谷氨酸发酵液除菌体提取谷氨酸

作者论述了近几年来,国内一些味精厂及研究所、对谷氨酸发酵液除菌体和后提取方法,相继开发了高速离心机分离、阳离子絮凝聚剂分离、中空纤维膜超滤、调整pH 加热使菌体凝聚过滤除菌体,以及常温等电提取或浓缩等电提取谷氨酸、提取率明显提高,幅度5—8%。     

谷氨酸分析仪测定发酵液中γ-聚谷氨酸的实验条件研究

研究了pH值和培养基主要组分对谷氨酸分析仪测定谷氨酸含量的影响,确定了γ-聚谷氨酸水解的最佳条件.结果表明,在pH=5～10内,溶液的pH值对谷氨酸分析仪的测定结果没有显著影响;模拟发酵液体系的试验,发酵液中各主要成分含量的变动范围±25%时,对测定结果也没有明显影响.采用正交试验优化了γ-聚谷氨酸的水解条件.以2 mL发酵液为例,其最佳水解条件为4 mL浓度为6 mol/L浓盐酸,真空度为0.1 MPa,110℃,24 h.     

液氨在谷氨酸提取中的应用

目前被国内很多味精厂采用的锌盐法提取谷酸工艺,为了在碱性条件下使谷氨酸与硫酸锌(ZnSO_4·7H_2 O)作用,生成难溶解的谷氨酸锌盐沉淀,达到从发酵液中分离谷氨酸的目的,必须耗用大量的液碱调节pH值,不仅增加生产成本,而且影响谷氨酸质量。今年以来,我们依据液氨既可充当合成谷氨酸的氨基,又同时具备调节pH值的功能这一属性,将液氨取代液碱应用于锌盐法提谷氨酸的工艺,取得了十分显著的效果。     

γ-聚谷氨酸提取条件的优化

目的:通过实验对γ-聚谷氨酸提取条件进行优化得到一组产量高的最优条件。方法:利用枯草芽孢杆菌通过发酵生产得到含有γ-聚谷氨酸的发酵液,再以异丙醇作为沉淀剂提取发酵液中的产物。通过响应曲面分析方法设计三因素三水平Box-Behnken实验优化提取条件。最后利用薄层色谱和红外光谱对产物进行结构鉴定。结果:利用Design-Expert软件处理数据并优化得到一组最佳提取条件:异丙醇的添加倍数为4.5,沉淀温度为-5℃,沉淀时间为23h。在最优条件下得到γ-聚谷氨酸的产量为0.1796g/10mL,预测精确度达99%。结论:在低温下用异丙醇沉淀发酵液中的产物是一种有效可行的提取γ-聚谷氨酸的方法。     

甲醇-乙醇分步沉淀法提取γ-聚谷氨酸

采用非单一有机溶剂即甲醇-乙醇分步沉淀法从发酵液中提取聚谷氨酸(γ-PGA),通过响应面法对聚谷氨酸(γ-PGA)提取条件进行优化。在初步考察单因素影响的基础上,以BBD(Box-Behnken design)法设计考察有机溶剂沉淀倍数、沉淀pH、沉淀时间3个因素对γ-PGA提取纯度的交互影响,用Design-Expert v8.0.6.1软件对BBD实验数据进行分析处理。试验得到的最佳提取条件为:有机溶剂沉淀倍数为3.48、沉淀pH为8.13、沉淀7.30 h,γ-PGA提取纯度为75.16%,提取率83.77%,预测精准度达99.02%。     

冷冻(冰晶)浓缩法在谷氨酸发酵液提取中的应用与研究

用冷冻浓缩工艺对谷氨酸发酵液进行浓缩实验,准确分析温度、pH值、结晶时间、搅拌操作等因素对冰结晶浓缩分离效果的影响,由此确定最适合于谷氨酸的冷冻浓缩等电点的条件.     

pH值对聚谷氨酸发酵液粘度及聚合物结构的影响

生产中聚谷氨酸的发酵液非常黏稠(粘度达1.71Pa.s),这使除菌体提取聚谷氨酸非常困难。通过加酸或碱调节发酵液pH<5或pH>8可明显降低发酵液的粘度(其中pH3.5时粘度仅为pH6.5时的1/50左右)。将pH3.5的发酵液离心除菌(10 000×g,10 min)后超滤浓缩(滤膜孔径0.45μm,平均压力0.08 Mpa)1倍,再加入95%乙醇提取-γPGA,与pH中性时相比,可减少50%以上的能量消耗及40%的溶剂,但聚谷氨酸损失约10%。加酸或加碱处理可使发酵液中-γPGA的分子结构发生改变,分子质量降低,这对生产高分子质量的聚谷氨酸不利,但对生产低分子质量产物是适宜的。     

