槐豆胶的流变性及与黄原胶的协效性研究

本文主要对槐豆胶的流变性及槐豆胶与黄原胶的协效增稠性和协效凝胶性进行了研究。结果表明:槐豆胶具有较高的粘度,当胶浓度为1％时,其粘度为660mpa·s;浓度、剪切力、温度、酸碱、冻融等变化与槐豆胶的粘度都有较大的关系;槐豆胶还有一非常显著的特性即是与黄原胶的协效增稠性和协效凝胶性,可作为理想的黄原胶的增稠剂和凝胶剂。     

改性黄原胶酯化条件的优化及结构的表征

为了提高黄原胶的速溶性和粘度,将黄原胶进行改性处理。将黄原胶与马来酸酐进行酯化反应,探讨了黄原胶与马来酸酐摩尔比、反应时间和反应温度等因素的影响,以取代度为指标,利用响应面方法确定,该酯化反应的最优条件为:黄原胶与马来酸酐摩尔比1∶11.5、反应时间24.4 h、反应温度66℃。对改性黄原胶进行红外光谱、光散射和X-射线衍射等结构表征,表明酯化改性成功,且进一步解释了速溶性和粘度提高的原因。改性黄原胶细胞毒性实验,显示无毒性。结果表明,改性黄原胶的速溶性和粘度有很大提高,0.2%改性黄原胶的速溶性和粘度较对照提高了近3倍,在食品、药品等领域具有潜在的应用价值。     

瓜尔胶与结冷胶复配协效作用规律及粘度流变性研究

瓜尔胶是一种天然高分子化合物,作为增稠剂、稳定剂被广泛使用。瓜尔胶可以与多种多糖胶复配,得到凝胶或高粘度溶液。结冷胶是一种优良的微生物多糖胶,具有极佳的稳定及悬浮效果,在含乳饮料及液态产品中应用广泛。由于其价格较高,溶胶受pH及阳离子浓度影响较大,结冷胶的应用常常受到限制。本文研究了结冷胶-瓜尔胶的配比、pH、离子种类和浓度对瓜尔胶-结冷胶复配体粘度的影响。研究结果表明:复配胶具有协同增粘效果;复配胶粘度在pH值7~11范围内随pH值升高而下降,在pH值为3~7范围内随pH值升高而上升;在盐离子达到一定浓度时,单独的结冷胶无法形成均一体系,而瓜尔胶-结冷胶复配体系能够形成稳定溶胶。     

普鲁兰酶改性瓜尔胶及其与黄原胶复配性能研究

通过红外光谱表征、稳态流动和动态应力扫描法考察了普鲁兰酶对瓜尔胶的脱支效应和改性瓜尔胶与黄原胶的复配性能。结果表明,普鲁兰酶不仅降低了瓜尔胶中半乳糖的含量,也降低了瓜尔胶的分子量及粘度,但未改变瓜尔胶主链的主体结构和糖苷键的构型,也未改变其流变学性质。与天然瓜尔胶-黄原胶复配胶相比,改性瓜尔胶-黄原胶复配胶表现出了较强的屈服应力,能在更高的压力范围内维持较高的弹性模量。随着混合温度升高,复配胶的弹性模量逐渐增大,并且在60℃时达到最大值。研究说明,普鲁兰酶改性瓜尔胶与黄原胶复配具有显著的协同增效效应。     

罗望子胶的流变学性质及凝胶特性研究

罗望子胶的流变学性质和凝胶性能与常见胶种有较大差别。升高温度、提高浓度会增大其表观粘度,这与其单糖组成和多糖结构的特殊性有关。在低浓度下(2%,w/v)罗望子多糖胶水溶液为牛顿流体,而当浓度升高到2.5%(w/v)后呈现非牛顿流体的特性。罗望子多糖胶属于必须有糖存在下才能形成凝胶的氢键结合法。除此之外,罗望子胶粉也可与乙醇通过氢键作用形成高强度凝胶,这种性质是其他多糖胶所不具备的。实验发现,在乙醇体积分数为15%,胶粉浓度1%,85℃恒温搅拌10 min条件下形成的凝胶强度近1 000 Bloom g。在该凝胶体系中适当添加葡萄糖或蔗糖可提高其持水能力。     

