Pre-scald brushing – removing solids, bacterial contamination

31-05-2017 | | |
Pre-scald brushing   removing solids, bacterial contamination. Photo: Meyn
Pre-scald brushing removing solids, bacterial contamination. Photo: Meyn

Live broilers contain micro-organisms as Campylobacter and Salmonella on their feathers and feet and once in the slaughterhouse may contaminate the carcasses during processing.

The results can be a final product which is contaminated with low levels of pathogenic bacteria. Interventions are needed in order to reduce contamination of carcasses, however, carcass treatment with chemicals or irradiation is not acceptable, other measures as logistic slaughter have shown a low effectiveness. Interventions should be applied at the start of processing, as micro-organisms can firmly attach to the skin within a few seconds and are difficult to remove.

Little is known about the effect of interventions applied before scalding on microbial concentrations on carcasses after scalding and the end of processing. Scalding directly follows bleeding and microbial counts are reduced due to temperature and washing effects. This reduction can be negatively affected by faecal matter entering the scald tank together with broiler carcasses. Faecal matter contributes to an increase in the dry matter content of scald water and a decrease in the pH value of this water. Adding chemicals to the scald water and maintaining the pH around 9, has not resulted in a significant reduction of micro-organisms on the carcasses after scalding. In addition the amount of dry matter, the protein content and the temperature of scalding water affect the reduction of micro-organisms in scald water. By reducing the faecal contamination on carcasses entering the scalding tank, not only the microbial concentration on carcasses can be reduced, also a reduction in pH level of scalding water can be prevented.

Recently a prototype mechanical cleaning for broiler chicken carcasses was developed, using a set of brushes to remove faecal material from broilers prior to scalding. It was investigated whether after using these brushers, in a stand-alone unit, a reduction in microbial concentrations was realised and whether the brushing affected the dry matter content and the pH of the scald water. Carcasses were sampled by the whole carcass rinsing method, rinse water samples were also used for determination of dry matter content and pH value. Statistical significant differences in microbial counts, dry matter content and pH values were estimated as a result of the treatment. More research is needed to measure these effects after in-line instalment of the brushers.

This research has been funded by Meyn.

Pacholewicz Len J-A- Lipman Arno Swart Arie H- Havelaar