Histamine determination in Koopeh cheese in West-Azerbaijan province by HPLC

Histamine as a primary heterocyclic amine has an important role in human physiology particularly in nervous system as a chemical mediator and neurotransmitter that was found in many foods such as cheese, milk, meat, fish, beer, wine and vegetables. Increasing of histamine concentration in foods is often related to low quality of raw materials, contamination, improper food processing or storage. Therefore, the amount of histamine content is used as a good indicator of hygienic quality in foods and the degree of freshness or spoilage of foods. Histamine can cause symptoms in sensitive consumers such as: redness of face, sweating, palpitations, headache, oral burning and bright red rashes. Cheese provides an ideal environment for the production of proteolytic releases of free amino acids and biogenic amines such as histamine. The aim of this study was to evaluate the amount of histamine in Koopeh cheese as one of the most popular types of traditional cheeses made from raw sheep milk or sometimes cow milk in West-Azerbaijan province, Iran. Experiments conducted by HPLC method on 70 samples of traditional Koopeh cheese revealed that the least amount of histamine was 2.43 ppm and the highest value was estimated at 1102.24 ppm. The average amount of histamine in cheese samples was 304.23 ± 150.89 ppm. Histamine production in cheese and other foods is based on the presence and growth of decarboxylase-positive microorganisms. Therefore, providing guidelines that reduce the population of these types of microorganisms will be effective on decreasing the amount of biogenic amines and histamine in particular

Antibacterial combined effects of nisin and onion essential oil under different concentration of NaCl and pH against Listeria monocytogenes in vitro

In the present study, the anti-listeria activity of onion (Allium cepa L.) essential oil (EO), nisin as well as their combination at various pH values (4.8, 5.8 and 6.8) and different NaCl concentrations (0, 0.5, 2.5 and 4.5%) was investigated against Listeria monocytogenes by microtiter plates at 30°C. Minimum inhibitory concentrations (MICs) were assessed for the nisin, onion EO as well as their combination. Subsequently, fractional inhibitory concentration (FIC) was evaluated under different pH and NaCl concentrations. Both nisin and EQ showed significant antimicrobial effects against L.monocytogenes. Moreover, the nisin and onion EO exhibited MICs of 12.5 IU mL-1 and 125 μg mL-1, respectively. FICs of the nisin and onion EO alone and in combined form, along with various combinations of pH and NaCl concentration, showed clearly anti-listeria effect as synergistic, additional or indifference. Regardless of NaCl concentrations, the anti-listeria activity of both agents was strongly influenced by pH. Moreover, regardless of pH value, the growth of the bacterium was also affected by increasing of NaCl concentrations. It was concluded that, pH value of 4.8 and NaCl concentration of 4.5% had significant anti-listeria effect. In addition, it was found that, the effect of NaCl concentrations for each of the combination forms of treatments at various pH was different.Therefore, there are necessity to design and apply a comprehensive predictive model

Validation of histamine determination Method in yoghurt using High Performance Liquid Chromatography

Biogenic amines are organic, basic nitrogenous compounds of low molecular weight that are mainly generated by the enzymatic decarboxylation of amino acids by microorganisms. Dairy products are among the foods with the highest amine content. A wide variety of methods and procedures for determination of histamine and biogenic amines have been established. Amongst, HPLC method is considered as reference method. The aim of this study was to validate Reversed Phase HPLC method determination of histamine in yoghurt. The mobile phase consisted of acetonitrile/water (18:88 v/v) and the flow rate was set at 0.5 ml/min using isocratic HPLC. Detection was carried out at 254 nm using UV-detector. Calibration curve that was constructed using peak area of standards was linear and value of correlation coefficient (r2) was estimated at 0.998. Good recoveries were observed for histamine under investigation at all spiking levels and average of recoveries was 84%. The RSD% value from repeatability test was found to be %4.4. Limit of detection and limit of quantitation were 0.14 and 0.42 µ/ml, respectively. The results of validation tests showed that the method is reliable and rapid for quantification of histamine in yoghurt

Study on the overview on food borne bacteria in food with animal origin in Iran; Part three: seafood

The current retrospective study was focused on the contamination of seafood in Iran during the years 1999 to 2012. The isolates were Clostridium botulinum, Clostridium perferingense, Escherichia coli, Listeria monocytogenes, Salmonella, Shigella, Staphylococcus aureus and Vibrio parahemolyticus. C. botulinum type E was the most prevalent type of bacteria in the fisheries products, responsible for the most cases of botulinal food poisoning. The presence of coliforms and E. coli in the seafood was due to environmental pollution. Additionally, in the processed food, the contamination of potable water and poor handling of the products are the main sources. L. monocytogenes was isolated from fresh, frozen and processed food. The microorganism is able to grow in the refrigeration condition and multiply in the processed food. The temperature of cold smoking (20-30 ºC) cannot stop growing of Listeria. High prevalence of Salmonella in water and fisheries product was mainly because of the low environmental sanitation and various geographical conditions. However, Compost fertilizer and flowing of the swages through the farms were considered as the major source of contamination. S. aureus is not a typical microorganism of the fisheries farms but may contaminate them during the processing or in-appropriate handling of the products. V. Parahemolyticus is a normal habitant organism of the pelagic area. The organism usually find in the warm water and presents in the tropical conditions. Different species of Vibrio may contaminate the salty water in the warm seasons and so contaminate the aquatics farms in these areas. In general, the prevalence of vibriosis was associated with the consumption of semi-cooked food stuff and/or the secondary contamination of the processed ones

