Quantifying the rate of pH and temperature decline in lamb carcasses at three abattoirs in New South Wales

Abstract

The aim of this work was to benchmark the rate of pH and temperature decline in lamb carcasses (particularly the temperature at pH 6.0) at 3 commercial abattoirs across New South Wales. In total, 1197 carcasses were monitored over 13 months for pH and temperature decline. The lambs were sourced from a variety of regions, either direct from the paddock or from sale yards. Carcass weight was not significantly (P>0.05) different between abattoirs or seasons. There was a significant (P<0.05) interaction between abattoir and season for carcass fat depth at the 12th rib (GR) when adjusted to the same hot carcass weight, such that as carcass weight increased so did GR with changes in the relationship between seasons and abattoirs. The predicted pH at 3 h was significantly different between abattoirs, with abattoirs A and B having a significantly (P<0.05) higher pH than abattoir C. All abattoirs were different (P<0.05) for predicted temperature at 3 h, with abattoir A having the lowest and C having the highest temperature. Predicted pH at both 25 and 18°C were significantly different (P<0.05) between abattoirs, with abattoir C having the lowest and abattoir A having the highest pH at both temperatures. Abattoir A and B were not different for predicted temperature at pH 6.0, but abattoir C had a significantly higher temperature (P<0.05). Over all abattoirs only 18.8% of sampled carcasses complied with the recommended pH–temperature window of 18–25°C at pH 6.0. Of the carcasses sampled, 79.4% had a slow rate of pH decline and did not reach the onset of rigor (pH 6.0) by 18°C.