从发酵液中提取高纯度L-脯氨酸的工艺研究

采用膜过滤技术对L-脯氨酸发酵液进行预处理,使用孔径为1μm的陶瓷膜在30℃-60℃．膜滤压力差选择2．5bar-7．5bar的条件下得到较好的过滤除菌效果。通过树脂吸附试验,考察了pH和不同树脂对L-脯氨酸吸附情况的影响,确定了使用732#阳离子交换树脂进行吸附,上柱发酵液pH3．5,上柱流速0．6BV／h,洗脱液为0．8mol／L NH4Cl,洗脱体积流量为0．4BV／h,高流液经脱色、浓缩结晶后得到L-脯氨酸成品,总提取率为65％。     

从发酵液中提取高纯度L-脯氨酸的工艺研究

采用膜过滤技术对L-脯氨酸发酵液进行预处理,使用孔径为1 μm的陶瓷膜在30℃～60C,膜滤压力差选择2.5bar～7.5 bar的条件下得到较好的过滤除菌效果.通过树脂吸附试验,考察了pH和不同树脂对L-脯氨酸吸附情况的影响,确定了使用732#阳离子交换树脂进行吸附,上柱发酵液pH3.5,上柱流速0.6 BV/h,洗脱液为0.8 mol/L NH4C1,洗脱体积流量为0.4 BV/h,高流液经脱色、浓缩结晶后得到L-脯氨酸成品,总提取率为65％.     

代谢工程改造大肠杆菌合成反式-4-羟基-L-脯氨酸

通过比对筛选,从Micromonospora sp. CNB394中获得高活性的L-脯氨酸-4-羟基化酶,随后利用规律成簇的间隔短回文重复-associated protein 9基因编辑方法,通过强化L-脯氨酸合成途径和引入高活性的L-脯氨酸-4-羟基化酶,构建1株以葡萄糖为碳源合成反式-4-羟基-L-脯氨酸的大肠杆菌基因工程菌HYP15。摇瓶发酵30 h,工程菌的反式-4-羟基-L-脯氨酸产量达到13.6 g/L。5 L发酵罐分批补料发酵40 h,反式-4-羟基-L-脯氨酸产量达到48.6 g/L,糖酸转化率和平均生产强度分别达到21.6%和1.22 g/(L·h),具有良好的工业应用前景。     

旋光法测定L—乳酸钙中L—型的含量

采用旋光法对Ｌ－乳酸钙中具有生物活性的Ｌ－型含量进行了定量测定，结果表明，对纯度较高的乳酸钙和Ｌ－型鉴定有较高的准确度。     

玉米原料生产L—乳酸的几个技术性问题探讨

乳酸是近十年来飞速发展的一种重要有机酸，随着人们物质生活水平的不断提高，其应用领域也不断拓展，世界乳酸的年需求量以15％的速度递增。其中L－乳酸以其可直接参与人体代谢，吸收完全、无副作用，并可生产聚乳酸（PLA）用于消除“白色污染”保护环境等独特的生化价值，引起了世界的关注。我国由于受技术、设备等因素的影响,至今没有形成大规模生产，仍以DL－乳酸为主体。     

酶法生产L—天冬氨酸之研究

本文对利用Ｅ．ｃｏｌｉＡＳ１．８８１细胞内之Ｌ－Ａａｐ酶，以反丁烯二酸及氨为底物转化生产Ｌ－天冬氨酸进行了系统的研究，试验结果表明该酶反应转化率高，Ｌ－Ａｓｐ收率亦较高，Ｌ－Ａｓｐ对反丁烯二酸总收率可达９０％以上。     

乳及乳制品中动物水解蛋白L-羟脯氨酸的检测技术

介绍了检测乳及乳制品中L-羟脯氨酸的常用方法,主要包括高效液相色谱法、高效液相色谱-质谱联用法、氨基酸自动分析仪测定法,毛细管电泳-激光诱导荧光检测法和分光光度法,并对今后乳及乳制品中动物水解蛋白检测技术的发展趋势进行了分析。     

明胶与к-卡拉胶交互作用特性及机理的研究——明胶与卡拉胶共凝胶体的力学特性

本文对明胶与卡拉胶共凝胶体的力学特性进行了研究,小变形实验发现随体系卡拉胶百分数的增加,贮能模量在增加。大变形实验发现共凝胶体的破裂强度及质构随体系两种大分子的配比、体系的pH值、离子强度的变化而变化。     

鱼明胶的开发与应用进展

全文介绍了鱼明胶的性能,生产的主要技术路线与最佳的操作条件及有关进展情况。对现工业化运行的主要鱼明胶生产工艺的技术特点进行了具体的分析和总结,阐述了国内外研究开发的现状与发展趋势。并探讨了扩大应用范围等的前景与市场需求。     

