Selection of surrogate bacteria in place of E. coli O157:H7 and Salmonella Typhimurium for pulsed electric field treatment of orange juice

• Published in: International journal of food microbiology 2010-04, Vol.139 (1-2), p.1-8
• Main Authors: Gurtler, Joshua B, Rivera, Rebecca B, Zhang, Howard Q, Geveke, David J
• Format: Article
• Language: English
• Subjects: bacterial contamination; Beverages; Beverages - microbiology; Biological and medical sciences; Citrus; Citrus sinensis; Electricity; Escherichia coli; Escherichia coli O157; Escherichia coli O157:H7; food contamination; Food industries; Food Microbiology; Food Preservation - methods; food processing; food processing quality; Fruit; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Lactobacillus; Microbial Viability; model food systems; nonthermal processing; orange juice; pasteurization; pathogen survival; pulsed electric field treatment; pulsed electric fields; Salmonella; Salmonella typhimurium; surrogate bacteria
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2010.02.023

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°C, respectively. Higher populations of both salmonellae were inactivated (2.81 and 3.54 log CFU/ml) at 55°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°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°C; however, EHEC was slightly more sensitive to PEF than the surrogate NPEC at 55°C. The higher PEF resistance of non-pathogenic E. coli 35218 at 55°C may provide a desirable margin of safety when used in pilot plant challenge studies in place of E. coli O157:H7.