CA1110105A - Low beverage soluble iron content filter aid and method for its production - Google Patents
Low beverage soluble iron content filter aid and method for its productionInfo
- Publication number
- CA1110105A CA1110105A CA315,206A CA315206A CA1110105A CA 1110105 A CA1110105 A CA 1110105A CA 315206 A CA315206 A CA 315206A CA 1110105 A CA1110105 A CA 1110105A
- Authority
- CA
- Canada
- Prior art keywords
- acid
- diatomite
- filter aid
- beverage
- soluble iron
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
Abstract A low beverage soluble iron content filter aid, especially diatomite, is disclosed, as is the method for its production, which comprises contacting the granular filter aid with tannic acid, gallic acid, or mixtures thereof, preferable in aqueous solution. Color control agents such as citric acid may also be present in the solution. The treated filter diatomite is useful in the filtration of vegetable based beverages, especially beer, wine, ale and fruit juices. The invention is also applicable to other filter aids which contain beverage soluble iron, such as perlite.
Description
LOW BEVERAGE SOLUBLE IRON CONTENT
_ILTER AID AN~ METHOD FOR ITS PRODUCTION
Background of the Inventior, The invention herein relates to filter aids, especially diatomite, having a low soluble iron content. It also relates to a method for production of such low soluble iron filter aid.
In the manufacture or processing of a number of vegetable based beverages (notably beer, ale, wine and fruit juices) the beverage is filtered one or more times through granular heterogeneous filter media, usually diatomite. These filter media contain small lo amounts of various minerals and compounds, among which are iron compounds. A certain small portion of the iron content of the media is soluble in the vegetable beverages. This portion of the iron may be referred to as "beverage soluble iron" (often abbreviated "BSI").
The presence of higher levels of BSI dissolved in the beverage can be deleterious to the taste and long term stability ("shelf life") of the beverage. Consequently, it would be desirable to have a filter medium which is low in BSI content but which retains its desirable filtration and clarification properties.
Brief Summary of the Invention The invention hereln is a method for the production of low beverage soluble iron content filter aid, especially diatomite, which comprises contacting granular filter aid containing an initial content of beverage soluble iron with an aqueous solution of tannic acid, gallic acid or mixtures thereof to reduce that beverage soluble iron content. Color control agents such as citric acid may also be present in the solution. Also a part of the present invention is a filter aid low in beverage soluble iron content produced in accordance with this method.
`~~ ~ .
Detailed Description and Preferred Embodiments The basic material used in the process of the invention is a granular filter aid which initially contains bevera~e soluble iron. ("Initially" herein refers to the BSI content immediately prior to the treating process of this invention. The filter aid by that time will probably have already undergone prior processing which may have altered the BSI content of the original material such as crude ore froM which the filter aid is made.) For con-venience, the invention herein will be discussed in terms oF
diatomite, since this is the common and preferred filter aid ~or -~
vegetable beverages. However, it will be understood that the -;~
process is also applicable to other filter aids, such as perlite and clays, which contain beverage soluble iron. The considerations discussed below for diatomite will be similarly applicable to these other filter aids.
Diatomite is a naturally occurring material found in deposits in various parts of the world. It is formed by the deposition over many years of the si1iceous skeletons oF ancient microscopic marine organisms known as diatoms. Commercial deposits are found in California, Oregon, Washington and several other states, as well as in several Foreign countries. The chemical composition oF a typical diatomite is 85 to 30% silica, 2 to 4%
alumina, l to 2% ferric oxide, and small amounts (less than 1%) of materials such as magnesia, lime, alkalies and titania. There are also typically up to about 5% volatile materials including water, carbon dioxide and organics.
After being minedg the diatomite (which is also frequently known as "diatomaceous earth") may be crushed, screeneds calcined and classified to separate it into a variety oF gracles of dif-ferent granular sizes, purities and reactivities. The grade o-F diatomite S
1 and the various conventional steps of handling and processing are not particularly critical to the present invention. The presence of beverage so'iuble iron is in part a function of the chemical composition of the original ore. The type of conventional (largely mechanical and thermal) processing techniques used to produce the commercial grades of diatomite may eFfect the overall amount of BSI
in the final diatomite product. ~lowever, this invention is generally applicable to all varieties of diatomite containing significant quantities of beverage soluble iron.
