Analysis of Humulus lupulus L. essential oils and bitter acids

Abstract

The object of this research is Humulus lupulus L. one of the many medicinal plants, which has wide application in beer production industry. This is aromatic, multi-climber common hop (Humulus lupulus L.), which is growing throughout the territory of Lithuania. Traditional medicine knew hops cones in VIII century and used for insomnia, as nerve sedative, improving digestion, stimulating the release of urine, pain and seizures depressing measure of cough, fever, diarrhea, inflammation, and rheumatism. It is known that hop cones have antibacterial, fungicidal properties and estrogenic activity. Hop cones accumulate essential oil (1.0-3.0%) containing β-pinene, β-myrcene, caryophyllene, α-caryophyllene and other volatile compounds. Important biologically active compounds group is bitter accids (5.0-20.0%): alpha-bitter acid (humulone), beta-bitter acid (lupulone), enzymes, flavonoids (rutin, isoquercitrine etc.), anthocyanins (0.3%), leukoantocianidine, ascorbic acid, and vitamin B1. The aimof this study was to determine and compare the 2010, 2011 and 2012 harvests and different varieties of hops (Humulus lupulus L.) essential oils composition and bitter acid compositions using gas chromatography-mass spectrometry and capillary electrophoresis methods. For the analysis raw material of common hop (Humulus lupulus L.) cones was collected at Kaunas Botanical Garden of Vytautas Magnus University hops collection. The raw material of collected cones was dried in a well ventilated room, avoiding direct sunlight. The highest amount of essential oils was determined in hop “Marynka” were identified: α- pinene, β-mircenae; humulene; caryophyllene. This variety of hops was rich with alpha-bitter acid (co-humulone, and ad-humulone) and beta-bitter acid (lupulone).