CARBONATION AGENT

Abstract: Dry, stable carbonating agents comprised of a carbohy­ drate/metal bicarbonate complex are disclosed. The complex is prepared by reacting a carbohydrate with a metal hydrox­ ide or oxide at a temperature not exceeding 25°C to form a carbohydrate/metal hydroxide adduct to which carbon diox­ ide is then introduced to form the complex. The complex is then immediately dried, preferably by freezing it to below its eutectic temperature and freeze dried. The carbonating agents are particularly useful as components of dehydrated beverage powders. Upon rehydration, the complex releases carbon dioxide and carbonates the beverage.

Description: 1. Field of the Invention This invention pertains to the field of dry carbonating agents and the means for preparing them. More particularly, the present invention relates to methods of preparing, isolating and using dry, stable complexes of carbohydrate/metal bicarbonate which contain bound water. These carbon dioxide-carrying complexes can be admixed with other dehydrated materials and such mixtures can thereafter be reconstituted as carbonated beverages or used in other applications in which effervescence is desired. 2. Description of Related Art Compounds which have been utilized as carbonating agents in dry form have generally included inorganic carbonates or bicarbonates, the most common of which is sodium bicarbonate. Other agents have included sodium carbonate, potassium carbonate and calcium carbonate. However, these substances have generally been found to be unacceptable when present in amounts sufficient to provide a desirable level of carbonation to a beverage because upon release of carbon dioxide by contact with an acid, the corresponding sodium, potassium and calcium salts result in an undesirable brackish and/or metallic taste. More particularly, sodium bicarbonate provides a mole ratio of carbon dioxide to sodium ion of at most 1:1, whereas sodium carbonate releases only one mole of carbon dioxide for every two moles of sodium ion. The use of sodium salts, moreover, is not recommended for health reasons, for according to medical literature excess sodium causes, among other afflictions, hypertension. Potassium carbonate also yields two moles of the potassium ion for each mole of carbon dioxide released and again results in a salty taste. Calcium carbonate too only provides a mole ratio of 1:1 of carbon dioxide to calcium ion upon release and while it does not produce a distinctly salty taste, in high concentrations it imparts a metallic off-flavor to beverages. It is also insoluble in water, which further reduces its desirability as a carbonating agent. While calcium bicarbonate could be used to provide a theoretical mole ratio of carbon dioxide to calcium ion of 2:1, free calcium bicarbonate is unstable, and it is believed that it has never been isolated in dry form. Accordingly, as a means of avoiding the presence of metallic ions in carbonating agents and their corresponding disadvantages organic carriers for carbon dioxide have been sought. In U.S. Patent No. 3,441,417, a hydroxy carboxylic acid is reacted with phosgene gas to obtain an ester carbonating agent. U.S.Patent No. 3,649,298 describes methods of making disodium salts of N-carboxy amino acids to be used in combination with anhydrides in beverage concentrates. This process also requires phosgene. The use of phosgene, however, produces products which may cause toxicological problems. Consequently, these products are also undesirable. US-A-2603569 claims an effervescent beverage concentrate comprising a mixture of an organic acid-disaccharide complex and an inorganic carbonate-disaccharide complex, said acid-disaccharide complex being prepared by raising the temperature of a mixture of an organic acid and a disaccharide containing an amount of water equal to from about 5% to about 15% of the weight of the acid present to a temperature of from about 52°C (125°F) to about 121°C (250°F); said carbonate-disaccharide complex being prepared by subjecting a mixture of an inorganic carbonate and a disaccharide, containing from about 3% to about 30% of water based on the total weight of the carbonate-disaccharide mixture to a temperature of from about 52°C (125°F) to about 138°C (280°F) for a period of from about 5 to about 30 minutes. US-A 3965273 claims a dry carbonated beverage concentrate for preparing a carbonated beverage comprising: a) a dry carbonation source which comprises a solid suspension of finely-divided calcium carbonate dispersed within a matrix of a water-soluble carbohydrate wherein the calcium carbonate has an average primary particle size of less than about 100 millimicrons and is subtantially free from aggregates in excess of about 10 microns, b) a dry non-toxic acid, and c) a flavourant. In non-food effervescent