Calculos de IBU

8/11/2019 Calculos de IBU

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essential in bringing this information together. Again, if you've contributed to this FAQ, don't see your name listed, and

would like it listed, please contact me. No slight was intended, but with so much information from so many sources, it is

easy to lose a name. Also, if your email address has changed, it would be nice to update that.

Cheers,

Norm

What Are Hops?

Hops are cultivated flowers (humulus lupulus), green in color with yellow lupulin glands down between the petals, used

for preservative and flavoring characteristics in beer. The bitterness of the hop is used to balance the sweetness of the

malt, and the essential oils add a flavor/aroma which cannot be achieved by using any other plant. The hop plant is a

perennial spiraling vine which will grow in almost any climate given enough water and sunlight. It can climb either

string or poles and can reach heights of 40 feet. The flowers (or cones as they are often called) are usually dried before

use.

Bittering Compounds

One of the major contributions hops give to beer is a characteristic bitterness that provides a counterpoint to the rich

sweetness provided by the malt. This bitter flavor is extracted from the hops during the boil. It is during this time thatvirtually insoluble alpha acids are isomerized (rearranged without changing their composition) into more soluble and

stable iso-alpha acids, the main bittering substance in beer. Five different naturally occurring alpha acids have been

isolated from hops which are:

humulone

cohumulone

adhumulone

prehumulone

posthumulone

Although isomerized alpha acids are the biggest contributers, hops contain beta acids which also add bitterness to beer.The beta acids are similar to alpha acids both in structure and abundance. In contrast to alpha acids, it is not isomerized

beta acids that add bitterness, it is the oxidation products of the beta acids, which are bitter and soluble, that make their

presence felt. It should be noted that oxidized beta acids are not as bitter as isomerized alpha acids, and thus contribute

much less to the final bitterness of the beer.

Both the alpha and beta acids are very susceptible to oxidation, especially at temperatures above freezing. Theoretical

losses of alpha acids of up to 60% have been calculated for hops which are packaged and stored poorly. This is

important because once alpha acids have been oxidized they can no longer be isomerized into iso-alpha acid, thus

decreasing the hop's bittering potential. As stated above, oxidation components of beta acids contribute to bitterness, thus

the bittering potential of oxidized hops may not decrease as much as is commonly thought. This does not, in any way,

argue against storing hops well, since essential oils are dramatically and negatively altered by oxidation.

For these reasons, the "storageability" of each hop variety is sometimes provided, along with the alpha and beta acid

levels, by the hop broker. This parameter is usually given as a percentage of the alpha acids present after 6 months at

20C. Some good storage hops (usually high alpha acid) lose only 15-20% of their alpha acids: Cluster and Galena are

among the best. Most high quality aroma hops lose anywhere from 35-65% of their alpha acids unless anaerobic

conditions and cold storage (< 0C) are provided. This is why it is imperative for brewers to buy the freshest hops

available and store them in the coldest environment available, usually the freezer. It is also important to package the hops

properly, which means removing as much oxygen as possible and containing them in an oxygen barrier material.

Aroma and Flavor Compounds

Hops bring a lot more to beer than bitterness. The volatile oils, usually 0.5 - 3.0% (vol/wt) of the hop cone, are an

important flavor component of many types of beer. Brewers seeking to maximize hop flavor and aroma generally make

late kettle additions (0-15 min. before cooling) with high quality "aroma" hops. Dry hopping, i.e. the addition of hops to

the secondary fermenter or serving tank, is another way to add hop character to a beer although the aroma components


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Loose Hops

Advantages: They are the most natural form of the ingredient. They float, which is good for siphoning out from under,

and form a natural filter bed. When they are fresh, they beat all other forms in delivering the original hop compounds to

the beer (processing hops alters the volatile hop compounds in many ways).

Disadvantages: They float, so some contact with a still wort (as in dry hopping) is thought to be lost this disadvantage is

certainly arguable though, especially when it is considered that by using weighted hop bags, it is a non-issue. Since they

are loose, exposure to air (oxygen) may be greater which could cause them to lose quality more quickly than the other

forms of hops (note that this point is debatable). When stored in vacuum- sealed or CO2 or nitrogen purged Oxygen

barrier bags or jars, this potential problem can be avoided. They are bulkier than other forms.

Plugs

Advantages: Are nearly the same as loose hops, in that, when hydrated, they become whole hop cones again. Like loose

hops, they float. They may be better protected from air, but this is unproven.

Disadvantages: Few hop varieties come in this form. Currently, any domestic varieties are first shipped to England

where they are made into plugs and then shipped back to the U.S. This probably negates any potential freshness

advantage they have over loose hops (for U.S. varieties). It is difficult, but not impossible to separate into increments

smaller than 0.5 oz. The compression of the hops into this form causes the lupulin glands to burst, which causes a finiteloss of the volatile hop aromatic compounds and could cause increased alpha acid oxidation.

Pellets

Advantages: Convenient to measure and may have better protection from air (another unproven assumption). They sink,

so they get maximum contact in a still wort, as when used for dry hopping (may or may not be an advantage). If they are

subsequently covered with dead yeast, wort contact is mostly lost, so careful timing is recommended when using them

for dry hopping. They reportedly contribute 10% more alpha acids to the wort because of maximized surface area, so are

a more efficient use of this relatively expensive ingredient. They are generally available in more varieties.

Disadvantages: They sink and are powdered, so it is difficult to avoid them when siphoning. The extra processing ofchopping and compressing negatively affects hop compounds.

Given the pros and cons listed, the choice of which form of hop to use in a certain application is up to the individual

brewer and dependent upon the individual brewhouse. With some kettle arrangements (those using a hopback, for

instance) loose hops can form a utilitarian filter bed. In others, the mass of loose hops can be a nuisance and soak up a

large quantity of wort which is lost to the brewer. It should be noted that fresh, whole hops are available today from

many sources, including mail-order nationwide (US) from companies such as Just Hops, Freshops, and HopTech, which

may negate many of the advantages of processed hops.

