Effects of polyols and sugars on the structure of water in concentrated gelatin gels as studied by low temperature differential scanning calorimetry

 Phase-transition temperatures, glass-transition temperatures, melting temperatures, gel–sol transition temperatures in differential scanning calorimetry heating curves of gelatin solutions with and without various sugars and polyols quenched by liquid nitrogen were studied. Both sugars and polyols added to concentrated gelatin solutions shifted the glass-transition temperatures to lower temperatures, and it was attributed to the increase of unfreezable water which acts as a plasticizer. The mechanisms of the increase in unfreezable water, however, seem to be different for sugars and polyols; sugars increase unfreezable water by increasing the number of junction zones which hold unfreezable water, while polyols by themselves increase the amount of unfreezable water. Received: 9 January 1997 Accepted: 1 July 1997     

Measurement of sugars and starches in foods by a modification of the AOAC total dietary fiber method.

A separation scheme for the determination of sugars and starch in processed food was developed. It is based on AOAC Method 985.29 for total dietary fiber with these modifications: carbohydrate starches are separated into soluble and insoluble fractions before they are hydrolyzed; acetonitrile is used instead of ethanol to separate sugars from enzyme-resistant carbohydrates, proteins, and other macromolecules; and a solid-phase extraction filter is included to remove substances that interfere with high-performance liquid chromatography (HPLC). Recovery studies indicate a > 97% sugar recovery. Twenty foods were analyzed. After enzymatic hydrolysis, fructose, glucose, sucrose, maltose, and lactose were extracted and determined by HPLC using a refractive index detector. Starch content was calculated from the increase in the amount of glucose. The results were compared with values listed on the "Nutrition Facts" panel for that food. The analyzed amounts of sugars and starches were 73-96% of declared values.     

Utilisation d'ylides du phosphore en chimie des sucres VII. Synthèse de sucres ramifiés des types «streptose» et «apiose». Communication préliminaire

A new high-yielding route to branched-chain sugars of the streptose or the apiose type having at the branching point a configuration epimeric with that which would be obtained by the classical synthesis using Grignard reagents is described. The main steps are the preparation of branched-chain unsaturated cyano sugars by reaction of cyanomethylene triphenylphosphorane with keto sugars and the cis-dihydroxylation (KMnO₄) of the so obtained cyano sugars. The cis and the trans isomers of a series of cyanovinylidenic sugars have been separated and the stereodependence of the long-range coupling constants in this class of compounds has been examined.     

Determination of reducing end sugar residues in oligo- and polysaccharides by gas-liquid chromatography

Reducing end sugar residues in maltodextrins and arabinoxylans are determined as alditol acetates by gas-liquid chromatography following reduction, acid hydrolysis and acetylation of the samples. After this conversion to alditol acetates, the reducing end sugars are thus separated from their acetylated aldose counterparts. The method allows to identify individual reducing end sugars quantitatively and is a good alternative for colorimetric reducing sugar assays and 1H-NMR analysis. To demonstrate the advantages of the method, an application in a study of enzymic solubilisation and degradation of water unextractable arabinoxylan from a flour squeegee fraction is described.     

Detection of neutral and aminosugars from glycoproteins and polysaccharides as their alditol acetates

A new method for the preparation and separation of alditol acetates from neutral sugars has been applied to aminosugars. Reduced aminosugars were rapidly acetylated using 1-methylimidazole as the catalyst without removal of borate formed during reduction. The alditol acetates were separated by glass capillary gas chromatography on Silar 10C. The alditol acetates of aminosugars had retention times much longer than those of neutral sugars. However, the alditol acetates of the deamination products of aminosugars had shorter retention times and were resolved from those of neutral sugars. This method was used for the simultaneous detection of neutral and aminosugars in acid hydrolysates of chitin and the glycoproteins, ovalbumin and peroxidase.     

Gas chromatographic separation of sugars by on-column injection on glass capillary columns

Sugars were separated gas chromatographically on short apolar glass capillary columns by using cold, on-column injection (OCI) techniques. After silylation, oligomers up to the hexasaccharides could be efficiently separated in resonable retention times. Response factors of silylated sugars were determined as a function of varying sample amounts and concentrations. The optimum injection amount was found to be 1 μl in heptane as solvent.     

A new acetonitrile-free mobile phase method for LC-ELSD quantification of fructooligosaccharides in onion (Allium cepa L.)

