The present invention relates to rapid, continuous, highly uniform,
chill processing of alcoholic beverages at or near their freezing points, without
any substantial collateral freeze-concentration thereof; and especially in connection
with the production, by way of example, of fermented alcoholic beverages such as
wine, and cider, but especially of fermented malt beverages such as beer, and
low-alcohol and non-alcoholic products derived therefrom.
BACKGROUND OF ART:
Many such beverages can benefit from or even require chilling in
order to preserve or achieve some beneficial attribute. This is especially the
case, given the extreme ability of humans to discern even trace amounts of volatile
and flavour components, as well as cloudiness or "haze" that forms in some such
beverages. Wine beverages for example, can benefit, and specifically so in cases
which require remedial processing to deal with, say, excess tartrate concentrations.
Brewery beverages, or fermented malt brewery beverages in particular,
are of particular interest because of the special benefits to be accrued by way
of "chilling". The general process of preparing fermented malt beverages, such
as beer, ale, porter, malt liquor, low and non-alcoholic derivatives thereof, and
other similar fermented alcoholic brewery beverages, hereinafter referred to simply
as "beer" for convenience, is well known. As practiced in modern breweries, the
process comprises, briefly, preparing a "mash" of malt, usually with cereal adjuncts,
and heating the mash to solubilize the proteins and convert the starch into sugar
and dextrins. The insoluble grains are filtered off and washed with hot water
which is combined with the soluble material and the resulting wort boiled in a
brew kettle to inactivate enzymes, sterilize the wort, extract desired hop components
from added hops, and coagulate certain protein-like substances. The wort is then
strained to remove spent hops and coagulate, cooled and pitched with yeast, and
then fermented. The fermented brew known as "green" or "ruh" beer is then "finished",
aged - which is sometimes referred to as "lagering" and clarified, filtered, and
then carbonated) to produce the desired beer.
A variation on the basic process which is now well recognized is
termed "high gravity brewing" in which procedure the green beer is produced at
an elevated alcohol content (say for example from 7 to 8% v/v, and this is then
diluted to the alcohol content desired in the finished beer (eg. 5% v/v for a "regular
As is well known, beers in general develop a haze over time and/or
through changes in temperature of the beer. This haze is considered to be made
up of two types:
- (a) "chill haze" which is temperature sensitive and may disappear as the temperature
of the beer is raised to, say, room temperature; and
- (b) "permanent haze" which, as the name implies, once created, remains.
Of course, if a beer is consumed warm, as is customary in some European
countries, then chill haze may not be as serious a problem for the brewer and consumer
as it otherwise would be for beers that are customarily consumed cold, (as is
typically the case for North American beers, for example).
In any event, the problem of chill haze manifestation has been exacerbated
by industry trends that have resulted in an increase in the amount of time that
normally elapses between when the beer is finished, and when it is finally consumed
by the public. As a consequence the haze has a greater opportunity to develope
to a problematic and often unacceptable degree.
The exact nature and mode of formation of haze in beer is still uncertain
but it is generally accepted that haze comprises significant amounts of proteins,
yeast cells, metals, cell components, polyphenols and various other materials.
The problem of haze formation has been addressed in many ways over
many years. The traditional way, of course, is to subject the beverage to a conventional
"lagering" step over the course of which the beverage is stored at near zero temperatures
for periods of time ranging from weeks to, in extreme cases, up to several months.
During this step of the process the yeast cells, proteins, etc., settle out and,
all things going well, the taste of the beer may also improve; the beer is said
Conventional lagering, however, is not proving to be adequately proactive
in keeping pace with the increasing chill-haze problem that results from the longer
post-finishing pre-consumption time period mentioned above. Moreover, the time,
capital and operating cost commitments associated with the lagering process, account
for a significant proportion of the overall brewery costs. Accordingly, significant
effort continues to be expended in the search for ways to deal with the chill
haze problem, and to find better and less time-consuming alternatives to lagering
Examples of the results of such efforts include the use of polyvinylpyrrolidone
(PVP) to stabilize beer by combining with the polyphenyls, which use this is well
documented, refer to U.S. Patents 2,688,550; 2,939,791 and others.
U.S. Patent 3,251,693 teaches adding various silicates particularly
calcium, magnesium or zinc silicates to the beer (or wort) and U.S. Patent 3,940,498
teaches the use of certain acid treated synthetic magnesium silicates. For example
U.S. Patent 3,940,498 teaches adding an acid-treated synthetic magnesium silicate
to the beer.
Although these methods do alleviate aspects of the chill haze problem,
they by no means eliminate it or replace the lagering process. Moreover these solutions
are becoming less favored in the industry, as the use of additives or processing
aids in foods becomes less popular with consumers.
Improvements in beverage stability have been mentioned as ancillary
benefits in the extensively explored freeze concentration processes. For example,
Canadian Patent No. 673,672 involves freezing beer to produce a slurry of concentrated
beer, ice and other solids including yeast cells, removing the ice and other solids
from the desired concentrated beer, which has concentrated up to five-fold relative
to the starting beer. The ice is discarded or passed into a system to recover
beer or desirable components entrained thereof on the ice. All freeze concentration
processes suffer from the fact that the ice removed can carry away some of the
desired material and recovery of that material which is occluded or retained on
the ice, by washing extraction or other means, brings its own problems - refer
for example to Canadian Patent No. 710,662. Also, the practical process is usually
multistage with successive stages being effected at temperatures reduced relative
to earlier stages, this procedure being quite common in the freeze concentration
art - refer for example to Canadian Patents No. 601,487 and No. 786,308. This latter
patent has the same inventor and proprietor as Canadian Patent No. 673,672 and
covers products produced by the latter patent. Despite the quite amazing claims
made for the products produced under this patent, it does not seem to have ever
been commercially exploited. U.S. Patent No. 4,885,184 teaches a process for preparing
flavored malt liquors wherein an aged fermented wort is freeze concentrated generally
to the 20% to 30% alcohol by volume level, and various flavorings are then added.
