IL32277A - Process of clarifying and improving vegetable beverages - Google Patents

Description

PROCESS OF CLARIFYING AND IMPROVING VEGETABLE BEVERAGES The present invention is directed to a process for clarifying vegetable beverages, e.g. beer, wine and similar beverages, both alcoholic and non-alcoholic, and, more particularly, to the clarification of such beverages to remove phenolic and polyphenolic compounds, such as anthocyanogens and other tannins and their oxidation products, by the use of a crosslinked polyvinylpyrrolidone in a porous granular or porous bead form.

Most beverages of the class contemplated are subject to the production of haze, particularly when chilled during storage. For example, a beer which may be perfectly clear at room temperature may become cloudy when cooled on ice. The cloudy effect is commonly known as "chill haze and is thought to be due to the presence of protein tannin complex in the beer. In the case of wine and fruit juices, the presence of tannic acid is believed to account for a chill haze characteristic. It is therefore desirable to remove such tannins and similar phenolic and polyphenolic compounds, including the anthocyanogens and the oxidation products of such tannin materials, during the purification of the beverage in order to eliminate the haze.

In the past, beverages of this kind have been clarified principally by the employment of proteolytic enzymes which have the effect of solubilizing the chill haze protein occurring in the beer or similar beverage. Such proteolytic enzymes, however, are not completely satisfactory since upon long storage the components formed by enzymatic digestion tend to recombine in the beverage and subsequently form a haze.

One solution to this problem is disclosed in U. S. Patent 2,698,550. This patent relates to the employment of water-soluble polyvinylpyrrolidone which, when added to the beverage, is capable of forming a precipitate of the tannic acid and/or tannins, which precipitate can be removed from the beverage. This requires a very strict control of the amount of polyvinylpyrrolidone which is added. Because the polyvinylpyrrolidone is water-soluble, any excess added will dissolve in the beverage being treated. This adds an unwanted foreign substance to the beverage.

U. S. Patent 2,947,633 discloses the clarification of beer and similar beverages by the utilization of a water-insoluble polyvinylpyrrolidone to the beverage being clarified. Although a substantial improvement over previously employed, processes, the process disclosed in this patent has various limitations. The water-insoluble polyvinylpyrrolidone material used in accordance with the 32277/2 '<*> process of U. S. Patent 2, 947, 633 can only be prepared as a fine powder. Accordingly, special pressure filtration processes or centrifugation are necessary to remove the fine powder contaminate from the beverage. Therefore, the fine powder is not well suited for rapid and complete filtration and for use in a packed column or similar operations.

Similarly, U. S. Patent 3, 117, 004 discloses a process for removing tannins and similar material from vegetable beverages by the use of an insolubilized polyvinylpyrrolidone. The polyvinylpyrrolidone used is only available as a fine powder, and the process is subject to the same limitations as described above.

The art as known is discussed in U. S. Patents 3, 146, 107 and 3, 222, 180, whereby said patents are not pertinent to the invention set forth in the following paragraphs and the claims.

• It has now been discovered that vegetable beverages, e. g. beer, wine and similar beverages, can be effectively clarified to remove the unwanted haze and the "bad" taste components from wine, , by the use of a cross-linked polymer of vinylpyrrolidone wherein the crosslinked vinylpyrrolidone polymer is in the form of a porous granule or bead.

It is an advantage of the process of the present invention that the employment of granules or beads of crosslinked vinylpyrrolidone polymers for the clarification of beer, wine and similar beverages allows the clarification of such beverages to be conducted in packed columns or filtration purification systems requiring rapid filtration. It is thus preferable to prior art use of fine powdered vinylpyrrolidone polymers which require long drainage time of the liquid through the powder in the clarification of beer, wine or similar beverages.

In carrying out the process of the present inven-tion, the solution containing tannins and similar objectionable materials need merely to be contacted with the porous crosslinked vinylpyrrolidone polymer granules or beads.

This may be done simply by adding to the solution to be treated the porous granules or beads of crosslinked vinyl-pyrrolidone polymer and removing it by filtration after the complexing action has been completed. Preferably, however, the process of the present invention is carried out in a system wherein rapid throughput is obtained. The water-insoluble crosslinked vinylpyrrolidone polymer granules or beads have sufficient strength so as to make them suitable for use as complexing agents in ordinary gravity or pressure filtration systems or packed columns having the advantage of rapid throughput, with high capacity for absorbing especially the phenolic and polyphenolic com-pounds sich as anthocyanogens ana other tannins and their oxidation products.

