Complex Mixture Of Sugars Research Articles

Fusarium oxysporum: Status in Bioethanol Production

Fermentation of lignocellulosic materials to ethanol and other solvents provides an alternative way of treating wastes and producing chemical feedstocks and fuel additives. Considerable efforts have been made in past 10 years to improve the process based on lignocellulosic biomass and hydrolysate that contains a complex mixture of sugars, decomposition products of sugars, and sometimes the inhibitory levels of soluble lignin. Despite the relative abundance of D-xylose in crop and forest residues it has not been found efficiently fermentable by most of the microorganisms. Recent research has revealed that D-xylose may be fermented to ethanol and organic acids. Recently, several strains of Fusarium oxysporum have been found to have potential for converting not only D-xylose, but also cellulose to ethanol in a one-step process. Distinguishing features of F. oxysporum for ethanol production in comparison to other organisms are identified. These include the advantage of in situ cellulase production and cellulose fermentation, pentose fermentation, and the tolerance of sugars and ethanol. The main disadvantage is the slow conversion rate when compared with yeast.

The Favored Formation of Threo-3-Pentulose in the Formose Reaction

ABSTRACT The “formose reaction” is the generic name for the base-catalyzed condensation of formaldehyde to give “formose” which is a complex mixture of sugars, alditols, organic acids, etc.2 Increasing attention has been recently given to this reaction because of its possible importance in the manufacture of edible carbohydrates from a simple material and its possible role in the prebiotic synthesis of carbohydrates.3 In our recent study4 on the reaction catalyzed by triethylamine (TEA) and thiamine HCl in N,N-dimethylformamide (DMF)-water mixed solvent, the formation of 3-pentulose (GP-11-1 corresponding to GLC peak number 11-1) was suggested. P. Decker et al.5 also reported that at the end of formaldehyde consumption the concentration of 3-pentuloses became smaller because of their higher reactivity (these carbohydrates cannot form stable furanoses or pyranoses) compared to tetroses, pentoses, and hexoses. Although the isolation of 3-pentuloses was not described in that report,5 erythro-3-pentulose and threo-3-pentulose in a formose were identified by comparison of GLC retention times and mass spectra with those of authentic samples.

The equiratio taste mixture model successfully predicts the sensory response to the sweetness intensity of complex mixtures of sugars and sugar alcohols.

The equiratio taste mixture model was originally developed for the prediction of psychophysical power functions of equiratio mixtures of substances that have a similar taste and that also exhibit mutual cross adaptation. Earlier studies have shown that the model is valid for mixtures of sugars and/or sugar alcohols. Two experiments are reported in which it is questioned whether the psychophysical functions of mixtures of higher physical complexity can be predicted by the model. In the first experiment the psychophysical power functions of binary and quaternary equiratio mixture types were determined experimentally and compared to those predicted by the generalized model. In the second, similar, experiment quaternary and eight-component mixture types were examined. The method of magnitude estimation, in combination with the sip and spit procedure, was used. The functions predicted by the model were almost identical to the functions established on the basis of the experimental data. These results reconfirm that the gustatory modality operates like an 'averaging' system when processing this kind of mixture. It is argued that for other kind of mixtures the model will predict incorrectly. The status of the equiratio mixture model is discussed.

Liquid Chromatography of Sugars on Diol Columns. Detection with Cuprammonium Reagent

Abstract Post column reaction of sugars with cuprammonium reagent is discussed. Formation of the complex involves two molecules of carbohydrate and one molecule of Cu(NH3)4(H2O)2 2+ with the result of a shift towards longer wavelength in UV spectrum. 1 nanomole of fructose is detected, the reaction is simple, fast allowing very short reaction coil which does not increase band broadening it thus matches most of the requirements in the analysis of sugars in food products. Diol bonded silica is much less retentive than amino bonded silica and cannot compete in the separation of complex mixtures of sugars but is well suited for the analysis of one reducing sugar as important losses occur with NH, columns. Diol phase is well adapted to the separation of oligosaccharides. The use of HPLC as a means of determining all types of sugars has greatly increased for the last years. Many types of packings (bare silica, ion exchange with Na+ or Ca2+, alkyl or amino bonded silica) are available and have been advocated (1)...

