نشریه بهداشت مواد غذایی
سال دوم شماره 4 (پیاپی 8، زمستان 1391)

Mycobacterium avium subsp. paratuberculosis (Mycobacterium paratuberculosis) is considered as a potential significant public health threat due to its possible association with Crohn’s disease in humans. This is a study aimed to investigate the effect of different salt concentrations on survival of Mycobacterium paratuberculosis during ripening and storage of Iranian ultra-filtrate-white cheese (IUFWC). For this purpose, retentate was inoculated with 2 Log cfu/g of Mycobacterium paratuberculosis. Afterwards, model cheeses were prepared with 2%, 3% and 4% of salt. Quantity of Mycobacterium paratuberculosis was estimated throughout the ripening and storage of IUFWC using F57-quantitative real time PCR (F57-qPCR) and culture assay. Along with, the populations of lactic acid bacteria as well as physicochemical properties of cheese samples were determined. According to the results, at the early stage of storage period (1 to 30 days) the number of Mycobacterium paratuberculosis was almost constant; however, it was decreased significantly (p<0.01) during the late storage period (30 to 60 days). Data also suggested that Mycobacterium paratuberculosis could persist for a longer (p<0.01) period of time in the samples made with lower (2% and 3%) salt concentration. Consequently, higher salt concentration could shorten the survival of Mycobacterium paratuberculosis in IUFWC. In addition, considering the effect of time on the persistence of Mycobacterium paratuberculosis, storage of IUFWC until the end of storage period (60 days) could inactivate more of the bacterium.

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.

Environmental and food contamination with toxic element arsenic is one of the important issues that are threatening public health and other creatures. In this study, a total sample of 983 consisting agricultural and animal products as well as water samples was analyzed for arsenic contamination. According to the results, the highest concentration of arsenic (1.737 mg/l) was found in the piped water of Aliabad. Moreover, the highest level of arsenic contamination was detected in wheat obtained from Giklo and Gondak (0.14 mg/kg). Accordingly, highest arsenic level in barley, peas and lentils, was estimated in the samples of Gondak (0.11 mg/kg), Giklo (mg/kg 0.013) and Ghojagh 0.017 mg/kg), respectively. In addition, the highest mean concentration of arsenic in meat and milk samples was found in Ghojagh (0.167 mg/kg) and Gondak (0.0129 mg/l). The results revealed that the contamination level of arsenic in all crops, meat and milk samples were lower than the maximum acceptable limit adopted in many other countries. However, the concentration of arsenic in water samples was 174 times higher than the acceptable limit (0.01 mg/l) determined by the Iranian National Standard. Therefore, it is necessary to perform comprehensive studies on contaminations of water sources in this area.

One of the biggest obstacles towards orange juice trade is its limited shelf-life. Microbial spoilage is among the reasons for declining the quality of orange juice during storage. The purpose of this study was to determine the impact of chitosan as a natural preservative to increase the shelf-life of orange juice. For this, different concentrations of chitosan including 0, 0.4, 0.8, 1, 1.2, 1.6 and 2 g/L were used. During the storage periodmicrobial (total bacterial count) and chemical(Brix and pH) characteristics were assessed.Resultsshowed that higher concentrations of chitosan significantly (p<0.05) inhibit the proliferation microbial population throughout the storage period. Moreover, application of higher concentrations (1.6, 2 g/L) of chitosan increased the pH and Brix in orange juice. That is to say, minimum Brix (12.03) and maximum pH value (4.51) was found in the samples containing 2 g/L of chitosan. Microbial (total bacterial count) counts showed the highest value of 3.45 log cfu/ml in the control sample, and the lowest quantity of 2.43 was determined at concentrations of 1.6 and 2 g/Lof chitosan. It was concluded that chitosan can be used as a natural preservative to prolong the shelf-life of orange juice. Consequently,it could be use as an alternative for thermal treatments which haveharmful effects on the nutritional properties of orange juice. However, comprehensive evaluations dealing with the effect of chitosan on various microbial groups should be performed.