In the process of the present invention the beverage soluble iron content of the diatomite is reduced by contacting the granulated diatomite with an aqueous solution of tannic acid, gallic acid or mixtures oF these acids. Tannic acid (also known as gallotannic acid and tannin), is a natura'lly occurring substance Found wide'ly in plants, particularly oak and sumac. The exact molecular formula is unknown but is believed to be a mixture of a number of gallic acid derivatives. A typical pub'lished formula is C76H52046 with a molecular structure of ~1~20R
~ - o~OR
P~O~
oR
wherein R is galloyl, m-digalloyl, or m-trigalloyl substituents.
Typical commercial physical properties of tannic acid are that it decomposes at about 210C; may be in the form of powder, flakes or a spongy mass; is odorless; has a strong astringent taste3 and is soluble in water, alcohol and acetone and almost insoluble in i benzene, chloroform and ether.
~ ;
.
. ~ . . .. . . . . .
l Gallic acid (3,~,5-trihydroxybenzoic acid) is commonly in the form of colorless or slightly yellow crystalline needles or prisms which are soluble in alcohol and glycerol and sparingly soluble in water and ether. It has a specific gravity of 1.7 and a melting point of approximately 230C. It is commonly produced by the action of mold on solutions of tannin or by boiling tannin with strong acid or caustic soda.
In the present invention the diatomite is treated by contacting with aqueous solutions of tannic acid, gallic acid or mixtures of these two. The solution will normally contain 1~ to 20% acid by weight although the strength oF the acid solution is not critical. The amount of acid (measured as acid rather than solution) useful in the present process will be in the range of From 0.1 to 1.5 grn-moles of acid per ton of diatomite, preferable 0.2 to 1.2 gm-moles of acid per ton of diatomite.
Contacting may be accomplished by any o~ several means.
The acid solution may be sprayed on the diatomite while the latter is being classified by suspension in an air stream. Alternatively, the diatomite may be simply washed with the acid, as for instance being put through a bath of the acid solution, or having the acid poured through a layer of the diatomite. Other conventional liquid/solid contacting means such as fluidized beds may also be used. The particular choice of technique to contact the acid and diatomite will often be based on availab1e equipment, economics and similar criteria.
The time of contact will vary according to the strength of the acid solution and the amount of beverage soluble iron present in the diatomite (a typical analysis of diatomite shows 45 to 55 ppm of BSI). The contact time may be very short, such as merely the time it takes to form a slurry of the diatomite in the 1 solution and filter it. The optimum treating time For any specific sample of diatomite and strength of acid can be readily determined by routine experimentation.
If desired, the diatomite and/or acid solution may also be heated to a temperature on the order of 90C to 100C prior to contacting to expedite the reaction by which the acid extracts ~SI
from the diatomite. The exact nature of this extraction reaction is not known, but it is believed that the iron is extracted by being complexed with the acid.
lo Following the acid contacting the diatomite may be washed with water to remove the acid and extracted iron. If desired, a plurality of rinses may be used, the rinse water may be heated, and/or varying lengths of rinse period may be used.
However, rinsing is not mandatory, for after being treated with the acid the iron solubility in the beverages is reduced whether it remains on the diatomite or is removed by rinsing. The optimum rinse techniques, if any, will be a simple matter of choice for one -skilled in the art.
If desired, the aqueous solution of tannic and/or gallic acid may also contain color control agents. These acids have a tendency to impart dark color to solutions~ and the color control agents react with any excess acid to reduce that tendency9 thus discolorizing the solutions. Suitable color control agents include citric acid, sodium sulfite, potassium bromate, and ethylene diamine tetraacetric acid. Levels of concentration of these agents will be a matter of routine choice, but typical levels which have been found satisfactory are 0.2 to 0.3 molar in a solution which is 0.04 molar in tannic and/or gallic acid.
The following examples will illustrate the process of this invention. 50 gm samples of a flux calcined California ..
1 diatomite containing approximately 45 to 55 ppm BSI was pre-heated to approximately 200F (93C) for three hours. Aqueous solutions of acid were made up using 17% acid in water. Each sample of heated diatomite was put into a blender which was equipped with heating means for maintaining the preheat temperature. Agitation of the diatomite to form an air suspension was obtained by the blender blades. The acid was sprayed into the blender jar.
Complete dispersion of the acid through the diatomite was obtained in appro~imately 2 minutes. The diatomite was then dried and the BSI concentration determined.
In an alternative technique a filter cake was formed on a Buchner filter using 50 gm of diatomite and water. The ~ilter cake was then washed with 500 ml of 17% acid solution. The acid remained in contact with the filter cake for approximately 10 minutes.
Thereafter the filter cake was rinsed with water, dried, and BSI
concentration determined. Results were found to be equivalent to the spray technique.