Estimating Beer Bitterness

The simplest way to describe the bittering potential of a given hop sample is to use Alpha Acid Units (AAU) or

Homebrew Bittering Units (HBU) (they're the same). For the sake of discussion we will use the term AAU, which is

calculated as follows:

AAU = AA * W

where:

AA = alpha acid % provided with the hops

W = weight of the hops in ounces

AAU's are literally hundredths of an ounce, so the units would be ounces. This is a bit awkward, and they are usuallydiscussed as if they are "unit-less". It is generally assumed that, when using AAU or HBU, the batch size is the standard

homebrewing unit of 5 gallons. If a beer is said to have 10 AAU's of bitterness in it, and it is a 5 gallon batch, there

would probably be no confusion. On the other hand, if it is a 10 gallon batch, there is actually half the AAU's per gallon


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when compared to the 5 gallon batch and the beer would be quite different. Another drawback to using AAU's is that

they don't consider the utilization obtained from long, intermediate, or short boil times. Fudge factors are sometimes

added but at best they offer a rough approximation.

To help solve these problems, the International Bittering Unit (IBU) may be used. An IBU is defined as 1 mg/l of iso-

alpha-acid in a solution. By estimating IBUs rather than HBUs, the brewer can get a more accurate (though admittedly

still rough) approximation of the bitterness imparted into the beer by the hops. It is independent of batch size so that a 5

gallon batch with 29 IBU's has the same bitterness as a 50 barrel batch with 29 IBU's. The equations are commonly

quoted from Jackie Rager's article in the "Zymurgy" Hops and Beer Special Edition published in 1990. Revised

numbers and formulae have recently been presented by Glenn Tinseth and Mark Garetz, in separate works. Rager hasbeen taken to task for not supplying enough background references, and not fully explaining how he got his numbers. In

general, his utilization estimates are believed to be optimistic. Garetz has been accused of extrapolating scant laboratory

information, and overgeneralizing because of it. His numbers have been labelled unrealistic on the pessimistic side.

Tinseth has just presented a revised method and set of tables, and though they are thought to be quite accurate, they have

not stood the test of time. The calculated numbers tend to fall in between Rager's and Garetz's. Note also that these are

all estimates. Actual IBUs can be measured in a laboratory, but the average homebrewer has no access to such

equipment. The Rager, Garetz, and Tinseth estimation methods follow.

Rager Method

Boiling Time (minutes) %Utilization-----------------------------------0 - 5 5.06 - 10 6.011 - 15 8.016 - 20 10.121 - 25 12.126 - 30 15.331 - 35 18.836 - 40 22.841 - 45 26.9

This utilization can be reduced to a smooth function, as opposed to the table, which produces many discontinuous lines.

The Rager table is represented by the following utilization equation:

%UTILIZATION = 18.11 + 13.86 * hyptan[(MINUTES - 31.32) / 18.27]

According to Rager, if the gravity of the boil exceeds 1.050, there is a gravity adjustment (GA) to factor in:

GA = (BOIL_GRAVITY - 1.050) ---------------------- 0.2

otherwise,

GA = 0

Metric Units

IBU = (GRAMS OF HOPS) * %UTILIZATION * %ALPHA * 1000 ------------------------------------------------ VOLUME(litres) * (1 + GA)

Non-metric Units

IBU = (OUNCES OF HOPS) * %UTILIZATION * %ALPHA * 7462 ------------------------------------------------- VOLUME(gallons) * (1 + GA)

Jackie Rager's numbers have been used successfully by thousands of homebrewers and provide a consistent base with

which to work. Note that the figures expressed as percent should be entered as decimal values in the formula (9% =

0.09). It is apparent that his constant 7462, derived from metric to US conversion, is actually closer to 7490. The GA

factor could be questioned as well, as it is intuitively obvious that a gravity of 1.049 does not affect utilization exactly the

same as a gravity of 1.000 (water). It is assumed (but not verified) that the utilization table is corrected for this


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assumption and/or the difference is small enough that it has little effect on the final bitterness of the beer.

The unfortunate part of Rager's article is that it is completely lacking in references, so assumptions come with it part and

parcel. Note also that Rager's numbers are often used for pellet hops thrown loose in the boil. Al Korzonas suggests

adding 10% more hops if used in a hop bag, and 10% more than that if loose hops or plugs are used.

Garetz Method

It has been reported that since iso-alpha acids possess a slight electrical charge, they can be lost in many ways. Among

these are absorption into the yeast cell walls (and subsequent removal of the yeast), attachment to coagulating proteins

(and subsequent removal of this trub), attachment to filters, etc. It is unclear if Mr. Rager's utilization numbers have

assumed these losses, but it can be assumed that Tinseth and Garetz did take them into account. The Garetz numbers

below represent average yeast flocculation he also provides tables which represent fast and slow yeast flocculation.

Boiling Time (minutes) %Util (Avg Yeast)----------------------------------------0 - 5 06 - 10 011 - 15 216 - 20 521 - 25 826 - 30 1131 - 35 1436 - 40 1641 - 45 1846 - 50 1951 - 60 2061 - 70 2171 - 80 2281 - 90 23

According to Garetz, there are several adjustment factors, that he brings together in the formula with the term "combined

adjustments" (CA):

CA = GF * HF * TF

where GF is the Gravity Factor, HF is the Hopping Rate Factor, and TF is the Temperature Factor. To calculate it all, he

starts with some he calls CF:

Concentration Factor: CF = Final Volume / Boil Volume,

to account for concentrated boils of extract brews.

