title: Effect of high pressure treatment on the survival of Shiga toxin-producing Escherichia coli in strawberry puree.
abstract: Most fresh produce, such as strawberries, receives minimal processing and is often eaten raw. Contamination of produce with pathogenic bacteria may occur during growth, harvest, processing, transportation, and storage (abuse temperature) and presents a serious public health risk. Strawberries have been implicated in an outbreak of Escherichia coli O157:H7 infection that sickened 15 people, including one death. Strawberries may also be contaminated by other serogroups of non-O157 Shiga toxin-producing E. coli (STEC), including O26, O45, O103, O111, O121 and O145, which have become known as the "Big Six" or "Top Six" non-O157 STECs. The objective of this research was to explore the potential application of high pressure processing (HPP) treatment to reduce or eliminate STECs in fresh strawberry puree (FSP). FSP, inoculated with a six-strain cocktail of the "Big Six" non-O157 STEC strains or a five-strain cocktail of E. coli O157:H7 in vacuum-sealed packages, were pressure-treated at 150, 250, 350, 450, 550, and 650 MPa (1 MPa = 10(6) N/m(2)) for 5, 15, and 30 min. HPP treatment, at 350 MPa for ≥5 min, significantly reduced STECs in FSP by about 6-log CFU/g from the initial cell population of ca. 8-log CFU/g. Cell rupture, observed by scanning electron microscopy (SEM), demonstrated that the HPP treatments can be potentially used to control both non-O157 and O157:H7 STECs in heat sensitive products.
authors.affiliation: Institute of Food Science and Technology, National Taiwan University, Taipei 106, Taiwan; Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA.
authors.forename: HsinYun
authors.initials: H
authors.lastname: Hsu
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA. Electronic address: shiowshuh.sheen@ars.usda.gov.
authors.forename: Shiowshuh
authors.initials: S
authors.lastname: Sheen
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Sites
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA.
authors.forename: Lihan
authors.initials: L
authors.lastname: Huang
authors.affiliation: Institute of Food Science and Technology, National Taiwan University, Taipei 106, Taiwan. Electronic address: jsbwu@ntu.edu.tw.
authors.forename: James Swi-Bea
authors.initials: JS
authors.lastname: Wu
mesh_terms: D003257:Consumer Product Safety; D005506:Food Contamination / Q000032:analysis; D005519:Food Preservation / Q000295:instrumentation / Q000379:methods*; D031985:Fragaria / Q000737:chemistry / Q000382:microbiology*; D005638:Fruit / Q000737:chemistry / Q000382:microbiology*; D050296:Microbial Viability; D011312:Pressure; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification
keywords: High pressure processing; Shiga toxin-producing Escherichia coli; Strawberry puree