Asi̇de Adapte Ve Adapte Olmayan Durağan Faz Escherichia Coli O157:H7, Salmonella Typhimurium Ve Listeria Monocytogenes’İn Nar Suyundaki̇ Canli Kalma Süreleri̇ni̇n Beli̇rlenmesi̇ (original) (raw)
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The survival of Escherichia coli O157:H7 in acidic foods and its enhanced survival in refrigerated acid foods are well documented. This prompted the present study to evaluate the growth potential of E. coli O157:H7 in fresh tropical fruit juices. The pH of the various juices ranged between 3.57 (pineapple) and 6.2 (avocado). Samples were separately inoculated with a mixture of four E. coli O157:H7 strains at initial levels of approximately 10 3 cfu/ml, and stored at refrigeration (48C) and ambient (20 Á/258C) temperatures for 120 h. In pineapple juice, some decline in count was noted during ambient temperature storage but complete inhibition was not observed. At refrigeration temperature, the test strains survived without a noticeable decline in number. The pH remained unchanged throughout the experiment at both incubation temperatures. In papaya and avocado juices, counts of the test strains increased at varying rates at both storage temperatures. A decrease in pH was also noted in the stored juice. This study demonstrated that E. coli O157:H7 can survive well in acidic pineapple juice at both incubation temperatures and could also grow luxuriously in fruit juices with relatively higher pH values ( /5.7) when stored at ambient and refrigeration temperatures.
International journal of food sciences and nutrition, 2005
The survival of Escherichia coli O157:H7 in acidic foods and its enhanced survival in refrigerated acid foods are well documented. This prompted the present study to evaluate the growth potential of E. coli O157:H7 in fresh tropical fruit juices. The pH of the various juices ranged between 3.57 (pineapple) and 6.2 (avocado). Samples were separately inoculated with a mixture of four E. coli O157:H7 strains at initial levels of approximately 10(3) cfu/ml, and stored at refrigeration (4 degrees C) and ambient (20-25 degrees C) temperatures for 120 h. In pineapple juice, some decline in count was noted during ambient temperature storage but complete inhibition was not observed. At refrigeration temperature, the test strains survived without a noticeable decline in number. The pH remained unchanged throughout the experiment at both incubation temperatures. In papaya and avocado juices, counts of the test strains increased at varying rates at both storage temperatures. A decrease in pH wa...
Survival of Listeria Monocytogenes in Tomato Juice at 5 and 30°C Storage
Current research in nutrition and food science
Listeria monocytogenes is a food-borne pathogen and has been associated with a variety of food products including fruits and vegetables, which are important for a healthy human diet. L. monocytogenes survives and grows at low temperatures and thus it can be multiplied to dangerous levels in a product which is kept at refrigeration temperatures. This work examines the ability of L. monocytogenes to survive, in a product of high consumption frequency, such as tomato juice, in correlation to storage temperature. The results indicate that a significant number of cells survived in tomato juice whether the storage temperature was 30°C or 5°C, although the refrigerator temperature slightly reduces the survival of L. monocytogenes cells. An understanding of the cold stress response of the pathogen will be helpful in the design of effective methods to control L. monocytogenes in freezing foods in order to provide consumers with a safe product.
Food Control, 2009
The aim of this work was to study the growth/survival of acid-adapted cells of Listeria monocytogenes, in orange juice and in minimally processed orange slices. The L. monocytogenes OML 45 behaviour into TSB (Tryptic Soy Broth) medium was evaluated at different pH values (between 3.7 and 6.7). The acid-adapted cells were obtained maintaining L. monocytogenes in TSB at pH 5.7 for 3 h. The obtained cells were then inoculated into a diluted orange juice with a pH of 2.6. Moreover, the acid-adapted cells were inoculated into minimally processed orange slices. The growth was evaluated during storage at different temperatures. The study confirms that orange juice and minimally processed orange slices can support the acid-adapted pathogen growth.
Food Microbiology, 2010
Consumption of fresh-cut produce has sharply increased recently causing an increase of foodborne illnesses associated with these products. As generally, acidic fruits are considered 'safe' from a microbiological point of view, the aim of this work was to study the growth and survival of Escherichia coli O157:H7, Salmonella and Listeria innocua on minimally-processed peaches. The three foodborne pathogens population increased more than 2 log 10 units on fresh-cut peach when stored at 20 and 25 C after 48 h. At 10 C only L. innocua grew more than 1 log 10 unit and it was the only pathogen able to grow at 5 C. Differences in growth occurred between different peach varieties tested, with higher population increases in those varieties with higher pH ('Royal Glory' 4.73 AE 0.25 and 'Diana' 4.12 AE 0.18). The use of common strategies on extending shelf life of fresh-cut produce, as modified atmosphere packaging and the use of the antioxidant substance, ascorbic acid (2% w/v), did not affect pathogens' growth at any of the temperatures tested (5 and 25 C). Minimally-processed peaches have shown to be a good substrate for foodborne pathogens' growth regardless use of modified atmosphere and ascorbic acid. Therefore, maintaining cold chain and avoiding contamination is highly necessary.
