In order to extend the applicability of the regioselective enzymatic carboxylation of phenols, the substrate scope of o ‐benzoic acid (de)carboxylases has been investigated towards complex molecules with an emphasis on flavouring agents and polyphenols possessing antioxidant properties. o ‐Hydroxycarboxylic acid products were obtained with perfect regioselectivity, in moderate to excellent yields. The applicability of this method was proven by the regioselective bio‐carboxylation of resveratrol on a preparative scale with 95% yield.
The intrinsic viscosity of four poly(N-vinylpyrrolidone) fractions in the molecular weight range from 2.75 × 104 to 3.5 × 105 was measured in a cosolvent mixture of water/sodium decyl sulphate with different sodium decyl sulphate concentrations below its critical micellar concentration. Measurements were made in the temperature range 25?40°C. The value of the a and K parameters of the Mark-Houwink-Sakurada equation were determined. The values obtained for a were in general high, as expected for good solvents. Using the Stockmayer-Fixman equation with the data, Kθ and B, i.e. the short and long range interaction parameters respectively, were calculated, which showed the existence of a conformational change at 12.3 mM sodium decyl sulphate concentration, at all temperatures. The polymer-solvent interaction parameter X for the fraction of molar mass 3.5 × 105 was also determined. 相似文献
The Brassica oleracea industry generates large amounts of by-products to which value could be added because of the characteristics of their composition. The aim was to extract different fibre fractions from broccoli stalks to obtain potential new added-value ingredients. Using an ethanol and water extraction procedure, two fibre-rich fractions (total fibre fraction, TFB, and insoluble fibre fraction, IFB) were obtained. These fractions were analysed to determine the nutritional, (poly)phenols and glucosinolates composition and physicochemical properties, comparing the results with those of freeze-dried broccoli stalks (DBS). Although TFB showed a higher content of total dietary fibre, IFB had the same content of insoluble dietary fibre as TFB (54%), better hydration properties, higher content of glucosinolates (100 mg/100 g d.w.) and (poly)phenols (74.7 mg/100 g d.w.). The prebiotic effect was evaluated in IFB and compared with DBS by in vitro fermentation with human faecal slurries. After 48 h, the short-chain fatty acid (SCFA) production was higher with IFB than with DBS because of the greater presence of both uronic acids, the main component of pectin, and (poly)phenols. These results reveal that novel fibre-rich ingredients—with antioxidant, technological and physiological effects—could be obtained from broccoli stalks by using green extraction methods. 相似文献
Poly(vinylidene fluoride) (PVDF) and poly(ethylene–butylacrylate–glycidyl methacrylate) (PTW) are polymers with weak interfacial adhesion. Blends based on PVDF and PTW (50/50?w/w) with poly(butylene succinate) (PBS) (0, 1, 3, 5, 7?wt%) are obtained by compression molding. The estimation of interfacial interaction among PVDF, PTW, and PBS and the properties of PVDF/PTW blends are investigated. The optimal content of PBS to form a co-continuous morphology in PVDF/PTW blends is proposed, indicating that the beneficial effect of PBS (7?wt%) on interfacial adhesion is observed. Overall, estimating interfacial adhesion is a critical issue for designing PVDF/PTW blend with excellent performance, which has a prospect in coating. 相似文献
The sensitivity of the carbonyl stretching vibration of methyl acetate to interactions with the surroundings is re-examined through FTi.r. analyses and Fourier self deconvolution. The relevant conclusions permit a study of the mixtures of methyl acetate and methyl pivalate with various fluorinated polymers. Evidence is given for the existence of hydrogen bonding between poly(vinylidene fluoride) and these model compounds of poly(methylmethacrylate). Arguments are put forward in favour of a similar behaviour in poly(vinylidene fluoride)/poly(methylmethacrylate) blends. 相似文献
Using circular dichroism, the helix contents of sodium poly(L -glutamate) (PLGNa) and poly(L -lysine) hydrobromide (PLLHBr) in their weak and strong polyelectrolyte complexes have been estimated in aqueous alcohol solutions. Helix (de)stabilization observed in the systems is compared with earlier results on the PLGNa/PLLHBr polyion complex. 相似文献
