Microbiology
Mojtaba Raeisi; Hossein Tajik; Seyed Mehdi Razavi Rohani; Bektas Tepe; Hossein Kiani; Rahem Khoshbakht; Hesamaddin Shirzad Aski; Hamed Tadrisi
Volume 7, Issue 1 , March 2016, , Pages 7-11
Abstract
Listeria monocytogenes is one of the major causes of infections in developing countries. In this study, chemical composition and anti-listerial effect of the essential oil of Zataria multiflora Boiss. alone and in combination with monolaurin were evaluated at different pH values (5, 6, and 7) and temperatures ...
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Listeria monocytogenes is one of the major causes of infections in developing countries. In this study, chemical composition and anti-listerial effect of the essential oil of Zataria multiflora Boiss. alone and in combination with monolaurin were evaluated at different pH values (5, 6, and 7) and temperatures (5 ˚C and 30 ˚C). Chemical composition of Zataria multiflora Boiss. essential oil was evaluated by gas chromatography-mass spectrometry (GC-MS) analysis. Minimum inhibitory concentration (MIC) of the essential oil and monolaurin were determined using microbroth dilution method and the interactions of essential oil and monolaurinwere determined by the evaluation of fractional inhibitory concentrations (FIC) index.Carvacrol (63.20%) and thymol (15.10%) were found as the main components of the essential oil. The MIC values of the oil and monolaurin at pH 7 and 30 ˚C were measured as 312.50 µg mL-1 and 125.00 µg mL-1, respectively. Combination of monolaurin and Z. multiflora essential oil were found to act synergistically (FIC index < 0.5) against L. monocytogenes under different pH and temperature conditions. Decrease in the pH and temperature values have increased the anti-listerial activity of monolaurin and the essential oil. The lowest MIC value of monolaurin and essential oil was observed at pH 5 and 5 ˚C. According to our results, the oil alone or in combination with monolaurin at low pH and temperature conditions showed a promising inhibitory effect on L. monocytogenes.
Food Hygiene
Ladan Mansouri-Najand; Mehrnoush Kianpour; Masoud Sami; Maziar Jajarmi
Volume 6, Issue 3 , September 2015, , Pages 223-226
Abstract
Listeria monocytogenes as one of the most important pathogen in public health concerns is transmitted through consumption of contaminated food. The pathogen has been considered as a potential source of contamination of raw milk and dairy products. This research was aimed to investigate prevalence of ...
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Listeria monocytogenes as one of the most important pathogen in public health concerns is transmitted through consumption of contaminated food. The pathogen has been considered as a potential source of contamination of raw milk and dairy products. This research was aimed to investigate prevalence of L. monocytogenes in raw milk in Kerman region. In the summer of 2011, a total number of one hundred raw milk samples were collected from bulk tanks of some dairy farms and tested foriap and actA genes using polymerase chain reaction. Among the 100 samples, five isolates (5.0%) were detected as L. monocytogenes based on phenotypic and genotypic characteristics. Considering the low frequency of L. monocytogenes in this study, raw milk cannot be omitted as a potential source of food contamination for the population of the region. To achieve more accurate isolation, identification and control of L. monocytogenes in raw milk, it is suggested that new standard laboratory methods be implemented as well as biosafety outreach programs, management techniques and education.
Poultry
Tayebeh Zeinali; Abdollah Jamshidi; Saeid Khanzadi; Mohammad Azizzadeh
Volume 6, Issue 2 , June 2015, , Pages 173-176
Abstract
Listeria monocytogenes can be found throughout the environment and in many foods. It is associated primarily with meat and animal products. Listeria monocytogenes has become increasingly important as a food-borne pathogen. The aim of this study was to evaluate the effect of microwave (MW) treatment of ...
