提高黄原胶丙酮酸含量的发酵实践

丙酮酸是黄原胶分子中最重要的官能团。不同菌种、不同工艺、配方生产的黄原胶丙酮酸含量差别很大。黄单胞菌XC-XH99是经过诱变的黄原胶菌株,溶氧水平是刺激该菌种代谢产物中丙酮酸含量增加的重要因子。生产培养基中的有机酸能有效地提高黄原胶的产率,但会不同程度地抑制丙酮酸含量的合成。      

提高黄原胶丙酮酸含量的发酵实践

丙酮酸是黄原胶分子中最重要的官能团。不同菌种、不同工艺、配方生产的黄原胶丙酮酸含量差别很大。黄单胞菌XC-XH99是经过诱变的黄原胶菌株,溶氧水平是刺激该菌种代谢产物中丙酮酸含量增加的重要因子。生产培养基中的有机酸能有效地提高黄原胶的产率,但会不同程度地抑制丙酮酸含量的合成。     

黄原胶发酵新方法的研究

研究一种无菌体发酵合成黄原胶的新方法，以解决黄原胶发酵后期因高粘度而造成的供氧不足问题，并直接产生不含菌体的发酵产物，降低分离提纯的成本。采用离心法将生长到指数生长后的菌体从发酵液中除去；向无菌体的发酵液中添加高碳无氮培养基，利用菌体产生的胞外酶来合成黄原胶。结果表明：采用胞外酶法，黄原胶产量高于普通发酵法，而发酵液中不含菌体，生产中省去了稀释及分离菌体的工序，因而简化生产工序，降低成本。     

黄原胶

本文详细介绍黄原胶的性能、应用、国内外生产市场现状以及生产工艺，质量标准、技术经济数据等。     

黄原胶发酵条件优化研究

研究pH值、接种量、转速、发酵温度对黄原胶发酵的影响.通过摇瓶发酵,改变试验条件,测定发酵液黏度、粗胶含量来确定较为适合的发酵工艺.正交试验确定了黄原胶的最佳发酵条件为:pH7.2,接种量6%,转速200r/min,发酵温度28℃发酵72h.在此发酵条件下,产量达到25.5g/L,黏度为5569mPa·s.     

黄原胶发酵生产培养基优化研究

黄原胶发酵生产培养基的组成对黄原胶产品质量有较大影响.通过测定发酵液粘度、粗胶含量,研究不同碳源、氮源及无机盐对黄原胶产量和粘度的影响.研究结果表明,碳源对黄原胶质量影响较大,不同碳源之间最终发酵水平有明显差别,当玉米淀粉:蔗糖2∶1时黄原胶产量和粘度最高.氮源的影响次于碳源,确定最佳氮源为黄豆粉.CaCO3能明显提高黄原胶的产量粘度,是无机盐中最大影响因子,CaCO3最优添加量为0.3g/100mL.KH2PO4影响作用不大,差别不显著,当KH2PO4添加量为0.5g/100mL时,黄原胶产量和粘度达到最大.通过正交试验,确定培养基最优配方为:玉米淀粉5g/100mL,蛋白胨0.5g/100mL,KH2PO4 0.4g/100mL,MgSO4 0.05g/100mL,FeSO4 0.025g/100mL,柠檬酸0.025g/100mL,在此条件下,28℃,180r/min发酵培养72h,黄原胶的产量可达到29.88g/L,粘度达到6002mPa/s.     

黄原胶发酵及提取工艺的优化研究

黄原胶是由黄单胞菌属菌分泌的酸性胞外杂多糖,因其具有良好的稳定性和流变性,被广泛用于多种行业。试验在前人研究成果的基础上,以提高黄原胶产量为目的,通过单因素试验确定:在30℃,180 r/min的条件下摇床培养72h,初始碳源浓度6%(蔗糖:淀粉=1:2),接种量10%。提取黄原胶时,加入2%(W/W)的硅藻土,充分震荡10min后离心30min(4 000 r/min),加入1%(W/V)的KNO_3以及3倍体积的混醇(乙醇:异丙醇=3:1)能有效提高提取率。在10L发酵罐中进行小试,产胶率为3.21%。     

黄原胶在印染上的应用

介绍了黄原胶的结构、性能，黄原胶应用于印花、染色、污水处理等，解决了印花常出现的漏浆、花纹不清晰、染色出现泳移等问题，处理的印染废水达到规定要求。     

添加游离丙酮酸对黄单胞杆菌产黄原胶中丙酮酸功能基团含量的影响

在发酵过程中添加游离丙酮酸可以比较明显地提高所产黄原胶分子中丙酮酸功能基团的含量，实验研究表明，添加3．0g/L的游离丙酮酸可以使黄原胶分子中丙酮酸功能基团的含量由4．74％提高到5．29％，提高11，6％，且不影响黄原胶的产胶率，达到33．9g／L。同时通过实验得到游离丙酮酸的最佳添加时间为发酵开始后24h。     

挤板级PMMA热稳定性研究

本文针对影响聚甲基丙烯酸酯(PMMA)热稳定性的不同因素,采用溶解法和本体聚合法两种添加助剂的方式,研究了抗氧剂、酸酐、共聚单体EA和ZnCl_2对PMMA热稳定性及流变性的作用。经热重分析、热机械曲线测定、流变性能测试和厂家试用,结果表明:此法对PMMA热稳定性和流变性有一定改进,其工艺在生产中具有实际意义。     