The vinylpyrrolidone polymer employed in accordance with the process of the present invention is a water-insoluble but water-swellable, crosslinked vinylpyrrolidone polymer in the form of porous beads or granules. Such vinylpyrrolidone polymer product is re ared b a rocess which comprises the production of the crosslinked porous granules or beads of vinylpyrroli-done polymer by the polymerization of the vinylpyrrolidone monomer, with or without an additional copolymerizable monomeric material, with a crosslinking agent in an aqueous solution of an electrolyte, the monomeric materials and the polymer produced being preferably maintained in suspension, advantageously by mechanical means, e.g. agitation. Up to about 50 , preferably up to 20%, by weight of an additional copolymerizable monomer based on the amount of polymerizable reactants may be used.

Examples of suitable comonomers which can be employed are the acrylates and a-substituted acrylates, e.g. methyl, ethyl, propyl and higher alkyl, phenyl, napthyl and other aryl, the ester moiety being such as methyl, ethyl, propyl and higher alkyl, phenyl, napthyl and other aryl; vinyl ethers, e.g. methyl, ethyl, propyl and higher alkyls, acrylamide and substituted acrylamides, e.g. methacrylamide, N,N-dimethylacrylamide, and N-methyl acrylamide, acrylic acid, acrylonitrile, allyl acetate, allyl alcohol, crotonic acid, dimethylaminoethylvinyl sulfide, diethylhexyl maleate, didodecyl maleate, fumara-mide, itaconic acid, methacrylic acid, methoxystyrene, methyl vinyl ketone, 3-methyl-N-vinylpyrrolidone, 2-methyl-5-vinylpyridine, styrene, trichloroethylene, vinylcaprolactam, vinyl carbazole, vinylimidazole, vinyl laurate, vinyl benzimidazole, 1,3- and 1,4-butanediol monomethacrylate, vinyl oxazolidinone, vinyl oxyethylurea, vinyl propionate, vinyl pyridine, vinyl stearate, vinyl acetate (and the derived vinyl alcohol) .

In the production of the porous crosslinked vinyl-pyrrolidone polymer in bead or granule form, a crosslinking agent is employed in amounts of from 0.1 to about 20% by weight based upon the vinylpyrrolidone monomer. In this respect, one or more of the conventional crosslinking agents can be employed. Thus, for example, suitable crosslinking agents include the alkylenebisacrylamides, e.g. Ν,Ν'-methylenebisacrylamide, the alkylene glycol dimethacrylates, e.g. ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate , higher polyethylene glycol dimethacrylate, 1,3- and 1,4-butanediol diacrylates anddimethacrylates etc. and the polyvinyl aromatic compounds, e.g. di inyl benzene, divinylethylbenzene, divinylchlorobenzene, divinyltoluene, divinyl naphthalene, 1,3 or 1, 4-divinyloxybutane, etc.

Other suitable crosslinking agents employed in the production of the porous crosslinked granular or bead form of vinylpyrrolidone polymer employed in accordance with the process of the present invention include t allyl acrylate, p-ieopropenylstyrene, trivinyl raeseate, diallyl maleate, divinyl ether, trivinyl citrate, divinyl o-phenylene diacetate, vinyl allyl ether, diethylene glycol diallyl ether, divinyl methyl glyceryl ether, trivinyl glyceryl ether, tetravinyl pentaerythrityl ether, hexahydro-1, 3, 5-triacryl-S-triazine, vinylpyrrolidone dimers described in U. S. Patent 3,252,995, and the like.

The crosslinking agent or agents need only be those containing two or more functional groups capable of reacting in the polymerization reaction so as to form a crosslinked or three dimensional network in the polyvinylpyrrolidone product.

