title: Surrogates for validation of electron beam irradiation of foods.
abstract: The aim of this study was to identify a potential surrogate to describe the radiation sensitivity of the most common pathogens encountered in fruits. Three pathogens: Escherichia coli O157:H7 933, Listeria monocytogenes ATCC 51414, and Salmonella Poona, and five non-pathogens: E. coli K-12 MG1655, Listeria innocua Seeliger 1983 (NRRL B-33003 and NRRl B-33014), Enterobacter aerogenes, and Salmonella LT2 were inoculated (populations of 10(7)-10(9) CFU/ml) into model food systems (10% w/w gelatin) and exposed to doses up to 1.0 kGy using a 2 MeV Van der Graaf linear accelerator. The non-pathogen E. coli K-12 MG1655 was highly resistant to radiation (D(10)=0.88 kGy) in comparison to the other strains while L. monocytogenes was the more radiation-resistant pathogen (D(10)=1.09 kGy). Thus, E. coli K-12 MG1655 could be a suitable surrogate for e-beam studies with L. monocytogenes as the indicator pathogen. L. innocua strains were more radiation-sensitive (D(10)=0.66, 0.72 kGy) than their pathogenic counterpart. S. Poona and E. coli O157:H7 were even more radiation-sensitive (D(10)=0.38, 0.36 kGy, respectively). S. LT2 was the least radiation-resistant pathogen with D(10)=0.12 kGy. In a later study, the radiation resistance of the pathogens and the surrogate was evaluated when inoculated in a real food (i.e., fresh cantaloupe). The D(10) values obtained in this experiment were higher than those obtained with the model foods. However, the surrogate was still more radiation-resistant and could therefore be used to indicate decontamination of the target pathogens under electron beam irradiation.
authors.affiliation: Department of Biological and Agricultural Engineering, Texas A and M University, College Station, Texas 77843-2117, USA.
authors.forename: Oscar
authors.initials: O
authors.lastname: Rodriguez
authors.forename: M Elena
authors.initials: ME
authors.lastname: Castell-Perez
authors.forename: Nont
authors.initials: N
authors.lastname: Ekpanyaskun
authors.forename: Rosana G
authors.initials: RG
authors.lastname: Moreira
authors.forename: Alejandro
authors.initials: A
authors.lastname: Castillo
mesh_terms: D015169:Colony Count, Microbial; D004307:Dose-Response Relationship, Radiation; D019453:Escherichia coli O157 / Q000254:growth & development / Q000528:radiation effects*; D005514:Food Irradiation / Q000592:standards*; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D005638:Fruit / Q000382:microbiology*; D005720:Gamma Rays; D008089:Listeria monocytogenes / Q000254:growth & development / Q000528:radiation effects*; D012475:Salmonella / Q000254:growth & development / Q000528:radiation effects*; D013997:Time Factors