ARS | Publication request: Influence of Nacl Content and Cooling Rate on Outgrowth of Clostridium Perfringens Spores in Cooked Ham and Beef

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: June 12, 2002
Publication Date: August 15, 2002
Citation: ZAIKA, L.L. INFLUENCE OF NACL CONTENT AND COOLING RATE ON OUTGROWTH OF CLOSTRIDIUM PERFRINGENS SPORES IN COOKED HAM AND BEEF. MEETING ABSTRACT. 2002.poster PM39.

Technical Abstract: The ability of Clostridium perfringens to grow from spore inocula was studied during cooling of ham and beef. Sufficient NaCl was added to ground commercially obtained cooked ham to contain 2.4, 3.1, 3.6 and 4.1% (w/w) and to raw ground beef to contain 0, 1, 2, and 3% (w/w). The samples were inoculated with a three-strain mixture of C. perfringens spores to obtain about 3 log10 CFU/g. Portions, 5 g, of meat in bags were vacuum-packed and stored at -40oC. Samples were heated at 75oC for 20 min and subsequently cooled from 54.4oC to 7.2oC in 15, 18, or 21 h. C. perfringens was enumerated by plating on tryptose-sulfite-cycloserine agar and incubating anaerobically at 37oC for 48 h. Population densities in ham and beef increased with increasing cooling time, and NaCl exerted a strong inhibitory effect. In beef, while 3% NaCl completely arrested growth, pathogen population increased by > 2 and > 5 log10 CFU/g in 15 and 18 h, respectively, when the NaCl content was < 2%. C. perfringens did not grow during cooling in 15, 18 or 21 h in ham samples containing > 3.1% NaCl. Results suggest that 15 h cooling of cooked ham would yield an acceptable product (< 1 log10 CFU/g increase in C. perfringens population) when the NaCl concentration is > 2%.