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Genetički modificirani probiotici
No full textProbiotici su živi mikroorganizmi koji mogu imati povoljan učinak na zdravlje domaćina u određenim koncentracijama. Istraživanja na genetički modificiranim (GM) probioticima posljednjih desetljeća rastu. Intenzivno se proučava utjecaj GM probiotika na liječenje povišenog kolesterola, zubnog plaka te njihova antikarcinogena aktivnost. Genetički inžinjering omogućio je stvaranje potpuno novih mehanizama probiotika poput onoga u Escherichia coli čija je uloga sekvestracija Shiga toksina iz tijela. Rekombinantni Streptococcus mutans BCS3-L1 pokazao je učinkovitost u liječenju karijesa. Određeni GM probiotici, poput Lactobacillus zeae, pokazali su se učinkovitima u proizvodnji antitijela koja imaju mogućnost djelovanja na patogene, toksine, citokine i druge agense u tijelu. Rekombinantni Lactococcus lactis pokazao se kao rješenje za nedostatak enzima važnih za probavu, a svoju je potencijalnu ulogu pokazao i u liječenju ulceroznog kolitisa. No sva ova istraživanja provedena su na pokusnim životinjama i još se čeka potvrda njihove sigurnosti i efikasnosti u kliničkim istraživanjima na ljudima. Sigurna primjena GM probiotika je jedan od glavnih čimbenika o kojima treba voditi brigu zbog opasnosti za imunološki sustav domaćina.Probiotics are live microorganisms that can have a positive effect on the health of the host. The number of studies on genetically modified (GM) probiotics in recent decades is growing. The influence of GM probiotics on the treatment of elevated cholesterol, dental plaque and their anticancer activity is being intensively examined. Genetic engineering has enabled the creation of completely new probiotic mechanisms, the creation of recombinant probiotics such as Escherichia coli whose role is to sequestrate Shiga toxin from the body. Recombinant Streptococcus mutans BCS3-L1 showed its effect on caries treatment. GM probiotics (for example Lactobacillus zeae) showed positive results in producing antibodies whose main role is to act on pathogens, toxins, cytokines, and other agents in the body. Recombinant Lactococcus lactis might be a solution to the enzyme deficiency and might play a main role in the treatment of ulcerative colitis. All these studies have been carried out on experimental animals and are still waiting for the confirmation of their safety and efficacy in clinical trials on humans. The safe usage of GM probiotics is one of the main factors that should be considered because of its possibility to interact with immune system
Funkcionalne skupine fluorescentnih boja za konjugaciju s proteinima
No full textFluorescencija je pojava u kojoj fluorescentna čestica apsorbira svjetlo određene valne duljine te prelazi u pobuđeno stanje. Dok se fluorescentna čestica nalazi u pobuđenom stanju, dio energije se prenosi na obližnje molekule ili se raspršuje u molekularnim sudarima. Na posljetku, preostala se energija emitira kao foton kako bi se elektron vratio u osnovno stanje. Fluorescentne molekule se mogu podijeliti u tri opće skupine, a to su: biološki fluorofori, kvantne točke te organske boje. Navedene fluorescentne molekule se najčešće koriste prilikom fluorescentnog obilježavanja. Naime, radi se o postupku u kojem se fluorofor kovalentno veže na drugu molekulu, kao što je nukleinska kiselina ili protein. Obično se to postiže koristeći reaktivni derivat fluorofora koji se selektivno veže na funkcionalnu skupinu prisutnu u ciljanoj molekuli. U ovom radu se govori o fluorescentnom označavanju proteina pomoću organskih boja koje se vrši tako da se funkcionalna skupina određene fluorescentne boje veže na odgovarajuću funkcionalnu skupinu proteina, a najčešće su to: primarni amini, karboksilna skupina, sulfhidrilna skupina te karbonilna skupina. Nadalje, u ovom radu se također govori o funkcionalnim skupinama koje se najčešće koriste u službi obilježavanja proteina. Navedeni su primjeri najpoznatijih fluorescentnih boja te je sintetizirana boja 2,8- dietil-5-(4-karboksifenil)-1,3,7,9-tetrametildipirometen (BODIPY-COOH) (1) te njezin reaktivni derivat 5-(4-(N-sukcinimidoksikarbonil) fenil)-1,3,7,9-tetrametil-BODIPY (2). Sintetizirana boja (2) je najčešće korištena boja za konjugaciju sa strukturama koje sadržavaju amine stoga je od velikog značaja u kontekstu biooznačavanja.Fluorescence is a phenomenon in which a fluorophore passes into an excitation state by
