Bob - 208-371-7757
Easy to order
- Fresh hops are
available as early as late July through the end of August,
depending on Mother Nature.
- Whole dry hops flowers are baled and available
by bale after harvest, by advance preorder only.
- Pellet hops, vacuum sealed in 5 and 10 pound
bags, are available for the current year’s crop about six
to eight weeks after the end of harvest.
- Hops infused oil for salads and for cooking is
available by request as well.
- Certified Organic Rhizomes are available
beginning early February to get your garden or hopyard
The Fire of Bobanero Brew
Michigan hop growers and to provide
Michigan breweries and home-brewers with the best hops in the
Director of Sales and Marketing
496 Pine Meadow Rd.,
Northfield, MA 01360
Ph: 413-498-2968; F: 413-498-4308
craft beer industry and a genuine love
of hops. Working direct with hop growers around the globe we're able
to supply an extensive, and growing list of varietals at competitive
I signed up Bob........
above please visit www.NikoBrew.com for
your hops needs
How to Get - and Keep -
Your Hops' Optimum Value
BrewingTechniques' January/February 1994.
Most brewers are
familiar with the fragile nature of hops - they loose their
bittering qualities over time, and their essential oils degrade.
Accurate information about how and why hops lose their a-acids,
and sound preventive measures like good packaging and storage, can
enable brewers to keep their hops fresh and their brews in line
with expectations. Simple calculations can also help brewers
predict the a-acid levels in their hops at any point in time.
Hops have three main ingredients of relevance to brewers:
a-acids, b-acids, and essential oils. Brewers normally concern
themselves with only two of the three - a-acids and oils.
The a-acids are bitter but dissolve poorly in wort, so they need
to be changed into a form that dissolves well. In brewing, this
change occurs through boiling; the process is known as
isomerization. The resulting isomerized a-acids are more soluble
in wort and retain their bitterness. For all intents and purposes,
b-acids are not bitter and are not changed into a bitter form
during the brewing process. They do form bitter compounds when
oxidized during storage (1).
The oils are responsible for
the aroma of hops and enter into the beer's flavor profile when
added for short boil times, when steeped, or when added fresh in a
hop back or as dry hops in the fermentor.
All three of
these components undergo changes as hops age.
Harvesting and Processing
Hops are harvested once a year,
beginning in mid-August and continuing through early September,
depending on the hop variety. The hops are dried, and in the
United States baled in 200-lb bales. The bales are made by
compressing the hops and then wrapping them in burlap. Some hops
are ground and extruded into pellets. Some hops in the UK are
compressed into "plugs" that weigh about 1/2 oz. The level of
compression in these plugs is much higher than in the bale. (In
the UK, these plugs are known as pellets, technically Type 100
pellets.) In Germany, some hops are compressed into 5-kg (11-lb)
"bricks" and then vacuum sealed. The level of compression of both
of these is about 3-4 times that of U.S. bales.
The hops are
then stored in huge warehouses at about -3 degrees C (~26 degrees
F) (temperatures differ depending on the broker and outside
temperature) and remain there until they are shipped to a brewer
or hop supplier. Most small brewers buy enough hops at the start
of the hop season to last all year, but they are stored at the hop
broker and shipped to the brewery periodically, providing the
brewer the convenience of not needing a huge cold storage
facility. Also, because most small brewers lack hop analysis
equipment, the hop broker can keep tabs on the a-acid and oil
contents as they change over time.
Hops start to lose their a-acids and oils as
soon as they are harvested. The rate of loss depends on the
storage temperature, the amount of air present, and the hop
variety. The lower the temperature, the less the hops deteriorate.
It has been shown that the rate of loss halves for every 15
degrees C (27 degrees F) drop in temperature (2).
definitely bad for a-acids; their oxidation components are
responsible for the "cheesy" aroma detected in old hops (1).
Oxidized a-acids lose their bitterness and cannot be isomerized.
Because b-acids form bitter compounds when they are oxidized, some
believe that this result of oxidation makes up for the loss of
b-acids. In fact, it has been argued that cold storage and
anaerobic conditions are not necessary for bittering hops, as long
as the boil is long enough and open enough to allow the cheesy
aroma to escape. But brewers aren't buying the argument (who can
The variety of the hop also plays a major role
in storage. Hops are usually classified as kettle or bittering
hops and aroma hops. Kettle hops have a higher a-acid content than
aroma hops, and their storage properties are more important. Under
identical storage conditions, certain varieties will lose more
a-acids than others. Each hop variety contains differing amounts
of natural antioxidants, and some varieties' lupulin glands are
more permeable to air than others.
One common test for the
storageability of the hops is to measure the amount of a- and
b-acids lost over a 6-month period at 20 degrees C (68 degrees F).