聚谷氨酸发酵液菌体去除工艺研究

针对地衣芽孢杆菌(Bacillus licheniformis)CGMCC3336发酵生产得到的聚谷氨酸发酵液粘度高,传统的板框过滤、平板超滤等菌体分离方法分离菌体非常困难的问题,本文研究了酸化絮凝工艺进行菌体分离的可行性,研究确定了最适合聚谷氨酸发酵液菌体分离的工艺参数:利用50%(v/v)的硫酸调节发酵液pH 3.0,酸化絮凝8h,经过200L工艺放大证明,酸化絮凝除菌体是一条适合聚谷氨酸发酵分离菌体的新工艺。     

锌盐等电点法提取谷氨酸

发酵液中的谷氨酸在一定的pH条件下能与锌离子结合，生成难溶解于水的谷氨酸锌（C5H7O4Zn·21/2H2O）沉淀物，在pH6．3时谷氨酸锌在水溶液中溶解度最低，从而将谷氨酸从发酵液中分离出来。然后，将谷氨酸锌配成一定浓度，用盐酸或硫酸溶解到谷氨酸的等电点，使之析出谷氨酸结晶，除去母液，水洗，经离心机分离后得到湿谷氨酸。     

提高异常谷氨酸发酵液提取收率方法的探讨

大家都知道,味精(L—谷氨酸单钠盐),现在主要是通过糖质原料的谷氨酸发酵来生产的。然而,如何高收率、高质量地从谷氨酸发酵液当中提取谷氨酸,发酵液质量的优劣是一个关键因素。特别是对难于提取的异常发酵液,如何采取有效的方法,来     

工业发酵液中谷氨酸结晶介稳区测定及其对生产的意义

本文测定了在三种体系内,即纯水、含1％NH_4离子浓度水溶液及实际工业发酵液体系中谷氨酸的溶解度和超溶解度曲线。将这些曲线用数学表达式拟合,便可计算出谷氨酸等电点结晶的介稳区宽度。实验结果表明,介稳区宽度在纯水、含1％NH_4离子浓度的水溶液和实际工业发酵液体系内相应逐渐变窄,即谷氨酸在这些体系中的溶解度逐渐变大。其拟合的饱和度和超饱和度曲线具有以下形式:C=ae~(bt)从介稳区宽度数学模型出发,提出了用计算机控制的连续等电结晶新工艺来提高谷氨酸收率的设想。     

陶瓷膜在谷氨酸发酵液除菌过程中的应用

对陶瓷膜在谷氨酸发酵液除菌过程中的应用进行了实验研究。实现了除菌、洗菌、浓缩过程连续化操作 ,浓缩倍数达到 2 5倍。选择了合适孔径的陶瓷膜 ,确定了膜的操作条件和再生方式。当加水量为发酵液量的 0 1倍时 ,水洗后谷氨酸收率 >99 7%。除菌率 >99 98%。     

Recovery of lactic acid by repeated batch electrodialysis and lactic acid production using electrodialysis wastewater

Repeated batch electrodialysis for lactic acid recovery was investigated using lactic acid solution and fermentation broth. In both cases, lactate fluxes averaged more than 7.0 moles/m2.h, lactate recovery reached more than 99% for all the batch runs, and specific energy consumption per unit lactate transported was lower than 0.25 kWh/kg-lactate. When electrodialysis wastewater was used as a fermentation medium, supplemented with 100 g/l glucose, up to 92.4 g/l lactic acid was produced with a productivity of 0.67 g/l.h. In addition, when electrodialysis wastewater was supplemented with 150 g/l whole-corn flour hydrolyzate and 5 g/l corn steep liquor, 2.5-fold and 1.8-fold increases in lactic acid productivity and maximum cell growth, respectively, were achieved, as compared with lactic acid fermentation using electrodialysis wastewater supplemented with glucose only.     

不同电渗析条件下酱油主要风味组分迁移规律研究

采用电渗析法对酱油进行脱盐处理时，可回收大量具有特殊风味的盐液。该实验研究了不同电渗析条件下脱盐对酱油各组分迁移情况的影响，并分析了盐液的风味物质构成。结果表明，电渗析电压的变化对酱油中氯化钠（NaCl）迁移效率的影响远大于氨基酸态氮及总酸。在电渗析电压13 V、处理时间30 min条件下，酱油的氨基酸态氮（AAN）及总酸（TA）的损失率较低，且NaCl脱除率达41.97%，盐液中NaCl、AAN、TA含量分别为6.60 g/100 mL、0.135 g/100 mL、0.208 g/100 mL。盐液中含有以丙氨酸、亮氨酸及赖氨酸为主的15种游离氨基酸（FAA），总游离氨基酸含量为0.31%。其中鲜味氨基酸的迁移率较低，甜味及苦味氨基酸的迁移率较高。盐液中初步检测到17种风味物质，其中包含苯乙醇、3-甲硫基丙醇、3-甲基-1-丁醇、糠醇、4-乙基愈创木酚等多种酱油特征性风味物质。     