Typical results are presented in the table below.
Dosage Reduction lb acid/ton diatomite of BSI, %
Tannic Acid 0.9 30 1.7 50 1.8 35 1,9 53 3.3 70 3.6 68 Gallic Acid 0.43 7 0.85 35 0.95 12 1.9 30
_ILTER AID AN~ METHOD FOR ITS PRODUCTION
Background of the Inventior, The invention herein relates to filter aids, especially diatomite, having a low soluble iron content. It also relates to a method for production of such low soluble iron filter aid.
In the manufacture or processing of a number of vegetable based beverages (notably beer, ale, wine and fruit juices) the beverage is filtered one or more times through granular heterogeneous filter media, usually diatomite. These filter media contain small lo amounts of various minerals and compounds, among which are iron compounds. A certain small portion of the iron content of the media is soluble in the vegetable beverages. This portion of the iron may be referred to as "beverage soluble iron" (often abbreviated "BSI").
The presence of higher levels of BSI dissolved in the beverage can be deleterious to the taste and long term stability ("shelf life") of the beverage. Consequently, it would be desirable to have a filter medium which is low in BSI content but which retains its desirable filtration and clarification properties.
Brief Summary of the Invention The invention hereln is a method for the production of low beverage soluble iron content filter aid, especially diatomite, which comprises contacting granular filter aid containing an initial content of beverage soluble iron with an aqueous solution of tannic acid, gallic acid or mixtures thereof to reduce that beverage soluble iron content. Color control agents such as citric acid may also be present in the solution. Also a part of the present invention is a filter aid low in beverage soluble iron content produced in accordance with this method.
`~~ ~ .
Detailed Description and Preferred Embodiments The basic material used in the process of the invention is a granular filter aid which initially contains bevera~e soluble iron. ("Initially" herein refers to the BSI content immediately prior to the treating process of this invention. The filter aid by that time will probably have already undergone prior processing which may have altered the BSI content of the original material such as crude ore froM which the filter aid is made.) For con-venience, the invention herein will be discussed in terms oF
diatomite, since this is the common and preferred filter aid ~or -~
vegetable beverages. However, it will be understood that the -;~
process is also applicable to other filter aids, such as perlite and clays, which contain beverage soluble iron. The considerations discussed below for diatomite will be similarly applicable to these other filter aids.
Diatomite is a naturally occurring material found in deposits in various parts of the world. It is formed by the deposition over many years of the si1iceous skeletons oF ancient microscopic marine organisms known as diatoms. Commercial deposits are found in California, Oregon, Washington and several other states, as well as in several Foreign countries. The chemical composition oF a typical diatomite is 85 to 30% silica, 2 to 4%
alumina, l to 2% ferric oxide, and small amounts (less than 1%) of materials such as magnesia, lime, alkalies and titania. There are also typically up to about 5% volatile materials including water, carbon dioxide and organics.
After being minedg the diatomite (which is also frequently known as "diatomaceous earth") may be crushed, screeneds calcined and classified to separate it into a variety oF gracles of dif-ferent granular sizes, purities and reactivities. The grade o-F diatomite S
1 and the various conventional steps of handling and processing are not particularly critical to the present invention. The presence of beverage so'iuble iron is in part a function of the chemical composition of the original ore. The type of conventional (largely mechanical and thermal) processing techniques used to produce the commercial grades of diatomite may eFfect the overall amount of BSI
in the final diatomite product. ~lowever, this invention is generally applicable to all varieties of diatomite containing significant quantities of beverage soluble iron.
In the process of the present invention the beverage soluble iron content of the diatomite is reduced by contacting the granulated diatomite with an aqueous solution of tannic acid, gallic acid or mixtures oF these acids. Tannic acid (also known as gallotannic acid and tannin), is a natura'lly occurring substance Found wide'ly in plants, particularly oak and sumac. The exact molecular formula is unknown but is believed to be a mixture of a number of gallic acid derivatives. A typical pub'lished formula is C76H52046 with a molecular structure of ~1~20R
~ - o~OR
P~O~
oR
wherein R is galloyl, m-digalloyl, or m-trigalloyl substituents.
Typical commercial physical properties of tannic acid are that it decomposes at about 210C; may be in the form of powder, flakes or a spongy mass; is odorless; has a strong astringent taste3 and is soluble in water, alcohol and acetone and almost insoluble in i benzene, chloroform and ether.
~ ;
.
