Determination of aroma and bitter characteristic of Iranian hop (Humulus lupulus L.) variety by essential oil analysis

Hop (Humulus lupulus L) is cultivated worldwide for two purposes of aroma and bitter taste. The main objective of this study was to determine the predominant characteristic of hop cultivated in Iran using GC-MS analysis of essential oils obtained from fresh and heat dried hop strobiles. Essential oils (EO) of female flowers of hop (Humulus lupulus L.) cultivated in Gorgan, Iran were obtained by hydro-distillation and the main components were identified and assessed by GC-MS analysis using computer database search or comparison with standard peaks from literature. Percentage of the main constituents of EO obtained from fresh and dried flowers were ?-caryophyllene (13.08, 2.67), ?-myrcene (12.82, 0.03), alloaromadendrene (3.59, 1.53), ?-farnesene (1.94, 0.74), ?-limonene (1.77, 0.04), linalool (1.12, 0.03), ?-pinene (0.78, 0.01), ?-humulen (0.38, 0.18) and ?-pinene (0.11, 0.01), respectively. Based on other investigations, the high ratio of ?-caryophyllene and alloaromadendrene in Essential oil can be used as an index for determining bitter characteristic in hop. Data obtained from GC-MS analysis also revealed high ratio of these two components in EO obtained from fresh hop of Iran, therefore the hop of Iran could be classified as a variety with predominant bitter characteristic.