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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #301170
Title: Comparison of the growth of Escherichia coli O157: H7 and O104: H4 during sprouting and microgreen production from contaminated radish seeds

Author
item XIAO, ZHENLEI - University Of Maryland
item Nou, Xiangwu
item LUO, YAGUANG - US Department Of Agriculture (USDA)
item WANG, QIN - US Department Of Agriculture (USDA)

Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2014
Publication Date: 6/2/2014
Publication URL: http://handle.nal.usda.gov/10113/61166
Citation: Xiao, Z., Nou, X., Luo, Y., Wang, Q. 2014. Comparison of the growth of Escherichia coli O157: H7 and O104: H4 during sprouting and microgreen production from contaminated radish seeds. Food Microbiology. 44:60-63.

Interpretive Summary: Microgreens are an increasingly popular type of fresh produce where the plants are harvested after the first pair of true leaves have emerged. Although microgreens are similar to sprouts in many ways, they differ in several key aspects in production, and it is unclear whether microgreens should be subjected to the food safety standards applied to sprouts. This study compared the growth of foodborne pathogenic E. coli during sprout and microgreen production. Radish seeds were contaminated with different levels of E. coli and used for sprout and microgreen production. E. coli populations on harvested sprouts were 1000 to 100000 times greater than those on microgreens, although E. coli populations on both sprouts and microgreens were significantly greater than on inoculated seeds. These data indicate that the conditions used to grow microgreens are less amenable to growth of E. coli. This information will be useful to scientists, growers, and regulatory agencies.

Technical 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 and O104: H4 and E. coli populations on the harvested products compared. Both E. coli O157:H7 and O104:H4 proliferated rapidly during sprouting, reaching levels of 5.8 to 8.1 log cfu/g and 5.2 to 7.3 log cfu/g, respectively, depending on the initial inoculation of the seeds (0.8 - 4.6 log cfu/g). 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, at corresponding seeds contamination levels. Although harvested microgreens carried significantly less (P < 0.001) E. coli than the corresponding sprouts, significant proliferation of E. coli O157:H7 and O104:H4 occurred during both sprouting and microgreen growth.