Hops are the cone-like flowers of the female hop vine, and are used to balance the sweetness of the malts with the bittering qualities of the hop resins. When brewing with kits, the homebrewer doesn’t have to worry about hops since they are already present in the kit itself. As soon as the brewer begins using recipes, however, s/he must begin to learn how to buy, use, and store hops.

Terminology

Although hops are indeed used primarily for their bitterness, they are also frequently used both for their aroma or bouquet, as well as for their flavour. These 3 main uses give us the 3 common general terms used when referring to hops :

bittering hops a.k.a. boiling hops
flavour hops
aroma hops a.k.a. finishing hops

The above terms don’t actually refer to varieties of hops as such, but rather to how the hops are used. Just about any variety of hop could theoretically be used for any of the above three purposes, although there are indeed certain varieties which are best suited to one specific task, and others which aren’t so well suited to another. In general, when hops are boiled for 45 to 75 minutes, they add bitterness to the beer. Hops boiled for 15 to 30 minutes add the flavour of the hops to the beer, while steeping them for 2 to 10 minutes (or boiling them for 1 to 5 minutes) allows the hop aroma (bouquet) to come through.

Another couple of buzz-words one often hears in relation to hops are the terms noble hops and high-alpha hops. Noble hops are those earlier varieties which have traditionally been used in various styles of beer in some of the great brewing nations. German Hallertau, Czech Saaz, British Fuggles and (former) Yugoslavian Styrian are all examples of Noble hops. For a full listing see the hop table on this page. Noble hops can generally be used for bittering, and are often prized for their aromatic characteristics. Also, they are typically lower in alpha acid content, usually around the 4% to 6% range.

As brewers began to better understand the role of hops in their beer, varieties began to be developed which were much higher in alpha acid content, thus requiring less hops for the same level of bitterness. Thus we have such high-alpha hops as Brewer’s Gold, Eroica, and Northern Brewer.

Finally, one often hears mention of a hopping schedule. This is simply a term used to describe the intervals at which hops are added to the boil while making a particular recipe. For example, one of our favorite India Pale Ales requires an addition of Northern Brewer hops at the beginning of the boil (boiled for 60 minutes), and another addition of Cascade at the end of the boil (steeped for 5 minutes). This is our hopping schedule for that recipe.

Bitterness

As stated above, hops are used by brewers primarily for their bittering characteristics. This bitterness comes from resins which contain humulone (a.k.a. alpha acids) and and lupulone (a.k.a. beta acids), which are found (along with the aromatic oils) in little yellow sacks called lupulin glands, found on the petals of the flower. Most good suppliers package their hops with a number on the package indicating to the homebrewer the percentage of alpha acids by weight of the hops. Since alpha acids are responsible for 90% of bitterness, and since beta acids don’t disolve well in a normal wort 1, the percentage of betas is of little or no importance to the brewer.

The alpha acid content, on the other hand, is of vital importance to the homebrewer since it is the only way she can know exactly how much bitterness is being added to the beer. It should furthermore be noted that not only do the numerous varieties of hops vary immensely in their alpha acid content, but the percentage of alpha acids found in the hops produced by a single plant can vary from year to year by as much as a few percent, depending upon condtions. Brewers should therefore be wary of purchasing hops which do not have the alpha percentage clearly marked on the package. Although most repackagers supply this information nowadays, there are still a few who for whatever reason do not. One notable exception here is for home-grown hops. With these we usually brew a test batch assuming the % alphas of the hops to be right in the middle of the range for that variety, then after tasting the final beer it is fairly easy to make appropriate adjustments for subsequent batches.

Selection

When choosing the proper type of hops for a beer, the homebrewer must take a number of factors into consideration. First and foremost, if a particular style of beer is being brewed, then the proper hops must be chosen to suite the style. For example, for a Bavarian Wheat beer, Hallertauer, Tettnanger or even Saaz hops would be chosen.

