Finesse. Exotic, complex, subtle, whimsical, boisterous, evocative. The small, wondrous flowerlike hop cone impassions many a brewer and beer enthusiast with so very little. At 8 milligrams (.00028 oz.!) per bottle of beer, the “stuff” of hops imparts all the wondrous character that beer enthusiasts have come to appreciate.
We know that hops contribute bitterness, flavor, aroma and stability to the beer and a calming effect to the beer drinker, though it appears that this calming effect is sometimes counteracted by an excitement about all things beer. Hopheads and lupomaniacs are often known to discuss life in terms of “the lupulin effect.”
If there is one principle to remember about hops and their use, it is that their freshness should always be considered. Fresh means that the hop has not gone stale, or become old or oxidized to a degree that negatively impacts the character of beer. Minimal oxidation or staling is desired of bittering hops. They are best at their freshest. However, some degree of aging and oxidation is essential for the best-quality aroma hops. Flavor-active components of the essential oils of aroma hops are low for fresh aroma hops. These flavors and aromas increase with about three to six months’ aging after harvest at ambient to cool conditions. There is some deterioration of bittering resin during this time, but a balance is determined and achieved by the skilled hop merchant.
Fresh does not imply freshly picked, nor does it imply whole hops rather than hop pellets. Fresh simply means that the hops, whatever dried form they are in, have been maintained and stored with care and have not deteriorated to an unusable degree. The entire art of using hops cannot get any more essential than this. Have a homebrew and think about this.
While you’re contemplating, let’s sneak in one other significant point. Bitterness and hop flavor are relative. When discussing hop bitterness and flavor we must always bear in mind that we are referring to bitterness and flavor in beer. While this may seem to be a trivial point, many a brewer has gone temporarily astray by making comparisons of hop bitterness and flavor in other aqueous solutions, such as teas, hot, cold or otherwise. Assessments of hop teas, though of limited instructional value, cannot, should not and must not be seriously correlated to predictive characters in beer. It just ain’t the same.
Before getting into a serious discussion about hop anatomy, it is worth noting that hops have been used for things other than beer. Call it the lupulin effect if you wish, but regardless of what you name it, hops do have a calming effect on the nerves, so much so that herbalists will recommend hop tea as a remedy for insomnia. More strangely, the smell of hops is said to help induce sleep. Usually hops and other herbs are combined as ingredient stuffing to make a “dream pillow.” When slept with, the pillow not only induces deeper sleep but promotes vivid dreams. Most people are skeptics about this effect, but I have found through personal experimentation that these dream pillows work very well. So, for all the lupomaniacs and hopheads, here is a recipe for making a dream pillow.2
The following mixed ingredients will stuff two 8-inch-by-6-inch pillows
2 oz. (56.8 g.) of your favorite dried whole hops
2 oz. (56.8 g.) dried chamomile flowers
2 oz. (56.8 g.) dried rosebuds, crushed
1 oz. (28.4 g.) dried mugwort
1 oz. (28.4 g.) dried lemongrass
½ oz. (14.2 g.) benzoin (this is a natural preservative)
Bag this mix in double-layered cheesecloth. Sew together an outer pillow from material that is attractive and tightly woven. Sleep with this dream pillow near your bed pillows, and be warned that your dreams may be so intense that you may decide to go back to having a beer before bedtime instead.
HOP VARIETY: IT DOES MATTER
Knowing that some hops are more bitter than others and that a long boil extracts and introduces only bitterness to beer, many homebrewers are misled to think that if bitterness is all you want from hops, then it doesn’t matter what kind of hops you use. Not true. The kind of hops you use as bittering hops does indeed influence the character of beer. One only has to sample the empty bitterness of a homebrew formulated from a kit made with hop extract. These brews lack complexity and depth of flavor.
Another example to illustrate this point is to compare two beers, 1 boiled 1 hour with 2 ounces (57 g.) of 5 percent alpha-acid-rated Goldings hops, and the other boiled 1 hour with 1 ounce (28 g.) of 10 percent alpha-rated Eroica hops. Bitterness will be theoretically equal, but the resulting beers will be notably different in character. One is often led to believe that hop flavor comes only from the very volatile oil components of hops and is completely lost if the hops are boiled for 30 minutes or longer. While it is true that nearly all flavors from hop oils are lost during short periods of boiling, distinct flavor characters from bitter hop resins will remain with the beer.
