多元复合酶降解黄姜薯蓣皂苷元的工艺研究

研究了多元复合酶降解黄姜薯蓣皂苷工艺条件对黄姜薯蓣皂苷元收率的影响因素。结果表明：采用碱性果胶 酶+单宁酶+半纤维素酶+β-葡萄糖苷酶4元复合酶的组合形式,在酶用量为黄姜量的 1.5%,pH值为6.5,料液比为 1：4（g：g）,50℃ 下酶解 10 h,以乙醇为萃取剂的条件下进行的降解效果最好,薯蓣皂苷元的收率最高可达 4.34%。相比收率仅为 1.61% 的传统的酸解工艺,应用多元复合酶解工艺最高可使黄姜薯蓣皂苷元的收率提高1.69倍。     

黄姜皂素清洁生产工艺的研究

皂素在世界医药学方面有重要的作用。用传统酸解法,提取皂素产率低,环境污染严重。在提取黄姜皂素新工艺的基础上,进一步探讨黄姜提取皂素的清洁生产工艺,即酶解法的清洁生产工艺。清洁工艺对水解酶的用量、反应的时间、温度、pH和溶剂油等方面进行研究,以提高皂素收率。酶解法的清洁生产工艺可从根本上控制污染,节约资源,又提高了产率。     

仙人掌粉水提工艺优化及其化妆品功效评价

对仙人掌粉水提工艺进行了优化。分别进行酶的添加、酶的筛选、酶解时间的确定和离子交换工艺的优化,确定了最终的提取工艺流程。并对仙人掌冻干粉酶提液和水提液的化妆品功效（抗敏舒敏性、保湿性）进行了评价和对纤维素酶提仙人掌粉提取液进行了稳定性测试。结果确定采用纤维素酶,提取的工艺条件为温度50℃,pH为5,g／s为1％,固液比为1：20,酶解时间为1h,离子交换上样比例为1：6。酶提法提取的仙人掌粉提取液在抗敏舒敏性、保湿性上均优于水提法提取的仙人掌粉提取液。纤维素酶提仙人掌粉提取液的稳定性良好。     

Physicochemical Properties and ACE-I Inhibitory Activity of Protein Hydrolysates from a Non-Genetically Modified Soy Cultivar

Arkansas‐grown non‐genetically modified soybean cultivar, R08‐4004, was selected to prepare a protein isolate, which was treated with Alcalase for limited enzymatic hydrolysis. The objective was to optimize the Alcalase hydrolysis condition to produce soy protein hydrolysate (SPH) with high protein yield, low bitterness, and clarity for beverage applications. The degree of hydrolysis ranged between 14 and 52 % during the study at varying incubation times using two different concentrations of Alcalase enzyme. Recovery of soluble protein, between 21 and 53 %, was achieved with a decrease in turbidity. There was an increase in surface hydrophobicity (S₀) which is correlated with bitterness of SPH treated with 1.0 AU (3.2 µL/g) of Alcalase 2.4 L. The sodium dodecyl sulfate‐polyacrylamide gel electrophoresis analysis showed a distinct hydrolysis pattern in which 7S globulin and the two acidic sub‐units of 11S globulin were hydrolyzed extensively in comparison to the two basic sub‐units of 11S globulin. Limited enzymatic hydrolysis produced low molecular weight peptides <17 kDa. Among these SPHs, the one derived after 120 min incubation had the highest soluble protein yield (43 %), low S₀ value (35.4), low turbidity (0.88), and highest angiotensin‐I converting enzyme (ACE‐I) inhibition activity (66.6 %). This hydrolysate has potential use as protein rich nutraceutical for developing many non‐genetically modified food product applications.     

Optimization of the enzymatic hydrolysis conditions of steam‐exploded wheat straw for maximum glucose and xylose recovery