新分离Microbacterium sp. XT11菌产黄原胶降解酶生产条件的优化研究

新分离Microbacteriumsp.XT11菌能够合成黄原胶降解酶,将植物病原菌野油菜黄单孢菌分泌的毒素因子黄原胶分解,生成具有激发子和抗微生物活性的黄原胶寡糖。实验确认,黄原胶和酵母浸粉分别是XT11菌生产黄原胶降解酶的最适碳源和氮源,获得最高酶活力的最低碳源和氮源浓度均为0.3%。XT11菌生产黄原胶降解酶的最适条件为:培养温度28℃,培养基起始pH7.0,转速150r/min。     

新分离Microbacterium sp．XT11菌产黄原胶降解酶生产条件的优化研究

新分离Microbacterium sp．XT11菌能够合成黄原胶降解酶,将植物病原菌野油菜黄单孢菌分泌的毒素因子黄原胶分解,生成具有激发子和抗微生物活性的黄原胶寡糖。实验确认,黄原胶和酵母浸粉分别是XT11菌生产黄原胶降解酶的最适碳源和氮源,获得最高酶活力的最低碳源和氮源浓度均为0.3％。XT11菌生产黄原胶降解酶的最适条件为：培养温度28℃,培养基起始pH7.0,转速150r／min。     

野皂荚多糖胶与黄原胶复配增效作用研究

野皂荚多糖胶是一种从豆科皂荚属的灌木或小乔木野皂荚豆分离得到的半乳甘露聚糖胶,按照不同配比、浓度、温度、电解质种类配制野皂荚多糖胶与黄原胶的复配胶液,通过凝胶强度测定仪比较其复配胶液凝胶强度的变化情况。结果表明,野皂荚多糖胶和黄原胶通过分子间缠绕或者分子间次级键的相互作用使其形成凝胶,协同增效凝胶的最优工艺条件为:野皂荚多糖胶与黄原胶复配质量比为6∶4,总胶浓度2%,60℃水浴中加热30min,凝胶强度达到100.5 g/cm~2。加入氯化钾、氯化钠、磷酸二氢钾、氢氧化钾能显著提高复配胶液的凝胶强度。     

淀粉基瓜尔胶可食用膜的研究

以豌豆淀粉为基材、瓜尔胶与CMC为复配增稠剂、甘油为增塑剂制备可食用膜,以膜的感官及耐水性、透油系数、阻氧性为评价指标,对其成膜工艺、配方等进行研究。实验结果表明:当淀粉溶液浓度为8.0%时,增稠剂添加量为2.0%,其中瓜尔胶∶CMC=2∶1;甘油添加量为2.5%时,膜的外观柔韧有光泽;膜的耐水性Ts2400、透油系数为0.97g·mm/m~2·d、阻氧性为0.05%,膜综合性能良好。     

微生物胞外多糖黄原胶的应用与研究进展

黄原胶是由植物病原菌野油菜黄单胞菌产生的一种天然胞外多糖,其结构为重复单元聚合而成的多聚体,单元结构中包含了D-葡萄糖、D-甘露糖和D-葡糖醛酸基团以及O-乙酰和丙酮酸基团。黄原胶具有优良的流变特性,作为增稠剂和稳定剂等被广泛用于食品、药品和化妆品等多个行业。本文主要综述了黄原胶的结构、性质、应用、生物合成、生物合成调控和工业生产条件,为黄原胶的后续研究提供理论基础。     

Potential application of a low-viscosity and high-transparency xanthan gum produced from Xanthomonas campestris CCTCC M2015714 in foods

Xanthan gum is commonly used as a thickener in food industry, while the usage of xanthan gum as a dietary fiber is restricted for its low additive volume. Herein, the potential use of a low-viscosity and high-transparency xanthan gum as a dietary fiber was evaluated in vitro. This new xanthan shows better transparency and faster dissolution rate than most commercial products, and its viscosity increases along with the treatment of freeze–thaw cycles at ?20°C. Moreover, this new xanthan can absorb heavy metals (Pb, Cd, Cu) and retard starch digestion by glucoamylase. In summary, this new xanthan could be potentially used as a dietary fiber or fiber ingredient for preventing and treating diabetes, hyperlipemia, heavy metal poisoning, and cardiovascular diseases effectively.     

