Salmonella surveillance on fresh produce and inactivation by high hydrostatic pressure

Günel, Elif
In this study, 248 fresh produce samples including tomato, parsley and lettuce (i.e. iceberg and greenleaf lettuce) were collected from supermarkets and local bazaars in Ankara for investigating the presence of Salmonella. Salmonella was detected in 1.2% (3/248) of samples by conventional culturing method with molecular confirmation conducted through polymerase chain reaction (PCR). For further characterization of isolates, serotyping, multilocus sequence typing (MLST) of seven housekeeping genes (aroC, thrA, purE, sucA, hisD, hemD and dnaN) and pulsed-field gel electrophoresis (PFGE) were performed. S. enterica subsp. enterica serotypes Anatum, Charity and Mikawasima were isolated from two parsley samples and one lettuce sample respectively. MLST resulted in 3 sequence types (STs) for our isolates, including one novel ST for serotype Mikawasima. Similarly, PFGE revealed three different XbaI PFGE patterns. The effect of high hydrostatic pressure (HHP) treatment on the viability of Salmonella isolates, artificially inoculated onto fresh produce samples which they were isolated from, was evaluated at 500 MPa for 5 min at 25oC. Salmonella was not detected in any of the HHP treated samples. Shelf life analysis (7 days at 25oC and 4oC) revealed growth only for serotype Anatum which was stored at 25oC, thus indicating the presence of injured cells after HHP treatment. The results of this survey, obtained by the most common subtyping methods (i.e. serotyping, MLST and PFGE) worldwide, contributes to the development of national database in Turkey, which is essential for investigating evolutionary pathways, geographical distribution and genetic diversity of Salmonella strains. In addition, in this study HHP treatment, as an alternative technique to heat processing, represents an applicable tool for control of Salmonella in fresh produce.


Surveillance study of salmonella in fresh peppers (capsicum annuum l.) and inactivation by high hydrostatic pressure treatment
Polat Kılıç, Özlem Gözde; Alpas, Hami; Soyer, Yeşim; Department of Food Engineering (2014)
The main objective of this study was to investigate distribution of Salmonella in fresh peppers in Turkey. To serve this purpose, a total of 255 fresh pepper samples (green, kapya, bell, mazamort and charleston) were collected from 3 districts within 9 supermarkets and 3 bazaars in Ankara, Turkey. Salmonella suspected colonies was confirmed by using polymerase chain reaction (PCR) of Salmonella specific gene, invA. One of isolate was assigned as Salmonella, which was isolated from kapya pepper. Confirmed Sa...
Salmonella surveillance on fresh produce in retail in Turkey
Gunel, Elif; Kilic, Gozde Polat; Bulut, Ece; Durul, Bora; Acar, Sinem; Alpas, Hami; Soyer, Yeşim (2015-04-16)
Although Turkey is one of the major producers of fruits and vegetables in the world, there has been no information available on the prevalence of pathogens in fresh produce. To fill this gap, we collected 503 fresh produce samples including tomato, parsley, iceberg lettuce, green-leaf lettuce and five different fresh pepper varieties (i.e., green, kapya, bell, mazamort and Charleston) from 3 major districts within 9 supermarkets and 3 bazaars in Ankara, Turkey to investigate the presence of Salmonella. Salm...
Mathematical analysis of peeling of carrots
Aydın, Özlem; Adalı, Orhan; Department of Food Engineering (2005)
In this study, carrots of Beypazarı variety, cultivated during 2004 season were chemically and steam peeled. Effects of temperature, concentration of NaOH solutions and immersion time on lye peeling of carrots were studied; optimum time-temperature-concentration relations were analyzed mathematically. Then suitable combinations of concentration, temperature and time were determined just by considering degree of peeling. Increases in both temperature and concentration of lye solution led to a decrease in pee...
Microbial growth and attachment of Salmonella and enterohemorrhagic and enteroaggregative Escherichia coli strains on cress microgreens grown in peat soil system
Namlı, Şahin; Samut, Hilal; Soyer, Yeşim (2021-12-01)
Purpose This study aimed to investigate how enteric pathogens and their biofilm populations on fresh produce survive according to time that contamination has occurred on leaves and contamination route: seed irrigation water. Design/methodology/approach Cress was contaminated in two different ways: contamination of seeds and irrigation water with 8-log MPN/mL bacterial load, Salmonella Newport, Escherichia coli O157:H7, O104:H4 or O78:H2. While contaminated seeds were cultivated for seed contamination, conta...
Subtyping of salmonella isolated from human clinical and animal non-clinical cases, as well as different food samples using pulsed field gel electrophoresis (PFGE) /
Bulut, Ece; Soyer, Yeşim; Özcengiz, Gülay; Department of Biotechnology (2014)
Salmonella is one of the most reported pathogens in foodborne outbreaks worldwide. In order to ensure safety of foods, farm-to-fork surveillance and control systems must be utilized. Development of numerous typing methods have improved the ability to detect salmonellosis outbreaks, enabling to trace the contaminated source from farm to fork. Facilitating prevention and regulation of techniques, knowledge of the epidemiology, genetics and ecology of Salmonella infections depend on the information provided by...
Citation Formats
E. Günel, “Salmonella surveillance on fresh produce and inactivation by high hydrostatic pressure,” M.S. - Master of Science, Middle East Technical University, 2014.