نشریه بهداشت مواد غذایی
سال ششم شماره 4 (پیاپی 24، زمستان 1395)

This study aimed to investigate the prevalence of Staphylococcus aureus in raw milk and traditional dairy products of West-Azerbaijan Province and also to evaluate the presence of TSST-1 virulence gene, antibiotic resistance and biofilm formation of the isolates. Using stratified random method, a total of 80 raw milk and traditional dairy products (including traditional cheese, cream and curd) together with 20 nasal swab samples of the dairy products’ manufacturers were collected. S. aureus strains were isolated and identified by conventional culture methods. Afterwards, the isolates were subjected to PCR analysis to detect the presence of TSST-1 gene. According to the findings, 35% of the samples were contaminated by S. aureus. Moreover TSST-1 gene was recognized in 1 cheese and 2 swab samples. Antibiotic resistance profile revealed that most of S. aureus isolates were resistant towards vancomycin, penicillin, and methicillin and sensitive towards co-trimoxazole, gentamicin, rifampin, oxacillin, and cephalothin. Moreover, 2.85%, 17.15%, and 80% of the isolates were capable to form high, moderate and low amounts of biofilm. High occurrence of S. aureus in milk and dairy products which harbor TSST-1 virulence gene, and the strains that demonstrated resistant to several antibiotics and capable of biofilm formation, could be considered a health threat to the consumers of these products.

Sourdough applications in bread production are rising in recent decades continuously due to consumer's desire for natural products containing less chemical preservatives. In sourdough, lactic acid bacteria play a key role in the fermentation process. In this study Lactobacillus plantarum and Lactobacillus sanfranciscensis as single starter and their mixture as a mixed starter were used in the preparation of sourdough. The results showed that the use of single starters increased diacetyl and hydrogen peroxide of sourdough and sourdough fermented with mixed starter had the highest content of diacetyl and hydrogen peroxide. In the end sourdough fermentation period the highest lactic acid bacteria count was associated with sourdough containing L. sanfranciscensis. Effects of different starters were significant on the pH of TTA of sourdough, dough and bread, and also resulted in decreased pH and increased of TTA compared to control bread. The results of the assessment of physicochemical and organoleptic properties of bread showed that sourdough containing mixed starter resulted in increasing of height, specific volume and porosity; however, it reduced the hardness of bread crust and crumb, and retarded the emergence of mold colonies. Sourdough bread containing mixed starter gained the highest score of organoleptic properties. Therefore the use of mixed starters consisting of L. plantarum and L. sanfranciscensis could be considered as a suitable starter culture for the production of sourdough and high quality bread.

This study aimed to investigate the effects of salting of rainbow trout (Onchorhynchus mykiss) roe by pure and mixed salts (3.5, 4.5 and 5.5 %) on the quality and shelf life of the product, with respect to the contents of Total Volatile base nitrogen (TVBN), lipid oxidation (TBA), and on the proximate compositions during storage. The processing of roe leaded to changes in its chemical composition. In comparison with fresh roe, salted roe presented higher contents of TBA and lower content of TVBN. The greatest increases of TVBN were observed in the samples salted by salt without additives, in which TVBN was detected at 43.43 mg/100 g. pH value, salt absorption and TVBN and lipid oxidation had significant increase during storage (p

The use of medicinal herbs plays a vital role in improving the health of human society. Since the plants are the most important transmission route of heavy metals into human food chain and biological cycles, this study was conducted to assess the health risk of concentration of As and Zn in Shirazi thyme, sweet viola, pennyroyal and jujube marketed in Hamedan City during 2015. After preparation of 3 samples of each medicinal plant, the samples were digested in acid according to the standard methods. The concentration of each element in the samples was determined using atomic absorption spectroscopy (AAS) in 3 replicates. Statistical analyses were performed using SPSS statistical package. The results showed that the maximum mean concentrations of As and Zn were 0.035±0.026 and 1880±520 µg/kg related to thyme and viola, respectively. The results of health index for all samples were found lower than one. Moreover, the mean concentration of As and Zn in all samples were lower than WHO permissible limits. Although controlled consumption of medicinal plants has not adverse effect on the consumers’ health, concerning to the bioaccumulation of heavy metals in the long-term, regular periodic monitoring of chemical pollutants content especially heavy metals in medicinal plants are recommended for food safety.

