Touted as the equivalent to a commerical brewery's "whirlpool" addition, many homebrewers have been adding copious amounts of hops at the end of their boils in an attempt to mimic the hop character found in their favorite, hop forward ales. Truth be told, I've always been underwhelmed with these additions in my homebrew creations. I have never been able to achieve acceptable hop aroma from this addition alone. I've always felt the late hops have been wasted to some degree. Question is, why do commercial whirlpool hops give such killer aroma and flavour but my addition does little? The answer is time and volume.
Many homebrewers, including myself, follow a flame-out routine something like - flame off, hops in, chiller on. Given the standard batch size and chilling equipment, our wort temperatures drop to below 140F in 5-10 minutes, pitching temperature in under 30 minutes. When dealing with commercial volumes, chilling this fast is near impossible. So, is the aforementioned flame-out routine really all that similar to a commercial whirlpool? No, not really. A commercial whirlpool can last 10 minutes or more before centrifugal force does its thing clears the wort from break and hops. The spinning wort is allowed to slow and is then finally pulled through a chiller on-route to the fermentation tanks. Remember, they're not dealing with a measly 10 gallons, we're talking several hundred if not thousands. An hour or more might pass during these transfers, all the while whirlpool hops are exposed to hot wort.
While reading Northern Brewer's discussion board a few months ago, I stumbled across a discussion on Hop Stands. The idea is rather simple. Add your flame-out hops and allow them to steep in the hot wort for an extended period of time before beginning the chill. On the surface it would seem reasonable that this step would more accurately mimic the commercial whirlpool. Read the thread and you will find varying opinions on how to correctly perform a hop stand. Some advocate lowering the temperature of the wort slightly before adding the flame-out hops to ward of DMS. Others suggest the lower wort temperatures will minimize the amount of hop oils flashed off. Certain hop oil will flash off at 100F, which would explain why Dry-hopping is so effective. Most agree the longer the hops are steeped, the better (infection risk be damned!), some advocating as long as 80 minutes! Well, I'll tell you, this better be some damn awesome aroma to warranty extending the brewday by 1.5hrs.
Having performed a hop stand now on two separate brews, I can tell you that I haven't been impressed. I actually feel the aroma may be diminished! Certainly not worth the extra time. There could be a number of explanations for my failure, first and foremost, what does the hop stand do to my early and middle additions? An addition at 60 minutes will have stayed in the wort for near 2.5hrs. Your 15 minute flavour addition may now impart more bittering type qualities. The Northern Brewer discussion talks about shifting these additions to later in the boil. I don't know... the unpredictability of variables introduced by the hop stand, not to mention the extra time and diminishing returns, far out way the benefits. In fact, I've started thinking about my final addition and believe I might go in the opposite direction, increasing the boil time slightly and chilling as quickly as possible. I mean, why not embrace the advantages of the home brewery? We can chill and rack wort in less than 30 minutes! This type of efficiency must certainly be the envy of the commercial brewer.
I read a cooking analogy and thought it very appropriate. Hops are the spice of beer. When cooking, many spices must be heated or simmered to bring out aromatic scents (oils). With cooking in mind, perhaps the key to aroma is to quickly boil the hops, flashing the oils. The boiling action will further aid to solubilize the oil into the wort, once complete we quickly chill to below flash temperature, thus locking in the flavour?
In my previous article, I more or less completely wrote off the 30 minute addition as a supplementary bittering addition and some what redundant. Lately however, I've come across discussion on hop Glycosides, Polyphenols and the benefits. Warning, lots of scientific stuff! To summerize
"The main effect of polyphenols on flavour stability isprobably situated in the mashing and wort boiling steps(Liegeois et al., 2000; Mikyska et al., 2002). In particular,polyphenols extracted from hop during wort boilingsignificantly contribute to the reducing power andeffectively diminish the nonenal potential of wort (Lermusieau,Liegeois, & Collin, 2001). Sensory experiments(Mikyska et al., 2002) also confirm the positive effects ofhop polyphenols, during brewing, on flavour stability.."Further reading has described the benefits as a roundness of flavour, body, and general hop character. It's agreed among many experienced brewers that the 30 minute addition is best to promote these mysterious reactions.
For the next few beers I am going with a 60-30-12-3 hopping schedule and will report back on how they turn out.