Having some degree of knowledge about hop “anatomy” will help in developing an understanding of how many different ways hops can contribute to the bitter, flavor and aromatic character of beer.
HOP ANATOMY. WARNING: THIS MAY GET UGLY
The female hop plant produces flowerlike hop “cones.” These can be seedless or seeded, depending on the variety of hop and whether the character the seeds contribute is desirable. The hop cone consists of petal-like “leaves.” At the base of the leaves are tiny yellow glands called lupulin glands. The leaves contribute some tannin during the wort boil and help facilitate the precipitation of malt proteins out of the wort. The lupulin glands contain waxes, oils and resins.
Resins. There are two kinds of resins: hard and soft. Hard resins are believed by hop scientists to contribute very little, if anything, to the character of beer. Soft resins are primarily responsible for bitterness and some flavor character.
The soft resins are categorized into three groups: alpha acids, beta acids and “other.” When alpha and beta acids oxidize they fall into the “other” group. When hops are fresh the “other” resins do not contribute significantly to the character of beer. Beta acid’s principal components are lupulone, colupulone and adlupulone, none of which is very soluble. With fresh hops, beta acids do not contribute significantly to the bitter character of beer. Some hop analysts estimate that beta acids are one tenth as bitter as alpha acids—when they are soluble. Beta acids become soluble with age and oxidation. Very old hops, besides having a host of other undesirable characters, will have little if any bitterness contribution from the principally bittering alpha acid. The bitterness old hops contribute is derived mostly from oxidized beta acids.
Life is not simple, nor is how beta acids influence the bitter character of beer. Beta acids do indeed contribute to the bitterness of beer. Research has shown that their contribution can be positively perceived by the beer drinker as a preferred milder-type bitterness. This effect is more pronounced with the use of aroma-type hops because the ratio of the beta fraction to alpha acids is higher in aroma hops. For example, if two beers had identical amounts of bittering units, but one beer’s bitterness units were contributed to by a higher amount of beta acids, the bitterness character of that beer may be preferred over the beer whose bitterness contribution came more from alpha acids. Even though their bitterness units were equal.
Alpha acids’ principal components are humulone, cohumulone and adhumulone. These are the hummers that most significantly contribute bitter character to beer. They are insoluble except when treated to the vigor of a boiling wort. Then they become partially soluble and some of the alpha acids go through a chemical change called isomerization. Milligram for milligram, isomerized alpha acids (iso-alpha acids) are more bitter than alpha acids. But nonisomerized alpha acids do not dissolve or, shall we say, “melt” into the flavor of the beer. So we can only count bitterness contributed by isomerized alpha acids. (If you’re not on your second glass of beer by now, you might want to consider making a move to the refrigerator right now. I warned you it may get ugly.)
Let’s get back to the three components of alpha acid. The proportions of humulone, cohumulone and adhumulone vary among hop varieties and with the yearly harvest. Hop scientists continue to investigate their proportional relationships and what they contribute to the flavor of beer. One discovery that is generally observed is that hop varieties with a greater proportion of cohumulone tend to manifest harsher or more robust bitterness in beer. Brewers Gold, Bullion, Cluster, Nugget, Northern Brewer and Eroica are a few hops that are considered to have relatively higher levels of cohumulone. Tettnanger, Hallertauer, Fuggles, Hersbrucker and Saaz are hop varieties with lower levels of cohumulone. Because of the lower levels of cohumulone, an equivalent amount of bitterness from these hops would be expressed a bit more softly. Neither type has a general advantage over the other. The choice of hops is dependent on the style you wish to brew and, more important, your preference. Any brewer who has used the hops listed can appreciate the fact that the character of bitterness is different as cohumulone varies.
