Chemical characterization of the two major hop varieties produced in Patagonia (Argentina) for the brewing industry

Abstract

The yields and chemical compositions of the resinous and essential oil fractions vary in different hop (Humulus lupulus L.) varieties and in different environmental conditions. South American hop crops with most of the production located in North Patagonia (Argentina), have not been thoroughly described. The two main varieties grown in this location are Cascade, widely used for aroma purposes and Nugget, a high alpha variety. To characterize the Patagonian hop products, the essential oils and resinous components of dried hop cones and pellets were analyzed. Both cones and pellets showed low HSI values indicating "freshness" of the samples. Argentinian Cascade alpha-acid levels and the ratio of alpha to beta acids (alpha/beta), were above or in the upper range of Cascade typical values. For Patagonian Nugget, alpha- and beta-acid values, as well as the α/beta ratio, were within the range reported for other producing regions. As expected, essential oil yields were higher for the Nugget variety compared to Cascade (1.9 % and 1.0 % respectively); with both varieties high in myrcene (> 50 %). The α-humulene to beta-caryophyllene (H/C) ratio values were typical for these varieties as well as the amounts of the main essential oil components, including a high proportion of (E)-beta-farnesene in Cascade. Geraniol, nevertheless, was found in low amounts in Cascade; though two of its esters were present. This work indicates that hop varieties Cascade and Nugget appear well adapted to Patagonian growing and production conditions, producing high quality hop products. Future experiments to unveil the impact of the observed differences are of interest; including sensory analysis of beers hopped with the Patagonian terroir varieties compared with those from high producing regions.