نشریه بهداشت مواد غذایی
سال هفتم شماره 4 (پیاپی 28، زمستان 1396)

In this study, strains of lactic acid bacteria capable of bacteriocin production were isolated from Lighvan cheese samples obtained from East Azerbaijan, Iran. Among 16 isolates initially identified as Lactococcus lactis, four isolates were phenotipically determined as bacteriocinogenic. The isolates showed inhibitory effect on the growth of Gram-positive food borne pathogens including Staphylococcus aureus, Bacillus cereus, Clostridium perfringens and Listeria monocytogenes by the agar spot test. Selected isolates were PCR-positive for nisin-encoding gene. The strains produced antibacterial substances resistant to α-amylase but sensitive to trypsin and proteinase K. Thermo-stability was indicated after treatment at 100 °C for 30 minutes. The antibacterial activity was pH dependent and occurred in pH 3 and 6, but at pH 9 the antibacterial activity was mainly restricted. No loss in antibacterial activity was recorded after treatment with SDS, Tween20, Tween 80, Triton X-100, urea and EDTA. The results suggest the potential application of these isolates as biopreservatives in food products.

The aim of this study was to determine the effects of nisin (250 international units per gram), chitosan (1%), eringo extract (1%), combination of three material and salt treatment (1.5%) on the quality and sensorial traits of rain bow trout (Oncorhynchus mykiss) roe during refrigerated (4±1 ̊C) storage for 60 days. Lipid, ash, moisture, pH, amount of TVN, TBA, Aerobic mesophilic bacteria, psychrotrophic bacteria, yeast and mold were evaluated at 0, 15, 30, 45 and 60 days. Sensorial analyses of samples were evaluated. The results showed that Chitosan and combinational treatment had significant effect (p≤ 0.05) in decrease of microorganisms after 45 days. In addition, TVN had a significant increase during the time (p≤0.05) but in Chitosan and combinational treatment not observed significant change until 45 days. According to the sensory evaluation, was not significant difference between the chitosan and combination treatments until 45 days. Based on the results of chemical and biological analyses, control, salt, nisin and E.extract were unusable between 0 and 15 days. Therefore, it can be concluded that the use of chitosan improved shelf life and organoleptic properties of fish roes effectively.

Bacillus is the dominant genus encloses gram-positive spore-formers that some are considered as a threat to the quality of foods and consumers’ health. This study aimed to explore the occurrence of Bacillus species in raw milk tankers and dairy processing equipments as well as to examine the biofilm-forming ability of the isolates. For this reason, a total of 80 samples consisting of 30 samples obtained from raw milk tankers, 30 samples of dairy processing equipments and 20 samples from various surfaces of the production plant was collected. According to the results, 16.66% of the samples obtained from raw milk tankers, 20% of dairy processing equipments and 40% of surface samples were found positive for Bacillus species. Various species of the Bacillus were found; amongst B. cereus with 36% and B. aloe and B. pumilus with 4% occurrence rate, were the most and least abundant species, respectively. Results of biofilm production revealed that 96% of the isolates were capable of producing biofilm. Eventually, it was concluded that conventional CIP procedure is unable to entirely remove the biofilm of Bacillus species from dairy plant surfaces. Hence, there is a need for a new approach to conquer the problem.

Salmonellosis is an important disease in animals and human which is caused by different serovars of Salmonella ýenterica. Serovars Typhimurium is one of the most prevalent sorvars in humans. Quinolones and floroquinolones ýare the family of extended-spectrum antibiotics which are used in salmonellosis treatment. Qnr genes are the ýplasmid-mediated quinolones resistance which leads to resistance in Enterobacteiacea. The aim of this study is ýidentification of quinolone resistance genes qnr in Salmonella Typhimurium isolated from food samples. In this ýstudy, 60 Salmonella samples isolated from food was collected and confirmed by culture and biochemical tests. ýSerotyping was done by O and H antisera. Multiplex-PCRþ þý was performed to identify qnrA, qnrB and qnrS genes. ýAll of the 60 isolates were confirmed as Salmonella by culture and biochemical tests. The results of serotyping ýshowed all the 60 isolates were belonged to serogroup B and serovar Typhimurium. Multiplex-PCR test showed 5 ýsamples had the qnrB, 4 had the qnrS and 1 harboured qnrA gene. The results of this study shows the presence of ýqnr genes in Salmonella Typhimurium isolated from food samples which has a specific public health importance. ýTherefore, there should be sureveillance and montoring programs to prevent this quinolone resistance.ý

