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Utilization of renewable resources is gaining more emphasis and large quantities of solid wastes are produced by the forestry
industry. However, there is a significant lack of transformation of such wastes into potentially novel products. The barks
of various Pinus species from different regions of Turkey (P. pinea, P. sylvestris, P. nigra) and Germany (P. parviflora, P. ponderosa, P. sylvestris, P. nigra) were extracted by supercritical CO2 extraction. Different sources of variability including location and species were evaluated for their active constituents,
(−)-catechin, (−)-epiatechin, (−)-catechin gallate, and taxifolin, applying HPLC, radical scavenging activities (RSA), and
total phenol analysis. The total amounts of flavan-3-ols (9.916 mg/g) were the highest in P. pinea extract harvested from Aydin, having the hottest climate and longest duration of sun (P < 0.01). In addition, P. pinea had the highest RSA (81.0 %) and total phenol value (83.0 mg GAE/g). 相似文献
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I.H. AkgunA. Erkucuk M. PilavtepeO. Yesil-Celiktas 《The Journal of Supercritical Fluids》2011,57(1):31-37
The effects of supercritical carbondioxide extraction was investigated to compare previously validated extraction methods on total alkannin yield with Alkanna tinctoria collected form Antalya, Turkey. A two-step process was used; extraction of alkannin derivatives with supercritical CO2 followed by alkaline hydrolysis of alkannin derivatives. A Box-Behnken exprerimental design was used to evaluate the effect of three variables, pressure (50-350 bar), temperature (30-80 °C) and CO2 flow (5-20 g min−1) at 1:30 ratio of alkanna root:CO2 amount. Response surface analysis revealed that the data were adequately fitted to a second-order polynomial model with R2 0.9665 and the most effective variable was pressure (P ≤ 0.05). Optimum conditions were determined as 80 °C, 175 bar, 5 g min−1 CO2 flow yielding the highest total alkannins (1.47%) which was higher than conventional hexane extraction (1.24%) providing a solvent-free alternative for industrial production. 相似文献
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O. Yesil-Celiktas G. Girgin H. Orhan H. J. Wichers E. Bedir F. Vardar-Sukan 《European Food Research and Technology》2007,224(4):443-451
Methanolic extracts from the leaves of Rosmarinus officinalis (rosemary) harvested from different locations of Turkey at four different times of the year were analyzed by HPLC, and their
radical scavenging capacities and antioxidant activities were studied by various assays. The amounts of carnosol, carnosic
acid and rosmarinic acid, active constituents of rosemary, varied in different geographical regions of growth, and also showed
a seasonal variation. The levels of the constituents were higher in the warm months of June 2004 and September 2004. The antioxidant
activities of 12 extracts were determined by in vitro DPPH radical scavenging activity, by Trolox equivalent antioxidant capacity
(TEAC), and by reversing H2O2-induced erythrocyte membrane lipid peroxidation (EMLP). The two antioxidant enzyme activities of human erythrocyte, namely
superoxide dismutase (SOD) and catalase (CAT), after in vitro incubation with the extracts, were also examined in order to
see whether the observed effects are related to altered enzymatic efficiency. The resulting values were correlated with active
metabolite and total phenol contents of the extracts. The results indicated that the plants harvested in September possessing
higher levels of active constituent had superior antioxidant capacities compared to the ones collected at other times. With
respect to the location, plants harvested from the Izmir region had lower total phenol and active constituent levels resulting
in poorer antioxidant activity. 相似文献
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Deniz Senyay-Oncel Hasan Ertas Ozlem Yesil-Celiktas 《Journal of the American Oil Chemists' Society》2011,88(7):1061-1069
Utilization of renewable resources and development of new processes aimed at converting these materials into value added bio-products
are gaining more emphasis. The scope of this study was to optimize supercritical CO2 extraction (SFE) parameters such as pressure, temperature and flow rate for the yields of unsaturated fatty acids from Pistacia terebinthus berries by a Box-Behnken statistical design. All samples were analyzed for fatty acids by GC-FID. The most effective variables
were pressure (P < 0.005) and flow rate (P ≤ 0.005). Maximizing the evaluative criteria for dependent variables (oleic acid, linoleic acid and linolenic acid), optimal
conditions were determined to be 240 bar, 60 °C and a flow rate of 16 g/min yielding 51.2% oleic acid, 26.5% linoleic acid
and 1.0% linolenic acid. The amounts of unsaturated fatty acids in SFE samples (81.3%) were higher than the hexane (74.3%)
and were similar to that of cold press samples (80.1%). High concentrations of unsaturated fatty acids can indicate the utilization
of the berries as a major dietary source and demonstrate challenges for industrial application of SFE as a green technology. 相似文献
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Various physical, chemical and genetic approaches have been applied in order to enhance enzyme stability and activity. In this study, the aim was to investigate the capability of sub- and supercritical carbon dioxide to alter the stability and activity of α-amylase as an alternative technique. The effects of operational parameters such as pressure (50-300 bar), temperature (28-80 °C), CO? flow (2-10 g min?1) and time (60-180 min) were evaluated in regard to the activity and stability of fungal based α-amylase from Aspergillus oryzea. The activity of untreated enzyme was determined as 17,726 μmol/ml/min. While both sub- and supercritical conditions enhanced the activity, the increase in flow rate had an adverse effect and the activity was decreased by 28.9% at a flow rate of 10 g min?1 under supercritical conditions. Nuclear magnetic resonance (NMR) spectra of untreated enzyme and treated samples exhibiting the lowest and the highest activities were almost identical except for the chemical shifts observed at the lowest activity sample from 4.0 to 4.4 ppm which were assigned to protons of hydrogen-bonded groups. Optimum conditions were determined as 240 bar, 41 °C, 4 g min?1 CO? flow and 150 min of process duration yielding 67.7% (29,728 μmol/ml/min) higher activity than the untreated enzyme providing fundamental basis for enzymatic applications. 相似文献
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Microsystem Technologies - The aim of this study was to develop a model that describes enzymatic conversion in a microfluidic system along with convective and diffusive transport of... 相似文献
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The aim of this work was to optimize the glycoside composition of Stevia rebaudiana leaves using supercritical fluid extraction (SFE). A Box-Behnken statistical design was used to evaluate the effect of various values of pressure (150–350 bar), temperature (40–80 °C) and concentration of ethanol-water mixture (70:30) as co-solvent (0–20%) by CO2 flow rate of 15 g min−1 for 60 min. The most effective variables were co-solvent concentration (P < 0.005) and temperature (P ≤ 0.005). Evaluative criteria for both dependent variables (stevioside and rebaudioside A yields) in the model was assigned maximum. Optimum extraction conditions were elicited as 211 bar, 80 °C and 17.4% which yielded 36.66 mg/g stevioside and 17.79 mg/g rebaudioside A. Total glycosides composition were close to those obtained using conventional water extraction (64.49 mg/g) and a little higher than ethanol extraction (48.60 mg/g) demonstrating challenges for industrial scale application of SFE. 相似文献
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