absorbing a photon of the light of certain wavelength. While the fluorophore is in the
excitation state, part of the energy is transferred to the adjacent molecules or lost due to
molecular collisions. Ultimately, the molecule returns to its basic state, while emitting energy
as a photon. There are three general groups of fluorescent molecules: biological fluorophors,
quantum dots and organic dyes. The most common use of fluorescent molecules is in
fluorescent labeling. Namely, fluorescent labeling entails the covalent binding of a
fluorophore to another molecule, such as a nucleic acid or a protein. Generally, this can be
accomplished by using a reactive derivative of a fluorophore which is capable of selectively
bind to a functional group present in the molecule of interest. This paper discusses the
fluorescence labeling of proteins using organic dyes. The functional group of a certain
fluorescent dye is linked to the corresponding functional group in the protein, most often of
which are primary amines, carboxyl groups, sulfhydryl groups and carbonyl groups.
Furthermore, this work discusses the various functional groups which are most commonly
used in protein labeling. Also, in this work are listed some of the examples of the most widely
used fluorescent dyes, and the compound 5-(4-carboxyphenyl)-2,8-diethyl-1,3,7,9-
tetramethyldipyrimomethene (BODIPY-COOH) (1) and its reactive derivative 5-(Nsuccinimidoxycarbonyl)
phenyl)-1,3,7,9-tetramethyl-BODIPY (2) have been synthesized. The
synthesized dye (2) is the most commonly used dye for conjugation with amino-containing
structures, therefore it is of great importance in the context of bio-labeling
Evaluation of nurses’ workload in intensive care unit of a tertiary care university hospital in relation to the patients’ severity of illness: A prospective study
No full textBackgrounds: Costs of intensive care reach up to 30% of the hospital budget with workforce expenses being substantial. Determining proper nurse—patient ratio is necessary for optimizing patients’ health related outcomes and hospitals’ cost effective functioning. Objectives: To evaluate nurses’ workload using Nine Equivalents of Nursing Manpower Use Score and Nursing Activities Score scoring systems while assessing correlation between both scores and the severity of illness measured by Simplified Acute Physiology Score II. Design: A Prospective study Settings: Cardiac Surgery Intensive Care Unit of the Clinical Hospital Centre Rijeka, Croatia, from October 2014 to February 2015. This Intensive Care Unit has 3 beds that can be expanded upon need. Participants: The study included 99 patients treated at this Unit during the study’s period. The scores were obtained by 6 nurses, working in 12 h shifts. Methods: Measurements were obtained for each patient 24 h after admission and subsequently twice a day, at the end of the day shift (7 pm) and at the end of the night shift (7 am). The necessary data were obtained from the patient’s medical records. Results: Nursing Activities Score showed significantly higher number of nurses are required for one 12 h shift (Z = 3.76, p < 0.001). Higher scores were obtained on day shifts vs. night shifts. (Nursing Manpower Use Score, z = 3.25, p < 0.001; Nursing Activities Score, z = 4.16, p < 0.001). When comparing Nursing Activities Score and Nursing Manpower Use Score during the week, we calculated higher required number of nurses on weekdays than on weekends and holidays, (Nursing Manpower Use Score, p < 0.001; Nursing Activities Score, p < 0.001). Correlation analysis of Nursing Activities Score and Nursing Manpower Use Score with Simplified Acute Physiology Score II has shown that Nursing Manpower Use Score positively associated with severity of disease, while Nursing Activities Score shows no association. Conclusion: Both scores can be used to estimate required number of nurses in 12-h shifts, although Nursing Activities Score seems more suitable for units with prolonged length of stay, while Nursing Manpower Use Score appears better for units with shorter duration of stay (up to four days). Higher workload measured by Nursing Manpower UseScorescalecanbepredictedwithhigherSimplifiedAcutePhysiologyScoreII.However,withlow Simplified Acute Physiology Score II scores it cannot be assumed that the nursing workload will also be low. Further research is needed to determine the best tool to asses nursing workload in intensive care units
