Study of Cross-Linking between Boric Acid and Different Types of Polyvinyl Alcohol Adhesive

Polyvinyl alcohol (PVA) is water-soluble polymer manufactured by the saponification of polyvinyl acetate. The physical properties and its specific application depend on the degree of hydrolysis. To enhance the properties of different hydrolyzed PVA grades, it is generally chemically modified with various cross-linkers. Here, different degree hydrolyzed PVA grades with enhanced properties were achieved by cross-linking with boric acid. These samples were then characterized by Differential Scanning Calorimetry (DSC) and Gel permeation chromatography (GPC). For further analysis a film of samples were prepared by casting on glass plate. The effects of amount of boric acid and degree of hydrolysis of PVA on performance properties like tensile strength, pencil hardness and thermal properties like glass transition temperature were studied. The results showed that by cross-linking there was an increase in mechanical strength and thermal property.

Kinetic study of alkaline protease 894 for the hydrolysis of the pearl oyster Pinctada martensii

A new enzyme (alkaline protease 894) obtained from the marine extremophile Flavobacterium yellowsea (YS-80-122) has exhibited strong substrate-binding and catalytic activity, even at low temperature, but the characteristics of the hydrolysis with this enzyme are still unclear. The pearl oyster Pinctada martensii was used in this study as the raw material to illustrate the kinetic properties of protease 894. After investigating the intrinsic relationship between the degree of hydrolysis and several factors, including initial reaction pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time, the kinetics model was established. This study showed that the optimal conditions for the enzymatic hydrolysis were an initial reaction pH of 5.0, temperature of 30°C, substrate concentration of 10% (w/v), enzyme concentration of 2 500 U/g, and hydrolysis time of 160 min. The kinetic characteristics of the protease for the hydrolysis of P. martensii were obtained. The inactivation constant was found to be 15.16/min, and the average relative error between the derived kinetics model and the actual measurement was only 3.04%, which indicated a high degree of fitness. Therefore, this study provides a basis for the investigation of the concrete kinetic characteristics of the new protease, which has potential applications in the food industry.

Study on enzymatic hydrolysis of soybean β-conglycinin using alkaline protease from Bacillus subtilis ACCC 01746 and antigenicity of its hydrolysates

Due to its beneficial health effects,the use of soybean protein has shown a continuous increase,but concerns regarding the allergenicity of soybean antigenic protein have also increased.This study aimed to evaluate the hydrolytic effects of a non-commercial alkaline protease isolated from the Bacillus subtilis ACCC 01746 on soybeanβ-conglycinin and the allergenicity of its hydrolysates.Alkaline protease of the strain was separated by precipitation method of organic solvents,and theβ-conglycinin was separated by alkali-solution and acid-isolation and purified by use of gel column.Using the degree of hydrolysis(DH)and inhibition rate as evaluation indexes,the enzymatic hydrolysis parameters ofβ-conglycinin was optimized by single factor and L_(9)(3^(4))orthogonal tests,so as to explore the effect of the protease on the hydrolysis degree and the antigenicity ofβ-conglycinin hydrolysates.The results showed that the native enzyme existed as an 18.3 kDa monomer with a 430 U/g maximum activity.The purity ofβ-conglycinin was 84.8%.The single-factor test results showed that DH showed the oppostie trendency with the inhibition rate,and the increase of protein concentration causedmonotone increasing and monotone decreasing of the inhibition rate and the DH,and the optimal protein concentration was 30 mg/mL.The optimization results showed that pH had the largest impacts on both DH and the inhibition rate,followed by enzyme dosage,hydrolysis temperature and hydrolysis time.Under the optimum hydrolysis conditions of protein concentration 30mg/mL,enzymedosage0.7%,hydrolysis time40min,temperature 55°C and pH8.5,the DH reached the highest of 76.28%,and the inhibition rate was the lowest of 27.03%,which was reduced greatly compared with that before optimization.These results suggested that alkaline protease appeared to show a relatively high effeciency in lowering soybean allergenicity,making it possible to produce low-allergenicity soybean protein.

