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Journal of Thermal Analysis and Calorimetry
Authors: Libby Yoerg, M. Ellen Matthews, Lakshmi Kaza, Naullage Indika Perera, David W. Ball, John Moran, and Alan T. Riga

Introduction Monosaccharides are the most basic units of biologically important carbohydrates. They are usually the simplest structures of sugar and are typically colorless, water-soluble, and crystalline solids. Some

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In this paper we present results from recent studies focusing on elucidation of the mechanism of visualization of simple sugars (e.g. d -(+)-glucose, d -(+)-galactose, and d -(−)-fructose) developed on glass TLC plates precoated with 3-aminopropyl chemically bonded stationary phase and then heated at elevated temperatures, a method originally developed, then recommended commercially, by Merck.Detection of the sugars under UV illumination is possible because of their substantial fluorescence; this suggests that during heating the analytes probably undergo a process which results in their structural transformation. We postulated a possible analogy with the Maillard reaction, omnipresent in innumerable living organisms.To verify our assumption we performed analysis with high-performance thin-layer chromatography (HPTLC), high-performance liquid chromatography (HPLC), and IR, UV, and fluorescence spectroscopy. All the results obtained seem to confirm the analogy between the Maillard reaction and the reaction of simple carbohydrates after development on the amino stationary phase.

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Acta Alimentaria
Authors: M. Korošec, J. Bertoncelj, A. Pereyra Gonzales, U. Kropf, U. Golob, and T. Golob

Honey consists of simple carbohydrates. Glucose and fructose represent the majority of honey’s carbohydrate profile, while a spectrum of oligosaccharides is in minority, but typical for the honey type regarding its main source nectar or honeydew, respectively. The content of different carbohydrates was determined in 63 samples of four types of Slovenian honey (acacia, spruce, multifloral and forest honey). The honey samples were of different botanical and geographical origin, and were analysed six to ten months after harvest. The type of honey was determined by sensory analysis and electrical conductometry. In order to determine the content of monosaccharides and oligosaccharides high-pressure anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was used. The applied chromatographic method with pulsed amperometric detection enables reliable and selective detection of carbohydrates, especially oligosaccharides, in honey. Statistical comparison of the results showed that there were statistically significant differences among some parameters, while for others such differences did not exist. The results of our research and available data of other authors propose that the carbohydrate profile (the presence of individual carbohydrates in honey) and the content of carbohydrates in honey may have a potentially valuable role in the assessment of botanical origin of honey and as an indicator of putative adulteration of honey with sugar mixes or syrups, respectively. Nevertheless, analysis on numerous samples and different honey types are needed.

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. They are non-toxic, water-soluble, inexpensive and renewable substances. Moreover, derivatives of monosaccharides can be used as organic monomers in gelcasting process, they can be easily removed from samples during binder decomposition process and they

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Journal of Thermal Analysis and Calorimetry
Authors: C. Shimasaki, T. Kanaki, S. Takeuchi, K. Hasegawa, D. Horita, E. Tsukurimichi, and T. Yoshimura

Abstract  

The pyrolysis of trimethylsilyl derivatives of saccharides (1) was investigated by DTA-TG, MS, GC/MS and TG-GC/MS. The DTA-TG/DTG curves showed that the pyrolysis of 1 occurred in one stage. The exothermic peaks were due to sublimation or thermal decomposition by vaporization. The cleavage mechanism by electron impact of 1 was classified into four categories: 1) stepwise elimination of the side-chain, 2) cleavage of the side-chain, 3) cleavage of the pyranose ring, and 4) cleavage of the pyranose ring and side-chain at the same time. The mass-spectrum for 1 revealed the main common four fragment ions, such asm/z 73, 191, 204 and 217, with cleavage of the pyranose ring. These fragment ions were detected with a similar retention time in the gas cromatogram by GC/MS or TG-GC/MS. The retention time for 1 increased in the sequence aldopentose<ketohexose<aldohexose. This result indicates that the trimethylsilyl derivatives are thermally stable. Subsequently, the pyrolysis regime for 1 obeyed apparent 1/2-order kinetics and their apparent activation energy was estimated as 75–100 kJ/mole.

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from litchi seeds were isolated and purified. Monosaccharide compositions and in vitro hypoglycaemic effects of 3 polysaccharides were analysed. This study provides experimental evidences for the exploitation and utilisation of litchi seeds as a new

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. Rev., 2005, 10 (4), 294–306. 16 Cura, A. J., Carruthers, A.: The role of monosaccharide transport proteins in carbohydrate assimilation, distribution, metabolism and

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A simple, rapid, and effective high-performance thin-layer chromatographic (HPTLC) method has been established for differentiating among the polysaccharides present in six traditional Chinese medicines (TCM), Cordyceps sinensis, Ganoderma lucidum, Astragalus memberanaceus, Panax ginseng, Panax quinquefolii , and Panax notogiseng . Acid hydrolyzates of the polysaccharides were analyzed by HPTLC with two detection reagents, aniline-diphenylamine-phosphoric acid and ninhydrin, and scanning densitometry. The compounds were separated on silica gel plates with chloroform- n -butanol-methanol-acetic acid-water 4.5:12.5:5:1.5:1.5 ( v/v ) as mobile phase. Seven monosaccharides and two glucuronic acids were used as reference compounds. The results showed that hydrolysis of polysaccharides can release specific molecules present in the herbal species in addition to the monosaccharides present. This is useful for distinguishing the origins of the polysaccharides in Chinese medicines.

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A simple thin-layer chromatographic method suitable for monitoring microbiological fermentation processes is reported. In addition to compounds related to the target compound the method enables acquisition of data on the formation and degradation of a series of carbohydrates from starch to monosaccharides. The target compounds and the carbohydrates can both be analyzed by use of a single method using one layer only. Both sets of data are useful for optimization of different biosyntheses or bioconversions. The method involves one, effective, thin-layer chromatographic separation, subsequent charring with sulfuric acid solution as detection reagent, heating, and evaluation by scanning the colored spots.

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Abstract

Detailed thermal analysis studies have shown that a ‘molten starch’ phase is obtained during controlled heating of starch. Before the ‘molten’ stage, depolymerisation of starch produces lower molecular weight compounds like dextrins, oligo, di- and monosaccharides, as well as other types of compounds. These compounds should have ideal properties for plasticizing starches because of the similarities of the molecules, helping lower phase changes in collaboration with molecular weight decrease. Interestingly, it was found previously that these materials only act as adhesives in a narrow temperature range around 523 K (250 °C) (Shuttleworth et al. J Mater Chem 19(45):8589–8593, ). Materials were investigated using thermal and mechanical analyses of single lap joints.

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