As stated above, the polymerization of the vinyl-pyrrolidone, with or without additional copolymerizable monomers, in the presence of a crosslinking agent is conducted in an aqueous solution of an electrolyte. Such electrolyte is employed in a concentration which must be sufficiently high as to produce phase separation before or during polymerization. A preferred aqueous electrolyte mixture contains from 5 to 80%, preferably 10 to 30%, by weight of the suitable electrolyte salts based on weight of water; for example, with sodium sulfate, about 10-20% by weight is particularly useful. Generally, alkali metal and ammonium salts such as sodium, lithium and potassium sulfate; sodium, potassium and lithium chloride; sodium, potassium, lithium and ammonium acetate, etc. are employed as the electrolyte. It is often beneficial to include a buffer such as disodium hydrogen phosphate in order to maintain the reaction mixture at neutral to slightly alkaline pH.

Since the monomers are not very soluble in such electrolyte solutions, when employing more than enough of the vinylpyrrolidone monomer to saturate the aqueous solution of electrolyte, a suspension of the excess monomers and of the polymer which is formed can be maintained through mechanical agitation.

In the polymerization process, the relative proportion of total monomer to water is determined at the upper limit by the ability of heat removal and the danger of particle agglomeration, and may be as high as about 80% monomer, preferably about 50%, based on the weight of water; the lower limit is inter alia based on convenience of operating without undue bulk and can be successfully operated with as low as 1% monomer, preferably 10%, based on the weight of water.

The polymerization process of the present invention is conducted in the presence of a catalyst which provides a source of free radicals. In this respect, any of the conventional free radical initiator catalysts generally employed in vinyl polymerizations can be employed in accordance with the process of the present invention, such catalysts being added either to the mixture of monomers polymerized in accordance with the present invention or to the aqueous solution of electro-lyte. Thus, for example, the catalyst can be any of the conventional peroxide catalysts, e.g. benzoyl peroxide. di-t-butyl peroxide, as well as the preferred azo catalysts, e.g. azobisisobutyronitrile.

While the temperature and other parameters of the polymerization process are not critical, it is generally preferred to carry out the polymerization either through the use of a single charge or incremental charges of monomeric material or by the continuous addition of monomers at a temperature of about 0° to about 100° C. in open vessels, or up to about 150* C. in pressure vessels, the time required for acceptable polymerization being up to 10 hours generally. In this process, yields of 90% or more of the porous cross-linked polyvinylpyrrolidone in bead or granular form can be produced.

As noted previously, the clarification process of the present invention is generally carried out by the use of the porous crosslinked granules or beads of vinyl-pyrrolidone polymer in packed columns or filtration purification systems requiring rapid filtration. When employed in such systems, undried beads having a size of approximately 1-7 mm. in diameter are generally employed, particles having a smaller or larger diameter can be employed where desired for particular purposes.

The process of the present invention will now be described by reference to the following specific examples.

Example 1 In order to illustrate the process of the present invention and the effective extraction or complexing of the tannins and similar materials found in beer, an experiment was conducted employing the following continuous extraction apparatus. The apparatus employed comprised a 48" glass column having an inside diameter of 1" including, above the stopcock, a glass wool plug, perforated porcelain disk and glass holddown collar. A separator funnel equipped with a capillary tube was in position at the top of the glass column so as to supply the beer through the column by gravity feed.

The porous beads employed, ranging in size from approximately 1 to 7 millimeters in diameter, were composed of vinylpyrrolidone polymer crosslinked with divinylbenzene and were in the water-swollen state (20.6% solids) obtained by eliminating a final drying step in their preparation.

The beer to be treated was lager beer which had received no previous chill-haze proofing treatment.

With the glass wool, perforated disc, and holddown collar in place, the tube was filled with distilled water. 193 grams of the swollen beads were then introduced into the tube. This amount was sufficient to provide a column of beads 24 inches long by 1 inch in diameter, occupying a tube volume of 308.7 cubic centimeters. The column of beads was stratified according to size by passing distilled water upward through the column and out the top of the tube.

After washing and stratifying the beads, the level of water in the tube was dropped to a point 1 inch above the column of beads. The separatory funnel equipped with capillary tube was filled with beer and the entire assemblage attached to the top of the extraction tube.

The extraction process was started by opening both the upper and lower stopcocks (flow rate was controlled through the lower stopcock alone) . As beer entered the tube, it gradually displaced the water already present in the column of beads, forcing the water out the bottom of the tube. At all times the level of liquid in the tube was maintained 1 inch higher than the bead column.