applications, while the level of metallic salt content may not be of critical importance, a compound with only a 1:1 mole ratio of carbon dioxide to metallic ion may be economically undesirable because of the amount of such carbonating agent required to achieve a particular carbonation effect. SUMMARY OF THE INVENTION The present invention substantially avoids the disadvantages discussed above and provides a method for preparing and isolating a dry, stable carbonating agent complex one mole of which contains at lease one to two moles of carbon dioxide which is readily released upon contact with water. Withour wishing to be bound by theory, it is believed that the general formula of the complexes prepared by the processes of the present invention is: [carbohydrate] a · [M(HCO₃) b ] · [H₂O] c where "a" is either 1 or 2; "b" is 1 or 2; "c" is 3, 4 or 5; and M is a metallic cation, in which the metal bicarbonate is stabilized by being part of the carbohydrate matrix. In general, the carbonating agent complex of the present invention is formed by reacting a carbohydrate with a metallic hydroxide or oxide at a temperature not exceeding 25°C to first form a carbohydrate/metal hydroxide adduct. Carbon dioxide is then introduced and reacted with the adduct to form the carbonating agent complex. The complex is then immediately dried to form the dry, stable carbonating agent of the present invention. DETAILED DESCRIPTION OF THE INVENTION Generally, the carbohydrates which are applicable in the present invention include mono-, di-, and polysaccharides and polyols. These include but are not limited to pentoses, hexoses, of the monosaccharides such as glucose, dextrose, mannose, fructose, galactose, talose, gulose, ribose, arabinose, lyxose, xylose,. Disaccharides such as maltose, cellobiose, lactose, sucrose, are also applicable. Dextrin, glycogen, starch, cellulose, polydextrose, raffinose, are typical of the polysaccharides which are applicable. The polyols include sorbitol, glycerol, mannitol, D-xylitol, dulcitol and the like. One or more of these carbohydrates may be used in combination in the reaction mixture. For preparing the complexes, a carbohydrate solution of up to 60% by weight may theoretically be used, but such a concentrated solution is very viscous and difficult to manipulate. Moreover, the carbon dioxide content of a complex produced using such a high carbohydrate content is generally low. Accordingly, preferred concentrations for the aqueous carbohydrate solution are up to 45% by weight, and preferably from about 2 to 35% by weight, depending upon the particular carbohydrate being employed and the extent of its aqueous solubility. When the carbohydrate concentration is low for a specific carbohydrate, the general tendency of the complex produced is to have a high mole ratio of carbon dioxide to metallic cation, but a lower amount of carbon dioxide release. At or near the saturation level for a particular carbohydrate both the mole ratio and the amount of carbon dioxide released are lower. For dilute solutions, the mixing of two different carbohydrates may be beneficial. The metallic hydroxides or oxides employed in the present invention may be those of the alkali or alkaline earth metals. Particularly preferred are calcium hydroxide or oxide for food applications. The calcium ion does not impart a salty taste and is one of the essential minerals needed by the human body. Other applicable hydroxides or oxides include those of potassium, sodium, magnesium, barium, etc. One skilled in the art can readily ascertain which of the cations belonging to these two groups are food acceptable and employ either the hydroxide, oxide, or mixtures thereof accordingly. Any one or more of these hydroxides or oxides may be used simultaneously. In one method for preparing the carbonating agent complex of the present invention, an aqueous carbohydrate solution as described above is first prepared and a metal hydroxide or oxide is then added to the solution while stirring until the pH of the solution is in the range of from about 9 to 12. The reaction temperature is maintained at less than 25°C, perferably in the range of from about -5° to 10°C and most preferably about -2° to 4°C. A carbohydrate/metal hydroxide adduct is thus formed in solution. Carbon dioxide, preferably in gaseous form, is then introduced into the reaction medium until the pH drops to a value of from about 7 to 10 thereby forming a portion of the carbohydrate/metal bicarbonate complex and carbonate precipitates. Another portion of the hydroxide and/or oxide is then added to the reaction medium to again raise the pH to the above noted range of about 9 to 12 and form additional adduct and carbonate precipitate. Carbon dioxide is then once again introduced to lower the pH to the range of 7 to 10 and form still