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MO: Fachverband Molekülphysik

MO 23: Experimentelle Techniken

MO 23.3: Poster

Thursday, March 13, 2008, 16:30–19:00, Poster C1

Raman Spectroscopy for the Characterization of Coffee — •Rasha Hassanein, Patrice Donfack, Malte Sackmann, and Arnulf Materny — Jacobs University Bremen, Germany

Coffee is one of the most popular beverages around the world. The varieties of coffee are directly influenced by environmental conditions and by the various methods of processing especially roasting, which consequently affect the quality of coffee. The discrimination between coffee species and blends for the purpose of monitoring quality and detecting fraud is difficult, since the chemical composition of coffee varieties is complex and many parameters are influencing the quality. Therefore, it is necessary to find parameters suitable for the differentiation of coffee. Recently, we have proposed Raman spectroscopy as a possible way to characterize coffee varieties of different geographical origins and roasting degrees. This is achieved by analyzing the volatile fraction and key components of coffee. The amounts and composition of flavor precursors in green coffee have a dramatic effect on the quality of the final roasted coffee. For example, trigonelline - which is common in raw coffee beans - plays a significant role not only in forming the aroma and flavor but also since antioxidant chemicals are formed during the roasting process. We have taken Raman spectra and analyzed them in order to identify trigonelline in green coffee from different geographical regions. Additionally, we have taken spectra of vapor extractions from coffees based on freshly grounded beans as well as from instant coffee. Clear differences could be detected, which are discussed with respect to their importance in assessing the quality of coffee.