. ~ . . .. . . . . .
l Gallic acid (3,~,5-trihydroxybenzoic acid) is commonly in the form of colorless or slightly yellow crystalline needles or prisms which are soluble in alcohol and glycerol and sparingly soluble in water and ether. It has a specific gravity of 1.7 and a melting point of approximately 230C. It is commonly produced by the action of mold on solutions of tannin or by boiling tannin with strong acid or caustic soda.
In the present invention the diatomite is treated by contacting with aqueous solutions of tannic acid, gallic acid or mixtures of these two. The solution will normally contain 1~ to 20% acid by weight although the strength oF the acid solution is not critical. The amount of acid (measured as acid rather than solution) useful in the present process will be in the range of From 0.1 to 1.5 grn-moles of acid per ton of diatomite, preferable 0.2 to 1.2 gm-moles of acid per ton of diatomite.
Contacting may be accomplished by any o~ several means.
The acid solution may be sprayed on the diatomite while the latter is being classified by suspension in an air stream. Alternatively, the diatomite may be simply washed with the acid, as for instance being put through a bath of the acid solution, or having the acid poured through a layer of the diatomite. Other conventional liquid/solid contacting means such as fluidized beds may also be used. The particular choice of technique to contact the acid and diatomite will often be based on availab1e equipment, economics and similar criteria.
The time of contact will vary according to the strength of the acid solution and the amount of beverage soluble iron present in the diatomite (a typical analysis of diatomite shows 45 to 55 ppm of BSI). The contact time may be very short, such as merely the time it takes to form a slurry of the diatomite in the 1 solution and filter it. The optimum treating time For any specific sample of diatomite and strength of acid can be readily determined by routine experimentation.
If desired, the diatomite and/or acid solution may also be heated to a temperature on the order of 90C to 100C prior to contacting to expedite the reaction by which the acid extracts ~SI
from the diatomite. The exact nature of this extraction reaction is not known, but it is believed that the iron is extracted by being complexed with the acid.
lo Following the acid contacting the diatomite may be washed with water to remove the acid and extracted iron. If desired, a plurality of rinses may be used, the rinse water may be heated, and/or varying lengths of rinse period may be used.
However, rinsing is not mandatory, for after being treated with the acid the iron solubility in the beverages is reduced whether it remains on the diatomite or is removed by rinsing. The optimum rinse techniques, if any, will be a simple matter of choice for one -skilled in the art.
If desired, the aqueous solution of tannic and/or gallic acid may also contain color control agents. These acids have a tendency to impart dark color to solutions~ and the color control agents react with any excess acid to reduce that tendency9 thus discolorizing the solutions. Suitable color control agents include citric acid, sodium sulfite, potassium bromate, and ethylene diamine tetraacetric acid. Levels of concentration of these agents will be a matter of routine choice, but typical levels which have been found satisfactory are 0.2 to 0.3 molar in a solution which is 0.04 molar in tannic and/or gallic acid.
The following examples will illustrate the process of this invention. 50 gm samples of a flux calcined California ..
1 diatomite containing approximately 45 to 55 ppm BSI was pre-heated to approximately 200F (93C) for three hours. Aqueous solutions of acid were made up using 17% acid in water. Each sample of heated diatomite was put into a blender which was equipped with heating means for maintaining the preheat temperature. Agitation of the diatomite to form an air suspension was obtained by the blender blades. The acid was sprayed into the blender jar.
Complete dispersion of the acid through the diatomite was obtained in appro~imately 2 minutes. The diatomite was then dried and the BSI concentration determined.
In an alternative technique a filter cake was formed on a Buchner filter using 50 gm of diatomite and water. The ~ilter cake was then washed with 500 ml of 17% acid solution. The acid remained in contact with the filter cake for approximately 10 minutes.
Thereafter the filter cake was rinsed with water, dried, and BSI
concentration determined. Results were found to be equivalent to the spray technique.
Typical results are presented in the table below.
Dosage Reduction lb acid/ton diatomite of BSI, %
Tannic Acid 0.9 30 1.7 50 1.8 35 1,9 53 3.3 70 3.6 68 Gallic Acid 0.43 7 0.85 35 0.95 12 1.9 30
2.9 40 It will be evident from these data that the process of the present invention significantly reduces the amount of beverage soluble iron present in diatomite filtrates. The resultant low beverage soluble iron content diatomite therefore makes a superior filtration medium for vegetable beverages for it substantially reduces the amount of iron which is extracted by the beverage from the diatomite during filtration.
