THE EFFECT OF VARIETAL CHARACTERISTICS AND WEATHER FACTORS ON THE FORMATION OF ALPHA AND BETA ACIDS CONTENT IN AROMATIC AND BITTER HOP VARIETIES

The stability of the quality characteristics of brewing hop varieties under conditions of climate change that effect on the accumulation of bitter acids and the formation of beer’s technological properties that is important for both producers and brewers. The aim of this study was to determine the impact of varietal characteristics and weather factors on the formation of alpha and beta acids content in aromatic and bitter hop varieties in the Zhytomyr region of Ukraine. Studies conducted from 2012 to 2022 established that the average alpha acids content in the cones of aromatic hop varieties was 4.0% and in bitter hop varieties was 7.7%, while the beta acids content was 4.9% and 4.8%, respectively. Inter-varietal differentiation was observed: among aromatic varieties, the highest accumulation of alpha and beta acids was characteristic of the Zagrava variety (5.4% and 6.2%) and the minimum was characteristic of the Klon 18 variety (2.5% and 3.3%); among bitter varieties, the highest values were found for the Ruslan (8.5% and 6.0%) and Xantha (8.6% and 5.6%) varieties and the lowest for the Promin variety (6.0% and 3.7%). It was established that the content of alpha acids is characterized by greater variability across the years of the study (Vp = 9.4–24.0%) compared to beta acids (Vp = 9.8–16.1%), that indicates their greater sensitivity to weather conditions. During the research period, the dominant influence of genotype on the formation of alpha acids content (53.2–66.3%) and beta acids content (67.1–72.0%) was demonstrated, while the contribution of weather conditions ranged from 12.4% to 20.9% and the interaction between varietal characteristics and weather conditions ranged from 17.5% to 32.4%. It was established that beta acids are characterized by higher genetic determination and stability, while alpha acids are more dependent on weather conditions during the growing season. The ratio of beta acids to alpha acids across the years of the study corresponds to typical ranges for the respective variety groups, with average values of 1.29 for aromatic varieties and 0.63 for bitter varieties, confirming the possibility of using this indicator as a criterion for the technological evaluation of hops. The most adaptable varieties were Zagrava and Ruslan, which combined high levels of alpha and beta acids accumulation with low variability across years. The study results provide valuable information on the characteristics of alpha and beta acids content formation in hops depending on genotype and weather conditions, which is the basis for predicting the quality of brewing raw materials.