title: Selection of surrogate bacteria in place of E. coli O157:H7 and Salmonella Typhimurium for pulsed electric field treatment of orange juice.
abstract: Pulsed electric field (PEF) technology has been used for the inactivation of microorganisms and to prevent flavor loss in liquid foods and beverages in place of thermal pasteurization. When used to pasteurize orange juice, PEF may prevent loss of volatile sensory attributes. Enterohemorrhagic E. coli O157:H7 (EHEC), two strains of Salmonella Typhimurium, and twenty strains of non-pathogenic bacteria were screened for inactivation in orange juice by PEF at 22 and 20kV/cm at 45 and 55 degrees C, respectively. Higher populations of both salmonellae were inactivated (2.81 and 3.54 log CFU/ml) at 55 degrees C, in comparison with the reduction of EHEC (2.22 log). When tested under the same conditions, inactivation of EHEC was slightly greater than that of a non-pathogenic E. coli (NPEC) ATCC 35218 (2.02 log). NPEC was further tested as a surrogate for EHEC by comparing inactivation kinetics at 45, 50 and 55 degrees C at field strengths of between 7.86 and 32.55kV/cm. Statistical comparison of revealed that EHEC and NPEC inactivation curves were homogeneous at outlet temperatures of 45 and 50 degrees C; however, EHEC was slightly more sensitive to PEF than the surrogate NPEC at 55 degrees C. The higher PEF resistance of non-pathogenic E. coli 35218 at 55 degrees C may provide a desirable margin of safety when used in pilot plant challenge studies in place of E. coli O157:H7.
authors.affiliation: Food Safety Intervention Technologies Research Unit, U. S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, United States. joshua.gurtler@ars.usda.gov
authors.forename: Joshua B
authors.initials: JB
authors.lastname: Gurtler
authors.forename: Rebecca B
authors.initials: RB
authors.lastname: Rivera
authors.forename: Howard Q
authors.initials: HQ
authors.lastname: Zhang
authors.forename: David J
authors.initials: DJ
authors.lastname: Geveke
mesh_terms: D001628:Beverages / Q000382:microbiology*; D032084:Citrus sinensis; D004560:Electricity; D004926:Escherichia coli; D019453:Escherichia coli O157; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D005638:Fruit; D007778:Lactobacillus; D050296:Microbial Viability; D012475:Salmonella; D012486:Salmonella typhimurium