黄单胞菌R5产黄原胶的工艺条件研究

本文报道了黄单胞菌（Ｘａｎｔｈｏｍｏｎａｓｃａｍｐｅｓｔｒｉｓ）ＸＣ—８２·５的诱导株Ｒ５发酵生产黄原胶的最适工艺条件。探讨了培养基中不同的碳源、发酵溶氧状况、发酵温度、ｐＨ值、菌龄对产胶水平的影响,向时发现：以菜油替代ＰＰＥ作消泡剂有其独特的优越性;Ｈ２Ｏ２水不能改善溶氧水平。     

黄原胶降解菌BIT-BJ001培养条件的优化

黄原胶在采油工程中有重要的应用,但其难降解性质给采油工程带来很多问题。从塔里木油田胡杨木根部样品中分离得到1株黄原胶降解菌BIT-BJ001,对其发酵条件的研究表明,此黄原胶降解菌最适培养条件为:黄原胶0.3%,酵母粉0.5%,Na+浓度0.8%,Mg2+浓度0.8%,初始pH值为10,温度60℃。菌种BIT-BJ001降解黄原胶的能力与发酵时间、发酵液中还原糖浓度有关,发酵96 h,黄原胶降粘率达到最高,发酵液中还原糖浓度过高,将抑制菌株对黄原胶的降解。     

Guar Gum,Xanthan Gum,and HPMC Can Define Release Mechanisms and Sustain Release of Propranolol Hydrochloride

The objectives were to characterize propranolol hydrochloride-loaded matrix tablets using guar gum, xanthan gum, and hydroxypropylmethylcellulose (HPMC) as rate-retarding polymers. Tablets were prepared by wet granulation using these polymers alone and in combination, and physical properties of the granules and tablets were studied. Drug release was evaluated in simulated gastric and intestinal media. Rugged tablets with appropriate physical properties were obtained. Empirical and semi-empirical models were fit to release data to elucidate release mechanisms. Guar gum alone was unable to control drug release until a 1:3 drug/gum ratio, where the release pattern matched a Higuchi profile. Matrix tablets incorporating HPMC provided near zero-order release over 12 h and erosion was a contributing mechanism. Combinations of HPMC with guar or xanthan gum resulted in a Higuchi release profile, revealing the dominance of the high viscosity gel formed by HPMC. As the single rate-retarding polymer, xanthan gum retarded release over 24 h and the Higuchi model best fit the data. When mixed with guar gum, at 10% or 20% xanthan levels, xanthan gum was unable to control release. However, tablets containing 30% guar gum and 30% xanthan gum behaved as if xanthan gum was the sole rate-retarding gum and drug was released by Fickian diffusion. Release profiles from certain tablets match 12-h literature profiles and the 24-h profile of Inderal^® LA. The results confirm that guar gum, xanthan gum, and HPMC can be used for the successful preparation of sustained release oral propranolol hydrochoride tablets.     

Relationship between the Rheological Properties of Thickener Solutions and Their Velocity through the Pharynx as Measured by the Ultrasonic Pulse Doppler Method

The dependence of the dynamic viscoelastic parameters of carboxymethylcellulose (CMC), xanthan gum, and guar gum solutions on the angular frequency (ω) was compared with that of their viscosity (μ) on the shear rate (γ). In addition, the effect of these rheological properties on the maximum velocity through the pharynx, V _max, as measured by the ultrasonic pulse Doppler method, was investigated. The CMC and guar gum solutions examined were taken as a dilute solution and a true polymer solution, respectively. The xanthan gum solution was taken as a weak gel above 0.5% and a true polymer solution below 0.2%. The maximum velocity, V _max, of the thickener solutions correlated well with μ, the dynamic viscosity η′, and the complex viscosity η^*, especially those measured at γ or ω of 20–30 s^?1 (or rad/s) and above, suggesting that μ, η′, and η^* are suitable indexes for care foods of the liquid type for dysphagic patients.     