Drosophila melanogaster: modelni organizam za bazična i medicinska istraživanja
No full textT.H.Morgan je početkom prošlog stoljeća počeo koristiti Drosophilu melanogaster kao modelni organizam koji omogućuje relativno lako, brzo, jeftino i kontrolirano znanstveno istraživanje u laboratorijskim uvijetima. Drosophila se koristi i danas kao jedan od najpogodnijih laboratorijskih organizama radi naknadno uočene visoke genske sličnost sa sisavcima. Dva pristupa zaslužna da je Drosophila postala modelni organizam bez premca su: genski probir i genski inženjering (metode integriranja željenih gena u genom). Genski probir primjer je genotipskog pristupa (engl. Forward Genetics), i služi za otkrivanje novih gena koji sudjeluju u određenom procesu, dok metode genskog inženjeringa koriste fenotipski pristup (engl. Reverse Genetics), kojim se definira funkcija novootkrivenh gena. Metode genskog inženjerstva, od kojih je najpoznatiji binarni izražajni sustav, omogućuju vrlo preciznu anatomsku i vremensku kontrolu nad genskom izražajnošću. Upotreba genskog inženjeringa omogućila je definiranje neuralnih mreža koje generiraju ponašanje kroz detaljnu analizu staničnog i ponašajnog fenotipa. Razumijevanje složenih obrazaca ponašanja proteklih je godina značajno uznapredovalo korištenjem optogenetskih pristupa te primjenom metode genskog uređivanja (engl. editing), CRISPR/Cas9. Radi genske homologije sa sisavcima, otkrića na Drosophili, lako se prevode na ostale organizme, te tako dovode do značajnih napredaka u razumijevanju bazičnih mehanizama funkcioniranja i raznih patološka stanja
Extraction and quantification of metabolites from olive leaves obtained from Krk Island and Marčeljeva Draga
No full textEkstrakt lišća masline naširoko je proučavan zbog svog antioksidativnog,
protuupalnog i antimikrobnog učinka te brojnih ostalih protektivnih svojstava, za
koje se smatra da su zaslužne u njemu prisutne fenolne komponente kao što su
oleuropein, 3-hidroksitirosol, tirosol, p-kumarinska kiselina, p-hidroksifeniloctena
kiselina, pinorezinol i mnoge druge. Cilj ovog rada bio je dokazati prisutnost
spomenutih komponenti i usporediti njihovu zastupljenost u maslinovom lišću s
Krka i Marčeljeve Drage, te usporediti utjecaj različitih metoda ekstrakcije na
ukupni sadržaj dobivenog ekstrakta. Korištene su tri metode ekstrakcije krutotekuće
uz: 80%-tni etanol pri 70 °C, 80%-tni etanol pri temperaturi vrelišta (78
°C) i destiliranu vodu pri 90 °C. Za identifikaciju i kvantifikaciju komponenti
korištena je kromatografija ultra visoke djelotvornosti (UHPLC).
Rezultati su ukazali na veću zastupljenost oleuropeina, tirosola, 3-
hidroksitirosola i 3-p-kumarinske kiseline u lišću mladih maslina iz Marčeljeve
Drage, dok je lišće starih maslina s područja Krka imalo veće koncentracije phidroksifeniloctene
kiseline i pinorezinola. 80%-tni etanol se pokazao
najpogodnijim otapalom za ekstrakciju oleuropeina i ostalih fenolnih komponenti
kod ekstrakta iz Marčeljeve Drage, dok su kod maslinovog lišća s Krka dobiveni
kontradiktorni rezultati koji ukazuju na bolje prinose s destiliranom vodom kao
otapalom. Sadržaj ekstrakta nije pokazao značajnu razliku ovisno o temperaturi
pri kojoj je provođena ekstrakcija za većinu fenolnih komponenti, osim kod
oleuropeina u lišću iz Marčeljeve Drage koji je u većim količinama bio prisutan pri
ekstraciji s etanolom pri 70 °C, nego što je bio pri 78 °C. Analiziran je i
komercijalni ekstrakt te je u njemu dokazana prisutnost oleuropeina. Potrebno
je nabaviti druge standarde i provesti analizu spektrometrijom masa kako bi
identificirale ostale prisutne komponente za koje nismo imali potrebne standarde.
