气相色谱毛细管柱对木糖醇产品的测定

本文提供了一种采用小口径毛细管柱测定木糖醇产品中各组分含量的气相色谱法。该方法采用氢火焰离子化检测器（FID），并用面积归一化法进行计算。实验结果表明该方法分离度高，色谱峰对称，平均回收率在95％以上，相对标准偏差均在1％之内，方法的重现性好。另外，该方法简单、方便、快速、准确，能满足分析检测的要求。     

Hydrogen production from sucrose via aqueous-phase reforming

Commercial sucrose was used to produce hydrogen in a combined approach of hydrogenation and aqueous phase reforming (APR). First a mixture of technical sorbitol/mannitol was produced by hydrogenating an aqueous solution of sucrose in a trickle bed reactor over 5 wt % Ru/C. The produced polyols were treated in a continuous reactor at 498 K and elevated pressure deploying a 2.5 wt % Pt/C catalyst to yield hydrogen. The highest hydrogen selectivity was 62%. No large differences were found when comparing a commercial available sorbitol to the technical sorbitol/mannitol mixture in terms of conversion levels and selectivity to the gas-phase products. This was accompanied by a similar distribution of products retained in the liquid phase. The efficiency of APR when utilizing Pt/C was found to be still insufficient for industrial implementation in terms of hydrogen production. Thus, additional efforts should be made to increase the obtained amounts of hydrogen per mole of converted sugar alcohols.     

山梨醇的生产、应用与开发

概述了山梨醇的生产、应用 ,分析了市场形势 ,认为调整产品结构、提高产品质量、规模经营是我国山梨醇行业的发展方向。     

Isoparaffin production by aqueous phase processing of sorbitol over the Ni/HZSM-5 catalysts: Effect of the calcination temperature of the catalyst

Ni/HZSM-5 catalysts calcined at different temperatures were used in the isoparaffin production by aqueous phase processing of sorbitol and characterized by N₂ physical adsorption, temperature-programmed reduction (H₂-TPR), temperature-programmed desorption of ammonia (NH₃-TPD) and Raman techniques. The effect of calcination temperature of the catalysts on the catalytic performance for the reaction was investigated. The activity test results indicated that the maximal i-C₆H₁₄ selectivity of 45.4% and the total i-C₆H₁₄ and i-C₅H₁₂ yield of 32.3% were obtained over the catalyst calcined at 500 °C, which exhibited the optimum surface area and pore structure with 100% of the reducibility of Ni species on the surface of HZSM-5. In addition, the amount and the strength distribution of acidic surface sites of the catalyst decreased with the increase of calcination temperature at 500 °C above. All these factors result in an increase in the formation of isoparaffin.     

Impact of cosolvents (polyols) on globular protein functionality: Ultrasonic velocity, density, surface tension and solubility study

The objective of this study was to understand how cosolvents influence the molecular and functional properties of globular proteins in aqueous solutions. The ultrasonic velocity, density and adiabatic compressibility of cosolvent solutions (0–50 wt% sorbitol or glycerol) were measured in the absence and presence of a globular protein (1 wt% β-lactoglobulin) at 30 °C. These measurements were used to calculate the partial specific apparent volume and adiabatic compressibility of the protein. The protein's volume decreased and its compressibility increased in the presence of high cosolvent concentrations, which were attributed to changes in the properties of the protein interior and solvation layer. Sorbitol was more effective than glycerol at decreasing the protein volume at high cosolvent concentrations, which may be because glycerol has some surface activity and may therefore accumulate around hydrophobic regions on the protein surface. Our data were used to account for the observation that sorbitol is more effective than glycerol at increasing the thermal stability and self-association of the β-lactoglobulin. A better understanding of the influence of protein–cosolvent–solvent interactions on the functionality of globular proteins may facilitate the design of protein-based products.     

