No abstract

Microgreen growing operations are an emerging industry. This study represents the first national survey of microgreen growers in the United States. An online survey, answered by 176 growers, included questions about farm demographics, growing techniques, microgreen varieties grown, and food safety practices. Microgreen growing operations that earned <10,000 USD/year in microgreen revenue (62%) producing microgreens in trays on stacked, artificially lit shelves (40.3%) dominated the response pool.Most farms surveyed opened after 2010 (75%). These farms primarily grow microgreens using peat (17.6%), coco coir (14.2%), or soil (15.3%). Sunflower (28%), peas (27%), and radish (29%) were the most popular microgreen varieties produced. Chi-square tests of association were performed to identify relationships between farm characteristics and food safety practices. Statistically significant relationships were found between growing media testing at least once per year and total number of employees (P = 0.015) and total number of employees who directly handle microgreens (P = 0.001), possibly indicating that larger operations are better equipped to engage in routine quality assurance procedures. Production system type (P = 0.001) and total number of employees (P = 0.011) were associated with pregermination seed disinfection; however, in this instance, smaller operations (i.e., average of four employees) reported seed disinfection more frequently than larger operations. Routine documentation practices were also significantly associated with annual microgreen revenue (P = 0.003), passing a good agricultural practices (GAP) audit (P = 0.001), and number of previous food safety trainings attended (P = 0.001). Overall, this study aims to inform research, outreach, and training efforts on the growing systems, microgreen varieties, and production practices relevant to microgreen safety.

Aims This study measured the survival of Listeria monocytogenes and Salmonella enterica subsp. enterica serovar Javiana over a 10‐day period on four soil‐free cultivation matrix (SFCM) types in the absence of microgreens and fertilizers. Methods and Results Coco coir (CC), a Sphagnum peat/vermiculite mix, Biostrate® and hemp mat samples were inoculated with 3 × 106 CFU per ml bacteria, incubated at room temperature, and analysed on day 0, 1, 3, 6, and 10. Statistically significant differences in pathogen survival were observed across multiple time points for hemp and Biostrate compared to CC, peat and bacteria in phosphate buffered saline (PBS) (P < 0·05). S. Javiana showed greater overall survival compared to Listeria (P < 0·0002). By day 10, S. Javiana persisted at the initial inoculum concentration for hemp and Biostrate while declining by 1–2 log CFU per ml in CC, peat and PBS. Listeria also persisted at the initial concentration in hemp and Biostrate but decreased to 1 log CFU per ml in peat and below the detection limit in CC and PBS. Conclusions Overall, there are survival differences between bacterial pathogens in SFCM used in microgreen production systems. To our knowledge, this is the first comparison of survival among SFCM involving a S. enterica serovar and L. monocytogenes, and the first study comparing CC, Biostrate and hemp. Significance and Impact of the Study Microgreens production systems predominantly utilize soil alternatives, and it is not well‐understood how pathogen transmission risk may be affected by the type of SFCM. The results of this study impact the microgreen industry as media selection may be used to reduce the risk of bacterial pathogen proliferation and transmission to the plant potentially resulting in potential foodborne illness.