Metode ekstrakcije korištene u ovom radu koriste zelena otapala,
jednostavne su, jeftine i daju visoke prinose fenolnih komponenti, zbog čega
pokazuju potencijal za primjenu u farmaceutskoj, kozmetičkoj i prehrambenoj
industriji.Olive leaf extract has been widely studied because of its antioxidative,
anti-inflammatory, and antimicrobial effect, as well as other protective properties
that are believed to be present due to the abundance of components such as
oleuropein, 3-hydroxytyrosol, tyrosol, p-coumaric acid, p-hydroxyphenyl acetic
acid, pinoresinol and many others. This study aimed to prove the presence of
the above-mentioned compounds in olive leaf extracts from two different
geographical origins; Marčeljeva Draga and Krk, and to compair their total
concentrations. The second goal was to compare the effect of three different
solid-liquid extraction methods on total phenolic extract content, for which we
used 80% ethanol at 70 °C and 78 °C, respectively, and distilled water at 90°C.
Ultra-high performance liquid chromatography was used for the identification and
quantifiaction of compounds.
The results showed a higher cocentration of oleuropein, tyrosol, 3-
hydroxytyrosol and p-coumaric acid in young olives leaves from Marčeljeva
Draga, while older olive leaves from Krk had higher concentrations of phydroxyphenyl
acetic acid and pinoresinol. 80% ethanol proved to be the most
suitable solvent for the extraction of oleuropein and other phenolic components
in the extract from Marčeljeva Draga, while the extract from Krk gave
contradictory results; better yields using water as a solvent. The extract content
did not show a significant difference depending on the temperature at which
extraction was performed for most phenolic components, except for oleuropein in
leaves from Marčeljeva Draga, which was present in larger quantities when
extracted with ethanol at 70 °C, opposed to boiling at 78 °C. A commercial olive
leaf extract was also analyzed and the presence of oleuropein was confirmed.
The extraction methods used in this research require green solvents, they
are simple, inexpensive and give high levels of phenolic components, which is
why they show potential for usage in pharmaceutical, cosmetic and food
industries
Antibakterijske aktivnosti kvaternih amonijevih soli
No full textKvaterne amonijeve soli ionski su spojevi općenite strukturne formule NR4
+A-, gdje R+ može
predstavljati alkilnu ili arilnu skupinu, a A- bilo koji anion koji je inače prisutan u solima. Zbog
njihove strukture, kvaterne amonijeve soli široko su korištene u industriji i bolničkom
okruženju za kontrolu bakterijskog rasta u različitim sredstvima za čišćenje, korišteni
samostalno ili dodani nekim drugim antimikrobijalnim sredstvima. U ovom radu predstavit će
se pojam kvaternih amonijevih soli, sinteza kvaternih amonijevih soli, njihov način djelovanja
na bakterijski rast, te kako bi to potencijalno moglo utjecati na sve češće pojavljujuću
rezistenciju bakterija na antibiotike i antimikrobike.Quaternary ammonium salts are ionic compounds, with a characteristic structure NR4
+A-,
where R+ is an alkyl or an aryl group, while A- presents any anion usually found in salts.