more complex. This procedure is repeated until at least from about 0.25 to 3 times the original amount, on a molar basis, of metal hydroxide or oxide to carbohydrate have been added and a final pH of between 7 to 11 and preferably 9 to 10 is obtained. The reaction mixture, still maintained at the above noted temperatures, is then filtered to remove any precipitated material such as the insoluble carbonates, preferably through a chilled filter and under a carbon dioxide blanket to avoid possible product degradation. The complex, which is recovered in the filtrate, is very unstable in solution and readily decomposes with release of carbon dioxide. Consequently, it should be isolated rapidly by drying the filtered reaction medium. While drying techniques such as spray drying, drum drying and vacuum drying may be employed, possible product degradation may occur with such drying means. Accordingly, the most preferred means for drying and thereby isolating the complex is to immediately freeze the filtered reaction solution followed by freeze drying. Preferably, the solution containing the complex is frozen to below its eutectic temperature at which point the water activity of the complex approaches zero. Generally, the solution is frozen to a temperature in the range of about -10° to -40°C by means well known to those skilled in the art. The frozen material is then freeze dried in any conventional manner. Generally, the platen temperature of the freeze dryer is in the range of about 10° to 40° and at a pressure of about 3 x 10³ to 1 x 10⁴ Pascals (about 30 to 100 m bars). The freeze drying is continued to form the isolated, dry and stable carbonating agent complex of the present invention having a moisture content of about 3 to 10% by weight. For convenience, this first method for preparing the carbonating complex will be referred to hereinafter as the "pH control" method. The carbonate precipitate removed during the filtration step may be heated, if desired, to form the oxide thereof which may then be recycled for further use. In an alternative method of the present invention, the carbonating agent complex is prepared by employing a mole ratio of carbohydrate to metal hydroxide or oxide in an amount of from about 1:0.25 to 1:3 with the ratio of 1:0.5 to 1:1 being preferred. Applicants have found that this method forms complexes which are somewhat more stable than those formed by the first embodiment. Generally, in this embodiment too, a carbohydrate solution described above having a concentration of up to about 45% by weight is first cooled to a temperature of less than 25°C, preferably from about -5° to 10°C and most preferably to about -2° to 4°C. A metal hydroxide and/or oxide as described above is then added to the carbohydrate solution in a stoichiometric amount having a mole ratio of carbohydrate to hydroxide or oxide of from 1:0.25 to 1:3 to form the carbohydrate/metal hydroxide adduct. If necessary, the reaction medium is then filtered in the manner described above. Carbon dioxide, preferably in gaseous form, is then bubbled through the reaction medium until the pH is lowered to a value of about 7 to 11 and preferably to about 9 to 10. Generally, this requires that the reaction medium be saturated with the carbon dioxide. Once the complex has been formed, it is isolated from the reaction medium by drying in a manner similar to that described above. As in the former embodiment, the further processing steps should be performed expeditiously to prevent product degradation. Isolation by freezing and then freeze drying is still the preferred means for obtaining the dry, stable carbonating agent complex. For convenience, this alternative method for preparing the carbonating complex will be referred to hereinafter as the "stoichiometric" method. Both of the above embodiments may be carried out by either batch or continuous processing systems. Jacketed feed tanks and pumps may be employed to feed the reactants to pressurized jacketed reaction vessels equipped with agitation means. Recirculation lines may also be employed to ensure completeness of reaction. A sparger assembly may also be connected to the recirculation line for addition of carbon dioxide which may be pressurized by means of a back pressure control valve. After the complex has been formed, it may be passed through a jacketed filter which may include means for washing any precipitate removed from the filtrate. The reaction products produced by the methods of the present invention are not necessarily pure. Thus, in addition to the desired carbonating complexes, by-products of the reaction such as various carbonates, salts, extraneous complexes and the like may also be present in the resulting reaction product. It is not necessary to remove these "impurities" from the reaction product in order to