title: Validation of pepperoni process for control of Shiga toxin-producing Escherichia coli.
abstract: The objective of this study was to compare the survival of non-O157 Shiga toxin-producing Escherichia coli (STEC) with E. coli O157:H7 during pepperoni production. Pepperoni batter was inoculated with 7 log CFU/g of a seven-strain STEC mixture, including strains  of serotypes O26, O45, O103, O111, O121, O145, and O157. Sausages were fermented to pH ≤4.8, heated at 53.3°C for 1 h, and dried for up to 20 days. STEC strains were enumerated at designated intervals on sorbitol MacConkey (SMAC) and Rainbow (RA) agars; enrichments were completed in  modified EC (mEC) broth and nonselective tryptic soy broth (TSB). When plated on SMAC, total E. coli populations decreased 2.6 to 3.5 log after the 1-h heating step at 53.3°C, and a 4.9- to 5-log reduction was observed after 7 days of drying. RA was more sensitive in recovering  survivors; log reductions on it were 1.9 to 2.6, 3.8 to 4.2, and 4.6 to 5.3 at the end of cook, and at day 7 and day 14 of drying, respectively. When numbers were less than the limit of detection by direct plating on days 14 and 20 of drying (representing a 5-log kill), no more than one of  three samples in each experiment was positive by enrichment with mEC broth; however, STEC strains were recovered in TSB enrichment. Freezing the 7-day dried sausage for 2 to 3 weeks generated an additional 1- to 1.5-log kill. Confirmation by PCR revealed that O103 and O157 had the greatest  survival during pepperoni productions, but all serotypes except O111 and O121 were occasionally recovered during drying. This study suggests that non-O157 STEC s trains have comparable or less ability than E. coli O157 to survive the processing steps involved in the manufacture of pepperoni.  Processes suitable for control of E. coli O157 will similarly inactivate the other STEC strains tested in this study.
authors.affiliation: University of Wisconsin-Madison, Food Research Institute, Madison, WI 53706, USA. kglass@wisc.edu
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Glass
authors.forename: Charles W
authors.initials: CW
authors.lastname: Kaspar
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Sindelar
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Milkowski
authors.forename: Brian M
authors.initials: BM
authors.lastname: Lotz
authors.forename: Jihun
authors.initials: J
authors.lastname: Kang
authors.forename: Nancy G
authors.initials: NG
authors.lastname: Faith
authors.forename: Elena
authors.initials: E
authors.lastname: Enache
authors.forename: A I
authors.initials: AI
authors.lastname: Kataoka
authors.forename: Craig
authors.initials: C
authors.lastname: Henry
mesh_terms: D000362:Agar; D000818:Animals; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D003470:Culture Media; D019453:Escherichia coli O157 / Q000145:classification* / Q000254:growth & development* / Q000302:isolation & purification; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control*; D005511:Food Handling / Q000379:methods* / Q000592:standards; D005516:Food Microbiology; D008461:Meat Products / Q000382:microbiology*; D012703:Serotyping; D013696:Temperature; D013997:Time Factors
chemical_list: D003470:Culture Media; D000362:Agar