ABSTRACT: γ-Oryzanol and α-tocopherol were added to beef patties as natural antioxidants. Beef patties containing 100 ppm γ-oryzanol had higher oxidative stability ( P <0.05) during storage at 4 °C than did beef patties with other antioxidants and without antioxidant. Thiobarbituric acid-reactive substances (TBARS) values, warmed over flavor (WOF) scores, C-7 oxidized cholesterol derivatives (OCDs), and concentrations of both hydroperoxide and hexanal in the cooked beef containing γ-oryzanol were significantly lower than those of other treatments ( P < 0.05). All variables had similar trends during the refrigerated storage. Significant correlations were found between TBARS and C-7 OCDs, TBARS and WOF, hydroperoxide and hexanal, and hexanal and WOF ( P < 0.05). 相似文献
Anaerobic adhesives polymerise rapidly, by a free radical mechanisms, when confined between two closely fitting metal surfaces to form tough solvent and heat resistant material. Anaerobic adhesives are typically based on methacrylate monomers and are predominantly used for the sealing and retaining of metallic objects. Transition metal ions on the substrate surface play a key role in the cure chemistry, catalytically decomposing hydroperoxides, such as cumene hydroperoxide, present in the adhesive to generate free radicals capable of initiating polymerisation. This study investigates the ability of lower and higher oxidation states of copper and iron to decompose cumene hydroperoxide, and also investigates the influence of saccharin, maleic acid and adhesive accelerators on this process. 相似文献
Decomposition of cumene hydroperoxide (CHP) was undertaken in a free radical chain reaction. The peroxyl group is very active and unstable, while the remainder of the molecule is inert. CHP reacted with various concentrations of dilute sodium hydroxide as a catalyst to cleave at ambient and decomposition temperature. The products were verified by GC/MS, and were quantitatively analyzed by chromatography. CHP cleaved heterolytic with NaOH at 250 degrees C, whose major product was dimethylphenyl carbinol (DMPC); however, the main products become acetophenone and alpha-methylstyrene by cleaved homolytic pathway. The catalytic concentrations of NaOH significantly affected the branch ratios of DMPC under decomposition. Based on the experimental results, a radical cleavage mechanism was proposed. To sum up, the reaction parameters, such as temperature, Lewis base, etc., could affect the incompatibilities and decomposition pathways for proper CHP cleavage process. In addition, exothermic onset temperatures (T0) and heat of decomposition (Delta Hd) of incompatible mixtures and CHP itself were studied by differential scanning calorimetry (DSC). Comparisons of T0, Delta Hd and peak power were assessed to corroborate the severity of thermal hazards. From the decay rate of CHP concentration, the reaction order was determined to be 0.5, and the Arrhenius parameters were measured as Ea=92.1 kJ/mol and frequency factor A=2.42 x 10(10)min(-1). 相似文献
Benzophosphole derivatives have attracted significant attention as promising organic optoelectronic materials. We have successfully developed a copper (2 mol%)/tert‐butyl hydroperoxide (2 equiv.) catalyst system for reaction of readily available secondary phosphine oxides and alkynes in acetonitrile at 60 °C under air, which provides a rapid access to a structurally diverse array of benzophosphole oxides in moderate to good yields within 30 min. The method can be easily used for a large‐scale preparation. Preliminary mechanistic studies revealed that the addition of a phosphoryl radical onto a triple bond followed by cyclization on the phenyl moiety of the secondary phosphine oxide might occur to form the benzophosphole oxide.