effectively use the carbonating complexes contained within the product. Moreover, for any specific combination of a particular carbohydrate and a metal hydroxide or oxide, one or more different carbonating complexes may be formed each of which, however, have the desired characteristics of being a dry, stable carbonating agent and, in addition, are believed to have the general formula: [carbohydrate] a · [M(HCO₃) b ] · [H₂O] c where "a" is 1 or 2; "b" is 1 or 2; and "c" is 3, 4 or 5; and M is a metallic cation. The formation of more than one specific complex is particularly prevalent where more than one carbohydrate and/or metal hydroxide or oxide is employed. Thus, the carbonating agent of the present invention may comprise, in addition to impurities, a mixture of individual complexes, each individual complex contained therein having effervescent qualities. In general, applicants have found that the pH control method for preparing the carbonating agents produces a purer product than that obtained by the stoichiometric method. For example, essentially pure sucrose/calcium bicarbonate having the formula: [C₁₂H₂₂O₁₁]₂ · [Ca(HCO₃)₂] · [H₂O]₃₋₅ can be obtained using the pH control method. Applicants have determined that the mole ratio of carbon dioxide to metallic cation obtained for a given reaction product is indicative of its purity. In the case of a calcium complex, for example, a pure calcium bicarbonate complex is expected if the product has a CO₂/Ca⁺² mole ratio of 2.0. A smaller mole ratio may indicate the presence of a mixture of calcium bicarbonate/H₂O complex and/or calcium carbonate complex and/or the calcium salt of the carbohydrate or even calcium carbonate. The purity of a particular complex is dependent upon the nature of the reactants, the preparation and isolation methods used to prepare the complex, and the conditions employed. Generally, the carbonating agent complexes prepared by the present invention are able to release approximately 40 to 100 ml of carbon dioxide for each gram of complex. It has been found that, when all else is kept constant, the pH and temperature of the reaction play a role in the attributes of the final product. Generally, the higher the pH at which the reaction is carried out, the smaller the mole ratio of carbon dioxide to metallic cation in the complex, although more carbon dioxide may be available for release per gram of product. This is believed to be due to the formation of the carbonate complex which is more favorable at a higher pH. Even more importantly, however, is the pH value at the end of the reaction. Generally, the final pH of the reaction should be in the range of from about 7 to 11. Preferably, the final reaction pH is in the range of from 9 to 10 which is the most optimum for obtaining the bicarbonate complex. At lower pH values, there is generally less carbon dioxide content in the product and the product is somewhat less stable. At higher pH values, there is a higher carbon dioxide content but the mole ratio of carbon dioxide to metal cation decreases and approaches 1.0. Generally, the dry, stable carbonating complexes prepared by the present invention are very fine, white powders although the color may vary from a pale yellow to light brown if particular polysaccharides are used. Depending upon the carbohydrate(s) and metal hydroxide(s) used, the melting point of the particular carbonating complex will, of course, vary. So too, the purity of the complex will also affect the melting point obtained. Generally, applicants have been found that the melting point can vary from a low of about 143°C to a high of about 272°C. Set forth in Table A below is a list of various carbonating complexes prepared by the methods of the present invention. Due to the instability of these complexes in water, applicants have not been able to successfully purify the reaction products. Accordingly, the samples below were tested as is and were not purified so as to isolate pure, individual complexes. The melting points therefore may be those of a mixture of complexes derived from reacting the specific reactants in the manner noted. Furthermore, the complexes do not exhibit a sharply defined melting point. Even with sucrose/calcium bicarbonate which is prepared in essentially pure form using the pH control method, the melting process appears to involve several steps. Its structure collapses at about 70°C; CO₂ gas is released at about 100°C; the material turns brown at about 170°C; and finally liquefies at about 200°C. It is this latter liquefaction temperature which has been recorded below for all of the respective samples. Bulk density measurements of a number of the complexes prepared by the present invention are set forth below in Table B. As with the melting point data in Table A, the samples were tested "as is" and may include