International Journal of Food Sciences and Nutrition
The survival of Escherichia coli O157:H7 in acidic foods and its enhanced survival in refrigerated acid foods are well documented. This prompted the present study to evaluate the growth potential of E. coli O157:H7 in fresh tropical fruit juices. The pH of the various juices ranged between 3.57 (pineapple) and 6.2 (avocado). Samples were separately inoculated with a mixture of four E. coli O157:H7 strains at initial levels of approximately 10 3 cfu/ml, and stored at refrigeration (48C) and ambient (20 Á/258C) temperatures for 120 h. In pineapple juice, some decline in count was noted during ambient temperature storage but complete inhibition was not observed. At refrigeration temperature, the test strains survived without a noticeable decline in number. The pH remained unchanged throughout the experiment at both incubation temperatures. In papaya and avocado juices, counts of the test strains increased at varying rates at both storage temperatures. A decrease in pH was also noted in the stored juice. This study demonstrated that E. coli O157:H7 can survive well in acidic pineapple juice at both incubation temperatures and could also grow luxuriously in fruit juices with relatively higher pH values ( /5.7) when stored at ambient and refrigeration temperatures.
Journal of Food Protection, 2001
The adaptation of Escherichia coli O157:H7 cells to acid conditions has been reported. This study showed the behavior of three strains of E. coli O157:H7 in two different physiological stages (acid shocked and control cells), inoculated in five fruit pulps stored at 4°C for up to 30 days. The three strains of E. coli O157:H7 inoculated in grape pulp could be recovered up to day 30. E. coli O157:H7 strains survived for 4 days in all fruit pulps tested with different pH values (2.51 to 3.26), with the exception of acid-shocked cells of E. coli O157:H7 strain 933, which did not survive in “cajá” (Spodias lutea L.) pulp. The results clearly indicated that acid resistance can persist for long periods during storage at 4°C. The protection conferred by acid adaptation suggests that acid-resistant organisms will be better equipped to outlast these acid challenges. The survival of E. coli O157:H7 in fruit pulps with a low pH, stored under refrigeration, is of extreme importance due to the hi...
Food Control, 2017
This study aimed to assess the effect of storage temperature and fruit matrix on the survival of L. monocytogenes after a gastrointestinal simulation. The growth of L. monocytogenes on different matrices (fresh-cut pear and melon and synthetic growth medium as a control) and storage temperature (1, 5, 10 and 20 °C) was evaluated. Subsequently, the ability of the pathogen on different fruit matrices to overcome the gastrointestinal simulation was evaluated. The highest reduction in the population of L. monocytogenes on fresh-cut pear and melon subjected to the gastrointestinal simulation was after 6 days of storage at 5 °C (0.84 and 2.12 log reduction on the pear and melon, respectively). Conversely, higher survival ratios of L. monocytogenes in both matrices were observed at 1 °C, even with logarithmic increases after the whole gastrointestinal simulation during the experiment. At 20 °C, the survival capacity of L. monocytogenes was higher than that under storage at 5 and 10 °C when grown on fresh-cut pear, whereas this was not observed on fresh-cut melon. In general, under the proper storage temperature of fresh-cut fruit (5 °C) and after 1 day of storage, the L. monocytogenes on the melon was more sensitive than that on the pear, and this behaviour was maintained for up to 9 days. The ability of L. monocytogenes to overcome the gastrointestinal tract was not enhanced when the pathogen grew on fresh-cut pear and melon under the proper storage temperature.
Behavior of Listeria Monocytogenes and Escherichia Coli O157:H7 in Fresh-Sliced Cactus-Pear Fruit
Journal of Food Safety, 2005
Storage experiments were conducted to follow the behavior of Listeria monocytogenes and Escherichia coli O157:H7, deliberately inoculated on fresh-cut cactus-pear fruits before packaging under modified and control atmosphere and stored at four different temperatures (4, 8, 12 and 20C). L. monocytogenes was able to proliferate during storage at different temperature both in control and modified atmosphere. By comparing the sanitary-risk values with those of shelf life, it is possible to conclude that the storage of cactus-pear samples at temperatures greater than 4C, both in control and in modified atmospheres, could lead to a significant health-time risk, and that this is strictly affected by temperature. E. coli O157:H7 was able to proliferate only in the sample stored at 4 and 8C in both package atmospheres. On the contrary, this species was completely suppressed at the higher temperatures. In our study, E. coli O157:H7 appeared to be much less suited for survival on the surface of the fruit than L. monocytogenes.
International Journal of Food Microbiology, 2012
In this study the survival and growth patterns of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in various concentrations of black carrot juice were investigated during incubation period at 4°C and 37°C for 7 days. Several parameters, such as juice concentration (%), pH, incubation temperature (°C) and time (days) were found effective on the survival of pathogens tested. Although L. monocytogenes has been found to be the less resistant microorganism to the variable conditions, there were only ca. 1 and 2 log reductions in the number of the cells in the juice samples incubated at 4°C for 2 and 7 days, respectively. Incubating at low temperature (4°C) enhanced the survival of test microorganisms.