Rapid concentration/detection of Escherichia coli O157:H7 and Listeria monocytogenes from lettuce wash water
Gustafson, Ryann Elizabeth
author
Ryser, Elliot
thesis advisor
Linz, John
degree committee member
Rose, Joan
degree committee member
text
Text
Theses
No place, unknown, or undetermined
2017
2017
eng
English
application/pdf
xiii, 123 pages
"Dead-end ultrafiltration concentration (DEUF-C) prior to qPCR or standard enrichment was used to determine presence/absence of Escherichia coli O157:H7 (Ec) and Listeria monocytogenes (Lm) in various lettuce wash waters generated using both a pilot- and commercial scale processing line. After inoculating and pilot-scale processing of the ice berg lettuce, 8 of 24 (33%) of Ec and Lm samples were positive by DEUF-C, but negative by commercial FDA BAM. In addition, populations of both pathogens were significantly higher in DEUF-C samples compared to unconcentrated samples after 7 h of enrichment (P < 0.05). Using the commercial-scale processing line, 14 of 14 (100%) samples yielded Ec and Lm using DEUF-C compared to 1 of 15 (6.7%) and 3 of 15 (20%) wash water grab samples, respectively. Higher total filterable volumes were achieved for flume (30.6 + 9.9 L) compared to centrifugation water (9.9 + 2.0 L) (P < 0.05). Ec and Lm were also detected in 16 of 16 (100%) DEUF-C samples compared to 2 of 18 (11.1%) and 3 of 18 (16.7%) grab samples, respectively, from a commercial-scale test facility. These studies indicate that DEUF-C can detect lower levels of Ec and Lm in lettuce wash water compared to standard culture methods. However, the filtration times and total filterable volumes will need to be further improved for commercial produce wash and centrifugation water containing high organic loads."--Page ii.
by Ryann Elizabeth Gustafson
Thesis (M.S.)--Michigan State University. Food Science, 2017
Includes bibliographical references (pages 110-123)
Ultrafiltration
Lettuce
Processing
Food adulteration and inspection
Escherichia coli
Listeria monocytogenes
Ultrafiltration
Listeria monocytogenes
Food adulteration and inspection
Escherichia coli
Food science
Lettuce
Electronic Theses & Dissertations
etd
9781369732795
1369732791
1027790641
10271909
Gustafson_grad.msu_0128N_15176
In Copyright
https://doi.org/doi:10.25335/tbek-k566
aacr
MiEM
Michigan State University. Libraries
2019-12-02
2024-03-02
1027790641
Converted from MARCXML to MODS version 3.7 using a custom XSLT.
eng