impurities which were not able to be removed. The data was obtained by measuring volume displacement using mineral oil as a medium. The complexes may be stored in an air-tight, moisture-free environment at ambient temperature for at least 12 months without any substantial decomposition. Upon contact with water, the complexes readily decompose to release carbon dioxide, the carbohydrate and the corresponding metal carbonate. In turn, the carbonate will decompose to generate further carbon dioxide if it is in an acidic environment. The complexes of the present invention may be used in food applications as a carbon dioxide carrier for a dry mix of carbonated and isotonic drinks, as a whipping agent to prepare, for example, whipped cream, as a foaming agent such as in hot cocoa mix or cappuccino, or as a dispersing aid to improve, for example, the dispersibility of cocoa powder. The carbonating agent complexes may also be used for non-food applications as well. Thus, a barium complex although not suitable for food or beverage applications, may be used as a means for ingesting suitable amounts of barium into the body for x-ray application. In fact, the carbonating agent complexes of the present invention may be used in any application in which the release of carbon dioxide is desirable upon the addition of water. Depending upon the particular application, the amount of complex added to a dry component system may vary from 10 to 85% by weight to provide a specific carbonation or effervescent effect. Of course, inasmuch as a major constituent of the carbonating agent of the present invention is a carbohydrate such as sucrose, the sugar content of the remaining ingredients for a particular application should be reduced accordingly. Having described the basic concepts of this invention, the following Examples are set forth to illustrate the same. They are not, however, to be construed as limiting the invention in any manner. The gas volumes are expressed in terms of ml/min measured at standard temperature and pressure. EXAMPLE I 100 g of sucrose are added to 300 g of water and the solution is cooled to 4.9°C. Calcium hydroxide is added to the solution in small portions with good stirring until the pH is 10.2. Gaseous carbon dioxide is introduced at a rate of 700 ml/min until the pH is lowered to 9.0. Calcium hydroxide is then again added to raise the pH to 10.2 and carbon dioxide is then introduced again to lower the pH to 9.0. This procedure is repeated until 25 g of calcium hydroxide are added and the mole ratio of sucrose to calcium hydroxide is 1:1.5. The final pH of the reaction medium is 9.0 and the total reaction time is 28 minutes. The reaction medium is then filtered using Whatman No. 41 filter paper (20-25 µm) at a filter temperature of 0°C using a CO₂ blanket. The filtrate is then frozen to -20°C using a dry ice/acetone bath and stored for 4 hours at -40°C. The product is then freeze-dried at a platen temperature of 15°C at a pressure of 1 x 10⁴ Pascals (100 m bars) for 36 hours to a moisture content of 7.1% by weight using a Model 50-SRC Virtis freeze dryer. One gram of the complex contains 41.0 mg calcium ion and 45.5 ml carbon dioxide corresponding to a mole ratio of carbon dioxide to calcium ion of 1.8. The melting point of this complex is 200° ± 1°C. The carbonating agent complex of this Example has a high mole ratio of carbon dioxide to calcium ion and a high level of carbon dioxide release. It may be used as a foaming agent, for example, in instant coffee. EXAMPLE II A 40% by weight sucrose solution is reacted with calcium hydroxide and carbon dioxide in the same manner as set forth in Example I. The final mole ratio of sucrose to calcium hydroxide is 1:0.87. The temperature of the reaction is maintained at 0°C and carbon dioxide is added at a rate of 725 ml/min. The pH of the reaction is alternately varied in the range of from 7.8 to 9.5 with the final pH of the reaction medium being 7.7. Total reaction time is 65 minutes. The product is filtered through a filtering apparatus maintained at a temperature of 23°C. The filtrate is then frozen and freeze-dried in a manner similar to that set forth in Example I. The carbonating agent complex has a final moisture content of 3.3% by weight and contains per gram 25.9 mg calcium ion and 24.8 ml carbon dioxide, corresponding to a mole ratio of carbon dioxide to calcium of 1.5. As compared to the product of Example I, this product has a lower carbon dioxide content and a lower mole ratio of carbon dioxide to calcium ion due to the relatively high filtration temperature of 23°C which may give rise to some degradation of the resulting product. EXAMPLE III 100 g of sucrose are added to 233 g of water and the aqueous solution is cooled to a temperature of 4°C. 5.6 g of calcium hydroxide are added to form a