Submitted to: International Association of Milk Food and Environmental Sanitarians
Publication Type: Abstract Only
Publication Acceptance Date: January 16, 1996
Publication Date: N/A
Technical Abstract: Two experiments were performed to determine if immobilization of nisin in an edible gel was an effective delivery system for a bacteriocin to the carcass surface as well as into ground beef. In both experiments, post-rigor lean and adipose beef carcass tissues were inoculated with Brochothrix thermosphacta (BT), left untreated (U), or treated with 100 ug/ml nisin (N), calcium alginate (A), or 100 ug/ml nisin immobilized in a calcium alginate gel (AN). In the first experiment, samples were refrigerated after treatments and bacterial populations and nisin activity were determined at 0, 1, 2, and 7 days. In the second experiment, tissues were made into ground beef (15% adipose, 85% lean), refrigerated, and bacterial populations and nisin activity were determined at 0, 7, and 14 days. In both experiments, U, A, and N treatments of beef tissues did not suppress bacterial growth for the duration of the experiment. However, in experiment 1, bacterial populations treated with AN were suppressed to < 2.42 log CFU/cm**2 by day 7. In experiment 2, bacterial populations treated with AN were suppressed to < 1.3 log CFU/cm**2 at day 0; however, bacterial populations of AN grew to similar levels of U, A, and N (>7 log CFU/cm**2) by day 14. Bacteriocin titers taken from both experiments demonstrated that nisin activity was higher in AN versus N samples up to day 7. These studies alternatively indicate that nisin delivery in an edible gel is more antimicrobial than the addition of liquid nisin to surface tissue or ground beef.