Cattle lot fed for the Japanese market produce carcases of high value and thus downgrading based on meat quality represents a significant cost. The Meat Standards Australia guidelines for the rate of pH fall specify that carcases must not reach pH 6.0 before their temperature reaches 35°C, however limited experimental data suggests this is a common occurrence in heavy carcases produced for the Japanese market. Therefore a study was conducted to confirm this occurrence and to determine the impact of season on the incidence of fast pH fall. 811 carcases were examined from cattle fed for ~150 days, 411 in April and 400 in July. Initial pH (pHi) and temperature were measured on all carcases and then a sub-set of samples (200/season) were measured for traits such as colour, drip loss and protein solubility. pHi was measured on core muscle samples taken from the loin muscle between the 5th/6th ribs prior to entering the chiller. The pH at 35°C was predicted for a subset of 41 carcases based on data collected at the MSA site at the lumbarsacral junction using non linear regression. There was a significant relationship (P < 0.05) between pH at 35°C at the MSA site and the temperature at the sampling site at the 5th/6th rib used for determination of pHi. A large proportion of the carcases were outside the MSA pH/temperature window in both autumn (86%) and winter (95%). Season was found to have a significant effect on pH at 35°C (P < 0.001) and ultimate pH (P < 0.001) with higher values in the autumn and winter respectively. A high incidence of carcases exhibiting a fast pH decline at high temperatures was found, irrespective of season and the significance of this finding is discussed.
Proceedings of the New Zealand Society of Animal Production, Volume 67, Wanaka, 436-440, 2007
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