Skip to main content

Postprocess Contamination of Flexible Pouches Challenged by In Situ Immersion Biotest

Buy Article:

$37.00 plus tax (Refund Policy)


Packages were evaluated for leaks by determining microbial penetration through microchannels as a function of test organism concentration, location in a retort, and microchannel diameter and length. A flexible pouch was used in an in situ immersion biotest coupled with a state-of-the-art retort. Microchannel diameters of 10 to 661 μm with 3- and 6-mm lengths were created by placing tungsten wires in vacuum heat-sealed flexible pouches. After removing the wires, these pouches were subsequently heat processed under pressure. They were then biotested in cooling water containing 103 and 106 CFU of motile Enterobacter aerogenes per ml for 30 min and were dried immediately after manual unloading. After incubation at 37°C for 3 days, they were visually examined for contamination. The high-temperature retorting process was shown to decrease microchannel diameters by an average of 20%. Generally, the smaller the microchannel diameter, the greater the percent shrinkage. Statistical analysis of the biotesting data showed that microchannel diameter and length had strong effects on microbial penetration (P < 0.01). Microbial concentration had a borderline significant effect (P < 0.05), but the effect of package location in the retort was not significant. At conservative conditions, such as a 3-mm microchannel length and a cooling water contamination level of 106 CFU/mI, the selected microorganism can penetrate microchannels with diameters as small as 7 μm. However, the minimum microchannel diameter for penetration could be as large as 46 μm at practical conditions of 6-mm microchannellength and contamination levels of 103 CFU/ml.

Document Type: Research Article

Affiliations: Division of Food Processing and Packaging, U.S. Food and Drug Administration, National Center for Food Safety and Technology, 6502 South Archer Road, Summit-Argo, Illinois 60501, USA

Publication date: December 1, 1998

More about this publication?
  • IAFP Members with personal subscriptions to JFP Online: To access full-text JFP or JMFT articles, you must sign-in in the upper-right corner using your Ingenta sign-in details (your IAFP Member Login does not apply to this website).

    The Journal of Food Protection (JFP) is a refereed monthly publication. Each issue contains scientific research and authoritative review articles reporting on a variety of topics in food science pertaining to food safety and quality. The Journal is internationally recognized as the leading publication in the field of food microbiology with a readership exceeding 11,000 scientists from 70 countries. The Journal of Food Protection is indexed in Index Medicus, Current Contents, BIOSIS, PubMed, Medline, and many others.

    Print and online subscriptions are available to IAFP Members and institutional subscribers. IAFP Members with a subscription to JFP Online will have access to all available JFP and JMFT content. Online visitors who are not IAFP Members or journal subscribers will be charged on a pay-per-view basis. Membership and subscription information is available at
  • Information for Authors
  • Submit a Paper
  • Subscribe to this Title
  • Membership Information
  • Information for Advertisers
  • Ingenta Connect is not responsible for the content or availability of external websites

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Partial Open Access Content
Partial Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more