葡萄糖固定床柱异构工艺制备甘露醇

以葡萄糖为原料经过单柱固定床树脂为催化剂化学异构后,再经过离交、加氢、离交、浓缩、结晶、固液分离、干燥,可得到较高收率的甘露醇产品。利用单因素结合正交试验,确定的优化条件为:反应温度96.0℃、糖液流速0.4BV/h、反应液p H 2.0、糖液浓度50%,所得到的甘露糖含量为30.17%,经过加氢后可得到甘露醇含量达30.3%的混醇液。本文所开发的D296单柱固体床树脂为催化剂的工艺,具有连续进出料反应、钼含量低、有效降低后续离交的压力、甘露糖含量较高的优点,非常适合工业生产上采用。     

碎米制备高果糖浆的工艺研究

研究碎米制备高果糖浆的工艺,主要对碎米葡萄糖异构化制取果葡糖液、钙型树脂分离果糖和葡萄糖获得高果糖浆的工艺进行优化。通过单因素和正交试验,得到制取果葡糖液的最优条件：异构酶加酶量9mg/g 碎米葡萄糖、pH7.5、反应温度70℃、反应时间35h;通过正交试验,得到树脂分离制取高果糖浆的最优条件：分离温度70℃、糖液体积分数20%、洗脱液流速4mL/min、进料量40mL。在优化条件下获取的高果糖浆果糖含量为89.64%。     

葡萄糖-牡蛎酶解液美拉德反应体系的抗氧化活性

以牡蛎酶解液与葡萄糖建立美拉德反应体系,以1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl, DPPH）自由基清除率、金属离子螯合能力和还原能力为指标,通过葡萄糖质量分数、反应温度、pH值以及反应时 间4 个因素的单因素试验和正交试验优化得到具有强抗氧化活性的美拉德反应产物适宜反应条件。结果表明,葡萄 糖-牡蛎酶解液美拉德反应产物具有较强抗氧化活性的反应条件为葡萄糖质量分数4%、反应温度120 ℃、pH 7.0、 反应时间120 min。在此组合条件下,牡蛎酶解液美拉德反应得到的反应液的DPPH自由基清除率为93.2%,金属离 子螯合能力为22.5%,还原能力为1.436。     

Maillard反应型虾风味料的制备

目的:以虾头酶解液为主要原料,制备Maillard反应型虾风味料;方法:通过单因素试验确定了还原糖组成及添加量、氨基酸组成及添加量、体系pH、反应温度和反应时间对产物风味的影响,正交试验法进一步优化试验条件;结果:最佳反应条件为:酶解液100g,还原糖4%(木糖:葡萄糖=1∶2),氨基酸3%(甘氨酸∶精氨酸=1∶1),pH 6.5,反应温度121℃,反应时间40min.     

稀酸水解玉米皮制备丁二酸发酵糖液的研究

研究了稀酸水解玉米皮制备丁二酸发酵糖液的工艺条件,通过正交试验及优化调整得到稀酸水解玉米皮的优化工艺条件:水解温度110℃、加酸量1%、粒径20～40目、反应时间90min,总糖收率90.37%,总糖浓度85g/L。其糖液经活性炭脱色,脱色率达92.27%,脱色的总糖损失率低于5%,糠醛含量仅为0.236g/L。经厌氧发酵实验初步验证,玉米皮水解液可替代葡萄糖作为丁二酸发酵的碳源。     

玉米粉制备葡萄糖的糖化工艺优化

以玉米粉为原料,通过高温酶法液化后,添加葡萄糖淀粉酶进行糖化,以还原糖值(DE值)和葡萄糖质量分数(DX值)为评价指标,探讨糖化温度、糖化时间、pH值、葡萄糖淀粉酶添加量对糖化效果的影响。在单因素试验基础上,采用正交试验法对糖化工艺参数进行了优化。结果表明,最佳糖化条件为:糖化温度60℃,糖化时间12h,pH值5.3,葡萄糖淀粉酶添加量45U/g。在此条件下,糖化液DE值为98.24%,DX值为98.16%。     

