The distinctive flavor of coffee is certainly the principal reason for high acceptability of the beverage prepared from roasted coffee. Even before the introduction of gas chromatography coupled with mass spectrometry Reichstein and Staudinger made an outstanding contribution by characterizing more than 70 flavor compounds (among them several key odorants) in roasted coffee. Since 1960 the list of constituents increased to 300 in green coffee, and to 850 in roasted coffee, respectively. Many natural flavor compounds were first identified in roasted coffee and were later characterized as key compounds in certain processed foods. Due to the high selectivity of the olfactory system, bioactive compounds must be evaluated by determination of odor activity values or by gas chromatography olfactory methods.
Comparable to other foods the number of key odorants of roasted coffee is drastically reduced by these methods. Sensory properties of individual compounds may be changed by interaction, generating new aroma qualities or might lead to supression of odorants. Green coffee beans contain compounds with extremely low sensory thresholds obviously formed by microorganisms during fermentation and processing. To some extent these contaminants are transferred to roasted coffee influencing flavor and quality. During roasting more than 500 compounds are formed by Strecker and Mailard reactions as predominant reactions. Specifi precursors, pathways and a better insight into the fundamental chemistry leading to key flavour compounds may be elucidated by new analytical techniques in the future.
It was a great pleasure for me to read this comprehensive review on Coffee Flavor Chemistry. In my opinion it is an excellent data base for coffee flavor chemistry.
Prof. Dr. Roland Tressl
Technischen Universitat, Berlin
Table of Contents
- Green Coffee
- From the raw bean to the roasted coffee
- A historical survey of coffee aroma research
- The individual constituents : structure, nomenclature, origin, chemical and organoleptic properties
Coffee Flavor Chemistry