Obsah kofeinu v kávovém nálevu připraveném za různých podmínek.

This thesis focuses on monitoring the contents of caffeine in selected kinds of roasted ground coffee and soluble coffee. The respective samples were used to prepare coffee extracts to which various ingredients were added. The contents of caffeine were determined using high-performance liquid chromatography. The theoretical part of this thesis contains a brief description of history of coffee, coffee plant species, composition and processing methods of coffee beans and methods for preparing coffee beverage. Furthermore, the work describes the effects and metabolism of caffeine, its occurrence and use. The practical part deals with methodology for determining the contents of caffeine in coffee extracts using HPLC chromatographic methods. The caffeine content in coffee extracts of roasted ground coffee ranged from 246,4 mg/l - 529,5 mg/l. The ground decaffeinated coffee, caffeine content ranged from 11,0 mg/l - 17,9 mg/l. The caffeine content in coffee extracts soluble coffee ranged from 564,1 mg/l - 1596,2 mg/l.