Because of their structure, quaternary ammonium salts are widely used in hospitals and the
industry as antimicrobial cleaning products. With their main purpose for control of the growth
of bacteria they can be added to cleaning products or used on their own. In this thesis the
structure of quaternary ammonium salts will be introduced, along with their syntheses, and
the way they affect bacterial growth. The effect of these compounds on the increasing
antibiotic and antimicrobial bacterial resistance will also be discussed
Uloga autofagije kod replikacije herpes simpleks virusa
No full textHerpes simpleks virus je virus sa jedinstvenim sposobnostima latencije i
neuroviruloentnosti. Vaţan faktor strategije koja mu omogućava ovakve jedinstvene
sposobnosti je inhibicija autofagije. Autofagija je proces koji doprinosi homeostazi
stanice u normalnim uvjetima i njezina disfunkcija povezana je sa nizom bolesti poput
osteoartritisa i raka. Kad je stanica u stanju infekcije, autofagija sudjeluje u obrani
stanice od unutarstaničnih patogenih organizama. Mnogi virusi, kako bi pospješili
izglede za uspješnu proliferaciju, prilagodili su se razvijajući proteine koji djeluju na
proces autofagije i moduliraju unutarstanične signalne puteve za regulaciju autofagije
u svoju korist. Herpes simpleks virus razvio je dva proteina koji djeluju na autofagiju:
ICP 34.5 koji je jedan od proteina virusnog tegumenta i koji inhibira autofagiju
direktno, na početku virusne infekcije stanice. Drugi virusni protein,Us11, javlja se
kasnije u infekciji kada je već započela transkripcija virusne DNA, te osigurava da
stanični senzori za infekciju poput protein kinaze R ne pokrenu povećanje razine
autofagije kao odgovor na prisutnu virusnu DNA. Značaj i utjecaj inhibicije autofagije
moţe se uvidjeti u činjenici da HSV-1 bez navedenih proteina rijetko uspijeva
efikasno zaraziti organizam i uspostaviti latentnost.Herpes simplex virus has developed the unique abilities of latency and
neurovirulence. An important contributing factor in the strategy that enables these
unique abilities is the inhibition of autophagy. Autophagy is a process that takes part
in the maintenance of cell homeostasis in normal conditions, a disfunctional
autophagy mechanism is linked to a variety of illneses like osteoarthritis and cancer.
When the cell is undergoing a state of infection, autophagy takes part in the defence
of the cell from intracellular pathogens. Many viruses have adapted to it in order to
improve the chances of successful propagation. These viruses have evolved proteins
which act upon the autophagic process and modulate intracellular signaling in order
to hijack the mechanism of autophagy. The herpes simplex virus has evolved two
proteins which have an effect on autophagy: ICP 34.5 is a part of the viral tegument
and it inhibits autophagy directly at the onset of the viral infection. The other protein is
Us11, which is typically found later during the infection, after transcription of viral
genes and DNA replication has already started. Us11 ensures that the cellular
sensors responsible for detecting foreign viral components in the citosole don`t
trigger autophagy as a response to viral DNA. The importance of autophagy inhibition
on the infection is evident in the fact that HSV-1 mutants lacking the forementioned
proteins can rarely establish neurovirulence and neurolatency
Neuroregeneracija središnjeg živčanog sustava
No full textNeuroregeneracija je proces koji podrazumijeva generiranje novih živčanih stanica i
popravak onih oštećenih. Nažalost, regeneracija središnjeg živčanog sustava (SŽS)
nakon ozljede ili uslijed neurodegeneracije nije moguća kod odraslih sisavaca, pa niti
kod čovjeka, jer su zrele živčane stanice postmitotičke, a proces samoobnove tkiva
sprječavaju različite molekule prisutne u vanstaničnom matriksu i glia stanicama.
Kako se ozljede živčanog sustava i neurodegenerativne bolesti smatraju tihom
epidemijom današnjeg društva, za koje nema učinkovite terapije, posljednjih godina
veliki se napori ulažu kako bi se razumjeli molekularni i stanični procesi koji su
osnova neuroregeneracije.
U ovom radu opisana su novija otkrića na području neuroregeneracije odraslog
središnjeg živčanog sustava sisavaca, te su detaljno opisani negativni i pozitivni
procesi koji na neuroregeneraciju utječu, a kojima bi se moglo manipulirati u
terapeutske svrhe.Neuroregeneration is a process which involves generation of new nerve cells and repair of injured ones. Unfortunately, regeneration of the central nervous system is not possible after injury or neurodegenerative diseases in adult mammals because the mature nerve cells are postmitotic and the process of tissue self-renewal is prevented by the different molecules present in the extracellular matrix and glial cells.
As the injuries of the central nervous system and neurodegenerative diseases are considered to be a silent epidemic in today’s society, with no effective therapy, great efforts have been made in recent years to understand the molecular and cellular processes underlying neuroregeneration.