A Selective Synthesis of 3,3-Di-C-(hydroxymethyl)-3-deoxy-furanorono-1,4-lactone in the Formose Reaction

Abstract The formose reaction, by which a complex mixture of sugars and sugar alcohols (the so-called formose) are produced by the base-catalyzed condensation of formaldehyde, has received much attention in connection with the prebiotic synthesis of carbohydrates2 and the microbial utilization of formose.3–5 Formose, however, has not been useful yet, because of the complexity of this product mixture (Fig. 1a). Therefore, it seemed desirable to make the reaction more selective.

Mass spectrometry in food analysis.

Foods are complex mixtures of sugars, oils, proteins, vitamins, polyphenols, etc., which develop a myriad of flavour and aroma constituents during ripening and cooking. Agricultural and technological residues from pesticides and additives further complicate these mixtures where quantities of individual compounds range from several per cent to sub-part per billion levels. Mass spectrometry has proved an excellent tool for characterization and estimation of food components because of its high sensitivity and specificity. Gas chromatography mass spectrometry undoubtedly provided the major opening for mass spectrometry in food applications: natural volatiles and derivatized polar isolates were readily analysed even in mixtures with over 100 constituents. Organoleptically important minor components were identified in many foods and were monitored as a function of ripeness or cooking conditions. With computer treatment and library facilities, much gas chromatographic mass spectrometric work in flavour and aroma chemistry is now routine. Selected ion monitoring and multi-peak monitoring are used with electron impact, chemical ionization or negative chemical ionization to quantify pesticides, nitrosamines, mycotoxins and other contaminants in part per billion amounts. Isotope mass spectrometry can distinguish natural food flavourings from synthetic chemical equivalents, and can thus be used to detect adulteration. For the future there is room for applications of chemical ionization and negative chemical ionization in trace identification, for liquid chromatography mass spectrometry and collision activated decomposition in mixture analysis, and for new ionization techniques like desorption chemical ionization, laser desorption and fast atom bombardment in the investigation of highly polar solids and biopolymers: polypeptides, polysaccharides, polyphenols, nucleosides and nucleotides, etc. However, the adoption of new mass spectrometric methods by food analysts will ultimately depend on their ease of operation.

Estimation of neutral sugars and sugar alcohols in biological fluids by gas-liquid chromatography

Gas-liquid chromatographic procedures for measuring sugar and polyol concentrations in biological fluids are reviewed. Such methods require the preparations of derivatives such as methyl ethers, trimethylsilyl ethers or acetyl esters. Prior to derivatisation samples must be deproteinised and dried. Complex mixtures of sugars and sugar alcohols may be resolved. Quantitative analyses are precise, sensitive and linear. If internal standardisation is used recoveries approaching 100% are obtained.

The use of temperature to simplify formose sugar composition

Form ose reaction, the Ca(OH)2 catalyzed condensation of HCHO to a complex mixture of sugars, does not lose its autocatalytic nature at 98°C. The induction period is 15 sec, and then, at 18% total HCHO conversion, there was a period of approximately 3 sec duration in which the reaction had produced C6 sugars at 84.3 wt.% selectivity. Glucose amounted to 90% of those sugars, and no branched sugars were detected. Conversion was complete within 3 min. The simple nature of the product was lost at lower temperatures or higher conversions.

The sugars of honey--a review.