草鱼鱼鳞明胶的提胶工艺及特性研究

探讨草鱼鱼鳞明胶的提胶条件及其特性。采用正交试验研究pH值、温度和时间对鱼鳞明胶品质的影响,利用物性仪、高效液相色谱仪和红外光谱仪等对制备的明胶特性进行分析研究。得到最佳提胶条件:提胶液pH值为6、提胶温度为55℃和时间为6h。得到的明胶提取率为35.56%,黏度为6.04mPa·s,凝胶强度为478.58g,等电点为pH值7.6,亚氨基酸(脯氨酸和羟脯氨酸)含量达21.6%。所得鱼鳞明胶结构稳定,为较高品质的明胶。     

前体物质和碳源补加策略对缺陷短波单胞菌发酵生产L-脯氨酸的影响

对缺陷短波单胞菌(Brevndimonas diminut)JNPP-NSS产L-脯氨酸的补料分批发酵条件进行了研究。结果表明,发酵初始添加50 g/L前体物质谷氨酸,以最适初始葡萄糖浓度100 g/L,于35 h以3.0 g/(L.h)的流速补加葡萄糖,使总糖浓度达120 g/L的补碳方式,L-脯氨酸的合成浓度有所提高。发酵结束,L-脯氨酸的终浓度提高到54.40 g/L,底物葡萄糖对L-脯氨酸的转化率达到0.45 g/g。     

鸡皮明胶的制备及性质研究

目的:以鸡皮为原料,制备一种新型明胶。方法:以酸法提取明胶并检测其性质,探讨了制备条件对鸡皮明胶的粘度、凝胶强度、透明度和色泽等方面影响。结果:其最适提胶条件为:pH4.7,提胶温度60℃,提胶时间3h,在此条件下明胶得率较高,色泽浅白,透明度高,其凝胶强度可达到258 Bloomg。结论:以鸡皮为原料可生产优质明胶,使鸡皮资源得到合理利用。     

Gelatin: The Paramount Food Additive

Of all the hydrocolloids in use today, surely none has proven as popular with the general public and found favor in as wide a range of food products as gelatin. A sparkling, clear dessert jelly has become the archetypal gel and the clean melt-in-the-mouth texture is a characteristic that has yet to be duplicated by any polysaccharide. Despite its apparently unfashionable status, more gelatin is sold to the food industry than any other gelling agent. It is relatively cheap to produce in quantity, and there is a ready supply of suitable raw material. The traditional sources of gelatin include bovine and pig skins and demineralized bones and hooves. However, recent studies have shown that there are viable new sources of gelatin such as marine fish skins and bones. Researchers have further sought to develop gelatin derivatives or modified gelatins like coldwater soluble gelatin, hydrolyzed gelatin and esterified gelatin.     

Gelatin: The Paramount Food Additive

Abstract

Of all the hydrocolloids in use today, surely none has proven as popular with the general public and found favor in as wide a range of food products as gelatin. A sparkling, clear dessert jelly has become the archetypal gel and the clean melt‐in‐the‐mouth texture is a characteristic that has yet to be duplicated by any polysaccharide. Despite its apparently unfashionable status, more gelatin is sold to the food industry than any other gelling agent. It is relatively cheap to produce in quantity, and there is a ready supply of suitable raw material. The traditional sources of gelatin include bovine and pig skins and demineralized bones and hooves. However, recent studies have shown that there are viable new sources of gelatin such as marine fish skins and bones. Researchers have further sought to develop gelatin derivatives or modified gelatins like coldwater soluble gelatin, hydrolyzed gelatin and esterified gelatin.     

Effect of Epigallocatechin Gallate on the Properties of Gelatin

Epigallocatechin gallate was added to gelatin, and the changes in the gelatin were characterized to determine the effects of epigallocatechin gallate modification. The microstructural changes in the samples were analyzed using Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and scanning electron microscopy. The results indicated that the gel strength and thermal stability of gelatin can be improved by appropriate epigallocatechin gallate addition. The optimal final concentration of epigallocatechin gallate was 1.0 g l^?1 in a gelatin solution (66.7 g l^?1). The concentration was also verified using Fourier transform infrared spectroscopy and X-ray diffraction. Covalent bonds were not observed in the epigallocatechin gallate-gelatin samples. Hydrogen bonds were the main molecular interactions observed in the epigallocatechin gallate-gelatin samples. The color of the epigallocatechin gallate-gelatin hydrogels or xerogels was darker because of the epigallocatechin gallate oxidation.