Next, calculate Boil Gravity (BG):

BG = (CF * (Starting Gravity - 1)) + 1

Then calculate GF:

BG - 1.050GF = ---------- + 1 .2

HF is calculated as follows:

HF = ((CF * Desired IBUs)/260) + 1

TF is based on elevation as follows:

TF = ((Elevation in feet) / 550) * 0.02) + 1

These are all put into the following formula, along with the utilization from the table, and the IBUs are calculated. Notetwo things: 1) the utilization and alpha acids should be expressed as whole numbers (7% = 7), and 2) this process is

iterative, since it contains a term (HF) based on your goal IBUs. You must guess at the final result, do the math, and

rerun the process, each time adjusting the value downward. It takes a little practice, but can be done.


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Metric Units

IBU = (%Utilization) * (%Alpha) * Hop weight(grams) * 0.1 --------------------------------------------------- Volume(liters) * CA

Non-Metric Units

IBU = (%Utilization) * (%Alpha) * Hop weight(ounces) * 0.749

------------------------------------------------------ Volume(Gallons) * CA

Garetz goes to allow for a yeast factor (YF), pellet factor (PF), bag factor (BF), and filter factor (FF), and comes up with:

CA = GF * HF * TF * PF * BF * FF

This allows you to adjust the formula based on your own brewery and practices.

Tinseth Method

Glenn Tinseth's method doesn't involve as many factors, but is still a bit more complex than the original Rager

method.Tinseth notes that his table is optimized for fresh whole cones loose in the boil, although easily adjustable for

other forms of hops. He builds the gravity adjustment into the utilization tables and offers the following:

Decimal Alpha Acid Utilization vs. Boil Time and Wort Original Gravity

Boil Original GravityTime 1.030 1.040 1.050 1.060 1.070 1.080 1.090 1.100 1.110 1.120 1.130(min) 0 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3 0.034 0.031 0.029 0.026 0.024 0.022 0.020 0.018 0.017 0.015 0.014 6 0.065 0.059 0.054 0.049 0.045 0.041 0.038 0.035 0.032 0.029 0.026 9 0.092 0.084 0.077 0.070 0.064 0.059 0.054 0.049 0.045 0.041 0.03712 0.116 0.106 0.097 0.088 0.081 0.074 0.068 0.062 0.056 0.052 0.04715 0.137 0.125 0.114 0.105 0.096 0.087 0.080 0.073 0.067 0.061 0.05618 0.156 0.142 0.130 0.119 0.109 0.099 0.091 0.083 0.076 0.069 0.06321 0.173 0.158 0.144 0.132 0.120 0.110 0.101 0.092 0.084 0.077 0.07024 0.187 0.171 0.157 0.143 0.131 0.120 0.109 0.100 0.091 0.083 0.07627 0.201 0.183 0.168 0.153 0.140 0.128 0.117 0.107 0.098 0.089 0.08230 0.212 0.194 0.177 0.162 0.148 0.135 0.124 0.113 0.103 0.094 0.08633 0.223 0.203 0.186 0.170 0.155 0.142 0.130 0.119 0.108 0.099 0.09136 0.232 0.212 0.194 0.177 0.162 0.148 0.135 0.124 0.113 0.103 0.09439 0.240 0.219 0.200 0.183 0.167 0.153 0.140 0.128 0.117 0.107 0.09842 0.247 0.226 0.206 0.189 0.172 0.158 0.144 0.132 0.120 0.110 0.10145 0.253 0.232 0.212 0.194 0.177 0.162 0.148 0.135 0.123 0.113 0.10348 0.259 0.237 0.216 0.198 0.181 0.165 0.151 0.138 0.126 0.115 0.10551 0.264 0.241 0.221 0.202 0.184 0.169 0.154 0.141 0.129 0.118 0.10854 0.269 0.246 0.224 0.205 0.188 0.171 0.157 0.143 0.131 0.120 0.10957 0.273 0.249 0.228 0.208 0.190 0.174 0.159 0.145 0.133 0.121 0.11160 0.276 0.252 0.231 0.211 0.193 0.176 0.161 0.147 0.135 0.123 0.112

70 0.285 0.261 0.238 0.218 0.199 0.182 0.166 0.152 0.139 0.127 0.11680 0.291 0.266 0.243 0.222 0.203 0.186 0.170 0.155 0.142 0.130 0.11990 0.295 0.270 0.247 0.226 0.206 0.188 0.172 0.157 0.144 0.132 0.120120 0.301 0.275 0.252 0.230 0.210 0.192 0.176 0.161 0.147 0.134 0.123

To calculate IBUs, the formula is simple:

IBUs = decimal alpha acid utilization * mg/l of added alpha acids

For those who want to make adjustments based on their own brewery, he offers the following:

Metric Units

mg/l of added alpha acids = decimal AA rating * grams hops * 1000 ------------------------------------- liters of wort

Non-Metric Units


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mg/l of added alpha acids = decimal AA rating * ozs hops * 7490 ------------------------------------- gallons of wort

The decimal alpha acid utilization is calculated using Tinseth's two empirical factors: the Bigness factor and the Boil

Time factor.

Decimal Alpha Acid Utilization = Bigness Factor * Boil Time Factor

The Bigness Factor accounts for reduced utilization due to higher wort gravities.

Bigness factor = 1.65 * 0.000125^(wort gravity - 1)

The Boil Time Factor gives the varying utilization based on boil time:

Boil Time factor = 1 - e^(-0.04 * time in mins) -------------------------- 4.15

Some comments from Tinseth:

"The numbers 1.65 and 0.000125 are empirically derived to fit my data. The number 0.04 controls the shape of the util

vs. time curve. The factor 4.15 controls the max util value--make it smaller if your util is higher than mine.

