Rheological characteristics of nitrate glycerol ether cellulose gel based on phase separation in ternary system

By non-solvent-induced phase separation, nitrate glycerol ether cellulose (NGEC) gels were formed in ternary NGEC/acetone/ethanol system. The rheological behaviors of NGEC gels were investigated using dynamic rheological measurements. The final compositions and morphologies of NGEC gels were influenced by the initial solvent/non-solvent (acetone/ethanol) ratios and NGEC concentrations. In addition, the effect of initial acetone/ethanol ratios on the characteristics of NGEC gels is different from the effect of NGEC concentrations. The critical strain of NGEC gels decreased almost with increasing NGEC concentration of gels by increasing initial acetone ratio, but it increased with increasing NGEC concentration of gels by increasing NGEC concentration beyond a certain concentration in 2/3 (w/w) acetone/ethanol solution. For all gels, the storage modulus (G′) and loss modulus (G′′) of NGEC gels rapidly increased with increasing NGEC concentration of gels. In addition, the curves for G′ and G′′ were temperature sensitive throughout the entire temperature sweep, which implied that the interactions between NGEC/solvent could be disrupted upon heating to higher temperatures.     

Influence of Temperature,Concentration, and Gas/Liquid Ratios on the Gas-Mobility Reduction of Foams in Porous Media

The gas-mobility reduction capability of sodium dodecylbenzene sulfonate foams was studied in sandpacks as a function of temperature at different surfactant concentrations and gas/liquid ratios. Increasing the temperature decreased the gas mobility at a given surfactant concentration and gas/liquid ratio. At any given temperature, the gas-mobility reduction was not increased beyond a certain limit with increasing surfactant concentration. While increasing the gas/liquid ratio improved the gas-mobility reduction at 20°C, at higher temperatures the reduction capability decreased after reaching a maximum at a gas/liquid ratio of 9. All the foams became weak at temperatures of 150°C and higher.     

PROPERTIES OF THERMO-MOLDED GLUTEN/GLYCEROL/SILICA COMPOSITES

Environmentally friendly thermosetting composites were successfully prepared by conventional blending wheat gluten as matrix,glycerol as plasticizer and silica as filler followed by thermo-molding of the mixture at 120℃.The strong interfacial interaction between silica particles and gluten proteins leaded to an increase in storage modulus and a decrease in loss factor as revealed by dynamic mechanical analysis.The moisture absorption and elongation at break decrease while Young's modulus and tensile stre...     

Effects of Propionic Acid and pH on Ethanol Fermentation by Saccharomyces cerevisiae in Cassava Mash

The effects of propionic acid on ethanol and glycerol production by Saccharomyces cerevisiae in cassava mash were examined along with the influence of pH (4.0, 5.0, and 6.0) and of dissolved solids content (22%, 25%, and 27%). Inhibition by propionic acid increased as solids content increased and medium pH declined. Complete inhibition of ethanol fermentation was observed in mashes at pH 4.0 (60 mM propionic acid for 22% solids and 45 mM for 25% and 27%). Glycerol production linearly decreased with increased undissociated propionic acid concentration in all mashes at all pH levels, which partly contributed to increased final ethanol production when propionic acid concentration in mashes was low (≤ 30 mM).     

Characterization of a Recombinant Flocculent Saccharomyces cerevisiae Strain that Co-ferments Glucose and Xylose: I. Influence of the Ratio of Glucose/Xylose on Ethanol Production

Glucose/xylose mixtures (90 g/L total sugar) were evaluated for their effect on ethanol fermentation by a recombinant flocculent Saccharomyces cerevisiae, MA-R4. Glucose was utilized faster than xylose at any ratio of glucose/xylose, although MA-R4 can simultaneously co-ferment both sugars. A high percentage of glucose can increase cell biomass production and therefore increase the rate of glucose utilization (1.224 g glucose/g biomass/h maximum) and ethanol formation (0.493 g ethanol/g biomass/h maximum). However, the best ratio of glucose/xylose for the highest xylose consumption rate (0.209 g xylose/g biomass/h) was 2:3. Ethanol concentration and yield increased and by-product (xylitol, glycerol, and acetic acid) concentration decreased as the proportion of glucose increased. The maximum ethanol concentration was 41.6 and 21.9 g/L after 72 h of fermentation with 90 g/L glucose and 90 g/L xylose, respectively, while the ethanol yield was 0.454 and 0.335 g/g in 90 g/L glucose and 90 g/L xylose media, respectively. High ethanol yield when a high percentage of glucose is available is likely due to decreased production of by-products, such as glycerol and acetic acid. These results suggest that ethanol selectivity is increased when a higher proportion of glucose is available and reduced when a higher proportion of xylose is available.     

