Colour of subcutaneous adipose tissue and muscle of Irish beef carcasses destined for the Italian market.

Abstract

The purposes of this study were (i) to objectively measure the colour of carcass fat and muscle of heifers that had been previously selected, subjectively, for the Italian market and (ii) to define instrumental colour values which would describe the required fat colour for that market. On one day during each of 5 months (11 April, 13 June, 10 October, 10 November and 19 December) the ‘b’ (yellowness) value of carcass fat was measured at two positions (proximal pelvic limb area and the area between 9th rib and 4th lumbar vertebra) and the ‘L’ (lightness) and ‘a’ (redness) values of two muscles (M. longissimus dorsi (LD) and M. rhomboideus thoracis (RT)) were measured using a Minolta chromameter. Measurement date had a significant effect (P < 0.05) on ‘b’ values of fat at both positions, with carcasses displaying the most yellow fat on 13 June (P < 0.05). The LD was palest and most red on 11 April (P < 0.05) and the RT tended to be palest on 13 June but most red (P < 0.05) on 11 April. The ‘L’ value differed between muscles on 11 April (P < 0.01) and 19 December (P < 0.05) and the ‘a’ value differed between muscles on all dates except 13 June. The majority of carcasses on each date fell between muscle ‘L’ values of 31 and 35, regardless of muscle, and between muscle ‘a’ values of 18 and 22. It is concluded that application of a “cut-off” value to muscle colour would be futile but as 81% of accepted carcasses had fat ‘b’ values below 14.2, regardless of position, that this could be used as a threshold of acceptable yellowness.