BACKGROUND: The enzymatic hydrolysis of steam‐exploded wheat straw using commercial enzyme complexes has been studied. A cellulase enzyme complex (Accellerase 1500), along with specific xylanase complements (Accellerase‐XC and Accellerase‐XY) provided by Genencor, have been used to enhance glucose and xylose recovery. A systematic study with response surface methodology (RSM) was used to check the effect of the operating conditions: pH (4–5), temperature (50–60 °C) and enzyme/substrate ratio (0.1–0.5 mL g_cellulose^?1) on the enzymatic hydrolysis with Acellerase 1500 to maximize the sugar yield. Xylanases were used as complements to increase the release of xylose. RESULT: Statistical results from ANOVA analysis demonstrated that the enzymatic hydrolysis was clearly improved by temperature and enzyme/substrate ratio. The optimum conditions for higher glucose and xylose releases were obtained with the higher enzyme dosage ratio (0.5 mL g^?1_cellulose), 50 °C and pH 4. CONCLUSION: Model validation at optimum operating conditions showed good agreement between the experimental results and the predicted responses for a confidence level of 95%. The use of the xylanase complements, Accellerase‐XY (accessory xylanase enzyme complex) and Accellerase‐XC (accessory xylanase/cellulase enzyme complex), increases the conversion of hemicellulose. Accellerase‐XC supplementation was more effective, obtaining an increase in yields of glucose and xylose of 11.8% and 23.6%, respectively, using a dosage of 0.125 mL g^?1_cellulose. © 2012 Society of Chemical Industry     

Pathways for the steroidal saponins conversion to diosgenin during acid hydrolysis of Dioscorea zingiberensis C. H. Wright

Diosgenin is an important starting material for the synthesis of steroidal hormone drugs in pharmaceutical industry. Acid hydrolysis of Dioscorea zingiberensis C. H. Wright (DZW) was the key step in the conversion of steroidal saponins to diosgenin in its manufacture factories. The pathways for the conversion of steroidal saponins to diosgenin during acid hydrolysis of DZW were studied experimentally. Three intermediate products and one byproduct were identified. The conversion pathways were from raw steroidal saponins zingiberensis newsaponin (1), deltonin (2), prosapogenin A of dioscin (3) to three intermediate products diosgenin-triglucoside (4), diosgenin-diglucoside (5) and trillin (6), and then to the product diosgenin (7) and byproduct 25-spirosta-3, 5-dienes (8). A maximum diosgenin yield of 2.5% was achieved when reacting in 0.8 M sulfuric acid for 6 h at 120 °C, while the intermediate products were just exhausted. After 6 h, the diosgenin yield decreased, due to the conversion of diosgenin to 25-spirosta-3, 5-dienes (8). The knowledge of the pathways for the conversion of steroidal saponins to diosgenin provide a scientific basis for assessing the performance of acid hydrolysis reaction in diosgenin manufacture factories by monitoring the content of three intermediate products (4-6). It also gives an alternative method for the synthesis of diosgenyl saponins (4-6) from plant material.     

Optimization of the Aqueous Enzymatic Extraction of Oil from Iranian Wild Almond

The seeds of wild almond, Amygdalus scoparia, contain a relatively high quantity of oil. In the current study, aqueous enzymatic extraction of the oil from Iranian wild almond was investigated using a protease and a cellulase to assist the extraction process. The effects of temperature, incubation time and pH on the oil recovery were evaluated using Box?Behnken design from response surface methodology (RSM). A 77.3 % recovery was predicted for oil using aqueous enzymatic extraction procedure at the optimized conditions of RSM (pH 5.76; 50 °C/5 h) when both enzymes were used at 1.0 % level (v/w). In practice, when both enzymes were used, a maximum of 77.8 % oil recovery was achieved at pH 5; 50 °C/4 h. Fatty acid profile, refractive index and saponification value of the aqueous enzymatic extracted oil in the current study were similar to those of the oil extracted with hexane. However, acid value, unsaponifiable matter and p‐anisidine value were higher when compared to those with hexane extracted oil. Peroxide value of the aqueous enzymatic oil was lower than that of oil extracted by hexane. Aqueous enzymatic extraction can be suggested as an environmentally‐friendly method to obtain oil from wild almond.     

Kinetic study of the enantioselective hydrolysis of a meso‐diester using pig liver esterase

A kinetic study of the hydrolysis of the diester dimethyl cis‐cyclohex‐4‐ene‐1,2‐dicarboxylate, to the (1S,2R)‐monoester, catalysed by the enzyme Pig Liver Esterase (PLE) was performed. The effects of the most relevant parameters that influence the enzymatic conversion were studied, such as pH, temperature and concentration of substrate and reaction products. It was concluded that the pH at which the enzyme exhibits a maximum activity is pH 7. At 25 °C PLE presents a better long‐term stability and enantioselectivity than at higher temperatures, although the reaction rate is slower. The kinetic results obtained are well described by the Michaelis–Menten equation, although a slight deviation to this model was observed for low substrate concentrations. Methanol, a co‐product of the enzymatic hydrolysis, was found to act as a non‐competitive inhibitor of the reaction. The Michaelis–Menten parameters were determined and a comprehensive kinetic model, which already accounts for methanol inhibition, is presented. © 2000 Society of Chemical Industry     