Study on the Technologic Optimization for Hydrolysis of Silver carp By-products

The hydrolysis process for Silver carp by-products was studied. Protein hydrolysate was prepared with proteolytic enzyme, Alcalase. Hydrolysis conditions were optimized by the regression model of three factors five levels quadratic rotation perpendicular regressive design. The optimum hydrolysis conditions of hydrolyzing the protein of Silver carp by-products were determined to be concentration of enzyme (E/S) 3.33%, pH 8.54, hydrolyzing temperature 58 ℃, reaction time 90 min, concentration of substrate 8%. Nitrogen recovery was more than 75%.

Enzymatic Hydrolysis of Fish Frames Using Pilot Plant Scale Systems

Papain was used to hydrolyse fish frames under controlled conditions at a batch-pilot plant scale- process, for the production of fish protein hydrolysates (FPH). Mass balance calculations were carried out so that the rate of hydrolysis, rate of protein solubilisation and yields could be estimated. Almost complete hydrolysis could be achieved in 1 hour, at 40oC, with no pH adjustment, at 0.5% (5 g.kg-1) enzyme to substrate ratio (E/S, were S is Kjeldahl protein) using whole fish frames (including heads and flaps). This was achieved both with the addition of water (1/1 to 2/1 frames/water) but more importantly from commercial considerations without the initial addition of water (after mincing of the fish material). The degree of protein solubilisation ranged between 71% - 86% w/w. Four different processes are described, namely: 1) a soluble spray-dried FPH powder 2) a liquid FPH 3) a partly soluble, spray dried FPH powder and 4) a crude, drum-dried protein for animal consumption. The amino acid profile of the FPH was identical to that of the parent substrate (fish frames).

羊乳清蛋白部分和深度水解工艺、水解物致敏性及肽谱分析

利用羊乳清蛋白制备低致敏性配料是目前乳品工业的研究热点。乳清蛋白是乳中主要的蛋白质之一,也是引起婴幼儿过敏反应的主要成分,将蛋白质水解为小分子肽是降低其致敏性的有效方法。以山羊乳清蛋白为原料,研究了部分水解乳清蛋白和深度水解乳清蛋白的水解工艺和水解物特性(水解度、分子质量分布和β-乳球蛋白抗原性),并利用液相色谱串联质谱法(L C-MS/MS)比较了部分水解和深度水解工艺中过敏表位酶切位点的差异。研究结果表明,中性蛋白酶和碱性蛋白酶对羊乳清蛋白水解效果较好,其中碱性蛋白酶的水解度最高,达21.26%。经电泳分析,单酶水解后的产物中仍存在大分子多肽链,深度水解工艺需要复合酶水解。在酶底比为4000 U/g时,使用碱性蛋白酶在pH值为10.0、温度为55℃条件下水解羊乳清蛋白1.0 h,部分水解产物的水解度为12.31%,分子质量在5 kDa以下的多肽占95.18%,β-乳球蛋白抗原性下降率为9.40%。中性蛋白酶和碱性蛋白酶的质量比为1∶1,酶底比为6000 U/g,在pH值为8.5、温度为50℃条件下,水解羊乳清蛋白3.0 h,深度水解产物的水解度为35.58%,分子质量低于3 kDa的多肽为97.26%,β-乳球蛋白抗原性下降率为40.97%。部分水解和深度水解均能破坏β-乳球蛋白的大部分过敏表位,但相较于部分水解,深度水解能更大程度地降低乳清蛋白的致敏性。研究旨在为低致敏性羊水解乳清蛋白的生产提供一定的理论参考。

银杏种仁分离蛋白水解产物的制备及其抗氧化活性研究

采用碱性蛋白酶、菠萝蛋白酶和米曲霉蛋白酶对银杏种仁分离蛋白(GBSPI)进行水解,并通过体外DPPH自由基、羟基自由基和超氧阴离子自由基清除实验评价GBSPI水解产物的抗氧化活性。研究结果表明:碱性蛋白酶、菠萝蛋白酶和米曲霉蛋白酶水解产物的得率分别为93.60%、60.00%和46.80%,水解度分别为13.76%、6.28%和5.55%。3种酶水解产物对DPPH自由基、羟基自由基和超氧阴离子自由基均具有较好的抑制作用,其中,碱性蛋白酶水解产物具有最强的抗氧化活性,其对DPPH自由基、羟基自由基和超氧阴离子自由基的IC 50值分别为5.29、0.35和7.01 g/L。

