Antimikrobni tretman kože goveda u cilju unapređenja mikrobiološke bezbednosti goveđeg mesa

Abstract

U radu je ispitan i razvijen novi pristup tretmanu kože goveda prirodnom smolom šelak, koja je dozvoljena za korišćenje u hrani, u cilju redukcije unakrsne mikrobiološke kontaminacije sa kože na goveđe meso. Mehanizam ovog tretmana je baziran na imobilizaciji mikroorganizama na dlaci tretirane kože i prevenciji njihovog fizičkog prenosa sa dlake na meso trupova tokom procesa obrade zaklanih goveda. U in vitro uslovima, tretman uzoraka vizuelno čiste i suve kože 23% rastvorom šelaka u etanolu je redukovao prenos sa kože na sunđere kojima je koža uzorkovana brisevima: ukupne mikroflore (TVC) za 6,6 log (>1000 puta više u odnosu na 2,9 log redukcije kod tretmana samo etanolom), generičke Escherichia coli za najmanje 2,9 i Enterobacteriaceae za najmanje 4,8 log. Ove redukcije sve tri grupe mikroorganizama su bile značajno više u odnosu na redukcije postignute tretmanom kože kombinacijom ispiranja sanitajzerom i vakumiranja. Značajno više redukcije prenosa TVC sa kože na sunđerske briseve su postignute korišćenjem viših koncentracija šelaka (23% i 30%) u odnosu na niže (4,8-16,7%) i u slučajevima kada je temperatura rastvora šelaka bila 20, 30 ili 40oC u odnosu na 50oC i 60oC. Takođe, tretman kože šelakom je značajno (3,7 puta) redukovao prevalencu E. coli O157 na prirodno kontaminiranoj, neinokulisanoj koži, kao i broj E. coli O157 na veštački inokulisanim kožama (redukcija od 2,1 log), u odnosu na odgovarajuće netretirane kontrole. U uslovima laboratorijskog modela direktnog kontakta kože i mesa, tretman kože (različitih kategorija čistoće) 23% rastvorom šelaka je značajno smanjio prenos mikroorganizama sa tretirane kože na sterilno goveđe meso: do 3,6 log cfu/cm2 redukcije ukupnog broja bakterija (TVC), do 2,5 log cfu/cm2 Enterobacteriaceae (EC) i do 1,7 log cfu/cm2 generičke E. coli (GEC). Redukcija prenosa TVC je bila značajno viša, a redukcije EC i GEC slične, u odnosu na redukcije nakon tretiranja kože kombinacijom ispiranja-vakumiranja sanitajzerom. U uslovima male komercijalne klanice sa nezadovoljavajućom procesnom praksom (klanje prljavih goveda i neadekvatna higijena procesa klanja i obrade), tretman koža zaklanih goveda 23% rastvorom šelaka je rezultirao značajnom mikrobnom redukcijom na mesu trupova goveda nakon skidanja kože: 1,7 log cfu/cm2 TVC, 1,4 log cfu/cm2 EC i 1,3 log cfu/cm2 GEC. Redukcija TVC na mesu trupova je bila značajno viša, a redukcije EC i GEC slične, u odnosu na redukcije nakon tretiranja kože ispiranjem-vakumiranjem sanitajzerom. Ova istraživanja su po prvi put pružila naučne dokaze da se tretman kože goveda u cilju imobilizacije mikroflore na dlaci može uspešno koristiti u cilju smanjenja kontaminacije mesa trupova tokom procesa skidanja kože, unapređenja finalnog mikrobiološkog statusa mesa i bezbednosti goveđeg mesa uopšte. Da bi se ostvario puni potencijal ovog novog tretmana u praksi, neophodna su dalja istraživanja u cilju njegove tehničke optimizacije u uslovima industrije mesa.

In this research, a new approach to cattle hide treatments, based on using a natural, food-grade resin, Shellac, to reduce microbial cross-contamination from the hides onto carcass meat, was developed and evaluated. The basis of this treatment is immobilisation of microorganisms on cattle hide’s hair and subsequent reduction of their transmissibility from the hair onto carcass meat during dressing of slaughtered cattle. Under in vitro conditions, treatment of samples of visually clean and dry hides with 23% Shellac-in-ethanol solution reduced sponge-swabbing recoveries of general microflora (TVC) by a factor of 6.6 logs (>1000-fold greater than the 2.9 log reduction observed by ethanol alone), and of generic E. coli (GEC) and Enterobacteriaceae (EC) by factors of at least 2.9 and 4.8 logs, respectively. The reductions of these three groups of microorganisms were superior to those achieved by a sanitizer rinse-vacuum hide treatment. Significantly greater reductions of TVC recoveries from hides were achieved when using higher Shellac concentrations (23.0% and 30.0% rather than 4.8-16.7%) and when Shellac solution temperatures were 20-40°C rather than 50-60°C. Furthermore, the Shellac-based treatment also markedly reduced the E. coli O157 prevalence (3.7-fold reduction) on natural, uninoculated hides, as well as the counts of E. coli O157 on artificially inoculated hides (2.1 log reduction) when compared to corresponding untreated controls. Under the conditions of a hide-to-meat direct contact laboratory-based model, treatment of hides (of varying visual cleanliness) with the 23% Shellac solution produced significant reductions of microbial transfer from treated hide onto sterile beef: up to 3.6 log10 CFU/cm2 of TVC, up to 2.5 log10 CFU/cm2 of EC and up to 1.7 log10 CFU/cm2 of GEC. TVC reductions of microbial transfer from treated hide onto beef achieved by the Shellac hide treatment were superior to those achieved by the comparative sanitizer rinse-vacuum hide treatment, but reductions of EC and GEC did not differ between the two hide treatments. In a small commercial abattoir with unsatisfactory process practices (slaughtering dirty cattle, inadequate process hygiene), treatment of hides with Shellac produced significant microbial reductions on skinned beef carcasses: 1.7 log10 CFU/cm2, 1.4 log10 CFU/cm2 and 1.3 log10 CFU/cm2 of TVC, EC and GEC, respectively. TVC reductions on skinned beef carcasses achieved by the Shellac hide treatment were superior to those achieved by the comparative sanitizer rinse-vacuum hide treatment, but reductions of EC and GEC did not differ significantly between the two hide treatments. These investigations produced the first scientific evidence that treatment of cattle hides with aim of immobilising microflora on the hair can be very successfully used to reduce carcass meat contamination during the skinning operation, thus improving the microbiological status of the final beef carcasses as well as the beef safety in general. To achieve the full potential of this new treatment in practice, further research aimed at its further technical optimization under real-life meat industry conditions is necessary.