FREEZE CONCENTRATION

CONCENTRATION PAR LYOPHILISATION

English Abstract

Abstract of the Disclosure
The invention includes a method and
apparatus for the concentration of a liquid
comprising coffee extract, tea, beer or citrus
fruit wherein the liquid is subjected to freeze
concentration to form ice in the liquid, the liquid
and ice are fed to a centrifuge which separates the
concentrated liquor from the ice but produces also
a foam, the foam is separated from the ice and
liquid and further treated so as to be included
in the final concentrated product.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for the concentration of a liquid comprising coffee
extract, tea, beer or citrus fruit wherein the liquid is subjected to freeze
concentration to form ice in the liquid, the liquid and ice are fed to a
centrifuge which separates the concentrated liquor from the ice but produces
also a foam, the foam is separated from the ice and liquid, further treated
to cause it to subside to a liquid condition, and included in the final
concentrated product.


2. A method for the concentration of a liquid comprising coffee
extract, tea, beer or citrus fruit juice wherein the liquid is subjected to
freeze concentration to form ice in the liquid, the liquid and ice are fed to
a centrifuge which separates the concentrated liquor from the ice, but
produces also a foam, the foam is treated to reduce it to a reformed liquid
and the reformed liquid is combined with infeed liquid which is to be sub-
jected to said freeze concentration.


3. A method as claimed in claim 1 comprising feeding liquid from a
primary holding tank to a secondary holding tank, feeding liquid from the
secondary holding tank to a freeze concentrating apparatus and thence to a
centrifuge, washing the ice in the centrifuge with wash water, feeding the
wash water and foam to the secondary holding tank, feeding the foam from the
holding tank to a foam treatment tank, treating the foam in said foam treat-
ment tank to reform liquid from the foam and feeding the reformed liquid to
said primary holding tank.



4. A method as claimed in claim 1 or 2 comprising feeding mother liquid
with some foam from the centrifuge to a mother liquid holding tank, removing
the foam from the latter tank, treating this foam to reform it to a liquid and
feeding the latter to the liquid supplied to be freeze concentrated.


5. A method as claimed in claim 1, 2 or 3 wherein liquid from a first
freeze concentration and centrifuging step is subjected to a second freeze
contentration and centrifuging step, and foam from the second centrifuging
step is reformed to liquid which is fed into the liquid being fed to the first
concentration step.


6. A method as claimed in claim 1 wherein foam is mixed with mother
liquid to produce a foamed mass which is frozen and subjected to freeze drying.


7. A method as claimed in claim 1 wherein the foam is treated in a tank
by subjecting it to temperature sufficiently high to cause the foam to reform
to a liquid.


8. A method as claimed in claim 7 wherein the temperature is 80-150°F.


9. A method as claimed in claim 7 wherein the temperature is 90-110°F.


10. Apparatus for the concentration of liquid comprising a crystallizer,
means for supplying liquid to the crystallizer, a centrifuge, means for feeding
liquid with ice from the crystallizer to the centrifuge, a foam treatment tank
means for feeding froth from the centrifuge to the foam treatment tank, means
for conveying liquid from the treatment tank to the liquid in the apparatus.



11. Apparatus as claimed in claim 10 having a holding tank receiving
froth from the centrifuge and means for conveying froth overflowing from the
holding tank to the treatment tank.


12. Apparatus as claimed in claim 10, having two holding tanks, one
being a mother liquid tank connected to the mother liquor outlet of the
centrifuge and the other being connected to a wash water and froth



exit of the centrifuge, means being provided for conveying froth overflowing
from both tanks to the liquid supplied to the crystallizer.


13. Apparatus as claimed in claims 10, 11 or 12 having two primary
holding tanks for liquid to be supplied to the crystallizer, means connecting
one primary holding tank to the other through a filter or centrifuge, and a
pump connected between the froth treatment tank and one or both of the primary
tanks.


