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Shu Jun WANG Wen Yuan GAO Jing Lin YU Pei Gen XIAO 《中国化学快报》2006,17(9):1255-1258
Dioscoreae (Chinese name Shanyao), the rhizome of various species of genus Dioscorea opposita Thunb.(Dioscoreaceae), has been used as an important invigorant in traditional Chinese medicine (TCM) for many years1. Starch, the most abundant carbohydrate in … 相似文献
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Mayra Esthela Gonzlez-Mendoza Fernando Martínez-Bustos Eduardo Castao-Tostado Silvia Lorena Amaya-Llano 《Molecules (Basel, Switzerland)》2022,27(11)
Starch is the most abundant carbohydrate in legumes (22–45 g/100 g), with distinctive properties such as high amylose and resistant starch content, longer branch chains of amylopectin, and a C-type pattern arrangement in the granules. The present study concentrated on the investigation of hydrolyzed faba bean starch using acid, assisted by microwave energy, to obtain a possible food-grade coating material. For evaluation, the physicochemical, morphological, pasting, and structural properties were analyzed. Hydrolyzed starches developed by microwave energy in an acid medium had low viscosity, high solubility indexes, diverse amylose contents, resistant starch, and desirable thermal and structural properties to be used as a coating material. The severe conditions (moisture, 40%; pure hydrochloric acid, 4 mL/100 mL; time, 60 s; and power level, 6) of microwave-treated starches resulted in low viscosity values, high amylose content and high solubility, as well as high absorption indexes, and reducing sugars. These hydrolyzed starches have the potential to produce matrices with thermo-protectants to formulate prebiotic/probiotic (symbiotic) combinations and amylose-based inclusion complexes for functional compound delivery. This emergent technology, a dry hydrolysis route, uses much less energy consumption in a shorter reaction time and without effluents to the environment compared to conventional hydrolysis. 相似文献
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Catalytic Hydrolysis of Lipophilic Amino Acid Esters by Metallomicelles as Carboxypeptidase A Models
Metallondcellesasthemodelofhydrolyticmetalloenzymes.havebegunrecently'.Exam-plesarethemetal-ioncomplexesoflipophilicinddazoles2andpyridines'co-ndcelledwithsurfactantS.Hereinwereportthecomplexesofanovelmacrocyclicl2-membereddioxotetradrineligandbearingbis-hydroxygroupsasfunctionalpendantSwhichcanmindcthecatalyticfunctionofcarboxypeptidaseAinndcellarmedia.2,6-Dioxo-l,4,7,lo-tetraazacyclo1(O.2Og,1.onuno1)'anddodecylglycidylether(O.54g,2.2nunol)'wererefluxedinEtOH(3OoInL)for24h.Thesolventwase… 相似文献
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Theoretical Studies on Mechanism and Rate Constant of Gas Phase Hydrolysis of Glyoxal Catalyzed by Sulfuric Acid 下载免费PDF全文
Ming-qiang Huang Shun-you Caia Ying-min Liao Wei-xiong Zhao Chang-jin Hu Zhen-ya Wang Wei-jun Zhang 《化学物理学报(中文版)》2016,29(3):335-343
The gas phase hydration of glyoxal (HCOCHO) in the presence of sulfuric acid (H2SO4) were studied by the high-level quantum chemical calculations with M06-2X and CCSD(T) theoretical methods and the conventional transition state theory (CTST). The mechanism and rate constant of the ve di erent reaction paths are consid-ered corresponding to HCOCHO+H2O, HCOCHO+H2O H2O, HCOCHO H2O+H2O, HCOCHO+H2O H2SO4 and HCOCHO H2O+H2SO4. Results show that H2SO4 has a strong catalytic ability, which can signi cantly reduce the energy barrier for the hydration reaction of glyoxal. The energy barrier of hydrolysis of glyoxal in gas phase is lowered to 7.08 kcal/mol from 37.15 kcal/mol relative to pre-reactive complexes at the CCSD(T)/6-311++G(3df, 3pd)//M06-2X/6-311++G(3df, 3pd) level of theory. The rate constant of the H2SO4 catalyzed hydrolysis of glyoxal is 1.34×10-11cm3/(molecule s), about 1013 higher than that involving catalysis by an equal number of water molecules, and is greater than the reaction rate of glyoxal reaction with OH radicals of 1.10×10-11cm3/(molecule s) at the room temperature, indicating that the gas phase hydrolysis of glyoxal of H2SO4 catalyst is feasible and could compete with the reaction glyoxal+OH under certain atmospheric condi-tions. This study may provide useful information on understanding the mechanistic features of inorganic acid-catalyzed hydration of glyoxal for the formation of oligomer 相似文献
