinima, iako ističu da se ne može isključiti ni doprinos belančevina. Ovakva istraživanja ukazuju na mogućnost delovanja okare kao komponete u ishrani riba u smislu odbrane od antioksidativnog stresa. Visok sadržaj proteina, čini okaru potencijalno dobrim izvorom biljnih proteina, niske cene, za ishranu ljudi i životinja. Visok sadržaj i vrlo dobre funkcionalne karakteristike proteina okare (Mateos-Aparicio et al., 2010a), ukazuju na to da mogu biti pogodni kao dopuna hrane za ribu u smislu vezivnog medijuma za druge aktivne i hranljive komponente u proizvodu, pri čemu doprinose nutritivnoj vrednosti hraniva. Štaviše, odnos esencijalnih amino kiselina u ukupnom aminokiselinskom sastavu proteina okare je sličan kao u sojinom mleku i tofuu (Vang i Cavins, 1989). Glavni proteini okare su bazni, 7S globulin (Bg7S; 24.61-28.37%) i glicinin (11S globulin; 28.49-33.11%). Poznato je da je Bg7S glikoprotein bogat cisteinom (Omi et al., 1996) što povećava nutritivnu vrednost proizvoda. Proteini soje nisu nutritivno idealni proteini, obzirom da ispoljavaju neželjeni efekat na metabolizam nakon konzumiranja sirove sojine sačme, što se pripisuje prisustvu tripsin inhibitora (TI) i lektina. Tripsin inhibitorska aktivnost ispitivanih uzoraka je veoma mala (4.82-7.99%) što ukazuje da okara ne bi ispoljavala antinutritivni efekat na organizam, tim pre što se veruje da postizanje zadovoljavajućeg nivoa TIA dovoljno smanjuje aktivnost lektina, obzirom da su inhibitori termički stabilniji nego lektini (Friedman i Brendon, 2001).

In this research new experimental data for the pressure dependence of the viscosity of beta-lactoglobulin solution are presented. The experimental investigation is based on in-situ viscometric measurement technique which provides an observation of the high-pressure-induced changes of beta-lactoglobulin solution during the treatment. This method refers to a rolling ball viscometer that is adapted for the use at high pressures and has a variable inclination angle. The estimation of the viscosity has been done in order to detect reversible and irreversible conformational changes of beta-lactoglobulin. For investigation protein solutions concentration 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06 g/g were used. The sample solutions are exposed to pressure of 0.1-600 MPa. The results showed that there is no significant effect of 100 MPa pressure on the viscosity of beta-lactoglobulin solutions. With increasing pressure, between 100 and 300 MPa, the viscosity of beta-lactoglobulin solutions increase. Pressure above 300 MPa causes further increase of the viscosity due to nonreversible and more extensive effects on protein, e.g. unfolding of monomeric proteins and aggregation. The structural changes of the beta-lactoglobulin under high pressure affect the hydration of the beta-lactoglobulin molecules. At pressure between 100 and 300 MPa there is a significant increase in relative hydration due to structural changes and increase in number of water molecules which are associated with protein molecules. Higher pressure cause protein aggregation due to formation of intermolecular disulfide bonds and irreversible denaturation and aggregation occurs. Because of that, there is no changes in protein hydration, moreover, the hydration of beta-lactoglobulin molecules have a small decreases at pressure between 400 and 600 MPa.

White brined cheeses are made traditionally, without the addition of starter cultures and fermentation occurs as a result of lactic acid bacteria naturally present in milk. The aim of the study is to identify strains to be used as starter cultures in commercial cheese production. A total of 65 autochthonous lactic acid bacteria from 15 artisan cheeses were isolated and studied. All strains were tested for their Gram reaction, catalase test, acidification activity, growth ability with 20, 40, 60g NaCl/l, proteolytic ability to hydrolyze β-casein by SDS PAGE electrophoresis and biochemical identification with API 50CHL and API RAPID ID 32 Strep. Biochemical identification showed that mesophilic microflora was dominant and 47,7% of the isolates were classified as Lactococcus, 10,7% as Enterococcus, 35,4% as Lactobacillus and 3,1% as Leuconostoc. Dominant lactocci strain was Lactococcus lactis ssp. lactis (35,4%) but the presence of citrateutilizing bacteria Lactococcus lactis ssp. lactis bv. diacetylactis, as aroma enhancer is significant. For lactobacilli dominant strain was Lactobacillus para. paracasei (21,5%). Isolated strains varied significantly in acid production, from very fast and good acid producers (some strains of Lactococcus lactis ssp. lactis reduced the pH lt 4.8), to very poor ones. All isolated lactic acid bacteria grew in 20 and 40g NaCl/L, while 25 isolates grew in 60g NaCl/L. Isolates showed different proteolytic ability to hydrolyze β-casein. Some of them very extensively degraded β-casein, the others demonstrated inferior activity. Screening important attributes of autochthonous lactic acid bacteria demonstrated that several bacterial strains are potentially useful as new starter cultures for industrial production of cheeses. . Beli sirevi u salamuri se prave tradicionalnim postupkom, bez dodavanja starter kultura, pa se proces fermentacije odigrava pod uticajem bakterija mlečne kiseline koje su prirodno prisutne u mleku. Cilj ovog rada je pronalaženje sojeva bakterija mlečne kiseline, koji bi mogli da se primene kao starter kulture u komercijalnoj proizvodnji sireva. Iz 25 uzoraka sireva izolovano i okarakterisano je 65 izolata autohtonih bakterija mlečne kiseline. Za sve sojeve je ispitano: bojenje po Gramu, katalaza test, acidogena aktivnost, sposobnost rasta na 20, 40, 60g NaCl/l, proteolitička sposobnost razgradnje β-kazeina SDS PAGE elektroforezom i biohemijska identifikacija primenom API 50CHL i API RAPID ID 32 Strep. Biohemijskom identifikacijom je utvrđeno da je mezofilna mikroflora dominantna, a 47,7% izolata je identifikovano kao Lactococcus, 10,7% kao Enterococcus, 35,4% kao Lactobacillus i 3,1% Leuconostoc. Dominantne laktokoke su bile Lactococcus lactis ssp. lactis (35,4%), a, takođe, značajno je bilo prisustvo citrat pozitivnih bakterija Lactococcus lactis ssp. lactis bv. diacetylactis, kao producenata arome. Od laktobacila dominantni su bili sojevi Lactobacillus para. paracasei (21,5%). Izolovani sojevi su se značajno razlikovali u acidifikacionoj sposobnosti, od veoma brzih i dobrih producenata kiseline (neki sojevi Lactococcus lactis ssp. lactis su snižavali pH lt 4.8) do veoma slabih acidogena. Svi izolati bakterija mlečne kiseline su dobro rasli u prisustvu 20 i 40g NaCl/l, dok je 25 izolata raslo u prisustvu 60g NaCl/L. Izolati su pokazali različitu proteolitičku sposobnost hidrolize β-kazeina. Neki su veoma intezivno hidrolizovali β-kazein, dok su drugi bili potpuno inferiorni u pogledu ove sposobnosti. Ispitivanjem karakteristika koje su važne za starter kulture pokazalo se da među autohtonim bakterijama mlečne kiseline ima i bakterija koje bi mogle da se primene kao nove starter kulture u industrijskoj proizvodnji sireva. .

