Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1 PROCESS FOR PRODUCING A MORE STABLE MALT BEVERAGE
2 AND PRODUCT PRODUCED THEREFROM
3
4 The present invention relates to the production of malt beverages
having improved flavor-stability. The invention has particular utility in the
6 production of fermented malt beverages such as beer and will be described in
7 connection with such utility, although the invention also may be
8 advantageously used in the production of other malt derived beverages.
9 In the production of beer, a warm water extract of barley malt, ~~ith or
without other unmalted grains such as rice or corn, is .boiled with hops,
11 cooled, and then subjected to the fermentative action of yeast. The warm
12 eater used to extract the malt allows the action of several enzymes in the
malt
13 to hydrolyze the starch in the barley (and in the corn or rice) to
fermentable
14 sugar.
As a result of material contained in the ingredients, or the mashing
16 process, or the fermentation process, or a combination of two or more of
the
17 above, malt beverages are subject to an oxidative change in flavor. The
18 resulting flavor is variously described as papery, cardboard-like, stale,
or just
19 plain "oxidized". This flavor change typically takes place within 2-3
months
of room temperature storage, and is gradual and continuing. Most American
21 manufacturers of beer recall beer from the market if it is more than about
4
22 months from the packaging date. Although the oxygen in a bottle or can of
23 beer is typically consumed by the beer within less than 24 hours after
24 packaging, the noticeable presence of oxidized flavor generally does not
appear until many weeks later.
26 The flavor of oxidized malt beverages generally is attributed to
27 unsaturated aldehydes notably traps-2-nonenal, and related compounds.
28 These compounds are thought to be derived from unsaturated fatty acids,
29 which split and then lose two hydrogen atoms. This loss of hydrogen is a
form of oxidation.
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1 The present practice of delaying the staling of beer is to maintain a low
2 level of air (or oxygen) in the packaged beer, storing the beer at cold
3 temperatures, and/ or by the addition of sulfites, within legal limits,
prior to
4 packaging.
Modern beer-filling machines are designed to achieve very low air
6 levels in the packaged product. Typically, the present practice is to
evacuate
7 the bottle before it is filled with beer, or to replace the air in the
evacuated
8 bottle with carbon dioxide before filling, and to cause overfoaming in the
9 bottle to displace the head space gases with beer foam. All of these
practices
can produce air levels of less than 0.5 ml. per 12 oz. bottle. But even these
low
11 levels of air still allow beer to oxidize in 2-3 months.
12 Another technique for stabilizing beer against oxidation is to add
13 sulfur dioxide, in the form of bisulfite, to the beer. However, in the
United
14 States, addition of sulfur dioxide is limited by law to less than 10 ppm,
and
even those low levels produce undesirable and sulfury aromas in some beers.
16 Also the bisulfite, which works by binding to aldehydes, has many other
17 aldehydes in beer to bind to (notably acetaldehyde, a normal by-product of
18 fermentation), and so its action is often muted. Other countries such as
19 Germany prohibit any addition of sulfur dioxide.
In my prior U.S. Patent No. 5,455,052, I describe a method of improving
21 the stability of a malt beverage to oxidation, which comprises adding to
the
22 malt beverage about 0.01 to about 50 parts per million, by weight, of a
lactone
23 selected from the group consisting of gamma-nonalactone-gamma-
24 undeclatone, and mixtures thereof. While the addition of a lactone to a
beer
as above-described advantageously has been found to stabilize beer against
26 oxidation, the addition of a lactone (or other ingredients) is frowned upon
by
27 beer purists, and is prohibited under the brewing purity laws in countries
28 such as Germany.
2
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I It is thus a primary object of the present invention to provide a process
2 for enhancing the flavor stability of a malt beverage. A more specific
object of
3 the present invention is to provide a malt beverage in which oxidative
flavor
4 does not begin to appear for many months of storage.
I have found that the exposure of malt beverages to dried, toasted oak
6 wood ( uercus alba and/or uercus robus), in particulate form, i.e. shavings,
7 chips, powder or other small entities, for a period of from one day to
several
8 weeks, provides flavor stability to the malt beverage for periods up to one
9 year or longer.
Further objects and advantages of the invention. shall be apparent from
11 the following detailed description, taken in connection with the
12 accompanying drawing, Fig. 1, which illustrates a preferred embodiment of
13 the present invention, in partial cross-section.