There is a direct relationship between the losses and the hop
storage index (HSI). The HSI is a number obtained by
spectrophotometric determinations of the a- and b-acids (3,4). If
you know the present a-acids content and the HSI or the percentage
lost figures for a particular variety, you can estimate the
original and future a-acids content. Formulas for predicting
a-acid losses are presented later in this article.
also deteriorate and oxidize over time. Some people believe that
some oxidation of the oils is beneficial to hop aroma. Not enough
research has been done in the area of characterizing the oil
content loss rates for various varieties, so we are unable to
accurately predict oil losses on a variety-by-variety basis at
this time. One could make the assumption that the rate of oil loss
is directly related to the loss of a-acids and use the a-acid loss
formulas to predict the oil losses as well. But again, due to the
lack of experimental data to back this method up, it remains only
Exposure to light hastens hop deterioration
as well. At home, this is not much of an issue because most
freezers are dark inside. But in your local homebrew supply store,
a display freezer may have fluorescent lights in it. Although this
certainly makes the hop display more attractive, the hops would be
better served if the light were removed.
For optimum preservation of hops' valued qualities,
they should be stored as cold as possible (30 to -5 degrees F, or
-1 to -21 degrees C) and away from air. The compression of hops
into bales, pellets, and plugs helps protect all but the surface
layers from air. Even so, air penetrates and causes some
oxidation. Cold temperatures slow the oxidation process. Because
some hop varieties don't store as well as others, at some point in
the season hop brokers take all remaining unsold bales of
poor-storing hops and turn them into pellets. Not only do pellets
keep out a lot of oxygen, their compact form allows them to be
easily vacuum packed to further slow the deterioration.
reason pellets are so prevalent in the home brewing trade is that
they deteriorate more slowly than whole hops when stored in less
than ideal conditions. Microbrewers like them for two additional
reasons: they are easy to remove from the wort if the brewery uses
a whirlpool separator, and they take up much less storage space,
making it much more practical to keep them cold.
compression of whole hops slows the oxidation because it is harder
for the oxygen to get at the hops, when the bale is broken up to
be portioned into homebrew-sized quantities the compression is
lost and air can get at the hops much more easily. Because of the
compression, plugs are a good compromise between pellets and whole
Hop Packaging for Sale to Home brewers
Vacuum packing and inert-gas packaging in an oxygen-barrier
material are the best packaging methods. The common type of
oxygen-barrier packaging is the "boiling bag" which is clear and
made from a lamination of two types of plastic. The inner layer is
a food-grade polyethylene (the same material that common plastic
sandwich bags are made from). Although it does provide a barrier
to water, polyethylene is not a proper oxygen barrier; it does
make a good heat seal, which is the main reason it is used. The
outer layer is made from polyester (also known as mylar or nylon)
and is what provides the barrier layer. The next step up in
effectiveness is the aluminized mylar bag (also known as the foil
bag or pouch), which adds a layer of aluminum that increases the
barrier protection more than 10-fold. It also more than doubles
the cost, so it is not widely used despite its advantages.
suppliers sell hops in simple polyethylene bags, which provide
almost no barrier protection. Hops that have been insufficiently
protected offer dubious a-acid values and should be approached
with skepticism or not used at all.
To tell the bags apart,
think about what a typical sandwich bag feels like; it is made of
polyethylene. You can smell the hops right through it (this should
tell you something). It also has a slightly frosted appearance and
lacks the polished look of polyester. Clear barrier bags are
noticeably stiffer and thicker. They are also shiny and polished
looking and lack the frosted look of polyethylene bags. Foil bags
are usually either silver or gold in color.
Do When You Get Them Home
First, if the hops are improperly
packaged (and you had no choice but to buy them) you need to get
them in suitable barrier packaging as soon as possible. If you're
going to brew with them soon and are going to use them all up in a
few weeks or so, however, don't worry about it - just put them in
the freezer and use them up quickly.
If the hops were properly
packaged, don't open them until you need to. Store them in the
freezer. Once you've opened them, the biggest problem is what to
do with the remainder. If they came in a vacuum-sealed or
nitrogen-flushed bag, the best thing to do is reseal the bag with
a home-quality vacuum sealer, which can cost anywhere from $20 on
sale to $100, depending on the seal width and length and the
amount of heat it puts out. Even the cheapest sealer (available at
many discount outlets) will put out enough heat to seal standard
clear barrier bags. Unfortunately, they may not put out enough
heat to seal aluminized bags. Look around in kitchen supply
departments and hardware stores. Your best bet is to take an old
piece of bag with you and see how it seals. Although you can
transfer the hops to the bags that come with the sealer, beware
that the bags that come with the cheaper models may not be true
barrier bags, though they are better than polyethylene. For
replacement bags, I recommend the bags that come with the Dazey
Micro-Seal system (Dazey Corp., Industrial Airport, Nebraska).
They are true oxygen-barrier bags.
