Assessment of in-plant decontamination of broiler carcasses by immersion in hot water and lactic acid in Norway

Abstract

This study investigated the effect of hot-water immersion, at different water temperatures and exposure times, on the microbiological loads on broiler carcasses. The combinations tested were 70 °C for 3 s, 80 °C for 3 s and 6 s, and 90 °C for 3 s. The separate effects of immersion in 5% lactic acid at 15 °C for 3 s and the on-line cold-water spray carousel on microbiological loads were also investigated. The study was conducted at a commercial broiler abattoir in Norway, where 110 carcasses were collected directly from the slaughter line after evisceration but before the cold-water carousel and brought to a separate room for immersion testing and microbiological sampling. Each carcass was assessed for skin injuries and discoloration post treatment, and sampling was by whole carcass rinse. Skin damage following hot-water treatment was not observed. A white coating developed on the skins of carcasses treated with 5% lactic acid after drying. For untreated carcasses, total plate count (TPC) mean was 4.9 log cfu/ml and E. coli mean was 4.0 log cfu/ml. Mean TPC were significantly lower (by 1.0–1.1 log cfu/ml) for carcasses immersed in hot water at 80 °C (3 and 6 s) and 90 °C. Only immersion in 80 °C for 6 s significantly reduced the E. coli mean (by 1.1 log cfu/ml). Immersion in 5% lactic acid reduced TPC by 4.0 log cfu/ml and E. coli by 3.9 log cfu/ml, with 9 of 10 samples below the detection level for E. coli. The cold-water carousel resulted in an insignificant reduction in TPC and E. coli levels. In conclusion, immersion for 6 s in 80 °C was the most effective hot-water treatment. Although lactic acid immersion is more effective, it is currently not permitted to use on broiler carcasses in Europe.