Of course, one of the obvious advantages of being a homebrewer is that one is free to do whatever one wants with the beer, so these guidelines don’t have to be followed exactly to the tee. With a bit of an understanding of hops and hop specifications, the brewer is of course free to make substitutions. For example, both Liberty and Mt. Hood are U.S. hop varieties which were bred to resemble Hallertauer, so either of these could be used in the aforementioned Wheat Beer.

It must be stressed, however, that hop substitution should not be done blindly. The brewer should have an idea of what he is doing, as well as what sort of effect the substituted hops will have on the beer. Most importantly of all, we must emphasize that hops cannot simply be substituted on an ounce for ounce basis. With this in mind, we introduce one of the methods used to determine exactly how much hops to put into one’s beer.

All but the very most advanced of homebrewers use a number known as an AAU (alpha acid unit) or HBU (homebrew bitterness unit) to determine how much hops to put into their beer. Both of these terms are synonymous, and have a direct relation to the percentage of alpha acids in the hops. Stated simply for the record, very advanced brewers use the IBU (international bitterness unit) scale, which must be computed using a very complicated formula which takes into account wort volume, wort gravity, alpha acids, as well as a number of other factors including the ever-nebulous utilization effeciency, which accounts for the particular way in which the brewer is boiling the wort.

Most recipes we see in books and elsewhere call for a certain number of HBU‘s (or AAU‘s) of a certain type of hop. For example, a Bavarian Wheat beer recipe might call for 6 HBU‘s of Hallertauer hops to give it the proper bitterness according to the style. So how do we translate this number into the number of ounces of hops required? Quite easily, as fortune would have it.

Let’s say the hops we just purchased at our favorite brew store states there to be 4% alpha acids by weight in these hops. So this means that one ounce of these particular hops will give our beer 4 HBU‘s. So in order to get the 6 HBU‘s the recipe calls for, we need 1.5 ounces of hops (4% alpha x 1.5 ounce = 6 HBU‘s).

But suppose you give the same recipe to a friend, who bought her Hallertauer hops elsewhere. Her package states that her hops are 5% alpha. So 1 ounce of her hops will yeild 5 HBU‘s to the beer, so she’d want 1.20 ounces of these hops. In this situation, we’d almost certainly use 1.25 ounces, since a quarter ounce is easier to measure out without a scale than a fifth of an ounce. Sure, that will overshoot the specified amount by just a bit, but there’s always room for a bit of variety in homebrew. If you really want to pick nits, weigh your hops out exactly on an accurate scale so that you get precisely 6 HBU‘s. Keep in mind, however, that the very nature of HBU‘s themselves means that there will be some varience between brewers, so being totally accurate with your weights probably isn’t going to mean she’ll get exactly the same bitterness, anyway.

Suppose even further that a second friend liked this beer so much that he’d like to brew it, too. He doesn’t have any Hallertauer hops on-hand, but happens to have a few ounces of Saaz kicking around in the freezer which are marked as 3.0% alpha. Since Saaz is also used in some Bavarian Wheat Beers, your friend is remaining within the style, but will have to use 2 whole ounces in order to get the 6 HBU‘s specified in the recipe. This is an example of using a bit of hop-knowledge to make substitutions in a recipe, yet still remain within the style.

Forms

Another important consideration when selecting hops is what form it is in. The 3 most common forms of hops are pellets, plugs and whole. Whole hops are sometimes referred to as “Leaf” hops, and they are the least processed form available to the homebrewer. These hops appear very similar to how they looked on the vine, except that they have been dried, and the cones separated into individual leaves. Plug hops are whole hops which have been compressed into 1/2 ounce plugs about the size of a golfball, but cylindrical in shape rather than spherical. One nice advantage of this form of hops is that they are so easy to measure – as long as you need even multiples of half ounces at least, otherwise this becomes a disadvantage. In the brew kettle plugs quickly separate into individual leaves and so they behave in the kettle exactly as leaf hops. Pellets are processed even further than plugs – first they are ground up and then pressed into tiny pellets resembling rabbit food. The way they have been processed means they expose less surface area to the air, and thus have less of a potential to go bad. This applies to plugs as well as vacuum sealed leaf hops. And if stored properly in the freezer the difference should be negligible.