复合酶解南美白对虾虾头制备ACE抑制肽的工艺优化

以南美白对虾虾头为原料,利用复合酶解法制备血管紧张素转化酶(angiotensin-converting enzyme,ACE)抑制肽。在传统酶解法基础上,对酶解效率较高的蛋白酶进行筛选和复配,结合双酶复合酶解法水解虾头蛋白。以ACE抑制率和水解度为指标,通过单因素和响应面试验对制备工艺进行优化,确定复合蛋白酶组合方式及配比等工艺参数。得到虾头蛋白源ACE抑制肽的最佳酶解条件为料液比1∶7(g/mL)、酶添加量400 U/g、初始pH7.5、酶解温度50℃、复合酶(胰蛋白酶∶风味蛋白酶)配比2.29∶1(U/U)、酶解时间2.17 h,在此条件下虾头蛋白水解度达71.48%,ACE抑制率达83.57%,酶解效率与优化前的单酶水解相比提高35.05%。结果表明南美白对虾虾头经胰蛋白酶和风味蛋白酶酶解后具有较高的ACE抑制活性。

不同提取方法提取马铃薯蛋白的研究

该实验以新鲜马铃薯为原料,采用醇溶法、盐溶法、碱溶法3种方法提取马铃薯蛋白,测定其纯度和提取率,结果表明,醇溶法提取的马铃薯蛋白纯度为94.5%,提取率为4.5%,提取效果最好。通过SDS-PAGE电泳分析,醇溶法提取的马铃薯蛋白亚基条带多,分子量范围广,并且在分子量为25~40 kDa范围内含量很高,说明醇溶法能有效提取马铃薯蛋白质的各个组分;进一步研究其理化性质,发现醇溶法提取的蛋白质持油性、持水性、乳化性、乳化稳定性更好;水解度分析显示醇溶法提取的马铃薯蛋白水解度更高。因此,在这3种方法中,醇溶法是比较经济、所得蛋白质性质较好的提取方法。

酶法制备花生α-葡萄糖苷酶抑制肽的工艺优化

为促进花生蛋白资源的开发利用及发挥花生肽的降血糖作用,采用碱溶酸沉法制备花生蛋白,并利用不同商品蛋白酶水解花生蛋白制备花生肽。以α-葡萄糖苷酶抑制率为评价指标,对蛋白酶进行了筛选。在此基础上,采用单因素试验和响应面试验对花生α-葡萄糖苷酶抑制肽的制备工艺进行了优化。另外,考察了花生蛋白水解度和花生肽α-葡萄糖苷酶抑制活性的相关性。结果表明:与其他商品蛋白酶相比,胰蛋白酶制备的花生肽的α-葡萄糖苷酶抑制活性最高;酶法制备花生α-葡萄糖苷酶抑制肽的最优工艺条件为将花生蛋白于95℃加热5 min进行预处理,采用胰蛋白酶水解,水解时间62 min,加酶量8.9%,底物质量浓度4.1 g/100 mL,在最优条件下花生肽α-葡萄糖苷酶抑制率达到(68.82±0.24)%,此时花生蛋白的水解度为10.09%;水解度在8.0%~11.5%范围内与花生肽的α-葡萄糖苷酶抑制活性呈显著正相关。综上,花生蛋白经胰蛋白酶水解后得到的花生肽对α-葡萄糖苷酶具有显著的体外抑制活性。

羊肉蛋白酶解工艺优化及酶解液中氨基酸含量分析

采用新疆阿勒泰羊后腿肉为原料,以蛋白酶添加比例、酶解时间、pH值及酶解温度为自变量,以蛋白水解度为评价指标,采用单因素和响应面试验探究木瓜蛋白酶与风味蛋白酶组成的复合酶最佳酶解条件,并测定酶解液中氨基酸含量。结果表明:最佳酶解条件为木瓜蛋白酶与风味蛋白酶体积比1∶2、酶解时间5 h、pH5.5、酶解温度45.7℃,此条件下蛋白水解度达到44.22%,与理论值误差较小。最优条件下制备的酶解液中测定出16种氨基酸,谷氨酸(63.84 g/kg)、甘氨酸(48.37 g/kg)、组氨酸(41.02 g/kg)含量较高,甲硫氨酸(0.07 g/kg)含量最低。

