The effect of pH decline rate on the meat and eating quality of beef carcasses

Abstract

An experiment was undertaken to examine the effect of rapid pH fall at a high muscle temperature on meat and eating quality of two beef cuts (striploin and cube roll). From 115 beef steer carcasses of which the right side of each carcass was subjected to electrical stimulation, 25 carcasses which exhibited the largest difference in the rate of pH fall in the M. longissimus between sides were selected for subsequent sampling. All of the stimulated sides missed the ‘ideal’ pH/temperature window (defined as temperature at pH 6 in the M. longissimus <35°C and >12°C) at the upper end, as did several of the non-stimulated sides. The mean temperature at pH 6 for stimulated sides from modelling was 40.9 versus 33.3°C for non-stimulated sides. Despite the significant effect of stimulation on pH decline there was no statistically significant impact on shear force or sensory traits of the M. longissimus, but there was a significant effect of aging on these traits. There was no effect of stimulation or pH decline on drip loss of the striploin. After 14 days of aging there was no effect of stimulation or ultimate pH on striploin purge, but there was a significant effect of pH decline. This was not, however, evident for purge of the cube roll aged for either 4 or 42 days. The redness of the cube rolls as reflected by a* values declined with days of display, with the decline more rapid for samples aged for 42 days compared with those aged for 4 days. For meat aged and displayed identically, the a* values were on average significantly lower for meat from non-stimulated carcasses, but apart from aging there was no effect on the wavelength ratio 630/580 nm, an indicator of the formation of metmyoglobin. There was also evidence that a rapid decline in pH increased the onset of lipid oxidation.