AbstractSurveys of floral honey composition have established that the three major components are fructose, glucose, and water, averaging 38.2, 31.3 and 17.2%, respectively. Glucose and fructose are the only monosaccharides in honey and it is these sugars, combined in various forms, that comprise the di‐ and trisaccharide fractions of floral honey. Several laboratories, utilising various chemical and physical methods, have been responsible for the isolation and characterisation of ten disaccharides, ten trisaccharides, and two higher sugars from floral honey. Several of these occur only rarely in nature, and the trisaccharide erlose, produced by the action of honeybee invertase on sucrose, was first discovered as a component of honey. Honeydew honey is produced by the honeybee from honeydew deposits left by various hemipterous insects on their host plant. Honeydew contains a more complex mixture of sugars than does nectar, and honeydew honey is appreciably higher in reducing disaccharides and higher sugars than is floral honey. The trisaccharide melizitose, not found in floral honey, is often present in levels exceeding 10% in honeydew honey. The precipitation of glucose from honey, termed granulation, is often technologically undesirable as it is sometimes followed by fermentation. Indices such as the glucose/water ratio have been used to predict granulation tendency. Small amounts of hydroxymethylfurfural (HMF) occur naturally in honey, resulting from the acid catalysed dehydration of the hexoses, particularly fructose. High levels of HMF suggest adulteration of honey with acid inverted invert syrup and several methods are available for its determination. The conversion of nectar and honeydew to the complex array of honey sugars by the honeybee involves a variety of chemical and biochemical processes, some of which are now understood, while others remain to be elucidated.

Thin-layer chromatographic detection of glycolaldehyde using a fluorescence reaction with o-aminodiphenyl

It was found that glycolaldehyde reacted with o-aminodiphenyl in the presence of sulphuric acid on silica gel thin-layer chromatograms to form a compound which, on UV irradiation, gave an intense bluish white fluorescence. This reaction was used to detect glycolaldehyde in complex mixtures of sugars. The reversible interconversion of the monomer and dimer of glycolaldehyde is discussed.

Thin-layer chromatographic analysis of sugar mixtures

Some general remarks are made concerning the difficulties experienced in the quantitative determination of the composition of complex sugar mixtures in solution. The application of thin-layer chromatography to this analytical problem is discussed. A technique for obtaining a satisfactory separation of nine to ten sugars has been worked out. Methods of determining reducing sugars and keto-sugars in amounts of 0 to 100 μg are mentioned, as well as a technique for removing the sugar-containing area from the thin-layer plate. Figures illustrating the quantitative aspects of the method are given.

Anogeissus leiocarpus gum. Part IV. Exterior chains of leiocarpan A

Methylation of leiocarpan A followed by reduction and hydrolysis furnishes a complex mixture of sugars including 2,3,4-tri-O-methyl-D-xylose, 2,3,5-tri-, 2,3-, and 2,5-di-O-methyl-L-arabinose, 2,3,4,6-tetra-, 2,4,6-tri, and-2,4-di-, and 2-O-methyl-D-galactose, 3,4,6-tri-, 3,4-di-, and 4-O-methyl-D-mannose, and 2,3-di-O-methyl-D-glucose. Degradation of periodate-oxidised carboxy-reduced leiocarpan A affords 2-O-α-D-mannopyranosyl-D-erythritol and a degraded polysaccharide from which fragments of lower molecular weight are obtained on further degradation. The structure of leiocarpan A is discussed in the light of these and previous experiments.

Zweidimensionale Dünnschichtchromatographie von Zuckern

Complex sugar mixtures can be separated and identified by twodimensional thin-layer chromatography using borate-impregnated silica gel G/kieselguhr G as carrier material. The separation of the solvent mixtureiso-butanol/glacial acetic acid/water (5∶4∶1) during chromatography in the first dimension and the subsequent intermediate drying cause a polyzonal (graduated in zones) activation of the sorption layer. In this way, the critical sugar mixtures in one-dimensional thin-layer chromatography can be separated in the second dimension using the solvent system propanol/water (8.5∶1.5) orn-propanol/dimethyl sulphoxide/water (8.6∶0.5∶0.9).

The degradation of lactose by interaction with casein

Lactose and casein react to give a complex mixture of sugars and acids from which lactulose, D-galactose, D-tagatose, 5-hydroxymethylfurfural, lactic acid, glycollic acid, phosphoric acid, and the lactones of 2-deoxy-D-glycero-tetronic and 3-deoxy-D-erythro-pentonic acids have been isolated and identified.

THE CONSTITUTION OF A SYNTHETIC XYLAN: III. METHYLATION STUDIES

Hydrolysis of the fully methylated xylan gave a complex mixture of sugars indicating the highly branched nature of the polysaccharide. At least 27% of the internal xylose units were furanose and 38% of the terminal units were also furanose.