Some hop varieties appear to pack more flavor than brewers have traditionally recognized, according to a food science expert.
Essential oils within hop cones have long been known to impart flavor to beer, said Tom Shellhammer, food science professor at Oregon State University.
However, the cones also contain “flavor precursors,” which are water-soluble components that don’t manifest themselves until the brewing process, he said.
These compounds are bound to sugars in the hop cone, but yeasts break this bond and release the flavor molecules, Shellhammer said.
The “conventional wisdom” is that hops and other plants produce oils and acids to defend against pests and attract beneficial insects, he said.
Some of these compounds are bound with sugar in the water-soluble form so they can be moved within the plant more easily.
These compounds also happen to have sensory attributes, imparting flavors like citrus, ice tea, earthy mushroom, meaty broth and hay, Shellhammer said.
The brewing process releases these compounds into beer, though how much extra flavor is contained in water-soluble form depends on the hop variety, he said.
“Columbus” and “Centennial” hops seem to have particularly high reserves of such flavor precursors, Shellhammer said.
As brewers better understand the role of these compounds, they can serve as a tool to “bump up” the aromas from hops, he said. The knowledge may also be useful in breeding new varieties.