Nova istraživanja virulentnosti enterohemoragičnih Esherichia coli u hrani

Most of the genes recently found in pathogenic E. coli encode various factors which directly determine their virulence and pathotype. Two main virulence factors characteristic for enterohemorrhagic E. coli(EHEC) are attaching/effacing lesions and Stx1/Stx2 toxins. Genes responsible for expression of aforementioned virulence factors are heavily regulated by environmental conditions. Low iron concentration induces massive expression of stx1 gene and subsequent toxin synthesis. Stress response of EHEC to starvation, acid challenge, cold shock and osmotic changes which damage DNA, induce 'SOS' response. This response mediated by Rec A protein not only repairs damaged DNA fragments but also induces conversion of lysogenic bacteriophage lifecycle to lytic phase followed by intensive expression of stx2 genes. Bacterial stress adaptation of E. coli to novel technologies and the potential for stress-associated enhanced virulence need to be addressed in more detail to prevent potential risk of disease. An increased understanding of expression of virulence-associated genes will provide information for control of pathogens and increase microbial safety of foods.Većina gena koji su poslednjih godina utvrđeni kod patogenih E. coli kodiraju različite faktore koji direktno utiču na njihovu virulentnost i pripadnost određenom patotipu. Dva glavna faktora virulencije kod enterohemoragičnih E. coli (EHEC)su attaching/effacing lezije Stx1/Stx2 toksini. Geni odgovorni za ekspresiju pomenutih faktora virulencije pod jakim su uticajem uslova sredine. Niska koncentracija gvožđa indukuje jaku ekspresiju stx1 gena i posledičnu sintezu velike količine Stx1 toksina. Stresni odgovor EHEC na manjak hranljivih supstanci, povećanje kiselosti sredine, izloženost hladnoći kao i na promene osmolarnosti, koji oštećuju DNK, indukuje 'SOS' odgovor. 'SOS' reakcija posredovana Rec A proteinom ne samo da popravlja oštećene fragmente DNK molekula, već i pokreće mehanizam konverzije bakteriofaga integrisanog u hromozom E. coli iz lizogene faze u litički ciklus tokom koga dolazi do intenzivne ekspresije stx2 gena. Da bi se preventirao potencijalni rizik nastanka bolesti, neophodno je detaljno proučavati prilagođavanje E. coli novim tehnologijama pripreme i konzervacije hrane i potencijal za stres-indukovanu virulenciju. Dobro poznavanje ekspresije gena odgovornih za virulenciju obezbediće informacije neophodne za kontrolu patogena i povećaće mikrobiološku bezbednost hrane

Determination of staphylococcal enterotoxins in cheese by immunoenzyme assays

Staphylococcal food poisoning is one of the most common foodborne diseases resulting from the ingestion of staphylococcal enterotoxins (SEs) preformed in foods by enterotoxigenic strains of coagulase-positive staphylococci (CPS), mainly Staphylococcus aureus. The presence of enterotoxigenic strains of coagulase-positive staphylococci in raw milk during the production process leads to the contamination of products and outbreaks of alimentary intoxication. The problem of Staphylococcus aureus in cheese remains significant on a global level. Domestic cheese contaminated with enterotoxigenic staphylococci can result in the formation of enterotoxin, which can produce foodborne illness when the product is ingested. Due to microbiological contamination, microbiological criteria are tools that can be used in assessing the safety and quality of foods. In order to avoid foodborne illness, the Serbian Regulation on General and Special Conditions for Food Hygiene (Official Gazette of RS, No. 72/10) provides microbiological criteria for staphylococcal enterotoxins in dairy products

Identification of mycobiota in Serbian slaughterhouses

Mould growth within slaughterhouses is not acceptable and is considered as both economic and aesthetic problem. Aim of this paper was to determine filamentous moulds in two slaughterhouses by investigating air, water, environment area and equipment. There were a total of 100 samples collected. According to S a m s o n (2004), 6 genera were determined among which Penicillium and Aspergillus were the most frequent. Three Penicillium species were identified; the most frequent were P. brevicompactum and P. solitum. The presence of P. verrucosum was not established. The presence of mycotoxigenic moulds, such as P. brevicompactum, indicates possible contamination of environmental area with mycophenolic acid (MPA). Results of investigation indicated that more comprehensive survey should be made in order to get a better insight of mycobiota in slaughterhouses in Serbia

Uticaj smanjenja sadržaja natrijum-hlorida u suvom svinjskom mesu na parameter senzornog kvaliteta i instrumentalno merenu boju