Recovery of Glutamic Acid from Fermentation Broth by Membrane Processing

Recovery of glutamic acid from the fermentation broth by membrane processing was investigated. The broth was ultrafiltered (UF), and the retentate was diafiltered (DF) to wash out the remaining product. The dilute DF permeate was concentrated by reverse osmosis (RO). Recovery of glutamic acid by UF (R_uf) was a function of the volume concentration ratio (VCR); R_uf= 1.052 – 1.048/VCR. High VCR, however, decreased UF flux (J) (J = 14.2 – 5.4 In VCR). The rate of recovery by DF was a function of the turnover ratio. A linear relationship between flux and pressure was found during RO. Separation of glutamic acid from bacterial cells by membrane processing could improve the efficiencies of subsequent evaporation and crystallization processes.     

Antioxidant activity and γ-aminobutyric acid (GABA) content in sea tangle fermented by Lactobacillus brevis BJ20 isolated from traditional fermented foods

GABA-producing lactic acid bacteria were isolated from kimchi and salt-fermented Jot-gal, which are traditional Korean fermented foods. The strain, BJ-20, isolated from salt-fermented Jot-gal (cod gut), possessed the highest GABA-producing ability in MRS broth with 1% monosodium glutamate (MSG), as determined by thin layer chromatography. The BJ-20 strain was identified as Lactobacillus brevis and designated as L. brevis BJ20. A sea tangle solution was fermented over 5 days to produce GABA using L. brevis BJ20. During fermentation, the GABA concentration dramatically increased, while the glutamic acid concentration decreased. This result indicates that the glutamic acid was converted to GABA by L. brevis BJ20 in the fermented sea tangle solution. Furthermore, the fermented solution exhibited strong antioxidant activities, such as DPPH scavenging, superoxide scavenging, and xanthine oxidase inhibition, which were higher than those of BHA as a positive control.     

氨基酸溶液电渗析脱盐过程的研究

测定了不同浓度和流速下的盐水和氨基酸盐溶液的极限电流密度,分析了浓度、流速、氨基酸含量等因素对电渗析极限电流密度的影响,提出了描述电渗析特性的数学模型。初步研究了应用电渗析对氨基酸盐溶液进行处理时,流速和电压对脱盐率和氨基酸回收率的影响,用较低的流速在接近极限电流密度的条件下操作能达到最好的分离效果。     

微生物絮凝剂产生菌NX-2的筛选和合成条件的研究

从土壤中筛选分离到 1株高效絮凝剂产生菌NX 2 ,鉴定为枯草芽孢杆菌 (Bacillussub tilis)。在含谷氨酸和葡萄糖的培养基中培养 ,其发酵产物粘度高 ,对高岭土、活性炭等固体悬浮颗粒具有显著的絮凝作用 ,而缺少谷氨酸和额外碳源则不能产生絮凝活性。NX 2培养并产生絮凝活性的碳源可采用葡萄糖、蔗糖、麦芽糖、甘油、可溶性淀粉和果糖 ,氮源采用酵母膏、蛋白胨等有机氮源或铵盐等无机氮源。通过核磁共振等手段对分离提纯的样品进行结构表征 ,鉴定其为γ 聚谷氨酸。     

Removal of salt and organic acids from solution used to season salted Japanese apricots (ume) by electrodialysis, precipitation and adsorption

With the aim of repeatedly reusing the solution used to season salted ume (Japanese apricot), we investigated its desalting and deacidification by electrodialysis, precipitation, and adsorption. Although NaCl and acids could be easily removed from used seasoning solution by electrodialysis, useful substances such as amino acids were removed at the same time. Precipitation using Ca(OH)2 could remove only organic acids, but the treated solution became bitter. Two weakly basic commercial resins, DIAION WA30 and Chitopearl CCS, adsorbed organic acids selectively. Chitopearl CCS in particular selectively adsorbed citric acid in the used seasoning solution without also adsorbing useful substances. The equilibrium data of a citric acid, which was a main organic acid, were correlated by the Langmuir equation. The saturation capacity decreased with increasing concentrations of NaCl in the solution but the equilibrium constant did not change. By combining electrodialysis and adsorption, NaCl and organic acids could be removed while amino acids largely remained. The resultant solution was considered to be suitable for repeated reuse.     

味精清洁生产蒸发凝结水再利用研究

在味精清洁生产工艺中 ,利用四效蒸发技术来浓缩谷氨酸等电结晶母液 ,所得的蒸发凝结水因COD值稍高而不能直接排放。为解决这一问题并节约水资源 ,文章中研究了将凝结水作为配料水应用于味精生产的可行性。通过与自来水进行比较 ,考察了其对液化、糖化和发酵过程的影响。分别用凝结水和自来水作为配料水进行制糖和发酵实验 ,结果二者均无明显差异。这一结果表明 ,蒸发凝结水应用于谷氨酸发酵是可行的。