The triacylglycerol preparation of conjugated linoleic acid reduces lipid oxidation in irradiated, cooked ground beef patties.
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It is proposed that conjugated linoleic acid (CLA) would depress the lipid oxidation caused by irradiation of cooked, aerobically stored ground beef patties. The free fatty acid (FFA-CLA) and triacylglycerol (TAG-CLA) preparations of CLA were added at 0%, 1%, 2%, or 4% during the grinding process. Patties were irradiated at 1.5-2.0kGy and frozen at -20C. Subsequently, the patties were tempered to 4C, cooked to 70C and held at 4C for 7d. Enrichment of ground beef with CLA increased the cis-9,trans-11 and CLA trans-10,cis-12 CLA isomers in ground beef patties, even after cooking. Weight loss (P=0.03) and percentage fat (P=0.05) were higher in irradiated beef patties than in control patties. Irradiation decreased the concentration of -linolenic acid (18:3n-3) in the ground beef by over 60% (P=0.07), whereas thiobarbituric acid reactive substances (TBARS) values were higher (P=0.004) in irradiated beef patties than in control patties. The 1% concentration of added TAG-CLA reduced TBARS in irradiated ground beef patties, whereas 2% and 4% FFA-CLA depressed TBARS (CLA typepercentage interaction P=0.04). Irradiation increased the cardboard and painty aromatic attributes (P0.05), and FFA-CLA preparation increased the painty aromatic attribute and afterburn aftertaste, but these effects were not observed with the TAG-CLA preparation (CLA typetreatment interaction P<0.04). Adding 1% TAG-CLA to ground beef during grinding can reduce lipid oxidation in irradiated, cooked ground beef patties without the negative aftertastes associated with the FFA-CLA preparation.