辣木籽醒酒肽的酶解制备工艺优化

旨在促进辣木籽醒酒肽的开发利用,以辣木籽蛋白粉为原料,蛋白水解度和辣木籽醒酒肽的乙醇脱氢酶(ADH)激活率为考察指标,采用单因素实验和响应面法优化辣木籽醒酒肽的制备工艺。结果表明,辣木籽醒酒肽制备的最佳酶解工艺条件为料液比1∶20、碱性蛋白酶添加量5.0%、酶解pH9.0、酶解温度63℃、酶解时间142min,在此条件下辣木籽蛋白水解度为12.23%,辣木籽醒酒肽的ADH激活率为22.16%。综上,以辣木籽为原料制备醒酒肽具有良好的发展前景。

畜禽源抗氧化肽的酶解工艺优化

以鸭肝为原料,通过酶解法制备鸭肝抗氧化肽。从8种蛋白酶中筛选出风味蛋白酶为酶解鸭肝肽的最佳用酶。以水解度和抗氧化性为评价指标,通过单因素试验、响应面试验探究料液比、酶解温度、酶解时间、酶解pH值和酶用量对鸭肝抗氧化肽活性和水解度的影响。响应面优化的最佳酶解条件为料液比1∶10(g/mL)、酶解温度50℃、酶解时间3.9 h、酶解pH6.2、酶用量4100 U/g。在此条件下,鸭肝肽的DPPH·清除率可达93.25%,水解度为15.03%。

聚丙烯酰胺对机制砂亚甲蓝值的影响机理研究

机制砂已成为我国建设用砂的主要来源。通过亚甲蓝试验考察了阴离子型聚丙烯酰胺(HPAM)的分子量及水解度对机制砂亚甲蓝(MB)值的影响规律,借助循环伏安(CV)试验、扫描电镜和傅里叶变换红外光谱分析,探究了HPAM与MB之间的作用机理。研究结果表明:随着HPAM质量浓度的增加,机制砂MB值呈现阶梯式增大的趋势;在相同水解度和浓度时,随着HPAM分子量增大,分子链中的酰胺基团数量和水解产生的阴离子活性基团含量增多,与MB溶液中的阳离子(C16H18N3S+)结合形成的电化学活性复合物增加,HPAM水解产生的含氧官能团与MB分子中的苯环间的氢键作用力增强,导致机制砂MB值增大;在相同分子量和浓度时,随着HPAM水解度提高,水解HPAM的分子链有效长度增大,与MB分子之间的静电引力以及氢键作用力增强,导致机制砂MB值增大。

超声辅助NaCl浸泡对熟化黑豆结构和消化特性的影响

为探究超声辅助NaCl浸泡对黑豆的结构和消化特性的影响规律,采用扫描电镜、红外光谱、X射线衍射等分析NaCl对黑豆结构的作用机制,利用热特性、吸水率、膨胀率等明确黑豆熟化过程性质的变化,并分析淀粉体外消化特性。结果表明,超声辅助NaCl浸泡后的黑豆粉颗粒致密度降低,颗粒之间间隙变大,抑制了淀粉结晶区域损伤。随着NaCl浓度的升高,黑豆颗粒的膨胀率比清水浸泡升高了28%、48%、56%,硬度明显下降,糊化度升高至40%、43%、45%,黑豆淀粉水解率分别下降到19.05%、17.93%、17.48%。以上结果说明钠离子可抑制淀粉消化,本研究NaCl浸泡处理可为开发低GI黑豆食品奠定理论基础。