Another thing to keep in mind about pellet hops is that the fact of their processing means they often give more of their bitterness to the beer, and do so in a shorter period of time in the boil. Many homebrewers feel they get full hop utilisation from pellet hops in only 45 minutes vs 60 minutes for plugs or whole. The exact amount of extra bitterness you get from pellets does not seem to be well documented, but figuring with about 15% is probably safe.

Both whole and plug hops have their own advantage in the kettle as well. If using a manifold, gooseneck or some other means of filter in the kettle, these hops act as an excellent filter medium which helps leave break material behind in the kettle. Pellet hops on the other hand have been known to actually clog these sorts of devices because they have been so finely ground up before being formed into pellets. However, the addition of even a small amount of leaf or plug hops along with pellets can alleviate this problem. For exactly the same reason, pellets also do not work very well in a Hop Back.

Usage

As we already know, hops are used for bittering, flavour, and aroma. The only way to get the hop resins to dissolve into your beer wort (isomerize) is by means of vigorous boiling. To get maximum bitterness from your hops, they should be boiled for 45 to 60 minutes. To get hop flavour into your beer, boil for 15 to 30 minutes. Finally, to get the wonderful hop bouquet, boil your hops for no more than 5 minutes, or steep them after the boil for 2 to 10 minutes.

Storage

Even if you are never going to have hops leftover from your brewing session, you should still know a bit about proper storage. Without this knowledge, you could very easily end up purchasing hops which have gone bad due to improper storage. As unbelievable as it may sound, there are still plenty of retailers out there who haven’t a clue about proper hop storage, so the chances of getting bad hops are actually better than you might think — unless, of course, you happen to know what to look for.

There is one very basic requirement in storing hops : no oxygen. Depending upon how this requirement is met, there is a secondary requirement : low temperature. One other tidbit of information that is extremely important to note in this context, is that plastic allows oxygen to pass through it, albeit slowly. So right off the bat you can forget about the loose, whole hop leafs that you often see on supermarket shelves packaged in an unsealed plastic bag which has been merely stapled shut.

Most packages of hops we buy these days come vacuum-sealed in foil. Any reputable reatailer will keep them stored in a refridgerator, which is exactly where you should store them once you get them home. A newer packaging process that one sees a lot of these days involves sealing the hops in a foil bag in which all air has been replaced with nitrogen. This apparently nullifies the need to keep the hops in cold storage, so don’t turn up your nose if you see them on the shelf of your favorite homebrew shop. Indeed, the hop plugs which we find locally come in just such a package, and are by far the freshest and most aromatic hops we’ve ever used, even though the retailer doesn’t keep them in cold storage.

Once the package has been opened, though, great care must be taken to keep them away from the air, and nice and cool. The best way to do this is to roll them up in their foil bag, place that into a ziploc freezer bag, suck out all the air (vacuum sealers work like a charm), then put the first ziploc bag into a second one, suck the air out of it and put it into the freezer. Experience has show us that without the double-bag, the whole freezer ends up smelling like hops, which conversely means that your hops end up tasting like the rest of the contents of the freezer. But with this simple double-bagging method, hops can be kept fresh for months on end. Just make sure that you store only 1 type of hop in each bag, and label the package well both with the hop variety, the alpha acid content, along with the date when the original package was initially opened.

If you’d like to be even more picky about your hop storage, many of the better retailers are beginning to stock oxygen barrier bags for storing hops at home. Using these instead of the double freezer bag will give you an extra bit of security in hop storage.