This paper describes recent findings related to neuroregeneration of the adult mammalian central nervous system and explain negative and positive processes involved in neuroregeneration, which could be targets for the future therapeutic strategies
Novi potencijalni interakcijski partneri:PI3P i protein kinaza A
No full textFosfoinozitidi su skupina unutarstaničnih fosfolipida, koji nastaju iz fosfatidilinozitola (PI) djelovanjem brojnih kinaza i fosfataza. Iako su unutar stanice zastupljeni u maloj količini, njihova metabolička aktivnost ukazuje na veliki biološki značaj u regulaciji staničnih procesa i staničnoj signalizaciji. U ovom radu smo pratili fosfoinozitid 3-fosfat (PI3P), te njegov utjecaj na signalni put cAMP/protein kinazu A (PKA) u staničnoj liniji DAMI, stanicama ranog razvojnog stadija megakariocita. Glavni enzim koji producira većinu PI3P u stanicama je Vps34 kinaza (fosfatidil inozitol 3-protein kinaza klase III). PI3P smo u stanicama pratili transficiranjem DAMI stanica sa zelenim fluorescentnim proteinom fuzioniranim na 2xFYVE domenu (GFP2xFYVE) fluorescentnom mikroskopijom. Prisustvo zelenih vezikula odražavalo je lokalizaciju i prisustvo PI3P u DAMI stanicama. Imunofluorescencijom smo u stanicama pratili i lokalizaciju PKA regulatorne I podjedinice (RI), te smo utvrdili djelomičnu kolokalizaciju PI3P i PKA- RI. DAMI stanice koje eksprimiraju GFP-2xFYVE korištene su kao model praćenja inhibicije Vps34 kinaze, te smo ispitali učinak inhibitora ove kinaze (SAR405) na izgled i lokalizaciju zelenih vezikula PI3P u različitim vremenima. U konačnici, ispitali smo učinak inhibicije Vps34 kinaze i nedostatka PI3P na aktivnost PKA prateći raznu fosforilacije VASP na serinu 239 i 157, citoskeletnog supstrata PKA koji odražava njenu aktivnost. Na temelju dobivenih rezultata utvrdili smo kako postoji interakcija signalnog puta PI3P i PKA u megakariocitičnoj staničnoj liniji DAMI, te se otvaraju nova područja istraživanja kako bi se otkrio značaj i važnost ove nove interakcije.Phosphoinositides are a group of intracellular phospholipids, synthesized from phosphatidylinositol (PI) by a number of kinases and phosphatases. Although phosphoinositides are present in small amounts in cells, their high metabolic activity indicates a great biological significance in cellular regulation and signaling. This study focuses on phosphoinositide 3-monophosphate (PI3P), and its role in the cAMP / PKA signaling pathway in the cell line DAMI, that represents early stages of megakaryocyte development. The main enzyme that produces the majority of PI3P in the cells is Vps34 kinase (phosphatidyl inositol 3-protein kinase class III). Here PI3P was monitored by transfecting DAMI cells with green fluorescent protein fused with 2xFYVE domain (GFP2xFYVE) and by fluorescence microscopy. The appearance of green vesicles reflected the localization and presence of PI3P in DAMI cells. The location of PKA regulatory subunit (RI) was determined in cells by immunofluorescence, and it partialy colocalized with PI3P. DAMI cells expressing GFP-2xFYVE were used as a model for monitoring Vps34 kinase inhibition and we tested the effect of Vps34 kinase inhibitor, SAR405 on appearance and localization of vesicles at different times. Finally, we tested the effect of inhibition of Vps34 kinase on PKA activity, monitoring phosphorylation of VASP on serine 239 and 157, the cytoskeletal substrate of PKA that reflects its activity. Based on the results obtained, we determined an interaction of PI3P and PKA signaling pathways in the DAMI cell line. This opens up new area of research to reveal the significance and importance of newly found interaction
Determination of nitrite and nitrate in meat and meat products
No full textPojavom procesa industrijalizacije i urbanizacije te rasta broja stanovnika javlja se i potreba za povećanom proizvodnjom hrane. Porastom svijesti o zdravoj prehrani velik broj ljudi okreće se hrani prirodnog porijekla koja je, za razliku od većine industrijskih proizvoda, manje tretirana pa je samim time privlačnija opcija. Korištenje dodataka hrani poput aditiva postaje nužno radi očuvanja nutritivne vrijednosti namirnica, poboljšanja njihovih organoleptičnih svojstava te produženja roka trajanja hrane. Najčešće korišteni aditivi poput bojila, antioksidansa, pojačivača okusa i konzervansa prisutni su u gotovo svakom prehrambenom proizvodu, no njihova prisutnost ne označava i smanjenu kvalitetu. Bogatstvo proteina, peptida, masnih kiselina, minerala, vlage i ostalih faktora rasta čine meso i mesne proizvode idealnim za rast mikroorganizama i bakterija te je bez adekvatne pripreme i skladištenja podložno gubitku nutritivnih svojstava i brzom kvarenju.
