Varietal differences in the phytochemical components’ accumulation and aroma profile of three Humulus lupulus cultivars

Humulus lupulus (hop) cone is a key ingredient in beer, which determines its taste and aroma. The impact of ripening on the bitter acids, aroma compounds, and polyphenols of hops has been reported separately, there is no systematic study on all three components. Here, three hop varieties (‘TP1’, ‘TP2’, and ‘QTF’) in China were sampled to investigate the correlation between the harvest maturity and these three components, which indicated that polyphenols synthesized earlier than hop bitter acids, followed by the aroma compounds. Variety differences of the hop cultivars prompted the obvious separation in the partial least-squares discriminant analysis (PLS-DA). Among three hop cultivars. ‘TP1’ with the highest contents of aroma compounds contributed to flower aroma, and with higher contents of bitter acids which contributed to bitter taste. In contrast, ‘TP2’ has been reported to be rich in caffeic acid, salicylic acid, syringaldehyde, (+)-catechin, and (−)-epicatechin. To analyze the hop aroma characteristics, two matrices of hop tea and late-hopped beer were prepared and used for sensory evaluation. Compared to ‘TP2’ and ‘QTF’, the hop tea with ‘TP1’ scored best for ‘strong’ (P < 0.01), ‘herbal’ (P < 0.05) and ‘citrus’ (P < 0.01). While the ‘strong’ and ‘herbal’ characteristics from terpene compounds receded in the late-hopped beer, the ‘citrus’ and ‘fruity’ notes from terpenol compounds remained noticeable.