ABSTRACT
The presence of aflatoxin M1 [AFM1] and antibiotic residues in milk and milk products is a public health concern. Milk and milk powder have the potential for introducing AFM1 and antibiotic into human diet. In recent years, milk powder has been used on a large scale in dairy factories. Consequently, antibiotic residues and aflatoxin contamination control in these products has gained importance. The aim of this survey was to determine the level of beta-lactam and tetracycline antibiotic residues and also AFM1 contamination of milk powder used in Tehran dairy factories. During 12 months [September 2011 to September 2012], 240 samples of milk powder were collected from ten Tehran dairy factories. All samples were analyzed for the presence of AFM1 using ELISA technique. In addition, antibiotic residues were determined by BetaStar Combo test, a rapid assay for both beta-lactam and tetracycline antibiotics. The samples depicted positive results i.e. 30% and 17.5% for beta-lactam and tetracycline antibiotics, respectively. Also, AFM1 was found in 155 cases [64.6%] with an average concentration of 29.85 +/- 18.99 ng/ L. The results showed the milk powder used by dairy factories is safe in respect of AFM1 contamination and antibiotic residues in Tehran
ABSTRACT
In spite of done improvements in slaughter hygiene and food production techniques, food safety is an important public health issue. Furthermore, the World Health Organization has recently called for a worldwide reduction in the consumption of salt in order to reduce the incidence of cardio-vascular disease. If the level of salt in processed foods is reduced, it is possible that other additives will be needed to maintain the safety of foods. Essential oils are probably one of the natural additives that can use as antibacterial additives. The aim of this study was evaluation of the effect of Zataria multiflora Boiss. essential oil on the growth of Salmonella typhimurium in commercial barley soup. At first, essential oil of Zataria multiflora Boiss. analyzed using GC/MS and the chemical components were identified. Antibacterial activity of Zataria multiflora Boiss. essential oil on the growth of Salmonella typhimurium in commercial barley soup evaluated by using different essential oil concentrations [0.0, 0.005, 0.015 and 0.03%] and two different temperatures [8 and 25°C] during 21 days. Antibacterial activity of Zataria multiflora Boiss. essential oil on the growth of Salmonella typhimurium was statistically significant [p<0.00]. The correlation coefficient of essential oil with log10 of the number of Salmonella typhimurium was -0.402. Zataria multiflora Boiss essential oil probably can used as a proper preservative against some food borne pathogen bacteria in certain foods
Subject(s)
Oils, Volatile , Anti-Bacterial Agents , Hordeum , Food PreservativesABSTRACT
The behaviour of Escherichia coli O157:H7 was studied during the manufacture and storage of Iranian white cheese in brine. Cheese was manufactured using pasteurized cow milk and inoculated with E. coli O157:H7 with inoculum level of 10[3] cfu/ml. Four treatments were designed. Cheeses were made with or without starter culture and kept immersed in 6 or 8% salt brine during ripening and storage. Cheese samples were analysed for E. coli O157:H7 during manufacture and storage period. During cheese manufacture the number of E. coli O157:H7 increased by 10[6] cfu/g, but during ripening and cheese storage the number of organism decreased significantly in the cheese samples made with starter culture [P<0.05]. The results showed an inhibitory effect of starter culture on E. coli O157:H7, but the organism can survive in this kind of cheese for up to 60 days of storage, respecting using starter culture, salt brine concentration and cheese storage time
ABSTRACT
Thyme [Zataria multiflora Boiss] is one of the Iranian traditional spice and it has antimicrobial effect on the pathogenic bacteria which are agents for some current food borne intoxications. Evaluation of antimicrobial effect of mentioned plant essential oil on Staphylococcus aureus in Feta cheese. The essential oil of this plant was obtained by hydrodistillation and analyzed by GC/MS. Effects of different concentrations of this essential oil on Staphylococcus aureus were determined by evaluation of the microorganism growth on the selective media in laboratory, and these effect on the growth of Staphylococcus aureus and when the mentioned concentrations of the essential oil were used in combination with cheese starter culture, the counts of the pathogen were decreased significantly below its toxic dose in this kind of food product. The antimicrobial effect of Zataria multiflora Boiss. in 300 ppm was higher than its lesser concentrations and with concern to the control groups, the synergistic effect between the starter and the essential oil is necessary to achieve this inhibitory effect
Subject(s)
Staphylococcus aureus , Anti-Bacterial Agents , Cheese/microbiologyABSTRACT
About 30% of people in developed countries at least once a year experience a food borne disease. Therefore, there is a need for new methods to prevent the growth of food borne pathogens or decrease the number of them in foods. One of the methods is to use plant essential oils as antimicrobial additives in foods. To establish the usefulness of plant essential oils, they must be evaluated alone or in combination with other preservation factors [such as temperature, storage time and ...] first in the laboratory models and then in food model systems. The aim of this study was to determine of the effect of Zataria multiflora Boiss. essential oil on the growth of Staphylococcus aureus in commercial barley soup using different essential oil concentrations [0.0, 0.005, 0.015 and 0.03%] and temperatures [8 and 25°C] during 21 days. The effect of different concentrations of essential oil on growth rate of Staphylococcus aureus was statistically [ANOVA] significant [p<0.01]. The correlation coefficient of Zataria multiflora Boiss. essential oil with log l0 of the number of Staphylococcus aureus was -0.588. The effect of storage time on growth rate of the organism was also statistically [ANOVA] significant [p<0.05]. The correlation coefficient of storage time with log l0 of the number of microorganism used in this study was -0.2 which showed a decrease in the growth rate of the organism when the storage time was increased. In addition the correlation coefficient of storage temperature with log l0 of the number of Staphylococcus aureus was 0.449. In other words, by decreasing the storage temperature [from 25 to 8°C], the decreasing of the growth rate of the microorganism was observed. The effect of different storage temperatures and their interaction with different concentrations of essential oil on growth rate of Staphylococcus aureus was also statistically [ANOVA] significant [p<0.01]. The results suggested that the Zataria multiflora Boiss essential oil can be considered as a natural preservative in some foods
Subject(s)
Plant Oils , Food Preservation , Staphylococcus aureus , Anti-Infective Agents , Preservation, Biological , TerpenesABSTRACT
During the years 1982-1987 a study was carried out about the rate of the incidence of foodborn infections and intoxications in Tehran which in many cases the consumption of traditional ice cream was the responsible foodstuff. The high incidence of foodborn infections and intoxication in this study was the motivation for a survey on the contamination of traditional Iranian ice cream with important bacteria associated with foodborn infections and intoxications. During the years of 1992-1994, within present study, a total of 390 samples of ice cream were obtained from five different areas in the city of Tehran and analyzed for the detection and enumeration of common and important pathogenic foodborn bacteria. From 150 samples, 122 [81.30%] showed Enterobacteriacae count more than 10[2] per gram of ice cream. In 106 [70.6%] and 2 [1.3%] of samples atypical E.coli and typical E.coli observed respectively. Fifty six samples out of 280 [20%] samples contained more than 10/ g of staphylococcus aureus. From 260 samples, 28 [10.75%] showed Bacillus cereus count more than 10/g and one sample out of 141 samples was shigella positive. No salmonella, Listeria monocytogenes and campylobacter jejuni was isolated from the samples. The survey on the incidence of food infections and intoxications during the study [1992-1994] showed a close correlation between the prevalence of etiological agents and the cases of foodborn infections and intoxications reported from public health agency of the country