Pilot‐plant production of xylo‐oligosaccharides from corncob by steaming,enzymatic hydrolysis and nanofiltration

This paper reports a pilot‐plant production process for xylo‐oligosaccharides (mainly xylobiose and xylotriose) from corncob meal by steaming treatment followed by enzymatic hydrolysis and nanofiltration. The effects of corncob meal pretreatment, steaming temperature and time were investigated in order to obtain maximum extraction of xylan and to minimize the autohydrolysis of xylan into xylose. The enzymatic reaction was carried out using Aspergillus niger AN‐1.15 endo‐xylanase at 55 °C and the optimum enzymatic hydrolysis time was 5 h. The conventional downstream processing for purification of xylo‐oligosaccharides was incorporated with nanofiltration technology, giving benefits of energy saving and removal of monosaccharides. The final product from 40 kg of corncob meal was 10 dm³ of xylo‐oligosaccharide syrup (800 g dm^?3 total sugar), containing 74.5% xylobiose and xylotriose. Copyright © 2004 Society of Chemical Industry     

Functional stabilization of cellulase by covalent modification with chitosan

Chitosan was linked to cellulase (EC 3.2.1.4) from Trichoderma viride by covalent conjugation to periodate‐activated carbohydrate moieties of the enzyme. The modified enzyme contained about 1.5 mol of polymer per mol of protein. The specific activity of the conjugate prepared was 39.8% of the native cellulase. The optimum pH and temperature for cellulase remained unaltered after modification. The thermostability was increased by 8.9 °C for the cellulase–chitosan complex. Thermal inactivation at different temperatures ranging from 65 °C to 80 °C was markedly increased for the polymer‐modified enzyme. The stability within the pH range 1.0–3.2 was also improved for the modified enzyme. © 2001 Society of Chemical Industry     

Lipase‐catalyzed synthesis of partial acylglycerols of acetoacetate

Immobilized Rhizomucor miehei lipase (Lipozyme RMIM) was employed in the synthesis of partial acylglycerols of acetoacetate (C₄H₆O₃, 3‐oxobutanoic acid). Both 1(3)‐sn‐monoacetoacetyl glycerol (MAcG) and 1,3‐sn‐diacetoacetyl glycerol (DAcG) resulting from esterification of glycerol with ethylacetoacetate were isolated and identified by ¹H and ¹³C NMR. An HPLC method for the separation and quantitation of these species was developed. The effects on product yield of coordinate variations in the amounts of enzyme, water, ethyl acetoacetate, and the ratio of immobilizing silica to glycerol were explored. This allowed creation of predictive equations relating these variables to product yield. Reaction conditions were thereby identified and validated under which maximum yields of MAcG and/or DAcG or total ester were predicted. The production of both MAcG and DAcG was markedly sensitive to water, with optimal yields obtained within a narrow range of added water contents. Substantial excesses of ethylacetoacetate ameliorated the inhibitory effect of water. MAcG was effectively produced with the lowest amount of RMIM investigated. It was necessary to use larger amounts of lipase to achieve high yields of DAcG, and even then actual yields were only 30% of theoretical maximum. In the absence of silica only MAcG was produced. Practical applications: Aceotacetyl esters of glycerol are potential prochiral building blocks for further chemical synthesis and exhibit the chemical reactivity of both the acetoacetyl moiety and of glycerol. They are thus of potential use in, for example, the production of biopolymers exhibiting any of a variety of features and functionalities. The use of enzymatic catalysis rather than chemical synthesis for their production offers advantages of reduced degradation and contamination due to the gentler reaction conditions characteristic of enzymatic catalysis, as well as a potential reduction in the costs to procure and dispose of catalyst.     

