The effect of preheating on the survival of L. monocytogenes in Richard's broth, which mimics the composition of Camembert cheese composition, was examined. Experiments were carried out to reproduce
contamination of cheese with environmental heat-stressed cells of L. monocytogenes surviving hot-cleaning procedures. Cells in mid-log phase were heated for 30 min at 56°C before being inoculated
into Richard's broth. The pHs and temperatures of Richard's broth were chosen to recreate the conditions of curd dripping (pH 5, 25°C), of the beginning of cheese ripening (pH 5, 12°C), and of the
beginning (pH 5, 4°C) and the end (pH 7, 4°C) of cheese storage. Immediately after heat treatment, the viability loss was especially high for strain 306715, which exhibited only 0.6% ± 0.2%
survival, compared with 22% ± 8.7% for strain EGD. The percentages of the surviving heated cells that were injured were 93% ± 8% for strain 306715 and 98% ± 3% for strain EGD. The destruction
of the surviving L. monocytogenes cells was accelerated when they encountered the pH and temperature conditions of Camembert cheese during manufacturing, ripening, and cold storage (pH 5 at 25, 12,
and 4°C, respectively). The multiplication of the surviving heated cells was retarded under favorable growth conditions similar to those of storage by the distributor and the consumer (pH 7 at 4 and
Document Type: Research Article
Association ASEPT, BP 2047, 53020 Laval cedex 9, France 2:
Institut National de la Recherche Agronomique, Pathologie Infectieuse et Immunologie, 37380 Nouzilly, France
Publication date: February 1, 2003
More about this publication?
IAFP members must first sign in on the right to access full text articles of JFP First published in 1937, the Journal of Food Protection®, 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 Members and Institutional subscribers. Online visitors who are not IAFP Members or journal subscribers will be charged on a pay-per-view basis. Information can be obtained by calling +1 800.369.6337; +1 515.276.3344; fax: +1 515.276.8655, E-mail: email@example.com or Web site: www.foodprotection.org