Hop oils. Hop oils are the principal contributors to hop flavor and aroma in beer. Many of the more volatile components evaporate completely within about 20 minutes’ boiling time. Some components remain behind despite boiling. There are many different types of oils that are present in varying proportion, depending on the variety of hop and the particular harvest. Two significant oils worth mentioning in this discussion are humulene and myrcene. Hop scientists tell us hops with a higher proportion of myrcene contribute a harsher and more unpleasant aroma and flavor. Bullion and Cluster are good examples. These types of hops generally are avoided as flavor or aroma hops. Hops with relatively higher levels of humulene are preferred as aroma and flavor hops because of their subjectively pleasant character. Hops such as Hallertauer, Tettnanger and Saaz fall into this classification. Very interestingly, a certain amount of slow, low-temperature oxidation of humulene oils enhances the desirability of these types of hops as flavor and aroma hops. This oxidation could be considered a type of maturation or aging process.
HOP OILS: COMPARISON OF TYPICAL COHUMULONE, MYRCENE, HUMULENE PROPORTIONS IN AROMA AND BITTER VARIETIES OF HOPS
Higher-Alpha-Acid Bittering Varieties
Hops Type: Northern Brewer (German)
(Resin) Cohumulone: 30%
(Oils) Myrcene: 36%
(Oils) Humulene: 31%
Hops Type: Brewers Gold (German)
(Resin) Cohumulone: 45%
(Oils) Myrcene: 39%
(Oils) Humulene: 30%
Hops Type: Nugget (German)
(Resin) Cohumulone: 28%
(Oils) Myrcene: 29%
(Oils) Humulene: 38%
Hops Type: Chinook (American)
(Resin) Cohumulone: 32%
(Oils) Myrcene: 37%
(Oils) Humulene: 23%
Hops Type: Cluster (American)
(Resin) Cohumulone: 39%
(Oils) Myrcene: 50%
(Oils) Humulene: 17%
Hops Type: Galena (American)
(Resin) Cohumulone: 37%
(Oils) Myrcene: 57%
(Oils) Humulene: 17%
Lower-Alpha-Acid Aroma/Flavor Varieties
Hops Type: Hallertauer Tradition (German)
(Resin) Cohumulone: 26–28%
(Oils) Myrcene: 21%
(Oils) Humulene: 40–48%
Hops Type: Hallertauer (American)
(Resin) Cohumulone: 21%
(Oils) Myrcene: 39%
(Oils) Humulene: 34%
Hops Type: Mt. Hood (American)
(Resin) Cohumulone: 23%
(Oils) Myrcene: 60%
(Oils) Humulene: 20%
Hops Type: Hersbrucker Pure (German)
(Resin) Cohumulone: 26%
(Oils) Myrcene: 23%
(Oils) Humulene: 27%
Hops Type: Tettnanger (German)
(Resin) Cohumulone: 27%
(Oils) Myrcene: 20%
(Oils) Humulene: 25%
Hops Type: Tettnanger (American)
(Resin) Cohumulone: 23%
(Oils) Myrcene: 40%
(Oils) Humulene: 21%
One cannot have an American discussion of hop oils without at least mentioning what makes Cascade hops a unique hop. Geraniol and linalool (they sound like two characters from The Hobbit, don’t they?) are primarily responsible for the citrusy and floral character found in Cascade hops. The Cascade hop is a poor storing hop and ages quickly. These compounds occur at high levels soon after harvest.
LOVE AND HATE TO THE BITTER END
All those good resins, and it’s all a brewer can do to get hold of 30 percent of them. It’s a struggle every step of the beermaking way. The bitter hop resins are not only stubbornly soluble, they have a tendency to go by the wayside during the beermaking process. For simplicity many brewers take into account a kettle/wort boil utilization factor, but there are many other factors, though of lesser significance, that determine how much of the bitter stuff finally gets into beer. Though this subject is often discussed in basic books on brewing, it is worthwhile to review and list some of the more significant considerations that determine the development and utilization of hop bitterness.
