Shelf life and eating quality of beef from cattle of different breeds given diets differing in n-3 polyunsaturated fatty acid composition

Vatansever, L Kurt, E Enser, M Nute, GR Scollan, ND Wood, JD Richardson, RI

L. Vatansever et al., Shelf life and eating quality of beef from cattle of different breeds given diets differing in n-3 polyunsaturated fatty acid composition, ANIM SCI, 71, 2000, pp. 471-482

25

INGLESE

Article

Animal Sciences

ANIMAL SCIENCE

1357-7298 → ACNP

71

2000

3

471 - 482

ISI

1357-7298(200012)71:<471:SLAEQO>2.0.ZU;2-#

Two experiments were conducted with 32 Charolais cross steers (experiment 1 ) and 36 Holstein-Friesian and Welsh Black steers (experiment 2) to examine the effects of dietary n-3 polyunsaturated fatty acids (PUFA) and breed on meat quality Diets were comprised of grass silage and a concentrate (60: 4 0 on a dry-matter basis). Lipid in the concentrate provided 30 g/kg diet dr y matter derived from either linseed, fish oil or linseed/fish oil (experim ent I); and linseed or linseed/fish oil (experiment 2). These n-3 PUFA sour ces were compared with Megalac, a saturated fatty acid control, in both exp eriments. Diets were offered for 120 days (experiment 1) and 90 days (exper iment 2). Measurements of meat quality included fatty acid composition, lip id oxidation and colour during retail display (i.e. shelf life parameters) and eating quality assessed by a trained taste panel. The samples examined were sirloin (longissimus) steaks and minced beef burgers produced from the forequarter muscles infraspinatus, supraspinatus and triceps brachii. The fatty acid results showed that linseed increased the proportion of 18:3 n-3 (alpha -linolenic acid) in neutral lipid of the burgers and approximately doubled it in the phospholipid. Increased synthesis of 20 : 4 n-3 and 20: 5 n-3 also occurred, raising their levels in the phospholipid. Fish oil doub led the proportions of 20 :5 n-3 and 22 : 6 n-3, with the linseed/fish oil results intermediate between linseed and fish oil. The Welsh Blacks in expe riment 2 had higher proportions of 28:3 n-3 in neutral lipid and higher pro portions of 18 : 3 n-3, 20 :5 n-3 and 22 : 5 n-3 in phospholipid This showe d a clear genetic effect on fatty acid composition. The fish oil diet in ex periment I greatly increased lipid oxidation during retail display in both overwrapped loin steaks and burgers packed in a modified atmosphere. Values for lipid oxidation in the burgers were much higher than in the steaks due to the intimate mixing of phospholipid fatty acids and prooxidants. Lipid oxidation was also greater in the linseed/fish oil samples than controls in both experiments but was similar in linseed and controls. Colour oxidation also proceeded more rapidly in the fish oil samples in experiment 1: and t ended to be faster in the linseed/fish oil groups in both experiments. Eati ng quality was affected by diet in experiment 1 - the fish oil samples elic iting higher scores for 'fishy' and 'rancid' than controls and having lower 'overall liking' scores. Steaks From animals given the linseed diet (with high 18:3 n-3 proportions) had the highest 'overall liking' scores in exper iment I but the cattle given linseed for the shorter time in experiment 2 w ere not different from controls. Despite their different PUFA profile in mu scle, Welsh Blacks had similar eating quality scores to Holstein-Friesians which deposited move neutral lipid (marbling fat) in muscle.