Quite apart from the claims that have been made for accelerated aging
and improvements in beverage stability in the freeze concentrated products, there
are significant and in some cases insurmountable problems that arise out of collateral
concentration of the beer. First of all it is illegal in many jurisdictions to
concentrate by distillation or otherwise any alcohol-containing substrate without
a distillers or other appropriate license. There is also a fundamental question
over whether the product of such a distillation can legitimately be labeled as
"beer" at all. Moreover, the stability of freeze concentrated beers appears to
be very much in doubt or at least suspect, notwithstanding the various claims
that may have been made to the contrary. While any number of attempts have been
made to produce concentrated beer products, many have been faced with product
instability, as exemplified by work done at the Institute of Brewing Research Laboratories
(Essery, Cane and Morris, Journal of the Institute of Brewing,
53, No. 4; Essery and Cane, ibid., 1952, Vol.58, No.2, 129-133; and Essery,
American Brewer, 1952, Volume 85, No. 7, 27, 28, and 56). As described in
the cited articles, when the concentrated beer was stored and then diluted back
to its original concentration, the reconstituted product tasted decidedly weak
and under-hopped, so that freeze concentration seemed to cause considerable loss
of palate-fullness and loss of bitterness. The cited articles also indicate that
storage of the concentrate also often actually led to the production of haze and
a vinous flavour in the beer. In the freeze concentration process described in
Canadian Patent No. 872,210 the unfermented wort which is freeze concentrated,
this apparently providing efficiencies in obtaining a higher yield or extract from
the brew materials than is obtained in a regular brew. Because the process is
not carried out on an alcoholic substrate, distillation is not an issue. With regard
to chill haze, however, any predisposition of a beer to elicit chill haze which
is engendered as a result of the fermentation process, will not be addressed by
freeze concentration process called for in this Canadian
Another proposal that avoids the problems of distilling an alcoholic
beverage, is set out in Australian Patent Specification 224,576. This patent suggests
batch freezing a beer to create a slush ice condition. This condition is maintained
for up to seventy-two hours and is followed by melting the beer and immediately
separating out any precipitated materials. However it is appreciated that the beer
contains material which redissolves before it can be removed in the normal course
by filtration or centrifugation and consequently the pre-freezing addition of a
general adsorbent material such as asbestos or bentonite appears from the teachings
of the patent to be critical to the process, so that the precipitated material
- eg chill haze material - is adsorbed onto the insoluble additive, before it can
redissolve upon melting of the slush. This approach, however, falls back into
the problems associated with the use of processing aids and additives as mentioned
above, and in particular runs head-long into the prohibition against
any food-related use of asbestos in particular. Also, the need to maintain
a frozen mass of beer for any protracted period of time appears to be faced with
many of the same shortcomings that attend conventional lagering. Moreover, and
notwithstanding the collocation of the ice and the beer throughout this process,
the fact remains that the aqueous component of the beer is frozen and the balance
of the beer is held in a concentrated state. However temporary that condition may
be, the fact is that this process necessarily entails concentrating the beer,
and is in this connection, merely a batch processing version that is otherwise
similar to the continuous process that is described in US 3,295,988 -. Malick.
In both the Australian patented process and the Malick process, the beer is concentrated
for a period of time, and then the large amount of frozen aqueous component is
melted into the concentrated beer to form the reconstituted beer product from
Malick - the developer of the so-called Phillips freeze concentration
process, was preeminent in attempts to commercialize freeze concentration technology
in beer related applications. According to Malick, (in the article "Quality Variation
In Beer" The Brewer's Digest, April 1965), accelerated lagering is caused "because
it takes place in a concentrated state". That being the case, the prior art teaches
that actual concentration of the beer is a prerequisite to achieving accelerated
lagering (with any claimed attendant physical stability benefits).
As indicated above, the occurrence of haze in beer and the management
of the lagering process are, obviously, still significant practical problems for
the brewing industry, despite the extensive efforts and diversification of the
preferred solutions from the past.
Moreover, and notwithstanding Malick's above-quoted assertion that
actual concentration is a prerequisite, the present invention has surprisingly
revealed that in fact there is no substantive requirement for concentration to
take place, and that benefits previously thought to be associated with concentration
can be achieved substantially in the absence of such concentration. Moreover, in
the case specific of beer, additional advantages with respect to hop flavour retention
are realized in applications of the present invention that are not in evidence
in the prior art freeze concentration processes.
As indicated, the above detailed discussion centers around alcoholic
brewery products and the problems specific to fermented malt beverages. However,
there is a need in the alcoholic beverage industry to provide rapid, uniform cooling
of alcoholic beverages, usually during processing, to their freezing points, without
running the risk of actually freezing to liquid to the point where it cannot be
readily handled (ie pumped).
DISCLOSURE OF INVENTION:
Accordingly, there is provided a process for chill-treating a fermented
malt beverage. This process comprises subjecting the beverage to a cold stage
comprising rapidly cooling the beer to a temperature of about its freezing point
in order to form ice crystals therein only in minimal amounts. The resulting cooled
beer is then mixed for a short period of time in slurried relation with ice crystals.
This is effected without any appreciable increase in total ice crystal mass contained
in the resulting mixture during said mixing, (i.e. concentration of the beer under
treatment is avoided). Finally, the so treated beer is extracted from the mixture.
The process as a whole can be carried out without any substantial collateral concentration
of the beer. Preferably, the said resulting cooled beverage is mixed with a residual
volume of ice crystals in said aqueous slurry.
The process of the present invention as set forth in the preceding
paragraph differs markedly from the various processes with utilize freeze concentration
processes, even if relatively temporarily in some instances. In freeze concentration
processes, the "cold-stage" processing step is carried out specifically for the
purpose of maximizing the production of small "subcritical" crystals in the aqueous
liquid. When admixed as a suspension with larger, "supercritical" ice crystals,
the mean bulk temperature of the liquid equilibrates to an intermediate value in
the range of the respective melting points of the various ice crystals in the
resulting suspension. Since the mean average temperature is higher than the melting
temperature of the smaller "subcritical" crystals, most melt. The thermodynamic
energy redistribution results in collateral crystalline growth of the larger, "supercritical"
ice crystals and these have to be continuously removed, as more of the same continue
to grow. This thermodynamic behavior drives the overall increase in the ice mass,
and stands at the very heart of most commercial freeze concentration processes.
(Note: "supercritical" and "subcritical" crystals, in the present context, are
art-recognized terms - see CRC Critical Reviews, in Food Science and Nutrition,
Volume 20, Issue 3, page 199.
By way of contrast, to the above described freeze concentration processes,
the present invention, broadly speaking, is distinguished in that such subcritical
ice crystal growth as there may be in a near-freezing flow of beverage, is thermodynamically
balanced against supercritical ice crystal melting in the flow-through reactor
(eg a "recrystalizer"), such that there is (on average) no appreciable interim
increase in the concentration of the aqueous flow stream as it traverses the treatment
zone, ( ie although from time to time the amount of ice in the recrystalizer vessel
- mentioned elsewhere herein - may be adjusted by controlling the amount of refrigeration
that the incoming liquid is subected to the overall effect avoids collateral concentration).
This helps to avoid problems in the art that are associated with beverage properties
following concentration and reconstitution to the desired beverage - refer in
particular, to the detailed disclosure herein as it relates to beer. Accordingly,
the concentration of the beverage as processed in accordance with the present
invention undergoes at most only very nominal, and in general only extremely transient
increases. This is the very antithesis of freeze concentration processing, where
the very objective of processing is entirely the reverse.
In a preferred form, the process of the present invention is adapted
for chill-treating a volume of an alcoholic beverage, in which the liquid medium
of the post cold- stage resident volume of stable-ice-crystal-in-aqueous-liquid
slurry comprises the same alcoholic beverage and the treated liquid solution is
drawn off in a volume equal to the original volume.
In a continuously operated embodiment, the present process facilitates
continuously chill-treating by subjecting a volumetric flow of pre-treatment beverage
to the cold and post-cold-stages mentioned above, and drawing-off treated potable
aqueous liquid solution in a equal volumetric flow.
In particularly preferred applications of the present process, the
resident volume of stable ice crystals in the same beverage are about 10 to about
100 times larger than the nascent ice crystals contained in the incoming cooled
The treat process according to the present invention can be carried
out at any post-fermentation stage of the brewing process at large, and while preferably
done prior to or in place of any signifigant aging steps, it is also entirely
possible to conduct the present chill treating process following some intermediate
The process is generally applicable in respect of malt beverages,
and too, relates more generally to the preparation of fermented cereal beverages
(and especially distilled beverages). In that latter case, the process includes
the steps of fermenting a cereal-containing substrate to produce an ethanol-containing
liquid; distilling or otherwise concentration the ethanol-containing liquid to
produce a distillate having a predetermined ethanol concentration; and, subjecting
the said ethanol-containing liquid or the resulting beverage to the aforementioned
chill-treatment. Examples of fermented cereal beverage production include the group
consisting of: all malt;
mixtures of rye and malt; mixtures of corn, rye and malt; mixtures of rye, wheat
and malt; corn; and, rice. These are employed in known manner in the production
of the corresponding beverages: scotch; rye; bourbon; Irish whiskey; grain alcohol;
and, Arrak, respectively.