Autochthonous lactic acid bacteria, isolated from traditional white brined cheeses, were applied as starter cultures in cheese production. The effects of their activity were studied during 90 days of white brined cheeses ripening. The cheese A was produced with Lactococcus lactis ssp. lactis 53, Lc. lctis ssp. lactis bv. diacetylactis 07, Lactobacillus paracasei 08 and cheese B was made with Lactococcus lactis spp. lactis 19, Lc. lactis ssp. cremoris 56, Lc. Lactis ssp. lactis bv. diacetylactis 07, as starter cultures. At each ripening time (30-60-90 days), changes of starter culture cells number and chemical composition of cheeses were monitored. Proteolysis was assessed by the water-soluble fractions (WSN), soluble fractions in 5%PTA (PTA-N) and SDS PAGE electrophoresis. The number of starter culture cells maintained at the high level of 6-8 log CFU/g, during the monitored cheese ripening period. There was no significant influence of the different starter cultures on the gross chemical composition, but the course of proteolytic changes was slightly different. The cheese A exhibited the higher rate of proteolysis in the early ripening stages. At 30-day-old cheese A the content of WSN/TN and PTA-N/TN was 16.54% and 2.54%, while residual αs-casein and β-casein were 26.12% and 36.71% respectively. Data for the content of WSN/TN and PTA-N/TN of cheese B was 14.36% and 2.41%, while residual αs-casein and β-casein were 52.37% and 46.11% respectively. At the end of observed ripening period (90 days), the proteolytic changes of cheese B were more intensive (residual αs-casein and β-casein were 17.33% and 18.43%, respectively) than of cheese A (22.58% and 33.63%, respectively). The sensory evaluation showed that white brined cheeses achieved high total scores at the each ripening time. Isolated and selected autochthonous LAB could be applied as starter culture in white brined cheese production. The using of autochthonous LAB provides white brined cheese with specific sensory characteristics, as well as high and standard product quality. . Autohtone bakterije mlečne kiseline, izolovane iz tradicionalnih belih sireva, primenjene su kao starter kulture u proizvodnji sireva u salamuri. Uticaj njihove aktivnosti na zrenje sireva je praćen tokom 90 dana zrenja. Sir A je proizveden primenom starter-kulture: Lactococcus lactis ssp. lactis 53, Lc. lctis ssp. lactis bv. diacetylactis 07, Lactobacillus paracasei 08, a sir B: Lactococcus lactis spp. lactis 19, Lc. lactis ssp. cremoris 56 i Lc. Lactis ssp. lactis bv. diacetylactis 07. Promene hemijskog sastava sireva su praćene tridesetog, šezdesetog i devedesetog dana zrenja. Proteolitičke promene su praćene određivanjem rastvorljivog azota u vodi (RN), rastvorljivog azota u 5% fosfovolframskoj kiselini (PTA-N) i SDS PAGE elektroforezom. Primena različitih starter-kultura nije značajno uticala na hemijski sastav sireva, osim kod proteolitičkih promena, koje su se značajno razlikovale tokom zrenja sireva. Kod sira A je utvrđena jača proteolitička razgradnja u početnoj fazi zrenja. U tridesetom danu zrenja sira A sadržaj RN u ukupnom azotu (RN/UN) iznosio je 16,54%, a PTA-N/UN 2,54%, dok je rezidualni αs-kazein bio 26.12%, a rezidualni β-kazein 36.71%. Sadržaj RN/UN i PTA-N/UN kod sira B iznosio je 14.36% i 2.41%, a sadržaj rezidua αs-kazeina i β-kazeina 52.37% i 46.11%. Na kraju posmatranog perioda zrenja (devedeseti dan), proteolitičke promene kod sira B bile su intenzivnije (rezidualni αs-kazein 17.33% i β-kazein 18.43%), nego kod sira A (22.58% i 33.63%). Senzorna ocena je pokazala da su sirevi A i B ocenjeni visokim ocenama tokom celog perioda zrenja. Izolovane i selektovane autohtone BMK mogu da se primene kao starter-kulture u proizvodnji belih sireva u salamuri. Upotreba autohtonih BMK obezbeđuje specifična senzorna svojstva ovih sireva, kao i visok standardan kvalitet. .

The severe heat treatment of milk designed for production of cheese (temperature higher than 85'C applied during the period of 10 minutes and more), results in formation of chemical complex between casein and whey proteins, signed as: milk protein coaggregates. Therefore, whey proteins are incorporated in curd, and cheese made of this milk shows some differences compared to traditionally made cheese, both by its composition and sensor characteristics, above all the texture of curd. Changes of proteins and products of their degradation are the most significant of all the changes that appear during the ripening of cheese. Therefore the ripening of cheese usuialy implies changes of proteins. Size and depth of proteolitical changes are connected to technological production process, ripening conditions and microbial activity. That is the reason why these changes are not the same in different cheese varieties, and why degradatiason of proteins has the main influence on sensor and Theological characteristics of cheese. The assumption of this research was that both heat treatment of milk and curd processing have influence on characteristics of proteins as substrate. During ripening, proteins are hydrolyzed, and presence of whey proteins influences lower casein content in total protein content of cheese. The influence of whey proteins on cheese characteristics is still the object of research. Factors as cheese variety, amount of whey proteins, state of whey proteins (native or denaturized), and degree of their aggregation with casein, influence the degree of cheese characteristics changes. During ripening of experimental cheeses for 4 months, nitrogen matter changes were observed. Significant changes of milk proteins, regarding increase of soluble nitrogen matter content, were observed. Soluble nitrogen content after production, 15, 30, 60 and 120 days of ripening was: 135.48 mg%, 358.72 mg% 473.52 mg%, 672.32 mg% and 845.13 mg%, respectively. Along with soluble nitrogen content increase, coefficient of ripening increased and for the same ripening period was: 4.42%, 10.14%, 12.95%, 18.21% and 23.60%, respectively. Primena oštrijih termičkih tretma-na mleka (na temperaturama višim od 85°C, u dužem vremenskom periodu, 10 minuta i duže), namenjenog za proizvodnju sira u poređenju sa termičkim tretmanima koji se primenjuju po tradicionalnom načinu proizvodnje, dovodi do formiranja hemijskog kompleksa između kazeina i serum proteina, koji su u literat uri označeni kao koagregati proteina mleka. Usled toga dolazi do inkorporiranja serum proteina u gruš, a dobijeni sir se razlikuje od tradicionalnih sireva kako po tehnološkom procesu proizvodnje, tako i po senzornim karakteristika-ma, a pre svega po teksturi sirnog testa kao i ukusu. U nizu promena koje se dešavaju u siru tokom zrenja, promene na proteinima i njihovim produktima razgradnje su najznačajnije, pa se u literaturi pod zrenjem sireva u užem smislu podrazumevaju promene nastale na proteinima. Obim i dubina proteolitičkih promena su u tesnoj vezi sa tehnologijom izrade sireva, uslovima zrenja i aktivnošću mikro-organizama, te su ove promene karakteristične za pojedine vrste sireva i imaju presudan uticaj na formiranje senzornih karakteristika konzistencije i drugih reotoških karakteristika sira. U okviru ovih istraživanja pošlo se od pretpostavke da će primenjeni režim termičke obrade mleka, kao i način obrade gruša, imati odgovarajući uticaj na karakteristike proteina kao supstrata, koji podleže hidrolizi tokom zrenja zbog prisustva serum proteina koji utiču na smanjenje sadržaja kazeina u ukupnim proteinima sira. Uticaj serum proteina na karakteristike sireva su još uvek predmet izučavanja. Faktori kao što su varijetet sira, količina serum proteina stanje serum proteina (nativno ili denuturisano) i stepen u kom su agregirani sa kazeinom, utiču na stepen promena karakteristika sira. Tokom zrenja oglednih sireva koje je trajalo 4 meseca praćene su promene na azotnim materijama. Uočene su značajne promene na proteinima mleka, koje se ogledaju u povećanju sadržaja rastvorljivih azotnih materija. Sadržaj rastvorljivog azota nakon proizvodnje, 15, 30, 60. i 120-og dana zrenja prosečno je iznosio: 135,48 mg/100 g, 358,72 mg/100 g, 473,52 mg/100 g, 672,32 mg/100 g i 845,13 mg/100 g. Porastom sadržaja rastvorljivog azota, povećavao se i koeficijent zrelosti, koji je u istom periodu zrenja iznosio u proseku 4,42%, 10,14%, 12,95%, 18,21% i 23,60%.