Varieties

Name Comment Alpha
Cascade Aroma 4.5 – 7
Centennial Bittering 9.5 – 11.5
Chinook Bittering 12 – 14
Cluster Bittering, Cascade bred as replacement 5.5 – 8.5
Crystal Aroma 2 – 4.5
East Kent Golding Noble,Aroma,several subtypes exist 4 – 5.5
Eroica Bittering 11 – 13
Fuggles Noble,Aroma 4 – 5.5
Galena Bittering 12 – 14
Hallertauer Noble,Aroma 3.5 – 5.5
Hersbrucker Noble,Aroma 3.5 – 5.5
Liberty Aroma, US approximation of Hallertauer 3 – 5.5
Mt. Hood Aroma, US approximation of Hallertauer 5 – 8
Northern Brewer Bittering 8 – 10
Nugget Bittering 12 – 14
Perle Aroma 7 – 9.5
Saaz Noble,Aroma 3 – 4.5
Spalt Noble,Aroma 3 – 6
Tettnanger Noble,Aroma 4 – 5
Willamette Bittering 4 – 6

 

Substitutions

This section is under construction.

In generally, the very first thing you are worried about in substituting hops is the alpha acid content (AA). If your recipes calls for 2 ounces of Hallertauer at 4.5%, that makes a total of 9 AAUs (alpha acid units). Now if all you have is Liberty hops at 6% AA, then you need 1.5 ounces of Liberty to give you 9 AAUs. Also in doing this you want to try to stay true to the beer style if at all possible. This means if it is a UK style beer you are brewing, then substitute only another UK style hops, or at very least a North American clone of one of the UK hops. Same goes for German beers and German hops and hop clones.

The table above has some of the information you need, stay tuned here for more.

 

Dry Hopping

Dry hopping is the practice of putting hops directly into the fermentor or keg. The practice yields an aroma and spicey flavour that is similar to late-hopping in the kettle, only more pronounced. It has been our experience that non-beer-geeks (i.e. your average Joe who doesn’t know Budweiser from Buddy Holly) absolutely love dry-hopped beer.

There really isn’t a whole lot involved in doing this. Normally you want to add the hops to the secondary fermentor, because if you add it during heavy fermentation the excaping CO2 will scrub out most of the aromatics that you put the hops in for in the first place. So it would be rather counter-productive. Just take them out of the package and throw them in. That’s it.

We’ve found that the best types of hops for dry-hopping are the noble hops, or other low alpha hops which have good flavour and aromic properties. You probably wouldn’t want to use any of the high-alpha hops which can have fairly abrubt and abbrasive aromatic characteristics. We also prefer the use of whole or plug hops for dry-hopping, because they tend to float on the top which helps protect your beer from infection. Though we do know that lots of people use pellets with great success. We’ve found that you need 1 ounce or more to get a really nice hoppy flavour and aroma in the beer. Leave them in the secondary for a good couple of weeks. When it comes time to siphon to your bottling bucket, putting a copper pot scrubber over the end of your J-tube will help keep the hops from clogging up the works during syphoning.

If you keg your beer, you can toss the dry hops right into the keg. If you do this we recommend affixing a copper pot scrubber to the end of the long dip-tube, to help keep the hops from getting sucked up into the dispensing tubes. Leaf hops tend to float on top, so you aren’t going to have a problem with those until the keg starts to get empty. Using the pot scrubber helps a great deal we’ve found, no matter what type of hops you use, or how full the keg is.

Some people recommend steaming your hops first before dry-hopping with them. They do this out of fear of infection. The fact of the matter is, however, that hops are naturally antiseptic. In fact, one of their key functions in beer is as a preservative. As such we feel that this risk is highly overstated, and we continue to just throw the hops in with no ill effects. In fact, often we’ll dry-hop a beer with leaf hops if we think it will be sitting around in the secondary for an extended period. The hops float on the top and help keep the nasties out. At the time of this writing we’ve got a Pale Ale in the secondary at room temperature now for over 7 months (boy, are we lazy). The dry hops are floating on top, protecting it from an infection.