Additionally, the present process can be employed in the treatment
of comestible aqueous liquids, and in particular a potable aqueous liquid, and
especially beverages, which are generally azeotropic mixtures. Typically, such
a liquid will, in every substantive respect, be a binary azeotropic aqueous mixture
containing alcohol, and in general, the alcohol will be ethanol.
Similarly, the process of the present invention extends to the preparation
of fermented wine beverages comprising crushing grapes; separating the pommace
and must; fermenting the must to produce a wine; and racking-off precipitated
tanins, proteins, pectins and tartrates. In accordance with the present process,
either or both the must or the resulting wine is subjected to the above described
chill-treatment. Fruit wines, produced by similar known methods may be similarly
treated according to the present invention.
In like manner, the present invention extends to the production of
a fermented rice wine beverage produced by generally known procedures, and usually
comprising saccharifying polished rice with amylolytic enzymes to prepare an aqueous
mash; acidifying the mash containing fermentable sugars produced through the action
of said enzymes on the rice; fermenting the fermentable sugars contained in the
acidified mash with an acid-tolerant yeast to produce rice wine; and, finally subjecting
the resulting rice wine (sake) to the chill-treatment as specified herein.
Moreover, alcoholic cider produced by the usual and well known methods
may also be further processed according to the present invention.
However, the especially preferred form of the present invention relates
to a process for preparing malt brewery beverages, and in particular, fermented
malt brewery beverages.. In accordance with this aspect of the invention, there
is provided a process comprising mashing brewing materials with water; heating
the resulting mash and separating wort therefrom; boiling, cooling and fermenting
the wort; and, subjecting the resulting beer to the chill-treatment as specified
herein. Prior to chill-treating, it is particularly advantageous that the yeast
cells be generally substantially removed from the fermented wort since an excess
residual of cells may be ruptured during the treatment and the breakdown products
produce off-flavors and possibly contribute to physical instability of the product.
Following such removal, it is preferred that less than about half a million yeast
cells per ml remain in the fermented wort. In one embodiment, the fermented wort
be degassed (in known manner) prior to chilling in accordance with the present
As is generally well known, the alcohol content and solids content
of any given beer will effect the freezing point. It is, however, contemplated
that for most commercial purposes, the application of the present invention will
generally involve cooling the brewed green beer to in the range of -1ºC
to -5ºC. For beers that are produced in accordance with otherwise
conventional, contemporary North American brewing practices, the brewed green
beer will typically be cooled to in the range of -2ºC to -4ºC,
preferably -3ºC to -4ºC.
Rapid cooling helps to ensure that only nascent ice crystals develop
- these being relatively small and unstable. Preferably, cooling is effected in
generally less than 60 seconds, preferably in about 30 seconds or less, and especially
in about 5 seconds or less.
Typically, this will generate a minor amount of nascent ice crystals
during the cooling, for example, generally in an amount of less than 5% by volume
of said brewed green beer. More typically, the nascent ice crystals are formed
in an amount of about 2% or less by volume. The nascent crystals are generally
smaller than about 10 microns in size.
Once the brewed green beer is so cooled, it is then passed immediately
to the ice crystal-containing treatment zone. This zone is completely filled with
a slush-like slurry comprising ice crystals and the green beer. Here, the green
beer undergoes post-cold-stage mixing treatment with a resident volume of generally
stable ice crystals in aqueous liquid slurry. The slurry liquid medium preferably
comprises the same green beer. Also stable ice crystals are preferably of about
10 to about 100 times larger than the nascent ice crystals, ie such stable crystals
are about 100 to 3000 microns in size. The mixture is maintained in a constant
state of agitation to maintain it homogenous.
The proportion of the stable ice crystals in the slurry in the post-cold-stage
resident volume is maintained in an amount of less than 45% by volume. Care should
be taken when using larger proportions, since these can create mechanical mixing
problems, and can interfere with homogeneity of treatment (eg creation of flow
channeling, etc). Control over the amount of stable ice crystals is effected by
way of a feedback signal that is generated in response to signals from ice sensors
arranged in ice-crystal-concentration sensing relation to the post-cold-stage
resident volume of stable-ice-crystal-in-aqueous-green beer slurry. A preferred
conductivity-based sensing device is described elsewhere herein, in greater detail.
Other such sensing devices will be readily apparent to persons skilled in the art,
in light of the present disclosure. In any case, the feedback signal controls
the degree of the preceding, cold-stage cooling of the green beer, to reduce or
increase as required, the amount of nascent ice crystals that are formed therein,
to thereby adjust the proportion of stable ice crystals in said post-cold-stage
resident volume to the desired volume. Typically, the proportion of stable ice
crystals in said post-cold-stage resident volume is maintained in an amount of
less than 35% by volume, generally in an amount of less than 25% by volume, preferably
in an amount of about 5 to 20% and especially in an amount of about 10 to 20% by
volume. However, the amount may be less than 5% provided it is sufficient to maintain
the treatment zone at about the liquid freezing point. This results from the fact
that the stable ice crystals function as a well dispersed, high surface area,
heat buffer, that serves to maintain the surrounding liquid at about its freezing
point. The temperature to which the green beer is pre-cooled, and the residence
time of the beer in the treatment zone are inter-related to the minimum optimal
proportion of stable ice crystals.
Typically, the residence time of the green beer in the post-cold-stage
slurry is less than one hour. Preferably, the residence time of the green beer
in the post-cold-stage slurry is generally up to 15 minutes, and usually about
5 to 15 minutes, but may be less, to as low, for example, as say 1 to 2 minutes.
Following post-cold-stage slurry treatment, the chill treated, green
beer is preferably subjected to inert gas purging in a holding (aging) tank to
remove residual volatiles such as sulphur compounds like mercaptans and thiols.
The "inert" gas (meaning a gas which does not adversely effect the beer), may be
carbon dioxide, or nitrogen. Note that nitrogen in particular, has low solubility
and has no deleterious effect on the liquid, whereas in extreme concentrations,
carbon dioxide is less desirable and potentially deliterious. This purging process
compliments the accelerated "physical aging" (that is facilitated by chill-treating),
by accelerating an aspect of what might be called "flavour aging". The combination
of these processing steps is especially advantageous in reducing the time required
for aging, (and might even be employed to replace conventional aging altogether).
The need for aging is well recognized in the art, and especially
in connection with production of higher strength beers (eg 15 degrees Plato). According
to EP Publication No. 180,442, for example, it is disclosed that:
"The problems of producing higher strength beers do not stop
with fermentation. Long maturation times are required for the removal of "off"
flavors and for the development of acceptable flavors and aromas.
Furthermore, long periods of cold storage are required to stabilize
the beer ... ".