A total of 2484 milliliters of beer was passed through the column by gravity feed over a period of 77 minutes (flow rate=32.26 ml./min.). Discarding the first 700 milliliters of effluent to assure complete displacement of the water in the column by beer, four samples of 320-330 grams each were collected. These samples immediately were packaged in 12 fluid ounce petite style amber bottles, tightly capped, and numbered consecutively in order of their collection. After each large specimen, a 20 milliliter sample also was withdrawn, sealed in a glass vial, and numbered to correspond with the preceding bottled sample.

The bottled samples, together with two similarly packaged specimens of the beer which had not undergone treatment, were subjected to a forcing test consisting of three cycles of the following: 5 days at 100· i2° F. then 2 days at 26· ±1· F.

Upon completion of each cycle the turbidity of each sample was determined at 26° F. using a CBL (Canadian Breweries Ltd.) hazeometer calibrated to reach turbidity in terms of ppm. silicon dioxide required to produce the same degree of haze in standard aqueous dispersions. The ppm. silicon dioxide in CBL units can be converted to the more widely employed Formazin Turbidity Units (American Society of Brewing Chemists) by multiplying by a factor of 6.9.

The 20 milliliter samples of treated beer were analyzed for anthocyanogen content by the method of McFarlane, Journal of the Institute of Brewing 67, 502-506 (1961).

Both the haze readings and the analytical results are given in Table 1.

TABLE 1 Forcing Test Haze Readings (26e Cycle 1 Cycle 2 Cy Sample CBL Formazin CBL Formazin CBL Ho. Units Units Units Units Units 1 1.2 8.28 1.8 12.42 1.8 2 1.8 12.42 3.9 26.91 3.9 3 3.5 24.15 5.1 35.19 6.5 4 2.8 19.32 5.2 35.88 8.5 Control 1 > 40 >276 Z>40 ;>276 >40 Control 2 >40 >276 >40 > 276 ;> 40 It can be seen that turbidity of the beer has been reduced from a value greater than 40 (upper limit of the hazeometer) to values as low as 1.2. Testing for anthocyanogen shows that from 91.2 to 94.4% of that originally present in the beer is removed by the treatment.

Example 2 Example 1 was repeated using a fresh sample of beer, a fresh column of beads, and a flow rate of, 17.49 ml./min., about half the rate employed in the first example. With the exception of this change in flow rate and the collection of five samples rather than four, Example 2 was an exact duplicate of Example 1, not only in column preparation, extraction procedure, sampling technique, and testing, but even in the amount of crosslinked polyvinylpyrrolidone beads used to form the column and the volume of beer treated. Test results are given in Table 2. In general, results are similar to those reported for Example 1.

TABLE 2 Forcing Test Haze Readings (26e Cycle 1 Cycl e 2 Cy Sample CBL Formaz n CBL Formazin CBL No. Units Units Units Units Unit 1 1.75 12.08 2.0 13.8 1.8 2 0.6 4.14 0.7 4.83 3.0 3 2.1 14.49 2.4 16.56 4.4 4 1.2 8.28 2.0 13.8 5.9 2.0 13.8 5.0 34.5 7.0 Control 1 >40 >276 >40 >276 >40 Control 2 >40 >276 >40 >276 >40 sampl 1*31 grant of the water-swollen beads of Example 1 were added to 489 grams of lage beer which had received no previous ehill-haoe proofing treatment.

This corresponded to a concentration of approximately lb. polymer/100 barrels beer en a dry basis. The mixture in a tightly sealed container was mounted on the outer periphery of a slowly rotating wheel and agitated in this, manner for 24 hours. The mixture was vacuum filtered through Whatman #3 paper to remove the beads and the filtrate packaged in a 12 fluid ounce Canadian petite style amber beer bottle* The turbidities of both the treated sample and an untreated sample packaged in similar fashion were determined using the CSS* haaeometer, and then subjected to the forcing test described la example 1. Results are shown in Table 3.

