Inhibition of Listeria monocytogenes on Beef Tissue by Application of Organic Acids Immobilized in a Calcium Alginate Gel


  • We thank Dr. Donald Thayer of the USDA-ARS, ERRL, Philadelphia, PA for irradiation sterilization of the test meat samples, Ms. Jane Long and Ms. Carole Smith for technical support, and Ms. Marilyn Bierman for preparation of the manuscript.

  • Mention of a trade name, proprietary product or specific equipment is necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.


Organic acids added to calcium alginate gels and immobilized on lean beef tissue inoculated with Listeria monocytogenes (Lm) reduced the population significantly more than did acid treatment alone. Lactic acid (1.7% v/v) immobilized in alginate reduced counts by 1.3 log10 units vs 0.03 log unit decrease from the acid treatment alone. Acetic acid (2% v/v) reduced counts 1.5 and 0.25 log units, respectively. Over 7 days, Lm proliferated in samples without acid and/or alginate treatment. Differential counts on selective and non-selective agars indicated sublethal cellular injury occurred. Alginate coatings did not enhance acid inhibition on fat tissue. Immobilized agents may have potential for raw meat decontamination.