Spoilage and Safety Characteristics of Ground Beef Treated with Lactic Acid Bacteria
Abstract:Lactic acid bacteria (LAB) can decrease numbers of Escherichia coli O157:H7 and Salmonella in ground beef during storage. Two dose-titration studies were conducted in ground beef to determine dose levels of LAB needed to inhibit the pathogens. A second study evaluated whether LAB masked changes typically associated with the spoilage of ground beef displayed under refrigerated (0°C) or abusive (10°C) temperatures packaged in both traditional overwrap (TOP) and modified atmosphere packaging (MAP; 80% O2–20% CO2). Microbial analyses were conducted to determine spoilage endpoints and pathogen reduction. In the dose-titration study, Salmonella was reduced by 3 log cycles at all doses (106, 107, and 108 LAB per g) after 3 days of storage and was eliminated after 5 days of storage. E. coli O157:H7 was reduced by 2 log cycles at all dosages after 3 days of storage and by 3 log cycles after 5 days of storage. In the spoilage studies, as expected, total aerobic plate counts and LAB populations in LAB-inoculated samples were higher than the controls initially, but the counts were similar near the end of the study. While total spoilage bacteria generally increased over time, very few differences existed between treatments stored at 0°C and 10°C in coliforms, Brochothrix thermosphacta, yeasts and molds, and Pseudomonas spp. counts for both the TOP and MAP samples. We conclude that LAB could potentially be added to ground beef in TOP and MAP as a processing intervention for E. coli O157:H7 and Salmonella without masking microbial spoilage characteristics.
Document Type: Research Article
Affiliations: 1: International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Box 42141, Lubbock, Texas 79409-2141, USA 2: International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Box 42141, Lubbock, Texas 79409-2141, USA, Alberta Agriculture and Food, Lethbridge, Alberta, Canada T1J 4V6 3: International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Box 42141, Lubbock, Texas 79409-2141, USA;, Email: Mindy.Brashears@ttu.edu
Publication date: November 1, 2009
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