Original forcing Tesis. Base Readings (26* F.) Base Re&diSMs Cycle 1 Cycle 2 Cycle 3 Sample cat Porm&ela CBS» Foraaain C8& Eormasin *- Ho. Units Uni e Unite smite Vnita Unit® Unite U its 1 5.0 • 34.5 36.0 248. >40 >276 Control >40 >2?6 >40 >276 >40 >276 Example 4 Example 3 was repeated using 2.62 grams rather than 1.31 grams of the same water-swollen beads in 483.2 g. of beer, corresponding to a concentration of approximately 60 lbs. polymer/100 barrels of beer on a dry basis. Results are shown in Table 4.

Table 4 Example 5 As described in Example 1, a column containing 193 grams of the water-swollen beads was prepared.

The wine to be treated was a white, dry type received from Canadaigua Industries Company Inc. in the fully fermented, but not yet modified or filtered stage. The wine was passed through a #3 Whatman filter paper prior to usage but remained in a very cloudy state.

Approximately one gallon of the cloudy wine was passed through the prepared column by gravity feed over a 35 minute period. Discarding the first 700 ml of effluent, five 7-8 fluid ounce samples and one 3-4 fluid ounce sample were collected consecutively and packaged in 8 oz. and 4 oz. clear glass bottles, respectively. The colors of the six treated samples and of an untreated control were determined using a Hellige Varnish Comparator. The samples then were placed in an air circulating oven adjusted to 50* C. and their colors again determined after 4, 7, and 14 day intervals. The less the change in color, the more effective the crosalinked porous beads in removing those substances causing discoloration of white wines on aging* Results are shown in Table 5.

Table 5 Example 6 Example 5 was repeated using a fresh column of beads, a passage time of 25 minutes, and a fresh sample of wine which had been filtered through a Hyflo Super Cel and Dicalite 115 bed to give a clean, clear filtrate.

With these exceptions Example 6 was a duplicate of Example 5. Results are shown in Table 6.

Table 6 Example 7 Absorptive Activity of Vinylpyrrolidone/acrylamide/ divinylbenzene crossli ked beads based on 60 parts vinylpyrrolidone/40 parts acrylamide.

Salicylic acid was selected as a substrate since it contains both a phenolic hydroxyl and a carboxyl group.

The phenolic group gives the substrate adsorptxve reactivity with the beads and the carboxyl group provides a means for the titration of salicylic acid with standard base.

By titrating a solution for the amount of salicylic acid present before and after the addition of the beads it is possible to determine the total amount of salicylic acid 16.8 grams wet beads (20% solids) were added to 150.0 ml 0.0992 N salicylic acid and stirred for 20 minutes then filtered rapidly. A 50 ml aliquot was titrated with 0.1188 N NaOH. 33.5 mis of the standard base were required, or 0.405 grams salicylic acid was absorbed by 3.36 grams polymer beads.

Example 8 Absorptive activity of vinylpyrrolidone/acrylamide/ divinylbenzene crosslinked beads based on 99 parts vinylpyrrolidone/1 part acrylamide.

In a manner similar to Example 9, 15.1 grams wet beads (24% solids) were added to 150.0 mis 0.0992 N salicylic acid and stirred for 20 minutes.

A 50 ml aliquot was titrated with 0.1188 N NaOH. 28.8 mis of the standard base were required, or 0.649 grams salicylic acid was absorbed by 3.62 grams polymer beads.

The process of the present invention gives excellent results in the filtration or clarification of vegetable beverages, e.g. beer, wine or similar beverages, both of an alcoholic and non-alcoholic type. Unlike the fine powdered material employed in the prior art (slow filtration rate) , the crosslinked porous granules or beads of vinylpyrrolidone polymers can be employed in packed column or filtration purification systems requiring rapid throughput.

Claims (5)

1. · A process for clarifying and improving vegetable and similar beverages, which comprises contacting said beverages with a water-insoluble, water-swellable, crosslinked vinyl -pyrrolidone polymer or copolymer, in the form of porous granules or porous beads and subsequently, after separating the beverage, regenerating the beads by elution of any absorbate from the beads.

2. Uhe process of claim 1, wherein the process comprises the separation of the treated beverage.

3. The process of claim 1, wherein the porous granules or beads before drying have a diameter of from about 1 to about 7 millimeters.

4. . The process of claim 1, wherein the beverage is beer.

5. The process of claim 1, wherein the beverage is wine. S. HOROWITZ & CO. AGENTS FOR APPLICANTS