Project Summary

Novel Uses of Natural Tannin Sources to Mitigate Risk of Escherichia coli O157:H7 and Other Food Pathogens Contamination of Beef through Integrated Pre- and Post-Harvest Strategies

Principle Investigator(s):
William E. Pinchak, Byeng R. Min, Robin Anderson, and Gordon E. Carstens
Texas Agricultural Experiment Station
Completion Date:
May 2006



The bovine gastrointestinal tract is a reservoir for E. coli O157:H7, Salmonella, and to a lesser extent, Campylobacter. In the United States, food borne microbial illness is a major cause of personal distress, preventable death, and avoidable financial loss. It is estimated that 6.5 to 33 million people become ill from pathogens in food every year, resulting in an estimated 9,000 deaths (FDA/FSIS, 2000) and financial lost at a cost exceeding $6.9 billion (ERS/USDA, 2003). Cross-contamination from the gastrointestinal tract to the animal or meat can occur in pre-harvest, post-harvest and fabrication phases of beef production. Post-harvest interventions developed to kill pathogens present on the carcass or equipment are not completely effective. Lacking are integrate systematic and preventive process control from the Farm to the Table to make all meat products as safe as possible. Consequently, development of integrated practical pre-harvest and post-harvest interventions are needed and inclusion of tannin-based strategies hold promise for incorporation in all phases of production utilizing natural compounds that are generally regarded as safe. 

Recently, Texas Agricultural Experimental Station, Vernon and USDA/ARS Food and Feed Safety Research Unit, College Station, TX scientists have discovered plant tannins extracts that reduced in vitro E. coli O157:H7 and Staphylococcus aureus and suppressed in vivo generic fecal E. coli populations. Preliminary research suggests when fed at low levels (<120 g/hd/day), tannins decreased fecal generic E. coli by one log scale and animal production may be increased by 15% in steers grazing winter wheat forage (60-d trial) (Table 1 and Min et al., 2005c). Additionally, we have found tannins that can reduce in vitro and in vivo growth and bio-film production of major rumen bacteria. 

The applications and uses of tannins compounds in the mitigation of food safety systems, to decrease food pathogens, increase rumen escape protein (Min et al., 2003) and improve production efficiency in grazing (Min et al., 2005c) and feedlot cattle (unpublished data) are new and unique to our research program. Moreover, a need exists to make any pre-harvest technology acceptable to cattle producers and feeders since they must maintain or improve feed efficiency, while improving food safety. Therefore, we propose the following research to obtain fundamental information on the mode of action of tannins in integrated food safety systems, that will yield a better understanding and knowledge base of the pathogenic bacterial control by sources of tannins interactions that affect food safety and beef production systems. 

The stated objectives for this work were: 

  • Determine the effectiveness of commercial tannins delivered as a feed supplement on generic fecal E. coli and E. coli O157:H7 shedding and animal average daily gain in
  • finishing feedlot cattle over 30, 60, 90, 120 and 150 day feeding periods and to quantify bacteriostatic and bactericidal capacity of these compounds.
  • Characterize the efficacy of tannin compounds applied pre-harvest on cattle in decreasing fecal pathogens (E. coli O157:H7, Salmonella, and Campylobacter) loads on cattle hides prior to the harvest phase.
  • Quantify the response of food pathogens (E. coli O157:H7, Salmonella, and Campylobacter) and associated bio-films to post-harvest carcass application of plant tannins to reduce pathogen transport to the fabrication phase. 

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