Effervescent mixture characterized by protracted release of gas and the use of this mixture in the preparation of carbonated drinks
SUMMARY OF THE INVENTION 
     The invention refers to an effervescent mixture in powder or granulated or compressed form useful for the prolonged liberation of gas, at least one component of which is coated with a film containing a water-soluble polymer, preferably a macromolecular watersoluble polysaccharide. 
     The invention also refers to a process for the preparation of a carbonated mixture useful for the prolonged liberation of gas, as hereinabove described, which comprises coating at least one of the components of the mixture with a film containing a water-soluble polymer. 
     Finally, the invention refers to a water-soluble composition in powder or granulated or compressed form for the preparation of carbonated drinks, characterized in that it contains, as an ingredient, an effervescent mixture in powder or granulated form at least one component of which is coated with a film containing a water-soluble polymer. 
     BACKGROUND OF THE INVENTION 
     Many basic powder compositions used for the preparation of both medicinal and thirst-quenching drinks are currently available commercially. 
     In general, carbonated drinks are prepared by dissolving CO2 under relatively high pressure in the liquid to be consumed. Maintaining the initial quantity of dissolved gas to which such drinks owe their &#34;tingling&#34; and thirst-quenching effect, necessitates the use of hermetically sealed containers which are capable of withstanding the internal pressure and are therefore relatively heavy and bulky, even for small quantities. 
     Effervescent mixtures in powder form are known which produce the same type of effect as that described above, with the exception that supersaturation of the liquid phase is virtually impossible under the conditions in which such drinks are usually prepared. It is impossible, using known mixtures, to prepare drinks in which CO2 is evolved at a constant rate throughout the entire period required for consumption. After the initial effervescence has occurred, a drink prepared in this way rapidly loses its character and becomes &#34;flat&#34; and even insipid. The invention permits the drawbacks associated with known effervescent mixtures to be overcome advantageously. 
     PREFERRED EMBODIMENTS OF THE INVENTION 
     It has been discovered that a carbonated drink in which a gas (CO2) is evolved throughout the entire average period required for consumption may be obtained by using an effervescent mixture at least one component of which is coated with a film containing a water-soluble polymer. In the absence of such a coating, the effervescent mixture begins to liberate all its gas immediately upon contact with water, until the aqueous phase is saturated with CO2, the excess gas escaping into the atmosphere. 
     The water-soluble polymer may be, for example, a cationic copolymer derived from dimethylaminoethyl methacrylate and neutral aliphatic esters. A cationic copolymer, such as EUDRAGIT E 100, derived from dimethylaminoethyl methacrylate and neutral aliphatic esters of methacrylic acid, such as the methyl or butyl ester, may be used advantageously. Such products are known and may be obtained from specialized dealers. They are used principally in the pharmaceutical industry for coating active components with a rapidly disintegrating gastrosoluble film. Hence, they are perfectly tolerated by the body, non-toxic, and may therefore be used in compositions in powder or granulated or compressed form for the preparation of drinks without any special restrictions. The ratio of water-soluble film to mixture used should be calculated to produce a total, prolonged liberation of gas, generally of the order of 15 to 40 minutes. The effervescent mixture in powder form is generally coated by the usual techniques, such as spraying or the so-called fluidized bed process. 
     Certain water-soluble polymers may give rise to secondary phenomena, such as whitish cloudiness or overall coloration. Such phenomena are preferably acceptable in the case of opaque or deep-coloured drinks. In other cases, however, and particularly when a clear, pale-coloured aerated drink is required, it is preferable to use a macromolecular water-soluble polysaccharide as the water-soluble polymer. 
     The specific object of the invention is to obtain an effervescent mixture in powder or granulated or compressed form useful for the prolonged liberation of gas, characterized in that it has at least one component in the form of particles coated with a film containing a macromolecular water-soluble polysaccharide. A preferred coating film includes gum arabic or tragacanth gum, or a mixture of these two gums. 
     To obtain the effervescent mixture, salts or mixtures of salts of alkali or alkaline earth metals and carbonic acid and mineral or organic acids or mixtures thereof, currently known and used in the foodstuffs, and pharmaceutical industries may be used. For example, mixtures are used which contain sodium bicarbonate and one or more organic acids, such as tartaric acid and citric acid, or sodium bicarbonate and a mineral acid, such as phosphoric acid. The particles may also contain a mixture of acids, for example, carbonic acid and an amino acid. 
     According to the invention, an effervescent mixture in powder or granulated or compressed form useful for the prolonged liberation of gas is prepared by first dissolving the macromolecular polysaccharide in a concentrated saccharose syrup. Generally, a 100/60 to 100/50 (wt./wt.) syrup is used, and approximately 100 parts by weight of the polysaccharide are dissolved in approximately 150 to 400 parts by weight of the concentrated syrup. 
     Once a homogeneous liquor is obtained, a volume of 95% ethanol equal to the volume of water used in preparing the concentrated syrup is added gradually. This yields a whitish liquor which, in certain cases, it may be advisable to stabilize by storing it in an airtight container for 1 hour at a temperature of approximately 50° C. The coated product may be coloured by adding a food colorant to the liquor. This coloration provides a check on the uniformity of the coating. 
     An essential oil or a mixture of essential oils may also be incorporated in the liquor to impart an aroma to the mixture obtained after coating. In such cases, the above-mentioned essential oils may be advantageously incorporated in the liquor after dissolution in the above-mentioned volume of ethanol. 
     The proportions may be varied according to the origin and nature of the raw materials, but the proportion of sugar used must be sufficient to prevent the polysaccharide from solidifying in a lump on contact with the alcohol. 
     This liquor may be applied to one of the components whose function is to bring about liberation of CO2 by reaction, by the usual techniques, such as spraying or the so-called fluidized bed process. 
     Presented in powder or granulated or compressed form, effervescent mixtures coated in this way may be used as the basis for aeration of the most varied types of acidulated drinks. 
     The consumer of drinks aerated in this way may adjust the rate of liberation of CO2 and, consequently, the tingling effect to suit his personal taste, by simply stirring the liquid gently with a straw. 
     Without stirring, the discharge of CO2 is constant but not excessive; only a minimal quantity of gas escapes from the surface. If the drink is left standing for 10 minutes the consumer will find that it has not become flat but saturated at the ambient atmospheric pressure. The slightest stirring will increase the production of CO2 and confer a &#34;tingling&#34; sensation similar to that of bottled drinks aerated under a pressure of several atmospheres. 
     These results are obtained by using an effervescent mixture containing 1.20 g of sodium bicarbonate and sodium monophosphate per 100 ml of drink. 
     Apart from the above-mentioned ingredients, the composition in powdered or granulated or compressed form for the preparation of aerated drinks may also contain essential oils, such as oil of cinnamon, oil of lemon, and oil of orange, adsorbed on a solid support, in variable proportions depending on the required flavour and aroma. It may also contain suitable food colorants, sugar--preferably instant sugar, or any other additive necessary to achieve the desired organoleptic effects. 
     All the essential ingredients are mixed in proportions such that 2.5 to 14 g of the final composition suffice for the preparation of 100 ml of aerated drinks, the weight depending upon whether the drink is Diet or Soft. 
     The following examples provide a more detailed illustration of the invention without, however, limiting it. 
    