Accumulation of heavy metals in fish body causes the destruction of soft tissues and suppression of immune system. Moreover, consumption of contaminated fish causes several consequences in humans. This survey was conducted to determine the concentration of lead, mercury and cadmium in muscle tissue, gill as well as liver of Barbus grypus and Liza abu. These two species are native fishes of Karoon River in Ahvaz area. A total number of 80 sample was obtained during the winter of 201. After preparation and chemical digestion of fish samples, the amounts of heavy metals were determined by spectrophotometer method. According to the results, the overall lead concentration in different organs of the two species was more than mercury and cadmium concentrations. Furthermore, the accumulation of heavy elements in gills was estimated higher than the other organs. Although a significant difference (P<0.05) was observed in heavy metal concentrations between gills and liver samples in Barbus grypus, such difference in the case of Liza abu was not significant. It was concluded that the overall contamination level of heavy elements in Barbus grypus was significantly (P≤0.05) higher than Liza abu.

The use of hydrocolloid coatings is a suitable method to reduce oil uptake in fried foods. In this research, the effects of xanthan and guar gum coatings on reduction of oil uptake as well as sensory and physical properties of fried hamburgers were investigated. Hamburgers were coated with 0.5%, 1% and 1.5% of xanthan as well as 0.3%, 0.5% and 1% of guar. The effect of coatings on redguction of oil uptake, water retention, texture, color change, sensory acceptability of the hamburger samples was assessed. The results showed that the xanthan and guar coatings are the major factors affecting water retention, reduction of oil uptake, texture and color of the fried hamburgers. Coatings resulted in the reduction of oil uptake up to 25%. Data also did not suggest significant differences in sensory characteristics of coated and uncoated samples. The application of hydrocolloid coatings reduced oil uptake, whilst it did not affect the sensory characteristics of fried hamburgers. It was concluded that xanthan and guar gum coatings can improve the organoleptic and nutritional properties of fried food hamburgers.

Ochratoxins are considered as the significant mycotoxins found in animal feeds. Amongst, Ochratoxin A has high pathological consequences on the humans and animals. The aim of present study was to determine the amount of Ochratoxin A in rainbow trout feed produced in Chaharmahal Va Bakhtiary province. For this, four major producers of trout feed were chosen and four different sizes of feed together with one wheat flour sample were obtained from each factory. The samples were transferred to Food Analysis Lab of Shahre-Kord Islamic Azad University. The samples were obtained in three replicates and a total of 60 samples were analyzed for the presence of Ochratoxin A. The analysis was performed by ELISA assay. Results revealed that the quantity of Ochratoxin A in all feed samples were lower than determined contamination level established by Iranian National Standard and EU commission (5μg/kg). However, the contamination levels in all wheat flour samples were higher than defined standard. The amount of Ochratoxin A in samples obtained from various producers was not statistically significant (p<0.05). It was concluded that the overall quality of trout feed produced in Chaharmahal Va Bakhtiary province were satisfactory.

Heavy metal pollution is among the major problems of environmental and food safety concerns. This study investigated the concentration of heavy metals i. e., arsenic (As), cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu) in mushroom crops produced in Kurdistan greenhouses. For this purpose, compost, mushroom crop and soil of four greenhouses with five repetitions for each sample were obtained. A total number of 60 sample was analyzed. The samples were digested using acid digestion method and the concentrations of the metals were determined by atomic emission technique. According to the results, average As concentrations in mushroom was estimated at 89.742 mg/kg, Cd 0.32 mg/kg, Cu 48.868 mg/kg, Pb 3.152 mg/kg and Zn 24.072 mg/kg. The findings showed that the mean concentrations of As, Pb and Cu in all mushroom samples were higher than WHO standards (0.5, 2 and 40 mg/kg for As, Cu and Pb, respectively). However, the concentrations of Zn and Cd in the mushroom samples were in the acceptable limit. Data showed that except for As, the concentrations of all elements in soil and compost samples were lower than the EPA standard. It was concluded that excessive application of chemical fertilizers had resulted in the increasing of heavy metal concentrations in the soil, compost and mushroom crops produced in Kurdistan greenhouses.