sucrose/calcium hydroxide adduct corresponding to a mole ratio of sucrose to calcium hydroxide of 1:0.25. Gaseous carbon dioxide is then bubbled through the adduct solution at a rate of 700 ml/min until the pH drops from an initial value of 12.1 to a value of 9.4. The total time of the reaction is 20 minutes. The reaction medium is then quick frozen by means of dry ice and freeze-dried in a manner similar to that set forth in Example I. The dry, stable product has a moisture content of 7.2% by weight and contains per gram 26.4 mg calcium ion and 24.9 ml carbon dioxide corresponding to a mole ratio of carbon dioxide to calcium ion of 1.7. The complex has a melting point of 215° ± 2.1°C. As compared to the previous Examples, a lesser amount of calcium hydroxide is employed in making the complex of this Example. This results in a lower carbon dioxide content. The product texture is comparatively more fluffy and less stable. EXAMPLE IV Calcium hydroxide is added to a 33% by weight aqueous sucrose solution in a mole ratio of sucrose to calcium hydroxide of 1:1.1 at a temperature of 1°C. Carbon dioxide is introduced into the sucrose/calcium hydroxide adduct solution at a rate of 725 ml/min until the pH drops from an initial value of 12.6 to 9.5. The product is then isolated by freezing and freeze-drying in the manner set forth in Example I. One gram of the complex contains 79.5 mg calcium ion and 84.7 ml carbon dioxide corresponding to a mole ratio of carbon dioxide to calcium ion of 1.8. The melting point of this complex is 227° ± 4.9°C. EXAMPLE V In this Example, the method set forth in Example I is repeated under various processing conditions. The results are set forth in Table I below: The Examples in this table demonstrate that the optimum total solids content in the reaction mixture for a sucrose/calcium system is in the range of from about 15 to 35% by weight. Outside of this range, carbonating complexes are still prepared but with somewhat lower CO₂ content. This table also demonstrates the need for maintaining the filter at a low temperature so as to minimize product degradation which results in lower CO₂ content. Note Sample Nos. 1 and 6. Sample 6 shows an even more noticeable effect caused by high filtration temperature due to its higher sucrose content which causes an increase in viscosity and correspondingly lower filtration rate. This results in a lower CO₂ content and a lower mole ratio of carbon dioxide to calcium ion. The benefit of using a CO₂ blanket during filtration is also demonstrated (see Sample No. 3). By using a CO₂ blanket, product degradation is minimized even at a lower final pH value which generally tends to favor less stable products. EXAMPLE VI The procedure of Example I is repeated with different carbohydrates. The results are set forth in Table II below: This table demonstrates the applicability of various carbohydrates to prepare the carbonating agent complexes of the present invention. EXAMPLE VII In this Example, the method set forth in Example III is repeated under various processing conditions. The results are set forth below in Table III: This table demonstrates that as the mole ratio of sucrose to calcium hydroxide decreases, the carbon dioxide content in the final product increases while the ratio of carbon dioxide to calcium ion decreases. EXAMPLE VIII In this Example, the effect of pH, particularly the final pH of the reaction medium, is shown for both the method of Example I (Table IVA) as well as the method of Example III (Table IVB). Except for the differences in the pH parameter, all of the remaining parameters remain constant for each of the two methods employed. Table IVA, which sets forth the results of the pH control method at various pH conditions, shows that as the pH increases, the carbon dioxide content is generally higher and the ratio of moles of carbon dioxide to calcium ion decreases. Moreover, it is seen that the composition of the complex generally depends upon the final pH value and not the reaction pH range. Accordingly, essentially the same complex can be obtained regardless of the reaction pH range, provided the final pH is kept the same. The optimum final pH value is seen to be in the range of about 9 to 10. Table IVB, which sets forth the results of the stoichiometric method at various pH conditions, shows that a final pH value of about 9 to 10 is also optimum for this method as well. EXAMPLE IX In this Example, the effect of time elapsed between the end of the reaction and the start of freezing the reaction medium for subsequent freeze-drying is shown for each of the two embodiments of the present invention by settings fourth the amount of carbon dioxide lost as a result of decomposition. Time Elapsed (min) % CO₂ Lost Example I Method Example III Method 0 0 0 5 15.3 0 10 49.7 1.7 20 67.9 3.5 30 76.3 12.6 