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Cassava pulp contains significant amount of starch which can be hydrolyzed to glucose, and further converted to different kinds of chemicals, such as lactic acid, fumaric acid, and ethanol. Microwave irradiation is an alternative method for starch hydrolysis, and the addition of activated carbon has been reported could increase glucose yield at lower temperature in water medium. This research was to study the effects of two types of activated carbon on the acid hydrolysis of cassava pulp under microwave irradiation. The experiment was conducted at two microwave power level (30% and 50%), each with heating duration of 5, 7.5 and 10 min in 0.5% sulfuric acid medium. The addition of activated carbon with superior adsorption capacity in cassava pulp suspension resulted in lower glucose yield than the one without the addition of activated carbon at both power levels. On the other hand, the addition of activated carbon with inferior adsorption capacity resulted in much higher glucose yield than the one without the addition of activated carbon at microwave power 30% and slightly lower glucose yield at microwave power 50%. However, activated carbon with higher adsorption capacity was superior to the other one in suppressing the formation of colored secondary degradation materials. The highest glucose yield (91.52%) was obtained in the hydrolysates from the treatment at microwave power 50% for 10 min without the addition of activated carbon. 相似文献
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蛋白质水解阶段对氨基酸组成分析的影响 总被引:10,自引:0,他引:10
水解是蛋白质氨基酸组成分析的重要步骤,水解质量的好坏直接影响到分析结果的正确与否,蛋白质的水解受到很多因素的影响,如温度,时间、水解试剂,添加剂,水解方法等,本文对近10年来蛋白质组成分析中中有关蛋白质水解问题的研究进进行了评述,对最近几年出现的一些新的水解方法如酸性水解中的气相水解,微波辐射水解,膜上蛋白质和印迹水解,聚丙烯酰安凝胶中蛋白质的水解,敏感氨基酸的水解以及水解过程中影响氨基酸外消旋化的因素等作了简要的介绍。 相似文献
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Kim P. P. Pastukhova G. V. Peretrutov A. A. 《Russian Journal of Applied Chemistry》2001,74(1):167-169
The statics and kinetics of hydrolysis of nitrosylsulfuric acid were studied at the initial sulfuric acid concentrations in the range 60-76 wt % and temperatures in the range 20-100°C or 30-130°C. The results were compared with the published data. 相似文献
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Metallomicelles as the model of hydrolytic metalloenzymes have begun recently1. Examples are the metal-ion complexes of lipophilic imidazoles2 and pyridines3 co-micelled with surfactants. Herein we report the complexes of a novel macrocyclic 12-membered di-oxotetraamine ligand bearing bis-hydroxy groups as functional pendants which can mimic the catalytic function of carboxypeptidase A in micellar media. 相似文献
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Procyanidins are contained in various foods, and their effects on starch hydrolysis have been reported. In Japan, black soybeans, which contain a trimeric procyanidin, procyanidin C1 (proC1), are cooked with rice and used to prepare dumplings. In this study, the effects of proC1 on the pancreatin-induced formation of reducing sugars and starch hydrolysis were studied using potato starch and corn starch. ProC1 inhibited both reactions; the inhibition was greater in potato starch than corn starch when added to heated potato starch and corn starch. When heated with proC1, its inhibitory effects decreased, especially in potato starch, suggesting the important role of proC1 itself for the inhibition of potato starch hydrolysis. ProC1 also inhibited the hydrolysis when added to heated, longer amylose (average molecular weight: 31,200), and the inhibition decreased when heated with the amylose. On the other hand, proC1 could not inhibit the hydrolysis when added to heated, shorter amylose (average molecular weight: 4500), but could when heated with the amylose, suggesting the important role of the degradation products of proC1 for the inhibition. We discuss the mechanism of the proC1-dependent inhibition of amylose hydrolysis, taking the molecular weight into account. 相似文献
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Vivek Sharma Kent D. Rausch James V. Graeber Shelly J. Schmidt Philip Buriak M. E. Tumbleson Vijay Singh 《Applied biochemistry and biotechnology》2010,160(3):800-811