According to consumer's desire to consume foods without preservatives or containing a natural preservative, the use of plant extracts as a food preservative instead of chemicals has increased. This study was conducted to determine the antibacterial effect of different concentration of alcoholic extract of garlic (Allium sativum) on standard strains of Salmonella enteritidis, Bacillus subtilis, Listeria monocytogenes and Yersinia entrocolitica. For this purpose, the agar well diffusion method was used. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were measured with microtiter plate method using the rezazurin reagent. The results showed that garlic alcoholic extract had an inhibitory effect on any four tested bacteria. The highest inhibitory effect was observed on B. subtilis;meanwhile,the slightest effect was found on S. enteritidis. The minimum inhibitory concentration of 0.39 mg/ml was observed for B. subtilis, however the highest amount was estimated at 12.5 mg/ml for S. enteritidis. According to the results of recent research it was concluded that alcoholic extract of garlic had appropriate antibacterial impact against bacteria and therefore could be used as a natural preservative in various foods.

Today, assessing the presence of preservatives in food are important measures to ensure food safety. Potassium sorbate is one of the most usual preservatives that acceptable in some of food for suppressing mold spoilage. In this research sorbate was measured in several industrial fruit juices to make a comparison between spectrophotometry and HPLC assays and consequently to examine the reliability of spectrophotometry data. Although the methods were optimized by maximum speed, attention, reduction of solvent consumption. A total of 28 samples of industrial fruit juices was collected and analyzed. The results showed that all of the fruit juices contained potassium sorbate. Highest level of sorbate was determined in pomegranate juice which was estimated at 7.22, 1.23 ppm by spectrophotometer and HPLC, respectively. The high level of sorbate in spectrophotometry method is related to interference of some material due to their absorbance ability of UV-visible ray. The comparison of spectrophotometry and HPLC data showed that in spite of simplicity and low cost of spectrophotometry, it did not have efficiency to determine the exact amount of sorbate. Moreover, due to the presence of sorbate in industrial fruit juices, it is necessary to strictly monitor sorbate concentration in foods.

Heavy metal pollution in marine environments and the potential for bioaccumulation of contaminants have been considered as a serious threat for a long time. These contaminants accumulate in fish body and then transferred through the food chain to humans. The aim of this study was to determine the heavy metals cadmium, lead, arsenic, mercury and copper and iron metals in muscle and fish oil (Rutilus frisii kutum ،Clupeonella cultriventris ،Liza saliens). Three samples of Rutilus frisii kutum ،Clupeonella cultriventris and Liza saliens were caught in Mahmoud Abad area. One part of the muscle was dried by freeze drying method and another part was used to extract the oil. Then, using the atomic absorption spectrometric and Mercury Analyzer heavy metals concentrations were determined in muscle and fish oil. The results of muscle showed the highest accumulation of mercury (0.347±0.018), cadmium (0.08±0.001), copper (1.2156±0.059) and iron (2.643±0.231) in Rutilus frisii kutum and the highest level of lead (0.3593±0.015) and arsenic (0.0892±0.001) in Liza saliens. Moreover, in the fish oils samples, lead and mercury had the highest concentrations. The heavy metals in the samples were lower than or close to international standards. Therefore, their use does not pose a health problem for the consumers.

Due to similarities with breast-feeding, baby food is used as a partial replacement for babies between 6 to 12 months of age. In this study, five samples of famous infant food supplement consisting of three types from Ghoncheh company (rice with milk, wheat with milk, almond porridge) and two types from Nestle company (wheat and milk, and banana and wheat with milk) were prepared. Samples were digested with nitric acid and the concentrations of cadmium, lead, manganese, molybdenum and nickel were analyzed. In addition, the estimated daily intake (EDI) index for all samples was calculated and compared with tolerable daily intake (TDI) index. The minimum and maximum concentration of cadmium was found in the sample with rice + milk formula (40.3 µg/kg) and infant food supplements containing wheat + milk (58.0 µgr/kg), respectively. The amount of cadmium, lead, manganese, molybdenum and nickel were estimated in the range of 40.3-58.0 ppb, 31.85 ppb, 2.3-4.9 ppm, 417.9-518.8 ppb and 4479.1-6415.0 ppb, respectively. In was concluded that the amount of toxic elements in infant foods marketed in Iran were found below the maximum limit.