I'd suggest fiddling with 4.15 if necessary to match your system, only play with the other three if you like to muck

around. I make no guarantees if you do.

You might notice that the shape of the util curves is very similar to that of Randy Mosher's. He and I seem to have

independently arrived at the same conclusion.

The really cool thing about these new equations is that they are easily customizable. I believe the basic form is correct--

by playing with the different factors, different brewers should be able to make them fit their breweries perfectly. The root

of the equations is the basic first order chemical reaction, i.e. the AA isomerization seems be first order (or pseudo-first

order)."

Bitterness Summary

It should be obvious that the alpha acid utilization is a widely debated topic, and that it is not an exact science.

Homebrewing systems vary so widely that it is impossible to be very accurate with the IBU estimates. The homebrewer

who strives to be accurate within 10% of actual can probably achieve it, and verify it with known commercial examples.

The human tongue is accurate enough for this delightful experiment. Precision with IBUs is certainly achievable, with

careful record-keeping, including personal sensory descriptions, and the use of a consistent set of formulae and

utilization tables. These steps will go a long way toward consistent quality beer.

One question that appears on occasion is whether you lose bitterness if you boil the hops for too long, e.g. longer than

two hours. According to Glenn Tinseth, multiple studies have shown that alpha acid utilization always increases withboil time, even out to 3 hours of boiling. The reason the tables quit around 60 minutes of boiling, is that little utilization is

gained beyond that. In fact, after about 45 minutes the curve becomes quite flat. In other words, beyond that the

utilization increase is small compared to the added time involved. It is speculated that commercial brewers found that

beyond 45-60 minutes or so, the benefit of the added utilization was more than offset by the cost of the energy to

continue the boil as well as the cost of the added time in the process.

A final note about bitterness: IBUs are not the final word when it comes to the perceived bitterness of beer. Sulfates,

dark grains, tannins, and other compounds found in beer contribute to the bitterness sensation. For this reason,

comparison of bitterness between styles (and sometimes even different beers within a style) is difficult.

How Bitter Should It Be?The AHA and probably other organizations publish (large) charts which define the range of IBUs expected in a given

style. It is outside the scope of this FAQ to go into that much detail on beer styles, but hopping rates from 10 IBU to 60


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Hop blossoms start out looking like large sand burrs, and then take on a characteristic cone shape as they grow in size.

The size of a fully developed cone depends on the variety, varying from 1 to 2 inches long by 1/2 to 1 inch in diameter.

The hops are fully mature and ready for picking when two changes take place. First, immature hops have a damp, soft

feel and when squeezed slightly tend to stay compressed. Mature hops feel more like paper, spring back when squeezed,

and feel noticeably lighter. The second key test is to pick an average example hop and cut it lengthwise down the center

with a knife. When ready to pick, the yellow powder (the lupulin sacs containing the essential oils and bitter compounds)

will be a dark shade of yellow, like the stripes on a highway, and it will be pungent. If a light shade of yellow then its

likely the hops are immature.

When ready to pick it is best to snip the stems of the cones with scissors or a knife to avoid jarring the hops and

knocking lupulin powder out or worse, pulling the center of the cone out with the stem, causing a great loss of lupulin.

Touching hops plants can cause skin irritation in some people gloves and long sleeves can help in this matter.

Just-picked hops are roughly 80 percent water if left alone they spoil rapidly. For proper storage most of the water is

removed by drying. A good drying method is to lie the hops on a card or screen in an attic. Just a few hours during the

heat of summer or a few hours more in cooler weather is enough to dry the hops. Use a before and after weighing (and

trial and error) to try to achieve about 7-10 percent residual moisture after drying.

After drying, hops keep best at low temperatures and away from oxygen. A kitchen freezer easily takes care of

temperature but to get the hops away from oxygen is difficult. Tightly packing hops in canning jars will minimize the

trapped air but be careful not to use too much force and break the all important lupulin sacs since this accelerates

oxidation. Purging the canning jar of oxygen by blowing in carbon dioxide from a kegging system will also help prolong

freshness.

It's common to get 4 or 5 harvests per year by picking the biggest, most mature hops every 2 weeks or so as the flowers

ripen. Patience and judgement are important since cones left on the vine too long turn brown and begin to oxidize and

spoil, while immature hops have little lupulin to give.

At the end of the growing season when the leaves have fallen or turned brown, cut the vines at the surface of the soil and

if possible remove the twine. After cutting back the vines a layer of 3 or 4 inches of mulch and composted manure can

be put over the exposed vines for insulation and nutrition during the winter.

Japanese beetles are the number one nuisance in many areas. A common remedy is to position a "Bag a Bug" type

beetle trap about 30 feet directly up wind from the hop vines. There is some concern that the "Bag a Bug" traps may

actually attract more beetles than they catch, but that probably depends on the situation. Certain plants such as rose

bushes may also attract the beetles, so it's best to keep those plants away from your hops. Also, the beetles' larvae live in

the ground, and in cases of extreme Japanese Beetle infestation the surrounding lawn may need to be treated

accordingly. A number of other pests, such as aphids, can harm hops, and can be treated with any number of pesticides.

Since you will be consuming these hops, you should use low toxicity natural pesticides, such as 1% Rotenone dust, for

direct pest control on the plants. As with any consumable, you should ensure that any pesticide is well washed before

using the hops.

Ladybugs are the best, most natural way to get rid of aphids and a lot of other bugs. However, it can be difficult to keep

them on your hop plants once you run out of food for them. A good idea is to plant some cilantro/coriander between

your hop hills. Ladybugs are attracted to this plant and it will keep their attention between feedings of aphids. You can

even harvest the cilantro (the leaves) for cooking and use the coriander (the seeds) in Witbier.