High nutritional value expressed with well balanced essential amino acid ratio, as well as favorable physic-chemical properties, make whey proteins very interesting ingredients for food industry and other industry branches. Whey proteins are mostly used for the improvement of nutritive value of the final product, as well as for the attaining certain technological-functional properties of product, such as foam or gel forming and emulsion forming and stabilization. Wide palette of products based on whey proteins is well know and whey protein concentrates, isolates and hydrolysates have the widest appliance. However, in recent world literature, more and more data show significant therapeutic effect of some less represented whey proteins, even in a medical treatment of the most serious illnesses. Refined whey proteins have defensive role in organism and therapeutic function, which opens possibility of refined whey protein industry development. Visoka nutritivna vrednost izražena dobro izbalansiranim odnosom esencijalnih aminokiselina, kao i povoljne fizičko-hemijske osobine čine serum proteine vrlo interesantnim ingredijentima u prehrambenoj i drugim granama industrije. Serum proteini se najčešće koriste u cilju poboljšanja hranljive vrednosti finalnog proizvoda, kao i radi postizanja određenih tehnološko-funkcionalnih svojstava proizvoda, poput obrazovanja pene ili gela, obrazovanja i stabilizacije emulzije. Danas je poznata široka paleta proizvoda na bazi serum proteina, pri čemu su proteinski koncentrati, izolati i hidrolizati našli najširu primenu. Međutim, u savremenoj svetskoj literaturi sve je više podataka o značajnom terapeutskom efektu pojedinih manje zastupljenih serum proteina čak i pri lečenju i najtežih oboljenja, što otvara mogućnost razvoja industrije prečišćenih proteina surutke, koji imaju odbrambenu ulogu u organizmu i terapeutsku funkciju.

In 2002, a johnsongrass population survived the application of ALS inhibiting herbicides in the locality of Zemun Polje, Serbia and Montenegro. This locality is known to have been treated with ALS inhibitors for years which may be considered the main cause of selection for herbicide resistance (R). The indices of resistance (IR=1.00 to IR=1.14) of the analyzed morphometric parameters show that no significant difference in susceptibility to nicosulfuron was found between the R and susceptible (S) populations. However, when a more sensitive method of monitoring ALS activity in vivo was employed, the index of resistance (IR=15.95) obtained by comparing enzyme inhibition in the two populations showed that nicosulfuron inhibited the enzyme in the S population of johnsongrass >15 times more than in the R population.

The FTIR spectroscopy has been employed in this research work to monitor the process of nitrodope photodegradation, by measuring surfaces of bands typical of a nitro group. Nitric esters are subject to degradation, which is reflected on a quantitative ratio of the surfaces of the IR bands that originate from the nitric ester. The obtained results show that the length of the UV rays activity on the samples over time intervals of 240, 480 and 960 min. directly affects the spectrum appearance of the same sample before and after the radiation. The longer the UV rays activity time and the larger a mass proportion of nitrocellulose in the nitrodope is, the smaller the bands surface becomes i.e. the degree of degradation is higher. To confirm the degradation of nitrodope the degree of reticulation has also been examined by determining the König hardness. U radu je korišćena FTIR spektroskopija za praćenje procesa fotodegradacije nitrolakova, merenjem površina traka koje su karakteristične za nitro grupu. Nitratni estri podležu degradaciji što se odražava na kvantitativni odnos površina IR traka koje potiču od nitratnog estra. Dobijeni rezultati pokazuju da dužina dejstva UV zraka na uzorke u vremenskim intervalima od 240, 480 i 960 min., direktno utiče na izgled spektra istog uzorka pre i posle zračenja. Što je duže vreme dejstva UV zraka kao i maseni udeo nitroceluloze u nitrolaku površina traka se sve više smanjuje tj.stepen degradacije je veći. Za potvrdu degradacije nitrolakova praćen je i stepen umreženosti određivanjem tvrdoće po König-u.

During cheese making process milk components proceed into cheese and whey Their utilization is unequal. The amount of the dominant milk components that proceed into cheese and whey is expressed by their distribution. Proteins and milk fat mostly proceed into cheeses and increase their nutritive and energetic values. In traditional cheese making process, about 20% of total proteins cross into whey. Due to this fact, milk proteins during cheese making are always better utalized. Permanent trends in obtaining new technological solutions for better utility of total milk solids are present. A possible way for better utilization of total milk solids and higher yield acquirement is the use of severe heat treatments. Chemical complex between caseins and whey proteins is formed during severe heat treatments. These chemical complexes are known as coaggregates. Due to their formation, better yield and better nutritive value of cheese is obtained. The cheese making process based on coaggregates formation has several technological problems. Also, due to the presence of whey proteins during aging, these cheeses have specific sensory properties. This work discusses the degree of milk solid utilization during semi-hard cheese based on coaggregates production. According to our results, high degree of milk components distribution into cheese is obtained. The average milk fat and total nitrogen content was 92.15% and 90.97%, respectively. Maximum distribution of total milk solids into cheese was 58.89%, which is significantly higher in relation to the traditional cheese making process. U tradicionalnoj proizvodnji sireva oko 50% suve materije mleka odlazi sa surutkom, pri čemu se pored laktoze, gubi i oko 20% ukupnih azotnih materija koje predstavljaju biološki najvrednije proteine, kao i deo mlečne masti. Zbog toga je uvek postojala težnja za pronalaženjem novih tehnoloških postupaka u proizvodnji sireva, koji bi omogućili potpunije iskorišćenje suve materije mleka i veći randman sireva. jedan od načina jeste primena oštrijih termičkih tretmana mleka, pri čemu dolazi do obrazovanja koagreagata proteina mleka, odnosno hemijskog kompleksa između kazeina i serum proteina. U radu je ispitivan stepen distribucije sastojaka mleka u sir, proizveden od mleka u kojem su obrazovani koagregati proteina mleka, i surutku. Praćen je stepen distribucije: suve materije, suve materije bez masti (SMBM), mlečne masti i ukupnog azota nakon proizvodnje sira. Stepen distribucije ukupne suve materije mleka u surutku je u proseku iznosio 42,63%, a suve materije bez masti 56,38%, dok je u sir u proseku prešlo 57,37% suve materije mleka i 43,62% suve materije bez masti. Distribucija mlečne masti iz mleka u sir bila je visoka i u proseku je imala vrednost 92,15%, sa granicama variranja 89,21-94,76%. Stepen distribucije azotnih materija iz mleka u sir je vrlo visok i u proseku je iznosio 90,97%, a u surutku je u proseku prešlo samo 9,03% azotnih materija mleka, što navodi na pretpostavku da najveći deo azotnih materija surutke čini neproteinski azot. U poređenju sa polutvrdim sirevima, izrađenim na tradicionalan način, može se zaključiti da je stepen distribucije suve materije mleka u sir proizveden na bazi koagregata proteina mleka znatno veći, pre svega zbog većeg stepena iskorišćenja sadržaja mlečne masti i azotnih materija mleka.

