title: Salmonella Inactivation During Extrusion of an Oat Flour Model Food.
abstract: Little research exists on Salmonella inactivation during extrusion processing, yet many outbreaks associated with low water activity foods since 2006 were linked to extruded foods. The aim of this research was to study Salmonella inactivation during extrusion of a model cereal product. Oat flour was inoculated with Salmonella enterica serovar Agona, an outbreak strain isolated from puffed cereals, and processed using a single-screw extruder at a feed rate of 75 kg/h and a screw speed of 500 rpm. Extrudate samples were collected from the barrel outlet in sterile bags and immediately cooled in an ice-water bath. Populations were determined using standard plate count methods or a modified most probable number when populations were low. Reductions in population were determined and analyzed using a general linear model. The regression model obtained for the response surface tested was Log (NR/NO) = 20.50 + 0.82T - 141.16aw- 0.0039T2+ 87.91aw2(R2= 0.69). The model showed significant (p < 0.05) linear and quadratic effects of awand temperature and enabled an assessment of critical control parameters. Reductions of 0.67 ± 0.14 to 7.34 ± 0.02 log CFU/g were observed over ranges of aw(0.72 to 0.96) and temperature (65 to 100 °C) tested. Processing conditions above 82 °C and 0.89 awachieved on average greater than a 5-log reduction of Salmonella. Results indicate that extrusion is an effective means for reducing Salmonella as most processes commonly employed to produce cereals and other low water activity foods exceed these parameters. Thus, contamination of an extruded food product would most likely occur postprocessing as a result of environmental contamination or through the addition of coatings and flavorings.
authors.affiliation: U.S. Food and Drug Administration, 6502 South Archer Rd., Bedford Park, IL, 60501, U.S.A.
authors.forename: Nathan M
authors.initials: NM
authors.lastname: Anderson
authors.affiliation: U.S. Food and Drug Administration, 6502 South Archer Rd., Bedford Park, IL, 60501, U.S.A.
authors.forename: Susanne E
authors.initials: SE
authors.lastname: Keller
authors.affiliation: U.S. Food and Drug Administration, 6502 South Archer Rd., Bedford Park, IL, 60501, U.S.A.
authors.forename: Niharika
authors.initials: N
authors.lastname: Mishra
authors.affiliation: Inst. for Food Safety and Health (IFSH)/Illinois Inst. of Technology (IIT), 6502 South Archer Rd., Bedford Park, IL, 60501, U.S.A.
authors.forename: Shannon
authors.initials: S
authors.lastname: Pickens
authors.affiliation: U.S. Food and Drug Administration, 6502 South Archer Rd., Bedford Park, IL, 60501, U.S.A.
authors.forename: Dana
authors.initials: D
authors.lastname: Gradl
authors.affiliation: Wenger Manufacturing, Inc., 714 Main St. Sabetha, KS, 66534, U.S.A.
authors.forename: Tim
authors.initials: T
authors.lastname: Hartter
authors.affiliation: Wenger Manufacturing, Inc., 714 Main St. Sabetha, KS, 66534, U.S.A.
authors.forename: Galen
authors.initials: G
authors.lastname: Rokey
authors.affiliation: Wenger Manufacturing, Inc., 714 Main St. Sabetha, KS, 66534, U.S.A.
authors.forename: Christopher
authors.initials: C
authors.lastname: Dohl
authors.affiliation: Wenger Manufacturing, Inc., 714 Main St. Sabetha, KS, 66534, U.S.A.
authors.forename: Brian
authors.initials: B
authors.lastname: Plattner
authors.affiliation: U.S. Food and Drug Administration, 5001 Campus Drive, College Park, MD, 20740, U.S.A.
authors.forename: Stuart
authors.initials: S
authors.lastname: Chirtel
authors.affiliation: Inst. for Food Safety and Health (IFSH)/Illinois Inst. of Technology (IIT), 6502 South Archer Rd., Bedford Park, IL, 60501, U.S.A.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Grasso-Kelley
mesh_terms: D018554:Avena; D015169:Colony Count, Microbial; D002523:Edible Grain / Q000382:microbiology*; D005433:Flour; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D006801:Humans; D019779:Salmonella enterica / Q000254:growth & development* / Q000302:isolation & purification; D013696:Temperature; D014867:Water
chemical_list: D014867:Water
keywords: Salmonella; cereal; extrusion; flour; low water activity; thermal inactivation