Sugar-cellulose composites V. The mechanism of fiber strengthening by cell wall incorporation of sugars

The incorporation of sucrose or some other disaccharides (cellobiose, -lactose or trehalose) into the cell wall of pulp fibers increases the tearing resistance of the resultant sugar-containing paper relative to that of its sugar-free counterpart, but only when the fiber is well-refined. Maltose and -lactose do not exhibit this effect. By the use of a high cellulose pulp the increase is shown not to be due to the presence of hemicelluloses. Differential scanning calorimetry indicates that the interaction between the sucrose molecules and the cellulosic fibers changes and becomes more uniform as the fibers are refined. Although the azo dye Congo red bonds strongly with cellulose the analogous reaction with disaccharides and cyclodextrins, established spectrophotometrically, could not be used to predict the physical outcome of the interactions with added disaccharides or cyclodextrins. From a consideration of the stereochemistry of the impregnant disaccharides the augmentation of the fiber strength is attributed to the interlamellar hydrogen bonding of impregnant molecules having hydroxy endgroups in the cis conformation and separated by about 10Å. The incorporation of cyclodextrins further demonstrates that the conformation and the separation distance between the OH groups located in the interlamellar sugar molecule play an important role in strengthening the sugar-impregnated fiber and in augmenting the tearing resistance of sugar-containing papers.     

Hydrolysis of Sucrose by Heterogeneous Catalysts

A kinetic study of the hydrolysis of sucrose by solid catalysts has been carried out using a polarimetric technique. V₂O₅/-Al₂O₃ was selected as appropriate catalyst. At the optimum conditions the activation parameters have been evaluated using the Arrhenius and Eyring plots.     

蔗糖辅助制备大比表面积氧化铝

The preparation of alumina with large surface area, certain phase and porosimetry has always been one of important researches. A new method using much less sucrose (the molar ratio of sucrose to Al^3 =0.5) was developed to prepare γ-Al2O3 with large surface area and high thermal stability. Firstly, ammonium hydroxide was dropped to aqueous solution of aluminum nitrate and sucrose. The resulted precipitate in suspension washeated until a homogeneous gel was ohtained. Then the gel was dehydrated at 110℃ to get a fluffy black precursor. Finally, γ-Al2O3 with A=345m^2/g was prepared by calcining the preeursor at 600℃ for 24h. The precursor and the obtained γ-Al2O3 were characterized by DTA-TG, N2 adsorption-desorption isotherms, XRD and TEM, According to the dispersion behaviors of organic compounds on supports, the related mechanism was discussed.     

一种新的蔗糖水解反应实验设计方案

对蔗糖转化反应动力学实验的实验思路、内容设计进行了重新设计,简化了实验过程,提高了实验可操作性,实际测定结果满意。     

毛细管区带电泳-间接紫外检测法快速测定食品中乳糖、蔗糖、葡萄糖和果糖

建立了毛细管区带电泳-间接紫外检测快速测定食品中乳糖、蔗糖、葡萄糖和果糖的方法。以水或5 mmol/L醋酸为样品提取液,未涂层熔融石英毛细管(30.2 cm(有效长度20 cm)×50 μm)为分离柱,4 mmol/L山梨酸钾+10 mmol/L磷酸钠+30 mmol/L NaOH(pH 12.56)+0.5 mmol/L十六烷基三甲基溴化铵(CTAB)为分离缓冲液,在-8 kV下分离,于254 nm波长下检测,10 min内实现了食品中上述4种糖的同时分离与测定。乳糖、蔗糖、葡萄糖和果糖的检出限(S/N=3)分别为50、75、25和25 mg/L,定量限(S/N=10)分别为150、225、75和75 mg/L,回收率在87.0%~107.0%之间,相对标准偏差在1.2%~4.7%之间。整个实验过程未使用有机溶剂。用该法测定了9种食品样品及1个质控样品,结果表明该法简单、快速、准确,适用于食品中乳糖、蔗糖、葡萄糖和果糖的日常测定。     

蔗糖水解实验数据处理方法的改进

应用Origin数据处理软件,对蔗糖水解反应实验数据的处理提出了一种新方法,在简化实验条件下,无需测反应终了时刻的旋光度,可以快速方便地实现α0,α∞和速率常数k三参数的非线性拟合,提高了实验结果的准确度.     

Two new sucrose esters from the rhizome of Sparganium stoloniferum Buch.-Ham.

Two new sucrose esters, β-D-(1-O-acetyl-3,6-O-trans-diferuloyl)fructofuranosyl-α-D-2′-O-acetylglucopyranoside (1) and β-D-(1-O-acetyl-3-O-cis-feruloyl-6-O-trans-feruloyl)fructofuranosyl-α-D-2′,4′,6′-O-triacetylglucopyranoside (2), together with four known sucrose esters (3–6) have been isolated from the rhizome of Sparganium stoloniferum Buch.-Ham. Their structures were elucidated by physical and chemical evidence and spectral analysis.     

去氢枞酸蔗糖酯的溶剂法合成

松香主要成分是二萜树脂酸(C29H29COOH,含量约为90％),可用作表面活性剂的合成原料。将松香树脂酸与蔗糖进行酯化反应,即可合成松香-蔗糖基非离子表面活性剂。目前关于高级脂肪酸蔗糖酯和松香基表面活性剂的研究有许多报道,但有关松香蔗糖酯的研究报道极少,工艺极不成熟,且都使用未经改性的松香,结构中仍保留两个易氧化的双键,不利于长时间储存和使用。从歧化松香中分离提纯去氢枞酸,     

An integrated strategy of secondary metabolomics and glycomics to investigate multi-component variations in wine-processing of medicinal herbs and functional foods: A case study on Fructus Corni

Fructus Corni (FC), as a promising Chinese medicinal herb, has aroused considerable interest. Generally, FC needs to be processed according to the limited standard policy in China before clinical application, while the investigations on the specific processing methods (such as wine steaming or high-pressure wine steaming) are unclear. A comprehensive metabolomics strategy based on integrated non-targeted metabolomics and targeted glycomics in this paper was implemented to investigate the influences of the different processing technologies such as steaming, wine steaming, high-pressure steaming, high-pressure wine steaming, wine immersion, and wine stir-frying on FC, respectively. UHPLC-Q-TOF-MS/MS was employed for identifying and distinguishing the secondary metabolites. A total of 85 components were identified in all groups. The results of PCA score plots showed that the crude and processed samples had a complete separation, and wine steamed and high-pressure wine steamed samples could be a category, indicating that the two processed products had a similar quality. Multiple chromatography including HPLC (C₁₈)-PDA, HPLC (NH₂)-ELSD, and HPGPC-ELSD was used for determining the molecular weight distributions, the monosaccharide compositions of polysaccharides, and the contents of free monosaccharides and oligosaccharides. The results indicated that the content and composition of saccharides were different in crude and different processed FC. The polysaccharides were composed of fucose, arabinose, galactose, glucose, galacturonic acid, mannose and rhamnose, and the free monosaccharides were composed of fucose, arabinose, galactose, glucose, mannose, rhamnose and fructose in all FC samples. The PCA score plots of the glycomics indicated that the crude and high-pressure wine steamed FC could be a category, showing that the two groups had similar chemical compositions. Ultimately, the simulation processing experiments indicated that the transformation of morroniside, polysaccharides, oligosaccharides, fructose, and glucose to 5-HMF through the reactions of dehydration and deglycosylation was the potential mechanism of enhancing the effects by processing. Conclusionly, the saccharides should be investigated as thoroughly as the secondary metabolites, and the high-pressure wine steamed FC could be an alternative to wine steamed FC.