14 The exposure to the oak wood particles is done after the main
fermentation, during the aging process, but also may be done before or after
16 the standard aging stage. The aging process may be conducted in any of the
17 three standard aging methods - simple lagering (allowing fermented beer to
18 be stored for several days or weeks in a tank); second fermentation
(removing
19 the settled yeast from a fermenting tank before the fermentation has been
completed and allowing fermentation to slowly proceed to or near the limit of
21 fermentation); or krauesening (treating of freshly fermented beer with a
small
22 portion, about 15% by volume, of beer that just started fermenting a day
23 before). The addition of the oak wood particles preferably is done at the
24 inception of the aging process.
When using oak wood particles in accordance with the present
26 invention, the wood particles should be wood, as it comes form a tree i.e.
the
27 oak wood particles should not be washed with detergent or other alkaline
28 solution, nor steamed, and the oak wood particles should not be coated,
e.g.
29 with wax or pitch. Moreover, the oak wood particles should be used for a
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1 single batch, and discarded. On the other hand, the oak wood particles must
2 be dried and toasted in air, under controlled conditions, i.e. at a
temperature
3 between about 300°F and about 500°F, to a moisture content of
about 0.5%to
4 1 % by weight, preferably about 1 % by weight, prior to use. In order to
ensure low moisture content prior to use, the oak wood particles preferably
6 are stored in an airtight container after toasting. Also, the dried oak wood
7 particles, which have low density and poor wetting characteristics, tend to
8 float on the foam on top of the beverage as the tank is being filled. In
order to
9 ensure intimate and lasting contact between the oak wood particles and the
beverage, the oak wood particles preferably are loosely packaged in a porous
11 or permeable fabric bag or container which is weighed down with a dense
12 material such as glass, stainless steel or other dense material which is
inert to
13 the beverage, such that the wood-particle containing bag or container sinks
in
14 the tank or remains suspended in the beverage, but does not float to the
top.
Alternatively, the wood particle-containing bag or container may be tied to a
16 cleat on the side or bottom of the tank, or to a cooling coil or the like
in the
17 tank, or the container may be tied to an anchor.
18 The flavor stabilizing improvement appears to be dependent upon the
19 quantity of oak wood particles added. Thus, the oak wood particles should
be added in an amount of about 0.05 lbs. per 100 lbs. of malt beverage (or
0.13
21 lbs. per bbl. of malt beverage). Addition of less than about 0.01 lbs. per
100
22 lbs. of malt beverage (or 0.03 lbs. per bbl. of malt beverage) appears to
result
23 in little improvement in flavor stability. On the other hand, addition of
more
24 than about 0.8 lbs. per 100 lbs. of malt beverage (or 2.0 lbs. per bbl. of
malt
beverage) appears to result in little additional improvement in flavor
stability.
26 The reason why the addition of oak wood particles to a malt beverage
27 improves flavor stability is not known. However, while not wishing to be
28 bound by theory, it is known that oak contains various organic acids,
4
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1 aldehydes and phenols and tannins, one or more of which may impart the
2 oxidation -- stabilizing effect in beer.
3 Historically, and to a lesser extent today, beer was/is stored in wooden
4 tanks of cypress, chestnut or oak. However, direct contact of the beer with
the
wood was/ is scrupulously avoided by coating the wood, for example, with a
6 paraffin-type wax or pitch. This is because the contact of wood with beer
has
7 been found to cause microbiological problems and musty flavors in the beer
if
8 the wood is not coated and re-coated as time goes on. Thus, it was/is
9 common for wooden tanks used in breweries to be re-coated annually or bi-
annually to prevent such contact and ensuing microbiological problems in
11 flavors. In the United States and most other countries, stainless steel
largely
12 has replaced wood for beer containers today. Wooden barrels also once were
13 used to deliver beers to bars. However, such wooden barrels typically were
14 re-coated every time they were returned to the brewery. Today, wooden
barrels have essentially been completely replaced by stainless steel barrels.
16 Moreover, aging or storing the beer in wooden tanks or casks does not
17 provide the desired and unexpected stabilizing result in any event.
18 A major U.S. brewery claims to use beech wood chips in its aging
19 process. However, such chips are used only after they have been washed
with caustic solutions to remove any soluble material from the wood. And,
21 these chips, which are used many times and washed after every use, are used
22 merely to serve as mechanical supports, i.e. provide more surface area, for
23 action of the yeast which settles on the chips.
24 Toasted, dried oak wood ( uercus alba and/or uercus robus)
appears to be unique in stabilizing beer against oxidation. Other wood
26 particles have been tested and are found not to provide a similar effect.