EXAMPLE X A. Samples of carbonated maltose, sucrose and dextrose all prepared by the method of Example I, are ground and stored with and without a mixture of 8% citric acid in amber glass bottles, having plastic screw caps. The bottles containing samples are stored for 29 weeks, one set being maintained at -16°C, 1 set at 6°C, one set at 23°C and the final set at 38°C. The bottles are opened once a week for testing and visual examination. After 29 weeks, all samples of the three carbonated sugars visually appear unchanged with the exception of the carbonated sucrose and dextrose samples which were stored at 38°C, which caked. The carbon dioxide content of all three carbonated sugars remains constant with time and temperatures of -16°C, 6°C and 23°C, respectively. At 38°C, all the carbonated sugars with citric acid lose from 10 to 30 % of their carbon dioxide content in 6 weeks and then stabilize, i.e., lose no further carbon dioxide, at about 10 weeks. These tests indicate the importance of storing the carbonating agent complex out of contact with atmospheric moisture. They additionally show that the complex may start to decompose at high temperatures accompanied by long storage times. B. Samples of ground (about 50 mesh) sucrose/calcium bicarbonate complex prepared by the method of Example I are stored alone and in combination with various ingredients at various temperatures in an air-tight foil pouch having a thickness of .00035 mm for 12 months before being opened. The amount of degradation of the complex expressed as carbon dioxide lost is shown below: SAMPLES % CO₂ Lost -16°C 6°C 23°C 38°C Complex alone 0 0 0 20 Complex with 8% by weight citric acid 0 0 0 20 Orange soda mix with 31% by weight of complex 0 0 0 9 Cappuccino with 10% by weight of complex 0 0 8 33 EXAMPLE XI Various metallic sucrose bicarbonates are prepared using a variety of different inorganic hydroxides. The method of Example I is repeated with the exception that the metal hydroxides listed below are substituted for the calcium hydroxide. The respective CO₂ contents and mole ratios for each complex are set forth in Table VI below: METALLIC SUCROSE CARBONATES M(OH)₂ CO₂(ml/g) (CO₂/M) moles Ba(OH)₂ 49.0 1.4 Mg(OH)₂ 50.4 1.4 KOH 98.0 0.6 NaOH 62.3 0.6 EXAMPLE XII In this Example, the effect of different drying techniques is illustrated: A. Freeze Drying Calcium hydroxide is added to a 30% by weight aqueous sucrose solution in a mole ratio of sucrose to calcium hydroxide of 1:0.75 at a temperature of 4°C. Gaseous carbon dioxide is introduced at a rate of 600 ml/min. The total reaction time is 30 minutes and the final pH is 10. The product mixture is immediately frozen and stored at -40°C for 2 hours in a Vitro Model 50-SRC freeze dryer. The product is then freeze-dried at a platen temperature of 30°C for 18 hours. The resulting complex contains 64 ml of carbon dioxide per gram of complex and a mole ratio of carbon dioxide to calcium ion of 1.7. B. Spray Drying The reaction is carried out as in Part A above. At the end of the reaction, the mixture is introduced into a spray dryer at the rate of 953 g/min within 5 seconds under a CO₂ atmosphere. The conditions of the spray dryer are as follows: Equipment: Proctor and Schwartz Spray Dryer Inlet airflow: 56.6 standard m³/min Inlet temperature: 150°C Chamber temperature: 75°C Outlet temperature: 65°C Air broom on "2" High air velocity, two fluid nozzle The residence time of the sample in the dryer is less than 30 seconds, however the product is actually dried in about 50 m sec. The complex produced has 69 ml of carbon dioxide per gram of complex and a mole ratio of carbon dioxide to calcium ion of 1.97. As compared to the technique using freeze drying, the spray drying technique of this example produces a product which has an even higher CO₂ content and mole ratio of CO₂/Ca⁺². C. Drum Drying The reaction is again carried out as in Part A above. At the end of the reaction, the mixture is introduced into a drum dryer at the following conditions: Vacuum: 0.13 x 10⁵ - 0.16 x 10⁵ Pascals (100-120 mm Hg) Inlet temperature: 93.3°C Outlet temperature: 93.3°C Steam pressure: 0.304 x 10⁵ Pascals (0.3 atmospheres) Drum distance: 0.305 mm Drum speed: 0.5 rpm The dried carbonating agent complex has a carbon dioxide content of 42 ml per gram of product and mole ratio of carbon dioxide to calcium ion of 1.2. There is still enough carbon dioxide in the complex to provide adequate carbonation for many different applications. EXAMPLE XIII A dry instant orange shake mixture is prepared in accordance with the following formulation in which the calcium bicarbonate/sucrose complex prepared in Example I acts as a dispersing agent. Calcium bicarbonate/sucrose 30.4% by weight Sugar 32.7% Non-fat dry milk solids 20.2% Orange juice solids 9.6% Citric acid 5.6% Flavor and