For as much time as brewers spend talking about hops, you'd assume we know all about them. The bizarre reality is that we know surprisingly little about how hops work, what they add in terms of flavor, and the effects of different treatments and manipulation of them.
Don't believe me? Spend some time digging into the scientific research into hops. You'll soon start wondering about the competence and sanity of the brewers who never miss a chance to talk up their hopping process, their proprietary hops and blends, and how they use X hop to get Y flavor. If we know so little, they must be completely snowing and bullshitting us. How dare they!
That's right - you heard it here first. I'm calling out ALL professional and home brewers and saying they're all LIARS!
No, not really (though I'd love to stop the post there and see what kind of reaction we get). They're not lying. They're probably not even wrong. It's just that hop usage and what comes out of it is super-idiosyncratic: if the non-lying brewers in question produce similar recipes with changes in hop type and/or use, they can dial in flavors they want. What we shouldn't do is necessarily assume that what works for that brewer will work the same way for us, because there's a very good chance it won't.
Today's offering will (at least attempt to) provide some actual translatable lessons that can put up some signposts on the solipsistic road that brewers find themselves on when it comes to hops.
I'm an intense advocate for blending your hops. Single-hop beers are all well and good, and have the virtue of taking the guesswork out of where hops-derived flavors are coming from in a particular beer, but their utility is limited for recipe and even for education purposes.
You're not getting a general impression of one hop - you're getting one impression of one hop, since the point of addition, length of whirlpool, water chemistry, yeasts strain, grist, and more are creating a unique flavor and aroma. Hell, that specific batch of hops and its oil ratios matter, too, both in terms of how it presents and what compounds are created when its added and fermented-on. And as for single-hopping for recipe purposes, you're putting all of your flavor/aroma eggs in one hop basket, which is risky since we know that other process and recipe elements can scrub out flavors from a hop that you presumably chose for its flavor profile.
Instead, I recommend pairing hops for better results, at least if you're not willing to put in the repeated-batch-brewing necessary to find effective single-hopping (remember, you'll need to find out for yourself how that hop presents in YOUR beer in THAT recipe). You can either pick hops with complementary flavors (for example, I love the Hallertau-Northern Brewer combo for its woodsy and floral presentation) or those that amplify common flavors (say, Citra and Motueka for a big-time citrus and tropical fruit bomb). Consult a good hops flavor chart, and pick hops that work well for your target recipe, knowing that even if you don't get all of what you wanted, you're at least covering your bases.
Ignore IBUs (a little)
Don't obsess over IBUs. What you should care about is the impression of bitterness you're getting, and especially if you aren't working your water chemistry that's going to differ substantially from one brewer to the next (and one recipe to the next, for the same brewer) even at the same IBU level.
Use an IBU target for the first time you brew a recipe, then adjust up or down based on impressions. It doesn't matter if your Ordinary Bitter only has 20 calculated IBUs instead of the guideline-minimum so long as it tastes like it does. By the same token, ignore the maximum if you're still getting an IPA that lacks a soft bitter burr on the palate.
You should also be looking for all sources of bittering impression in your recipes and aiming for a general "bittering impression" level. IBUs are certainly one source. So is carbonation level. So is the presence or absence of roasted malts, what Lovibond level they're kilned to, and whether they're husked or dehusked. So is sulfate-to-chloride ratio.
Don't think of bitterness just in terms of alpha acid percentage, boil time, and utilization.
When it comes to late hopping, you'll have lots of brewers tell you that the longer hops are in contact with hot wort, the less aromatic impact you'll get as volatile compounds in the essential oils disappear into the ether. They'll also tell you that whirlpooling will add isomerization "time" to your already-added hops.
There's emerging evidence that that isn't quite right. It's probably true when we're talking about boiling wort - as minutes go by you're creating more iso-alpha acids (bittering) and burning off essential oils. But it's not at all clear when it comes to hot-but-not-boiling liquid. Experimental research strongly suggests that long whirlpools/hop-backing yields a higher level of aroma from hops than shorter exposures, even though it means longer contact with hot wort.
So, when it comes to whirlpool hopping, take your time. Slow down. You'll probably get more flavor out of your hops while risking very little in terms of your mid-to-late boil hops.
You're Not Aging Your Hops
Finally, I field this question all the time, and I'd love to try to bury it here: no, you don't need to worry about how old your hops are. If you're taking any kind of care in the storage of your hops, then they're perfectly fine to brew with for at least a year, and probably longer.
Will the AA% be a little lower? Yes, probably. But not that much. And see the earlier note on not obsessing about IBUs.
To think, though, that you're going to get cheesy flavors, or dramatically less bittering, or significantly less aroma/flavor out of a hop that you've had in a zip-locked bag in the refrigerator is bordering on zymurgic paranoia. Have you ever seen/read about what it takes to make hops "age" for use in things like Lambics? It takes some rough treatment; we're talking 50 Shades of Perle rough (Editor's Note: that's an absolutely killer and hilarious multi-level play on words as long as you're pronouncing it right - "Per-LAY").
So don't worry about your hops. I store mine in a bag with the air pressed out, zipped, in the freezer. They're basically immortal. (Second Editor's Note: This was TOTALLY written before Brulosophy dropped this week's exBEERiment!!!)
Try then Trust
There may be more, but that's all we have time for this week. Feel free to add questions/comments and expand! What's important, though, is that when it comes to hopping you keep good notes on use and subsequent impressions. There are rough rules to abide by, but to really get the most out of your hops, YOU need to be on the ball to find out what that looks like in your situation.
Try, then trust.
Keep it simple.