梅鱼内脏酶解液美拉德反应工艺优化及挥发性物质分析

本文以综合感官评分为评价指标,对梅鱼内脏酶解液与还原糖美拉德反应的条件进行了优化。以吸光度和感官评分作为指标,通过单因素和正交试验,优化美拉德反应条件,并对其反应产物的挥发性成分和抗氧化活性进行分析。结果表明,当反应温度为120 ℃,反应时间为100 min,pH为9.0,葡萄糖与木糖之比为1:1时,梅鱼内脏酶解液美拉德反应的感官效果最高评分为7.51。在此条件下,通过对产物SPME-GC-MS分析,从梅鱼内脏酶解液美拉德反应产物中检测出致香成分89种,其中主要有46.79%醛类、7.26%醇类、1.31%吡嗪类、3.04%呋喃类、1.62%噻唑类等化合物。在最优条件下,通过美拉德反应后,梅鱼内脏酶解液的DPPH自由基清除能力从50.26%增加至73.59%,羟自由基清除能力、超氧阴离子自由基清除能力也有所提高,证明美拉德反应提高了梅鱼内脏酶解液的抗氧化性。     

从海带乙醇预处理液中提取纯化甘露醇的研究

从海带中提取褐藻糖胶的无水乙醇预处理液中提取甘露醇，通过对单因素和正交实验的考察优化了提取甘露醇的条件，结果提取甘露醇的最优条件是：固液比1：10g／mL。提取温度78℃，提取时间3h，总得率达6．86％（含量96．55%，经精制后的甘露醇纯度可达98.70‰     

合成法生产甘露醇工艺优化

研究以葡萄糖为原料合成法生产甘露醇的工艺条件,优化葡萄糖空间异构化、甘露糖氢化、甘露醇结晶以及甘露醇结晶母液中甘露醇和山梨醇色谱分离等工艺参数。结果表明:葡萄糖浓度50%～60%,pH在3～3.5之间,钼酸铵加入量0.2～0.3%,温度100℃～110℃,反应时间1.5 h～2 h,甘露糖转化率可达到30%以上;pH在7～8之间,雷尼镍催化剂用量6%,反应温度120℃～140℃,氢气压力4.5～8 MPa,反应时间1.5 h,甘露醇总收率可达到60%。     

美拉德反应对鱼蛋白酶解物抗氧化活性的影响

文章以鱼糜漂洗液回收蛋白酶解物为原料,分别与葡萄糖、D-果糖、蔗糖、乳糖反应制备美拉德反应产物,探讨美拉德反应对酶解物抗氧化活性的影响。以DPPH自由基清除率为指标,选出葡萄糖作为美拉德反应的最适糖,通过响应面优化试验得出最佳反应条件:加热温度为126.92℃、反应初始pH为10.39、反应时间为3.89h、葡萄糖浓度为3g/dL。在此条件下,羟基自由基清除能力从34.83%增加到61.82%,DPPH自由基清除能力、ABTS自由基清除能力和还原力也有所提高。因此,美拉德反应可以提高鱼糜漂洗液回收蛋白酶解物的抗氧化能力。     

Tea extraction methods in relation to control of epimerization of tea catechins

Effect of water temperature and ethanol concentration on epimerization and extractability of tea catechins was investigated. The results showed that epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) were partially epimerized into gallocatechin gallate (GCG) and catechin gallate (CG), respectively, when tea catechins extract was heated in water solution at 100 °C for 2 h or dry tea was extracted in water at 100 °C. The epimerization of the catechins was inhibited if the tea catechins extract was heated as solid powder and the dry tea was extracted in 50% (v/v) ethanol or in water at 80 °C or below. When the dry tea was extracted in water, the extractability of catechins increased with the increase of extraction temperature up to 100 °C, but there was no statistically significant difference in total catechins between 80 °C and 100 °C. When teas were extracted using ethanol solutions, the highest extractability of total catechins was obtained in 50% (v/v) ethanol for dry tea and in 75% (v/v) ethanol for fresh tea leaf. In order to reveal the real profiles of tea catechins in teas to be tested, dry tea should be extracted in 50% (v/v) ethanol for 10 min, while fresh tea leaf should be extracted in 75% (v/v) ethanol for 10 min. For commercial extraction, temperature should be controlled at 80 °C if water is used as the solvent. Copyright © 2007 Society of Chemical Industry     