One other hazard is animals. A short fence of rabbit wire will keep cats, dogs, rabbits, etc. at bay, but won't do much

against deer.

Rhizomes are available from an increasing number of sources. American Brewmaster in Raleigh, NC, and Freshops in

Philomath, OR, are all well-known suppliers. Cost is usually a few dollars each. They should be kept in plastic bags,

moist and cold in your refrigerator until they are planted.

Additional information about hop growing can be found in "Homegrown Hops" by David R. Beach. Also, the 1990Zymurgy Hops and Beer Special Issue is devoted to hops and contains an article about growing hops by Pierre Rajotte.

The AHA also has additional hops-oriented publications.


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Dry Hopping

Dry hopping can be defined as adding hops to a cooled wort at sometime during the fermentation process. It can be

thought of as "cold-hopping" or "raw-hopping", as these hops do not "cook" like the kettle hops. It adds a fresh hops

aroma/flavor to the beer which cannot be matched with hop additions into hot wort. It is not to be confused with

finish/aroma hopping, which is done on the hot wort while still in the kettle. The use of a hop-back, where hot wort is

passed through the hops, is another form of finish hopping it is not dry hopping. Dry hopping gives no alpha acids to

the wort, but it may contribute some oxidized beta acids its bittering contribution to the final product is very small. It is

more likely to add a perceived bitterness with the addition of the intense aroma rather than an actual bitterness due tobitter acids.

There are several ways to dry hop, if one considers the variations of making hop teas, etc. The best time to dry hop is

after primary fermentation has slowed and little CO2 is being driven off the wort. Dry hopping earlier than this point is

inefficient as the volatile hop oils are scrubbed away by the exiting CO2. Also, dry hopping early in the fermentation

phase may result in hops on the bottom of the fermenter being covered with yeast, which results in inefficient extraction

of aroma. Another consideration of timing dry hopping is with infection risk. Hops in contact with boiling wort are

effectively sanitized. Addition of dry hops after primary fermentation allows them to contact a wort/beer with some

alcohol and less sugar, which prevents infections from getting a foothold.

The proper length of time for dry hopping is dependent on the temperature. At ale temperatures, 7-14 days of contact

time is widely used. At lager temperatures, although little data is available as few lagers are dry hopped, it seems obvious

that longer contact times, on the order of 14-21 days, are called for. It is common to use 0.5 - 2.0 oz. or more in a 5

gallon batch, but as always it is up to the individual's preferences and the hop variety. An ounce or more of East Kent

Goldings in the secondary will add a nice aroma, but probably not overpowering to most brewers. A similar amount of

Cascades, on the other hand, are not for the faint of heart! The rare commercial brewer that dry hops generally leaves the

hops on the beer for a longer time than the average, impatient homebrewer. This is undoubtedly to extract more aroma

from this relatively expensive ingredient.

EKGs, Fuggles, Northern Brewer, Saaz, Cascade, all Hallertauer variants, and many other hops have been used

successfully. It should be noted that the aroma of the beer greatly influences the profile, and that the "correct" aroma hop

should be used to match the style (i.e. English hops for English ales). American brewers have traditionally used hops

from all over the globe so European hops, for example, can be used without fear of a brewing faux pas. Note also thattraditionally, German beers are not dry-hopped, but that American versions of German styles are sometimes dry hopped.

The first and foremost way to dry hop is to simply put the hops into the fermenter. The most common worry with this

method is about infecting a beer which is nearly ready to bottle/keg. Hops are natural preservatives, and infections from

this method are very rare. Of course, an infection source in a homebrewery is impossible to prove, but this risk is

certainly minimal. If loose hops or plugs are used, they will float, and some brewers use a sanitized hop bag and marbles

to sink the hops for maximum contact. If pellets are used they will sink, but may be difficult to avoid when bottling or

kegging. Also, the pellet hops can be easily covered by yeast falling out of suspension, so they should be added after

virtually all fermentation activity has ceased, and a good amount of the yeast has fallen. Finally, it is worth mentioning

that, for many, pellets are not well regarded for dry hopping because the pelletization process is known to be very rough

on the volatile aromatic compounds which the brewer is attempting to capture. Others swear by them, claiming the pre-

burst lupulin glands provide more aroma to the beer.

Another method used to dry hop is to steep the hops in a white alcohol (grain, vodka, etc.) and sometimes water solution

for hours or days, then pour this solution into the fermenter. This is a common practice among those who want to protect

against the remote possibility of infection with normal dry hopping. It should be noted that as the temperature of the

alcohol/water/hops mixture is raised, the effect approaches that of finish hopping, as the most volatile hop oils are driven

off.

Adding hop oil, a product recently introduced to the homebrewing market, is another way of "dry-hopping". It should be

done after primary fermentation has slowed for many of the same reasons.

These dry hopping methods, and others, will produce different results, mainly because the desired compounds are sovolatile. The variety of reactions taking place during processing and fermentation will affect the results. Some have noted

grassy and otherwise unpleasant aromas from the practice of dry hopping, so it is not for all beers, nor for all people. The

"best" method is the one which gives the desired result to the individual homebrewer.
http://www.northernbrewer.com/


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A final note about dry-hopping: the volatile hop compounds will react quickly with oxygen. For this reason, extra

measures should be taken to avoid mixing with air during bottling or kegging, in order to retain the hop aroma for

extended periods of time. These extra measures may include purging the bottling vessel and keg with CO2, very quiet

siphoning, oxygen scavenging caps, and possibly delayed capping after bottling. This method allows any CO2 coming

out of solution during the bottling process to push the oxygen out of the bottle before the caps are secured. This method

is used by many homebrewers but, as always, the results are inconclusive. The simplest method is to use the oxygen

scavenging caps, which requires no extra effort and little extra cost. For further reference, the Summer 1993 "Zymurgy"

contains an article by Mark Garetz on this subject.