薯蓣皂素清洁化生产工艺及资源化利用研究进展

现有的薯蓣皂素传统生产工艺具有工艺简单、易操作的优点, 但在产率、能耗及环境污染等方面存在较大问题。本文综述了国内外薯蓣皂素清洁化生产工艺的研究进展, 介绍了两类清洁化生产工艺--传统无机酸水解改进工艺和非无机酸水解工艺, 着重概述了发展前景较好的非无机酸水解工艺, 包括离子交换树脂催化法、离子液体催化法、生物转化法以及热分解处理法, 并比较了不同工艺的优缺点。指出传统无机酸水解改进工艺虽能减少无机酸对环境的污染, 大部分还能提高皂素产率, 但废水废渣的问题仍然没有解决;非无机酸水解工艺几乎零污染排放, 但存在产率低、成本高等不足。本文同时简述了从黄姜提取皂素过程中废水废渣的综合利用方法, 总结了清洁化生产工艺和废渣利用中存在的问题, 提出未来应以提高非无机酸水解工艺的皂素产率为研究重点, 并对废渣的资源化利用不断进行探索和开发。     

Structural Properties and Hydrolysability of Paulownia elongate: The Effects of Pretreatment Methods Based on Acetic Acid and Its Combination with Sodium Sulfite or Sodium Sulfite

The effects of CH₃COOH and Na₂SO₃ pretreatment on the structural properties and hydrolyzability of fast-growing Paulownia elongate were investigated. Acetic acid increased cellulose’s crystallinity and hydrolyzability when combined with alkaline sodium sulfite and sodium hydroxide. The cellulose content increased by 21%, the lignin content decreased by 6%, and the product showed better enzymatic digestibility. With a cellulase dose of 30 FPU/g DM, after 72 h hydrolysis, the hydrolysis yields of glucose and xylose were 78% and 83%, respectively, which were 51% and 69% higher than those of untreated materials. When the enzyme dosage was 20 FPU/g DM, after 72 h hydrolysis, the hydrolysis yields of glucose and xylose were 74% and 79%, respectively. The high hydrolyzability, low enzyme loading, and high hydrolysis yield demonstrate the potential of the proposed system for producing platform sugars from fast-growing Paulownia elongate.     

Active‐Site His85 of Pasteurella dagmatis Sialyltransferase Facilitates Productive Sialyl Transfer and So Prevents Futile Hydrolysis of CMP‐Neu5Ac

Sialyltransferases of the GT‐80 glycosyltransferase family are considered multifunctional because of the array of activities detected. They exhibit glycosyl transfer, trans‐sialylation, and hydrolysis activities. How these enzymes utilize their active‐site residues in balancing the different enzymatic activities is not well understood. In this study of Pasteurella dagmatis α2,3sialyltransferase, we show that the conserved His85 controls efficiency and selectivity of the sialyl transfer. A His85→Asn variant was 200 times less efficient than wild‐type for sialylation of lactose, and exhibited relaxed site selectivity to form not only the α2,3‐ but also the α2,6‐sialylated product (21 %). The H85N variant was virtually inactive in trans‐sialylation but showed almost the same CMP‐Neu5Ac hydrolase activity as wild‐type. The competition between sialyl transfer and hydrolysis in the conversion of CMP‐Neu5Ac was dependent on the lactose concentration; this was characterized by a kinetic partition ratio of 85 m ^?1 for the H85N variant, compared to 17 000 m ^?1 for the wild‐type enzyme. His85 promotes the productive sialyl transfer to lactose and so prevents hydrolysis of CMP‐Neu5Ac in the reaction.     

Ultrasonic and fermented pretreatment technology for diosgenin production from Diosorea zingiberensis C.H. Wright

The present study evaluated the efficiency of ultrasonic and fermented pretreatment technology for diosgenin production from Diosorea zingiberensis C.H. Wright (DZW). The optimum extraction conditions were as follows: ultrasonic pretreatment condition, 20 min, 50 kHz, 100 W; fermented pretreatment condition, 30 °C, 3 d and 0.8 g yeast dosages per 100 g raw materials; acidic hydrolysis condition, 1.5 mol/L sulfuric acid, 4 h; petrol extraction condition, 5 h. Under these conditions, diosgenin yield could reach 2.30%. Scanning electron micrographs indicated morphology changes of materials during diosgenin extraction process. UV-vis and GC-MS analysis revealed wastewater from the new approach contained 20 kinds of organic compounds which were mainly acids, esters, ketones and hydrocarbons. The research indicated the new approach could not only increase 42.5% diosgenin yield, recover 81.6% starch and 50.8% cellulose, but also efficiently reduce 69.7% COD, comparing with the conventional approach.     

