Effect of Low-Temperature, High-Pressure Treatment on the Survival of Escherichia coli O157:H7 and Salmonella in Unpasteurized Fruit Juices

Abstract

The destructive effect of high pressure (615 MPa) combined with low temperature (15 degrees C) on various strains of Escherichia coli O157:H7 and various serovars of Salmonella in grapefruit, orange, apple, and carrot juices was investigated. The three-strain cocktail of E. coli O157:H7 (SEA13B88, ATCC 43895, and 932) was found to be most sensitive in grapefruit juice (8.34-log reduction) and least in apple juice (0.41-log reductions) when pressurized at 615 MPa for 2 min at 15 degrees C. Correspondingly, no injured survivor was detected in grapefruit and carrot juices under similar treatment conditions. No Salmonella spp. were detected in a 2-min pressure treatment (615 MPa, 15 degrees C) of grapefruit and orange fruit juices. Except for Enteritidis, all four serovars tested in the present study have viability loss of between 3.92- and 5.07-log reductions when pressurized in apple juice at 615 MPa for 2 min at 15 degrees C. No injured cells were recovered from grapefruit and orange juices, whereas the same treatment demonstrated reduction in numbers of Salmonella serovars Agona and Muenchen in apple juices and to a lesser extent with Typhimurium, Agona, and Muenchen in carrot juice. The present study demonstrated that low-temperature, high-pressure treatment has the potential to inactivate E. coli O157:H7 strains and different Salmonella spp. in different fruit juices.

The effect of high pressure processing on the microbial, physical and chemical properties of Valencia and Navel orange juice

“…The enrichment process used in this study was previously shown to be able to detect pressure-injured cells of the selected Salmonella strains (data not shown). Our results showed at least a 7-log 10 inactivation of Salmonella was achieved at 600 MPa, 20 8C for 60 s. Teo, Ravishankar and Sizer (2001) similarly showed a greater than 7-log reduction of 10 individual Salmonella serovars in orange juice with a 615 MPa treatment (60 s, 15 8C). In support of the effectiveness of pressure treatment of orange juice to reduce pathogen load, evidence has emerged in the literature that suggests pressure treatment of bacterial cells can sensitize the cells to acid (Pagan, Jordan, Benito & Mackey, 2001;Linton et al, 1999b;GarciaGraells, Hauben & Michiels, 1998).…”

Comparison of sterilization efficiency of pulsed and continuous UV light using tunable frequency UV system

“…(Yaun, et al, 2003;Teo, Ravishankar, & Sizer, 2001). This phenomenon might be due to different thresholds in different organisms (Chang et al, 1985).…”

Efficiency of high pressure treatment on inactivation of pathogenic microorganisms and enzymes in apple, orange, apricot and sour cherry juices

“…Therefore, in developing pressurization parameters, pressure-resistant strains of bacterial species should be used as serrogates to ensure greater safety of foods. The effect of low temperature, high pressure treatment on the survival of mainly gramnegative foodborne pathogens, E. coli O157:H7 and Salmonella, inoculated in different fruit juices has been reported in literature (Linton, McClements, & Patterson, 1999;Teo, Ravishankar, & Sizer, 2001). It has also been reported that gram-negative bacteria and cells in exponential growth phase, respectively, are more pressure-sensitive than gram-positive bacteria and early stationary phase cells (Hauben, Wuytac, Soontjens, & Michiels, 1996;Kalchayanand, Sikes, Dunne, & Ray, 1998).…”