Lactobacilli are known to have an inhibitory effect on the growth of a wide range of food spoilage and foodborne pathogens. The present study was conducted to evaluate the combined effect of Lactobacillus acidophilus Lactobacillus plantarum (5 logs cfu/g) and also the combined effect of Lactobacillus plus EDTA (50 mM) on the shelf life of chicken breast meat. Treatments were grouped into the following: 1. without Lactobacillus and EDTA (C); 2. with Lactobacillus without EDTA (AP); 3. with Lactobacillus and EDTA (APE). Samples were stored at 4 ± 1°C and evaluated periodically for microbial counts (aerobic mesophilic count, coliform count and psychrotrophic count). Microbial analysis indicated that using of Lactobacillus species and Lactobacillus EDTA had significant effects (p

Among environmental contaminants, heavy metals are the most dangerous pollutants. heavy metals are a major environmental impact. The purpose of present study was to identify Lead and Tin heavy metals in refined, unrefined and beeswax honey in Zanjan Province. In this study, 30 samples of honey were randomly collected from the honey supply at retails of Zanjan province. Determination of Lead and Tin concentrations were applied by graphite furnace atomic absorption spectrometry and flame atomic absorption spectrometry, respectively. According to the results, the highest concentrations of lead and tin were found (116 ppb and 221.27 ppm) in beeswax honey. The reason for the high levels of tin in honey wax is storage of honey in tinned cans. Moreover, the reason for the high contamination of lead in honey samples could be environmental contaminants caused by nearby factories in the region. Comparison of the average heavy metals honey by the standards of the WHO also indicates that lead and tin in all types of tested honey were less than the approved limit (220 ppb). Tin concentration in unrefined and refined honey was less than the standard limit; however, in beeswax honey, it was close to the standard (250 ppm). Besides, beeswax and tin had a remarkable effect on the amount of lead. It was concluded, honey at Zanjan province was wholesome based on Lead and Tin contaminants.

The plant based antimicrobial compounds have received great attentions last decades. Among plant, green tea is a very interesting medicinal plant due to its various antioxidant and antimicrobial compounds. Thus the aim of this study was to evaluate the effects of solvent type on antimicrobial activity of gained extract. Three common solvent, namely, ethanol (80%), ethyl acetate and hexane were selected as polar, semi polar and non-polar solvents, respectively. The results indicated that among selected solvents, the ethanol (80%) had the highest extraction efficiency (7%) compared to ethyl acetate (3%) and hexane (2%). The antibacterial analysis was also shown that the obtained extract from ethanol (80%) possess the least minimum inhibitory concentration and minimum bactericidal concentration (250 mg/L) on either selected gram positive Staphylococcus aureus or gram negative E.coli bacteria. Consequently, it shows the highest antibacterial activity compared to other extracts. The ethanol based extract with obtained MIC and MBC concentrations gives antifungal effects as well, with 60% growth inhibition.

Due to an increase of environmental pollutants and their consequences entry in foods, studies on the types of pollution in different food types become of high importance. The present study was carried out to assess Zn, Pb, Cd and Cu contents in wheat and bread of Hamedan City during 2015. For this purpose, 4 wheat farms and 4 bakeries (Lavash, Barbari, Sangak and French bread types) were selected for sampling. After acid-digestion method, the concentrations of the metals were determined using ICP-OES in 3 replications. Statistical analyses were performed using the SPSS statistical package. Results showed that the mean concentrations (mg/kg) of Zn, Pb, Cd, and Cu in the bread samples were 5.47 ± 2.48, 0.06 ± 0.04, 0.92 ± 0.36 and 1.57 ± 0.14, respectively. The mean concentration of these metals (mg/kg) in the wheat samples were 4.93 ± 1.34, 0.17 ± 0.16, 0.92 ± 0.55 and 1.02 ± 0.31, respectively. Also comparing of the mean concentrations of metals with WHO permissible limits it was revealed that the mean concentrations of Zn, Pb, and Cu were lower than permissible limits, meanwhile concentrations of Cd was higher than permissible limits. It seems that excessive using of agricultural inputs and application of sewage sludge and wastewater for irrigation could be the main reason for the high concentrations of heavy metals in agricultural products and could have public health consequences.