Temperature influences epimerization and composition of flavanol monomers,dimers and trimers during cocoa bean roasting

Cocoa consumption is suggested to promote many health benefits, since cocoa is a rich source of flavanols; but amounts and profiles of flavanols depend strongly on the bean type, origin and manufacturing process. Roasting is known as a crucial step in technical treatment of cocoa, which leads to flavanol losses and modifications, especially the epimerization of (−)-epicatechin to (−)-catechin. This study monitors the influence of cocoa bean roasting on the composition of flavanol monomers to trimers, with special focus on epimerization, which was quantified for procyanidin dimers, and also observed for trimers for the first time. Five dimeric and two trimeric potential epimerization products were detected and the extent of epimerization during cocoa roasting was shown to be a function of temperature. The data also showed remarkable variations in the change of flavanol content. The quantified flavanols decreased about 50% in Java beans and increased about 30% in Ivory Coast beans, despite being roasted under equal conditions.     

盐酸精氨酸葡萄糖注射液中葡萄糖含量的测定

目的建立测定盐酸精氨酸葡萄糖注射液中葡萄糖含量的方法。方法选择适宜的pH值,然后通过考察该pH值下溶液旋光度与盐酸精氨酸和葡萄糖浓度的线性关系并测定盐酸精氨酸的比旋度,建立旋光法测定葡萄糖含量的计算公式。结果测定pH值为4.2。在此pH值下,盐酸精氨酸和葡萄糖混合溶液的旋光度与盐酸精氨酸浓度和葡萄糖浓度的复相关系数为0.9999,线性范围分别为2.3～3.0g/100ml和1.8～3.2g/100ml;测得盐酸精氨酸的比旋度为11.54。结论盐酸精氨酸和葡萄糖的旋光度具有加和性,从测得的旋光度中扣除盐酸精氨酸的旋光度,即是葡萄糖的旋光度,葡萄糖的含量可按公式c=2.0852(α-0.1154c1)计算。     

利用便携式血糖仪测定酱油中的葡萄糖

目的:建立一种方便、快速检测酱油中葡萄糖的方法。方法:用便携式血糖仪检测市售酱油中的葡萄糖,并进行重复性试验、回收试验、线性试验。结果:5种不同品牌酱油的葡萄糖浓度分别是25.38、8.28、31.86、8.82、12.06g/L,标准差SD为0.129,批内CV为2.9%,回收率99.9%～101%,平均回收率100.4%,线性方程为y=4.2608x+2.5929,相关系数R2=0.9991,在0.5～5g/L范围内线性关系良好。结论:便携式血糖仪能检测酱油中葡萄糖含量,为检测酱油中的葡萄糖提供了一种便捷的方法。     

Electrochemical determination of glucose using polyaniline electrode modified by glucose oxidase

Polyaniline (PANI) enzyme electrode was formed by immobilisation of Glucose oxidase (GOx) via glutaraldehyde into electrochemically polymerised PANI on graphite electrode. Electrochemical polymerisation of PANI on graphite was performed from aqueous solution of 1.0 mol dm⁻³ HCl and 0.25 mol dm⁻³ aniline at constant current density of 2.0 mA cm⁻². Hronopotentiometric curves of the PANI enzyme electrode obtained at current density of 10 μA cm⁻² were recorded in different glucose concentrations. The linearity response range was between 1.0 and 5.0 mmol dm⁻³ of glucose concentration. The estimated apparent Michaelis–Menten constant, was K_m^′ = 0.30 mmol dm⁻³, which is significantly lower than that of free enzyme.     

