WARMED-OVER FLAVOR IN CHILL-STORED PRECOOKED PORK PATTIES IN RELATIONTO DIETARY RAPESEED OIL AND VITAMIN-E SUPPLEMENTATION

Lean pork; patties were produced from the longissimus nor si muscle of pigs fed either (1) basal feed containing 3% fat without vitamin E su pplementation (Control), (2) basal feed enriched with 6% rapeseed oil (canola) without vitamin E supplementation (RAP), or (3) basal feed en riched with 6% rapeseed oil and 200 mg vitamin E as all-rac-alpha-toco pheryl acetate/kg feed (RAP-E). Enrichment of the pig diet with rapese ed oil slightly increased the content of monounsaturated and polyunsat urated fatty acids and slightly reduced the amount of saturated fatty acids in the products, although the difference was not statistically s ignificant, The fat content in non-cooked patties was found to be simi lar for the three products, as was the level of secondary oxidation pr oducts determined as headspace hexanal and thiobarbituric acid reactiv e substances (TBARS), whereas the content of vitamin E as alpha-tocoph erol was found to be significantly different. alpha-tocopherol levels in non-cooked patties reflected dietary vitamin E levels and were: Con trol [2.33 mg alpha-tocopherol/kg dry matter (DM] < RAP (3.31 mg alpha -tocopherol/ kg DM) <RAP-E (6,26 mg alpha-tocopherol/kg DM). Heat trea tment of patties resulted in a 26-28% decrease in alpha-tocopherol con tent and degradation continued during chill storage (5 degrees C). The degradation of alpha-tocopherol was found to be proportional to the i nitial level, and the levels in pre-cooked patties were still related to dietary vitamin E levels after 4 days of chill storage. Development of warmed-over flavour in precooked patties during chill storage, as followed by determination of hexanal and TEARS and by descriptive sens ory analysis showed that (1) feeding pigs a level of 6% rapeseed oil i ncreases the susceptibility of precooked patties to lipid oxidation du ring chill storage, and (2) that supplementation of 200 mg vitamin E/k g feed effectively counteracts the effects of the rapeseed oil on lipi d oxidation.