نشریه بهداشت مواد غذایی
سال سوم شماره 1 (پیاپی 9، بهار 1392)

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 asone of the most popular types of traditional cheeses made from raw sheep milk or sometimes cow milk inWest-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.

Black mouth croaker is considered as a new and valuable resource in the deepwater of the Oman Sea. This study describes the chemical proximate composition, the fatty acid profiles of the fish oil using gas chromatography and phosphorus element (colorimetric method) of the fish muscle. Moreover, the pattern of protein using polyacrylamide gel electrophoresis (SDS-PAGE) was carried out. Proximate composition of the fillet was calculated in wet weight as follow: 79.32±0.299% moisture, 18.19±0.145% protein, 1.01±0.032% fat and 1.434±0.047% ash. The concentration of total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) were measured 39.54±0.272%, 37.66±0.161% and 23.56±0.369%, respectively. Among PUFA, concentration of DHA (9.43±0.345%) was obtained more than EPA (1.16±0.051%) (p<0.05). Phosphorus content was 260.73±0.134 mg/100 wet weight. Based on SDS-PAGE, the 11 protein bands in the range of 10 to 200 kDa were detected. Myosin heavy chain (MHC) showed the most dense band. According to high nutritional value and lean-flesh of black mouth croaker, this species may be appropriate for the production of frozen fillet and surimi.

The aim of this study was to analyze the coA gene on Staphylococcus aureus isolates collected from milks of native buffaloes in north-west of Iran. For this purpose, seventy five S. aureus isolates were examined by PCR-RFLP. Amplification of coA gene revealed various amplicons with a sizes of approximately 600, 700, 760 and 850 bp in 12, 25, 29 and 9 of the isolates, respectively. AluI digestion of the amplicons demonstrated that the isolates had the same PCR band size in the same PCR-RFLP patterns. The result of coA gen analysis was similar to the isolates from cattle milk.

Nisin is a natural preservative produced by strains of Lactococcuslactis subsp. Lactis, has been approved for use in food by the Joint Food and Agricultural Organization/World Health Organization (FAO/WHO) Committee on Food Additives and has been awarded generally recognized assafe (GRAS). It remains the only bacteriocin allowed in food as an addedpreservative. Nisin has a broadspectrum of antimicrobial activity againstgram-positive bacteria, thus one of the problems associated with nisinapplication is inhibition of starter culture and prevention of ripening, which is required for development of cheese characteristics during ripening. In the current study, the effects of different concentrations of nisin and temperature on growth and activity of lactic acid bacteria in model cheeses manufactured fromultrafiltrated milk was evaluated. Cheese samples were supplemented with nisin atconcentrations of 0, 2, 4 and 6 μg/g and stored at 8 and 25 °C up to 60 days. Microbiological and physico chemical properties of the cheese samples were analyzedat 0, 1, 8, 15, 30, 45 and 60 days. Results showed that addition of nisin at concentrations of 4 and 6 μg/g affects (p<0.01) the growth of lactic acid bacteria and so prevents pH reductionduring cheese ripening (p<0.01). Moreover, roomtemperature decreased significantly (p<0.01)nisin activity. According to the results, nisin at concentrations less than 4 μg/g along with refrigeratorstorage temperature could be used as a natural preservative in Cheese manufactured fromultrafiltered milk.

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 highlyimportant 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 thatmost 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.

Streptococcus iniae is an emerging zoonotic pathogen that represents a threat to the aquaculture industry worldwide and poses a risk to humans’ health. The aim this study, was to evaluate the effect of cumin (Cuminum cyminum) essential oil and nisin on the growth of S. iniae. For this purpose, the fillets of rainbow trout (Oncorhynchus mykiss) were inoculated with 103 of S. iniae and afterwards were treated with the different concentrations of cumin essential oil (0, 0.005, 0.135 and 0.405%) as well as nisin (0, 0.25 and 0.75 μg/ml). The samples were stored at 4 and 10 ºC for 15 days. Results revealed that in the samples stored at 4 °C the solo application of each of nisin and cumin essential oil could inhibit the growth of S. iniae until day 9; meanwhile, in combining form the inhibition of bacterial growth was occurred for 3 days. In the samples stored at 10 ºC, nisin and cumin essential oil hindered the bacterial growth for 3 and 6 days, respectively. Moreover, combination of the two materials inhibited the bacterial growth until day 6. The highest synergistic effect was observed in 0.405% of cumin essential oil and 0.75 μg/ml of nisin at 4 ºC. However, at 10 ºC, 0.135 and 0.405% of cumin essential oil together with 0.75 μg/ml of nisin had the highest synergistic effect. As a significant (P<0.05) difference was observed between the treatment and control groups, it could be concluded that cumin essential oil and nisin could efficiently inhibit the growth of S. iniae.

Given that the capacity of vegetables and cucurbits absorption and retention has large amounts of nitrite and nitrate. Therefore, the intake of these products can threaten human health. The aim of this study was to determine nitrite and nitrate in cucurbits and vegetables cultivated in plains of sothern and eastern parts of Kermanshah. For this purpose, a total number of 330 samples was examined for determination of nitrate and nitrite. The samples were analyzed according to the instructions provided by the Institute of Standards and Industrial Research of Iran (No. 4106). The results showed that there are significant differences in the mean value of nitrite in vegetables and cucurbits, in the sampling locations (P<0.01). However, this difference was not significant (P>0.05) in the case of nitrate. The highest level of nitrite was estimated at 6.05±2.1 and 6.12±0.845 mg/kg in radish tubers and the lowest level was estimated at 0.1±0.022 and 0.174±0.085 mg/kg in cucumber samples in Mahidasht and Drood and Framan plains, respectively. In addition, the highest amount of nitrate in the Mahidasht plain was determined in spinach (392.11 ± 21.17 mg/kg) and in the Drood and Framan plain was observed in radish tubers (316.94 ±158.02 mg/kg). The lowest levels of nitrate in the both sampling areas were determined in tomatoes (11.42 ± 3.56 and 9.1±5.2 mg/kg, respectively). Moreover, a significant difference (P<0.01) was observed in the mean quantity of nitrate and nitrite in the different vegetables or cucurbits. It was concluded that the level of nitrite in some vegetables and cucurbits was higher than acceptable limit. Therefore, it is essential to reduce the application of nitrogen fertilizers in these areas.

The aim of this study was to determine Lead and Zinc contamination in the muscle andliver tissues of Cyprinus carpio, Liza auratus and Rutilus frisii kuttom in 2010. Thirty six samples were obtained randomly from Tehran Sarcheshmeh market. According to the results, the mean concentrations of Pb andZn in the liver and muscles samples were 2.19±0.58 143.86±12.61 mg/Kg, respectively. This indicated a significant (P<0.05). Moreover, highest concentration of Pb (6.63±0.15 mg/Kg) and Zn 319.66±3.05 mg/Kg) was found in the liver of Liza auratus. Meanwhile, the lowest concentration of Pb (0.41±0.11 mg/Kg) and Zn (10.80±1.50 mg/Kg) was determined in the muscle of Cyprinus carpio. The determined mean concentration of Pb and Zn in the liver and muscle of Caspian Sea fishes 2.19±0.58 and 143.86±12.61 mg/Kg. Data revealed that the concentrations of Pb and Zn were above the acceptable limit determined by NHMRC, UKMAFF and FDA.