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O-31. Percent co-humulone in hops: Effect on bitterness, utilization rate, foam enhancement and rate of beer staling

Presenter: Val Peacock, Hop Solutions Inc., Edwardsville, IL.

In 1972, Lloyd Rigby first presented the idea that what made an aroma hop superior was the lower percentage of co-humulone, which leads to a more pleasant bitterness. There have been a number of works over the years on the subject, more agreeing than disagreeing, but the issue seems to be more of a personal choice. However, are there other issues the brewer should consider in deciding if low co-humulone hops are desirable? For instance, the utilization rate for cohumulone is significantly better than for n-humulone and ad-humulone, resulting in real cost savings. On the other hand, iso-cohumulone is only half as effective at promoting foam in beer as the other iso-humulones. In addition, iso-cohumulone degrades in beer much more quickly than the other iso-humulones. Loss of these iso-α-acids is directly related to the amount of stale flavor in beer. As a result, packaged beer will remain fresh longer with the use of low co-humulone hops. Cost factors would favor high co-humulone hops, while non–bitter-related quality factors all point to low co-humulone as being superior. The issue of the quality difference of bitterness must be determined by the individual brewer.

Val Peacock received a B.S. degree in chemistry from Iowa State University in 1973 and a Ph.D. degree in organic chemistry from the University of Wisconsin in 1978. He was a research associate at Oregon St. University, working on hop flavor in beer from 1978 to 1981 and 1987 to 1988. From 1981 to 1986, he was a research scientist for the Seven-Up Co. From 1988 to 1989, he was a research chemist for Redd Citrus, a firm manufacturing natural citrus flavors from waste streams from juice processing. From 1989 to 2008, he was the manager of hop technology for Anheuser-Busch. In 2009, he founded his own consulting firm, Hop Solutions Inc. (H.S.I.).