发酵因素对黄原胶丙酮酸含量的影响

本文报道了发酵因素对黄原胶丙酮酸含量的影响。研究结果表明,碳源、氮原、无机盐和摇瓶振荡培养速度是影响黄原胶丙酮酸含量的极显著因索,接种量是不显著因素。经正交设计统计学分析,产生高丙酮酸含量黄原胶的摇瓶发酵培养基是:蔗糖2％、玉米淀粉2％、豆饼粉0.5％、K2HPO_40.5％、Mg—SO_4·7H_2O 0.02％、pH7.0,摇瓶发酵的接种量是2％,摇瓶振荡培养速度是240rpm。     

微粒助留助滤体系对烟草薄片浆料助留助滤性能的影响

在造纸法烟草薄片的生产中,利用食品安全级的阳离子壳聚糖和瓜尔胶与膨润土和胶体二氧化硅组成二元微粒助留助滤体系,研究其对烟草浆料助留助滤性能的影响。研究结果表明：使用壳聚糖／膨润土或瓜尔胶／膨润土组成的二元微粒助留助滤体系能明显改善烟草浆料的留着率和滤水性能。壳聚糖（用量为0．1％）与膨润土（用量为0．4％）所组成的二元微粒体系与只添加0．1％的壳聚糖相比,烟草浆料单程留着率和填料留着率分别提高14％和12％,20s内滤水量提高200g。     

桃果实贮藏期间病原真菌的ITS rDNA序列分析与鉴定

目的:对桃果实采后病原菌进行分离与鉴定.方法:采用转接法分离桃果实采后病原真菌,经形态学观察和核糖体rDNA ITS(Internal transcribed spacer)区序列分析,对相关病原菌进行分类鉴定.结果:从采后贮藏过程中发生病害的桃果实分离到2株病原菌,经鉴定分别为美澳型核果链核盘菌(Monilinia fructicola)和葡萄座腔菌(Botryosphaeria dothidea).结论:通过对ITS rDNA序列的相关分析,对分离自采后贮藏果实中的病原真菌进行有效的分类鉴定.     

钙处理对中华寿桃采后生理的影响

研究钙处理对中华寿桃果实采后生理的影响.试验结果表明:1.5%的CaCl2溶液处理能够显著降低中华寿桃果实采后的呼吸强度和乙烯释放,延缓桃果硬度和可溶性固形物含量的下降,抑制细胞膜渗透率和出汁率的增加,较好地保持中华寿桃果实的贮藏品质.     

黄原胶特性及生产

该文结合有关黄原胶研究报道,介绍黄原胶分子结构及特性;从黄原胶发酵工艺、反应器等方面讨论目前黄原胶生产研究方向和热点,讨论碳源、氮源对黄原胶产量影响,从发酵动力学角度讨论影响黄原胶发酵产量因素;并对目前国内外黄原胶生产状况进行分析。     

Effect of temperature and cross-linking density on rheology of chemical cross-linked guar gum at the gel point

The evolution of viscoelasticity within a solution of guar gum (GG) in the presence of an excess of cross-linker (glutaraldehyde, Ga) has been monitored, at different temperatures (7, 15, 25 and 37 °C), evaluating the sol–gel transition by means of dynamic mechanical experiments. Furthermore, at 25 °C, the samples were characterized as a function of the different amounts of cross-linker. The gelation time of the systems, evaluated with the loss tangent, decreased with increasing temperature and, at a fixed temperature (25 °C), decreased with increasing cross-linker concentration. At the gel point a power-law frequency dependence of the dynamic storage modulus (G′≈ωⁿ) and loss modulus (G″≈ωⁿ) was observed. The value of n, evaluated according to three different methods (n_slope, considering the parallelism of the two moduli, n_tan, from the frequency-independence of tan δ, and from the crossing point between the apparent exponents of G′ and G″, n_app), decreases with increasing cross-linking densities and with increasing temperature. The fractal dimension (d_f) was determined for the incipient GG/Ga hydrogels. The value of d_f increases with increasing cross-linker concentration and decreases with increasing temperature. This trend of d_f suggests a more “tight” structure of the network at higher cross-linking densities and at lower temperatures. The activation energy (E_a) of the chemical reaction between GG and Ga was estimated: the experimental value was close to those obtained in the case of similar chemical reactions among polymers and different kinds of cross-linkers.     

沙蒿籽胶的流变学性质研究

研究了沙蒿籽胶的静态流变学特性和动态流变学特性。静态流变学表明:沙蒿籽胶溶液是触变性流体,其表观粘度随质量分数的增加而增加,且随剪切速率变化的影响符合Herschel-Bulkey模型;温度、pH值等对沙蒿籽胶溶液的表观粘度影响较小;盐的加入能改变沙蒿籽胶溶液的粘度。动态流变学特性表明:沙蒿籽胶溶液显示弱凝胶特性。     

瓜尔胶用于浆内增强及助留助滤

实验研究了瓜尔胶在浆内增强作用及助留助滤作用，对瓜尔胶和阳离子淀粉混合使用做了对比。结果表明，加入瓜尔胶后能提高强度、留着率，改善滤水效果。瓜尔胶与阳离子淀粉混合使用，增强、助留助滤作用更明显。     

瓜儿胶改性及其衍生物在造纸工业的应用

介绍了瓜儿胶的羟烷基及阳离子醚化改性技术,瓜儿胶与丙烯酰胺、丙烯氰等乙烯基单体的接枝共聚改性,总结了各种引发体系下接枝率,接枝效率等指标的优化条件。论述了瓜儿胶衍生物在造纸湿部作为助留助滤剂、增强剂的应用,并指出今后的发展前景。     

Transport of Gellan Gum Microbeads in Soil Columns of Various Grain Size Distributions

The transport of gellan gum microbeads as potential cell carriers was investigated in horizontal columns packed with different grain size classes of gravel (2–16 mm) and sand (0.25–2 mm). A suspension of microbeads was pulsed into each column for 6 h, followed by injection of water for 42 h. In general, the total amount of microbeads travelling across a given section of the column increased with injection time but decreased towards the column outlet, varying as a direct function of grain size. The results of this study demonstrate the feasibility of the transport of gellan gum microbeads through medium sand to medium gravel across distances up to 110 cm.