@article{KinuthiaFrohmeBroedeletal.2017, author = {Kinuthia, Chuaga and Frohme, Marcus and Br{\"o}del, Oliver and Mugendi, Beatrice}, title = {LCMS Analysis of Biochemical Composition in Different Kenyan Coffee Classifications}, series = {Food Science and Quality Management}, volume = {69}, journal = {Food Science and Quality Management}, issn = {2225-0557}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10185}, pages = {44 -- 52}, year = {2017}, abstract = {Kenyan coffee is classified by defects after grading by the 'Devonshire method.' The method involves classification of the coffee beans into different classes based on the raw and roasted coffees and cup quality, with class one being the best and ten the poorest. In this study, the relationship between classification of the coffee and the content of sucrose, trigonelline, caffeine and chlorogenic acids was determined by simultaneous LC-MS analysis. By using the sensory variables the class 3 coffee portrayed the best quality, followed by class 4 and 5 which were placed further distinctively from the other classes (6, 7, 8 and 9). The class 3 coffee had a high percent of non-defective beans with 94.31\% and class 9 had a high defect count at 79.53\% hence the defective beans increased with decrease in coffee class. The caffeine concentration in green coffee for class 3 coffee was significantly different from the rest of the coffees at 1.23 ± 0.00g/100g. A higher content of trigonelline levels was observed as the quality of the green coffee decreased in classes 6, 7 and 8. The highest level of sucrose in green coffee beans was observed in class 3 coffee and the lowest in the class 9. Lower content of chlorogenic acids were observed among the high quality coffees i.e. class 3, 4 and 5 with class 3 having the lowest while a higher content was observed among the lower quality coffees i.e. classes 6, 7 and 9 with class 6 having a higher content was it significantly different in class 6 compared to 7 and 9?. Quantities of different chemical components among the classes are clear indicators that the classification method used on the Kenyan coffees brings out the differences in coffee quality based on the analysis of the green and the roasted coffees.}, language = {en} } @article{KipkorirMuhohoMuliroetal.2015, author = {Kipkorir, R. and Muhoho, S. and Muliro, P. and Mugendi, Beatrice and Frohme, Marcus and Br{\"o}del, Oliver}, title = {Effects of Coffee Processing Technologies on Aroma Profiles and Sensory Quality of Ruiru 11 and SL 28 Kenyan Coffee Varieties}, series = {Asian Journal of Agriculture and Food Sciences}, volume = {3}, journal = {Asian Journal of Agriculture and Food Sciences}, number = {2}, issn = {2321-1571}, doi = {10.15771/2321-1571_2015_1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6482}, pages = {178 -- 188}, year = {2015}, abstract = {The study aimed at comparing the effects of three coffee processing methods on aroma profiles and sensory quality of Ruiru 11 and SL 28 coffee varieties. The processing methods varied on stages of processing and method of mucilage removal. The green coffee beans obtained from the three processing methods were graded and roasted, ground and analyzed for the aroma profiles and sensory quality. Headspace Solid phase Microextraction fibre (SPME) technique were used for the extraction of aroma compounds from coffee samples and characterization of the compounds with use of gas chromatography mass spectrometry (GC-MS). Sensory quality were analyzed by an expert panelist. Various volatile aroma compounds were identified in roasted coffee and classified into their chemical classes involving furans, ketones, pyrazines ketones pyridines, pyrroles and acids. The intensity of aroma compounds were compared in terms of their peak areas and variations were noted between the processing methods with the ecopulper showing higher levels of pyrazines such as 2-methylpyrazine, 2-ethyl-6-methylpyrazine, and wet pulper showing higher levels of furans such as furfuryl formate and furfuryl alcohol, acetate. The hand pulper was high in the level of acids and esters such as acetic acid and propanoic acid, ethyl ester. Similar aroma compounds were identified in headspace of Ruiru 11 and SL 28 and there were variations in the intensities of aroma groups such as pyrroles and pyridines. It was concluded that the eco-pulper and hand pulper methods gives better aroma quality than the wet pulper while SL 28 variety gives higher sensory quality than Ruiru 11.}, language = {en} } @misc{GeringKoberBroedeletal.2017, author = {Gering, Vanessa and Kober, Liane and Br{\"o}del, Oliver and Koskei, Richard and Mugendi, Beatrice and Frohme, Marcus}, title = {LC-MS/MS als Methode zur Detektion und Quantifizierung der Inhaltsstoffe in Kaffee}, series = {Wissenschaftliche Beitr{\"a}ge 2017}, volume = {21}, journal = {Wissenschaftliche Beitr{\"a}ge 2017}, issn = {0949-8214}, doi = {10.15771/0949-8214_2017_1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9362}, pages = {7 -- 12}, year = {2017}, abstract = {Kaffee ist das wohl popul{\"a}rste Heißgetr{\"a}nk weltweit. Zwei botanische Arten sind f{\"u}r den Weltmarkt von Bedeutung und unterscheiden sich bez{\"u}glich ihres Anbaugebietes und der Inhaltsstoffe. Kaffee enth{\"a}lt {\"u}ber 850 bisher identifizierte Aromastoffe, welche den Geschmack bilden. Außerdem haben die Prozessierung der geernteten Kirsche bis zur Bohne, das R{\"o}stprofil und das Aufbr{\"u}hen einen großen Einfluss darauf. In dieser Arbeit wurde die Auswirkung der Prozessierungsmethode auf ausgew{\"a}hlte Inhaltsstoffe mit Hilfe der Fl{\"u}sssig-Chromatographie-Tandem-Massenspektroskopie (LC-MS/MS) untersucht. Daf{\"u}r wurden drei Prozessierungsmethoden, die unterschiedlich viel Wasser f{\"u}r das Abl{\"o}sen des Fruchtfleisches von den Kaffeekirschen ben{\"o}tigen, und zwei Kultursorten miteinander verglichen. Die Ergebnisse zeigten einen geringf{\"u}gig h{\"o}heren Gehalt der zwei wichtigsten Inhaltsstoffe Koffein und Chlorogens{\"a}ure in den Bohnen, bei deren Prozessierung im Eco-Pulper-Verfahren weniger Wasser eingesetzt wurde. Bis auf einen verringerten Gehalt an Saccharose wurde f{\"u}r weitere wichtige Inhaltsstoffe (Acrylamid, Niacin, Zitronens{\"a}ure und Vanillin) kein signifikanter Unterschied bei h{\"o}herem Wassereinsatz gefunden. Insofern man die untersuchten Inhaltsstoffe als Qualit{\"a}tsmarker betrachtet, ist im Vergleich zu den anderen Prozessierungsmethoden das Eco-Pulper-Verfahren die beste Wahl, insbesondere da es als wassersparende Methode einen entscheidenden Beitrag zur Nachhaltigkeit des Kaffeeanbaus leistet.}, language = {de} }