Onion soluble non-structural carbohydrates consist of fructose, glucose and sucrose plus fructooligosaccharides (FOS) with degrees of polymerisation (DP) in the range of 3-19. In onion, sugars and FOS are typically separated using liquid chromatography (LC) with acetonitrile (ACN) as a mobile phase. In recent times, however, the production of ACN has diminished due, in part, to the current worldwide economic recession. A study was therefore undertaken, to find an alternative LC method to quantify sugars and FOS from onion without the need for ACN. Two mobile phases were compared; the first taken from a paper by Vågen and Slimestad (2008) [3] using ACN mobile phase, the second, a newly reported method using ethanol (EtOH). The EtOH mobile phase eluted similar concentrations of all FOS compared to the ACN mobile phase. In addition, limit of detection, limit of quantification and relative standard deviation values were sufficiently and consistently lower for all FOS using the EtOH mobile phase. The drawback of the EtOH mobile phase was mainly the inability to separate all individual sugar peaks, yet FOS could be successfully separated. However, using the same onion extract, a previously established LC method based on an isocratic water mobile phase could be used in a second run to separate sugars. Although the ACN mobile phase method is more convenient, in the current economic climate a method based on inexpensive and plentiful ethanol is a valid alternative and could potentially be applied to other fresh produce types.In addition to the mobile phase solvent, the effect of extraction solvents on sugar and FOS concentration was also investigated. EtOH is still widely used to extract sugars from onion although previous literature has concluded that MeOH is a superior solvent. For this reason, an EtOH-based extraction method was compared with a MeOH-based method to extract both sugars and FOS. The MeOH-based extraction method was more efficacious at extracting sugars and FOS from onion flesh, eluting significantly higher concentrations of glucose, kestose, nystose and DP5-DP8.     

The Rapid Determination of Neutral Sugars in Biological Samples by High-Performance Liquid Chromatography

Abstract

A procedure for the analysis of neutral sugars in biological specimens is described. The method entails acid hydrolysis of the sample to liberate monosaccharides, which are subsequently derivatized with dansyl hydrazine. The sugar-dansyl hydrazones are separated and quantitated by hplc on a 5μ C18 RadialPak column with a gradient of acetonitrile in 10mM ammonium sulfate at pH 7. Fluorescent detection of the derivatized sugars permits 100-fold increased sensitivity compared to previously published glc methods.

This procedure was applied to the neutral sugar analysis of a glycoprotein of known composition (thyroglobulin) and to hard keratin fibers. The latter substance served as a model to critically evaluate the method on a highly resistant biological matrix containing low concentrations of neutral sugars.     

A lipase of the fungus Rhizopus microsporus,UzLT-1 — A glycoprotein

Summary The molecule of the lipase of the fungusRhizopus microsporus UzLT-1 consists of protein and nonprotein moieties. The nonprotein moiety is formed by carbohydrates.The carbohydrate moiety is readily separated from the protein moiety, which suggested a noncovalent bond of the sugars with the protein fraction.Department of Microbiology of the Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 265–267, March–April, 1977.     

高效阴离子交换色谱-脉冲安培检测法分析啤酒和麦汁中的糖

建立了高效阴离子交换色谱-脉冲安培检测(HPAEC-PAD)同时测定单糖、二糖和多种低聚糖的方法。采用水、0.25 mmol/L NaOH溶液和1 mol/L NaAc溶液三元梯度淋洗,在CarboPac PA-100色谱柱上,11种糖在40 min内达到良好分离;采用积分脉冲安培检测方法,无需对样品进行复杂的前处理或衍生反应便可直接检测。11种糖的检出限(S/N=3)在13～88 pg范围内。将该方法用于啤酒和麦汁样品中单糖、二糖及低聚糖的分析取得了很好的结果,样品中的加标回收率为81%～107%。     

Migration of the mobile phase and zones of separated substances in flat-bed chromatography

It is proposed to extend the area of application of circular separation of substances in flat-bed chromatography by a wider use of its intermedial modifications. Equations for calculating the basic parameters of migration of the mobile phase and zones of separated substances are given. The known equations are shown to be particular cases of the ones proposed.     

Determination of mono- and disaccharides by capillary electrophoresis with contactless conductivity detection

The separation and detection of common mono- and disaccharides by capillary electrophoresis (CE) with contactless conductivity detection (CCD) is presented. At high values of pH, the sugars are converted to anionic species that can be separated by CE and indirectly detected by CCD. The main anionic species present in the running electrolytes are hydroxide and phosphate, which have greater mobility than the ionized sugars, and, thus, the indirect detection is possible. The method was applied to analysis of glucose, fructose, and sucrose in soft drinks, isotonic beverages, fruit juice, and sugarcane spirits. Galactose was used as internal standard in all cases. Plate numbers range from ca. 70,700 to 168,200 and the limits of detection from 13 to 31 microM.     

