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