NON-STALING GUM COMPOSITION

Abstract: The present invention relates to a gum composition exhibiting improved shelf life and resistance to staling, and which comprises a substantially anhydrous mixture of a gum base, at least one sugar alcohol, and glycerin, the glycerin being present in an amount ranging from about 8% to about 18% by weight of the composition. The gum composition preferably contains no more than 2% by weight of water. The invention includes a method for preparing the gum composition, comprising treating the ingredients thereof, including the glycerin, to remove substantially all water therefrom, thereafter combining the sugar alcohol with the glycerin under agitation and at an elevated temperature, and adding subsequently thereto the gum base, after which certain additive materials, such as flavourings, and the like may be added with mixing. The compositions of the present invention retain softness and desirable chewing sensation after storage in atmospheres of low relative humidity, for periods of time of up to one year. The present composition and method of preparation do not adversely effect the other desirable properties of the gum compositions, and both regular chewing gums and bubble gums may be prepared in this way. The present invention is particularly useful in the instance where sugar-free gum compositions are contemplated.

Description: This invention relates to gums, including chewing gums and bubble gums, and more particularly to such gums that exhibit improved resistance to staling and hardening. Chewing gums and bubble gums have been prepared in the past, with the purpose in mind of extending their shelf life. Characteristically, gums prepared and stored, even at room temperature for extended periods of time, tend to lose their moisture and elasticity, with the result that they become brittle, and initially crumble when they are placed in the mouth. This problem is particularly noticeable in the instance of sugarless gums, and particularly those gums that are stored in a dry atmosphere, i.e. an atmosphere having less than from 50 to 60% relative humidity. Sugarless gums conventionally contain of the order of about 5% by water (see for instance, United States Patent No. 3857965). It is believed that brittleness or the phenomenon of staling results from the loss of that water, due to evaporation or otherwise, over a period of time. Specifically, most sugarless gums contain large amounts of sorbitol, which serves conventionally as a sweetener, as well as a bulking aid. Sorbitol is known for its tendency to dissolve in the presence of even small amounts of water, and its tendency to re-crystallize when the water in which it is dissolved is removed. It is therefore believed that, as the water containing the sorbitol in the gum composition is lost by evaporation or otherwise, the sorbitol crystallizes out and thus promotes the embrittlement of the gum composition, so contributing to the staling phenomenon. Thus far, the only workable approach to prolonging gum composition freshness relied on the use of fin-seal packaging with water vapour impermeable laminates to exclude all external ambient atmosphere and accompanying moisture and conversely to prevent the egress of moisture from the package contents. This approach is very costly and has its limitations, as periodic package leakage permits staling to occur unabetted as before. USP 3857965 is concerned with the problem of producing a low moisture content gum with an increased shelf life. The solution taught by this document is a method in which sorbitol is included in a chewing gum composition in liquid form either by melting or by concentration of a solution. This document also teaches the use of glycerin in amounts from 0 to 10% by weight as a water substitute and as a retardant for the recrystallisation of the sorbitol. Chewing gum compositions prepared using this method are hard, waxy and inflexible. A need therefore exists to develop a gum composition that is flexible yet resistant to staling and thus offers improved shelf life, without the need to use air-tight sealed packaging. According to a first aspect of the present invention there is provided a solid, flexible gum composition having improved resistance to staling and hardening, comprising a substantially anhydrous mixture of a gum base, at least one sugar alcohol in the solid state and glycerin, wherein the glycerin is present in an amount of from 8 to 18% by weight and the sugar alcohol is present in an amount of from 40 to 75% by weight calculated on the total weight of the gum composition and the total water content in any form of the gum composition does not exceed 2% by weight. Preferably, the gum base, which may be selected from chewing gum bases and bubble gum bases, is present in an amount by weight of from 15% to 30%, the sugar alcohol is present in an amount of from 40% to 75% by weight, and the glycerin is present in an amount of from 8% to 15% by weight. The gum composition may also contain the usual additives, such as sweeteners, plasticizers, flavourings, bulking agents, fillers, mineral adjuvants and the like. Preferably the sugar alcohol is selected from sorbitol, mannitol, xylitol, and mixtures thereof. According to a preferred embodiment of the present invention, there is provided a gum composition having improved resistance to staling and hardening, comprising a mixture of the following ingredients: (a) from 15% to 30% by weight of a gum base containing water in an amount less than 3.5% by weight; (b) from 8% to 15% by weight of glycerin having a water content of less than 1% by weight; (c) from 40% to 75% by weight of a sugar alcohol in the solid state having a water content of less than 0.7% and selected from sorbitol, mannitol, xylitol and mixtures thereof; and (d) from 0.6% to 1.5% by weight of a flavouring; wherein said gum composition contains a maximum of 2% by weight of water. Preferably, sorbitol is present in an amount not exceeding 70%, mannitol is present in an amount not exceeding 15%, and xylitol is present in an amount not exceeding 65%, the percentage