Konzervansi poput natrijevog nitrita i natrijevog nitrata koriste se u proizvodnji, obradi, pripremi i čuvanju mesnih proizvoda radi održavanja njihovih nutritivnih vrijednosti i postizanja zadovoljavajućeg komercijalnog učinka. S obzirom na prisutnost nitrata u dušičnom ciklusu u prirodi te činjenici da meso, voće, povrće, masti i druga hrana sadrže nitrite i nitrate potrebno je pripaziti na dnevni unos zbog potencijalnih posljedica za zdravlje.
U ovom radu analizirane su koncentracije natrijevog nitrita i nitrata u 59 uzoraka mesa i mesnih proizvoda prikupljenih na području Republike Hrvatske. Uz pomoć metode određivanja nitrita i nitrata putem apsorbancije u području 540 nm (nitriti) i 340 nm (nitrati) izražene su koncentracije te uspoređene s Uredbom Komisije (EU) br. 1129/2011 o izmjeni Priloga II. Uredbe (EU) br. 1333/2008 Europskog parlamenta i Vijeća o popisu EU vezano uz prehrambene aditive. Najveće vrijednosti natrijevog nitrita zabilježene su u skupini toplinski obrađenih kobasica (82 mg/kg) dok su najveće razine natrijevog nitrata zabilježene u skupini trajnih kobasica (241 mg/kg). Analizom je primijećeno da samo jedan uzorak ima nezamjetno veću razinu natrijevog nitrita od zakonom propisane, no može se smatrati sukladnim zakonodavstvu kada se u obzir uzme mjerna nesigurnost primjenjene analitičke metode.With the emersion of processes of industrialization and urbanization along with the increase in population size, rises the need for increased food production. With increased awareness of healthy dieting a large number of people turns to natural food which opposed to most industrial products is less treated so that makes it an alluring option. The use of food supplements, e.g. additives, becomes necessary to preserve nutritional value in food, enhance its organoleptic properties and prolong expiration date. Most commonly used additives such as food dyes, antioxidants, flavour enhancers and preservatives are present in almost every foodstuff but their presence doesn’t signify lower quality of food itself. Abundance of protein, peptides, fatty acids, minerals, moisture and other growth factors make meat and meat products an ideal medium to promote microorganism and bacterial growth. Without proper preparation and storage meat is very susceptible to losing its nutritional value and spoilage.
Preservatives such as sodium nitrite and sodium nitrate are commonly used in production, processing and preserving meat products as to keep its nutritional value and achieving satisfactory commercial impact. Considering the presence of nitrates in nature’s nitrogen cycle and the fact that meat, fruits, vegetables, fat and other food contain nitrates and nitrites it’s necessary to pay attention to daily intake to prevent potential health consequences.
In this study concentrations of sodium nitrite and nitrate were analysed in 59 samples of meat and meat products collected in Republic of Croatia. Using the assessment method for nitrites and nitrates the concentrations were callculated from absorbance at 540 nm (nitrites) and 340 nm (nitrates) wavelength and compared with the Croatian regulations for maximum levels of food additives. The highest cooncentrations of sodium nitrite were found in heat treated sausages (82 mg/kg) while the highest levels of sodium nitrate were found in dry-cured sausages (241 mg/kg). During the analysis it was noted that only one sample had a negligibly higher concentration of sodium nitrite than it is allowed by the regulations but can be considered as compliant to legislation when taking into account the measurement uncertainty of the applied analytical method