Inhibition of Listeria monocytogenes on Pork Tissue by Immobilized Nisin

TONY J. FANG* AND CYI-CHEUN LIN

Graduate Institute of Food Science National Chung Hsing University Taichung, Taiwan, R.O.C.

ABSTRACT

   Nisin was immobilized in 1% calcium alginate gels to test their ability to inhibit Listeria monocytogenes growth and their stability on cooked pork. Nisin added to calcium alginate gels and immobilized on cooked pork tenderloins inoculated with L. monocytogenes reduced the population more than did free nisin treatment alone. Nisin (104 IU/ml) immobilized in alginate reduced counts by 1.74 log10 units vs. 0.53 log units decrease from the free nisin treatment alone after 14 days at 4 C. Immobilized nisin at 5 x 103 IU/ml reduced 1.14 log units of L. monocytogenes compared to 0.49 log units with samples treated with free nisin at 4 C after 14 days of incubation. The stability of nisin on cooked pork can be improved by alginate immobilization treatment which suggests this technique may have potential for meat decontamination.

Key words: Nisin, immobilization, Listeria monocytogenes, calcium alginate gels