title: Comparison of the growth of Escherichia coli O157: H7 and O104: H4 during sprouting and microgreen production from contaminated radish seeds.
abstract: Both sprouts and microgreens are popular tender produce items, typically grown and harvested in indoor facilities which allow a higher degree of control compared to open field production. While sprouts, which have frequently been implicated in foodborne illness outbreaks, are the subject of numerous national and international standards for their production and distribution, there is a lack of data pertaining to the microbiological safety of microgreens. In this study, sprouts and microgreens were produced from radish seeds inoculated with Escherichia coli O157: H7 or O104: H4 and E. coli populations on the harvested products compared to assess the potentials of product contamination from contaminated seeds during sprouting and microgreen production. Both E. coli O157:H7 and O104:H4 grew rapidly during sprouting, reaching levels of 5.8-8.1 log cfu/g and 5.2-7.3 log cfu/g, respectively, depending on the initial inoculation levels of the seeds (1.5-4.6 log cfu/g and 0.8-4.3 log cfu/g on radish seeds, respectively). In comparison, E. coli O157:H7 and O104:H4 populations on harvested microgreens ranged from 0.8 to 4.5 log cfu/g and from 0.6 to 4.0 log cfu/g, respectively. Although harvested microgreens carried significantly less (P < 0.001) E. coli than sprouts germinated from seeds inoculated at the same levels, proliferation of E. coli O157:H7 and O104:H4 occurred during both sprouting and microgreen growth.
authors.affiliation: Environmental Microbial and Food Safety Laboratory, USDA Agricultural Research Service, Beltsville, MD 20705, USA; Department of Nutrition and Food Science, University of Maryland, College Park, MD 20740, USA.
authors.forename: Zhenlei
authors.initials: Z
authors.lastname: Xiao
authors.affiliation: Environmental Microbial and Food Safety Laboratory, USDA Agricultural Research Service, Beltsville, MD 20705, USA. Electronic address: xiangwu.nou@ars.usda.gov.
authors.forename: Xiangwu
authors.initials: X
authors.lastname: Nou
authors.affiliation: Environmental Microbial and Food Safety Laboratory, USDA Agricultural Research Service, Beltsville, MD 20705, USA.
authors.forename: Yanguang
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Department of Nutrition and Food Science, University of Maryland, College Park, MD 20740, USA. Electronic address: wangqin@umd.edu.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
mesh_terms: D004926:Escherichia coli / Q000254:growth & development*; D019453:Escherichia coli O157 / Q000254:growth & development*; D005506:Food Contamination / Q000032:analysis; D031224:Raphanus / Q000254:growth & development / Q000382:microbiology*; D012639:Seeds / Q000254:growth & development* / Q000382:microbiology
keywords: E. coli O104: H4; Escherichia coli O157: H7; Microgreens; Radish seeds; Sprouts