Evaluation of yield and alpha acid content in selected hop varieties

The stability of the agricultural and technological properties of hop varieties over the course of time and under changing climate is essential for both growers and brewers. This study is a typical case of monitoring 12 hop varieties selected from a collection of hop genetic resources, that were evaluated in the years 2009 to 2021. The assessed parameters were the hop yield and content of alpha acids with a focus on the variability/stability of this characteristics. Only the Pilgrim and Target hop varieties from England showed exceptional hop yield above 3 kg/plant. On the other hand, the lowest hop yield was obtained from the Saaz and Bramling Cross hop varieties, i.e. below 1.5 kg/plant. The lowest variability of hop yield - below 30% - was found in the Savinjski Golding, Bramling Cross and Saaz hop varieties. In contrast, the Bobek, Aurora, Pioneer and Phoenix hop varieties demonstrated the highest variability of hop yield, i.e. above 50%. Further, also Target and Phoenix have the highest content of alpha acids, namely 9.68% w/w and 9.56% w/w, respectively. The lowest content of alpha acids was determined in Saaz, which was the only hop variety with an alpha acid content below 3.0% w/w. The Premiant, Target and Aurora hop varieties exhibited a variability of alpha acid content below 20%. On the contrary, the Bobek and Pilgrim hop varieties had the highest variability of alpha acid content, namely above 30%.