Catalytic efficiency of immobilized glucose isomerase in isomerization of glucose to fructose

Glucose isomerase (GI) from Streptomycesrubiginosus was immobilized covalently onto Eupergit C 250 L made by copolymerization of N,N-methylene-bis-methacrylamide, glycidyl methacrylate, allyl glycidyl ether and methacrylamide. The catalytic efficiency of immobilized GI in isomerization of glucose to fructose was found as three fold higher than that of free GI. The residual activity of immobilized GI after 18 reuses in a batch type stirred reactor was about 85% of its initial activity. The thermal stability of immobilized GI was almost same with that of the free GI at 60 °C for 18 h preincubation time. The residual activities of immobilized GI when stored at 5 °C and 25 °C for four weeks were 72% and 69% of the initial activity, respectively. However, free GI retained 88% and 78% of its initial activity at 5 °C and 25 °C upon four weeks storage, respectively. Thus, the use of Eupergit C 250 L immobilized GI instead of free GI is suggested in enzymatic isomerization of glucose to fructose.     

酶法制取葡萄糖的工艺研究

随着现代精细工业的发展,葡萄糖作为基料的社会用量日益增大,用途日趋广泛,制取葡萄糖的工艺研究也成为国内外不间断的课题。本文采用酶法水解与目前先进的过滤、离子交换及蒸发浓缩等下游工程技术结合,研究葡萄糖加工的工艺条件与提高产品纯度和得率的实用技术。通过实验确定最佳工艺条件为：液化时,pH6．0～6．5,温度85℃,时间40min,α-淀粉酶用量0．3％,淀粉浆浓度30％；糖化时,pH4．2～4．5,温度60℃,时间48h,糖化酶用量0．6％。     

Optimising glucose conversion in the production of reduced alcohol wine using glucose oxidase

The use of a glucose oxidase (GOX)-catalase enzyme system for the production of reduced-alcohol white wine is investigated. The process reduces alcohol potential by converting glucose to gluconic acid. Trials were conducted with grape juice and model solution to determine key factors affecting the activity of the GOX system, and to optimise the process for use with grape juice. Under our processing conditions, the low pH of grape juice was found to be a dominant limiting factor in the rate and extent of glucose conversion by GOX. An optimised process for glucose conversion (up to 87%) was developed after investigation of the effects of enzyme dosage, sparging, aeration and mixing rates, and temperature. Maximum GOX activity was observed during the first 4 to 6 h of treatment, after which a significant decrease in the rate of gluconic acid formation and glucose degradation occurred. An expected increase in titratable acidity and concurrent decrease in pH during GOX treatment was also observed, and is attributable to an increase in the juice gluconic acid concentration of ca 73 g/l.     

Conversion of glucose in lactase-hydrolyzed whey permeate to fructose with immobilized glucose isomerase

The maximum conversion of glucose to fructose in lactase-hydrolyzed whey permeate by glucose isomerase was approximately 52% at .1 g enzyme/ml substrate after 7 h incubation at 60 degrees C. Removal of minerals from the substrate was essential for enzyme activity. The dependence of the enzyme on Mg++ and Co++ for activity in the presence of high ash concentration was demonstrated. Optimum Mg++ and Co++ additions were 250 and 100 ppm, respectively. The isomerization reaction was enhanced more when both 100 ppm Mg++ and 50 ppm Co++ were added. Hydrolyzed isomerized lactose whey syrup with sweetness equivalent to sucrose was successfully produced through enzymatic isomerization of glucose in lactase-hydrolyzed whey permeate after supplementation with pure glucose. Fructose in hydrolyzed isomerized lactose whey syrup was effectively separated from other sugars by Dowex 1X8-200 anion exchange resin in the bisulfite form.     

Effect of multivalent cations on the enzymatic determination of glucose with glucose oxidase]

Iron and copper ions, in a concentration greater than 10(-4) M, inhibit the indicator reaction of a glucose oxidase-peroxidase reagent for the enzymatic determination of glucose, when weakly complexing buffers or buffer-free reaction media are used. The addition of EDTA and other complexing agents or, time-dependently, the buffer ions themselves reverse the inhibition to a great extent. The discussed mechanism of inhibition is based on the assumption that the metal ions share in the re-oxidation of the co-enzyme of glucose oxidase.