If you keg your beer or
otherwise have carbon dioxide or nitrogen available, you can flush
mason jars with the gas, put the hops in, and add a layer of gas
and reseal the jar. An alternative container is a PET plastic jar
like the ones peanut butter comes in. I advise you to practice
with the gas first because it's very easy to blast your hops all
over the room, and always use a regulator. If you can't do any of
this, put the hops in a mason or PET jar and put them in the
freezer - it's better than nothing.
How Long Will
Like most things in brewing, the answer is, "It
depends." If you keep them very cold and free from oxygen, hops
should last a few years. It's not uncommon for hop brokers to be
selling pelletized and vacuum-sealed hops from two or three
seasons ago. Commercial breweries continue to use last year's crop
well into the current year's harvest. This is not to say that the
oils and a-acids will be exactly the same as when you purchased
them, but the hops won't be "bad"; hops are not considered "bad"
until they get below 50% of their original a-acid value (5), at
which point the degree of oxidation will produce a definitely
Predicting a-Acid Loss
published research (such as the literature referenced in this
article) and the known storage properties of commonly used hops,
it is possible to predict the a-acid content of your hops at any
given point in time. To do this, you must know the following: •
hop variety and its associated storage properties
accurate a-acid percentage for the hops when you bought them
storage conditions (aerobic or anaerobic)
• the storage
• and the number of days from the date at which
you knew the a-acids to the time for which you are predicting
them. To perform the calculations, you must have access to a
scientific calculator, a spreadsheet program with logarithm
functions, or logarithm tables (available in many math and
scientific reference books).
As previously mentioned, hop
storage properties depend on the variety. The data can be reported
in any of three ways, each based on the HSI. The first and least
common way is the actual HSI number. This is rarely encountered in
the hop trade and is primarily used as an in-house reference at
research centers' hop laboratories and large breweries. Hop
brokers publish the storage qualities as either "percent alpha
remaining" or "percent alpha lost" after 6 months of storage at 20
degrees C (68 degrees F). The calculations presented in this
article use the latter method, which I simply call "percent lost."
If you have the "percent remaining" figure, simply subtract it
from 100 to get the percent lost.
surround the accuracy of the a-acids level shown on the packaging
at the point of purchase. When were the hops harvested? How were
they handled and stored? Fortunately, the packaging itself may
tell a large part of the story - high-quality packaging and care
in storage reflects care and concern for the product and lends
reassurance that the labeled values are reliable.
of the required data is readily available from your kitchen or
brewery, depending on your storage conditions. Make no assumptions
about how cold your freezer is. It is a wise and important
investment to get a freezer thermometer and measure it.
determine the "number of days from the date at which you knew the
a-acid percentage," consider the day on which you bought the hops
to be Day 1. If you bought the hops 1 month ago, it is now Day 30.
If you want to know what they will be 1 month from now, that will
be Day 60, and so on.
Step-by-step Instructions for
Predicting a-Acid Losses
To make the math a bit easier,
this article provides some of the values already calculated for
you. All you need to do is look them up in a table. For those who
want to know all of the gory details, the formulas and procedures
used to derive the table values are provided in the accompanying
The first step is to look up the percent lost for the hop
variety in Table I. Next we need to determine the rate constant
(k) based on the percent lost. This rate is the constant used in
the log expression to determine the curve of percent lost vs.
time. Find the percent lost on Table II and next to it the value
for k. Now find the temperature factor (TF) from Table III, based
on your storage temperature. From Table IV, find the storage
factor (SF) based on your storage method. Last, determine the
number of days from the day on which you knew the a-acid content
to the day on which you need to know the new a-acid content
(Days). The a-acid percentage when we bought the hops is referred
to as A.
Now use the following formula:
future alpha =
where e is the base of the natural
logarithm. In Excel and other spreadsheet programs, e(n) is
expressed as EXP(n). Let's walk through an example. Let's say we
bought some Cascade hops at 6.4% a-acid 1 month ago and we want to
brew with it 1 week from today. We're storing it in our home
freezer, which is ~10 degrees F, in its original nitrogen-flushed
oxygen barrier packaging. Table I shows that Cascade's percent
lost value is 50%. Table II reveals that a percent lost of 50%
gives the value for k as 0.00385. Table III shows that the
corresponding value for TF is 0.228, and Table IV shows that the
value for SF is 0.5. We bought the hops 30 days ago, and adding
the 7 days from now, the value for Days becomes 37.
formula now looks like this:
future alpha =
which gives us 6.3% (rounded),
which really isn't all that much different but proves that good
storage conditions can really make a difference in a poor-storing
hop like Cascade. If we stored it at room temperature in a poly
bag the numbers would look like this:
future alpha =
which equals 5.6% alpha - a much more
significant difference. It also shows the effect of poor storage
The hop variety, storage
temperature and storage conditions all play a role in determining
how fast a-acids are lost from the hops. Of these, temperature is
the most important factor over which we have control. Next is hop
variety and finally the aerobic or anaerobic storage conditions.