14. Apparatus as claimed in claim 10 having a second crystallizer the
output of which is connected to a second centrifuge, a first holding tank,
means for supplying liquid to be treated to the holding tank, means for feeding
ice from the second centrifuge to the holding tank, means for feeding liquid
from the holding tank to the first crystallizer, a second holding tank, means
for feeding liquid and foam from the first centrifuge to the second holding
tank, means for conveying froth overflowing from the first and second holding
tanks to the froth treatment tank.


15. Apparatus as claimed in claim 14 having a third holding tank, the
second and third holding tanks being connected to the first centrifuge to
receive respectively mother liquor and ice-wash water therefrom, the means for
conveying froth being arranged to convey the froth overflowing from both
second and third holding tanks to the froth treatment tank.


16. Apparatus as claimed in claim 14 or 15 having two primary holding
tanks for liquid to be fed to the first cyrstallizer, means for connecting
these two primary tanks together through a sediment separation device, the
froth treatment tank being connected to one or both of the primary tanks,
while the primary tank that receives liquid from the separation device is
connected to said first holding tank.


17. Apparatus as claimed in any of claims 10, 11 or 14 wherein the froth
treatment tank contains a heating device in the lower part thereof.


18. Apparatus as claimed in claim 10 wherein the foam treatment tank is



connected to the centrifuge to receive ice and foam therefrom and is separa-
tely connected to the centrifuge to supply liquid as wash water from the
centrifuge basket and/or as ice-wash water.

Description

1045443
This invention relates to the concentration of liquid coffee extract,
tea, beer and citrus fruit juices.
It is known to subject liquid coffee extract to freeze concentrations
whereby a slurry of ice and liquid is produced wiich is fed to a centrifuge
which separates the concentrated liquor from the ice. A particular difficulty
is experienced due to formation of foam in the centrifuge which may even
necessitate shutting down the plant while the foam is removed. The foam
usually contains useful coffee solids.
The present invention provides a method for the concentration of
a liquid comprising coffee extract, tea, beer or citrus fruit wherein the liquid
is subjected to freeze concentration to form ice in the liquid, the liquid
and ice are fed to a centrifuge which separates the concentrated liquor from
the ice but produces also a foam, the foam is separated from the ice and liquid,
further treated to cause it to subside to a liquid condition, and included in
the final concentrated product.
The foam may be combined with infeed liquid which is fed to the
freeze concentration apparatus.
The foam from the centrifuge may be taken out with the wash water
used for washing the ice and fed to a secondary feed liquid holding tank which
contains liquor which is fed to a crystallizer or other freezing apparatus
whence it is again fed to the centrifuge, the foam from the holding tank
being fed to a treatment vessel in which the foam is caused to subside to
liquid either by a long holding period e.g. 2 to 24 hours (usually 8 to 16
hours) or by being treated with steam, the liquid being then fed back to a
primary holding tank which receives fresh feed liquid e.g. from coffee ex-
tractors and feeds the mixture to the secondary holding tank. This holding
D

~045443 ~

tank may be arranged before or after a filter or ~
bowl type centrifuge for removing wax or other ¦
precip;tates, ,~
It was to be expected that the liquid
produced from foam either by long standing or by
steam treatment would have an undesirable flavour i
but we have found that this liquid mixed with the
feed liquor and treated in the freeze concentration
system and subsequently reduced to powder or granular ,
form provides a soluble coffee of high quality and 1
very acceptable taste. Il
Foam may also leave the freeze concentration ~¦
centrifuge with the mother liquor and this may be fed
to a holding tank from which foam may likewise be
treated to reduce it to liquid which is fed back to
mix with incoming fresh coffee liquid.
The ice from the centrifuge may be fed to
a melting tank with foam and the temperature of the
contents of the tank increased to an-extent causing the
foam to subside into liquid sufficiently rapidly that
there is no build up of foam, Thus the temperature
of the contents of the tank may be raised to 80-150F
e.g. 90 - 110F~ This may be effected with steam
coils or an electrically heated coil or in any other
suitable way~
Alternatively some or all of the foam with


