Date of Graduation

5-2020

Document Type

Thesis

Degree Name

Master of Science in Cell & Molecular Biology (MS)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Kristen E. Gibson

Committee Member

Jyotishka Datta

Second Committee Member

Mary C. Savin

Third Committee Member

Steven C. Ricke

Keywords

Listeria, microgreens, safety, Salmonella, sunflower, survey

Abstract

Microgreens are immature sprouts of edible plants, sharing some similarities with sprouted seeds and petite leafy greens. Since they are most often grown in containers in buildings or greenhouses, they present a new area for food safety research at the intersection of the built environment and produce farming. Contamination by human pathogens has been extensively studied in other types of produce typically eaten raw, including sprouted seeds, which have been implicated in numerous outbreaks of salmonellosis over the last several decades. There is a paucity of knowledge about the microgreen sector of the fresh-cut industry; thus, it was determined that a survey of operational details, microgreen varieties grown, and food safety practices would be needed to determine research directions. Following a nationwide survey of US-based microgreen farmers, two laboratory experiments were conducted using the most common production system type and microgreen varieties. Soil-free growing media (SFGM) was inoculated with Listeria monocytogenes FSL R2-574 and Salmonella enterica Javiana in a plant-free bench scale experiment as well as during cultivation of sunflower microgreens in a fully indoor, artificially lit, stacked track system similar to that of the microgreen farmers surveyed. It was found that the type of SFGM influenced survival of these two pathogens, which are commonly associated with sprouted seed outbreaks as well as several recent microgreen product recalls. Furthermore, it was found that survival of these pathogens was enhanced in the presence of the microgreen root environment. These results are important for informing system design decisions by microgreen farmers.

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