نشریه بهداشت مواد غذایی
سال دوم شماره 1 (پیاپی 5، بهار 1391)

Ice cream is a popular dairy product especially in warm seasons. Due to its lengthy shelf life, it is considered as one of the potentially high-risk foods in transmission of food-borne pathogens. The aim of this study was to evaluate the bacterial contamination of ice cream in Urmia city. To achieve this goal, Urmia city was divided into four regions based on scattering of the ice cream retailers. Afterwards, 144 samples were purchased from traditional retails using cluster sampling method. Bacterial contamination of the samples was analyzed according to the procedures of the Iranian National Standards. Based on the results, 78% of the samples contained the load of contamination higher than 4.2 × 107 CFU/g. Moreover, 82.9% of the samples were contaminated with more than 10 CFU of Enterobacteriaceae per gram. Results also revealed that 52.2% and 2.8% of the samples were contaminated with E. coli and coagulase positive Staphylococcus aureus, respectively. Salmonella was not detected in any of the samples. High microbial contaminations in traditional ice creams represent non-hygienic practices at different stages of production.

Ochratoxin A (OTA) is a mycotoxin that possess a risk to human health due to its nephrotoxic, immunotoxic, mutagenic, teratogenic and carcinogenic consequences. This study was undertaken to determine the presence and levels of OTA in different types of rice distributed in Isfahan. For this, a total sample of 120 from 8 various types of rice was obtained from retail markets of Isfahan. Using ELISA method the samples were analyzed for the presence and contamination level of OTA. According to the kit manufacturer’s instruction, the recovery percentage of OTA in spiked rice samples at concentration of 5 ng/g was estimated at 84.9% and the detection limits for OTA was 0.625 ng/g. Analytical results showed a frequency of contamination of 20.8% of total rice samples. Levels of OTA in positive samples ranged from 1.07 to 10.83 ng/g and the average contamination level of samples was estimated at 3.5 ng/g. Among the samples, 3.3% were exceeded the permissible limits of 5 ng/g set by the European Regulations for OTA in cereals. According to the results, the daily intake of OTA via contaminated rice was estimated at 5.6 ng/kg bw/day.

Lipid oxidation is one of the most deteriorative reactions occurred in foodstuff which has harmful impacts on the both food quality and consumer's health. This study was designed to speculate the influence of three conventional cooking methods including boiling, frying and grilling on lipid oxidation parameters in cooked lamb meat. Sections of lamb meat from longissimus dorsi muscle, taken from native Lori-Bakhtiary sheep species were cut into uniform pieces and cooked using boiling, frying and roasting methods according to the cooking routine and tradition in Iranian society, in terms of temperature and time. Proximate compositions (moisture, lipid, ash and protein) in the raw and cooked meat were determined using the standard methods of analysis. Moreover, weight loss was measured after each treatment. Lipid oxidation parameters such as peroxide value, conjugated diene and TBARS indices were measured in the raw and cooked samples. Evaluation of lipid oxidation parameters showed that peroxide value was significantly decreased in all cooked samples. In contrast, conjugated diene value was significantly increased in the fried and grilled samples (p<0.05) while, boiling for 90 min was resulted in significant increase in TBARS number (p<0.05). Although compared to the other methods, lower temperature was applied in the boiling process; higher level of lipid oxidation was developed. This might be due to the longer cooking duration in boiling method. Therefore, in the future studies, reduction of boiling duration should be further assessed considering the microbial and nutritional point of views.