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Listeria monocytogenes can be found throughout the environment and in many foods. It is associated primarily with meat and animal products. Listeria monocytogenes has become increasingly important as a food-borne pathogen. The aim of this study was to evaluate the effect of microwave (MW) treatment of chicken meat samples which were inoculated with L. monocytogenes. Drumettes of broiler carcasses were soaked in fully growth of L. monocytogenes in Brain-Heart Infusion broth. The swab samples were taken from the inoculated samples, after various times of radiation (10, 20, 30, 40, 50, 60, 70 and 80 sec), using a domestic MW oven at full power. Following exposures, viable counts and surface temperaturemeasurements were performed. The bacterial counts were performed on Oxford agar. The results indicated that equal or longer than 60 sec exposures of chicken portions to MW heating which enhances the median surface temperature more than 74 ˚C could eliminate the superficial contamination of chicken meat with L. monocytogenes. Statistical analysis showed samples with equal or longer than 60 sec exposures to MW heating had significant decrease in population of inoculated bacteria compared with positive control group(p < 0.05). Pearson correlation showed a significant correlation between the bacterial population and temperature of samples due to MW exposure (p < 0.001, r = – 0.879 and r2 = 0.773).
Hassan Hassanzadazar; Ali Ehsani; Karim Mardani
Volume 5, Issue 3 , July 2014, , Pages 169-175
Abstract
Viability of probiotic bacteria in food during maintenance and time of consuming in food has become a challenge in food hygiene and technology and is important for representing their beneficial health effects. The aim of this study was to determine the survival of probiotic Enterococcus faecium derived ...
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Viability of probiotic bacteria in food during maintenance and time of consuming in food has become a challenge in food hygiene and technology and is important for representing their beneficial health effects. The aim of this study was to determine the survival of probiotic Enterococcus faecium derived from Koopeh cheese added to industrial Iranian ultra-filtrated (UF) cheese and screening for antimicrobial activity of Enterococcus faecium against Listeria monocytogenes during two months of cheese ripening. Physiochemical and standard microbial methods were used for isolation of Enterococcus strains in cheese samples. The initial number of lactic acid bacteria (LAB) as starter culture was 6 Log g-1 in control samples. The counts started to decrease slightly after day seven (p < 0.05) and dropped to 5 Log g-1 at the end of 60 days. The count of LAB in the test groups decreased to 11 Log g-1 on the day 60 of ripening. The number of Enterococcus faecium was 6 Log g-1 on the day 60. The count of Listeria monocytogenes after 60 days of ripening in blank sample decreased 1 Log but in test samples with protective strain decreased 3 Log in 30 days and reached to zero at 45 days. There were not significant (p < 0.05) changes in chemical parameters such as fat, protein and total solid of UF cheese treatment groups. The results showed that Enterococcus faecium of Koopeh cheese was suitable for development of an acceptable probiotic UF cheese and could be adapted to industrial production of UF cheese.
Razzaqh Mahmoudi; Hossein Tajik; Ali Ehsani; Payman Zare
Volume 3, Issue 3 , September 2012, , Pages 193-197
Abstract
Increasing incidence of food-borne disease along with its social and economic consequences have led to conducting extensive research in order to produce safer food and develop new antimicrobial agents; among them, extensive use of probiotics and bacteriocins as biological additives is of significant ...
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Increasing incidence of food-borne disease along with its social and economic consequences have led to conducting extensive research in order to produce safer food and develop new antimicrobial agents; among them, extensive use of probiotics and bacteriocins as biological additives is of significant importance. The aim of the present study was to evaluate the interactions (growth behavior and survival) of Listeria monocytogenes and Lactobacillus acidophilus in various stages of production, ripening and storage of Iranian white cheese. Changes in pH values at different stages of cheese ripening, along with changes in organoleptic properties of cheese were also assessed. Compared to other treatments, in the treatment of cheese with probiotic agent without starter, the most significant decrease in Listeria monocytogenes count at the end of ripening stage was observed (3.16 Log per gram cheese compared with the control group) (p < 0.05). Survival of probiotic bacteria in control samples of cheese were significantly higher when compared to cheese sample contaminated with Listeria (p < 0.05). White probiotic cheese with starter had the highest of sensory acceptability (p < 0.05). Listeria Monocytogenes count decreased during ripening period of probiotic white cheese but the bacteria survived in probiotic white cheese. Lactobacillus acidophilus count decreased during ripening period of white cheese but it did not lower to less than 106 CFU per g at the end of ripening and storage periods.
