From Vol. 1, No. 4, September 2017
The first measure of a crop is yield. By rule of thumb, a new field should reach its full (yield) potential in Year 3. But there is another measure, and that is the quality of the hops coming out of those yards. Of course, there are factors beyond the plants themselves, because process (picking, kilning, packaging) comes into play. And what one brewer wants from a cone isn’t necessarily what another values.
Nonetheless, research by Suntory Beer in Japan focused on Saaz hops likely has implications for other varieties. Dr. Takako Innui presented the results at the 2017 International Brewers Symposium on Hop Flavor and Aroma in Beer. Among other variables, the study measured the impact of root age.
Thirty-five percent of the Saaz plants grown in the Saaz region of the Czech Republic are 20 years old or older – an age at which, Innui said, the amount of linalool (one measure of aroma quality) will slowly begin to decline. Only 4% are 15 to 19 years old, so as new ones replace the oldest the over 20 population will decrease. Otherwise, 16% are less than 5 years old, 21% between 5 and 9, and 24% between 10 and 14.
The researchers analyzed hops both on their own and in brewing trials.
They found that the younger hops, particularly less than 3 years old, had more luxuriant vegetative growth and were late flowering. These contained lower amounts of monoterpenes associated with floral, fruity and citrusy aroma and flavor. They also contained more sesquiterpenes that contribute to sylvan (woody) character. As a result, beers brewed with them were less floral, fruity and citrusy.
A similar study focused on American-bred with higher levels of, say, geraniol or various thiols might well yield different results. But this certainly suggests that the composition of compounds within hops change as the plant matures, particularly in the first three years.
So it shouldn’t be surprising that as production of a popular variety ramps up to meet demand that some brewers and drinkers suggest it might be different than the year before.