Electrospinning of zein/chitosan composite fibrous membranes

<正>Zein/chitosan composite fibrous membranes were fabricated from aqueous ethanol solutions by electrospinning. Poly(vinyl pyrrolidone)(PVP) was introduced to facilitate the electrospinning process of zein/chitosan composites.The asspun zein/chitosan/PVP composite fibrous membranes were characterized by scanning electron microscopy(SEM) and tensile tests.SEM images indicated that increasing zein and PVP concentrations led to an increase in average diameters of the composite fibers.In order to improve stability in wet stage and mechanical properties,the composite fibrous membranes were crosslinked by hexamethylene diisocyanate(HDI).The crosslinked composite fibrous membranes showed slight morphological change after immersion in water for 24 h.Mechanical tests revealed that tensile strength and elongation at break of the composite fibrous membranes were increased after crosslinking,whereas Young's modulus was decreased.     

SDS/正癸醇/甘油与SDS/正癸醇/甲酰胺液晶结构

以极性有机物为溶剂制备展状液晶已经引起重视,但关于极性有机溶剂对层状液晶结构和稳定性影响的研究还很不够.我们曾以~2H NMR测量研究了以甲酰胺代替甘油为溶剂,对非水层状液晶SDS/C_(10)H_(21)OH/溶剂体系稳定性的影响.本文则以小角X射线衍射测量,研究以甲酰胺代替甘油后,对层状液晶SDS/C_(21)H_(21)OH/溶剂体系结构的影响。     

Effects of glycerol and sorbitol on the thermal dependence of the lysis of human erythrocytes by ethanol

In this work, the effects of 1 mol/L glycerol or sorbitol on the thermal dependence (27-47 degrees C) of the lysis of human erythrocytes by ethanol in saline solution (0.154 mol/L NaCl) have been evaluated. Lysis was monitored by measurement of the absorbance at 540 nm. Ethanol produced either lysis or protection against lysis depending on the conditions. These antagonistic effects are attributed to the existence of expanded (R) and compacted (T) erythrocytes, present under conditions of low and high osmolarity, respectively. The transitions of lysis of the R state and formation and lysis of the T state were all found to be sigmoidally defined. The ethanol concentration at the midpoint of the lysis transition of the R state (D(50R)) was found to decrease with increasing temperature and osmolarity. In the presence of glycerol or sorbitol, an increase in temperature led to smaller decreases in D(50R) and osmotic protection against lysis. The ethanol concentration at the midpoint of formation (S(50T)) and lysis (D(50T)) of the T state also decreased with increasing temperature and osmolarity. Lysis of R state erythrocytes is determined by the chaotropic action of ethanol, but the formation and lysis of T state erythrocytes are determined by osmotic pressure effects.     

Stable aqueous film coating dispersion of zein

The effects of plasticizers, pH, and electrolytes on film formation and physical stability of aqueous film coating dispersions (pseudolatexes) of zein were evaluated. The influence of plasticizer on film formation mechanism and minimum film-formation temperature (MFT) were monitored by means of hot stage microscopy (HSM). Furthermore, the effects of pH and electrolytes on the short-term physical stability of pseudolatexes were investigated by measuring relative absorbance, zeta potential, and particle size of the dispersions. With aqueous coating dispersions of zein, stages of film formation were identified. The dispersions plasticized with 20% (w/w) PEG 400 or glycerol formed mechanically strong and flexible films with the lowest glass transition temperature (T(g)). Physical stability of the aqueous zein dispersions was dependent on both pH and electrolyte content. At a pH ranging from 3 to 4, the aqueous dispersions of zein were stable for at least 2 months exhibiting the highest values for zeta potential, the smallest particle size, and a low volume of aggregates. The stable dispersion could be obtained containing a lower concentration of electrolytes (e.g., 10(-5) M). The physical stability of aqueous zein dispersions can be determined by the combined measurements of relative absorbance, zeta potential, and particle size.     