of each sugar alcohol being by weight, based on the total weight of sugar alcohol. Preferably, the sugar alcohol comprises sorbitol in an amount ranging from 40% to 75% by weight of the final composition. According to a second aspect of the present invention there is provided a process for preparing a gum composition according to the first aspect of the present invention, which comprises blending together at an elevated temperature the gum base, the glycerin and one or more sugar alcohol which is in the solid state at the elevated temperature. The process may comprise the steps of: (a) mixing the glycerin and the solid sugar alcohol with agitation at an elevated temperature; (b) adding the gum base to the mixture produced by step (a) and continuing agitation to form a uniform mixture; and (c) allowing the mixture to cool. The process requires substantially anhydrous conditions and preferably is performed in a dry atmosphere. Also, the gum base, glycerin and sugar alcohols are preferably treated before mixing to remove substantially all water from them. Preferably, glycerin is utilized in USP (United States Pharmacopoeia) grade, in which form it is substantially anhydrous. The sugar alcohols utilized in the present compositions preferably comprise sorbitol, mannitol, xylitol and appropriate mixtures, and are preferably dried prior to blending. The gum compositions exhibit sufficient plasticity and softness, and retain these qualities over time, without the presence of water, a known softening agent. Thus, the present compositions may be exposed to low relative humidity for extended periods of time that may range for as long as one year. Flavour sensation, chewability and other properties of the gums, including film formation in the case of bubble gums, is not adversely affected. The gum compositions of the present invention exhibit improved shelf stability and resistance to staling, and do not require air-tight packaging to exhibit this improved staling resistance. The gum compositions exhibit the improved resistance to staling without diminution of the favourable characteristics of chewing gums and bubble gums. The gum compositions may be prepared by a process which may be simply and inexpensively practised, and which effectively reduces the water content of the gum compositions to within 2% by weight of the entire composition. As indicated above, the present invention pertains to a gum composition having improved shelf life and resistance to staling or hardening. The gum bases useful in the present invention include those gum bases utilized, respectively, for chewing gums or bubble gums. Both gum bases employ a number of elastomeric materials as part thereof. Such elastomers include synthetic gums or elastomers such as butadiene-styrene copolymers, polyisobutylene and isobutylene-isoprene copolymers; natural gums or elastomers such as chicle, natural rubber, jelutong, balata, guttapercha, lechi caspi, sorva, guttakay, crown gum, perillo, or mixtures thereof. Among these, butadiene-styrene copolymers, polyisobutylene, isobutylene-isoprene copolymers or mixtures, are frequently used. The gum base usually includes an elastomer solvent, which may be selected from terpene resins, such as polymers of a α-pinene or β-pinene; rosin derivatives including hydrogenated or partially hydrogenated derivatives, such as the glycerol ester of polymerized rosin, alcohol esters of rosin, such as the glycerol ester or hydrogenated rosin, the pentaerythritol ester of hydrogenated rosin, the pentaerythritol ester of partially hydrogenated rosin, the glyceryl esters of partially hydrogenated rosin, the glyceryl ester or rosin and mixtures thereof. The gum base may include a non-toxic vinyl polymer, such as polyvinyl acetate and its partial hydrolyzate, polyvinyl alcohol, and mixtures thereof. When utilized, the vinyl polymer preferably has a molecular weight of from about 3,000 up to and including 94,000. The base may include an oleaginous plasticizer, such as hydrogenated vegetable oil, cocoa butter, natural waxes, petroleum waxes (such as the polyethylene waxes), paraffin waxes, and microcrystalline waxes with melting points higher than 80°C, or mixtures thereof. These materials may be utilized generally as softeners. The gum base may include mineral adjuvants such as calcium carbonate, magnesium carbonate, alumina, aluminium hydroxide, aluminium silicate, talc, tricalcium phosphate and the like; as well as mixtures thereof. These mineral adjuvants may serve as fillers and texturizing agents. Fatty acids may also be included, to serve as softeners, and suitable fatty acids include stearic acid, palmitic acid, oleic acid, and mixtures thereof. The gum bases also frequently include emulsifiers, particularly those that are compatible with the vinyl polymer if included in the base. Particularly, lecithin, glyceryl monostearate, fatty acid monoglycerides, diglycerides and triglycerides, glycerol triacetate, propylene glycol monostearate and mixtures thereof may be used. The gum base composition may also include conventional additives such as antioxidants, preservatives, colourants and the like. For example, titanium dioxide may be utilized as a colourant, and an antioxidant such as butylated hydroxytoluene, butylated hydroxyanisole, propyl gallate, and mixtures thereof, may also be included. Naturally, the gum bases may be prepared for a variety of products, including conventional gums and bubble gums, and the invention is not limited to a specific gum base formulation. The above descriptin is therefore presented for purposes of illustration only. Regardless of the gum base employed, the gum composition of the present invention generally includes such gum base in an amount of from 15% to 30% by weight of the total composition. In addition to the ingredients listed above, which can be included on the gum base, the gum compositions may also include a variety of adjuvant materials, such as plasticizers, softeners, fillers, thickeners, and, of course, various flavours. Useful plasticizers or softeners include lanolin, propylene glycol, glycerol