In accordance with one aspect of the processing associated with the
present invention, beer maturation is accelerated by forcing high levels of carbon
dioxide (eg 2.8 to 3.0 volumes) into the chill-treated beer, on its way from the
treatment zone to the ageing or storage tank. The beer is then held in the ageing
tank, and vented over a period of about 24 hours. The aging tank is then sealed,
and monitored to ensure that internal tank pressure does not build up. If the pressure
within the tank does rise materially following sealing, then the beer is again
vented for a further 24 hours. This sealing/venting cycle is repeated as often
as necessary, until tank pressure no longer builds up.
In accordance with another aspect, a "zero" aging process is provided
in which chill-treated beer, while still at near-zero temperatures mentioned earlier,
is passed to a reactor ("a scrubber") and purged with an inert gas, such as nitrogen
gas, then passed straight-away, for packaging, without undergoing significant
Both of the forgoing "accelerated aging" aspects of the present invention
provide the so-called "flavour ageing" mentioned above. Note, however, that the
related improvement in flavour maturation is separate and apart from the qualitative
improvement in hop flavors that have been associated with the chill-treating process,
The present invention is especially useful in conjunction with high
gravity brewing processes. In one regard, the treatment of high gravity green beer
in the chill treatment according to the present invention, improves the reduction
in chill-haze and other precipitable materials as mentioned above. Also typical
breweries have a limited storage capacity in which to hold beer during aging thereof,
and this problem can be made even more acute when using high gravity brewing procedures
if the diluted finished beer must be stored somewhere prior to bottling. Since
the present invention, by accelerating aging, frees up aging tank time, that space
is available to hold beer prior to bottling. Accordingly, carrying out high gravity
dilution only after the chill treatment according to the present invention is
completed, provides a dove-tailing of the high gravity and chill treating processes.
However, if aging tankerage is not a problem, then the chill-treating
process of the present invention may be effected for advantage, subsequent to,
say, a reduced period of ageing in the tanks.
When high gravity brewing is coupled with the process of the present
invention, it is also possible, if desired, to carry out the dilution process during
the chill-treatment, by directing a preferably cold-stage treated, diluent stream,
preferably cooled to a similar temperature (subject always of course to to its
own colligative properties) such that the thermodynamic balance referred to earlier
herein, may be readily maintained, in mixing relation into the high gravity green
beer stream. This may be useful in particular when the diluent is a lower alcohol
green beer, as might be the case when the target alcohol concentration in the
finished beer is intermediate between the respective concentrations in the two
green beer streams. If the diluting stream is not prior cooled, then the temperature
of the liquid must be adjusted accordingly, so that the overall thermodynamic
balance of the present process is preserved.
The chill treatment according to the present invention is also especially
advantageous in the production of non-alcohol and low-alcohol products. The former
contains substantially no alcohol, about 0.01% to 0.05% v/v, whereas low alcohol
products have about 0.5% to about 1% v/v of alcohol. They are generally produced
in one of two ways:
- a) traditionally, by removing the alcohol from a regularly brewed beer by distillation
and more recently by ultrafiltration; or,
- b) by "cold contact" processing where only minimal fermentation is permitted,
such that the alcohol content is at most about 1% v/v and which can be reduced
by further dilution to the desired value, usually about 0.5% v/v (volume/volume).
(Such a process is described in a variety of patents/applications - Japanese Kokai
53-127861, for example, discloses such a process, as do US patents 4,661,355 and
4,746,518, and published Canadian Patent Application 2,027,651. A significantly
improved cold-contact process is disclosed in US patent 5,346,706.
These products have the same haze forming components as regular beers
and this is especially so in the cold contact products. Hence they may be advantageously
processed according to the present invention.
As indicated above it is believed that a reduction, inter alia, in
polyphenol content of the beer contributes to the reduction in the period reburied
for ageing. To illustrate this point, the following evaluation was made:
The present invention was used to produce seven green beer substrate.
Evaluations were conducted according to knownASBC industry standards, to determine
the polyphenol content (mg/L) of the substrate green beer prior, and subsequent,
to the treatment according to the present invention. The results were as follows:
As discussed above, it is considered that a major factor in haze
production is the slow precipitation of polyphenyls over time and hence, the reduction
thereof by the process of the present invention demonstrates the increased stability
of the so treated products as compared with regular beer against chill haze of
the products treated according to the present invention. Moreover, the beer exhibited
desirable flavour characteristics, especially smoothness. It should be noted that
differences in the polyphenol contents are significant.
In accordance with yet another aspect of the present invention, there
is provided a liquid flow-through apparatus for continuously chill-treating an
alcoholic beverage. The apparatus comprises a heat exchanger for cooling the aqueous
solution to reduce the temperature thereof to about its freezing point with only
minimal amounts of nascent ice crystals being formed therein, in combination with
a container or vessel for containing ice, which vessel is interconnected in downstream
serial relation to the heat exchanger, for receiving cooled aqueous solution therefrom.
This vessel includes separator means for passing chill-treated liquid from the
ice container, while retaining stable ice crystals inside of the vessel. The apparatus
further includes retained ice-crystal-concentration monitoring and controlling
means for monitoring and responsively thermally controlling the amount of ice
crystals that are contained in the vessel.
In operation, the heat exchanger rapidly cools the aqueous solution
to a temperature of about its freezing point in such a manner that any nascent
ice crystals are formed therein only in minimal amounts. The resulting cooled
aqueous solution is then mixed in the ice container, for a short period of time,
with a post-cold-stage resident stable volume of ice crystal containing aqueous
slurry. During this mixing the heat balance is feed-back controlled in part by
the above mentioned monitoring and controlling means such that there is no appreciable
increase on average, in the total ice crystal mass contained in the resulting mixture,
and the temperature of the aqueous slurry is maintained (buffered) at near freezing
by the ice mass. Thereafter the treated beverage is extracted from the mixture
through the separator means.
In operation, the retained, stable ice crystal-concentration monitoring
and controlling means monitors the concentration of the stable ice crystals in
the ice vessel and responsive to the monitored condition thereof, thermally regulates
the amount of stable ice crystals contained in said container during the passage
of aqueous solution therethrough.
The liquid is forced through the system under sufficient positive
pressure to facilitate the requisite flow rate through the apparatus.Typically,
the apparatus includes temperature and flow rate control means associated with
the heat exchanger to thereby effect the cooling of the aqueous solution therein.
In a preferred form, this is accomplished in less than about 60 seconds, even
in 30 seconds or less, and even in about 5 seconds.
The separator means is delayed from separating for a period of time
that preferably does not exceed 60 minutes, ( preferably for less than 30 minutes,
and especially for from 5 to 20 minutes).
In one form, the apparatus includes degassing apparatus, serially
interconnected upstream of the heat exchanger, for degassing the aqueous liquid
prior to cooling thereof.
In an especially preferred form, eg for treating brewed green beer,
the heat exchanger is a scraped surface heat exchanger adapted to cool the beer
to near its freezing point, which generally will be in the range of -1ºC
to -5ºC, and especially to in the range of -2ºC
to -4ºC, with the specific temperature in each case depending,
inter alia, on the alcohol and solids content of the beer.
