THE EFFECT OF DIETARY VITAMIN-E SUPPLEMENTATION ON THE QUALITY OF FRESH AND FROZEN LAMB MEAT

The effect of dietary alpha-tocopheryl acetate supplementation on the uptake of alpha-tocopherol in ewe plasma, lamb plasma, milk, organs an d muscles was investigated. The oxidative stability and colour in fres h M. longissimus dorsi and frozen M. longissimus dorsi, M. psoas major and M. gluteus medius were also investigated. Ewes (n = 12) were sele cted and scanned to assess pregnancy, They were divided into two group s (n = 6). The control group was fed a diet containing 20 mg alpha-toc opheryl acetate/kg feed/day and the supplemented group fed a diet cont aining 1000 mg alpha-tocopheryl acetate/kg feed/day, for 9 weeks ante- parturition and 3 weeks post-parturition. The lambs were weaned at 3 w eeks and fed supplemented or basal feed for 10 weeks before slaughter. Plasma alpha-tocopherol increased significantly (p < 0.01) in ewes in the 9 weeks ante-parturition, and lamb plasma taken just before slaug hter was significantly (p < 0.01) higher for the supplemented group th an the basal group, following 13 weeks of supplementation. Milk alpha- tocopherol levels were significantly (p < 0.01) higher from ewes fed t he supplemented diet at parturition and for the three weeks of supplem entation post-parturition (p < 0.05). Supplementation increased the al pha-tocopherol levels in all tissues sampled. The alpha-tocopherol con centrations in M. longissimus dorsi and M. psoas major were also deter mined after frozen storage at -20 degrees C for 34 weeks. Frozen stora ge resulted in a significant (p < 0.01) reduction in mean alpha-tocoph erol levels for M. longissimus dorsi but not M. psoas major. Dietary s upplementation with alpha-tocopheryl acetate significantly (p < 0.05) increased the oxidative stability of lamb muscle. Surface colour (Hunt er L, a, b) was found to be negatively correlated with metmyoglobin co ntent. Supplementation reduced surface discolouration in refrigerated display under fluorescent light over a 6-7 day storage period. The eff ect It as more pronounced in frozen displayed muscles than in freshly displayed samples. Copyright (C) 1996 Elsevier Science Ltd.