分散共聚法制备窄分布P(St-co-nBA)微球

用分散共聚法制得窄分布苯乙烯(St)和丙烯酸正丁酯(nBA)的共聚物微球.采用1H-NMR、DSC、FTIR、SEM、LS等对共聚物的结构、形态、性能进行表征,考察了初始单体配比、温度、稳定剂浓度、分散介质极性、引发剂对微球粒径、粒径分布及转化率的影响.实验结果表明,初始单体比nBA/St增大,微球粒径增大,分布变宽,...     

高效液相色谱法同时分析低浓度的葡萄糖、乙醇和甘油

 用高效液相色谱法同时分析、示差折光检测器检测酿酒酵母发酵液中的葡萄糖、乙醇及甘油。方法快速、灵敏、操作方便。同时利用高效液相色谱法对酿酒酵母细胞群体发酵初期的代谢行为进行了初步研究。     

Edible wheat gluten (WG) protein films

Commercial wheat gluten (WG) films, hard wheat gluten films and soft wheat gluten films, plasticized with glycerol have been cast from water–ethanol solutions. The effect of aging on various film properties has been investigated. The films were aged for about 6 months at 50% relative humidity and ~25 °C, and the mechanical (tensile strength and the percentage of elongation at break (E _b)), thermal (TG and DSC) and Attenuated Total Reflectance (ATR)-FTIR spectral properties have been studied. Changes in the protein structure were determined by ATR-FTIR spectroscopy. Films from soft WG exhibited the highest E _b (508%) and the highest TS (6.33 MPa). The TG analysis results show that the moisture content in all three kinds of WG protein films is about 5%. The absence of the glycerol phase transition in DSC curves implies that there is no separate phase containing glycerol in the WG protein-glycerol films with 40% glycerol.     

Influence of Glycerol Content on Properties of Wheat Gluten/Hydroxyethyl Cellulose Biocomposites

Environmentally friendly biocomposites were prepared by blending wheat gluten（WG）as a matrix, hydroxyethyl cellulose（HEC）as a filler,and glycerol as a plasticizer,followed by thermo-molding of the mixture at 120°C for crosslinking the matrix.Moisture absorption,tensile properties,dynamic mechanical analysis,and dynamic rheology were evaluated in relation to the glycerol content.Tensile strength and modulus drop dramatically with increasing glycerol content,which is accompanied by significant depression in the glass transition temperature and improvement in the extensibility of the biocomposites.     

Influence of sample extraction solutions on the detection of wheat proteins by mass spectrometry

Routinely used methods for the detection of gluten mostly use denaturing agents and high salt concentrations to increase the extractability of the gluten fraction. These work well in combination with ELISA methods, but may have a negative effect on MS methods due to their influence on the ionization of the analyte leading to a significant reduction of signal intensities. A newly developed HPLC/MS/MS method was used to assess this influence. Four different extraction buffers were compared: 70% ethanol, TRIS-HCl, TRIS-HCl with dithiothreitol, and a commercially available cocktail solution. Unprocessed and processed wheat samples were analyzed. When analyzing unprocessed samples, a negative effect on ionization could be observed. Considering extraction capabilities and signal intensities, TRIS-HCl seemed to be the most suitable buffer in combination with the MS method. To assess whether the method was capable of detecting hidden wheat protein in different kinds of food, different food samples containing 0 to 34000 microg/g gluten were analyzed using the TRIS-HCI extraction buffer.     

Production of fuel alcohol from wheat by VHG technology

Very high gravity (VHG) wheat mashes containing more than 300 g of dissolved solids per liter were prepared and fermented with active dry yeast at 20, 25, 30, and 35°C with and without yeast extract as nutrient supplement. At 20°C, mashes with 38% (w/v) dissolved solids end-fermented without any nutrient supplementation and maximum ethanol yields of 23.8% (v/v) were obtained. With increasing temperatures, the sugar consumption decreased. Addition of yeast extract stimulated the rate of fermentation at all temperatures, but did not increase the total amount of sugar consumed. The stimulatory effect of yeast extract on cell multiplication decreased with increasing sugar concentration, and virtually no difference in cell number was observed between yeast extract-supplemented and unsupplemented mashes at sugar concentrations above 33% (w/v). The fermentative capacity of the yeast (expressed as maximum specific rate of sugar consumption) remained the same at all sugar concentrations in unsupplemented mashes, but decreased in yeast extract-supplemented mashes at sugar concentrations below 33% (w/v). When the sugar concentration was above 33% sugar (w/v), the fermentative capacity in yeast extract-supplemented mashes was greater than that observed in unsupplemented samples.     

