IL31359A - Algin product and process of producing same - Google Patents

Description

31359/2 _=·.=·»n->si~ ·-n"·cs«»=«»=s«·-=— «·a«" Algin product and process of producing same ADOLPH'S FOOD PRODUCTS MFG. , Co. 0:29645 This invention .relates to a process of treating algin whereby its dispersibility in water is greatly enhanced, and to the product obtained thereby.

As is well known, the term "algin" is widely used for the water-dispersible derivatives of alginic acid, which is a polymannuronate derived from common species of brown seaweed, and widely produced commercially in various parts of the world.

The most widely used algin is sodium alginate, which is the sodium salt of alginic acid. This is commercially produced in a powder form, which, regardless of whether the mesh size is fine or coarse, requires a combination of time and agitation for dispersion in. cold water. Sodium alginate eventually dissolves in water to give a colloidal solution, but the individual particles of sodium alginate swell before they dissolve, and tend to form lumps. Accordingly, complete dis^-solution takes time, which may be shortened somewhat either by the application of heat or agitation to the system, or indeed, by a combination of both.

In many applications of algins, however, it is not practicable to provide heat and agitation, as vhen a preparation containing algin is made up into a vater system intermittently, and even casually.. Examples include dessert gels intended for household use, and dental impression compounds, where a dental assistant or nurse must repeatedly make up small batches of the compound with water.

An object of the present invention is to provide a comminuted algin which is readily and quickly dispersible and dissoluble in water at room temperature, with a minimum of agitation; and to provide a process for obtaining such a product.

Further objects of the invention will become apparent as the description thereof proceeds.

The invention is applicable to any commercially available algin, most commonly and by way of example, any ground or otherwise comminuted sodium alginate, including any or all of those commonly known as "high viscosity", "medium viscosity", and "low viscosity"—these being accepted trade designations in the algin art.

As mentioned, such commercially produced algins are generally not readily and quickly dissoluble in cold water. In certain special cases, it is possible to admix the algin with a comminuted water-soluble substance such as, for example, sugar, so that the separate particles are held apart and, when such a mixture is added to water, dissolution may be facilitated to some extent. Even this procedure does not solve the problem completely, and more agitation is necessary than is desirable.

Often it is not permissible to utilize the partially favorable effects of admixing with granulated sugar and the like as mentioned. An instance is that of algin compositions intended for the preparation of dietetic dessert gels in which sweetness is imparted by saccharine or sodium cyclamate, and the use of sugar is impermissible. Dissolution is a particularly difficult problem in such instances.

Generally stated, the algin (for example., in powder form about 0.10 mm (100 microns) in particle size), is placed in a suitable blending, tumbling, or mixing device and is simultaneously tumbled and treated with water or water vapor or, indeed, both. ¾e function of the tumbling is both to insure uniform access of the water or steam to the algin and also to bring about an astonishing and wholly unforeseeable structural change In the algin which will be described in greater detail hereinbelow.

The device used may be any of the well-known blenders and tumblers commonly used for intermixing dry powders and dry granular materials. A suitable device consists of a cylindrical drum which is rotating, and which has vanes attached to the interior, so that the material is lifted towards the top of the drum and then falls down through the interior to the bottom. Portland cement mixers are mechanically suitable; they impart the desired free falling or "tumbling" action. An especially suitable device comprises two hollow cylinders o of circular cross-section which are Joined at a 90 angle, this assembly being rotated with the axes of the cylinders mounted at a ^5° angle to the horizontal axis of rotation. A typical "twin-shell" blender of this sort is shown on page 305 of the book Continuing with the illustrative embodiments, the simultaneous tumbling and hydration are continued until the algin has taken up anywhere from about 3 kilograms to about 500 kilograms of water per initial 100 kilograms of algin subjected to treatment in accordance with this invention. The best amount which has been found is approximately 200 kilograms of water per lOO kilograms of algin.

The time of processing as aforesaid will naturally vary with the rate at which the steam or water is admitted to the blender during the tumbling process and to the amount of steam eventually used. In typical cases, where the ratio is approximately two parts of water to one part of algin, about 15 minutes total tumbling and water-admittance time is sufficient. Where steam is used, the processing time is shorter, such as three or four minutes. Generally speaking, wefind that steam is best at low ratios, from about 3 to 50 kilograms water per 100 kilograms of algin, while for higher ratios, including the optimum ratio of 200:100, water is best, and it may be at room temperature, hot water being usable but offering no practical advantages over cold.

