1267
Effect of aging times and inclusion of unprotected or protected linseed oil on the diet of Nellore steers over the color of Longissimus
The objective was to evaluate the effects of aging time and the inclusion of unprotected or protected linseed oil from rumen degradation on the diet of 21 Nellore steers, finished at feedlot in individual pens, and their influence over the color aspects of Longissimus muscle. At the beginning of the experiment, animals had 18 months of age and 397.74 ± 14.07 kg of BW and they were kept in adaptation during 21 days. The diets were composed by 40% corn silage and with no oil addition (73% TDN and 2.9% EE), with in natura linseed oil or with protected linseed oil (76% TDN and 6.1% EE). After 105 days at feedlot, the animals were slaughtered with 522.72 ± 27.99 kg of BW and carcasses were chilled for 24 hours. After this period, a section of the Longissimus between 6th and 13th ribs was removed and separated in 2.54 cm steaks, which were individually vacuum packed and chilled to 2 °C for one, seven or 14 days. After this processing, in different points of these steaks, we cut a cross-section of muscle, for exposure of myoglobin to oxygen for 30 minutes. Then, a colorimeter was used to determine the color of the meat, by evaluating the lightness (L*), 0 = black and 100 = white; redness (a*); and yellowness (b*). The results were submitted to analysis of variance using mixed models, considering a random block one, and a 3 x 3 factorial scheme. No interactions were observed between diets and aging times (P>0.05). For L* (40.84) and b* (14.85), no difference among treatments were found (P=0.4145 and P=0.0703, respectively), and the aging time showed a quadratic effect on both characteristics (P=0.0002 and P<0.0001). The values of a* (16.49) were not affected by diets (P=0.3116) and aging times (linear regression - P=0.9565; quadratic - P=0.5068). Protected or unprotected linseed oil can be used on Nellore steers diet without changing aspects of meat color.
Keywords: cattle, luminosity, meat