27 The flavor stabilizing improvement appears to be independent of the
28 size and form of the oak wood particles; however, for a given weight,
smaller
29 particles appear to require a shorter residence time to achieve the desired
5
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1 result. It is believed that this is because the smaller particles have a
relatively
2 larger surface area which facilitates extraction of the materials which
impart
3 the oxidation stabilizing effect in accordance with the present invention.
The
4 toasted oak wood particles should be used to process a single batch, and
removed, and discarded.
6 The resulting malt beverage has superior flavor stability over similar
7 malt beverages made without the addition of toasted oak wood particles, and
8 none of the disadvantages of undesirable and sulfury aromas common to
9 prior art techniques for stabilizing beer against oxidation by the addition
of a
bisulfite.
11 The present invention will be further described in the following
12 working examples.
13 White oak wood chips ( uercus alba) were prepared by planing white
14 oak stock. The chips were placed in an oven and heated to 300-500~F for
about 30- 90 minutes, until they were browned slightly, and the moisture
16 content measured about 1 % by weight. The toasted chips 10 were allowed to
17 cool, packaged in a porous cotton bag 12 to which was added sufficient
18 stainless steel shot 14 as ballast to overcome any buoyancy of the wood
chips.
19 The cotton bag was then tied closed at 16, and the bag placed in a plastic
storage bag 18 pending use as described below in the following working
21 examples.
22 Preparation A was repeated, however employing red oak particles
23 (Quercus robus) and glass beads as ballast.
24 EXAMPLE I
Twenty-five thousand Tbs. of barley malt were ground and added to
26 200 bbls. of water at 122°F in a mash tub. After resting for 20
minutes, the
27 temperature was raised to 165°F and held for 40 minutes. It was then
brought
28 to 175°F and the mash transferred to a Tauter tub and filtered.
6
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1 The filtered wort, about 520 bbls., was boiled with 200 lbs. of hops for
2 one hour.
3 The wort was cooled, aerated, and pitched with yeast, in a fermenting
4 tank, where it remained for 7 days.
It was then transferred to an aging tank, in which had been placed 4
6 cotton mesh bags, each filled with 30 lbs. of toasted white oak particles
and 1
7 1/4 lbs. of stainless steel saddles, and tied closed. Then 500 bbls. of beer
was
8 pumped into the tank and the tank closed. It was allowed to remain for two
9 weeks.
The tank was emptied, the beer filtered and finished. The bags of oak
11 were removed, and the stainless steel saddles removed and the oak
discarded.
12 The beer was packaged and subjected to accelerated aging at 100°F
for
13 45 days. The beer was tasted by a panel trained to detect and rate
oxidation in
14 beer. On a scale of 0 to 5, with 5 being thoroughly oxidized, the control
beer
was rated 5 and the oak-treated beer was rated 1.
16 EXAMPLE II
17 Twelve thousand lbs. of corn grits and 1,000 lbs. of malt were added to
18 150 bbls. of water at 120°F, allowed to remain there for 10 minutes
and then
19 heated to boiling and boiled for 30 minutes.
In another vessel,15,000 lbs. of barley malt were added to 200 bbls. of
21 water at 120°F, allowed to rest for 20 minutes, and then the boiling
corn mash
22 was added to it. The temperature was kept at 160°F for 35 minutes
and then
23 raised to 170 °F and transferred to a lauter tub and filtered.
24 The wort was cooled, aerated, pitched with yeast and allowed to
ferment.
26 At the end of fermentation, the beer 500 bbls., was transferred to an
27 aging tank to which had been added 150 lbs. of toasted red oak chips (1
28 moisture) and 50 lbs. of glass beads, separated into three porous woven
nylon
29 bags, and tied closed.
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1 After 18 days, the beer was moved to another tank and filtered. The
2 three bags and oak chips were discarded, after the glass beads were
recovered
3 and washed.
4 The filtered beer was packaged in 12 oz. Bottles and subjected to the
same accelerated aging as in Example I.
6 The results of tasting with the same trained taste panel were the same.
7 Certain changes may be made without departing from the scope of the
8 invention herein involved. For example the porous container could comprise
9 a perforated stainless steel container, in which case ballast may not be
required. Also, the container may include one or more ties or eyelets shown
11 in phantom at 18 and 20, respectively, for tying the container down to the
12 tank, and/or to an anchor (not shown). It is therefore intended that all
matter
13 contained in the above description shall be interpreted as illustrative and
not
14 in a limiting sense.
8
