Bactericidal effects of Lactobacillus reuteri and allyl isothiocyanate on Escherichia coli O157:H7 in refrigerated ground beef.
Two naturally occurring antimicrobial agents were tested in packages of refrigerated ground beef for their ability to reduce the viability of Escherichia coli O157:H7 during storage. Allyl isothiocyanate (AITC) and Lactobacillus reuteri were tested separately and together for their action against a cocktail of five strains of E. coli O157:H7 in ground beef held at 4 degrees C for 25 days. Ground beef prepared from whole, raw inside round beef roasts was inoculated with low (3 log CFU/g) or high (6 log CFU/g) levels of the E. coli O157:H7 mixture. The beef was treated with AITC (about 1,300 ppm), L. reuteri, or both, along with 250 mM of glycerol per kg of meat at two levels (3 and 6 log CFU/g) and according to a design that yielded 8 controls plus 10 different treatments. Samples were analyzed for E. coli O157:H7 survivors, numbers of total bacteria, and lactic acid bacteria on days 0 to 25 at 5-day intervals. L. reuteri at both input levels with glycerol killed E. coli O157:H7 at both inoculated levels before day 20. AITC completely eliminated E. coli O157:H7 at the low-inoculum level (3 log CFU/g) and reduced viability >4.5 log CFU/g at the high-inoculum level (6 log CFU/g) by the end of the storage period. The combination of L. reuteri and AITC did not yield an additive effect against E. coli O157:H7 viability. L. reuteri in the presence of glycerol was highly effective against E. coli O157:H7 in ground beef during refrigerated storage (4 degrees C) in modified atmosphere packages. Sensory testing is planned to evaluate effects of treatments.
Muthukumarasamy
Parthiban
P
Department of Food Science, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
Han
Jung H
JH
Holley
Richard A
RA
D003080:Cold Temperature; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development*; D005516:Food Microbiology; D018857:Food Packaging; D005520:Food Preservatives / Q000378:metabolism / Q000494:pharmacology*; D005990:Glycerol / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D017879:Isothiocyanates / Q000378:metabolism / Q000494:pharmacology*; D007778:Lactobacillus / Q000502:physiology*; D008461:Meat Products / Q000382:microbiology*; D013997:Time Factors
D005520:Food Preservatives; D017879:Isothiocyanates; C004471:allyl isothiocyanate; D005990:Glycerol