It has been found that astonishingly enough, that even with this treatment, and even at the maximum ratio of water used as aforesaid, the algin still pours out of the blender when discharged, behaving essentially as loose granular material. The swelling in volume is considerable, and. his, of course, must be taken into account when loading the blender for any particular batch. About l/2 to 2/3 kilograms of algin per liter capacity of the blender is suitable, at a 2:1 water ratio.

It is, of course, within the "broad purview of the invention to carry out the process in a continuous fashion, instead of "batch-wise. In this case it is, of course, necessary to use a blender adapted to continuous processing. Suitable apparatus is commercially available. One such mixer is essentially a multiplicity of the "twin-shell" cylinders connected end-to-end in series and rotated as a unit about a horizontal axis.

It will be readily understood that when steam is used, it is eventually taken up by the algin in the form of water. It will be understood, accordingly, that while the invention has been described in terms of liquid water, it is possible to carry out the invention, especially at low water ratios, by using water in its, vapor form, i.e., steam, and this is to be understood as Included in this disclosure and claims by the term "water" .

The macroscopic change which takes place in accordance with the treatment Just described is that the algin is agglomerated into granules which are roughly isodimensional but have a highly irregular surface, and are, in general, from about 2 mm to about 5 mm in diameter.

The material discharged at this stage of the inventive process may, of course, be used directly in that form, but the granules will contain the added water so that prompt utilization in the final aqueous solution contemplated will be necessary, to avoid microbiological spoilage.

. .Accordingly, the next step in the process, although it is an optional one, is to dry the material discharged from the tumbler by passing it through any conventional and suitable dryer, such as a tray dryer, a rotary dryer, or the like.

Preferably the algin product is brought back to its approximate starting moisture content, which is usually 3 "to 8 percent by weight. Where the minimum amount of water has been added in the first stage of the process, such as, for example, three or four kilograms of water per initial 100 kilograms of algin, the drying step may be omitted if desired. While the drying o temperature may be as high as about 100 C, a better product is obtained if relatively low temperatures are used, such as from ½5°C. to 6o°C. The drying step can also be carried out at room temperature, by using a vacuum drying apparatus or dessicators, employing silica gel, calcium chloride, or other dessicant.

The dried product may be ground, if desired, in a hammer or roller mill, to any desired particle size. Remarkably superior results are obtained at about 0.125 mm and particularly when sized to all smaller than 0.18 mm and larger, than 0.10 mm.

It is not certain vhy the inventive process brings about the remarkable change in the hydra ting properties of the algin that it does . In any case, the physical structure is completely altered . Examination under the microscope shows that commercial algins are a mixture of powdery and somev/hat fibrous particles and examination under a high power shows a relatively opaque structure. After treatment with water and tumbling in accordance with the invention, the granules have a remarkable appearance resembling fragmented amber; they are fairly translucent and the individual particles observable in the starting algin have disappeared completely .

One would ordinarily consider that a dense, relatively homogenous , translucent particle would hydrate more slowly , but astonishingly, this is not the case . Possible some initial hydration of the algin takes, place in the processing in accordance with the invention, so that even though relatively large granules are formed, these exhibit great ease of dissolution. It is possible to prepare an algin treated in accordance with the process which, subsequent to.. grinding of the granules , exhibits the same particle size analysis as the starting material, but which dissolves in cold water under any specified condition of gentle agitation or stirring, many times more quickly than the starting material. A specific instance appears under Example I hereinbelow.

In many applications of the inventive algin product, it is incorporated with other substances to form a composition for some particular use, such as food use, dental impressions, adhesives, sizings, and the like. It is within the scope of the invention to incorporate one or more optional additives along with the water in the tumbling process. Thus, where a food composition is to be prepared coloring' matter or flavoring material or both may be so added, and the uniformity and homogeneity of incorporation in the algin product will be very great. Likewise, if such materials as sodium hexametaphosphate, saccharin, and the like are used, particularly when these are water soluble, they may be likewise advantageously added at this point.

Some examples of proceeding in accordance with the invention follow; Example.1: Commercial sodium alginate, sold under the trade-name of " eltone" and having a mesh size of about 0.10 mm, and giving at one percent solution in water a viscosity of about 400 centipoises (and therefore termed a medium viscosity algin) is loaded into a 30 liter capacity twin shell blender of the type already described. 3 kg of the algin was introduced, the apparatus put into rotation, and 6 liters of water introduced over a 10-minute period. After introduction of the water, tumbling was continued for an additional 5 minutes, making a total of 15 minutes. The blender was then opened, and the processed algin was dumped out. It flowed freely and had the granular appearance already described hereinabove. The product . o o was then dried in a laboratory tray dryer at 45 C. to 55 C. overnight, to a moisture content of about 4 percent, In order to show the enhanced dispersibility achieved by the invention, tests were conducted in which 250 grams of a mixture of water with three different concentrations of the dried and ground product obtained as descrihed above were placed in a 600-milliliter glass beaker and agitated "by a laboratory-type propeller mixer operated at 700 rpm. , at a .0 , room temperature of 2h C. T e time necessary for complete dissolution of the algin, before and after treatment in accordance with the invention, was noted and appears in the table below: Example 2: The processing run of Example 1 was repeated except that in the water prior. to admitting it to the blender, 750 grams of sodium hexametaphosphate were dissolved. A product was obtained as described hereinabove. ¾e resulting algin product also had a "built-in" neutralizer for water hardness from the sodium hexametaphosphate.

