Enriching M. sternomandibularis with alpha-tocopherol by dietary means does not protect against the lipid oxidation caused by high-pressure processing.
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abstract
We hypothesized that elevating the concentration of alpha-tocopherol in beef muscle tissue by dietary means would increase lipid stability following high-pressure processing. Beef M. sternomandibularis was obtained from cattle that had medium (4.92 microg/g) and high (7.30 microg/g) concentrations of alpha-tocopherol. Post-rigor, paired muscles samples were subjected to pressures of 0.1 (atmospheric), 200 or 800 MPa for 20 min at approximately 60 degrees C. Following high-pressure processing, measurements were made immediately (d 0) or on samples stored in the dark for 6 d at 4 degrees C (d 6). Intramuscular lipid was similar for each group (4.02% vs. 4.26%, respectively; P=0.78), but lipid from the medium alpha-tocopherol muscle was more saturated and less monounsaturated than muscle from the high alpha-tocopherol group. High-pressure processing at 800 MPa and 60 degrees C did not reduce the amount of alpha-tocopherol but significantly reduced the concentration of linoleic acid (18:2n-6) in muscle from both production groups of cattle. Thiobarbituric acid reactive substances increased linearly with treatment pressure only in d 6 samples (day x pressure interaction P=0.0001) and were higher overall (P=0.02) in the high alpha-tocopherol muscle than in the medium alpha-tocopherol muscle. At d 6, lipid peroxides were decreased (P=0.007) by high-pressure treatment and were higher (P<0.0001) in the high alpha-tocopherol group than in the medium alpha-tocopherol group. Therefore, muscle from the high alpha-tocopherol cattle in this study had a greater accumulation of lipid peroxides by d 6, making the muscle from those cattle more susceptible to oxidation.