Soymilk and tofu are traditional and important source of protein in Asian diets. Soymilk is a watery extract of full-fat soybean. Tofu is a nutritional, protein gel, a kind of soybean product. Yield and quality are affected by several factors, such as variety or cultivar, soybean growth environment and processing methods. Processing factors, which affect the quality of soymilk and tofu, include soaking time and temperature, grinding temperature, soy milk heating rate, stirring speed, type and concentration of coagulant, method of adding coagulant to soy milk, and the weight and time of press. Traditionally prepared soymilk has bean-like flavour owing to lipid oxidation catalyzed by lipoxygenase during soaking and grinding. This flavor is unacceptable to most consumers and is the major obstacle to widespread acceptance of almost all soy food products, especially soymilk and tofu. A steam-infusion cooking process, known as hydrothermal cooking (HTC), was developed to produce soymilk continuously from ground full-fat soy flour. HTC-processed soymilk had less bean-like flavour because of the much shorter time for lipoxygenase to be active and because of the steam flashing stripped volatiles. Coagulation properties of soymilk are critical to achieving high yields and desired texture of tofu. Magnesium or calcium chloride was the most commonly used coagulating agent. The objectives of the present study were to research the effects of HTC processing conditions (at 0.8 bar above the atmospheric pressure; at temperature 110°C; during 8 minutes) and coagulation of soymilk protein with proteinases - himosin and pepsin on yield and quality of soymilk and tofu. Tofu prepared from Lana cultivar expresed the most acceptable sensory characteristics, while the chemical properties were registered for tofu prepared from ZPS-015. Sojino mleko je vodeni ekstrakt celog semena soje, a tofu je želirani proteinski proizvod koji se dobija koagulacijom zagrejanog sojinog mleka. Tradicionalnim načinom proizvodnje dobija se sojino mleko i tofu karakterističnog - leguminoznog mirisa i ukusa. Naša istraživanja imaju za cilj pripremu sojinog mleka i tofua od domaćih sorti soje (tri različita kultivara: Nena, ZPS-015 i Lana) modifikovanim načinom pripreme. Drobljenje i kuvanje namočene soje vršeno je pod nadpritiskom (0,8 bar), visokom temperaturom (110°C) i kratko vreme (8 min; hidrotermičko kuvanje - HTC). Nije korišćena tradicionalna metoda koagulacije sojinog mleka (dodatak CuSo4 ili MgCl2), već proteolitički enzimi - himozin i pepsin. Uočava se veliki stepen iskorišćenosti i izuzetna ekonomičnost sorte soje ZPS-015, gde je prinos tofua skoro 100%. Naime, od 1kg sojinog zrna dobija se 1,93 kg tofua dok je prinos sojinog mleka izjednačen kod sve tri sorte (6,63-6,71L mleka/kg sojinog zrna). Tofu pripremljen od soje sorte Lana može se okarakterisati kao izuzetno hranljiva i kvalitetna namirnica u svakodnevnoj i dijetetskoj ishrani obzirom na bogat sadržaj proteina (13,08%), visokih ocena senzornih karakteristika (srednja ponderisana ocena 4,63; srednja ocena za miris i ukus 4,7) i na to da je ovo varijetet selekcionisan bez Kunicovog tripsin inhibitora koji, ukoliko nije izbalansiran, može imati nepoželjnu antinutritivnu aktivnost. Proteinski proizvodi pripremani ovim načinom proizvodnje (sojino mleko - 15,72-16,61% i tofu - 13,08-15,59) sadrže znatno više ukupnih proteina nego komercijalni (mleko - 4,40%; tofu - 8,10-8,86%).

In the course of the pasteurization treatment of milk and dairy products the temperature of the technological process is kept at a constant value. The regulation of the temperature is carried out by means of technological water that comes from certain pools cooled to the temperature of 5ºC. the water heated in the process of pasteurization is sent back through steel pipes to the pool where it is cooled to the working temperature. the pools for water cooling are fitted with a bundle of pipes made of plain carbon steel that corrode over the time. the protection of pipes against corrosion is possible to be performed in two ways: by use of inhibitors and by cathodic protection. The application of either method depends on a number of factors. It is cheaper to protect new pipes from corrosion using inhibitors, whereas pipes already attacked by corrosion are more efficiently protected against further corrosion by applying the cathodic protection. U toku postupka pasterizacije mleka i mlečnih proizvoda temperatura tehnološkog procesa održava se na konstantnoj temperaturi. Regulacija temperature se vrši pomoću tehnološke vode koja dolazi iz bazena rashlađena do temperature od 5°C. zagrejana voda iz procesa pasterizacije vraća se cevima u bazen gde se pomoću tečnog amonijaka hladi do radne temperature. U bazenima za hlađenje tehnološke vode nalazi se snop cevi od običnog čelika kroz koji prolazi tečni amonijak, a koje vremenom počinju da korodiraju. Zaštita cevi od korozije je moguća na dva načina: primenom određenih inhibitora korozije i primenom katodne zaštite. Koji će od ova dva načina da bude primenjen zavisi od više faktora. Za nove cevi je jeftinija zaštita od korozije primenom inhibitora. za cevi koje su već u upotrebi ili je kod njih počela korozija, primena katodne zaštite je efikasniji postupak dalje zaštite od korozije.

