The physical aging characteristics of maltose glasses aged at two temperatures below the glass transition temperature, Tg, (Tg-10C and Tg-20C) from 5 to 10 000 min were measured by standard differential scanning calorimetry (SDSC) and modulated differential
scanning calorimetry (MDSC). The experimentally measured instrumental Tg, the calculated Tg, and the excess enthalpy values were obtained for aged glasses using both DSC methods. The development of excess enthalpy
as a function of aging time, as measured by both SDSC and MDSC, was fit using the Cowie and Ferguson and Tool-Narayanswamy-Moynihan
models. The change in the Tg values and the development of the excess enthalpy resulting from physical aging measured by the two DSC methods are discussed.
Authors:Ali Mohammad, Asma Siddiq, Abdul Moheman, and Gaber El-Desoky
A mobile phase system comprising of ethyl acetate and propionic acid in 1:1 (v/v) ratio was identified as the most suitable green mobile phase for selective separation of maltose from fructose, dextrose, galactose, or mannose on precoated silica gel 60 HPTLC plates. The effect of presence of inorganic cations as impurities in the sample was examined for the separation of sugars. The chromatographic parameters like ΔRF, separation factor (α), and resolution (Rs) of separated components of the mixture of maltose-fructose, maltose-dextrose, maltose-galactose, and maltose-mannose were calculated. The limits of detection for fructose, dextrose, and mannose were 7.5 ± 0.41 μg spot−1 and for maltose and galactose were 1.5 ± 0.09 μg spot-1. The proposed method is rapid, sensitive, and free from the use of toxic organic solvents and is therefore environmentally safe. Maltose has been selectively identified in the presence of fructose, dextrose, galactose, and mannose using scanning densitometry.
Authors:Nevena Popovic, Bernard Fried, and Joseph Sherma
Biomphalaria glabrata snails were infected with Schistosoma mansoni and maintained at different dilutions of artificial ocean water for up to 4 weeks. Glucose and maltose concentration of the digestive gland-gonad complex were analyzed by high-performance thin-layer chromatography at different stages of the infection. B. glabrata snails were divided into three experimental groups: Group A, snails with early prepatent infection (10 days post-infection); Group B, snails with late prepatent infection (22 days post-infection); and Group C, snails with patent infection (45 days post-infection). Infected snails in A were maintained at different salinities for 2 weeks and then necropsied, and their two main simple sugars, i.e., glucose and maltose, were analyzed. Groups B and C contained two subgroups: the first subgoups were analyzed after 2 weeks, and the second after 4 weeks. Controls for these experiments were maintained identically in either deionized water or artificial spring water. Maltose and glucose were extracted from the digestive gland-gonad complex in ethanol-water (70:30). 1-Butanol-glacial acetic acid-diethyl ether-deionized water (27:18:5:3) mobile phase was used to separate sugars on EMD Millipore silica gel preadsorbent plates. Sugars were detected using α-naphthol-sulfuric acid reagent and quantified with a CAMAG TLC Scanner 3 at 515 nm. The obtained data were compared using analysis of variance (ANOVA) single factor statistical analysis. Statistical differences were not found in any sugars in Group A snails. For glucose, a significant difference was found after 4 weeks in both B and C snails. For maltose, a significant difference was found after 4 weeks in B snails and after 2 weeks in C snails. Different salinity levels affect the maltose and glucose concentrations of adult B. glabrata snails infected with S. mansoni.
This study is a first attempt to present a report about a high-performance thin-layer chromatography (HPTLC)–densitometric method that has been developed and validated for the quantification of sugars, i.e., glucose, fructose, sucrose, maltose, and raffinose from the methanol extracts of roots of 7 Asparagus species ‒ A. adscendens, A. racemosus, A. retrofractus, A. officinalis, A. densiflorus, A. falcatus, and A. sprengeri. The separation and quantification of sugars were achieved using the mobile phase propanol‒ethyl acetate‒ water (6:3:1, v/v). Derivatization of the bands was done by using diphenylamine, aniline, and ortho-phosphoric acid reagents, and densitometric scanning was done at 600 nm in absorbance–reflectance mode. This method gave the best resolution of bands at RF = 0.55, 0.50, 0.31, 0.11, and 0.46, corresponding to fructose, glucose, maltose, raffinose, and sucrose, respectively. The calibration curves were linear in the range of 100–500 ng per spot. The limit of detection (LOD) and the limit of quantification (LOQ) ranged between 12.77–75.48 ng and 38.69–228.73 ng, respectively. The intraand inter-day precisions were found between 0.33–1.46 in terms of relative standard deviation (RSD). The average recoveries ranged between 97.84 –99.91%. The validated method was successfully used to detect and quantify sugars in the methanol root extracts of the 7 Asparagus species.
Authors:B. Wierczinski, G. Müllen, and S. Rosenhauer
Cryosublimation is one technique, which allows the accumulation of tritium from aqueous solutions using certain chemical compounds.
After studying several inorganic compounds such as zeolites and metal salts,1 as well as some humic substances,2 we have now investigated several mono-and polysaccharides, such as glucose, maltose, galactose, starch, agar, and gelatine.
Except for starch all of the above mentioned compounds showed a clear enrichment of tritium. The highest value was reached
for Agartine, which gave an enrichment factor of 6.2. Since mono-and polysaccharides form weak hydrogen bonds, these results
prove again our theory that tritium is preferably accumulated in exchangeable hydrogen bonds.
Authors:Paola Pani, Marco Signorelli, Alberto Schiraldi, and Danila Torreggiani
Classical thermogravimetry and its modification with Knudsen cells were employed to quantitatively investigate the osmo-dehydration
of apple pulp samples. The data allowed realization of the complex mechanism of the process, which is not a mere solvent depletion,
since it also implies sugar exchanges between the apple tissue and the hypertonic syrup used to dehydrate the fruit. The comparison
between different hypertonic syrups, all at the same water activity, showed that maltose is more effective than either sucrose
or a mixture of sugars that mimics the saccharide content of the apple. The conclusions are supported by a thermodynamic analysis
of the aqueous solutions of these sugars at a concentration level as large as that of the hypertonic syrups used for the osmo-dehydration
Authors:D. Champion, C. Loupiac, D. Russo, D. Simatos, and J. M. Zanotti
structural and functional alterations of these systems. The ability of sugars to preserve biomolecules during freezing has been recognized for years. The disaccharides most often described in literature for this aim are sucrose, maltose, and trehalose. This
Authors:David Tjandra Nugraha and Fransiscus Sabatino Bata
elongation of hypocotyl as it pushes cotyledon to the surface ( Bewley and Black, 1983 ). During the germination process, the starch content is converted into smaller parts of glucose and maltose. Glucose and fructose content increases by tenfold and sucrose