EFFECT OF BREED AND ULTIMATE PH ON THE ODOR AND FLAVOR OF SHEEP MEAT

Coopworth and Merino lambs were slaughtered at 8 months after being grazed together on ryegrass/clover pasture from weaning. The flavour and odour intensities of the cooked lean (longissimus lumborum muscle) and odour intensity of subcutaneous fat were assessed by an analytical panel. Sheepmeat flavour in the lean was stronger (P < 0.01) in Coopworth and foreign flavour was stronger in Merino (P < 0.001). However, the mean pH of the meats also differed significantly (P < 0.001) (Coopworth, 5.77; Merino, 6.16), thereby confounding the effects of pH and breed. Panelists' comments pointed to a breed effect in subcutaneous fat odour, but means for sheepmeat and foreign odours in the fat were statistically identical. Meat toughness, assessed by the same panel, peaked around pH 6.0, irrespective of breed. In a parallel study of the Merino lambs and five Merino cross breeds, an in-house panel assessed acceptability rather than intensity of meat attributes. All crosses and the pure Merino produced meat that was acceptable (5 or more on a 1-9 hedonic scale) for aroma, flavour, tenderness, texture, and juiciness. There was a breed effect for tenderness (P < 0.05) however, with Merino being the most tender and the Texel x Merino being the least. When breed was disregarded, texture and tenderness were the best predictors of overall acceptability (r = 0.86, 0.80) and pH, which ranged between 5.41 and 7.12, was the poorest predictor (r = -0.14 to 0.12). The mean pH values of meat from the five cross breeds ranged between 5.93 and 6.08; i.e. lower than the mean pure-Merino pH and higher than the Coopworth pH. All animals were handled identically at slaughter. Thus, the Merino breed might be prone to the high pH condition which, in turn, would adversely affect bacteriological stability in chill storage. High pH meat might also affect meat odour and flavour. If Merino meat is destined for the chilled meat trade, particular care might be needed to ensure animals are not stressed.