What is a "Hop-back"?

A homebrewer's hop-back is a reservoir connected in-line between the kettle and counter-flow chiller. It is filled with

fresh hops before the flow is started. The hot wort flows through the fresh hops and is quickly chilled by the counter-

flow before entering the fermenter. Many of the volatile hop aroma compounds are extracted and brought into the

fermenter with this process. It is generally thought to produce a flavor/aroma profile somewhere between late kettle

additions and dry-hopping. A good article by Kinney Baughman on building a hop-back is in the "Zymurgy" Gadgets

and Equipment Special Issue, and another, written by Charlie Stackhouse, is in the Fall 1994 "Zymurgy" edition.

Wet vs. Dried Hops?

Yes, you can but at best it is a rough guess as to how much. The rule of thumb is to use 6 times as much (by weight) as

you would dry hops. A safer rule would be to do this and to only use them for finish/dry hopping. Since these hops have

not been tested, the AA% is unknown, and later additions are less sensitive to AA%. It should be noted that some

homebrewers have had mixed results when using fresh hops (poor AA approximation for bittering, sometimes grassy

aroma for finishing).

High Alpha vs. Low Alpha

Will high alpha acid hops contribute the same type of bitterness as low alpha acid hops? The short answer is: probably

not. The longer answer has to do with the oils and resins in the hops. As previously stated, hops bring much more tobeer than bittering. There are different qualities of bittering and many respected brewers agree that a cleaner, smoother

bitter can be attained by using an equal number of IBUs from a low alpha hop. To quote George Fix: "I have always

had a strong preference for low alpha aroma hops, even for early additions for bittering. I find that they give (if fresh!) a

clean and mellow bitter, which contrasts with the crude effects I pick up from high alphas." According to Fix, Narziss et

al cited the ratio of the hop oils alpha-humulene/myrcene as providing a refined flavor, with higher ratios (> 1.5)

providing a positive effect. Fix followed this up with research on the hop resins, and showed that hops with < 30%

cohumulone (as a percent of alpha acids) were preferred. The correlation between the two (oils vs. resins) has not been

shown, but as in all areas where human perception is involved, proof is difficult. The bottom line: bitterness is not all the

same.

Hop Varieties and How to Use ThemDISCLAIMER: Hop substitutes should generally be thought of as "last resort" options. Some of them work better than

others, and of course, the individual brewer must decide which substitutes are best. No attempt was made here to label

"good" and "not-so-good" substitutes, because the opinions vary wildly.

Aroma Hops

The following hops are generally considered aroma hops although in recent years they have started to gain a following

in the homebrew community for bittering as well:

Name: CASCADEGrown: USProfile: strong spicy, floral, citrus (especially grapefruit) aromaTypical use: bittering, finishing, dry hopping for American style alesExample: Sierra Nevada Pale Ale, Anchor Liberty Ale & Old FoghornAA Range: 4.5 - 8%


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Substitute: Centennial

Name: CHALLENGERGrown: UK (Northern Brewerheritage)Profile: spicy aroma, fruity flavorTypical use: dual purpose, aroma and bittering, blends well with other hopsExample: ???AA Range: 6.5 - 8.5%Substitute: ???

Name: CRYSTAL (CFJ-HALLERTAU)

Grown: USProfile: mild, pleasant, slightly spicyTypical use: aroma/finishing/flavoringExample: ???AA Range: 2 - 5%Substitute: Hallertauer Mittelfrueh, Hallertauer Hersbrucker, Mount Hood, Liberty.

Name: EAST KENT GOLDINGSGrown: UKProfile: spicy/floral, earthy, rounded, very mild aroma; spicy (candy-like?) flavorTypical use: bittering, finishing, dry hopping for British alesExample: Samuel Smith's Pale Ale, Fuller's ESB

AA Range: 4.5 - 7%Substitute: BC Goldings, Target

Name: ULTRA (was EXPERIMENTAL 21484)Grown: USProfile: fine aroma hopTypical use: finishing for German style lagersExample: NoneAA Range: 3 - 6%Substitute: Hallertauer Mittelfrueh

Name: FUGGLESGrown: UK, US, and other areasProfile: mild, soft, grassy, floral aromaTypical use: finishing / dry hopping for all ales, dark lagersExample: Samuel Smith's Pale Ale, Old Peculier, Thomas Hardy's AleAA Range: 3.5 - 5.5%Substitute: East Kent Goldings, Willamette

Name: HALLERTAUER HERSBRUCKERGrown: GermanyProfile: pleasant, spicy/mild, noble, earthy aromaTypical use: finishing for German style lagersExample: Wheathook Wheaten AleAA Range: 2.5 - 5%Substitute: Hallertauer Mittelfrueh, Mt. Hood, Liberty, Crystal, NZ Hallertau Aroma

Name: HALLERTAUER MITTELFRUEH

Grown: GermanyProfile: pleasant, spicy, noble, mild herbal aromaTypical use: finishing for German style lagersExample: Sam AdamsBoston Lager, Sam AdamsBoston LightshipAA Range: 3 - 5%Substitute: Hallertauer Hersbrucker, Mt. Hood, Liberty, Crystal, NZ Hallertau Aroma

Name: LIBERTYGrown: USProfile: fine, very mild aromaTypical use: finishing for German style lagersExample: Pete's Wicked LagerAA Range: 2.5 - 5%

Substitute: Hallertauer Mittelfrueh, Hallertauer Hersbrucker, Mt. Hood, Crystal

Name: LUBLINGrown: PolandProfile: Reported to be a substitute for noble varieties, in fact is
http://www.samadams.com/http://www.samadams.com/http://www.realbeer.com/cgi-bin/realbeer/cust_redir.cgi?27273&http://www.merchantduvin.com/pages/5_breweries/samsmith.htmlhttp://www.realbeer.com/cgi-bin/realbeer/cust_redir.cgi?27273&http://www.merchantduvin.com/pages/5_breweries/samsmith.htmlhttp://www.northernbrewer.com/


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said to be Saaz grown in Poland.Typical use: aroma/finishingExample: ???AA Range: 2 - 4%Substitute: Saaz, Hallertauer Mittelfrueh, Hallertauer Hersbrucker, Tettnang, Mount Hood, Liberty, Crystal.

