Aging times and inclusion of unprotected or protected linseed oil on Nellore steers diet and its influence on cholesterol and lipid oxidation of the meat

Abstract Text:

The objective was to assess 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, over the cholesterol content and lipid oxidation 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 individual pens and adapted 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 of 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 6^th and 13^th ribs were removed and sampled as 2.54 cm steaks, individually vacuum packed and chilled to 2 °C for one, seven or 14 days. For cholesterol content, 10 g of fresh meat were used after each aging time, and the lipid oxidation was obtained by the method based on 2-thiobarbituric acid (TBARS), both using spectrophotometer with 538 nm. The results were submitted to analysis of variance using mixed models, considering a random block one, and a 3x3 factorial scheme. No interactions were observed, cholesterol content was not influenced by diet (P=0.5727) or by aging times (linear regression - P=0.5008, and quadratic - P=0.7493), showing lower levels than those considered normal for the Longissimus muscle (36.5 and 33.16 mg/100 g of muscle to diets and times aging, respectively), which is important because of its influence in preventing cardiovascular disease. Lipid oxidation was also not influenced by factors evaluated (P>0.005), and the average was 0.41 mg of malonaldehyde/kg of muscle. Add linseed oil on the diet of Nellore steers does not cause a loss in quality of meat for human consumption, using in natura or protected form.

Keywords: Longissimus, human health, TBARS