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United States Department of Agriculture

Agricultural Research Service

Title: Monitoring Beef Carcass Surface Microbial Contamination with a Luminescence-Based Bacterial Phosphatase Assay

Authors
item Kang, Dong Hyun
item Siragusa, Gregory

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 30, 2001
Publication Date: N/A

Interpretive Summary: Total bacterial plate counts are strongly related to biotype I Escherichia coli. To monitor bacterial contamination on beef carcasses in a processing plant requires a very rapid test. With conventional methods, this requires about 24 to 48 hours before a result is obtained, a timeframe in which most beef carcasses are finished being processed and are ready for transportation or further processing. Therefore, a simple and rapid method to estimate the total bacterial plate count has the potential to monitor beef carcass surfaces to determine their degree of contamination and whether any deviations in the processing line are occurring. We evaluated the potential of a commercially available microbial phosphatase test for assessing the level of microbial contamination of beef carcasses. The microbial phosphatase assay was found to be a good method to estimate total bacterial plate counts in approximately 20 minutes vs the 24 to 48 hours for conventional culture methods. Food processors or manufacturers can use this rapid assay to easily estimate total bacterial counts on carcasses for monitoring processing steps so that potential carcass contamination with harmful bacteria is minimized.

Technical Abstract: A commercially available microbial phosphatase test kit (FCI; Fast Contamination Indicator) was evaluated as a rapid method for estimating microbial contamination levels on beef carcass tissues. A set of actual beef carcass surface samples (n = 70) was assayed using the assay as a means to rapidly (10 min) monitor carcass microbial contamination. A regression equation was developed in experiment one and tested on an independent population. There was agreement between this assay and conventional plating method for total aerobic mesophilic bacteria (r = 0.93). The predicted total mesophilic bacteria generated from the fitted regression line (predicted log10 CFU/cm**2= 0.7505 x log10 FCI microbial phosphatase test values + 0.6726) showed a high correlation with actual aerobic mesophilic total counts (r = 0.88). The FCI test offers a simple and rapid method to estimate microbial contamination levels on beef carcass tissues for monitoring microbial levels of beef carcasses.

Last Modified: 8/22/2014
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