Starch samples with 0% or 30% amylose were subjected to four different liquefaction enzyme treatments (at various temperature and pH conditions) followed by simultaneous saccharification and fermentation (SSF). Resistant starch (RS) measurements were conducted for the initial starch sample, after liquefaction and after SSF. Initial RS was higher for 30% amylose starch samples (16.53 g/100 g sample) compared with 0% amylose (0.76 g/100 g sample). Higher initial RS resulted in lower conversion of starch into sugars and lower final ethanol yields. The four enzymes hydrolyzed RS, but in varying amounts. Higher temperature liquefaction hydrolyzed a larger portion of RS, resulting in higher ethanol concentrations and lower final residual solids (non-fermentables), whereas lower temperature liquefaction hydrolyzed a smaller portion of RS and resulted in lower ethanol concentrations and higher final residual solids. Decreases in resistant starch after high temperature liquefaction were 55% to 74%, whereas low temperature liquefaction decreases were 11% to 43%. For all enzyme treatments, RS content of starch samples decreased further after SSF. 相似文献
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NDAMANISHAJeanChrysostome WANGHui GUOLi-ping 《高等学校化学研究》2005,21(4):431-435
After the synthesis of polyaniline in the presence of ferrocenesulfoniccarboxylic acid, its influence on the electrochemical reaction of methanol was studied. The result indicates that the ferrocenyl in ferrocenesulfoniccarbexylic acid plays an important role in the electrocatalytic oxidation of methanol. CH3OH is adsorbed on PANI-Fc before its electrocatalytic oxidation. When the concentration of methanol is 2 mol/L, it begins to be oxidized. The effect of scan rate on the electrochemical reaction of methanol was also studied and 5 mV/s was favourable. It is another method to insert a metal catalyst in polyaniline without its electrodeposition. 相似文献
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G. A. Gizatulina E. N. Chebotok V. Yu. Novikov I. N. Konovalova 《Russian Journal of Applied Chemistry》2005,78(5):791-793
The kinetics of acid hydrolysis of N-acetylglucosamine at different temperatures and reagent concentrations was studied. A mathematical model of the hydrolysis was proposed. The rate constant and activation energy of deacetylation were calculated.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 807–809.Original Russian Text Copyright © 2005 by Gizatulina, Chebotok, Novikov, Konovalova. 相似文献
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Acid hydrolysis of chitin and chitosan recovered from shells of sea Crustacea was studied by exclusion high-performance liquid chromatography. 相似文献
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A simple calorimetric method was employed to study the kinetics of the hydrolysis of the solventless TMOS-water mixtures, under ultrasound stimulation, as a function of the concentration of oxalic acid. The reaction rates were obtained, in relative units, from the measured thermal peak of the reaction as a non-separated function of both the sonication time and the instantaneous temperature of the medium. For concentrations of oxalic acid below 0.01 M, polycondensation reaction starts before complete hydrolysis. For concentrations of oxalic acid above 0.01 M, hydrolysis is complete and, in addition, the inverse of the time, as measured from the starting of ultrasound action until the maximum hydrolysis heat release, was found to be a reasonable relative measure of the average hydrolysis rate constant. The average hydrolysis rate constant was found to be proportional to the square root of the molar concentration of the oxalic acid. This result is in agreement with the literature if we assume small dissociation degree for the catalyst in such a solventless alkoxyde-water medium. 相似文献
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This study investigated the optimization of the enzymatic processing conditions for polylactic acid (PLA) fibers using enzymes
consisting of lipases originating from different sources. The hydrolytic activity was evaluated taking into consideration
the pH, temperature, enzyme concentration, and treatment time. The structural change of the PLA fibers was measured in the
optimal treatment conditions. PLA fiber hydrolysis by lipases was maximized for lipase from Aspergillus niger at 40 °C for 60 min at pH 7.5 with 60% (owf) concentration, for lipase from Candida cylindracea at 40 °C for 120 min at pH 8.0 with 70% (owf) concentration, and for lipase from Candida rugosa at 45 °C for 120 min at pH 8.0 with 70% (owf) concentration. There was a change in protein absorbance of the treatment solution
before and after all lipase treatments. The analyses of the chemical structure change and structural properties of the PLA
due to lipase treatment was confirmed by tensile strength, differential scanning calorimetry, wide-angle X-ray scattering
diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy. 相似文献
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