Stability of aroma and bitterness compounds of Fuggle hops grown in subtropical conditions across successive harvests

Abstract

This study evaluated the stability of hop aroma and bitterness compounds in Fuggle hops cultivated in Brazil under subtropical conditions across three consecutive harvest years (2021, 2022, and 2023). A randomized block design was used, with three treatments (years) and 10 replicates each, totaling 30 experimental plots. Essential oils were extracted from 25 g of dried hop cones, and alpha and beta acids from 15 g. Essential oils were analyzed by gas chromatographymass spectrometry (GC-MS), and alpha and beta acids were quantified by spectrophotometry. Five major aromatic compounds were identified: myrcene, (E)-?-farnesene, ?-selinene, ?-selinene, and (E)-caryophyllene, with only minor variations across years. No significant variation was observed in essential oils content (p>0.05) throughout the harvests. Alpha acid concentrations increased significantly from 2.659% in 2021 to 4.523% in 2023, representing an 41,21% rise that stabilized after the second year. Beta acid levels ranged from 2.02% to 2.87% but showed no significant differences. Overall, the phytochemical profile of hops, particularly the aromatic components, remained consistent over time. While alpha acids increased initially due to physiological maturity, both aroma and beta acid profiles demonstrated long-term stability, supporting the reliability of successive harvests for maintaining hop quality.