Fish is considered as highly perishable food which spoils soon after death if not preserved properly. Consumption of spoiled fish results in the outbreaks of food poisoning such as histamine poisoning. Biogenic amines are the causative agents of histamine poisoning which are produced by various bacterial species. The aim of this study was to determine the amount of histamine and to identify the histamineproducing bacteria on frozen Longtail tuna (Thunnus tonggol) hunted from south of Iran. Microbial examinations and measurement of histamine were performed on the muscles around the gills of twenty five frozen samples. The results indicated that the mean ± SE Log CFU/g for total microbial and psychotrophic counts were 4.81 ± 0.26 and 4.66 ± 0.25, respectively. Different bacterial isolates were identified as histamine-producing bacteria i.e., Clostridium perfringens (24.4%) followed by Proteus spp. (23.0%), Klebsiella spp. (13.9%), and Enterobacter spp. (11.1%). Histamine content in 65.0% of the samples was more than the maximum acceptable level of 50 ppm. Therefore, there is a seafood safety risk in the current harvesting and post harvesting methods used in Longtail tuna industry.

Due to the adverse side effects of synthetic antioxidants, the search for natural and safe antioxidants has become crucial. In this study, the total phenolic compound contents and antioxidants activity of persimmon skin was investigated. The extraction was carried out by means of maceration method using ethanol and methanol solvents with ratio of 1 part persimmon skin to 5 parts of solvents. Afterwards, the total phenolic compounds and antioxidants activity was measured. According to the results, ethanolic and methanolic extracts contained 255.6 and 214.15 mg gallic acid per 100 g of persimmon skin, respectively. Moreover, ethanolic extracts showed a higher activity for scavenging free radicals compared to methanolic extracts.

Enrofloxacin is one of the broad-spectrum antibiotics in veterinary medicine which in recent years its application has grown considerably for the control of infectious diseases in farmed fish. The aim of this study was to quantify enrofloxacin residue in muscle and liver of rainbow trout cultured in Chaharmahalva- Bakhtiary province using ELISA method. For this, the samples were obtained from the farms located in Ardal and Koohrang areas during the spring and summer of 2011. Three farms were chosen from each area and 15 samples were taken from three weight categories including < 50, 50-150 and > 150 g 5 samples from each category). Results revealed that maximum (58.33) and minimum (23.33) percentage of enrofloxacin residue was determined in <50 g and >150 g categories, respectively. In Koohrang region, the quantity of enrofloxacin residues in muscle and liver samples was 13.84 ± 11.50 and 19.95 ± 18.06, respectively. Meanwhile in Ardal, the quantity of the residue was estimated at 12.83 ± 11.62 and 11.22 ± 11.09, respectively. Considering the sampling time, among spring samples the quantity of the residues in muscle and liver was estimated at 14.27 ± 13 and 22.06 ± 21.69, respectively. The quantity of enrofloxacin among the summer samples was 12.40 ± 10.29 and 8.86 ± 7.31, respectively. Moreover, mean value of enrofloxacin residue in the muscle and liver of Koohrang was higher than Ardal region. It was concluded that enrofloxacin residue was lower than the maximum acceptance limit determined by the European Union.

Ever-increasing public debates over the adverse effects that may result from exposure to the chemical preservatives have enhanced the interests for the consuming of preservative-free foods or at least the product containing natural preservatives. In this laboratory experiment, the antimicrobial effect of aqueous extracts of Saffron petals against Salmonella typhimurium, Listeria monocytogenes, Escherichia coli O157:H7, Bacillus cereus and Staphylococcus aureus were investigated using the disk diffusion method. Moreover, the Minimum Inhibitory Concentration (MIC) of the extract was assessed by agar dilution and broth microdilution method. According to the results, S. typhimurium was found as the most sensitive, while, S. aureus and E. coli O157:H7 as the most resistant species. MICs of the extract by microdilution method were estimated at 40 mg/ml for all of the 4 bacterial species. The results also revealed that the extract of Saffron petals could be used as a natural preservative against the aforementioned bacteria.

Thirty-six samples of infant formula with different production dates and various brands were purchased from Isfahan city during 2012. The samples were assayed for the presence and quantity of melamine by ELISA screening method. According to the results, in any infant formula melamine contamination was observed above the detection limit of the kit (10 μg/L). Therefore, it was concluded that the infant formula at Isfahan retail is not considered a health hazard from the melamine contamination point of view.