Study on the overview on foodborne bacteria in food with animal origin in Iran; Part four: Poultry and egg

In this study, the contamination of poultry meat and eggs to pathogenic bacteria was investigated in Iran, for over three decades. Health assessment of these two products is highly important due to their high level of consumption and consequent health risks of food borne diseases such as salmonellosis. Many reports indicate the presence of majority of pathogenic bacteria such as campylobacter, staphylococci, salmonellas, etc. in the poultry abattoirs across the country. It seems that most of these contaminations had been occurred through cross contamination during slaughtering or other stages of processing. Although many bacterial contaminations have been reported in eggs (e.g., streptococci, staphylococci, or Escherichia coli), most of studies have focused on salmonella as eggs are among the major transmission routes of this bacterium. In several suveys, salmonella has been isolated from the shell of the eggs of native breeds. According to the studies, campylobacter contamination has not been reported. Moreober, occurrence rate with other bacteria species was very low. It seems that due to the high proportions of chicken meat and eggs in the food basket of community, even low levels of contamination could be of great concern. It was concluded that maintaining of hygienic conditions and improving the knowledge of producers in the food production chain could be effective in reducing the overall contamination of pathogenic bacterial

Study on the overview on food borne bacteria in foodstuffs with animal origin in Iran; Part two: meat and meat products

The present study was aimed to review the contamination of meat and meat products with pathogenic bacteria in Iran. Little information is available about the contamination of meat and meat products with Bacillus cereus, because of the low contamination rate with the microorganism. The situation is about the same with Brucella, as the microorganism can hardly be seen in the muscles. However, not too many information is available on the contamination with Campylobacter jejuni, even though, the contamination of chicken meat with the campylobacter was addressed. Clostridium butolinum was the main discriminated bacterium to contaminate fish and its products and canned meats. Studies revealed that the big portions of meat were less likely contaminated with E. coli compared to the minced meat. Our study showed that the cross contamination of sausage is often occurred after the production chain. The situation was possibly attributed to the improvement of hygienic conditions of slaughter-houses and meat industries. Limited information was found on the contamination with Listeria monocytogenes and available data indicate that the microorganism can be present in meat and meat products. The most important factor for prevention of contamination is restricted inspection of slaughtered animals before slaughter and omission of diseased animals. Much information was accessible on the cross contamination with Salmonella in Iran and elsewhere. Salmonellosis is not common in the slaughtered animals despite its epidemiological and public health issues. The problem was also associated with the restricted inspection. Study about the staphylococcal contamination of meat was proportionately numerous. The contamination was mostly occurred in the minced Kebab in the warm seasons of the year. Generally, a low percentage of such contaminations were found in the meat products and sausage, in the surveys

Study on the overview on foodborne bacteria in foodstuffs with animal origin in Iran; Part one: milk and dairy products

In this study contamination of milk and dairy products with pathogenic bacteria in Iran has been reviewed. There are many surveys in some cases, while there is no information about some pathogenic bacteria in milk or very few data is available. It should be point out that the results come from the cross sectional surveys are needed for further epidemiological and experimental studies. In general the contamination of milk and dairy products has decreased in the course of time as the production methods and producer’s knowledge increased. On the other hand application of new and precise methods of detection and investigation of bacteria lead to excess detection of pathogenic microorganisms in milk. Therefore regular continuation of cross sectional studies along with using   precise and sensitive methods of sampling and analysis of bacteria are necessitated. Besides making available of needed data about the contamination of milk and milk products with pathogenic bacteria, this information make enable to adopt the effective preventive precautions for elimination or reduction of contamination

The effect of monolaurin in combination with Mentha pulegium L. and Mentha spicata L. essential oils on Bacillus cereus and E. coli O157:H7: in vitro study

Monolaurin, pennyroyal (Mentha pulegium L., Labiatae) and spearmint (Mentha spicata L.) essential oils have various antibacterial activities on microorganisms. Enhancement of antibacterial activity and detection of their combined effects on B.cereus ATCC 11778 and E. coli O157:H7 were the purpose of this investigation. Monolaurin preparation, spearmint and pennyroyal essential oils preparation and analysis of their chemical composition with GC-MS method, bacterial inoculums preparation, antimicrobial susceptibility testing using broth micro dilution MIC testing and finally statistic analysis of results with SPSS software package were the material and methods used in this research. MIC (minimum inhibitory concentration) of pennyroyal oil, spearmint oil, monolaurin, monolaurin-pennyroyal oil combination and monolaurin-spearmint oil combination on B.cereus and E. coli O157:H7 were significant (