Institute for Food Technology and Biochemistry, Faculty of Agriculture Belgrade Rheological characteristics of cheese influence sensory properties especially consistency of cheese. Elastic properties are based on protein matrix and mineral complex in cheese. Viscous properties are based on water partly milk fat and proteins which pass into soluble form. The curd elasticity, which depends on mineral matter content, is a significant factor for hole formation in cheese that is characteristic for some cheese varieties, such as Emmental, Gouda, Trapist etc. During cheese production calcium content is in correlation with pH value of cheese, which influences rheological properties of cheese (elastic and viscous properties). Chemical composition, especially water, protein and calcium content, as well as pH value, have great influence on rheological properties of cheese. The initial acidity of cheese in- fluences biochemical changes during cheese ripening. This is why acidity is used as parameter of technological production process and attained ripening grade. Complex changes which lead to desirable sensory and rheological cheese characteristics occur during cheese ripening. Considering great influence on rheological properties of cheese, titrable acidity dynamics and mineral matter content, during ripening of cheese based on milk protein coaggregates, were investigated in this research. pH value of experimental cheese in researched period was 5,55-5,08, and titrable acidity was 112,70-229,50oT, respectively. Comparing to literature data, it could be concluded that pH value of experimental cheese had reduction trend during ripening. After 4 months of ripening, pH value was lower, comparing to Dutch type cheeses made traditionally. Low pH value influenced on changed texture of experimental cheese, which did not have significant plasticity. Calcium content after production was 24,12 mg/g of proteins, and after 2 months of ripening 26,80 mg/g of proteins, respectively. Lower content of Ca/g of proteins in experimental cheeses, comparing to cheeses made traditionally, is consequence of modified production of these cheeses, low pH value at milk coagulation, above all. Comparing to semi-hard cheeses made traditionally experimental cheeses are differ by their sensory and rheological characteristics. Reološke karakteristike sira imaju značajnog uticaja na senzorna svojstva, a posebno na konzistenciju sireva. Nosioci elastičnih svojstava su proteinski matriks i mineralni kompleks u siru, a nosioci viskoznih svojstava su voda donekle mlečna mast i deo proteina koji je prešao u rastvorljivi oblik. Elastičnost sirnog testa, koja zavisi od sadržaja mineralnih materija je značajan faktor za obrazovanje šupljika u siru, koje su karakteristične za pojedine vrste sireva kao što su Ementalski, Gauda, Trapist i dr. Pri proizvodnji sireva, sadržaj Ca u siru je u korelaciji sa pH vrednošću sira što se odražava na njegove reološke karakteristike (elastična i viskozna svojstva). Na reološke osobine sira veliki uticaj ima njegov hemijski sastav a poseban značaj ima sadržaj vode, proteina, kalcijuma, kao i pH vrednost. Početna kiselost sireva u velikoj meri utiče na dalji tok biohemijskih promena tokom zrenja sira. Upravo zbog toga kiselost sireva se koristi kao jedan od pokazatelja načina vođenja tehnološkog procesa izrade sira i dostignutog stepena zrenja. Tokom zrenja dolazi do složenih promena, koje dovode do stvaranja željenih senzornih, kao i reoloških karakteristika sira. U okviru ovih istraživanja praćena je dinamika kiselosti tokom zrenja polutvrdih sireva izrađenih na bazi koagregata proteina mleka, kao i sadržaj mineralnih materija, s obzirom na veliki uticaj na reološke osobine sira. U ispitivanom periodu pH vrednost oglednog sira kretala se u intervalu 5,55-5,08, a titraciona kiselost 112,70- 229,50oT. U poređenju sa literaturnim podacima može se konstatovati da je pH vrednost oglednog sira imala trend sniženja tokom perioda zrenja. Nakon 4 meseca zrenja pH je bio niži u poređenju sa sirevima holandskog tipa, koji se izrađuju na tradicionalan način, što je uticalo na izmenjenu teksturu oglednog sira, koji nije imao izraženu plastičnost. Sadržaj Ca nakon proizvodnje imao je prosečnu vrednost 24,12 mg/g proteina, a nakon zrenja od 2 meseca 26,80 mg/g proteina. Manji sadržaj Ca/g proteina u oglednim sirevima u poređenju sa sirevima izrađenim na tradicionalan način posledica je modifikovanog načina izrade ovih sireva, pre svega zbog niske vrednosti pH pri koagulaciji mleka. U poređenju sa polutvrdim sirevima, izrađenim na tradicionalan način, ogledni sirevi se bitno razlikuju kako po svojim senzornim, tako i po reološkim karakteristikama.

Lactic acid bacteria strains isolated from autochthonous cheeses were researched. In products such as these, where starters were not added fermentation occurs as a result of natural flora present in the surrounding environment. Thirty thermophilic, mesophilic and citrate+ LAB strains were isolated by selective medium (LM17 agar and LDC agar) from 5 samples of autochthonous cheeses. They were exposed to further analysis and identification. After examination by Gram test and catalase test, 12 strains of LAB, were selected for further analysis. On the basis of lactose fermentation and acid production in 1% reconstituted skim milk, 6 homofermentative strains were selected, that also had good acidogenic activity. Their proteolytic ability to hydrolyze B-casein was examined by SDS polyacrilamid electrophoresis, where these strains showed different proteolytic activity. Determination of these strains by API Rapid ID 32 Strep tests showed that 4 strains belong to the Lactococcus lactis ssp. tech's and 2 strains to the Lactococcus lactis ssp. lactis biovar. diacetylactis. Rad je obuhvatio karakterizaciju bakterija mlečne kiseline izolovanih iz autohtonih sireva proizvedenih na tradicionalan način, bez dodavanja starter kultura. Iz 5 uzoraka sira izvršena je izolacija 30 termofilnih mezofilnih i cit-rat+ sojeva BMK na odgovarajućim selektivnim podlogama (LM17 agar i LDC agar). Od izdvojenih čistih kultura, nakon određivanja Gram reakcije i katalaza testa, izabrano je 12 sojeva za dalja ispitivanja. Na osnovu načina fermentacije laktoze (homo-heterofermentacija)i acidogene sposobnosti praćene u 1% rekonstituisanom obranom mleku u toku 24 sata, selekcionisano je 6 sojeva koji su pokazali homofermentativnu aktivnost i dobru acidogenu sposobnost. Za ove sojeve je ispitana proteolitička aktivnost u odnosu na β-kazein, pomoću SDS poliakrilamidne elektroforeze, koja je pokazala međusobne razlike u sposobnosti razgradnje β-kazeina. Na kraju je izvršena njihova identifikacija pomoću API Rapid ID 32 Strep testa za laktokoke, i utvrđeno je da 4 soja pripadaju vrsti Lactococcus lactis ssp. lactis, a dva soja vrsti Lactococcus lactis ssp. lactis biovar. diacetylactis.

