DE2263059C3 - Process for concentrating liquids - Google Patents

Description

IS

The invention relates to a method for concentrating liquids such as coffee-t-extract, tea, beer or citrus juices.

It is known liquid coffee extract of freezer concentration to subdue, obtaining a slurry of ice and liquid. the Slurry is fed into a centrifuge where the concentrated liquid is separated from the ice. A particular difficulty here is the foam formation in the centrifuge. To remove the Foam may even require the plant to be shut down. The foam usually contains valuable coffee solids.

In US-PS 3102 036 a method for Freeze-concentrating is described in which heat-sensitive solutions such as coffee extract are used for freeze-concentrating and centrifugation under an inert gas to prevent foaming.

In addition, one has already centrifuged under pressure for the same purpose.

It has now been found, surprisingly, that this treatment is not required, but rather the Once formed foam is only removed, destroyed and the resulting solution in the cycle can be returned without significant organoleptic changes occurring in the end product. Such a practice was not foreseeable.

The invention thus relates to a method for concentrating liquids, such as coffee extract, Tea, beer or citrus juice, by freeze-concentrating the liquid, feeding the obtained Put the slurry of ice and concentrated liquid in a centrifuge and separate the concentrated liquid from ice, which is characterized by the fact that it is placed in the centrifuge separates accumulating foam, if necessary liquefied by the application of heat and / or steam and this liquid is returned to the starting solution.

The foam from the centrifuge can be removed with the wash water used to wash the ice and fed to a secondary feed liquid reservoir. This container contains liquid that is fed into a crystallizer or other freezer. From here from the liquid is fed back into the centrifuge, and the foam from the storage container is fed into a treatment tank, in which the foam either by prolonged storage, e.g. B. 2 up to 24 hours and usually 8 to 16 hours, or converted to liquid by treatment with steam will. The liquid is then returned to a primary storage tank containing fresh feed liquid, z. B. from coffee extractors, and from which the mixture in the secondary Reservoir is fed. This storage container katin in front of or behind a filter or solid bowl centrifuge be arranged to remove wax or other deposits.

It was to be assumed that the foam either by standing for a long time or by treating it liquid formed with steam would have an undesirable aroma. However, it was surprising found that when this liquid is mixed with the feed liquid, the treatment in the freeze concentrator and then converting the mixture into a powder or Granulate a high quality, soluble coffee with an excellent taste is obtained.

The foam can also leave the freeze-concentrating centrifuge with the mother liquor. This mixture can then be fed into a storage container, from which the foam is treated in the same way and in Liquid can be transferred. This liquid is returned and filled with freshly supplied, mixed with liquid coffee extract.

The ice from the centrifuge can be fed into a melting container with foam. The temperature the capacity of the container is increased so much that the foam is converted into liquid, this conversion occurs so rapidly that no accumulation of foam occurs. For this purpose, the temperature of the Container contents can be increased to 26.7 to 65.6 ° C, preferably to 32.2 to 43.3 ° C. The temperature rise may be by steam coils, electrically heated heating coils, or in any other suitable manner be effected.

Part of the foam or all of the foam with the mother liquor can also with the mother liquor are mixed to obtain a foam mass which is frozen and freeze-dried.

The examples illustrate the invention. The examples refer to FIG. 1 to 3 referred to.

example 1

In Fig. 1 the invention is shown in application to a single-stage concentration system. 10 and 11 are two primary storage containers. In the storage container 10 is derived from coffee extractors at 12 Feed liquid fed. The liquid from the reservoir 10 can be at a low Temperature, e.g., from -1.67 to 1.67 ° C, thereby causing the precipitation of waxes and the like separating material is promoted. The deposited precipitate is by means of a filter or Solid bowl centrifuge 13 removed before feeding into the storage container 11. The liquid from the Storage container U is fed into a secondary storage container 17 by means of a pump 16. The liquid From the storage container 17 is fed into a crystallizer 20 by means of a pump 18. Of the Crystallizer 20 represents the first part and centrifuge 21 the second part of a freeze concentrating device In the crystallizer 20, ice is formed in the liquid. The resulting ice-liquid slurry is fed into the centrifuge 21. The centrifuge 21 can be a known centrifuge with rotating Be a sieve basket from which the ice is continuously scraped off. The ice is through line 22 in a

Melt container 23 fed. Part of the liquid from the container 23 is used as waste water by a Line 24 discharged; Another part of the liquid is by means of a pump 27 through a line 28 in the Centrifuge 21 is pumped and serves as Wascl.wasser for washing the ice, removing coffee solids from the ice removed. The washing water is fed together with foam from the centrifuge 21 through a line 30 in a secondary reservoir 17 is fed. The mother liquor that passes through the screen basket is fed via a line 31 into a mother liquor container 32.

The ode by appropriate drain channels ^r grooves 34 and 35 from the reservoir 17 and the mother liquor tank 32 overflowed foam is fed into a tank 36, maintained in the some hours, the foam and is treated or or with steam, whereby it is converted into liquid. This liquid is then fed into one or both of the storage containers 0 and 11 by means of a pump 40.

A part of the liquid can by means of a pump 41 from the outlet of the crystallizer 20 to its inlet to be led back.

B e i s ρ i e I 2

In Fig. 2 the invention is shown applied to a two-stage concentration system! That two-stage system is similar to that in FIG. 1 illustrated system; the liquid from the container However, 32 is pumped into a second crystallizer 50. The one obtained from this crystallizer Slurry is fed to a second centrifuge 51. The ice from the centrifuge 51 is over a Line 52 is fed into a container 17. The mother liquor from the centrifuge 51 is via a Line 54 is fed into a product container 55. The ice from the centrifuge 21 is in a melting vessel 56 is fed. The washing water from the centrifuge 21 is in a washing water tank 57 is fed. The overflowing foam that comes from one or all of them Containers 32, 57, 17 and 55 can originate, is fed into the container 36, from where the out of the foam resulting liquid is pumped back into one or both reservoirs 10 and 11.

Example 3

3 shows a centrifuge 60 into which a slurry of ice and coffee liquid originating from a crystallizer is fed at 61. The centrifuge 60 may have a rotating screen basket from which the ice is scraped and fed into an outlet conduit or chute 62. The mother liquor exits the centrifuge 60 at 63 and the wash water exits at 64. The ice is fed together with the foam into a container 66, which is heated to about 37.8 ° C. with a heating device 67. The foam is converted into liquid and partly discharged as waste water at 69 (or returned to the coffee extractors), partly through a pump 70 and line 71 at 72 into the centrifuge as washing water for the centrifuge basket and partly at 73 for washing the ice fed into this in the centrifuge. The washing water can be cooled if necessary.

The application of the present invention also includes that in British patent applications 11 96 601, 1196 602, 1199 914, 1178 775, 1178 774, 1178 772, 11 72 836, 11 72 838, 11 72 832 and 11 72 835 Suggestions and inventions.

For this purpose 3 sheets of drawings

Claims (1)

Claim: Process for concentrating liquids, such as coffee extract, tea, beer or citrus fruit juices, by freeze-concentrating the liquid, feeding the resulting slurry of ice and concentrated liquid into a centrifuge and separating the concentrated liquid from the ice, characterized in that _{) 0} separates the foam produced in the centrifuge, if necessary liquefied by using heat and / or steam, and this liquid is returned to the starting solution.