The aim of this paper was to examine sensory properties and instrumentally measured colour of dry pork produced with less amount of sodium chloride. Trial was consisted from five batches, two control and three experimental. Pork from control group was cured with 6% nitrite curing salt (C1 group) and with 3% nitrite curing salt (C2 group), respectively. Pork from 1st experimental group was produced with 2% nitrite curing salt and 1% potassium chloride; pork from 2nd experimental group was produced with 1,5% nitrite curing salt and 1,5% potassium chloride; dry meat from 3rd experimental group was produced with 2% nitrite curing salt and 1% ammonium chloride. Curing process lasted for 7 days; smoking, drying and ripening for 21 days. In final products, water activity, moisture, protein and fat content was determined. Taste was best evaluated in dry pork from C2 group and worst in dry pork from 2nd group. The most expressed saltiness was determined in dry pork from the first control group (C1) that corresponded to the largest amount of added salt. Due to most expressed bitter taste, the evaluation for overall acceptability for dry meat from the second experimental group was the lowest. The evaluation for overall acceptability of dry pork from the first control group was significantly lower in the comparison with the evaluations for dry meat from the second control group (C2) and the first experimental group (P ≤ 0.05).Cilj ovog rada je bio da se ispitaju senzorske karakteristike i instrumentalno merena boja suvog svinjskog mesa proizvedenog sa smanjenim sadržajem natrijum-hlorida. Za potrebe eksperimenta, proizvedeno je pet grupa suvog mesa, od kojih su dve kontrolne. Meso iz prve kontrolne grupe salamureno je sa 6% nitritne soli za salamurenje (C1 grupa), a meso iz druge kontrolne grupe (C2) sa 3%. Meso iz prve ogledne grupe (1) proizvedeno je uz dodatak 2% nitritne soli za salamurenje i 1% kalijum-hlorida; meso iz druge ogledne grupe (2) uz dodatak 1,5% nitritne soli za salamurenje i 1,5% kalijum-hlorida, dok je meso iz treće ogledne grupe (3) proizvedeno sa 2% nitritne soli za salamurenje i 1% amonijum hlorida. Proces salamurenja trajao je sedam dana, a dimljenje, sušenje i zrenje 21 dan. U gotovim proizvodima određivani su aktivnost vode, sadržaj vlage, proteina i masti. Suvo svinjsko meso iz druge kontrolne grupe dobilo je najbolju ocenu za ukus, dok je najnižu dobilo meso iz druge ogledne grupe. Slanost je bila najizraženija u suvom mesu iz prve kontrolne grupe, što je u saglasnosti sa najvećom količinom upotrebljenog natrijum-hlorida. Usled najviše izraženog gorkog ukusa, ocena za ukupnu prihvatljivost suvog mesa iz druge ogledne grupe bila je najniža. Ocena za ukupnu prihvatljivost suvog mesa iz prve kontrolne grupe bila je statistički značajno niža u poređenju sa ocenama za suvo meso iz druge kontrolne grupe (C2) i prve ogledne grupe (P ≤ 0,05)

Dietary Intake of Salt from Meat Products in Serbian Population

Salt intake above 5 g/day correlates with prevalence of hypertension and cardiovascular diseases (CVD). CVD, the leading cause of mortality and morbidity in Europe, account for 45% of all deaths, while, in Serbia in 2021, CVD accounted for 47.3%. The objective was to investigate salt content labelled on meat products from the Serbian market and estimate dietary exposure to salt from meat products in the Serbian population using consumption data. Data on salt content were collected from 339 meat products and classified in eight groups. Consumption data were collected using the EFSA EU Menu methodology (2017–2021) from 576 children and 3018 adults (145 pregnant women) in four geographical regions of Serbia. The highest salt content was in dry fermented sausages and dry meat, average 3.78 ± 0.37 g/100 g and 4.40 ± 1.21 g/100 g, respectively. The average intake of meat products is 45.21 ± 39.0 g/day and estimated daily salt intake from meat products per person is 1.192 g, which is 24% of the daily recommended amount. The actual meat product consumption and content of salt in meat products in Serbia present a risk factor for development of CVD and related comorbidities. A targeted strategy, policy and legislation for salt reduction are needed

Assessment of biogenic amine production by lactic acid bacteria isolated from Serbian traditionally fermented foods

The aim of this study was to monitor the production of biogenic amines by 156 selected lactic acid bacteria (LAB) strains isolated from Serbian traditionally fermented sausages and cheeses. The method for the determination of biogenic amines is liquid chromatography tandem mass spectrometry (LC-MS/MS). The measured concentrations of putrescine, cadaverine, tryptamine and spermidine (except in 13 LAB strains) were below the detection limit of the analytical method (0.1 mg/L), whereas those of histamine, tyramine and spermine were above the limit of detection, but still not significant. Tyramine was the only amine that had a measured concentration of 59.89 ± 0.06 mg L-1. Most of the tested LAB strains produced tyramine in broth below 26 mg L-1 with the exception of Enterococcus faecalis strains (59.89 ± 6.66 mg L-1) and Enterococcus faecium strains (47.33 ± 8.58 mg L-1). The low concentrations of biogenic amines are considered non-significant from both a technological and safety point of view.Publishe

Praćenje promena ukupnog broja mezofilnih bakterija i torimetrijske vrednosti u uzorcima sveže pastrmke upakovane u modifikovanu atmosferu i vakuum

