RESUMO
The effects of feeding composition on the photosensitized oxidation of lipids from beef meat, were evaluated during storage under commercial retail conditions. Feeding was enriched with linseed oil (LO), Dl-α tocopheryl acetate (vE) and conjugated linoleic acid (CLA) at different doses and provided for diverse periods, resulting in 7 diet groups (A-G). After slaughtering and 2 weeks of holding period, meat slices were packed in vessels with transparent shrink film and exposed to white fluorescent light for 8h at 8 °C. Total cholesterol oxidation products (COPs) level varied from 4.0 to 13.0 µg/g of lipids, which corresponded to 0.1-0.6% oxidized cholesterol. The lowest peroxide value (PV) was found in the diet added with vE and LO for 90 days. Light exposure only had a significant impact on thiobarbituric acid reactive substances (TBARs). In general, Dl-α tocopheryl acetate supplemented for 90 days improved the oxidative stability of beef meat stored under commercial retail conditions.
Assuntos
Dieta/veterinária , Gorduras na Dieta/análise , Conservação de Alimentos , Qualidade dos Alimentos , Armazenamento de Alimentos , Carne/análise , alfa-Tocoferol/administração & dosagem , Animais , Animais Endogâmicos , Bovinos , Colesterol/análogos & derivados , Colesterol/análise , Colesterol/química , Gorduras na Dieta/efeitos da radiação , Embalagem de Alimentos , Itália , Luz/efeitos adversos , Ácidos Linoleicos Conjugados/administração & dosagem , Óleo de Semente do Linho/administração & dosagem , Peróxidos Lipídicos/análise , Peróxidos Lipídicos/antagonistas & inibidores , Peróxidos Lipídicos/química , Masculino , Carne/economia , Carne/efeitos da radiação , Oxirredução , Processos Fotoquímicos , Análise de Componente Principal , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Substâncias Reativas com Ácido Tiobarbitúrico/químicaRESUMO
1H and 13C NMR spectroscopy was used to evaluate the degree of unsaturation and the cholesterol/cholesteryl ester ratio on the total lipid fractions obtained from human renal and cerebral tissues. The unsaturated/saturated fatty acid ratio was determined in the 13C NMR spectra from the ratio of the integrated areas of the resonances at 14.13 and 14.17 ppm assigned to the terminal methyl groups of saturated and unsaturated FA, respectively, and is validated by the traditional but time consuming gas-chromatographic analysis. Cholesteryl esters are easily discriminated in the total lipid fraction extracted from human tissues by means of the well-resolved component at 0.99 ppm (1H NMR spectra) of the resonance at about 1.00 ppm generally assigned to free cholesterol. The role of NMR spectroscopy in the study of lipidic biochemistry of human tissues is confirmed.
