100B-15 |
Use of allyl isothiocyanate to reduce Escherichia coli O157:H7 in packaged ground beef patties |
D. NADARAJAH, J. H. Han, and R. A. Holley. Department of Food Science, University of Manitoba, 250 Ellis Building, Winnipeg, MB R3T 2N2, Canada Escherichia coli O157:H7, is a pathogen often found in ground beef, has severe consequences for the young, elderly and immuno-compromised because it produces toxin. One possible way to kill E.coli in ground beef is to introduce a volatile antimicrobial. Such an antimicrobial evaporates after the package is opened and during cooking, leaving no residue. The objective of the study was to eliminate E. coli O157:H7 in packaged ground beef through the incorporation of allyl isothiocyanate (AIT), a naturally occurring volatile compound found in horseradish. The experimental design was to inoculate a five strain E. coli O157:H7 cocktail (inoculums of approximately 103 cfu/g and 106 cfu/g) into ground beef patties (20% meat fat). AIT in corn oil (7:3 volume ratio) was added to a piece of filter paper, which was placed on top of a ground beef patty (100g) prior to gas flushing (100% N2) in a plastic bag (Nylon/EVOH/PE). The sealed plastic bags were stored at 4, 10 and –18oC for 7, 21 and 35 days, respectively. Following storage, the AIT levels in the package headspace were determined by gas chromatography. Total plate count was determined using trypticase soy agar while E. coli O157:H7 were determined on MacConkey Sorbitol agar. Results indicated that the numbers of total natural microflora in ground beef patties were reduced by approximately one log10 cfu/g at all three temperatures and periods of storage. With an initial population of 106 cfu/g, E. coli was reduced by 4 log10 when incubated at 4oC over 21 days; however, at 10oC over 7 days the reduction was approximately 0.5 log10. The results indicated that in ground beef AIT from horseradish effectively inhibited both pathogenic E. coli O157:H7 and the natural microflora, especially at normal refrigeration.
Session 100B, Food Packaging
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