Introduction
It is commonly known, that hop cones were used in brewery for centuries, because of their aroma and provided bitterness (Zanoli and Zavatti 2008). Each variety of hops has its own typical essential oil pattern which is an important tool for the determination of hop chemotypes, ecotypes or evaluation of hop quality (Katsiotis et al. 1990).
There are many forms of wild hops, which are similar according to their composition, so it is very difficult to distinguish between various ecotypes or phenotypes. In 1926, a collection of hops was created at the Kaunas Botanical Garden of Vytautas Magnus University by K. Grybauskas, where many wild forms and different varieties from Western and Central Europe were collected for scientific investigations and nurturing of new varieties. Hybridization between the climate and plant illness resistant wild forms and highly productive, but less resistant domestic varieties was carried out. Based on that, five new Lithuanian hop varieties were nurtured (Obelevičius 2003). Combination of modern instrumental analysis and chemometric methods provides a possibility to classify various chemotypes of plants, revealing differences of chemical composition of their secondary metabolites. Unique situation, when plants have been cultivated at the same collection (identic edafoclimatic conditions), provides a possibility to focus exclusively on the genetically resulted chemotyping, whereas comparison of several harvests shows the influence of hydrothermal conditions variation on the biosynthesis of secondary metabolites in plants. Over 170–200 compounds can be separated and their quantities estimated using capillary GC analysis of hops essential oils in one run, which is a very suitable tool performing comparative study of different plants by so called chromatographic profiling or fingerprinting (Stankevičius et al. 2007). Evaluation of those results by chemometric methods not only reveals the information analogous to that obtained in genetic analysis, but provides phytochemical composition data, which are indispensible for standardization and quality control of plant raw materials required in food or pharmaceutical industry. High resolution and ability to provide precise and accurate qualitative and quantitative data distinguishes GC-MS analysis as valuable tool for taxonomic studies of plants.
Introduction
It is commonly known, that hop cones were used in brewery for centuries, because of their aroma and provided bitterness (Zanoli and Zavatti 2008). Each variety of hops has its own typical essential oil pattern which is an important tool for the determination of hop chemotypes, ecotypes or evaluation of hop quality (Katsiotis et al. 1990).
There are many forms of wild hops, which are similar according to their composition, so it is very difficult to distinguish between various ecotypes or phenotypes. In 1926, a collection of hops was created at the Kaunas Botanical Garden of Vytautas Magnus University by K. Grybauskas, where many wild forms and different varieties from Western and Central Europe were collected for scientific investigations and nurturing of new varieties. Hybridization between the climate and plant illness resistant wild forms and highly productive, but less resistant domestic varieties was carried out. Based on that, five new Lithuanian hop varieties were nurtured (Obelevičius 2003). Combination of modern instrumental analysis and chemometric methods provides a possibility to classify various chemotypes of plants, revealing differences of chemical composition of their secondary metabolites. Unique situation, when plants have been cultivated at the same collection (identic edafoclimatic conditions), provides a possibility to focus exclusively on the genetically resulted chemotyping, whereas comparison of several harvests shows the influence of hydrothermal conditions variation on the biosynthesis of secondary metabolites in plants. Over 170–200 compounds can be separated and their quantities estimated using capillary GC analysis of hops essential oils in one run, which is a very suitable tool performing comparative study of different plants by so called chromatographic profiling or fingerprinting (Stankevičius et al. 2007). Evaluation of those results by chemometric methods not only reveals the information analogous to that obtained in genetic analysis, but provides phytochemical composition data, which are indispensible for standardization and quality control of plant raw materials required in food or pharmaceutical industry. High resolution and ability to provide precise and accurate qualitative and quantitative data distinguishes GC-MS analysis as valuable tool for taxonomic studies of plants.
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