Organic geochemistry of Amynteo lignite deposit, northern Greece: a Multi-analytical approach
Iordanidis, A. ; Schwarzbauer, J. ; Georgakopoulos, A. ; Lagen, B. van - \ 2012
Geochemistry international 50 (2012)2. - ISSN 0016-7029 - p. 159 - 178.
maritza-east lignite - c-13 cp/mas nmr - rich mine soils - bituminous coal - brown-coal - ftir spectroscopy - humic substances - new-zealand - crude oils - py-gc/ms
Several lignite samples were collected from boreholes of the Amynteo opencast lignite mine, northern Greece. Organic geochemical characteristics were investigated with the help of various analytical techniques, comprising Gas Chromatography (GC) and Gas-chromatography-Mass Spectrometry (GC-MS), Fourier Transform Infrared Spectroscopy (FTIR), solid-state Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) spectroscopy, petrographical measurements as well as determination of bulk parameters. In the low rank (Rr = 0.21%) Amynteo lignites, huminite is the most abundant maceral group, inertinite has relatively low percentages and liptinite concentrations are rather high. Carbon Preference Index (CPI) reveals the predominance of odd-numbered, long-chained aliphatic hydro-carbons, which is related to a higher terrestrial plant input. The Pr/Ph ratio suggests that reducing conditions were persistent during peatification. Gymnosperm biomarkers such as isoprimarane, abietane, phyllocladane and sandaracopimarane, as well as angiosperm indicators (lupane) and hopanoid compounds with bacterial origin were identified. Analyses of the aromatic fractions revealed the presence of naphthalene, alkyl benzenes and phenols, pyrene, cadalene, cadinane, fluoranthene and dibenzofurane. Based on the FTIR analysis, aliphatic and oxygen containing structures were prevailed over the aromatic moieties. The intensity of the mineral bands was preferentially increased in the FTIR spectra of insoluble material. According to NMR analysis, the aliphatic carbons (0-50 ppm) have higher proportions comparing to aromatic carbons (100-160 ppm). The aromaticity fraction is low (fa = 0.32), as expected for these low rank coals. The presence of free organic radicals and Fe3+ and Mn2+ paramagnetic ions was revealed by EPR. In summary, the combined application of complementary analytical techniques allowed a deep inside into the geochemical characteristics of Amynteo lignites.
Crystallinity changes in wheat starch during the bread-making process: starch crystallinity in the bread crust
Primo-Martin, C. ; Nieuwenhuijzen, N.H. van; Hamer, R.J. ; Vliet, T. van - \ 2007
Journal of Cereal Science 45 (2007)2. - ISSN 0733-5210 - p. 219 - 226.
heat-moisture treatment - mas nmr-spectroscopy - c-13 cp/mas nmr - phase-transitions - water-system - amylose - gelatinization - amylopectin - polymorphs - potato
The crystallinity of starch in crispy bread crust was quantified using several different techniques. Confocal scanning laser microscopy (CSLM) demonstrated the presence of granular starch in the crust and remnants of granules when moving towards the crumb. Differential scanning calorimetry (DSC) showed an endothermic transition at 70 degrees C associated with the melting of crystalline amylopectin. The relative starch crystallinity, as determined by X-ray and DSC, from different types of breads was found to lie between 36% and 41 % (X-ray) and between 32% and 43 % (DSC) for fresh bread crust. Storage of breads in a closed box (22 degrees C) for up to 20 days showed an increase in crust crystallinity due to amylopectin retrogradation both by X-ray and DSC. However, DSC thermograms of 1-day old bread crust showed no amylopectin retrogradation and after 2 days storage, antylopectin retrogradation in the crust was hardly detectable. C-13 CP MAS NMR was used to characterize the physical state of starch in flour and bread crumb and crust. The intensity of the peaks showed a dependence on the degree of starch gelatinization. Comparison of the results for two different types of bread showed that the baking process influenced the extent of starch crystallinity in the bread crust. Antylopectin retrogradation, which is the main process responsible for the staling of bread crumb, cannot be responsible for crispness deterioration of the crust as amylopectin retrogradation upon storage of breads could only be measured in the crust after 2 days storage. Under the same conditions loss of bread crust crispness proceeds over shorter times.