Reduction potential of steam vacuum and high-pressure water treatment on microbes during beef meat processing

In order to assess the reduction potential of steam vacuum treatment (SVT) and high-pressure water treatment (HPWT) to reduce microbial contamination during beef processing, ten randomly selected carcass halves and effluents were evaluated using microbiological reference methods and quantitative real-time PCR (qPCR). While SVT was applied after evisceration, HPWT was applied prior to carcass storage in a cooling room. The SVT showed no statistically significant reduction of aerobic mesophilic counts (AMC) or Enterobacteriaceae counts, although Pseudomonadaceae counts were slightly reduced on the surface of the carcasses. In contrast, HPWT caused a significant increase in the mean AMC and Pseudomonadaceae counts by 0.80 (5.3-fold increase) and 0.77 (5.9-fold increase) log(10) CFU/cm(2), respectively. As for total bacterial cell equivalents (BCE) using the 16s rRNA gene, the SVT caused a significant reduction of 0.70 log(10) BCE/cm(2) (0.8-fold decrease), whereas the HPWT caused a significant increase of 0.19 log(10) BCE/cm(2) (0.6-fold increase). When targeting C. jejuni, SVT appeared to have no impact on the C. jejuni cell equivalents (CJE), but there was a slight increase of 0.22 log(10) CJE/cm(2) (0.7-fold) observed with the use of HPWT. Overall, short exposure (10 s) to the HPWT had no effect in reducing contamination and rather posed a risk of introducing water- or airborne contaminants. In principle, SVT may be useful in reducing microbial contamination for the carcass site tested, but the effect should be interpreted as a part of the entire Hazard Analysis and Critical Control Point (HACCP) plan. Furthermore, we suggest the continued use of a combination of culture-based and culture-independent molecular techniques to get a more complete picture of the efficacy of specific beef carcass decontamination techniques.