In the kettle
- Hop utilization decreases with an increase of wort gravity (see Hop Utilization Chart in Beer Recipes). This is somewhat analogous to dissolving sugar in water; as the solution approaches saturation, it takes longer for the sugar to dissolve. Recall that alpha acids must be dissolved before they can become isomerized and affect beer bitterness.
- Hop utilization decreases with an increase of hop rate; the more hops added to the wort, the lower the utilization. Some brewers will choose to add bittering hops in stages to maximize their bitterness yield. (This also is a way of controlling or influencing oil component loss.)
- The same amount of hop pellets will be more utilized than whole hops. As an example, whole hops might be 28 percent utilized while, given the same conditions, hop pellets might be 33 percent utilized. While the difference in utilization is 5 percent, what this really indicates is that one must use 18 percent more whole hops than pellets if the recipe was designed for hop pellets, and one must use 15 percent less hop pellets if a recipe was designed for whole hops.
- Hop utilization increases with longer boilings up to about 1½ hours for normal worts and up to 2½ hours for very high gravity worts.
- Hop utilization levels off with excessive boils. The iso-alpha acids you’ve worked so hard to create begin to break down. The loss is about equal to the gain.
Stages elsewhere in the process that affect the overall hop utilization factor
- Some hop bitterness can be lost during the fine filtration of finished beer.
- The loss of hop bitterness increases as fermentation temperatures increase. You will lose a higher percentage of hop bitterness with more bitter beers.
- Some hop bitterness can be lost to trub, hot and cold break material.
- Some hop bitterness can be lost to fermentation kraeusen foam expelled from the fermenter or adhering to the walls of the fermenter.
- Some hop bitterness can be lost to yeast sediment.
- Professional brewers have indicated that when increasing batch sizes dramatically, let’s say from 5-gallon test batches to 10-barrel production batches, hop utilization usually increases. Proportionally less hops are needed for the same amount of bitterness. At first this may seem as though the kettle configuration affects utilization, but by reviewing many of the preceding points, a crafty brewer should realize that there are many other factors that have changed along the wort’s way to beer.
If all of this weren’t enough to consider, think about this next factoid before taking another sip of your favorite brew. Water hardness and certain minerals can affect the perception of bitterness. Increased hardness will create a relatively harsher sensation of bitterness. Within reason, this is neither good nor bad. The unique bitter character of world-class beers such as Bass Ale can be attributed partly to the hardness of the brewing water. It is worth noting that classic Czechoslovakian Pilseners are brewed with extremely soft water with very few minerals present. Their bittering rates and formulations would lead one to anticipate an extremely bitter beer, but the softness of the water helps create palatability, allowing these Pilsener beers to be highly hopped. Highly hopped, their flavor and aroma are enhanced by the combination of soft water and high hopping rate, though the perception of bitterness is kept palatable.
IBU, BU, AAU, HBU. WHAT’S GOING ON HERE?
There are several ways to express bitterness and bitterness potential. International Bitterness Units (IBUs) refer to the same scale as Bitterness Units (BUs). One BU is equal to 1 milligram of isomerized alpha acid in 1 liter of wort or beer. This is a system of measuring bitterness devised by brewing scientists and is an accepted standard throughout the world.
Homebrew Bitterness Units (HBUs) are the same as Alpha Acid Units (AAUs), the system first devised by the late British homebrew author and pioneer Dave Line. One HBU is equal to a 1 percent alpha acid rating of 1 ounce (28.4 g.) of hops. HBUs are calculated by multiplying the percent of alpha acid in the hop by the number of ounces of hops. Ten HBUs could be equal to 2 ounces (57 g.) of a 5 percent alpha-acid-rated hop or 1 ounce (28.4 g.) of a 10 percent alpha-acid-rated hop. Contrary to what BUs represent, HBUs or AAUs are not a measure of bitterness in beer. They are simply an indication of the amount of alpha acid called for in a recipe, which is a first step in figuring how much bitterness could end up in your beer.