-2-

1~4S443
the mother liquor may be mixed with the mother liquor to produce a foamed mass
which is frozen and subjected to freeze drying.
From another aspect, the invention provides apparatus for the con-
centration of liquid comprising a crystallizer, means for supplying liquid
to the crystallizer, a centrifuge, means for feeding liquid with ice from the
crystallizer to the centrifuge, a foam treatment tank means for feeding froth
from the centrifuge to the foam treatment tank, means for conveying liquid
from the treatment tank to the liquid in the apparatus.
The invention will be further described by way of example with
reference to the accompanying diagrammatic drawings wherein:
Figure 1 shows the invention applied to a single stage concentration
system; and
Figure 2 shows the invention applied to a double stage concentration.
Figure 3 shows a centrifuge system used in a modification of the
invention.
In Figure 1 two primary holding tanks 10, 11 are shown. The tank
10 is fed with feed liquor at 12 coming from coffee extractors. The liquid
from tank 10 may at a low temperature e.g. 29 - 35 F to assist in precipitating
waxes and like precipitating material which is removed by a filter or bowl
type centrifuge 13 before being fed to the tank 11. The liquor from tank 11
is fed by pump 16 into a secondary holding tank 17. Liquor from tank 17 is
fed by pump 18 into a crystallizer 20 comprising the first part of a freeze
concentrating system, the otherpart of which is a centrifuge 21. The
crystallizer 20 causes ice to form in the liquor and the resultant slurry of
ice and liquor enters the centrifuge 21. The centrifuge 21 may be the known
type having a rotating perforated basket from which the ice is scraped con-
tinuously. The ice leaves at 22 and enters a melting tank 23. Some liquid
from 23 goes to waste at 24 while some is pumped by pump 27 through pipe 28
to the centrifuge 21 to serve as

104~443

wash water which oa~hoc the ice to remove coffee solids ,j
from the ice. The wash water passes out with foam at ¦
30 and is fed to the secondary holding tank 17. The
mother li~uor which passes through the perforated basket
is fed by pipe 31 to a mother liquor tank 32, Foam
from tanks 17, 32 overflows through suitable channels
or chutes 34, 35 and is fed to a vessel 36 in which the
foam is held for some hours and/or treated with steam to
cause it to subside to liquid.~ This liquid is then fed
by pump 40 and pipe ~ to one or both of the tanks 10,11. .
Some liquid may be recycled by pump 41 from
the outlet of crystallizer 20 to its inlet.
The double sl:age system shown in Figure 2 is -
.. ' ' ' jl
similar but li~uor from the tank 32 is pumped to a second 1,
crystallizer 50 and the slurry from this crystallizer is
fed to a second centrifuge 51, The ice from 51 is fed ¦
through line 52 to the feed tank 17, Mother liquor from
51 is fed by pipe 54 to a product tank 55, The ice from
the centrifuge 21 goes via-pipe 22 to a melting tank 56 .
and the wash water goes through pipe 30 to a wash water
tank 57. Foam may overflow from any or all of the tanks
32, 57, 17, 55 and be fed to the treatment tank 36 whence
the l~quid from the foam is pumped back to one or both
of the tanks 10, 11.
Figure 3 shows a centrifuge 60 fed at 61 with
a slurry of ice and coffee liquor from a crysta;lizer,
The centrifuge may be of the kind having a rotating
perforated basket from which the ice is scraped off and


lV45443
fed to an outlet pipe or chute 62. Mother liquor leaves at 63
and wash water at 64. The ice together with foam enters a tank
16 which is heated by a heater 67 up to say 100F. The foam
is reduced to liquid and passes partly to waste at 69 (or back
to the coffee extractors) and partly by pump 70 and pipe 71 to
enter the centrifuge 72 to serve as wash water for the centrifuge
basket and partly at 73 to wash the ice in the centrifuge. The
wash water may be cooled if required.