In operation the cooled green beer is then serially passed into the
ice vessel, which adapted to be completely filled with a slurry comprising the
stable ice crystals and the, for example, green beer, which slurry is maintained
in a constant state of agitation by agitation or stirring means (eg more generally
dispersing means) means operable in any case for rendering the distribution of
the slurry in the vessel, homogenous. This agitated condition preferably operates
like a fluidized bed with the ice crystals held uniformly suspended in the moving
The control means preferably maintains ice container resident stable
ice crystals of about 100 to 3,000 microns in size. These are larger by a factor
of from 10 and 100 times, than typical nascent crystals that are contained in
the green beer as it exits from the heat exchanger.
The apparatus hereof preferably has an ice vessel which includes
an insulated housing.
Also, the feedback mechanism operates in response to signals from
ice sensors in or adjacent the treatment zone (eg vessel), to effect a reduction
or increase in the amount of ice contained therein, by ensuring the green beer
is further cooled or is less cooled, respectively, in the heat exchanger. This
is a dynamic, and ongoing adjustment, throughout the process. The proportion of
stable ice crystals is preferably a fixed amount, with a set-point that is usually
established such that about 10% to 20% of the volume of the vessel is maintained
as stable crystals.
Flow rate control means is employed to regulate residence time of
the green beer in the ice treatment zone, and this is preferably of relatively
short duration, eg less than one hour, generally up to 15 minutes, usually 5 to
15 minutes and may be as low as 5 to 2 minutes or less.
In the exemplary embodiment, the present invention provides a process
for continuously processing beer at low temperatures in the apparatus generally
as set forth above. In that connection it has been found that if, in the brewing
process, and preferably prior to aging the temperature of beer is rapidly reduced
to approximately its freezing point in a manner such that only a minimal amount
of crystals are formed, and the so cooled beer is contacted with an agitated slurry
of ice crystals for a relatively short period of time and without concentration
of the beer, the aging stage of the brewing process can be significantly reduced,
and, perhaps, even eliminated. The process of the present invention ensures that
all the beer being treated is invariably subjected to the same low temperature
treatment and hence is uniformly processed and with less risk of the equipment
freezing up and being damaged.
Moreover, the resulting finished beer is smoother, less harsh, and
more mellow compared to regularly processed beer, especially if care is taken to
remove substantially all of the yeast cells emanating from the fermentation from
the green beer prior to it being treated. Moreover, the present invention has been
found to be useful in reducing metallic hop notes but without reducing the bitterness
characters - an advantage which is especially desirable in high "bitterness units
to extract beers", and to highly bittered brews in general. While bitterness is
a characteristic which in greater and lesser degrees, is desirable and even specific
to malt brewery beverages, it can manifest as a metallic note in beers where organoleptically
large proportions of hops or hop extracts are used in the brewing process. This
can be a problem in so-called "no-alcohol and low-alcohol" beers, and low extract
beers. It can also be a problem in beers where very large amounts of bitterness
units are part of the product profile. For example, some beers have bitterness
units specifications that run from 20 BU to as high as 60 BU or more. This reduction
in the metallic taste can be used to advantage in rounding out the desirable bitter
flavour of the beer, without loss of the essential hop character.
Accordingly, there is provided in another aspect of the present invention,
a beer product produced in accordance with the process of the present invention.
More particularly, there is provided an alcoholic beverage, and more specifically
a chill-tempered beer having a thermal history in accordance with which the beverage
was rapidly cooled to a temperature at about its freezing point whereby only sufficient
heat to form minimal amounts of nascent ice crystals therein was extracted, and
whereafter, the resulting cooled beverage was mixed with a volume of ice-crystals
in an aqueous slurry, and the mixture was held for a short period of time, during
which at least a portion of said nascent ice crystals melted but without any appreciable
collateral increase in the total ice crystal mass contained in the resulting mixture;
and, whereafter the resulting chill-tempered beverage was separated from said mixture,
at a total dissolved solids and alcohol concentration that was not substantially
greater than the total dissolved solids concentration of the original, untreated
Generally, therefore, there is provided a chill-tempered beverage
extract from an admixture of a slurry comprising: stable ice crystals suspended
in aqueous liquid; and, an un-tempered beverage having had a minor aqueous proportion
thereof passed through an initial liquid-to-solid state change in the formation
of nascent ice crystals and then through a reverse solid-to-liquid state change
on melting thereof in the admixture without any appreciable collateral increase
in the total ice crystal mass contained in the admixture.
BRIEF DESCRIPTION OF DRAWINGS:
The process of the present invention will be more fully described
but not limited by reference to the following drawings in which:
BEST MODE(S) FOR CARRYING OUT THE INVENTION AND INDUSTRIAL APPLICABILITY:
- Figure 1 is a schematic drawing showing the steps involved in the treatment
of the green beer according to the present invention;
- Figure 2 is a diagrammatic cross-sectional view of a simple pilot plant system
for effecting the cold processing stage, i.e. the cooling and ice-treating the
beer according to the present invention;
- Figure 3 is a flow diagram of a plant adapted to treat green beer according
to the present invention; and,
- Figure 4 is a graphical representation of freezing points for a variety of
aqueous liquid foods, as a function of solids content.
According to a preferred aspect of the present invention there is
provided a process for preparing a fermented malt beverage wherein brewing materials
are mashed with water, the resulting mash is heated and wort separated therefrom,
said wort is boiled cooled and fermented and the green beer is subjected to a finishing
stage, which includes aging, to produce said beverage, comprising additionally
subjecting the beer to a cold stage comprising rapidly cooling said beer to a temperature
of about its freezing point in such a manner that ice crystals are formed therein
only in minimal amounts, mixing said cooled beer for a short period of time with
a beer slurry containing ice crystals without any appreciable increase in the
amount of ice crystals in the resulting mixture, and extracting so treated beer
from said mixture. It may be noted that the extracted beer is generally free of
ice crystals, these having for the most part melted back into the liquid or retained
in the slurry.
In accordance with one aspect of the preferred embodiment of the
invention the substrate beer is green beer and the said treatment is effected prior
to aging thereof.
In a further embodiment therefore, the present invention provides
a process for preparing a fermented malt beverage wherein brewing materials are
mashed with water, the resulting mash is heated and wort separated therefrom,
said wort is boiled cooled and fermented and the green beer is subjected to a finishing
stage, which includes aging, to produce said beverage, comprising prior to aging,
subjecting the beer to a cold stage comprising rapidly cooling said beer to a temperature
of about its freezing point in such a manner that, at most, only ice crystals
of a small size, and in minimal amounts, are produced therein, treating said so
cooled beer for a short period of time in a fluidized bed of ice crystals having
a size greater than that of said small crystals, such that there is no appreciable
rise in the amount of ice, and recovering the so-treated green beer.
In carrying out the process of the present invention the cooling
stage is conveniently carried out in a scraped surface heat exchanger and the mixing
stage, which may comprise mixing the cooled green beer with an agitated slurry
of ice crystals in green beer, may be conveniently effected in what is often termed
in the literature as a "crystallizer" unit which forms part of commercially available
freeze concentration systems. Such a system and associated apparatus are described
for example in U.S. Patent No. 4,004,886 to Thijssen et al, the disclosure of
which is hereby incorporated by reference. As will be readily appreciated, only
a portion of the device described in U.S. patent No. 4,004,886 is used in carrying
out the process of the present invention and that is operated in a very different
manner to that taught in that reference. Essentially, it is used to provide a treatment
zone containing an amount of an agitated slurry of preferably larger ice crystals
which maybe considered to function as a fluidized bed in which the beer is treated
as it passes therethrough, the amount of crystals in the "bed" does not appreciably
increasing throughout the process. The treated beer is separated from the ice crystals
which remain in the treatment zone, until, periodically, following from at the
end of each brewing cycle during which generally from 1,200 to 15,000 hectoliters
or beer are treated, the ice crystals are removed and discarded. Again, it may
be noted that the majority of the crystals entering the recrystalizer are relatively
small and, as explained above, are removed by melting.