Name: MT. HOODGrown: USProfile: mild, clean aromaTypical use: finishing for German style lagers

Example: Anderson Valley High Rollers Wheat Beer, Portland AleAA Range: 3.5 - 8%Substitute: Hallertauer Mittelfrueh, Hallertauer Hersbrucker, Liberty, Tettnang

Name: NZ HALLERTAU AROMA (an organic version also exists)Grown: New ZealandProfile: Said to be a replica of German Hallertauer MittelfruehTypical use: fine aroma hoppingExample: Coors, Coors LightAA Range: 6 - 8%Substitute: Hallertauer Mittelfrueh, Hallertauer Hersbrucker, Tettnang, Crystal

Name: PROGRESSGrown: UK (Whitbred Goldings heritage)Profile: similar to Fuggles, but slightly sweeterTypical use: bittering and aroma for British alesExample: ???AA Range: 5.0 - 7.5%Substitute: Fuggles

Name: SAAZGrown: CzechoslovakiaProfile: delicate, mild, floral aromaTypical use: finishing for Bohemian style lagersExample: Pilsener UrquellAA Range: 2 - 5%

Substitute: Tettnang (many would claim there is NO substitute)

Name: SPALTGrown: Germany/USProfile: mild, pleasant, slightly spicyTypical use: aroma/finishing/flavoring, some bitteringExample: Common in Dusseldorf AltbiersAA Range: 3 - 6%Substitute: Saaz, Tettnang

Name: STRISSELSPALTGrown: France -- Alsace areaProfile: medium intensity, pleasant, similar to HersbruckerTypical use: aroma/finishingExample: ???

AA Range: 3 - 5%Substitute: Hersbrucker, German Spalt

Name: STYRIAN GOLDINGSGrown: Yugoslavia (seedless Fuggles grown in Yugoslavia), also grown in USProfile: similar to FugglesTypical use: bittering/finishing/dry hopping for a wide variety of beers, popular in Europe, especially UKExample: Ind Coope's Burton Ale, Timothy Taylor's LandlordAA Range: 4.5 - 7Substitute: Fuggles, Willamette

Name: TETTNANG

Grown: Germany, USProfile: fine, spicy aromaTypical use: finishing for German style beersExample: Gulpener Pilsener, Sam AdamsOctoberfest, Anderson Valley ESBAA Range: 3 - 6%Substitute: Saaz, Spalt
http://www.samadams.com/http://www.realbeer.com/cgi-bin/realbeer/cust_redir.cgi?953&http://www.widmer.com


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Name: WILLAMETTEGrown: USProfile: mild, spicy, grassy, floral aromaTypical use: finishing and dry hopping for American / British alesExample: Sierra Nevada Porter, Ballard Bitter, Anderson Valley Boont AmberAA Range: 4 - 7%Substitute: Fuggles

Bittering Hops

The following hops are generally considered bittering hops, but some aroma applications have been noted (note that the

examples given may not enlighten the taster as much as the aroma hops in the previous section):

Name: BREWER'S GOLDGrown: UK, USProfile: poor aroma; sharp bittering hopTypical use: bittering for alesExample: Pete's Wicked AleAA Range: 8 - 9%Substitute: Bullion

Name: BULLIONGrown: UK (maybe discontinued), USProfile: poor aroma; sharp bittering and blackcurrant flavor when used in the boilTypical use: bittering hop for British ales, perhaps some finishingExample: ??? (GuinnessExtra Stout and SSWW - not confirmed)AA Range: 8 - 11%Substitute: Brewer's Gold, Pacific Gem

Name: CENTENNIALGrown: USProfile: spicy, floral, citrus aroma; clean bittering hop (Super Cascade?)Typical use: general purpose bittering, aroma, some dry hoppingExample: Sierra Nevada Celebration Ale, Sierra Nevada Bigfoot Ale

AA Range: 9 - 11.5%Substitute: Cascade

Name: CHINOOKGrown: USProfile: heavy spicy aroma; strong versatile bittering hopTypical use: bitteringExample: Sierra Nevada Celebration Ale, Sierra Nevada StoutAA Range: 12 - 14%Substitute: Galena, Eroica, Nugget, Bullion

Name: CLUSTERGrown: US, Australia

Profile: poor, sharp aroma; sharp bittering hopTypical use: general purpose bittering (Aussie version used as finishing hop)Example: WinterhookChristmas AleAA Range: 5.5 - 8.5%Substitute: Galena, Cascade, Eroica

Name: EROICAGrown: USProfile: clean bittering hopTypical use: general purpose bitteringExample: Ballard Bitter, BlackhookPorter, Anderson Valley Boont AmberAA Range: 12 - 14%Substitute: Northern Brewer, Galena

Name: GALENAGrown: USProfile: strong, clean bittering hopTypical use: general purpose bitteringExample: Catamount Porter, Devil's Mountain Railroad Ale
http://www.northernbrewer.com/http://www.realbeer.com/cgi-bin/realbeer/cust_redir.cgi?708&http://www.redhook.comhttp://www.realbeer.com/cgi-bin/realbeer/cust_redir.cgi?708&http://www.redhook.comhttp://www.guinness-webstore.com/