Sphingosine determination at the picomole level using dimethylaminoazobenzene sulphonyl chloride

A sensitive method (lower detection limit 5 picomoles) is proposed for the determination of sphingoid bases liberated from mammalian glycosphingolipids by acid hydrolysis. The azo dye 4-dimethylaminoazobenzene-4'-sulfonyl chloride reacts with the primary amino group of the sphingosine bases, forming a stable derivative. Excess reagent, which is degraded during the derivatization, and free amino sugars as common hydrolysis products of glycosphingolipids are completely separated by reversed-phase high-performance liquid chromatography. This method was applied to the determination of the glycosphingolipid content of mouse spleen and thymus.     

高效液相色谱法在双酶协同作用酶解淀粉制取麦芽低聚糖工艺研究中的应用

介绍了高效液相色谱在双酶协同作用酶解制取麦芽低聚糖工艺研究中的应用。以C18柱为分离柱,水作流动相,利用折光检测器来检测麦芽低聚糖产品中的7种糖,同时评估了补加酶量与麦芽低聚糖中麦芽三糖至六糖含量的关系,并测定了二次确认实验中麦芽低聚糖产品中各糖的含量。     

Comparison of different extraction and detection methods for sugars using amino-bonded phase HPLC

In this study, different methods are compared in order to quantitate individual sugars extracted from apple samples using methanol and water. Glucose, fructose, and sucrose are separated in 20 min using an amino-bonded carbohydrate column and a 75:25 acetonitrile-water mobile phase, followed by UV (190 nm) and refractive index detection. Variations in the sugar profiles are observed using different extraction or detection methods (or both) at a 1.4-mL/min flow rate. The data obtained show differences (p < 0.01) from both extraction or detection methods. The highest contents of free sugars studied occur in samples extracted with water.     

Co-eluent effect in partition chromatography. Rhamnose-xylose separation with strong and weak cation-exchangers in aqueous ethanol

The effect of ethanol in aqueous eluent on the chromatographic separation was studied at 298 K. Two sugars, L-rhamnose and D-xylose, were separated by using strong and weak cation-exchangers as a stationary phase. The ionic form of the resins was Na+ or Ca2+. The separations were carried out with sugar feed concentrations up to 35 wt% and with both low (about 1%) and high (about 10%) feed volume to bed volume ratios. The separation of the sugars was improved by adding ethanol into the eluent. The separation was also significantly enhanced when the weak cation-exchangers with the greatest affinity for water were used instead of strong cation-exchangers as a separation medium for the sugars having different hydrophilicities. The experimental data were successfully explained with a rate-based column model, which accounted for the volume changes of the stationary phase. A thermodynamic sorption model was utilized in column calculations.     

Micropreparative TLC Separation of Large Sample Volumes. Frontal + Elution Chromatography

Abstract

It is demonstrated that mixtures containing few compounds can be applied as wide zones on the edge of the thin layer using a sandwich tank with glass distributor. The mixture is partially separated during application (frontal chromatography) so that subsequent elution accomplishes complete separation. Using 5 × 20 cm plates of silica, 0.5 mm thick, 1 - 3 ml samples were separated easily which permitted elution of 3 - 9 of separated compounds from a single plate.     

Separation behaviors of xylenol isomers by gas chromatography with helps of hydrogen bonding

Summary Xylenol isomers can be resolved on most polyols (sugars or sugar alcohols) and polyethers (polyethylene glycol or polypropylene glycol) with hydrogen-bonding interaction. They are separated on vinical polyols which have more hydroxy hydrogen than tetrol, and even on vicinal triol when its hydroxy hydrogen is acidic (stronger proton donor). The stronger is the hydrogen bonding interaction between xylenols and the liquid phase, the better is the separation of 2,4- and 2,5-xylenol, and the poorer the separation of 2,4-and 2,3-xylenol.     

毛细管电泳法测定市售饮料中糖类物质的研究

毛细管电泳－电化学检测技术（ＣＥ－ＥＣ）,对具有电化学活性的物质的分离检测具有极大的优越性。本文采用ＣＥ－ＥＣ技术,以铜电极为工作电极,在０．１０ｍｏｌ／Ｌ ＮａＯＨ溶液中对１０种市售饮料中的糖类物质的分离检测进行了研究。讨论了ｐＨ值,电泳操作液,分离电压,电极,工作电位等对分离检测的影响,并对１０种饮料中的糖类物质的热量进行了计算。     

Countercurrent ionophoresis. 3. New apparatus for continuous separation according to the countercurrent principle

A new apparatus is described for separation by countercurrent carrier-free electrophoresis. Chemically very similar ions can be separated because of the freely variable sojourn time. It is possible to separate continually mixed ligand complexes of the type [MCl_xBr_6-x]^2- (M = Ir, Os; x = 0, 1 . . . ., 6); the differences in mobilities are below 2%. The separated zones are pure aqueous salt solutions of definite concentrations, which are not contaminated by base electrolyte.