The use of more severe heat treatment of milk (temperatures higher than 85°C for 10 min. and longer) in cheese making production cause the formation of chemical complex between casein and serum proteins. These complexes are known as co aggregates of milk proteins. Due to the complex formation, serum proteins are incorporated in curd. Obtained cheese has different texture and taste in relation to traditional cheeses. The research has shown that except for the protein-protein complex formation, the interaction between proteins and adsorption layer of fat globules also occurred. Consequently fat globules are not only physically incorporated in protein matrix. Due to this, low content of fat crosses into the whey. One of the major preferences obtained during co aggregates formation are higher degree of milk protein and fat utilization, higher yield, and higher biological value of cheese. In this work, the change of yield and weight loss during different phases of production (after pressing, salting, and ripening) of semi-hard cheese based on co aggregates has been researched. Yield of experimental cheese after pressing was 14.52%, while after salting was 14.17%. During the ripening (15, 30, 60 and 120 days) the yield decreased. The average values were 12.26%, 12.03%, 11.89% and 11.58%, respectively. During experimental cheese production the higher yield in relation to the traditional cheese making process has been obtained. Primena oštrijih termičkih tretmana mleka (na temperaturama višim od 85°C, u dužem vremenskom periodu, 10 minuta i duže), namenjenih za proizvodnju sira u poređenju sa termičkim tretmanima koji se primenjuju pri tradicionalnom načinu proizvodnje, dovodi do formiranja hemijskog kompleksa između kazeina i serum proteina, koji su u literaturi označeni kao koagregati proteina mleka. Usled toga dolazi do inkorporiranja serum proteina u gruš, a dobijeni sir se razlikuje od tradicionalnih sireva, kako po teksturi sirnog testa tako i po ukusu. Istraživanja su pokazala da, pod uticajem visokih temperatura, osim proteinskih interakcija dolazi i do interakcije između serum proteina i adsorpcionog sloja masnih kapljica, tako da masne kapljice nisu samo fizički uklopljene u proteinski matriks, već postoji i jedan vid njihove hemijske interakcije sa proteinima. Na taj način je znatno manji prelazak masti u surutku za vreme obrade gruša. Jedna od velikih prednosti obrazovanja koagregata proteina mleka jeste veći stepen iskorišćenja proteina mleka, mlečne masti, veći randman, a iskorišćenjem proteina surutke povećava se i biološka vrednost sireva. U radu je ispitivana pramena randmana i kala polutvrdog sira proizvedenog na bazi koagregata proteina mleka (ogledni sir) i to u različitim periodima: nakon presovanja, soljenja i u različitim periodima zrenja od 15, 30, 60 i 120 dana. Randman oglednog sira nakon presovanja je u prošeku bio 14.52%, a nakon soljenja 14.17%. Tokom zrenja (15, 30, 60, 120 dana) vrednost randmana oglednog sira se smanjivala i u prošeku je iznosila 12.26%, 12.03%, 11.89% i 11.58%. U poređenju sa polutvrdim sirevima proizvedenim na tradicionalan način, ostvareni randman oglednog sira je imao znatno veće vrednosti.

Gel is defined as "firm" colloid system with coherent structure formed by particles in which water phase is incorporated. According to modern terminology, gel is a high elastic solid system; depending on circumstances these systems flow as viscous liquid, or behave as an elastic solid. Acid casein gel is a particle gel formed from cluster aggregates. These aggregates then interact with each other and form a continual network. As a result of acidification, the charge neutralization occurs and the casein micelles aggregate into clusters and chains incorporated in gel network. Knowing the mechanism of aggregation is very important for understanding effects of factors which influence textural properties of final product. The structure of acid milk gel is dependent upon factors like protein concentration, heat treatment of milk, temperature of incubation or acidification and medium of acidification. Acid casein gel is high elastic material. Due to this fact dynamic and stress relaxation are applied as rheological characteristics measurements. Dynamic measurements and stress relaxation are measured by viscosimeter while the rheometer with constant density is used for creep measurements. Dynamic test is defined with modulus of elasticity (G’) modulus of viscosity (G"), dynamic vicosity (Pas) and complex modulus (G*). The ratio G"/G’ is tan δ. In the case of ideal elastic solid this parameter is 0, and applied density is in phase with deformation. In the case of ideal fluid δ is π/2 and density is completely out of the phase of deformation, but in the phase with the deformation velocity. The increase of viscosity causes an increase of tan δ, while the increase of elasticity reduces this parameter. Also, it could be concluded that tan δ is ideal parameter for fluid (milk)/solid (gel) transformation observing. The gel firmness increases with the increase of protein content, heat treatment and the temperature used during acidification, as well with the decrease of pH. Gel se definiše kao "čvrsti" kolodni sistem u kojem koloidne čestice učestvuju u koherentnoj strukturi u koju je ukomponovana vodena faza. Prema modernoj terminologiji, gel se definiše kao viskoelastični čvrsti sistem koji u zavisnosti od okolnosti teče kao viskozna tečnost ili se ponaša kao elastično čvrsto telo. Kiseli kazeinski gel se ubraja u čestične (partikularne) gelove, koji su izgrađeni od grozdova agregiranog materijala koji zatim formiraju kontinuiranu mrežnu strukturu. Nakon acidifikacije micele kazeina agregiraju usled neutralizacije naelektrisanja pri čemu dolazi do formiranja lanaca i grozdova u mreži. Poznavanje mehanizma agregacije je važno za razumevanje faktora koji utiču na finalnu teksturu konačnog proizvoda. Na strukturu kiselih mlečnih gelova utiču mnogi faktori, među kojima su koncentracija proteina, termički tretmani mleka, temperatura inkubacije ili acidifikacije i izbor sredstva za acidifikaciju. Osnovni gradivni materijal kiselog kazeinskog gela su agregati različitih veličina koji se sastoje od povezanih kazeinskih micela (čestica). Tokom formiranja gela, ovi agregati se spajaju u manjem ili većem stepenu, formirajući na početku kratke grozdove. Ovi grozdovi zatim rastu u dužinu formirajući mrežu. Kiseli kazeinski gel se ponaša kao viskoelastični materijal, pa se za merenje reoloških osobina primenjuju dinamička merenja, merenja napona relaksacije i merenje puženja. Dinamička merenja i merenje napona relaksacije, izvode se pomoću viskozimetra, dok se merenje funkcije puženja vrše na reometru sa konstantnim naponom. Dinamički test je definisan sledećim karakteristikama modul elastičnosti - G’ modul viskoznosti - G" dinamički viskozitet (Pas) kompleksni modul - G*Tan δ je odnos modula viskoznosti i modula elastičnosti (tan δ=G"/G’). U slučaju idealno elastičnog tela, δ je jednak nuli, a primenjeni napon je u fazi sa deformacijom. Za idealno viskoznu tečnost δ=π/2 i napon je potpuno van faze sa deformacijom, ali je u fazi sa brzinom deformacije. Sa povećanjem viskoznih svojstava povećava tan δ, dok se povećanjem elastičnih svojstava smanjuje tan δ. Takođe, može se zaključiti da je tan δ idealan parametar za praćenje promene iz viskoznog tečnog (mleko) u čvrsto (gel) stanje. Primena malog napona na kiseli kazeinski gel, rezultira izduživanjem proteinskog matriksa (koje ima povratnu reakciju); ukoliko se napon poveća iznad napona popuštanja (slamanja strukture), veze u matriksu se lome. Čvrstoća gela se povećava sa povećanjem sadržaja proteina, termičkim predtretmanom mleka, povećanjem temperature pri kojoj se dodaju kiseline ili sredstva za acidifikaciju, i sniženjem pH vrednosti.

