Chemometric analysis of hop essential oils

Abstract

Humulus lupulus (H. lupulus) L., more commonly known as hops, is a member of the Cannabaceae family native in Europe including Lithuania, Asia and North America. An important class of hop compounds is the essential oils, which gives specific hop aroma. As each hop variety has atypical essential oil pattern, the analyses of hops essential oils can be used to identify hop varieties [1]. Specimens from the collection of hop varieties and wild forms cultivated at Kaunas Botanical Garden of Vytautas Magnus University, where all plants grow in equal climatic and soil conditions, were subjected to gas chromatographic - mass spectrometric analysis. Hop essential oil is dominated by major compounds like humulene, myrcene, caryophyllene, whereas other constituents are found in less abundance. Several statistical data analysis approaches were used to evaluate essential oil pattern in different species. Hierarchical clustering, principal component analysis and K-means clustering analysis were performed. Differently treated input data was used to establish the most stable and representative method.