Initially, the process can be initiated by adding the, preferably
relatively larger crystals (usually having an average size of from 100 to 3,000
microns) in "bulk" to the treatment zone or, conveniently, they can be generated
in situ by introducing the cooled beer into the zone and, over a period
of time, under conditions in which the preferably relatively smaller ice crystals,
which comprise only about 5%, and usually about 2% of the beer volume, will grow
and produce the desired amount of larger crystals in the zone. Thus relatively
short start-up phase for generation of the stable ice crystal containing slurry
is preferred but is not critical to the present invention.
It has been found that when the treatment zone operates in an efficient
steady manner when it contains about 20% to 25% and preferably 10 to 20% by volume
of said crystals although amounts of from 35% to 5% or even less by volume of
said crystals may be used depending on, for example, the type of beer being treated.
The specific amount may vary slightly during processing but any such variances
are monitored and a feedback system is arranged to instruct the heat exchanger
or equivalent cooling system to increase or decrease, as required, the temperature
of the cooled green beer to re-balance the system. Such systems, e.g. based on
determination of the ice content by electric conductivity, are readily available.
It has been found that the above system functions in an efficient
manner if the green beer, usually exiting the fermenter at say 10ºC
to 17ºC is cooled to between about -1ºC to 5ºC
and is then passed through the scraped surface heat exchanger or other suitable
cooling device where it is cooled to as low as about -5ºC, usually-4.5ºC
to -1ºC. That same temperature is generally maintained in the
The actual freezing temperature of the beer substrate and hence the
temperature attained in the cooling zone depends on a number of factors including
the beer composition, Plato value, but especially the alcohol value. For example,
with a green beer having a Plato value of about 16ºP as is routinely
the case in high gravity brewing, and an alcoholic content of about 7% to 7.5%
alcohol by volume, the green beer is advantageously cooled to a temperature of
about -4ºC before being introduced into the treatment zone. The
higher the alcohol content, the lower the temperature which will generally be
required to achieve the product having the desired characteristics.
It should be noted that the two components of this specific system,
the heat exchanger and the treatment vessel, except at start-up) operate full of
liquid medium and hence there is no need to provided an inert atmosphere which
would otherwise have been required.
A major advantage of the present invention is its capability to be
carried out in a continuous manner without the ice-containing treatment zone becoming
inoperative because of buildup of ice coats cooling tubes and similar items in
cooling systems making them less efficient, and renders control of the system very
difficult and in the extreme case clogs the system, a problem with the various
prior art processes.
In the following, a preferred treatment of green beer prior to aging
is described, although it is possible to effect the cold stage treatment post aging
if desired, (assuming that an ageing step is being used at all).
Turning to FIG 1, wort from a lauter tun (not shown) passes through
line 10 to fermentation vessel 12 where it is pitched with yeast and fermented
in the usual manner. Following completion of the fermentation, the spent yeast
is removed by centrifuge 13. Man's usual normal methods of removing the yeast
cells may leave a minor amount of yeast cells in the green beer. However, these
residual cells have been found to have adverse effects on the finished beer, it
is thought due to their being lysed in the ice treatment according to the present
invention and the resulting cell fragments have adverse effects on the organoleptic
properties of the finished beer.
Consequently, it is much preferred that extra care be exercised and if necessary,
more efficient separating equipment utilized to remove substantially all of the
yeast prior to the green beer being treated according to the present invention.
The brewed green beer is then rapidly cooled in a scraped surface
heat exchanger 14 where cooling to the freezing point of the beer is effected,
this will generally be in the range of -1ºC to -5ºC,
normally -2ºC to -4ºC depending on many factors
including the specific alcohol content. In this case, it was -3.7ºC.
The cooling is effected in a short period, generally less than 60 and usually
a few seconds. A minor amount of small crystals are formed, less than 5%, generally
2% or less by volume as was the case in this instance,, the treatment being adapted
to prevent the growth of large crystals or an excessive amount of small crystals
(considered to be less than about 9-10 microns). In fact, less than about 2% of
the volume of the beer is converted to ice in the cooling stage. The so cooled
beer is then passed immediately to the ice-containing treatment zone 15. This zone
is completely filled with a slurry comprising of ice crystals and the green beer,
which slurry is maintained in a constant state of agitation to render it homogenous.
The ice crystals are preferably significantly larger in size, by a factor of from
10 and 100 times, than the crystals contained in the beer being treated. The treatment
zone has a combination of insulation around the zone and a feedback mechanism in
according with which, in response to signals from ice sensors in the treatment
zone, a reduction or increase in the amount of ice is corrected by ensuring the
green beer is further cooled or is less cooled, respectively. Thus the objective
of maintaining a fixed amount usually about 10% to 20% or 22% of the volume of
the zone as larger crystals is maintained as is the temperature of the treatment.
The ability to consistently maintain the low processing temperatures without the
ice clogging and damaging the system is a critical aspect of the present invention.
The ice treatment zone may, simply initially be loaded with the body of ice crystals
but more conveniently, these are produced in situ upon startup of the system
by running the heat exchange unit in such a manner as to produce major amounts
of small crystals which are allowed to grow to the desired size in the treatment
zone. Loading the zone in this manner may take from about one to several hours,
usually about 2, depending on many factors including the type/capacity of heat
exchanger used and the alcohol content of the green beer. This start-up phase
is not considered to be part of the continuous operational phase of the chill-treating
process described herein.
The residence time of the green beer in the ice treatment zone is
relatively short, less than one hour, generally up to 15 minutes, especially 5
to 15 minutes only, and may be even less, following which, the treated beer is
transferred to aging tank 16. It is then finished in the usual manner.
This system is elegantly practical in that:
- (a) it is not complex; there are no counter-current flows and, in fact, only
one and uni-directional flow, namely the fluid substrate being treated and hence
requires minimal equipment and is simple to operate;
- (b) the treatment does not involve concentration of the green beer and hence
there is no constant removal of ice crystals (these requiring only their being
discarded at the end of a brewing cycle). Obviously, the ice is not subsequently
treated in any manner, there being so little of it relative to the amount of beer
treated, that there is virtually no entrained beer, etc., associated with it.
- (c) it is a process stage which gently processes the green beer at a high rate
and is readily and conveniently incorporated into present brewing processes with
little disruption to existing plant layouts;
- (d) it is a continuous and rapid process thereby incurring small additional
cost but delivering beneficial results as far as desirable product characteristics
are concerned, especially a significant increase in chill stability as well as
very positive organoleptic properties;
- (e) using the equipment described, both the heat exchanger and the separation
vessel are full with liquid medium and hence do not require maintenance of an
inert or carbon dioxide atmosphere, except on start-up and up to the time the vessel
Turning to FIG 2, this shows a pilot plant for a beer cooling and
ice treatment stage or system, generally designated 20, consisting of a scraped
surface heat exchanger 21 and a treatment or separator vessel 22 having a capacity
of 120 litres, which defines the ice containing treatment zone 23.
