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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Food Microbiology
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1485398

Inactivation Kinetics of Listeria monocytogenes and Salmonella enterica on Specialty Mushroom Garnishes Based on Ramen Soup Broth Temperature

Provisionally accepted
Joelle K Salazar Joelle K Salazar *Megan Fay Megan Fay Gregory Fleischman Gregory Fleischman Bashayer Khouja Bashayer Khouja Diana Sue Stewart Diana Sue Stewart David Thomas Ingram David Thomas Ingram
  • United States Food and Drug Administration, Silver Spring, United States

The final, formatted version of the article will be published soon.

    Recent listeriosis and salmonellosis outbreaks in the U.S. have been associated with consumption of specialty mushrooms, including enoki and wood ear. These mushrooms are commonly consumed in Asian dishes such as ramen noodle soup and are often used as raw garnishes. No current guidelines exist for the serving temperature of ramen broth in restaurants for safety. The objective of this study was to evaluate the inactivation of both Listeria monocytogenes and Salmonella enterica on enoki and wood ear mushrooms based on the ramen broth temperature.Fresh mushrooms were chopped into pieces, inoculated with four-strain cocktails of L. monocytogenes or S. enterica, dried at ambient conditions for 30 min, then placed into bowls.Ramen broth (i.e., pork bone broth, Tonkotsu) at initial temperatures of 60, 70, 80, 90, or 100°C was poured over the mushrooms, submerging them. The bowls were held at ambient conditions while the broth temperatures were monitored, and mushrooms were sampled at intervals up to 60 min. From the broth temperature profiles and the pathogen log reductions of each mushroom type, the non-isothermal log-linear model was used to obtain maximum inactivation rates. The maximum pathogen inactivation on both mushroom types occurred within the first 5 min, regardless of the initial broth temperature. Broth temperatures of 60 and 70°C resulted in reductions of only 1-3 log CFU/g (inactivation rates of 0.33 to 4.72 log CFU/g/min), while reductions of 4-5 log CFU/g (inactivation rates of 8.74 to 17.21 log CFU/g/min) were observed with 80°C broth. The use of 90 and 100°C broth resulted in higher reductions of >5 log CFU/g (inactivation rates of 8.56 to 28.08 log CFU/g/min). In all cases, surviving populations, often >2.4 log CFU/g, were observed after 60 min. The results from this study can assist in the development of guidelines on the safe serving temperature of ramen soup at restaurants.

    Keywords: Enoki mushrooms, Heat treatment, Listeria, Ramen, Salmonella, wood ear mushrooms

    Received: 23 Aug 2024; Accepted: 21 Nov 2024.

    Copyright: © 2024 Salazar, Fay, Fleischman, Khouja, Stewart and Ingram. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Joelle K Salazar, United States Food and Drug Administration, Silver Spring, United States

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.