百合皂甙多糖的连续提取工艺研究

皂甙和多糖是药用百合的两个主要有效成份。文章用正交实验法对百合皂甙多糖的提取工艺进行了研究。优选出简便可靠且适合工业化生产的连续提取百合皂甙多糖的工艺。百合皂甙的最佳提取工艺条件是:温度为70℃,乙醇浓度为80%,固液比例为1:6,提取时间3h,提取次数3次。多糖的最佳提取工艺条件是:温度为95℃,固液比例为1:10,提取时间3h,提取次数2次。用AB-8大孔吸附树脂分离、乙醚-丙酮分步沉淀得到纯百合皂甙。     

Wheat gluten films obtained by compression molding

Edible films based on plasticized wheat gluten protein were prepared by intensive mixing followed by compression molding. The effects of water and glycerol, which were selected as plasticizers for the wheat gluten, as well as the processing conditions (mixing time and molding temperature) on the physical and mechanical properties of the films were evaluated. The resulting films were characterized in terms of moisture sorption, total soluble matter, water vapor permeability, dynamic mechanical and tensile properties. It was found that plasticizer type and concentration had a dominating effect on mechanical properties and WVP, while other physical properties remain almost non-affected. Moreover, the effect of the added plasticizer (glycerol) on the film properties strongly depends on natural presence of water in commercial gluten (9% as is). On the other hand, the pressing temperature affected the final properties of the films more than the mixing time because the former influences the final cross-linking degree of the protein network. Processing temperatures higher than 100 °C led to darker films that would be discarded by consumers if they were used as food packaging.     

百合皂苷的提取﹑纯化及其鉴定

用正交实验法对百合总皂甙的提取工艺中温度、乙醇浓度、提取系统中固液比例、回流时间和提取次数5个因素进行研究,优选出简便可靠、且适合工业化生产的百合总皂甙的提取工艺。其最佳提取工艺条件是:温度为70℃,乙醇浓度为80%,固液比例为1∶6,提取时间3h,提取次数3次。用AB-8大孔吸附树脂分离、乙醚-丙酮分步沉淀得到纯百合皂苷。通过TCL薄层层析检测和红外光谱对其结构进行了初步鉴定。     

Effect of Zeolite NaY and Ca-Montmorillonite on Ethanol Production Using Synthetic Molasses

The influence of Ca-Montmorillonite (Ca-MNT) and zeolite NaY addition on ethanol production from synthetic molasses by S. cerevisiae 251 TP(3-2) was studied by the measurement of biomass concentrations and metal ion concentration with respect to fermentation time. Addition of 5 g/L Ca-MNT and 10 g/L zeolite NaY resulted in an increase in both ethanol concentration and ethanol production rate. This increase was 24 and 40% for ethanol concentration and 65 and 87% for production rate, respectively. From the ion analyses, it was observed that the NaY added to the medium decreased the toxic concentration of zinc, manganese, and iron cations and acted also as a pH regulator. Ca-MNT added to the medium decreased the concentration of Na⁺ ions, which is known to have a toxic effect on glycolysis and cell concentration. These effects caused improvement in the ethanol production rate.     

Structural Properties of Glass-Forming Ethanol and Glycerol From O–H Vibrational Spectra

The O–H stretching vibrations of hydrogen-bonded glass formers (ethanol and glycerol) are studied by Raman scattering in a temperature range where the liquid state changes from low-viscous to solid. Several characteristic bands exhibiting different temperature behavior can be distinguished in the O–H vibrational spectrum of ethanol. The appearance of an additional band on cooling ethanol below 220 K is related to the appearance of locally favored structures. No notable manifestations of these features are detected in the spectra of glycerol.