Today, food must be healthy, subjected to minimal processing, and attractively packaged, as the expectations of consumers are ever higher. Consumers are highly sensitive to the use of additives in the food industry. There is a constant demand for fresh food that does not contain any unnecessarily added chemicals. In order to prevent spoilage of food items, an efficient and intelligent concept for preserving freshness has been developed - packaging in a modified atmosphere. Changes in a certain composition of the atmosphere within the packaging have resulted in a longer shelf life and a satisfactory quality of the food articles. Modified atmosphere packaging (MAP) is well-known and has been applied in practice in the food processing industry for more than one century. The objective of these investigations was to determine the growth of the total number of mesophilic bacteria in the meat of trout packaged in a vacuum and a modified atmosphere and torry meter reading results due to changes in the dielectric characteristics of the skin that take place during the period of storage of the fresh fish. California trout (Oncorhynchus mykiss) with an average weight of 293 g was used for the experimental part of the investigations. Four groups of fish samples were set up for the research. The first three groups of samples were packaged in a modified atmosphere with a different ratio of gases: Group I - 60%CO2+40%N2; Group II - 40%CO2+60%N2; Group III - 90%CO2+10%N2. Group IV comprised samples packaged in a vacuum. Investigations were carried out on days 0, 7, 14, and 21 of storage. The total number of mesophilic bacteria in the examined samples was determined according to the method ISO 4833. Measurements of changes in the dielectric characteristics of the fish skin were performed using a torry meter apparatus (The Torry Fish Freshness Meter). The results have shown that packaging of fresh trout in a modified atmosphere (60% CO2 + 40% N2 and 40% CO2 + 60% N2) has an advantage regarding the growth of the total number of mesophilic bacteria and the decreased torry meter readings in comparison with vacuum packaging and packaging with a higher concentration of carbon dioxide (90%).Svest potrošača o zdravoj ishrani danas je na visokom nivou. Potrošači su veoma osetljivi kada je u pitanju upotreba aditiva u industriji hrane. Zahtev je da se, u svakom trenutku, može nabaviti sveža hrana bez nepotrebno dodatih hemikalija. Da bi se sprečio kvar namirnica razvijen je efikasan i inteligentan koncept očuvanja svežine – pakovanje u modifikovanu atmosferu. Promenom određenog sastava atmosfere unutar pakovanja postignuti su duža održivost i zadovoljavajući kvalitet namirnica. Pakovanje u modifikovanu atmosferu (MAP) je poznato i primenjuje se u oblasti prerade namirnica duže od jednog veka. Cilj ovog istraživanja je utvrđivanje rasta ukupnog broja mezofilnih bakterija u mesu pastrmke upakovane u vakuum i modifikovanu atmosferu i kretanje torimetrijske vrednosti usled promena dielektričnih svojstava kože koja se dešavaju tokom perioda skladištenja sveže ribe. Za eksperimentalni deo rada korišćena je kalifornijska pastrmka (Oncorhynchus mykiss) prosečne mase 293 g. Za potrebe istraživanja formirane su četiri grupe uzoraka ribe. Prve tri grupe uzoraka upakovane su u modifikovanu atmosferu sa različitim odnosom gasova: grupa I – 60%CO2+40%N2; grupa II – 40%CO2+60%N2; grupa III – 90%CO2+10%N2. Uzorci grupe IV upakovani su u vakuum. Ispitivanja su rađena nultog, sedmog, četrnaestog i dvadesetprvog dana skladištenja. Određivanje ukupnog broja mezofilnih bakterija u ispitivanim uzorcima vršeno je prema metodi ISO 4833. Merenje promene dielektričnih svojstava na koži ribe obavljeno je pomoću aparata torimetar (The Torry Fish Freshness Meter). Rezultati su pokazali da pakovanje sveže pastrmke u modifikovanoj atmosferi (60% CO2 + 40% N2 i 40% CO2 + 60% N2) ima prednosti u pogledu rasta ukupnog broja mezofilnih bakterija i opadanja torimetrijske vrednosti u odnosu na vakuum pakovanje i pakovanje sa većom koncentracijom (90%) ugljen-dioksida

The Intake of Phosphorus and Nitrites through Meat Products: A Health Risk Assessment of Children Aged 1 to 9 Years Old in Serbia

This study provides the data on dietary exposure of Serbian children to nitrites and phosphorus from meat products by combining individual consumption data with available analytical data of meat products. A total of 2603 and 1900 commercially available meat products were categorized into seven groups and analysed for nitrite and phosphorous content. The highest mean levels of nitrite content, expressed as NaNO2, were found in finely minced cooked sausages (40.25 ± 20.37 mg/kg), followed by canned meat (34.95 ± 22.12 mg/kg) and coarsely minced cooked sausages (32.85 ± 23.25 mg/kg). The EDI (estimated daily intake) of nitrites from meat products, calculated from a National Food Consumption Survey in 576 children aged 1–9 years, indicated that the Serbian children population exceeded the nitrite ADI (acceptable daily intake) proposed by EFSA (European Food Safety Authority) in 6.4% of children, with a higher proportion in 1–3-year-old participants. The mean phosphorus concentration varied from 2.71 ± 1.05 g/kg to 6.12 ± 1.33 g/kg in liver sausage and pate and smoked meat products, respectively. The EDI of phosphorus from meat products was far below the ADI proposed by EFSA, indicating that the use of phosphorus additives in Serbian meat products is generally in line with legislation