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Title: Characterization of Sulfur Compounds in Coffee Beans by Sulfur K-XANES Spectroscopy

Abstract

In this 'feasibility study' the influence of roasting on the sulfur speciation in Mexican coffee beans was investigated by sulfur K-XANES Spectroscopy. Spectra of green and slightly roasted beans could be fitted to a linear combination of 'standard' reference spectra for biological samples, whereas longer roasting obviously involves formation of additional sulfur compounds in considerable amounts.

Authors:
;  [1];  [2];  [1];  [2];  [3]
  1. Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Hwy., Baton Rouge, LA 70806 (United States)
  2. (Germany)
  3. Institute of Physics, University of Bonn, Nussallee 12, 53115 Bonn (Germany)
Publication Date:
OSTI Identifier:
21054754
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644676; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; BIOTECHNOLOGY; CHEMICAL STATE; COFFEE BEANS; FEASIBILITY STUDIES; FOOD PROCESSING; ROASTING; SULFUR; SULFUR COMPOUNDS; X-RAY SPECTRA; X-RAY SPECTROSCOPY

Citation Formats

Lichtenberg, H., Hormes, J., Institute of Physics, University of Bonn, Nussallee 12, 53115 Bonn, Prange, A., Niederrhein University of Applied Sciences, Rheydter Strasse 277, 41065 Moenchengladbach, and Modrow, H.. Characterization of Sulfur Compounds in Coffee Beans by Sulfur K-XANES Spectroscopy. United States: N. p., 2007. Web. doi:10.1063/1.2644676.
Lichtenberg, H., Hormes, J., Institute of Physics, University of Bonn, Nussallee 12, 53115 Bonn, Prange, A., Niederrhein University of Applied Sciences, Rheydter Strasse 277, 41065 Moenchengladbach, & Modrow, H.. Characterization of Sulfur Compounds in Coffee Beans by Sulfur K-XANES Spectroscopy. United States. doi:10.1063/1.2644676.
Lichtenberg, H., Hormes, J., Institute of Physics, University of Bonn, Nussallee 12, 53115 Bonn, Prange, A., Niederrhein University of Applied Sciences, Rheydter Strasse 277, 41065 Moenchengladbach, and Modrow, H.. Fri . "Characterization of Sulfur Compounds in Coffee Beans by Sulfur K-XANES Spectroscopy". United States. doi:10.1063/1.2644676.
@article{osti_21054754,
title = {Characterization of Sulfur Compounds in Coffee Beans by Sulfur K-XANES Spectroscopy},
author = {Lichtenberg, H. and Hormes, J. and Institute of Physics, University of Bonn, Nussallee 12, 53115 Bonn and Prange, A. and Niederrhein University of Applied Sciences, Rheydter Strasse 277, 41065 Moenchengladbach and Modrow, H.},
abstractNote = {In this 'feasibility study' the influence of roasting on the sulfur speciation in Mexican coffee beans was investigated by sulfur K-XANES Spectroscopy. Spectra of green and slightly roasted beans could be fitted to a linear combination of 'standard' reference spectra for biological samples, whereas longer roasting obviously involves formation of additional sulfur compounds in considerable amounts.},
doi = {10.1063/1.2644676},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • Chemical and isotope analyses on groundwater sulfate, atmospheric deposition sulfate and fulvic acids (FAs) associated sulfur were used to determine the S cycling in a karstic catchment area of the Franconian Alb, Southern Germany. Sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy provided information on the oxidation state and the mechanism of the incorporation of sulfur in FAs. During base flow {delta}{sup 34}S values of groundwater sulfate were slightly depleted to those of recent atmospheric sulfate deposition with mean amount-weighted {delta}{sup 34}S values of around + 3{per_thousand}. The {delta}{sup 18}O values of groundwater sulfate shifted to lower values comparedmore » to those of atmospheric deposition and indicated steadiness from base flow to peak flow. The reduced sulfur species (S{sub -1}/thiol; S{sub 0}/thiophene, disulfide, S{sub +2}2/sulfoxide) of soil FAs averaged around 49% of the total sulfur and {delta}{sup 34}S value in FAs was found to be 0.5{per_thousand}. The formation of polysulfides and thiols in FAs in concert with a decreasing isotope value of {delta}{sup 34}S in FAs with respect to those of atmospheric deposition sulfate suggests oxidation of H{sub 2}S, enriched in the {sup 32}S isotope, with organic material. The depletion of {delta}{sup 18}O-SO{sub 4}{sup 2-} by several per mil in groundwater sulfate with respect to those of atmospheric deposition is, therefore, consistent with the hypothesis that SO{sub 4}{sup 2-} has been cycled through the organic S pool as well as that groundwater sulfate is formed by oxidation of H{sub 2}S with organic matter in the mineral soil of the catchment area.« less
  • No abstract prepared.
  • Sulphur K-edge X-ray absorption near edge structure (XANES) spectroscopy was used to quantify S species in humic substance extracts from ten soils from the UK, China and New Zealand, which differ in land use and agricultural management. XANES spectroscopy showed the presence of most reduced (sulphides, disulphides, thiols and thiophenes), intermediate (sulphoxides and sulphonates) and highly oxidised S (ester sulphates) forms, with the three groups representing 14-32%, 33-50% and 22-53% of the organic S in the humic substance extracts, respectively. Land use had a profound influence on the relative proportions of S species. Well-drained arable soils generally had a highermore » proportion of organic S present in the most oxidised form than the grassland soils collected nearby, whereas paddy soils showed a more reduced profile due to episodic flooding. In the Broadbalk Classical Experiment at Rothamsted, reversion of an arable system to grassland or woodland in the 1880s resulted in an increase of the most reduced and intermediate S species at the expense of the most oxidised S species. Long-term applications of farmyard manure to an arable plot also shifted S species from the most oxidised to the intermediate and the most reduced species. Sulphur immobilisation and gross mineralisation were determined in seven soils using the {sup 35}S isotope dilution method. Gross mineralisation during a 53-day incubation correlated more closely with the amounts of the most reduced and intermediate S species than with the most oxidised S species, suggesting that the former (C-bonded S) were the main source of organic S for mineralisation in the short-term.« less