    
     EXAMPLE 1 
     Two equivalent of sodium bicarbonate were coated with a water-soluble polymer film of EUDRAGIT E 100 (registered trademark of Rohm &amp; Haas, Pharma GmbH, Darmstadt, Federal Republic of Germany) by the so-called fluidized bed process (proportions: approximately 25 g of EUDRAGIT E 100 for 100 kg of basic product). 
     The powdered product obtained was then mixed with 1 equivalent of tartaric acid. 
     EXAMPLE 2 
     One equivalent of powdered tartaric acid was coated with a water-soluble polymer film as described in Example 1. 
     The powdered product obtained was then mixed with 2 equivalents of sodium bicarbonate. 
     EXAMPLE 3 
     A mixture of tartric acid (1 equivalent) and sodium bicarbonate (2 equivalent) have been coated, seperately, with a water soluble polymer film described in example 1. 
     An analogous effect was observed when the tartaric acid in the above examples was partially or completely replaced by an equivalent quantity of citric acid. 
     The same effect was also achieved when the above-mentioned organic acid was partially or completely replaced by an equivalent quantity of sodium monophosphate. 
     EXAMPLE 4 
     25 g of gum arabic are incorporated in a sugar syrup obtained by dissolving 25 g of sugar in 15 g of water. 
     After thorough mixing, 15 ml of 95% ethanol are added. The liquor then assumes a whitish tinge. 
     If desired, this liquor may be coloured, for example by adding corn starch caramel or a caramel colorant. 
     If desired, the mixture obtained may be stored in an airtight container for 1 hour at 50° C. before application of the coating. 
     Sodium bicarbonate in powder form is then coated by thoroughly mixing the particles with the liquor obtained as above, in the proportions of 1 ml of liquor to approximately 10 g of bicarbonate. 
     After thorough mixing, this mixture is pressed through a mould or a sieve in order to obtain uniform granules of the required cross-section which are subsequently dried for 2 to 3 hours in a hot-air oven controlled at 50° C. 
     EXAMPLE 5 
     20 g of tragacanth gum are added to a syrup obtained by dissolving 25 g of sugar and 25 g of sugar caramel in 75 ml of water. After thorough mixing, 25 ml of 95% ethanol are added. 
     The liquor obtained is stored in an airtight container for 1 hour at 50° C., and then treated as described in Example 4. 
     If required, the colour of the liquor may be intensified by adding a caramel colorant. 
     Two equivalents of coated sodium bicarbonate granules are mixed with 1 equivalent of tartaric acid. When placed in aqueous medium, the effervescent mixture obtained liberates CO2 for a period of 20 to 30 minutes, which seems adequate. This period may be prolonged by applying thicker coatings. 
     The particles may also be coated with tartaric acid by the same method. 
     EXAMPLE 6 
     A liquor was prepared from the following ingredients, following the procedure described in Example 4: 
     