Example 3: A cold-water soluble dessert gel of the "dietetic" type containing no sugar vas formulated with the algin product obtained as described in Example 1 hereinabove. ¾e following table gives the ingredients and the weights thereof, in proportions to give a quantity of the dessert composition sufficient for addition for one-half liter of water.

Ingredient For 500 cent, of Water Sodium alginate from Example 1 2.50 gm Tricalcium phosphate 0 2 Sodium hexametaphosphate l.6o Adipic acid 2.60 Saccharin o.oi Sodium cyclamate • 0 2 Cherry flavor Ο.65 Bed food color 0.02 b.25 gm When 8.25 grams of the above-formulated composition vas stirred into a half-liter of water using an ordinary kitchen mixing bovl and spoon, dissolution to give a clear, pink solution vas complete in about I5-seconds stirring; and, upon standing for an additional 15 minutes, a firm, palatable gel resulted.

Example h The formulation shown in Example 3 was carried out, except that sodium alginate from Example 2 was used, and only 0.90 grams of sodium hexametaphosphate was added to the dry mix, the sodium alginate itself already containing the remainder. The results of preparing a dessert gel using cold water were identical with those described in connection with Example 3.

Example : Sodium alginate, low viscosity grade, a commercial production of about 100 mesh, was placed in a tumbling blender equipped with a horizontal steam injection tube coinciding with the axis of rotation of the blender.

Four kg. of sodium alginate were used, and after placing the blender in rotation, live steam was introduced over a period of 15 minutes, at a rate slow enough that it was all taken up by the algin without the necessity of having to vent any live steam to the atmosphere. In this manner, the algin was allowed to take up 3½ k . of water in the form of steam condensed in and on the algin particles in the fashion already described. At the end of the 15-minute period, introduction of steam and the tumbling were stopped, and the load was discharged as a uniform, flovable granular product. Stirring tests in water showed' very rapid dispersion and even upon grinding the algin to 0.18 mm and also to 0.07 mm in a laboratory hammer mill, stirring in cold water again produced much more rapid dispersion than the starting material.

Example 6; Various compositions were formed by dry mixing of one part of the powdered algin of Example 1 with other substances as listed below. The compositions obtained are all intended to be mixed with water when used. It was found that all of the compositions mixed more readily, quickly, and lump-free with water than control samples made with the starting commercial algin.

(A): Three parts of quebracho extract and one part of bentonite, to give a boiler-water scale-inhibiting compound. (Β): Four parts of pregelatinized wheat starch and one part of polyvinyl alcohol, to give a wallpaper adhesive of reduced penetration into paper.

(C) : 0.033 parts anhydrous sodium carbonate, 10 parts powdered asbestos, and 0.50 parts anhydrous calcium sulfate, to give a molding and impression compound.

(D) : One part of urea, to give a soil-treating composition.

It will be understood that while the invention has been described with the aid of numerous ' specific embodiments in which various proportions by weight, starting materials, apparatus, and the like have been given, nevertheless, the invention is a broad one, and is not limited to specific conditions and the like, since numerous variations in materials, operating conditions, and the like are possible within the broad scope of the invention as defined in the claims which follow:

Claims (6)

31359/2** QLAIMS

1. A process of treating comminuted algin comprising the steps of tumbling said algin, and during said tumbling, introducing water and continuing said tumbling until said algin has taken the form of homogeneous granules*

2. The process in accordance with Claim 1 , wherein said water is used in proportion within the range of about 3 kg. to 500 kg. of water for each 100 kg. of algin.

3. The process in accordance with Claim 1 or 2 in which said algin is sodium alginate*

4. The process in accordance with Claim 1 , 2 or 3 in which said treated algin is subsequently dried.

5. The process in accordance with Claim 4, wherein said dried algin is ground to a dry powder.

6. Readily water-dispersible algin produced in accordance with the process of any of the foregoing Claims 1 to 5· 7· A process of treating comminuted algin as claimed in Claim 1 , substantially as described and exemplified hereinbefore.-