Pipe 28 connects the fermentor or green beer storage tank (both not
shown) to scraped surface heat exchanger 21, circulating pump 30 being arranged
in the pipe 24 to provide for transfer of the beer. Heat exchanger 21 is provided
with cooling system 26. Pipe 34 connects the heat exchanger 21 directly to vessel
22 and it constitutes the inlet for the cooled green beer. Vessel 21 is provided
with a stirrer or agitator 28 which is adapted to be driven by motor 29 and a separator
or filter member 30 which surrounds the outlet 31 leading to pipe 44, which leads
to the aging tank (now shown). Separator 30 is extremely important in that is must
ensure that the larger crystals forming the stable volume of ice are prevented
from leaving the treatment zone while, at the same time, must allow passage of
a small number of smaller crystals which may not melt during processing as do
the majority, but do so thereafter. Further it must be designed and/or otherwise
adapted for example, being provided with scrapers, to prevent it being clogged
by the smaller particles.
A process in accordance with the present invention was carried out
in the production of a rapidly chilled lager beer. The haze characteristics of
this, and a conventional lager beer are set out in the following table. Note that
the rapidly chill lager beer was aged for seven days, and the conventional lager
was aged for fourteen days. Also note, that the rapidly chilled lager had a significantly
higher alcohol and extract content that did the conventional lager - both of these
things would normally predispose the rapid chilled beer towards a manifestly greater
amount of haze instability, which was not found to occur.
One-Week Forcing Test:
The units of measure are "haze units" and the beers were tested in accordance with
the following procedure:
Rapidly Chilled Lager
This analysis is performed in order to predict the total suspended
chill haze stability of the product. The test is based on the accepted belief
that beer that is stored at an elevated temperature for a relatively short time,
will develope a total suspended chill haze that is very similar to that formed
in the same beer after prolonged storage at normal room temperature. Beer in a
bottle or can, is placed in an upright position in a hot water bath at 49 degrees
C, and held for a full week (seven days). Once this incubation is complete, the
beer is allowed to cool to room temperature, then passed to a cold water bath
at zero degrees C, and held for 24 hours. The bottles are removed from the cold
water bath, and inverted to suspend all of the sediment. The haze is then measured
nephelometrically with a Radiometer Hazemeter that has been calibrated against
empirical turbidity standards. The beer is poured into the instrument chamber,
and the diaphragm dial is read. This is converted to FTU's (formazin turbidity
units) by multiplying by standardized calibration factors, in known manner.
Two Month Chill Haze:
This test is performed by storing the packaged beer for two months
at room temperature. The total suspended solids are then measured from samples,
in the same way that was described under the One-Week Forcing test.
The results show that the process according to the present invention
permits a 50% reduction in aging time, without increasing haze instability. Moreover,
notwithstanding expectations predicated on the greater alcohol and extract content
of the rapidly chilled lager, the measured haze for the rapid chilled lager was
the same as the haze that developed in the conventional lager. This is considered
to be very significant, particularly since beer is now typical brewed in very
large volumes, and can sit for a protracted period before ultimately being consumed.
Turning to FIG 3, this is a flow sheet of a commercial scale facility
which may be used to process beer, and again green beer is used as the example,
according to the present invention. The facility has a green beer inlet pipe 40
connecting a fermentor or green beer surge/storage tank (not shown) to a beer cooler
42 which in turn is connected via pipe 44 to a Westfalia beer centrifuge 46. This
centrifuge is maintained at optimum efficiency to ensure that for all practical
purposes, virtually all yeast cells from the fermentation stage are eliminated
from the green beer. The centrifuge 46 is connected through pipe 48, flow meter
51, valves 52, 54, 56 and 58 and pipe 60 to beer cooler 62, the latter being connected
to heat exchange manifold 64 by pipes 57, valves 50, 68 and 70 and pipe 72. Alternatively,
centrifuge 46 can be connected directly to manifold 64 by pipe 48, through valves
52 and 70 and pipe 72. The manifold 64 serves scraped surface heat exchangers 74.
Three heat exchangers are shown arranged in parallel but, obviously, the number
or type of the heat exchangers may vary depending on requirements. A second manifold
76 is arranged to combine all material exiting the heat exchangers 74 and deliver
same via pipe 78 to treatment or separator vessel 80 which encloses treatment zone
82 having a volume of 90 hectoliters. Vessel 80 is fully insulated and is provided
with an agitator mechanism (not shown) driven by motor 84, and an exit pipe 66
which, via valves 88 and 90, connects to pipe 92 which, via valve 94 and pipe
96 connects 72 to aging tank 98. Tank 98 is provided with beer outlet pipe 100.
Vessel 80 is also provided with ice monitors or sensors 81 which identify changes
from the desired "steady state" operating condition (for example by measuring changes
in electrical conductivity of the slurry) as to ice crystal content and automatically
instruct the heat exchangers to provide more, or less, cooling to return the treatment
zone to its operating steady state condition. In the illustrated embodiment, these
monitors are conductivity probes (sensors 81) are (Yokogawa, type s250113E, NW
25, 4-20mA), which measure variations in the conductivity of the beer slurry that
are proportional to the ice concentration in the reactor. Feedback from the probes
is passed to an ammonia (the refrigerant) backpressure control valve system. Control
of the refrigerant backpressure provides control over the refrigerant temperature
and thereby also affords control over the amount of ice that is retained in the
recrystallizer. In accordance with preferred practice for the illustrated apparatus,
the probe-effected operation of the ammonia back-pressure control valve adjusts
the refrigerant temperature set point at pre-determined intervals during operation.
Typically, the system response is limited to allow the temperature set point to
be changed by no more than 0.5 degrees C every half hour, to a maximum change
of plus or minus two degrees C.
If it deviates from the set conditions vessel 80 is also provided
with a separator device (not shown in Figure 3) which prevents all but a small
number if any residual small ice crystals from exiting the vessel thereby maintaining
the "fluidized bed" feature as the ice slurry is agitated.
This equipment was obtained from Niro Process Technology B.V. , De
Beverspijken 7, 5221 EE's-Hertogenbosch, The Netherlands. The recrystalizer that
was used is part of a Niro type NFC - 60 slush freezing unit, adapted to operate
at a rated flow of about 350 hL/hr, with an inlet alcohol concentration of 7.5%
v/v, an inlet temperature of -1 degrees C, and an outlet temperature of -3.5 degrees
C, using a 20% (18hL) resident volume of supercritical ice crystals.
In operation, green beer alcohol content 7% by volume is obtained
from a regular fermentation at a temperature of about 15ºC and
is introduced into the system through pipe 40, passed through beer cooler 42 leaving
at a temperature of 8ºC to 10ºC. It is then passed
through a dropping cooler 55 which further reduces its temperature even further
to -1.5ºC thereby reducing the load on the scraped heat exchanger
74 through which the beer is subsequently passed. The temperature of the green
beer exiting heat exchangers 74 is about -4ºC and it comprises
about 2% by volume of small crystals having an average size of between 0.1 and
10 microns. The residence time of green beer in the heat exchangers is only about
one second and is then introduced immediately through manifold 78 into ice treatment
zone 80. Initially, this zone does not contain the required loading of ice slurry
and hence this was generated over a two hour start-up period when about 1,800
kilograms of larger ice crystals having an average size of 200 to 3,000 microns
were created. Vigorous agitation maintains the slurry in a homogenous mass which
is retained in the vessel by the separator while cooled green beer was treated
continuously at the rate of 450 hectoliters per hour, this equating to an average
beer residence time of about 12 minutes. The temperature in the treatment zone
is maintained at about -4ºC. The amount of ice crystals in the
zone, or "fluidized bed" remained substantially constant. The bed may be maintained
for extended periods but, from a practical viewpoint, it is removed and discarded
at end of a brewing cycle which is generally following its being used in the treatment
of from 1,200 to 15,000 hectoliters of green beer.