Other contacting fluids were experimented with to determine if there were other materials equivalent to tannic and gallic acids. Water, starch, sucrose, monobasic sodium phosphate, tartaric acid, gluconic acid, sallcyllc acid, and the sodium salt of ethylene diamine tetraacetic acid were all tried. The organic acids in this group produced only insignificant reduction in BSI. The remaining materials were able to reduce BSI by larger amounts than the organic acids, but took long time periods ~often 10 days to 2 weeks) to reach the BSI reduction levels obtained with tannic and gallic acids in a matter of minutes.
, . .
. , . , . . ~ .
.
Other contacting fluids were experimented with to determine if there were other materials equivalent to tannic and gallic acids. Water, starch, sucrose, monobasic sodium phosphate, tartaric acid, gluconic acid, sallcyllc acid, and the sodium salt of ethylene diamine tetraacetic acid were all tried. The organic acids in this group produced only insignificant reduction in BSI. The remaining materials were able to reduce BSI by larger amounts than the organic acids, but took long time periods ~often 10 days to 2 weeks) to reach the BSI reduction levels obtained with tannic and gallic acids in a matter of minutes.
, . .
. , . , . . ~ .
.
Claims (24)
1. A method for the reduction of the beverage soluble iron content of a filter aid which comprises contacting the filter aid in granular form with tannic acid, gallic acid or mixtures thereof.
2. A method as in Claim 1 wherein said filter aid comprises diatomite.
3. A method as in Claim 2 wherein said tannic acid, gallic acid or mixture thereof is in aqueous solution.
4. A method as in Claim 3 wherein said aqueous solution has a concentration of 1% to 20% acid by weight.
5. A method as in Claim 2 wherein said contacting comprises spraying the diatomite with the acid.
6. A method as in Claim 2 wherein said contacting comprises washing the diatomite with the acid.
7. A method as in Claim 2 wherein the acid is contacted in an amount of 0.1 to 1.5 gm-moles of acid per ton of diatomite.
8. A method as in Claim 7 wherein the acid is contacted in an amount of 0.2 to 1.2 gm-moles of acid per ton of diatomite.
9. A method as in Claim 2 wherein said acid comprises tannic acid.
10. A method as in Claim 2 wherein said acid comprises gallic acid.
11. A method as in Claim 2 wherein said acid comprises a mixture of tannic acid and gallic acid.
12. A method as in Claim 3 wherein solution also con-tains a color control agent.
13. A method as in Claim 12 wherein said color control agent is citric acid, sodium sulfite, potassium bromate or ethylene diamine tetraacetic acid.
14. A filter aid which has had its initial content of beverage soluble iron reduced by treating diatomite in accor-dance with the method of Claim 1.
15. A filter aid comprising granulated diatomite which has had its initial content of beverage soluble iron reduced by treating the diatomite in accordance with the method of Claim 2.
16. A filter aid comprising granulated diatomite which has had its initial content of beverage soluble iron reduced by treating the diatomite in accordance with the method of Claim 7.
17. A filter aid comprising granulated diatomite which has had its initial content of beverage soluble iron reduced by treating the diatomite in accordance with the method of Claim 9.
18. A filter aid comprising granulated diatomite which has had its prior content of beverage soluble iron reduced by treating the diatomite in accordance with the method of Claim 12.
19. A method of producing vegetable based beverages which comprises filtering a beverage through a filter aid, said filter aid having had its initial content of beverage soluble iron reduced prior to such filtration by treating the filter aid in accordance with the method of Claim 1.
20. A method in accordance with Claim 19 wherein said filter aid comprises diatomite.
21. A method as in Claim 20 wherein the vegetable based beverage is beer.
22. A method as in Claim 20 wherein the vegetable based beverage is wine.
23. A method as in Claim 20 wherein the vegetable based beverage is ale.
24. A method as in Claim 20 wherein the vegetable based beverage is a fruit juice.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA315,206A CA1110105A (en) | 1978-10-31 | 1978-10-31 | Low beverage soluble iron content filter aid and method for its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA315,206A CA1110105A (en) | 1978-10-31 | 1978-10-31 | Low beverage soluble iron content filter aid and method for its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1110105A true CA1110105A (en) | 1981-10-06 |
Family
ID=4112809
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA315,206A Expired CA1110105A (en) | 1978-10-31 | 1978-10-31 | Low beverage soluble iron content filter aid and method for its production |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1110105A (en) |
-
1978
- 1978-10-31 CA CA315,206A patent/CA1110105A/en not_active Expired
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Legal Events
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| MKEX | Expiry |