Antimicrobial coatings inhibit S. enterica, E. coli O157:H7 on roasted turkey.

Antimicrobial-containing edible films and coatings have received attention as a new way to control the post-processing contamination of foods that contain Salmonella and E. coli O157:H7. These films have advantages over the direct application of antibacterial agents because films and coatings can be designed to slow antimicrobial diffusion from the surface of the food into the product.

Scientists at the University of California wanted to evaluate the initial antimicrobial effects of whey protein isolate (WPI) coatings incorporating lactoperoxidase (LPOS) against Salmonella or E. coli O157:H7 inoculated onto roasted turkey. They studied the effect of LPOS WPI coatings on the growth of Salmonella or E. coli O157:H7 on the turkey during storage. They compared the antimicrobial activities of the LPOS-incorporated coatings with the direct spreading of a LPOS solution. Their efforts indicate that LPOS WPI systems show potential for inhibiting microorganisms already present on ready-to-eat meat products, as well as for controlling microbial growth from contamination after the product is coated.

In their experiments, the researchers examined the initial antimicrobial effects of the LPOS WPI coatings using various inoculation levels and LPOS concentrations. They applied coating solutions to the surface of roasted turkey before and after inoculating it with five-strain cocktails of S. enterica or E. coli O157:H7.

The investigators conducted a storage study with the inoculated turkey for 42 days at 4 C and 10 C. Turkey samples for the study were inoculated before or after an LPOS WPI coating or LPOS solution was applied. LPOS WPI coatings containing 5% and 3% LPOS caused initial 2-log CFU per g reductions of Salmonella or E. coli O157:H7, respectively. This effect was observed whether the turkey was inoculated before or after being coated.

Populations of Salmonella and E. coli O157:H7 continued to be inhibited over the study's 42-day storage period. The bacteria were more effectively inhibited when researchers used the LPOS WPI coating, as compared with the LPOS solution.

Further information. Linda Harris, Department of Food Science and Technology, University of California at Davis, 1 Shields Ave., Davis, CA 95616; phone: [phone]; fax: [phone]; email: [e-mail].