Infrequently you may come across a professional recipe that specifies the amounts of bittering hops in terms of milligrams alpha acids/liter. This is not an indication of how bitter the beer is or of its BUs. It is used to devise a recipe for any given volume of beer. If the bittering hop amount is given in terms of mg./l. alpha acid, first you must determine how many liters you are going to brew and multiply that amount times mg./l. to determine how many total milligrams of alpha acid will be needed for the recipe. Alpha acid rating of hops is expressed as a percentage of the total weight of the hop. For example, if you have 1 ounce (28.4 g.) of 5 percent alpha acid hop, then you have .05 ounce of alpha acid. Multiply .05 times 28.35 to convert to 1.418 grams or 1,418 milligrams. Working the other way, you can determine that if you need 200 mg./l. alpha acids and you wish to make a 19-liter (5-gal.) batch, then:
19 liters × 200 mg./l. = 3,800 mg. of alpha acids = 3.8 grams
If a 5 percent alpha acid hop were used, then:
= 76 grams (2.68 oz.) of hops
Lupomaniacs and Freshly Picked Hops
Those who grow their own hops can’t help but wonder if there is a secret advantage to using freshly picked hops (i.e., fresh off the vine and sun-dried) in brewing. Unfortunately encouragement can’t be offered. There are a lot of undersirable chlorophyll-like grassy flavors that evaporate along with moisture when hops are dried. It’s likely that those “fresh green” flavors would not enhance the character of your beer. But if you wish to experiment, here are some guidelines. Freshly picked hops are about 80 percent moisture. When dried they are reduced to about 8 percent moisture. Given this ratio, you would use by weight about ten times more undried hops than dried hops called for in a recipe.
Here’s a hopbit: Interesting results were found by German hop researchers when they tested the stability of frozen undried hops. They found that the undried hops, when frozen, were significantly more stable than dried hops stored under identical conditions. Practically speaking, freezing ten times more water and dealing with increased volumes does not make this procedure commercially viable. But then, there are homebrewers….
Having already noted that volatile hop oils are the principal contributors to beer’s hop flavor and aroma, logically their infusion should come during the final 20 minutes or 2 to 5 minutes, respectively, of the wort boil. If the boil is stopped and the wort cooled as quickly as possible, volatile oils contributing to late hop flavor and aroma will be preserved through to the final product.
Dry hopping is another means to infuse hop flavor and aroma into beer. British brewers use this method to give a special hop character to selected ales. The process involves adding selected aromatic varieties of hops to beer in cold storage, during the stage of final maturation. In Great Britain hops were traditionally added directly into the serving cask, where the hop oils were allowed to meld with the overall beer character.
General Guide for Imparting Maximum and Minimum Potential Hop Aroma, Flavor and Bitternes
Homebrewers can consider this traditional method of infusion, but must plan to deal with the potential of loose hops in the tapping system. A more practical approach for most homebrewers would be to add aroma hops at a general rate of ¼ to 1 ounce (7 to 28 g.) to secondary fermentation during the final one or two weeks before bottling or kegging. Separate the spent hops by carefully siphoning.
This procedure often brings to question the risk of contaminating the beer with undesirable microorganisms. There are several reasons why this risk is not as great as it may appear. Dry hopping should be done in the secondary or lagering vessel and absolutely avoided during primary fermentation. By the time beer is in the secondary, the alcohol, lower pH (higher acidity) and lack of oxygen in the beer serve to inhibit bacteria that might be introduced at this point. Beer spoilage organisms are not as likely to choose hops as a resting place, because hops themselves have an antiseptic property.
Cleanly packaged hops should be sought. Hop pellets can be used with great effect. Their use will minimize risk of serious contamination, though experienced brewers will argue both the pros and cons of the character they contribute compared to whole hops.
Lupomaniac immersed in a mountain of hops becomes momentarily dazed before becoming a brewer for life.
If you are at the brink of worrying, don’t. There may be other alternatives worth considering that perhaps will result in more controllable results. Make a concentrated hop tea and add it to the finished beer. You might even consider making a cold tea by soaking hops in a jar of water, sealed and refrigerated for a week. Add these teas in amounts that suit your taste at bottling time. When making any tea that will be added to the finished beer, be sure to use deaerated water. This can be accomplished by boiling.