Viscoelastic and Thermal Properties of Collagen–Xanthan Gum and Collagen–Maltodextrin Suspensions During Heating and Cooling

The purpose of this work was to investigate the viscoelastic properties of aqueous suspensions of crude collagen powder extracted from bovine hides and nonsubmitted to the hydrolysis reaction that leads to gelatin. The studied variables included the collagen concentration and the addition of xanthan gum or maltodextrin at varied concentrations during heating/cooling of the mixtures. Differential scanning calorimetry thermograms showed that the addition of polysaccharides decreased the endothermic peak areas observed at the denaturation temperature of collagen. The rheological properties of the pure collagen suspensions were highly dependent on concentration: 4% and 6% collagen suspensions presented a great increase in the storage modulus after heating/cooling, whereas for concentrations of 8% and 10% G′ decreased during heating and did not recover its original value after heating/cooling. The frequency sweeps showed that the thermal treatment was responsible by the strengthening of the interactions that formed the polymer network. Addition of 0.1% xanthan gum to collagen suspensions increased the gel strength, especially after heating/cooling of the system, whereas increasing gum concentration to 0.3% resulted in a weaker gel, which could indicate thermodynamic incompatibility between the biopolymers. Mixtures of collagen and maltodextrin resulted in more fluid structures than those obtained with pure collagen at the same collagen concentration and the range of temperatures in which these mixtures behaved as a gel decreased with increasing concentrations of both collagen and maltodextrin, suggesting incompatibilities between the biopolymers.     

Inter- and Intra-Manufacturer Variability in Pharmaceutical Grades and Lots of Xanthan Gum

A pharmaceutical formulation typically contains one or more excipients in addition to the active pharmaceutical ingredient(s). Though excipients have been considered inert components of a formulation, variability in their properties has been shown to affect the performance of drug dosage forms and delivery systems. This study investigates the inter- and intra-manufacturer variability among different NF grades and lots of xanthan gum made by two manufacturers. As many formulators rely on compendial standards to monitor and control the variability of excipients, this study focuses on the adequacy of the NF specifications, in particular the viscosity specification, to discern the variability in solution properties of different pharmaceutical grades and lots of xanthan gum. All the grades and lots in this study were NF grade materials. Xanthan gum solutions were prepared in accordance with NF test methodology and were rheologically evaluated using a rotational rheometer. Both steady shear measurements and small amplitude oscillatory measurements were carried out on 1% w/w xanthan gum solutions. Results showed significant inter- and intra-manufacturer variability among the NF grades and lots of xanthan gum that was not reflected in the NF viscosity test specifications.     

Xanthan production by Xanthomonas campestris using whey permeate medium

Xanthan gum is a polysaccharide that is widely used as stabilizer and thickener with many industrial applications in food industry. Our aim was to estimate the ability of Xanthomonas campestris ATCC 13951 for the production of xanthan gum by using whey as a growth medium, a by-product of dairy industry. X. campestris ATCC 13951 has been studied in batch cultures using a complex medium for the determination of the optimal concentration of glucose, galactose and lactose. In addition, whey was used under various treatment procedures (de-proteinated, partially hydrolyzed by β-lactamase and partially hydrolyzed and de-proteinated) as culture medium, to study the production of xanthan in a 2 l bioreactor with constant stirring and aeration. A production of 28 g/l was obtained when partially hydrolysed β-lactamase was used, which proved to be one of the highest xanthan gum production reported so far. At the same time, an effort has been made for the control and selection of the most appropriate procedure for the preservation of the strain and its use as inoculant in batch cultures, without loss of its viability and its capability of xanthan gum production. The pre-treatment of whey (whey permeate medium hydrolyzed, WPH) was very important for the production of xanthan by the strain X. campestris ATCC 13951 during batch culture conditions in a 2 l bioreactor. Preservation methods such as lyophilization, cryopreservation at various glycerol solution and temperatures have been examined. The results indicated that the best preservation method for the producing strain X. campestris ATCC 13951 was the lyophilization. Taking into account that whey permeate is a low cost by-product of the dairy industry, the production of xanthan achieved under the studied conditions was considered very promising for industrial application.     

基于航空煤油细菌检测的触变显色培养基的制备

利用正交试验测定了三种凝胶在不同配比下的触变性,并添加营养物质葡萄糖、蛋白胨、NaCl和显色剂TTC(四氮唑红),得到具有触变性的显色培养基,可直接用于航空煤油样品的检测。结果表明:黄原胶0.9%、琼脂粉0.4%和卡拉胶0.2%配伍使用,触变效果最好,其中影响因素顺序依次为黄原胶、卡拉胶、琼脂;培养基中TTC的最佳浓度范围为0.0008%～0.002%,能使细菌染成红色,并对菌的生长影响很小。