Evaluation of variability in alpha and beta acid content in European hop varieties (Humulus lupulus L.)

Between 2009 and 2023, European hop varieties were evaluated within genetic resources in the Czech Republic. The objective of this paper was to determine the variability of hop alpha and beta acid contents in the monitored varieties at a single site over the period of fifteen years. At the same time, the trend in which the observed substances decrease or increase was assessed. The lowest average alpha acid content was detected in Strisselspalter (2.96% w/w), while the highest content was found in Herkules (14.03% w/w). The lowest variability in alpha acid content was measured in Vital (14.59%) and Herkules (16.48%). Unlike the aforementioned varieties, Golding exhibits the highest variability (46.28%). All varieties showed a decreasing trend in alpha acid content over the fifteen years of cultivation. Lubelski had the highest decrease in alpha acid content and also showed a high correlation (r² = 0.664). The varieties with the lowest average beta acid content were Celeia (2.77% w/w) and Golding (2.97% w/w). The variety with the highest average beta acid content was Vital (7.30% w/w). All varieties displaied a decreasing trend in beta acid content. Perle had the lowest trend of decrease in beta acid content, while Tradition had the highest trend of decrease. The varieties Strisselspalter, Saaz, Tettnang, Sládek, and Bobek had an alpha/beta acid ratio below 1. However, the variety Bobek showed the highest variability at 32.18%. Herkules had the highest alpha/beta acid ratio (3.20). The most stable alpha/beta acid ratio was found in Marynka (8.41%).