Spinach E coli Study Shows Importance of Colder Refrigeration
A very large and deadly spinach E. coli outbreak hit the United States in September 2006 in which 199 people in 26 states were sickened after eating contaminated, bagged spinach grown in San Benito County, California. Four deaths were linked to the outbreak and 102 people were hospitalized, including 31 who developed life-threatening hemolytic uremic syndrome (HUS).
For most Americans, it came as a shock that something as healthy as spinach could cause fatal disease and illness on such a wide scale. Studies have been done since the outbreak on the clustering of pathogenic bacteria inside sealed plastic bags of leafy green produce.
The most recent study, completed in October 2009 by scientists from USDA’s Agricultural Research Service, evaluated the effect of temperature during storage of bagged spinach inoculated with E. coli O157:H7. The results were instructive on how the grocery industry and consumers should pay attention to refrigeration to reduce the threat of microbiological hazards in bagged greens.
The study by Yaguang Luo, Qiang He, James McEvoy and William Conway found that E. coli O157:H7 can grow significantly on commercially packaged spinach held at 46.4 degrees Fahrenheit (8 C) or above before significant product quality deterioration occurs.
Bagged E. coli spinach held at 53.6 degrees (12 C) supported “significant” growth of the bacteria within only three days of storage and continued to grow with each additional day of storage until the spinach became noticeably deteriorated by Day 9.
When held at 46.4 degrees (8 C), E coli initially grew slowly but bacteria growth was significant after 6 days of storage, the study found.
On the contrary, bagged spinach held at 33.8 degrees and 41 degrees experienced significant declines in E. coli O157:H7 populations within 3 days of storage.
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