title: A novel model to assess the efficacy of steam surface pasteurization of cooked surimi gels inoculated with realistic levels of Listeria innocua.
abstract: Steam surface pasteurization is a promising decontamination technology for reducing pathogenic bacteria in different stages of food production. The effect of the artificial inoculation type and initial microbial load, however, has not been thoroughly assessed in the context of inactivation studies. In order to optimize the efficacy of the technology, the aim of this study was to design and validate a model system for steam surface pasteurization, assessing different inoculation methods and realistic microbial levels. More specifically, the response of Listeria innocua, a surrogate organism of Listeria monocytogenes, on a model fish product, and the effect of different inoculation levels following treatments with a steam surface pasteurization system was investigated. The variation in the resulting inoculation level on the samples was too large (77%) for the contact inoculation procedure to be further considered. In contrast, the variation of a drop inoculation procedure was 17%. Inoculation with high levels showed a rapid 1-2 log decrease after 3-5 s, and then no further inactivation beyond 20 s. A low level inoculation study was performed by analysing the treated samples using a novel contact plating approach, which can be performed without sample homogenization and dilution. Using logistic regression, results from this method were used to model the binary responses of Listeria on surfaces with realistic inoculation levels. According to this model, a treatment time of 23 s will result in a 1 log reduction (for P = 0.1).
authors.affiliation: Nofima, Muninbakken 9-13, Pb 6122, N-9291 Tromsø, Norway; BioTeC - Chemical and Biochemical Process Technology and Control, Department of Chemical Engineering, Katholieke Universiteit Leuven, Leuven, Belgium. Electronic address: Torstein.Skara@nofima.no.
authors.forename: Torstein
authors.initials: T
authors.lastname: Skåra
authors.affiliation: Department of Food Studies & Environmental Health, Faculty of Health Sciences, University of Malta, Msida, Malta.
authors.forename: Vasilis P
authors.initials: VP
authors.lastname: Valdramidis
authors.affiliation: Nofima, Muninbakken 9-13, Pb 6122, N-9291 Tromsø, Norway.
authors.forename: Jan Thomas
authors.initials: JT
authors.lastname: Rosnes
authors.affiliation: BioTeC - Chemical and Biochemical Process Technology and Control, Department of Chemical Engineering, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Estefanía
authors.initials: E
authors.lastname: Noriega
authors.affiliation: BioTeC - Chemical and Biochemical Process Technology and Control, Department of Chemical Engineering, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Jan F M
authors.initials: JF
authors.lastname: Van Impe
mesh_terms: D000818:Animals; D003296:Cooking; D005396:Fish Products / Q000032:analysis / Q000382:microbiology*; D005399:Fishes; D005782:Gels / Q000737:chemistry; D008087:Listeria / Q000254:growth & development*; D050296:Microbial Viability; D061352:Pasteurization / Q000295:instrumentation / Q000379:methods*; D013227:Steam
chemical_list: D005782:Gels; D013227:Steam
keywords: Listeria; Microbial penetration; Realistic inoculum level; Steam surface pasteurization; Surface inoculation; Surimi gel