Determination of the Geographical and Botanical Origin of Hops (<i>Humulus lupulus</i> L.) Using Stable Isotopes of C, N, and S

Abstract

A need exists for a reliable method to determine the geographical and botanical origin of hops. For this study, three sets of samples were collected: the first set comprised 5 German samples; the second set comprised samples of hops from 10 of the world's major hop-growing regions; and the third comprised the 4 main Slovenian regions. The samples were analyzed using isotope ratio mass spectrometry (IRMS) to obtain δ¹³C, δ¹⁵N, and δ³⁴S values. The δ¹⁵N (2.2 ‰ to 8.4 ‰) and δ³⁴S (0.7 ‰ to 12.3 ‰) values were the most discriminating parameters for classifying hop according to geographical origin. ANOVA showed distinct groupings for 8 out of the 10 hop-growing regions. Although it was not possible to distinguish the geographical origin of hops based on δ¹³C (-28.9 ‰ to -24.7 ‰), in the case of botanical origin, δ¹³C values proved to be the most discriminative albeit with limited success.