Comparative analysis of four hop cultivars grown in Brazil and the USA by GC-MS-based metabolomics

Why was the work done: Although the third largest beer producer in the world, Brazil currently imports the majority of its hops. A recent development is the cultivation of hops (Humulus lupulus L.) in Brazil. In addition to genetic factors, the chemical composition of hops can exhibit variations due to conditions of cultivation. Accordingly, it is of value to characterise and differentiate hop cultivars grown in Brazil with the same cultivars grown in a long established location such as the United States of America. How was the work done: Centennial, Chinook, Columbus, and Nugget cultivars grown in Brazil or in the USA were compared by metabolomic analyses of the chemical profiles using gas chromatography coupled to mass spectrometry. Principal component analysis showed sample grouping according to where the hops were grown. Partial Least Squares Discriminant Analysis allowed the characterisation of the main metabolites that discriminated hop samples from the two countries. A total of 31 metabolites were putatively identified, including monoterpenes, sesquiterpenes, oxygenated mono- and sesquiterpenes, esters, alcohols, and ketones. What are the main findings: There were clear metabolic differences between the same hop varieties grown in Brazil or the USA. The metabolites with the greatest discriminating power for Brazilian hops were trans-α-bergamotene, 2-decanone, and ι-gurjunene, while American hops presented β-copaene, humuladienone, and isopentyl isobutyrate. Notably, trans-α-bergamotene was present in Brazilian hops but absent from American hops. Why is the work important: This study sheds light on the differences in the chemical composition of hops cultivated in Brazil compared those cultivated in the USA. This knowledge may stimulate new producers and contribute to the development of hop cultivation in Brazil.