A final 2-minute steep of aroma hops in the wort boil, or the addition during secondary: Which is better? Some brewers claim that dry hopping results in more stability of the sought-after character. You’re a homebrewer. Try both methods.
Now that we’ve come this far, you have two choices. You could become obsessed and try to do something about everything that affects hop utilization or you could get practical and have a homebrew.
Yes, you now have a feeling and an understanding of what the art of using hops is all about. You don’t just have to believe what someone else tells you, but rather you can consider it from your knowledgeable perspective and decide what to do. If and when you change brewing equipment or procedures, you’ll have an idea of what to expect. Or maybe you’ll be surprised, but then you’ll be able to recover easily.
Practically speaking and from one homebrewer to another, don’t get bogged down in obsessive details. After all, the very truth of the matter is that no matter how fresh your hops are, they are going to vary as much as 20 percent (i.e., plus or minus 10 percent) from the alpha acid rating you’ve been told they are. (Note: That’s plus or minus 10 percent difference, not plus or minus 10 percent alpha acid weight.) Why? Because a hop plant grown on one side of the ditch may have received more water than a hop plant grown on the other. Perhaps the sample bale that the hop company based their analysis on was the one in the middle of the room and not the one you got your hops from (which was stored up against the wall). Maybe your hop cones were harvested on a Tuesday and the analyzed sample was harvested on Friday. Perhaps the shipment to your shop took eight days rather than three days.
To put things in a clearer and more practical perspective, consider for example that a 0.5 percent difference in an alleged 5 percent alpha-acid-rated hop is 10 percent. Now what? Establish your own procedures and determine your own overall utilization factor. Be consistent, and the law of averages and the errors of misplaced precision will be in your favor.
Be careful when converting all-grain recipes to extract recipes that use a concentrated wort boil. Remember, hop utilization decreases with concentrated wort boils. While a 60- to 90-minute boil of an all-grain recipe may get 30 percent utilization, the same boiling time of 6 pounds (2. 7 kg.) of extract boiled in 2 gallons (7.6 l.) of water will result in a 23 percent utilization. Do a little math and you will realize the necessity of adding 25 percent more hops to have the same contribution to bitterness.
Likewise, if extract brewers wish to convert their boiling procedures to full wort boils (see Beer Recipes), the reverse of this principle applies; you need to consider reducing bittering hops by 25 percent.
Converting from a concentrated wort boil to a full wort boil (or vice versa) and substituting hop pellets for whole hops (or vice versa) can lead to as much as a 30 to 40 percent difference in the amount of bittering hops called for in a recipe in order to match what the recipe formulator intended. That’s quite startling if you’ve never considered it before.
There’s not much to say here, but what there is to say is absolutely essential. Keep the hops cold, at or around freezing. Keep them double-plastic-bagged or in an airtight container or jar. Many brewers do not appreciate the importance of sealed containers and minimizing contact with air. Compressed hops, sealed in a jar with minimal air and stored in the freezer, will keep for years. Slow oxidation of some aroma-type hops will even enhance their character.
Interestingly, the more prized the hop, the poorer stability it has at room temperature. This is particularly true with the aroma-type (sometimes referred to as Noble) hops such as Hallertauer, Tettnanger, Saaz, and their hybrids such as Mt. Hood.
Time for a beer? You betcha!
zymurgy magazine 1990, volume 13, number 4, special “Hops and Beer” issue. Articles include “History of Hops,” “Development of Hop Varieties,” “Hop Varieties and Qualities,” “Assessing Hop Quality,” “Processing Hops into Bales and Pellets,” “Hop Products,” “Hop Oil: Aroma and Flavor,” “Growing Hops at Home,” “Propagating Hops,” “Factors Influencing Hop Utilization,” “Calculating Hop Bitterness,” “Matching Hops with Beer Styles.”
Hops, by R. A. Neve, Chapman and Hall, 1991. Comprehensive book on hop cultivation.
Homegrown Hops, by David Beach, David R. Beach, 1988. Practical advice and procedures for home cultivation.
Using Hops, by Mark Garetz, Hop Tech Books, 1994. Practical and thorough discussion for the small-scale brewer.