EFFECT OF SALT ON THE STABILITY OF PROPYLENE GLYCOL ALGINATE/XANTHAN GUM/POLYSORBATE-60 STABILIZED OIL-IN-WATER EMULSIONS

Stabilization mechanism of salt, as a dissolved electrolyte, in oil-in-water emulsions in the presence of stabilizers and/or emulsifiers, propylene glycol alginate, xanthan gum and/or polysorbate-60 has been studied using rheological techniques, particle size analysis and surface tension measurements. Salt affected the stability of the ternary system, propylene glycol alginate/xanthan gum/polysorbate-60, depending on the emulsifier/stabilizer ratio. Creep measurements indicated that low salt concentrations were particularly effective when PGA:X ratios were used in the presence of PS-60. In both PGA:X and PGA:X/PS-60 systems salt did not affect the particle size distribution during aging. Surface tension measurements were in agreement both with particle size distribution and high shear rate experiments.     

EFFECT OF POLYSORBATE-60 ON THE STABILITY OF O/W EMULSIONS STABILIZED BY PROPYLENE GLYCOL ALGINATE AND XANTHAN GUM

The effect of polysorbate-60 in improving the stability of model oil-in-water emulsions formulated with xanthan gum and propylene glycol alginate was studied at two levels of the surfactant; 0.15% and 0.30%. Creep measurements and steady shear measurements as well as surface tension and oil droplet size measurements were conducted to relate rheological and surface properties to improved stability. Higher polysorbate-60 concentration resulted in lower surface tension values which shifted the oil droplet size distribution to a smaller size range; this distribution was a function of aging time at 0.15% weight concentration PS-60. The decay in rheological parameters, particularly Newtonian viscosity, was slower at 0.30% surfactant concentration.     

黄原胶冷水溶部分和热水溶部分的流变特性及其协同作用研究

研究了低浓度黄原胶冷水溶和热水溶部分的流变性,黄原胶在冷水和热水中溶解,其流变性有所不同。考察了浓度、温度、剪切力、pH值、冻融变化等参数对黄原胶溶液的黏度的影响。黄原胶与魔芋胶具有明显的协效性,与卡拉胶、CMC-Na无协效性。     

酒精制醋连续发酵工艺研究

介绍2L气升式反应器二级串连连续发酵生产食醋的工艺。为确定最初发酵条件，试验先用两个2L气升式反应器以6．3％食用酒精、4％黄浆水和水的混合物为发酵培养基在温度30℃条件下半连续发酵，充满系数0．77。当酸度达到要求时都改为连续发酵，同时对进料流量、通气速率进行了研究。得出在进料流量55mL／h、入口处食用酒精6．5％、黄浆水4．3％、通气速率0.188min^-1（vvm）、残留酒精浓度0．35g／100mL时酸度为4．87g／100mL、产酸速率为0．87g/L·h，产酸率76．6％（g/g）。     

海洋红酵母培养条件的研究

通过碳源、氮源及主要营养与环境条件等对海洋红酵母产菌量的影响试验,以及蔗糖、蛋白胨、酵母膏三因素三水平的正交试验,获得了海洋红酵母的最佳发酵条件:蔗糖1.5%,蛋白胨1.0%,酵母膏0.5%,磷酸二氢钾0.15%,硫酸镁0.01%,氯化钠1.0%,初始pH5.0,接种量8%,500mL三角瓶中培养基装量为80mL,发酵温度为28℃,摇床200r/min。在此优化的培养条件下,海洋红酵母的产菌量可达9.7亿个/mL,比优化前发酵培养基产菌量(5.6亿个/mL)提高了73.2%,比单因素试验结果(8.1亿个/mL)提高了19.8%。     

FED-BATCH FERMENTATION FOR RAPID PRODUCTION OF XANTHAN BY XANTHOMONAS CAMPESTRIS

The object of the present work was to optimise inoculum size and nitrogen source for rapid production of xanthan by Xanthomonas campestris by fed-batch fermentation. The fermentation period for production of xanthan by X. campestris decreased from 72 h to 48 h by using 30% (v/v) inoculum instead of the usual 10% level. Among various nitrogenous substances tested in the medium having the C/N ratio of 28, the best concentration of 1.9% (w/v) of xanthan with a viscosity of 10,000 cP was obtained for KNO₃ medium. Intermittent harvests operated for three cycles of 48 h each, using 30% inoculum resulted in xanthan broth of high viscosity (9000 cP) with a concentration of 1.9% and a yield of 68% (w/w). Potassium nitrate was a better suited nitrogen source for the medium used for rapid production of xanthan.     

FED-BATCH FERMENTATION FOR RAPID PRODUCTION OF XANTHAN BY XANTHOMONAS CAMPESTRIS

The object of the present work was to optimise inoculum size and nitrogen source for rapid production of xanthan by Xanthomonas campestris by fed-batch fermentation. The fermentation period for production of xanthan by X. campestris decreased from 72 h to 48 h by using 30% (v/v) inoculum instead of the usual 10% level. Among various nitrogenous substances tested in the medium having the C/N ratio of 28, the best concentration of 1.9% (w/v) of xanthan with a viscosity of 10,000 cP was obtained for KNO₃ medium. Intermittent harvests operated for three cycles of 48 h each, using 30% inoculum resulted in xanthan broth of high viscosity (9000 cP) with a concentration of 1.9% and a yield of 68% (w/w). Potassium nitrate was a better suited nitrogen source for the medium used for rapid production of xanthan.