Modulation of thermal stability and heat-induced gelation of β-lactoglobulin by high glycerol and sorbitol levels

The influence of glycerol and sorbitol on the thermal stability and heat-induced gelation of β-lactoglobulin (β-lg) in aqueous solutions was investigated. The thermal stability of β-lg was characterized by measuring the thermal denaturation temperature (T_m) using differential scanning calorimetry, while its gelation properties were characterized by measuring the gelation temperature (T_gel) and final gel rigidity (G^∗) using dynamic shear rheology. All experiments were carried out using aqueous solutions containing 10% (w/w) β-lg, glycerol (0–70% w/w) or sorbitol (0–55% w/w), and 5 mM phosphate buffer (pH 7.0). No salt was added to these solutions so that there was a relatively strong electrostatic repulsion between the protein molecules, which usually prevents gelation. When the cosolvent concentration was increased from 0% to 50%, T_m increased from 74 to 86 °C for sorbitol, but only from 74 to 76 °C for glycerol, which indicated that sorbitol was much more effective at stabilizing the native state of the globular protein than glycerol. Protein solutions containing sorbitol (0–55%) did not form a gel after heating, but those containing glycerol formed gels when the cosolvent concentration exceeded about 10%, with G^∗ increasing with increasing glycerol concentration. We attribute these effects to differences in the preferential interactions of polyols and water with the surfaces of native and heat-denatured proteins, and their influence on the protein–protein collision frequency.     

Synergistic gelation of solutions of isotactic polypropylene and bis-(3,4-dimethyl benzylidene) sorbitol and its use in gel-processing

We report the synergistic, rapid gelation of solutions of isotactic polypropylene (i-PP) and the nucleating agent 1,3:2,4-bis-(3,4-dimethyl benzylidene) sorbitol (DMDBS) in decalin. Cooling to room temperature of a solution comprising, for instance, 3.0 wt% of a moderately high molecular weight i-PP (M_v=1.3×10⁶ g/mol) and as little as 0.0075 wt% DMDBS (0.25 wt% based on the polymer) resulted in the fast formation of highly ductile gels. In reference experiments without DMDBS, often ‘mud-cracked’, brittle polymer films were obtained, and decaline solutions of DMDBS alone at the above concentration did not form macroscopically coherent gels. In the present work we employed this useful occurrence for gel-processing/drawing of i-PP, yielding material with Young's moduli of 35 GPa, tensile strengths of approximately 1 GPa and melting temperatures measured for constrained samples as high as 228 °C.     

Thermomechanical properties of poly(vinyl alcohol) plasticized with varying ratios of sorbitol

The objective of this work is to study the thermal and mechanical properties of films based on blends of poly(vinyl alcohol) (PVA) with different weight percent of sorbitol. Solid-state PVA/sorbitol polymer membranes were prepared by a solution casting method. The characteristic properties of these polymer membranes were examined by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), nanoindentation methods and by Fourier Transform Infrared (FTIR) spectroscopy. It was found that the thermal properties (glass transition, T_g, melting point, T_m and decomposition temperature, T_d) for PVA blends showed a decrease proportional to the sorbitol concentrations. The hardness and elastic modulus obtained from nanoindentation test were also found to decrease with increase in plasticizer concentration. FTIR confirmed the reduction in hydrogen bonding between PVA chains in favour of formation new bonding between the plasticizer and the PVA chains.     

Moisture sorption characteristics of milk<Emphasis Type="Italic"> burfi</Emphasis>, an traditional Indian sweet,using sugar substitutes

Moisture sorption data are useful in choosing suitable packaging material having a desirable water vapour barrier property in addition to determining the stability of the product. The sorption isotherms of milk burfi, one of the important Indian traditional milk-based sweets, using sugar and sugar substitutes were determined. The product was prepared replacing sugar with sorbitol, maltodextrin (MD)+polydextrose (PD), and PD alone, along with aspartame to give an equi-sweetness level compared to sugar. The isotherms followed typical sigmoidal shape, characteristic of sugar-rich products. The curve for burfi with sorbitol shifted to the left compared to that of sugar, whereas for those prepared with MD+PD or PD, the curves are similar to that of burfi made with sugar. Several models were chosen to fit sorption behaviour and the Guggenheim-Anderson-De Boer model showed a better fit compared to other models.     

山梨糖醇类及有机磷酸盐类成核剂对聚丙烯性能的影响

利用力学性能测试、偏光显微镜、光电雾度仪及差热分析仪分别考察了山梨糖醇类成核剂(TM-3)和有机磷酸盐类成核剂(NA-21)对聚丙烯(PP)透明性、结晶性能及力学性能的影响。结果表明:NA-21和TM-3对PP均有明显增透的作用;NA-21比TM-3更能提高PP的结晶温度,而TM-3比NA-21更能提高PP的结晶度;TM-3的加入能明显提高PP的冲击强度,而NA-21的加入能明显提高PP的拉伸强度。