The effect of ageing time was only significant for beef odour intensity in the BA and LI breeds. In both breeds, the values found at 35 days were the lowest and statistically diVerent to those observed at 1, 3 and 7 days. Nevertheless, these results could be partly explained by the muscle characteristics of the animals with higher muscle development. Thus, they have greater number of muscle cells, with a predominance of fast contracting white Wbres, which have faster degradation and higher ageing rates at short ageing times (Ouali, 1990), with a possible development of beef odours at these times. On the other hand, our results agree, in general, with those of Campo et al. (1999), who obtained the highest values of overall odour intensity in the four breed groups studied at 21 days of ageing but with a reduction of the natural flavour
perception. On the other hand, the HO and BS showed no signiWcant diVerences throughout the ageing time, but a similar tendency was observed. With regards to the liver odour intensity, there were no significant differences throughout ageing.