玉米及其制品中淀粉糊化度测定方法的研究

本试验旨在建立一种操作简便、精确度高、重复性好的快速测定玉米及其制品淀粉糊化度的测定方法。试验将全糊化试样、待测试样及空白试样与糖化酶溶液混合,水解生成葡萄糖,使用3,5-二硝基水杨酸显色,以比色法测定各溶液吸光度,从而计算淀粉糊化度。本试验通过对影响淀粉糊化度检测结果的关键因素即糖化酶添加量、酶解时间、酶解温度及样品粒度的试验探究,确定了最佳条件:样品过60目分析筛,每0.3 g样品使用1000 U糖化酶,在40~45℃条件下酶解60 min。在此条件下测定玉米、玉米淀粉、膨胀玉米及膨化玉米的淀粉糊化度,结果与行业标准《NY/T4125-2022饲料中淀粉糊化度的测定》进行对比,P值均大于0.05,RSD均小于2%,表明本研究测定淀粉糊化度筛选出的试验条件准确度高、精密度高,并且简便易行,可降低试剂风险及成本,便于检测人员进行质量控制及测定。

酶解改性技术在提高核桃蛋白粉溶解性中的研究

核桃蛋白粉因具有较高的营养价值而被广泛应用于食品中,但是传统工艺制备的核桃蛋白粉溶解性较差,使其附加值严重降低。本文采用胰蛋白酶对核桃蛋白粉进行酶解改性,研究酶解改性工艺对核桃蛋白粉溶解性的影响。结果表明,当酶用量为0.3%、料液比为9∶1、酶解温度为40℃、酶解时间为40 min时,核桃蛋白粉的氨溶指数较高,水解度较低,核桃蛋白粉的溶解性较好。

DHS钢板治疗粗隆间骨折50例临床分析

目的探讨粗隆间骨折手术中应用DHS钢板的临床应用及效果。方法回顾性分析2007年5月～2012年5月入住我院的50例粗隆间骨折患者的临床资料,应用DHS钢板进行治疗,并将其作为观察组,另外选择同期收治于我院的50例粗隆间骨折患者作为对照组,应用解剖型锁定钢板法(LCP)进行治疗。比较两组治疗疗效、髋关节肿胀程度、髋关节活动度(ROM)的情况。结果观察组的优良率、髋关节肿胀程度、ROM与对照组差异均有统计学意义(P<0.05或P<0.01),显示观察组较对照组具有较为优势的治疗效果。结论 DHS钢板用于粗隆间骨折手术之中,疗效显著,患者髋关节肿胀程度、ROM等均较传统的治疗方法有明显的改善,应在临床上加以推广并应用。

两种DH模型的机器人运动学建模对比研究

针对机器人运动学建模的规范性和通用性问题,以空间四自由度机器人为研究对象,论述了两种DH模型的规范化建模过程,分析了两者的差异性,同时运用两种规范化的DH模型推导了空间四自由度机器人的运动学方程,并利用Robotic Toolbox进行仿真。结果表明Modified-DH模型具有更强的适用性和通用性,且建模过程更加灵活、清晰。为机器人运动学建模模型选择和规范建模过程提供了参考。

Isolation of Nanocellulose from Cotton Cellulose and Computer Modeling of Its Structure

Nanocellulose is a new class of derivatives of cellulose, which is characterized by high crystallinity, surface area, degree of dispersion, ability to decomposition by microorganisms and etc. There is high attention solving problems of obtaining nanocellulose and its application as high quality filler for polymers, biodegradable materials, additives for papers, clotting dispersion and etc. Obtaining of particles of nanosized nanostructure on the base cellulose, studying of processes of their formation, properties and creation nanotechnology on this basis give the chance to obtain materials with unique properties. In this work nanocellulose was obtained from cotton cellulose by hydrolysis with sulfuric acid, ultrasonic dispersion and microwave irradiation. The properties and structure of nanocellulose are investigated by AFM, IR-spectroscopic, X-ray methods. Nanocellulose has rod-like shape with sizes 50 - 300 nm in length and 10 - 40 nm in diameters and spherical shape with sizes 50 - 300 nm depending on the synthesis conditions of obtaining. Quantum-chemical methods have been used to calculate the electronic characteristics of nanocellulose;the change in the energy difference between HOMO and LUMO is shown, showing the change in reactivity and the manifestation of specific properties.