利用生物技术协同提取薯蓣皂素

介绍了薯蓣皂素的药用价值 ,回顾并展望了我国的薯蓣资源利用情况。总结了薯蓣皂素当前主要的几种提取工艺 ,直接酸水解法、分离法、超临界CO2 流体萃取法以及自然发酵法的现状 ,并分析了几种工艺中存在的问题。重点探讨了生物催化协同水解提取薯蓣皂素的机理 ,优势及其应用前景。     

Effect of rosehip extraction process on oil and defatted meal physicochemical properties

The physicochemical properties of oil from Rosa affinis rubiginosa seeds were analyzed after extraction by (i) organic solvent, (ii) cold pressing, and (iii) cold pressing assisted by enzymatic pretreatment using a mixture of the Novo-Nordisk A/S products Cellubrix (cellulase and hemicellulase activities) and Olivex (pectinase, cellulase, and hemicellulase activities). There were no significant differences in oil quality parameters, such as iodine value, refractive index, saponification value, unsaponifiable matter, and FA profile, when applying any of the three extraction processes. Although significant variations were observed in FFA content (acid value) and PV of the oil obtained by both of the cold-pressing oil extraction processes, these results were lower than the maximum value established from the Codex Alimentarius Commission. All-trans-retinoic acid content improved by 700% in rosehip oil obtained through cold pressing, with and without enzymatic pretreatment, in comparison with organic solvent extraction. This result is quite important for cosmetic oil because all-trans-retinoic acid is the main bioactive component responsible for the regenerative properties of this oil.     

木质素羟丙基磺甲基化改性及其对纤维素酶水解的影响

通过两步法对木质素进行了羟丙基磺甲基化改性,研究了羟丙基磺甲基木质素对纤维素酶水解的影响及其与酶的相互作用机制。采用红外光谱、核磁氢谱、表面电荷测定、接触角测定等方法对改性木质素的结构和表面特性进行了表征;采用耗散型石英晶体微天平(quartz crystal microbalance with dissipation, QCM-D)研究了改性木质素对纤维素酶非生产性吸附的影响。结果表明：与未改性木质素相比,羟丙基磺甲基化改性封闭了酚羟基,引入了亲水性的磺酸基团。羟丙基磺甲基化木质素具有较高的表面负电性和较低的疏水性,减少了其对纤维素酶的非生产性吸附,从而提高了纤维素的酶水解效率。     

Enzymatic saccharification of dissolution pretreated waste cellulosic fabrics for bacterial cellulose production by Gluconacetobacter xylinus

BACKGROUND: Waste textiles, such as dyed cellulosic and/or polyester blended fabrics have the potential to serve as an alternative feedstock for the production of biological products via microbial fermentation. Dissolution pretreatment was employed to enhance the enzymatic saccharification of dyed and synthetic fiber blended cellulosic fabrics. The fermentable reducing sugars obtained from waste cellulosic fabrics were used to culture Gluconobacter xylinus for value‐added bacterial cellulose (BC) production. RESULTS: Concentrated phosphoric acid was the ultimate cellulose solvent for dissolution pretreatment since 5% w/w cellulosic fabric can be completed dissolved at 50 °C. After regeneration in water, the cellulosic precipitate was subjected to cellulase hydrolysis, resulting in at least 4‐fold enhancement of saccharification rate and reducing sugars yield. The colored saccharification products can be utilized by G. xylinus to produce BC, approximately 1.8 g L^?1 BC pellicle was obtained after 7 days static cultivation. CONCLUSION: Dyed and blended waste fabric can be pretreated effectively by dissolution to produce fermentable sugars by cellulase hydrolysis. Dissolution pretreatment can expose the dyed or polyester fiber covered digestible cellulosic fibers to cellulase and leads to a significant enhancement of saccharification yield. The colored saccharification products have no significant inhibiting effect on the fermentation activity of G. xylinus for BC production. Copyright © 2010 Society of Chemical Industry     

木质素羟丙基磺甲基化改性及其对纤维素酶水解的影响

通过两步法对木质素进行了羟丙基磺甲基化改性,研究了羟丙基磺甲基木质素对纤维素酶水解的影响及其与酶的相互作用机制。采用红外光谱、核磁氢谱、表面电荷测定、接触角测定等方法对改性木质素的结构和表面特性进行了表征;采用耗散型石英晶体微天平(quartz crystal microbalance with dissipation, QCM-D)研究了改性木质素对纤维素酶非生产性吸附的影响。结果表明：与未改性木质素相比,羟丙基磺甲基化改性封闭了酚羟基,引入了亲水性的磺酸基团。羟丙基磺甲基化木质素具有较高的表面负电性和较低的疏水性,减少了其对纤维素酶的非生产性吸附,从而提高了纤维素的酶水解效率。