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AA Range: 12 - 14%Substitute: Northern Brewer, Eroica, Cluster

Name: NORTHERN BREWERGrown: UK, US, Germany (called Hallertauer NB), and other areas (growing region affects profile greatly)Profile: fine, fragrant aroma; dry, clean bittering hopTypical use: bittering and finishing for a wide variety of beersExample: Old Peculier(bittering), Anchor Liberty(bittering), Anchor Steam(bittering, flavoring, aroma)

AA Range: 7 - 10%Substitute: Hallertauer Mittelfrueh, Hallertauer Hersbrucker

Name: NUGGETGrown: USProfile: heavy, spicy, herbal aroma; strong bittering hopTypical use: strong bittering, some aroma usesExample: Sierra Nevada Porter & Bigfoot Ale, Anderson Valley ESBAA Range: 12 - 14%Substitute: Chinook

Name: PERLEGrown: Germany, US

Profile: pleasant aroma; slightly spicy, almost minty bittering hopTypical use: general purpose bittering for all lagers except pilsenerExample: Sierra Nevada Pale Ale, Summerfest, and Pale BockAA Range: 7 - 9.5%Substitute: Hallertauer Mittelfrueh, NZ Hallertau Aroma

Name: PRIDE OF RINGWOODGrown: AustraliaProfile: citric aroma; clean bittering hopTypical use: general purpose bitteringExample: Foster's Lager, Victoria Bitter, Coopers Sparkling AleAA Range: 9 - 11%Substitute: ???

Hard to Find Hops

The following hops are relatively rare. In fact, they are rare enough that I haven't found much useful information on

them, but they are included here for completeness.

Name: GREEN BULLETGrown: New ZealandProfile: ???Typical use: Bittering and aroma in lagers, even pilsenersExample: ???AA Range: 8 - 12%

Substitute: Styrian Goldings

Name: NORTHDOWNGrown: IrelandProfile: good flavor and aroma, blends well with other UK typesTypical use: all purpose ale hopExample: GuinnessAA Range: 7.2 - 9%Substitute: Target, Northern Brewer

Name: PACIFIC GEMGrown: New ZealandProfile: delicate black currant/floral noseTypical use: Strong Bittering, but also some aroma applications

Example: ???AA Range: 14%+Substitute: Bullion?

Name: SOUTHERN CROSSGrown: New Zealand
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Profile: ???Typical use: Strong Bittering and fine aroma qualitiesExample: ???AA Range: 11-12%Substitute: ???

Name: STICKLEBRACTGrown: New ZealandProfile: Said to be comparable to European Northern BrewerTypical use: Strong Bittering as well as aroma usesExample: ???

AA Range: 11 - 13%Substitute: Northern Brewer

Name: SUPER ALPHAGrown: New ZealandProfile: ???Typical use: bittering and aroma applicationsExample: Steinlager, Hahn PremiumAA Range: 10 - 13%Substitute: ???

Name: TARGETGrown: UKProfile: accounts for 40% of UK hop production

Typical use: mostly used for bittering, some aroma potentialExample: Young's Special London AleAA Range: 10.5 - 12.5%Substitute: Northdown, Progress

Contributors

Glenn Anderson ([email protected])

Scott Barrett ([email protected])

Jeremy Bergsman ([email protected])

Jim Busch ([email protected])

Nick Cuccia ([email protected])

John DeCarlo ([email protected])

David Draper ([email protected])

Alan Edwards ([email protected])

George Fix ([email protected])

Bill Flowers ([email protected])

Jeff Frane ([email protected])

Mark Garetz ([email protected])

Russ Gelinas ([email protected])

Mark Kellums ([email protected])

Al Korzonas ([email protected])

Rick Larson ([email protected])

Don Leonard ([email protected])John Palmer (palmer#d#[email protected])

Bob Regent ([email protected])

Peter Soper (not online?)

Spencer Thomas ([email protected])

Glenn Tinseth (gtinseth (at) yahoo (dot) com)

Rich Webb ([email protected])

Patrick Weix ([email protected])

Carl West ([email protected])

Ed Westemeier ([email protected])

Dave Wiley ([email protected])

Gene Zimmerman ([email protected])

Business catalogs referenced
http://www.realbeer.com/library/authors/palmer-j/http://www.northernbrewer.com/http://www.northernbrewer.com/


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Just Hops--Mount Zion IL

HopTech--Danville, CA

Hopunion USA--Yakima, WA

Further Reading

Kinney Baughman

"Zymurgy" Gadgets and Equipment Special Issue, 1992

David R. Beach

Homegrown Hops

George Fix

"Science in the Service of the Brewer's Art", National Homebrewer's Conference Transcripts, 1994.

Mark Garetz

"Zymurgy" Summer 1993,

"Brewing Techniques" Jan/Feb 1994,Using Hops, The Complete Guide to Hops for the Craft Brewer , 1994

"All About Bittering", National Homebrewer's Conference Transcripts, 1994.

Alfred Haunold & Gail Nickerson

"Brewing Techniques" May/June 1993

Charlie Papazian

The New Complete Joy of Homebrewing

Dave Miller

The Complete Handbook of Homebrewing

Jackie Rager

"Zymurgy" Hops and Beer Special Issue, 1990

Pierre Rajotte


Quentin B. Smith


Charlie Stackhouse

"Zymurgy" Fall 1994

Glenn Tinseth

"Brewing Techniques" Jan/Feb 1994

Send feedback to: gtinseth (at) yahoo (dot) com
http://brewingtechniques.com/http://brewingtechniques.com/http://brewingtechniques.com/http://www.belgianbeer.com/http://www.hopunion.com/


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http://www.realbeer.com/hops/http://realbeer.com/

Documents

Calculos de IBU