title: Nonthermal inactivation of norovirus surrogates on blueberries using atmospheric cold plasma.
abstract: Viruses are currently the leading cause of foodborne outbreaks, most of which are associated with foods consumed raw. Cold plasma (CP) is an emerging novel nonthermal technology that can be used to surface decontaminate foods. This study investigated CP technology for the nonthermal inactivation of human norovirus surrogates, Tulane virus (TV) and murine norovirus (MNV), on the surface of blueberries. Blueberries (5 g) were weighed into sterile 4 oz. glass jars and inoculated with TV, 5 log PFU/g. Samples were treated with atmospheric CP for 0, 15, 30, 45, and 60 s at a working distance of 7.5 cm with 4 cubic feet/minute (cfm) of CP jet. Temperature readings were taken with an infrared camera prior to, and immediately following, CP treatments. In order to establish the impact of air flow during CP treatment (4 cfm), an additional 7 cfm jet of room temperature air was introduced from a separate nozzle. The experiment was repeated with 90 and 120 s as additional treatment time points. Viral titers were measured immediately after each treatment with a plaque assay using LLC-MK2 cells (TV) or RAW 264.7 cells (MNV). TV was significantly reduced 1.5 PFU/g compared to the control after treatment time of 45s, which was achieved regardless of temperature conditions. With the addition of 7 cfm of ambient air, the maximum log reduction for TV was 3.5 log PFU/g after 120s of treatment. MNV was significantly reduced by 0.5 log PFU/g compare to the control at 15s, and further treatment of MNV with ambient air brought the log reduction to greater than 5 log PFU/g at 90 s of treatment (Fig. 3). These results demonstrate that CP viral inactivation does not rely on thermal inactivation, and is therefore nonthermal in nature. With further optimization, CP may be used by food processors as a means of nonthermal inactivation of foodborne viruses.
authors.affiliation: National College of Natural Medicine, 014 SE Porter St., Portland, OR 97201, USA.
authors.forename: Alison
authors.initials: A
authors.lastname: Lacombe
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Food Safety and Intervention Technologies Research Unit, Eastern Regional Research Center, 600 Mermaid Ln, Wyndmoor, PA 19038, USA. Electronic address: Brendan.Niemira@ars.usda.gov.
authors.forename: Brendan A
authors.initials: BA
authors.lastname: Niemira
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Food Safety and Intervention Technologies Research Unit, Eastern Regional Research Center, 600 Mermaid Ln, Wyndmoor, PA 19038, USA.
authors.forename: Joshua B
authors.initials: JB
authors.lastname: Gurtler
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Food Safety and Intervention Technologies Research Unit, Eastern Regional Research Center, 600 Mermaid Ln, Wyndmoor, PA 19038, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Sites
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Food Safety and Intervention Technologies Research Unit, Eastern Regional Research Center, 600 Mermaid Ln, Wyndmoor, PA 19038, USA.
authors.forename: Glenn
authors.initials: G
authors.lastname: Boyd
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Food Safety and Intervention Technologies Research Unit, Delaware State University, Dover, DE 19901, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Kingsley
authors.affiliation: Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI 54601, USA.
authors.forename: Xinhui
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Animal and Food Sciences, University of Delaware, 020 Townsend Hall, Newark, DE 19716, USA.
authors.forename: Haiqiang
authors.initials: H
authors.lastname: Chen
mesh_terms: D000818:Animals; D029798:Blueberry Plants / Q000821:virology*; D002139:Caliciviridae / Q000502:physiology*; D005516:Food Microbiology; D059022:Food Safety / Q000379:methods; D006801:Humans; D051379:Mice; D029322:Norovirus / Q000502:physiology*; D058626:Plasma Gases; D013696:Temperature; D010948:Viral Plaque Assay; D038301:Virus Inactivation
chemical_list: D058626:Plasma Gases
keywords: Blueberries; Cold plasma; Food safety; Inactivation; Norovirus; Surrogate