Background 

Acidic Calcium Sulfate (ACS) plus organic acids have been reported to disable proton pumps in bacterial membranes and thus act as metabolic inhibitors. ε-Polylysine (EPL), on the other hand, is adsorbed into the cell surface of microorganisms as a result of its cationic properties and strips the outer membrane and distributes the cytoplasm. Lauric Arginate Ester (LAE), in comparison, prevents bacterial growth by altering the cell membrane structure of microorganisms. Thus, sequential application of two of these decontamination agents in combination might result in greater pathogen reductions than any single application of these agents on beef carcass surfaces due to their different modes of action. 

The stated objectives for this work were: 

1. Determine the effects of sequential application of EPL or LAE spray followed by an ACS spray as a multi-hurdle intervention for reducing Escherichia coli O157:H7 (EC) and Salmonella Typhimurium (ST) on the inoculated surface of beef rounds. 
2. Determine the effects of sequential application of an EPL or LAE spray followed by an ACS spray for reducing EC and ST on the inoculated surface of beef rounds stored for up to 6 days under refrigeration. 
3. Determine if sequential application of an EPL or LAE spray followed by an ACS spray were effective for reducing EC and ST on the inoculated surface of beef rounds and in ground beef manufactured from the treated rounds and held refrigerated for up to 4 days.

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