The amount of water exiting the system as ice is in fact not directly
measurable, although indirect inferences suggest that only 0.1% to at most 1.5%
and consequently the concentration of the beer remains essentially constant, especially
when the system is flushed with brewing water at the end of the cycle.
In summary, the process of the present invention provides a simple
to operate continuous process, a balanced beer which is less harsh, more mellow
and has greatly increased shelf life due to increased physical stability compared
with regular beers, this latter quality itself providing significant economic benefit
in greatly reducing the time required for regular aging and possibly the capital
cost involved in providing the generally required ageing tanks.
The following examples are intended to illustrate the contemplated
application of the present process to the manufacture of distilled beverages.
Distilled Alcoholic Beverages Example: Yeast action is limited by
the amount of alcohol present, and at about the level of 18% by volume, yeasts
cease to ferment. For this reason, simple fermentation cannot yield alcohol concentrations
exceeding about 18%. For higher levels, distillation is required. Note that alcohol
has a boiling point of about 78.5 degrees C., the alcohol-water azeotrope has
a boiling point of 78.3 degrees C., and water has a boiling point of 100 degrees
C.. This means that lower boiling point fractionation can enrich the alcohol content
to about as much as 96% alcohol, although in typical beverage distillation 40
to 50% alcohol is the norm. Although freeze concentration of these products has
been offered as an alternative to conventional distillation processes, economics
do not generally favor changing over from the more traditional stills. Moreover,
there is evidence that the freeze concentration process can yield a non-traditional
flavour profile, which could effect market acceptance. Accordingly, the use of
conventional boiling stills continues to be the method of choice for the manufacture
of distilled beverages.
Distilled alcoholic beverages may be divided into three major classes.
The first such class includes those starting from a starchy substrate and needing
enzymes, usually in the form of barley malt, to convert the starch to fermentable
sugars (eg, scotch from all malt; rye from mixtures of rye and malt; bourbon from
mixtures of corn, rye and malt; Irish whisky from rye, wheat and malt; and arrak,
Typically, about 15% of high diastase malt is added to the other
starch sources, water is added, and the combined mash is converted at about 56
degrees C. under agitation. The mash is then heated briefly to 62 degrees C. after
which it is cooled to about 17 to 23 degrees C. and acidified with lactic or sulphuric
acid, to a pH of 4.7 to 5. As an alternative, the pH may be lowered by microbiological
action (eg through the addition of Lactobacillus delbruckii). The lower pH controls
the contamination and favors yeast metabolic activity. Fermentation typically
takes about 3 days, and temperature is controlled at about or below 32 degrees
C.. In some distilleries, this is carried out as part of a continuous fermentation
At the end of the fermentation, the alcohol and aroma substances
are distilled off. Different whiskies are distilled to different final proofs and
then are diluted to the selected final product concentration. The type of distillation
equipment and the final proof to which a whisky is distilled determine very much
the character of the final product. Bourbon, for instance, is usually distilled
to give a 170 proof distillate, whereas with rye in a simple pot still a final
130 to 140 proof distillate is produced.
For Scotch whiskies, the typical smoky flavour is produced at least
partially from malt which has been kilned at a high temperature over a peat fire.
Scotch is aged usually in sherry or partially carbonized wooden casks. Most american
whiskies are stored in oak casks. Several of the typical flavour substance such
as guaiacol are leached out from the wood. The Scotch highland whiskies are produced
in simple pot stills, while lowland whiskies are produced in patent stills and
the malts are less heavily smoked.
The second broad classification includes those products that are
started directly from a sugar substrate, and in which at least some portion of
the native aromatics are distilled to become part of the distillate, (eg. cognac
armagnac or brandy from grapes; kirschwasser from cherrys; slivovitz and slow
gin from plums; tequila from agaves; rum from sugar cane; applejack or calvados
from apples; toddy from coconut milk; and framboise from raspberrys). The third
group includes those which are produced by adding flavour substances to quite pure
ethanol which has been obtained by distillation and rectification, (including
both liquors and liqueurs and cordials: aquavit, pernod or kummel from caraway;
or gin from juniper berries; and creme de menthe from mint and sugar; creme de
cocoa from cocoa beans, sugar and vanilla; cherry brandy from cherrys and sugar;
coffee liquor from coffee and sugar; grand marnier from orangepeel and sugar,
drambuie from honey and whisky; or, chartreuse or benedictine from herbs and sugar).
In the production of cider, juice (either pressed from crushed apples
or prepared from concentrate, is treated with an amount of sulphate necessary to
kill any indigenous microflora. Then the juice is pitched with a selected fermentation
yeast, and fermented to completion, The cider is then racked off the yeast lees.
In accordance with the practice contemplated pursuant to an application of the
present invention, the cider is the subjected to the present chill treatment.
Blending, addition of antioxidants and sweeteners, carbonation, sterilization
or aseptic packaging occurs in due course, to produce the final fermented cider
Regardless of which class of product is being considered for treatment,
the process according to the present invention may be applied to distilled beverages
following the complete conversion of the fermentable substrate to ethanol. Typically,
the distillation process will also have been completed. In the "third" above mentioned
group, it may be preferable to carry out the process of the present invention prior
to the introduction of the additional flavors). In any case, the aqueous ethanol-containing
solution is subjected to a cold stage comprising rapidly cooling the solution to
a temperature at about its freezing point ( which depending primarily on the alcohol
content varies greatly to form only minimal amounts of nascent ice crystals therein.
The resulting cooled aqueous ethanol-containing solution is then mixed for a short
period of time with a post-cold-stage resident volume of stable ice-crystals in
an aqueous ethanol-containing slurry, without any appreciable increase in ice
crystal mass contained in the resulting mixture during that mixing. Thereafter,
the so treated solution is extracted from the mixture, without any substantial
collateral increase in total dissolved solids concentration.
Figures 4 is illustrative of various freezing point temperatures
for a variety of products, as a function of dissolved solids concentrations. Note
that the present invention relates generally to fermented liquid beverages
especially fermented alcoholic beverage - for example cider, various liquors
derived whether in whole or in part through a fermentation step, and including
too fermented cereal beverages, eg. fermented malt beverages
as malt whiskey for example, but in particular, including fermented malt brewery
beverages, such as "beer" (eg lager, ale, porter, malt liquor, stout, or the
like in keeping with the most general usage of that term - and including for greater
certainty, but without limitation, "low-alcohol" and "non-alcoholic" (including
cold-contact fermented) beer).
Also, as will be appreciated, it is preferred that the chilling process
is carried out in two distinct zones and, indeed, those zones are preferable contained
in separate and discrete vessels. However, this is not essential in that the zones
may be contained within one vessel provided that the beverage is first chilled
and the nascent ice crystals formed therein and that the chilled beverage is then
mixed with the stable ice crystal containing slurry.