## 3 Results  
Color parameters L *, a *, b *, and C * changed during 60 min blooming. In the LL muscle, L * values ranged from 35.5 to 37.1, from 36.71 to 38.3, and from 37.1 to 38.2, whereas in the SM muscle, from 33.48 to 34.59, from 34.3 to 35.9, and from 34.5 to 36.8 on days 1, 9, and 14 of ageing, respectively. Blooming contributed to an increase in the values of a * in LL and SM muscles at each ageing time. In the LL muscle, the values of a * increased from 14.53 to 16.68, from 14.99 to 19.1, and from 16.07 to 20.16, and the parameter stabilized after 10, 15, and 25 min on days 1, 9, and 14 of ageing, respectively. In the SM muscle, the values of a * increased from 14.96 to 18.21, from 16.92 to 21.70, and from 17.0 to 21.56, and the parameter stabilized after 10, 30, and 10 min on days 1, 9, and 14 of ageing, respectively. Changes in the values of b * were also noted during 60 min blooming. In the LL muscle, the values of b * increased from 10.76 to 12.68, from 12.16 to 15.30, and from 13.02 to 16.09, and the parameter stabilized after 30, 20, and 20 min on days 1, 9, and 14 of ageing, respectively. In the SM muscle, the values of b * increased from 11.29 to 13.96, from 13.92 to 17.35, and from 13.3 to 16.7, and the parameter stabilized after 10, 25, and 10 min in meat aged for 1, 9, and 14 days, respectively. Changes in chroma, which defines color intensity (higher values indicate a more vivid color), followed a similar trend to changes in parameter a *. In the LL muscle, chroma increased from 18.09 to 20.68, from 19.31 to 24.5, and from 20.69 to 25.80, and it stabilized after 15, 20, and 25 min of blooming. In the SM muscle, chroma increased from 18.76 to 22.9, from 21.92 to 27.6, and from 21.6 to 27.2, and it stabilized after 10, 25, and 20 min on days 1, 9, and 14 of ageing, respectively. Differences in the values of hue angle during blooming were noted in both muscles only on day 1 of ageing when they increased from 36.0 to 38.2 in the LL muscle, and from 36.2 to 37.7 in the SM muscle. However, on subsequent sampling dates, no changes in the values of hue angle were observed during blooming in either of the studied muscles, due to changes that occurred in meat during ageing. The results of this study indicate that the time needed for the stabilization of individual color parameters varied, therefore, it was difficult to determine the optimal blooming time unambiguously. Thus, an attempt was made to use \(\Delta\)E for this purpose (Table 1). The color differences expressed as \(\Delta\)E\({}_{\rm xy}\) point to the relevance of the first 10 min in the intensity of blooming in the SM muscle. On days 1 and 14 of ageing, during the first 10 min of blooming, the color difference could have been seen even by an inexperienced observer, because \(\Delta\)E\({}_{\rm xy}\) exceeded 2 [26]. After 10 min blooming in samples aged for 1 and 14 days and after 5 min blooming in samples aged for 9 days, in blooming intervals, the changes that cause color differences between measurements were smaller and could have been distinguished by an experienced observer (\(\Delta\)E\({}_{\rm xy}\)\(<\) 2). In the LL muscle, the highest values of \(\Delta\)E\({}_{\rm xy}\) were also noted during the first 10 min of blooming, however, they were below 2, which indicates that color changes could have been distinguished only by an experienced observer. The color difference \(\Delta\)E\({}_{0}\) increased in both studied muscles during blooming regardless of ageing time. In the LL muscle, color stabilized after 15 min on day 1 of ageing and after 20 min on day 9 of ageing, and the observer could have seen an evident difference in color compared with the color of freshly cut beef (2 \(<\)\(\Delta\)E \(<\) 5). On day 14, color stabilized after 25 min and the observer could have an impression of two distinct colors (\(\Delta\)E \(>\) 5). In the SM muscle, the blooming process proceeded similarly to the LL muscle.