title: Survival and inactivation of human norovirus surrogates in blueberry juice by high-pressure homogenization.
abstract: Human noroviruses (HNoV) have been implicated in gastrointestinal outbreaks associated with fresh produce, juices, and ready-to-eat foods. In order to determine the risk of HNoV transmission by contaminated blueberry juice, survival characteristics of cultivable HNoV surrogates (murine norovirus, MNV-1; feline calicivirus, FCV-F9; and bacteriophage MS2) in blueberry juice (pH = 2.77) after 0, 1, 2, 7, 14, and 21 days at refrigeration temperatures (4°C) were studied. High-pressure homogenization (HPH) was studied as a novel processing method for noroviral surrogate inactivation in blueberry juice. Blueberry juice or phosphate-buffered saline (PBS; pH 7.2 as control) was inoculated with each virus, stored over 21 days at 4°C or subjected to HPH, and plaque assayed. FCV-F9 (∼5 log(10) PFU/mL) was undetectable after 1 day in blueberry juice at 4°C. MNV-1 (∼4 log(10) PFU/ml) showed minimal reduction (1 log(10) PFU/mL) after 14 days, with greater reduction (1.95 log(10) PFU/mL; p < 0.05) after 21 days in blueberry juice at 4°C. Bacteriophage MS2 (∼6 log(10) PFU/mL) showed significant reduction (1.93 log(10) PFU/mL; p < 0.05) after 2 days and was undetectable after 7 days in blueberry juice at 4°C. FCV-F9 remained viable in PBS for up to 21 days (2.28 log(10) PFU/mL reduction), while MNV-1 and MS2 survived after 21 days (1.08 and 0.56 log(10) PFU/mL reduction, respectively). Intriguingly, FCV-F9 and bacteriophage MS2 showed reduction after minimal homogenization pressures in blueberry juice (pH = 2.77), possibly due to the combination of juice pH, juice components, and mechanical effects. MNV-1 in blueberry juice was only slightly reduced at 250 (0.33 log(10) PFU/mL) and 300 MPa (0.71 log(10) PFU/mL). Virus surrogate survival in blueberry juice at 4°C correlates well with the ease of HNoV transmission via juices. HPH for viral inactivation in juices is dependent on virus type, and higher homogenization pressures may be needed for MNV-1 inactivation.
authors.affiliation: Department of Food Science and Technology, University of Tennessee, Knoxville, TN 37996-4591, USA.
authors.forename: Katie Marie
authors.initials: KM
authors.lastname: Horm
authors.forename: P Michael
authors.initials: PM
authors.lastname: Davidson
authors.forename: Federico M
authors.initials: FM
authors.lastname: Harte
authors.forename: Doris Helen
authors.initials: DH
authors.lastname: D'Souza
mesh_terms: D000818:Animals; D001628:Beverages / Q000821:virology*; D029798:Blueberry Plants / Q000821:virology*; D017927:Calicivirus, Feline / Q000254:growth & development; D002415:Cats; D002460:Cell Line; D003080:Cold Temperature; D003257:Consumer Product Safety; D005506:Food Contamination / Q000517:prevention & control*; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D006801:Humans; D017909:Levivirus / Q000254:growth & development; D051379:Mice; D029322:Norovirus / Q000254:growth & development*; D011312:Pressure; D010948:Viral Plaque Assay; D038301:Virus Inactivation