Wednesday, February 29, 2012
More Aroma Oil, Faster: The Dry Hopster’s Holy Grail
OSU tests IH pellets vs Cones for aroma intensity and oil extraction rates
OK. OK. You want more aroma. Do you dry hop with whole cone hops, or pellets? And how long? You’ve got limited capacity. Do you dry hop for a week, or something less than that?
Questions. For answers, where do you turn? A textbook? A magazine? Your buddy? The BA message forum? Google? Or do you just wing it?
We tried all of the above, but decided the questions were serious enough to warrant serious study utilizing the scientific method and the best available technology.
In short, we called Peter Wolfe and Dr. Tom Shellhammer at Oregon State University. They spent a year researching the questions. It’s pretty interesting, even for a liberal arts guy like me. In fact, it’s fairly startling.
We won’t post the study here, as it has not yet been published. But, for details, give us a call, and we’ll give you a closer look at the data. For now, here’s a summary.
* A 10 member sensory panel evaluated the intensity of dry hop aroma from Cascade pellets and whole cones and concluded that the pellets provided more intense aroma.
* Beer samples dry hopped for one day had significantly more aroma than beer dry hopped for 7 days.
* Irrespective of form (pellet or whole cone), the concentrations of hydrocarbon terpenes (eg, myrcene, humulene and limonene) peaked between 3 and 6 hours in dry hopped beer and then declined, while the concentrations of terpene alcohols (e.g, linalool and geraniol) continued to increase throughout the 24 hour dry hop extraction.
A few caveats.
First, not all pellets are the same. The pellets used for this study were supplied by us, Indie Hops, and we’ve previously shown that our pellets are different in terms of the average particle size, the diameter and the “bakedness” (our grist is extruded at between 106F and 115F).
We’re gratified to learn that our pellets produced about twice the intensity of aroma than whole cones. That’s huge! The conclusion reinforces what common sense told us: nature designed the hop flower to keep the oils “in”, not let them out, while IH pellets were designed by guys who wanted to get the oil “out.” We deliberately designed our mill to chop up the cone in bigger, coarser particles so that we could open up without pulverizing the oil-exuding lupulin glands.
Second, the rapid extraction rates were likely influenced by the temperature of the solution (23.3C, which may not be representative of real world conditions), and the hops were continually stirred. Although there’s been ongoing anecdotes and discussion about methods for agitating or recirculating/re-entraining hop grist in the tanks, we don’t have a reasonably available tried and true technology for re-suspending hops during dry hopping.
The research suggests, however, that the machinery needed wouldn't be too terribly difficult, and it only need to engage for a few days.
Third, the sensory panel consisted of 10 trained beer geeks who measured the aroma intensity on a scale of 0-15 based on the smell, not taste. To quantify the aroma compounds extracted (e.g., linalool, myrcene, etc), as well as the extraction rates, OSU used all the usual hi-tech stuff.
The take home: if you don’t have a torpedo, prefer (IH) pellets over cones, don’t have limited tank capacity and like big oily aromas, you’re not measurably losing anything, other than lore points, by not using whole cones.
And if you really love big oil, keep noodling and tinkering with new ways to keep those pellets circulating. And if you really love big oil but aren’t big, if you can keep those pellet particles suspended, you might also be able to save money by shaving 3-4 days from the standard dry hop schedule.
In the meantime, we’ll keep asking the questions.
The name of the unpublished manuscript is: “Dry Hop Aroma Extraction and Sensory Evaluation Report on Phase II dry hopping experiments,” by Peter Wolfe and Thomas H. Shellhamer, Ph.D, Dept. of Food Science and Technology, OSU, Corvallis, Or. (1/2012).
Note: Check out these Guth Portable Agitators used for mixing, stirring and homogenization of liquids such as wine. Could the same technology be modified for use in agitating hops during dry hopping?