color additives 1.5% This instant orange shake mix is used in an amount of 110 grams per liter of water. EXAMPLE XIV In this Example, fructose/calcium bicarbonate complex prepared in Example VI is employed as a foaming agent in a dry instant coffee drink mix. Milk solids 43.2% by weight Sugar 26.8% Fructose/calcium bicarbonate 14.8% Instant coffee 11.1% Cocoa powder 2.6% Citric acid 0.9% Flavor additives 0.6% The dry instant coffee drink mix is used in an amount of 150 grams per liter of water. EXAMPLE XV In this Example, the dextrose/calcium bicarbonate complex prepared in Example VI is employed as a carbonating agent for an orange soda dry mix. Sugar 53.4% by weight Dextrose/calcium bicarbonate 35.3% Citric acid 10.7% Orange flavor and color 0.6% The orange soda dry mix is used in an amount of 100 grams per liter of water to provide a carbonated orange soda. EXAMPLE XVI A dry non-salty tasting antacid is prepared by mixing 8.5 grams of maltodextrin/calcium bicarbonate complex with 1.5 grams of citric acid. The powder is pressed into 5 gram tablets. When added to water, the tablets dissolve to form a pleasant tasting antacid solution. EXAMPLE XVII A dry isotonic drink mix is prepared by mixing the following ingredients: Sodium bicarbonate/fructose 0.14 g Magnesium bicarbonate/fructose 0.04 g Potassium bicarbonate/fructose 0.19 g Calcium bicarbonate/fructose 0.07 g Fructose 4.00 g Citric acid 0.58 g

Claims: A method for preparing a dry, stable carbonating agent complex comprising: (a) admixing a metal hydroxide, oxide or mixture thereof with an aqueous carbohydrate solution at a temperature of less than 25°C to form a carbohydrate/metal hydroxide adduct; (b) adding carbon dioxide to the solution to react with the adduct and form a carbohydrate/metal bicarbonate complex in the solution; and then (c) isolating the complex from the solution by drying. The method of Claim 1, further comprising: (a) admixing a sufficient amount of the metal hydroxide, oxide or mixture thereof to the carbonate solution which is maintained at a temperature of from -5° to 10°C until a pH of from 9 to 12 is obtained; (b) adding sufficient carbon dioxide to the solution containing the carbohydrate/cation hydroxide adduct until the pH is lowered to the range of from 7 to 10; (c) repeating steps (a) and (b) until between 0.25 to 3.0 moles of said hydroxide, oxide or mixture thereof has been added for each mole of carbohydrate present in solution and a pH of from 7 to 11 is obtained; (d) filtering the mixture; and then (e) drying the filtrate to obtain the dry, stable carbohydrate/metal bicarbonate complex. The method of Claim 1, further comprising: (a) adding the metal hydroxide, oxide or mixture thereof to the carbohydrate solution in an amount such that the mole ratio of carbohydrate to cation is from about 1:0.25 to 1:3.0 to form the adduct; and (b) saturating the solution containing the adduct with carbon dioxide to form the complex in the solution. The method of Claim 3, wherein after the solution is saturated with the carbon dioxide, the pH is in the range of from 7 to 11. The method of Claim 1, wherein the carbohydrate is sucrose. The method of Claim 1, wherein calcium hydroxide, calcium oxide or a mixture thereof is added to the carbohydrate solution. The method of Claim 1, wherein an alkali or an alkaline earth metal hydroxide, oxide or a mixture thereof is added to the carbohydrate solution. The method of Claim 1, wherein the solution is chilled to below its eutectic temperature and then freeze dried. The method of Claim 1, wherein the complex is isolated by spray drying or drum drying. A dry, stable carbonating agent composition comprising a complex of a carbohydrate/metal bicarbonate having the formula: [carbohydrate] a · [M(HCO₃) b ] · [H₂O] c in which M is a metallic cation, a is 1 or 2, b is 1 or 2 and c is 3, 4 or 5, characterized in that said complex decomposes upon contact with water to release carbon dioxide, the crabohydrate and the corresponding metal carbonate. The carbonating agent of Claim 10, wherein the metallic cation is selected from the group consisting of the alkali and alkaline earth metals. The carbonating agent of Claim 10, wherein the carbohydrate is selected from the group consisting of arabinose, glycerol, xylose, cellobiose, corn starch, corn syrup, dextrin, talose, gulose, ribose, dextrose, dulcitol, fructose, galactose, lactose, maltose, mannose, raffinose, mannitol, soluble starch, cellulose, glycogen, sorbitol, sucrose, glucose, polydextrose, and D-xylitol. The dry, stable form of sucrose/calcium bicarbonate having the formula: [sucrose]₂ · [Ca(HCO₃)₂] · [H₂O]₃₋₅

Inventors: SO, REBECCA SUI-CHUN, WILLI, ALBERT ANTON
Applicants: SOCIETE DES PRODUITS NESTLE S.A.
Application year: 1985
Main classification: A23L2
IPC codes: C07H23, C01B31, A23F5, A23L2