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sugar                  40    g                                            
caramel                10    g                                            
gum arabic             40    g                                            
tragacanth gum         10    g                                            
water                  75    ml                                           
95% ethanol            30    ml                                           
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     After thorough mixing, a coating was applied to a mixture of the following acids, in the proportions of 5 ml of liquor to 50 g of acid mixture: 
     
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phosphoric acid    3 g    6%                                              
tartaric acid     30 g   60%                                              
citric acid       17 g   34%                                              
                  50 g   100%                                             
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     Drying was carried out on a screen, using a current of hot air. 
     It was also observed that the liquor used in Examples 4 to 6 afforded excellent protection to hygroscopic products. It can therefore be used advantageously either as a coating product or as a support in the foodstuffs industry, for example in the manufacture of candy. 
     The foregoing examples also can be expressed on the basis of 100 parts by weight of macromolecular water-soluble polysaccharide or mixture of macromolecular water-soluble polysaccharides instead of grams. 
     Taking Example 5 as typical, it will be appreciated that the corresponding parts by weight can be expressed as follows: 
     
         ______________________________________                                    
                              Amount Based on 100                         
                              parts by weight                             
                              macromolecular or                           
                              mixture of macro-                           
                              molecular water-                            
                              soluble poly-                               
Ingredients Used                                                          
           Amount   Multiplier                                            
                              saacharides                                 
______________________________________                                    
Tragacanth Gum                                                            
           20 g     × 5 = 100                                       
Sugar      25 g     × 5 = 125                                       
Sugar Caramel                                                             
           25 g     × 5 = 125                                       
Water      75 ml    × 5 = 375                                       
           (75 g)                                                         
                    Total     625 parts by wt.                            
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     It will readily be appreciated that the mixture of sugar and sugar caramel in water, expressed in parts by weight, will be (125+125)/375=250/375=100/150. 
     With regard to Example 4 it will be appreciated that: 
     
         ______________________________________                                    
                              Amount Based on 100                         
                              Parts by weight of                          
                              macromolecular or                           
                              mixtures of macro-                          
                              molecular water-                            
                              soluble poly-                               
Ingredients Used                                                          
           Amount   Multiplier                                            
                              polysaacharides                             
______________________________________                                    
Gum Arabic 25 g     × 4 = 100                                       
Sugar      25 g     × 4 = 100                                       
Water      15 g     × 4 =  60                                       
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     Thus, it will be apparent that the mixture of sugar in water for this example, expressed in parts by weight, will be 100/60 and that the syrup of saacharide solution will be about 160 parts by weight. 
     From the foregoing examples it can be observed that the volume of 95% ethanol to water can vary from 25 ml/75 ml, or about 33%, in Example 5 to 15 ml/15 g (15 ml), or about 100%, in Example 4.