Enzyme induced coagulation of milk is one of the oldest technological operations used in cheese making. Chymosin-induced coagulation could be considered as two-stage process. The first stage is hydrolysis of κ-casein. In the second stage, in the presence of Ca2+-ion hydrolyzed casein micelles interact with each other and form a gel. Several factors including casein concentration, pH of milk, Ca2+-ion concentration, temperature of coagulation and parameters of preliminary milk treatment, have influence on both phase of milk coagulation and rheological properties of curd. Ion species as well as their concentration have important influence on hymosin-induced coagulation of milk. Also, especially significant factor of both stages of coagulation is acidity of milk. The increase pH of milk causes velocity increase of enzymatic (first) phase of rennet-induced coagulation. Maximum values could be obtained at pH 6.0. Preliminary heat treatments of milk cause the denaturation of whey proteins and formation of aggregates. Thus, the duration of gelling is longer and decreases the velocity of hardness process. As a result, gel with better properties is formed. This gel is characterized with lower syneresis and better crosslinking. Besides the effects on microorganisms, the use of high temperatures has influence on physico-chemical and technological properties of milk. During the storage of milk several physico-chemical, biochemical and microbiological changes occur. These changes have effect on longer duration of rennet- induced coagulation and lower yield. Milk fat separation process and homogenization have influence on initial coagulation velocity. Na primarnu i sekundarnu fazu koagulacije mleka i reološke osobine gruša utiče veći broj faktora od kojih su najznačajniji: koncentracija kazeina, pH mleka, koncentracija enzima, koncentracija kalcijumovih jona, temperatura koagulacije, kao i režim prethodne termičke obrade mleka. Vrsta i koncentracija jona u velikoj meri utiče na brzinu koagulacije mleka pod dejstvom himozina. Pored kalcijumovih jona, i drugi joni imaju uticaja na koagulaciju mleka kojem je dodat himozin. Od ostalih faktora, koji su značajni za enzimsku fazu, ili fizičko-hemijsku fazu koagulacije mleka, od posebnog značaja je kiselost odnosno pH mleka. Sniženjem pH vrednosti mleka povećava se brzina enzimske faze koagulacije mleka sirilom i postiže maksimum pri pH 6.0. Istraživanja su pokazala da termički tretmani, koji se koriste u tehnologiji mleka, imaju velikog uticaja na primarnu i sekundarnu fazu koagulacije mleka sirilom. Prethodni termički tretmani, koji izazivaju denaturaciju serum proteina i obrazovanje koagregata, produžavaju vreme obrazovanja gela i smanjenje brzine njegovog očvršćavanja. Kao rezultat ovoga obrazuje se finiji gel, koji karakteriše slabiji sinerezis i veća umreženost. Uticaj niskih temperatura na mleko ogleda se na različite fizičko-hemijske biohemijske i mikrobiološke promene, koje imaju za posledicu produženje vremena koagulacije pod dejstvom sirila i manji randman sireva. Tehnološke operacije separiranje mlečne masti i homogenizacija utiču na povećanje brzine koagulacije u momentu kada ona počne.

The influence of the treatment duration and steam pressure on inactivation of biologically active components is presented in this paper. Steaming of cracked soya bean grains used for the protein isolate preparation of efficiently inactivated trypsin inhibitors (TI). Residual activity of Kunitz inhibitor was only detected (2.59-1.70%). The most suitable properties for utilisation in food technology were found for soya bean protein isolate (SPI) prepared from cracked soya bean grains hydrothermally treated for 10 minutes, using steam pressure of 1.5 bar. Such SPI contained 12.34% of residual TI activity, and compared to the untreated sample it contained similar levels of lectin (0.29%) and phytic acid (1.88%). Primena soje i proizvoda na bazi proteina soje ograničena je prisustvom komponenti sa antinutritivnim dejstvom, poput inhibitora proteinaza fitinske kiseline, lektina. Prisustvo ovih komponenti prouzrokovalo je potrebu za iznalaženjem optimalnih rešenja za poboljšanje kvaliteta proizvoda od proteina soje. Cilj ovog rada bio je da se ispita uticaj na promenu aktivnosti biološki aktivnih komponenti proteinskog izolata lomljenog sojinog zrna nakon produvavanja vodenom parom (pri nadpritisku 0,5 bar) u kraćim vremenskim intervalima (5, 10 i 15 minuta). Nakon primenjenog hidrotermičkog tretmana zapaženo je znatno smanjenje tripsin inhibitorske aktivnosti (TIA) sa 72,34% za netretirani proteinski izolat na 6,55% za izolat nakon 15-ominutnog tretmana, pri čemu je nosilac TIA Kunitz-ov tripsin inhibitor (TI) (2,59-1,70%), dok je Bowman-Birk-ov inhibitor registrovan samo kod izolata od netretiranog lomljenjog sojinog zrna (3,92%). SDS elektroforezom je ustanovljena promena u prisustvu lektina kod izolata dobijenih od tretiranih uzoraka (0,77-0,21%) u poređenju sa izolatom dobijenog od netretiranog zrna (1,96%). Rezultati ukazuju da sadržaji ukupnog rastvorljivog fosfora (11,35-5,96 mg P/g), fitinskog fosfora (1,09-0,53%) i fitinske kiseline (1,88-3,87%) pri ovako kratkotrajnim tretmanima (5, 10 i 15 min) nisu u direktnoj zavisnosti od dužine tretmana.

Serum proteins present 18–20% of total milk nitrogen components. β-laktoglobulin (β-lg), α-laktalbumin (α-la), bovine serum albumin (BSA) and immunoglobulins (Ig) are the most important milk serum proteins. Also, milk serum contains low percent of other nitrogen components such as lactoferrin lactolin, glycoprotein, blood transferrin, proteose-peptone fraction (PP). β-lactoglobulin is the major milk serum protein. It is composed of 18300 Da molecular weight monomers. Molecule of β-lactoglobulin has two disulfide bonds, free –SH group at 121position. At pH near isoelectric point exists as a dimmer (M.W. about 36000). At pH 3.5–5.2 β-lactoglobulin expresses reversible tetramer-octamer association. These aggregates are based on hydrophobic interaction. At pH 3.7–6.5, these molecules aggregate as octamer. α-lactalbumin presents 20% of serum proteins or 2–5% of total milk nitrogen components. Molecular weight of α-lactalbumin is relatively small (14000). α-lactalbumin expresses high affinity to different ions especially to Ca- ions. The primary structure is characterized with 121 amino acid residues, high content of sulphur,, four disulphide bonds. There are no free –SH groups, phosphoric groups. The mechanism of serum protein precipitation depends on several factors: pH, temperature level ionic strength, dry matter, lactose content. These factors influence the degree of precipitation, weight of aggregates, the degree of major proteins denaturation as well as the nature of coagulum. U ukupnim azotnim materijama mleka, serum proteini učestvuju sa 18–20%. Najvažnije proteine mlečnog seruma čine β-laktoglobulin (β-lg) α-laktalbumin (α-la), goveđi serum albumin (BSA) i imunoglobulini (Ig). Pored ovih proteina, u mlečnom serumu prisutne su u malim količinama i druge azotne materije, kao što su laktoferin, laktolin, glikoprotein, krvni transferin, kao i proteozo-peptonska frakcija (PP). β-laktoglobulin je najviše zastupljen protein u mlečnom serumu, molekulske mase 18300 po monomeru. Molekul sadrži dva disulfidna mosta i jednu slobodnu sulfhidrilnu grupu na poziciji 121. Pri pH vrednosti blizu izoelektrične tačke β-laktoglobulin se nalazi u obliku dimera, čija je molekulska masa oko 36000. U pH intervalu 3.5–5.2, β-laktoglobulin reverzibilno obrazuje tetramer/oktamer asocijate, u kojima dominiraju hidrofobne interakcije. U pH intervalu 3.7–6.5, β-laktoglobulin obrazuje oktamere. α-laktalbumin čini 20% ukupnih serum proteina, ili 2–5% ukupnih azotnih materija mleka. Ima relativno malu molekulsku masu, 14000, i izražen afinitet prema različitim jonima, naročito prema kalcijumu. Primarnu strukturu karakteriše prisustvo 123 aminokiselinska ostatka, visok sadržaj sumpora, prisustvo četiri disulfidna mosta i odsustvo slobodnih tiolnih i fosfornih grupa. Mehanizam precipitacije serum proteina zavisi od više faktora: pH, visine temperature i dužine njenog delovanja, koncentracije dvovalentnih katjona, pre svega kalcijuma, jonske jačine sredine, sadržaja suve materije i sadržaja laktoze odnosno šećera. Ovi faktori utiču na obim precipitacije, veličinu obrazovanih agregata, stepen denaturacije između denaturisanih molekula α-laktalbumina i β-laktoglobulina, kao i na karakter obrazovanog koaguluma.

