Monitoring of volatile substances in the coffee

Bc. Sabina Kožichová

Master's thesis

Abstract:

Coffee is one of the major socioeconomic crops with a direct impact on the development of producing countries. Aroma, resulting from a complex mixture of volatile substances, is the most important quality and price determinant. The chemical changes occurring in the volatile profiles of roasted Coffea arabica beans during storage under two different conditions (room temperature, refrigerator) for the period of 15 weeks have been characterized by means of HS-SPME in combination with GC-MS. A total of 65 volatile compounds, including 7 potent odourants, were identified and quantified in samples of four diverse geographical origins. No off-flavour compounds were generated during the research in any of the samples. The only new substances emerged were dodecane and p-cymene. The complete loss of 3-ethyl-1,2-cyclopentanedione was detected in samples stored in the refrigerator. The total loss of another substance did not occur, but the overall considerable volumetric decrease of volatile substances in roasted coffee beans over time has been confirmed. Significant drops in volume have occurred, beside others, in the case of 2-methylbutanal, 3-methylbutanal, and 2,3-pentanedione, which are ranked among the important odourants. Only minimum of substances remained completely inert to the different storage temperatures throughout the research. In general, study demonstrated decreasing rate of loss of the volatile substance when storing the samples in the refrigerator. Minor fluctuations in reactions to storage conditions were also noted in accordance to coffee's origin. Disturbance of the balance of potent volatile compounds was assessed as the main cause leading to coffee quality degradation.

Keywords

Coffea arabica, volatile compounds, SPME, GC-MS, storage, temperature, aroma

Jazyk práce: English

Datum vytvoření / odevzdání či podání práce: 25. 4. 2018

Obhajoba závěrečné práce

• Vedúci: Ing. Klára Urbanová, Ph.D.

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Master programme / odbor:
Tropical Agriculture / Sustainable Rural Development in the Tropics and Subtropics