This blog post provides a summary of the techniques I’ve found for maximizing hop flavor and aroma, based on my experimental results and general experience. Others have said many of these things before, and in some cases with better writing skills. I am not claiming that anything here is a new discovery; I’m just reporting what I’ve found from my personal brewing experience. (As usual with this blog, the contents of this post may change over time as I revise and update what I’ve learned.)
1. Add Hops Late in the Boil. Like Really, Really Late
Hops should be added late in the boil. How late? That depends on when you start cooling your wort and how quickly it cools. According to Papazian (The Home Brewer’s Companion, p. 68), flavor is maximized at 10 minutes before flameout. I’ve found increased hop flavor by adding hops at flameout and then letting the wort cool naturally (with the lid on) for 10 minutes. There is a lot of room for experimentation here.
Also, according to Greg Noonan, “the bitterness derived from long boiling is coarser than that from a more moderate period” (Noonan, New Brewing Lager Beer, p. 154), which also suggests that more hops for a shorter time in the boil is advantageous.
It seems that boiling temperatures will decrease hop flavor if applied long enough (e.g. greater than 15 minutes), but it may also be that that (near) boiling temperatures are needed in order to bring out hop flavor.
2. Don’t Use Hop Stands for Long Periods of Time
Keeping hops in the wort at various sub-boiling temperatures for 60 minutes adds maybe some extra body, but little to no additional hop flavor. A 45-minute hop stand at 170°F seems to add no hop flavor. On the other hand, a 10-minute hop stand (with hops added at flameout) can produce very nice hop flavor. The take-away message seems to be that long hop stands (45 minutes or more) don’t add hop flavor; shorter hop stands (around 10 minutes) do, although temperature may also be a factor. Even at sub-boiling temperatures, steeping for too long removes (or fails to produce) that wonderful hop flavor. Are the sub-boiling temperatures of a hop stand beneficial to flavor, or do the flavor benefits come mostly from the amount of time of the steep? I don’t know.
3. Cover the Kettle After Late-Hop Additions
The effect is very small, but covering the kettle after late-hop additions (i.e. no greater than 10 minutes before flameout) may provide some increase in hop flavor. For hop-forward ales, there is minimal risk of high DMS levels caused covering the kettle for a few minutes.
4. Dry Hop for Aroma
I haven’t yet done any controlled experiments on hop aroma, but at this point I’ve found that small to moderate hop aroma requires a large amount of late-hop or flameout additions. But a big aroma can be obtained through dry hopping with an ounce or two (about 25 to 60 grams). (Noonan says it better: “the full, fresh aroma of hops is only captured by ‘dry-hopping’.” (Noonan, New Brewing Lager Beer, p. 78.)
5. Dry Hop using a Weighted Mesh Bag
When I dry hop with whole cones, I sometimes put the hops in a very large mesh bag along with some weights. The bag makes for easy removal of the hops, and the weights force all of the hops to be submerged. The large mesh bag allows the hops to move around in the wort. If you have a narrow-necked carboy, you should consider racking the beer to the keg or bottling bucket before removing the hops.
6. Dry Hop for Shorter Periods of Time
As Palmer notes, dry hopping may yield “a dry aftertaste, like old tea” (Palmer, How To Brew, p. 44). Strong comments that “it can produce a lingering grassy, vegetal note that some may not like” (Strong, Brewing Better Beer, p. 72). He recommends “limiting the contact time of dry hops in beer to 3 to 7 days” (ibid, p. 72). More to come on this topic, but a week of dry hopping is not too long, in my experience, as long as well-preserved hops are used.
7. Use a Lot of Hops Very Late in the Boil
When using too much hops there is the risk of tannins that can cause a grassy taste (Palmer, How to Brew, p. 44) and of course excessive bitterness. But big, hoppy beers seem to require (strangely enough) lots of hops. In a 5-gallon (19-liter) batch, six ounces (170 g) of hops very late in the boil (and/or at flameout) and an additional two ounces (57 g) for dry hopping is good, but maybe even on the low side for a really big beer.
Some beers that I’ve brewed with lots of hops do tend to have what I think is referred to as a “grassy” flavor, as noted by Palmer. It’s not necessarily bad, but it’s not the character of the hops that I’m looking for. At this point, I think that this flavor was caused by using improperly-stored hops. In a six-gallon (23-liter) boil, I’ve added one ounce (28 g) at 15 minutes before flameout, 11 ounces (312 g) at flameout (with 10 minutes of post-flameout natural cooling), and an additional 2 ounces (57 g) during dry-hopping, and not noted any grassy flavor (but lots of wonderful citrusy flavor). All of these additions were made with properly-stored hops, which may have been a critical factor. (In fact, that beer turned out quite well and measured only 41 IBUs.)
By adding lots of hops late in the boil, IBUs are difficult to predict using standard models. On the one hand, additions close to flameout will produce more IBUs than predicted by standard formulas because of continued heat after flameout; on the other hand, once you get above 2 ounces (57 g) of AA 10% hops in a 6-gallon (23-liter) boil, IBUs increase less than standard models will predict. The mIBU model addresses flameout additions but not high levels of alpha-acid concentration. A different post provides a hopping-rate correction factor that is linked to alpha-acid solubility. At any rate, I’ve learned to not fear large amounts of well-preserved flameout hops with a 10-minute rest period before forced cooling.
I’ve heard about, but not yet had time to try, the following techniques:
Hop Tea: Add a homemade “hop extract” or “hop tea” to the secondary. Noonan gives fairly detailed instructions (Noonan, New Brewing Lager Beer, p. 160) and recommends the practice.
Hop Bursting: Divide the flavor hops into several additions, with each addition made at a slightly different time. For example, instead of adding 2 oz of hops at 10 minutes before flameout, try ½ oz each at 15 min, 10 min, 5 min, and 0 min.