Microbial immobilisation treatments of cattle hides - A novel approach to hide intervention strategy

Abstract

Cattle hide decontamination treatments have been recognized as an effective way to reduce microbial contamination of beef carcasses during slaughter and dressing in abattoirs. A range of related techniques - aimed at killing and/or removing pathogens on hides - have been considered in previously published studies. However, reported microbial reductions achievable were relatively limited: around 2-3 logs on decontaminated hides or about 1 log on resulting dressed carcasses. Consequently, to improve the effectiveness of hide treatments, a new approach - treatment to immobilize microbiota on cattle hide rather than to kill it - has been proposed. An insect-produced, natural, food-grade resin (Shellac) was evaluated as an on-hide microbiota-immobilizing agent in a laboratory models system using a sponge-swabbing microbiological sampling method. On hides spray-treated with a Shellac-in-ethanol solution, recoveries of general microbiota (total viable count of bacteria-TVC, Enterobacteriaceae counts and generic E. coli counts) were greatly reduced: up to 6.6 log10 CFU/cm2 reductions. The effects of the Shellac treatment were mainly due to immobilization of bacteria on hair by the resin, and to lesser extent due to bactericidal action of the ethanol. Furthermore, post-slaughter but pre-skinning treatment of hides with Shellac-in-ethanol solution, under practical conditions of small commercial abattoir operation, significantly reduced (up to 1.7 log) levels of general microbiota found on final beef carcasses. Overall, in both laboratory- and abattoir-based experiments, microbial reductions achievable by the Shellac-treatment of hides were superior - on both hides and beef - to those achievable by a control hide treatment using rinse-vacuum with sanitizer. Therefore, the Shellac treatment of hides can be considered as an effective alternative approach to hide decontamination strategies to improve beef safety.