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theses

Fresh cut produce consumption has increased recently due to increase consumer demand and availability. Such products may pose a risk of foodborne disease because the product is frequently consumed raw. This thesis addresses three specific concerns related to fresh cut produce safety: (i) quantification of the cross contamination rates between fresh cut produce and hands (ii) quantification of the cross contamination rates between a variety of fresh produce and surface types using scenarios that differ by cross contamination direction, surface type, produce type, and post inoculation drying time and (iii) quantification of the transfer rates of Escherichia coli O157:H7 between a single inoculated lettuce leaf to non-inoculated lettuce leaves under various washing times. These studies were carried out using a non-pathogenic surrogate (Enterobacter aerogenes) or cocktails of E. coli O157:H7 or Salmonella. Fresh cut produce types used were cantaloupe, carrots, celery, romaine lettuce or watermelon. Surface types used were ceramic, stainless steel, glass, and plastic. When gloved hands were contaminated with E. coli O157:H7 about 30% transferred to carrots, and 10% and 3% to celery and cantaloupe respectively. When carrots and celery were contaminated, about 1% of those bacteria transferred to gloved hands, while inoculated cantaloupe only transferred about 0.3%. Dry food contact surfaces transferred almost 100% of the bacteria present to carrots and watermelon, but transfer from dry surfaces to celery or lettuce were much more variable. Wash water will become contaminated with 90-99% of bacteria originally present on the lettuce leaves, regardless of washing time and each non-inoculated lettuce piece will become contaminated with ~1% of the E. coli O157:H7 originally on the inoculated lettuce. The key observations are that direction of transfer, and moisture play a large role in determining transfer rates, and that a simple wash with tap water may not be sufficient to significantly reduce the microbial load on lettuce, and may result in contamination spread to previously uncontaminated leaves. Understanding the transfer rates to and from fresh cut produce and during washing arising from this work will allow for better risk assessment and management of microbial food safety risks in the home.

ETD_4182

M.A.

Includes bibliographical references

by Dane A. Jensen

http://hdl.rutgers.edu/1782.1/rucore10001600001.ETD.000066834

doi:10.7282/T39Z93NQ

ETD graduate

The author owns the copyright to this work.

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