The effectiveness of the existing theoretical methods used in prediction of antioxidant activity, including structure-activity
relationships (SAR) and theoretical index, were evaluated. In most cases, it was found that the theoretical predictions were
consistent with the experimental data. Although only one mechanism, free radical scavenging, was considered in the theories,
the methods were valuable in predicting the activity of antioxidants to protect lipid oxidation. 相似文献
A novel ternary hybrid of thermoplastic polyurethane/hindered phenol/hindered amine was designed and prepared. Selected hindered phenols and hindered amines were settled down, respectively, in the soft and hard phases of TPU with molecular‐level dispersion. As a result, the ternary hybrid showed a prominent enhancement in the tan δ peak value and distinct broadening of the glass transition region, due to the formation of strong interactions (hydrogen bonding) between segment and small polar molecules occurred in each phase of TPU, which demonstrated the promising future as high‐performance damping material of this ternary hybrid.
Phenolic compounds are of fundamental importance to the shelf life of virgin olive oils because of their antioxidative properties.
In this paper, the evolution of simple and complex olive oil phenols during 18 mon of storage is studied by high-performance
liquid chromatography (HPLC) analysis. The olive oils under examination were from various olive cultivars, harvested in two
sectors in the same region at different stages of ripeness. The findings indicate that it is not the variety but rather the
ripeness of the olives and the soil and climate that influence the phenol composition of virgin olive oil. In addition, a
positive correlation was found between the age of the oils and the tyrosol to total phenols ratio. Lastly, gas chromatography-mass
spectrometry analysis confirmed that the unidentified peaks detected by HPLC were of a phenolic nature. 相似文献
Eight separate solvent systems were used with groats and hulls of several lines of oats to determine which system resulted
in the most effective, rapid extraction of antioxidants. Antioxidant activity at room temperature was estimated by using thin-layer
chromatography (TLC) along with a β-carotene spray. The greatest antioxidant activities were obtained with methanolic antioxidant
extracts derived from Noble and Ogle oats and hulls. These extracts were added to soybean oil (SBO) and their effectiveness
was compared with that of butylated hydroxytoluene (BHT), tertiary butyl hydroquinone (TBHQ) and a control (no additives)
at 32°C, 60°C and 180°C. A petroleum ether extract of Noble oats also was tested in SBO at 180°C. Peroxide values (PV) for
oils with added antioxidants during storage at 32°C and 60°C showed that the Ogle oat extract was more effective than the
other oat and hull extracts or the control. There were no significant differences in effectiveness among the extracts and
the control at 60°C. At 180°C, the stability of each oil was determined by measuring conjugated dienoic acid values (CD) and
the relative amounts of the unoxidized fatty acid methyl esters (FAME) 18:2, 18:3 and 18:2/16:0. All oils with added oat and
hull extracts had significantly lower CD and significantly higher 18:2/16:0 than oils with added BHT, TBHQ or the control
during 14 days at frying temperature. Phenolic and hydroxy-phenolic antioxidant compounds with acids, alcohols, sugars or
glycerides attached were tentatively identified in the oat and hull extracts by using TLC and Chromatographic sprays.
To whom correspondence should be addressed at Food Science and Human Nutrition Dept., 3367 Dairy Industry Building, Iowa State
University, Ames, IA 50011. 相似文献
AbstractDeep Eutectic Liquids (DELs) have been specially designed, and used for the extraction of bioactive natural products from a bio-waste, since they have attracted much attention from economic and ecological aspects. In this study, an easy, accurate and sensitive detection method has been developed towards a trace amount of oleuropein which is one of the most significant components of the olive leaf extract. TiOx-modified reduced graphene oxide electrode (TiOx-RGO@GCE) has been used as the sensing electrode for the quantitative detection of oleuropein. The structural characterization of TiOx-RGO@GCE has been performed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and atomic force microscopy (AFM) techniques. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques have been implemented to investigate the electrochemical behavior of oleuropein. The electrochemical experiments revealed that the quasi-reversible reaction is the dominant mechanism on the electrode/electrolyte interface. The linear concentration range of 1–12?µM was obtained with the detection limit of 18.7?nM for oleuropein. 相似文献
Abstract The mechanical properties (dynamical, tensile) and morphology by electron microscopy have been studied on PVC mixtures with processing aids of different compatibility with PVC (copolymers of methylmethacrylate, polystyrene, polyvinylacetate) in the temperature range of 20-150°C. It has been found and interpreted that the mechanical properties of PVC in the temperature range of 100-120 °C are favourably influenced by addition of a processing aid, which is compatible with PVC, has a sufficiently high molecular weight and its glass temperature is about 20°C higher than that of PVC. 相似文献