The aim of this paper was to examine cholesterol content in meat of five Cyprinidae species: white bream (Bllica bjoerkna L.), carp bream (Abramis brama L.), baltic vimba (Vimba vimba carinata Pallas), zope (Abramis balerus L.) and crucian carp (Carassius carassius gibelio Bloch) from the river Danube. Cholesterol content was examined in the function of season factor and individual weight. Cholesterol concentration in meat of white bream carp bream, baltic vimba, zope and crucian carp is on average level below 20 mg/100 g of meat, which makes meat of these fish species nutritively very valuable. Cholesterol content is variable during the season. Its concentration in meat and in lipids is lowest during spring, during summer it increases and during autumn decreases, except in meat of white bream. Body weight has influence on cholesterol content when its concentration is expressed as % of cholesterol in lipids. Its content in lipids decreases with increasing of individual weight, except in meat of carp bream. Jedan od najznačajnijih faktora rizika koji dovodi do razvoja ateroskleroze i bolesti srca i krvnih sudova je povišen nivo holesterola u krvi. Stoga je cilj ovog rada bio da se ispita sadržaj holesterola u mesu pet vrsta Ciprinida poreklom iz reke Dunav, u funkciji sezonskog faktora i mase jedinki. Sadržaj holesterola u mesu, svih ispitivanih vrsta riba, je na niskom nivou. Njegova prosečna vrednost tokom perioda proleće-jesen kreće se od 14.85 mg/100g u mesu špicera, do 31.40 mg/100g u mesu krupatice. Sadržaj holesterola, u mesu deverike, plavonosa, špicera i babuške je ispod 20 mg/100g mesa, što su znatno niže vrednosti no u mesu toplokrvnih životinja. Koncentracija holesterola u mesu i u masti najmanja je tokom proleća, tokom leta se povećava, a u toku jeseni smanjuje, osim u mesu krupatice. Masa trupa utiče na sadržaj holesterola u slučaju kada je njegova koncentracija iskazana kao % holesterola u masti. Njegov sadržaj u masti smanjuje se sa povećanjem mase jedinki, osim u mesu deverike.

Infection of maize plants with two different viruses: maize dwarf mosaic potyvirus (MDMV) or sugarcane mosaic potyvirus-strain Yu (SCMV-YU), which produced the same type of symptom, resulted in identical changes in peroxidase activity and changes in the profiles of peroxidase isoenzymes. The peroxidase activity kept changing during infection. An increase in the activity of peroxidase was evident at the early stages of the infection. Very low activity of this enzyme was recorded on the 9th day after inoculation when clear symptoms of virus infection were expressed. The level of peroxidase activity was also dependent on the age of the infected leaves. The change in peroxidase activity was negligible in mature leaves and very pronounced in young fast growing leaves.The isoenzyme profiles of peroxidase investigated in this study, suggested that infection with MDMV or SCMV-YU involved in the senescence reaction was produced by the virus infection. Infekcija biljaka kukuruza virusima mozaične kržljavosti kukuruza ili mozaika šećerne trske-soj Yu, koji prouzrokuju isti tip simptoma, izaziva identične promené u aktivnosti i profilima izoenzima peroksidaze. Aktivnost peroksidaze se menja u toku infekcije sa povećanjem na početku infekcije. Veoma niska aktivnost ovog enzima zabeležena je devetog dana po inokulaciji u vreme kada su ispoljeni jasni simptomi virusne infekcije. Nivo aktivnosti peroksidaze zavisi i od starosti lišća. Promene aktivnosti peroksidaze u listovima završenog rasta su beznačajne, a veoma izražene u listovima intenzivnog rasta. Utvrđeno je postojanje 19 izoenzima različite molekulske mase, čija jačina ispoljavanja u različitim danima po inokulaciji upućuje na to da infekcije ispitivanim virusima izazivaju reakcije karakteristične za starenje biljke.

The change of polypeptide composition of soybean isolates, prepared from samples treated by autoclaving in the aim of trypsin inhibitors inactivation (0.5 bar; 5,10 and 15 min.) was investigated. By densitometric analysis of SDS-PAGE-gels, the composition of soybean isolated protein was determined. According to our results, glycinin showed the highest content among proteins of soybean isolates. Depending on duration of soybeans heating, the percentage of glycinin in resulting isolate was 47.14-53.08%. High content of acidic (30.02-30.98%) and basic (15.12-18.24%) polypeptides of glycinin was registered. High content of a-subunit of P-conlycinin was determined (11.49-8.99%). The presence of Bowman-Birk TI as well as lypoxigenase, was not registered in any of protein isolates. Cilj ovog rada bio je da se ispita uticaj nadpritiska 0,5 bara, radne temperature 96°C u trajanju od 5,10 i 15 minuta u autoklavu na promene polipeptidne strukture dobijenih proteinskih Izolata iz lomljenog sojinog zrna. Potvrđena je termostabilnost molekulaglicinina (47,14-53,08%), i manja stabilnost B-konglicinina (15,31-25,45%). Denzitomelrijska analiza SDS-elektroforegrama ukazuje na izraženu termostabilnost kiselih A1,2,4(27,50-26,31%) i baznih B1,2,3,4(18,24-15,12%) polipeptlda glicinina. Sadržaj a-polipeptida fikonglicinina pokazuje linearnu zavisnost od trajanja primenjenih tretmana (10,92-8,99%). Nakon ovih tretmana zapažena je smanjena tripsininhibitorska aktivnost (TIA), pri čemu je nosilac TIA Kunitz-ov TI (5,00-8,80%), dok je Bowman-Birk-ov inhibitor registrovan samo kod izolata iz netretiranog lomljenog sojinog zrna (3,92%).