and the like, and mixtures of these, and are included optionally to achieve the desired texture and consistency of the final gum composition. Fillers such as calcium carbonate, magnesium carbonate, talc and the like, as well as those materials mentioned earlier as mineral adjuvants, may be further included in the overall gum composition to provide body to the product. The gum compositions may also contain thickeners, employed alone or in conjunction with other softeners. The thickeners include methyl cellulose, alginates, carrageenan, xanthan gum, gelatin, carob, tragacanth, locust bean, and carboxy methyl cellulose. Softeners or plasticizers, such as those materials set forth earlier, may also be included. In addition, ingredients such as corn syrup as well as hydrolyzed cereal solids, may be included in the composition. The gum compositions may contain a variety of flavours alone or in mixture with each other, depending upon the type of gum composition. Particularly flavours useful in the present invention include essential oils, such as cinnamon, spearmint, peppermint, birch, anise and the like; natural fruit flavours derived from the essence of fruits, such as apple, pear, peach, strawberry, cherry, apricot, orange, watermelon, banana and the like; bean-derived flavours, such as coffee, cocoa and the like; wine-derived flavours, such as curacao zin and the like; and pungent materials, such as affinin, pepper, mustard and the like. The flavour component is usually added in a range of from 0.6% to 1.5% by weight of the entire gum composition, and typically is present in an amount of 1.0%. The gum compositions generally contain a sweetener which frequently comprises a large proportion by weight of the entire gum composition, particularly in the instance where bubble gum compositions are being prepared. In the instance of sugar sweetened gum, the sweetener generally comprises sugar (including sucrose), glucose (corn syrup), dextrose, invert sugar, fructose and mixtures thereof. In the instance where a sugarless bubble gum is prepared, the sweetener comprises a sugar substitute, including saccharin and its various salts such as the sodium or calcium salts; cyclamic acid and its various salts such as the sodium salt; the dipeptide sweeteners such as aspartame; dihydrochalcone; glycyrrhizin; Stevia rebaudiana (Stevioside); and sugar alcohols such as sorbitol, sorbitol syrup, mannitol, xylitol and the like. Also, the nonfermentable sugar substitute (hydrogenated starch hydrolysate) described in US-E-26959, may be utilized, as well as the synthetic sweetener 3,4-dihydro-6-methyl-1,2,3-oxathiazin-4-one-2,2-dioxide or its potassium, sodium or calcium salts, as described in DE-A-2001017. Any of the foregoing sweeteners may be present alone or in combination with each other. As mentioned earlier, the sugar alcohols, including sorbitol, xylitol, mannitol and the like, are utilized not only as sweeteners, particularly in the instance of sugar-free gum compositions, but also serve as bulking agents, and therefore frequently comprise a major amount by weight of the total composition. In particular, the sugar alcohols may comprise as much as 75% by weight of the total gum composition, and it is in this area that the difficulty with staling has been observed. Specifically, gum compositions conventionally contain a significant percentage of water, included as a softener, and is frequently added together with the sugar alcohols during the final preparation of the composition. The loss of water over time, particularly in atmospheres of low relative humidity, causes the sorbitol to crystallize out and, as noted earlier, contributes to the hardening of the gum compositions and the resulting staling sensation. In accordance with the present invention, water is all but entirely absent from the present gum compositions, and glycerin is added in amounts ranging from 8% to 18% by weight of the total composition. Preferably, the glycerin is used in anhydrous form, such as commercially available in USP grade. Glycerin is available as a syrupy liquid with a sweet warm taste and having a sweetness of about 60% that of cane sugar. As glycerin readily absorbs moisture, the glycerin utilized in the present invention should be maintained under substantially anhydrous conditions throughout the preparation of the present gum composition. Preferably, the glycerin is present in an amount of from about 8% to 15% by weight. The glycerin contains water in an amount by weight that does not exceed 1.0%. The sugar alcohols used in the present invention contain water in an amount by weight that does not exceed 0.7% and the gum base includes water in an amount not exceeding 3.5% by weight. In a preferred embodiment of the present invention, the gum composition comprises a gum base selected from chewing gum bases and bubble gum bases, in an amount of from 15% to 30% by weight, flavour in an amount of from 0.6% to 1.5% by weight, and glycerin in an amount of from 8% to 15% by weight, the balance comprising a sugar alcohol selected from sorbitol, mannitol, xylitol and mixtures thereof. The gum composition contains no more than 2%, by weight thereof, of water in any form. As mentioned above, the ingredients of the gum composition are preferably treated to remove substantially all water therefrom. Thus, the gum base and the sugar alcohols may be dried by heating under vacuum. In particular, the gum base, which is conventionally previously melted at temperatures that may range from 90° to 100°C, may be heated at a temperature ranging from 80° to 90°C at a vacuum less than about 400 mm Hg, for a period of time sufficient to render the base substantially anhydrous ie. to a water content of less than 3.5% by weight. For example, the gum base may be heated under these conditions for a period of about thirty minutes just prior to mixing with the remaining ingredients of the gum composition. Both the glycerin and the sugar alcohol may be dried in similar fashion to the gum base, by heating, for example, at a temperature of from 60° to 70°C under a vacuum of less than about 40 mm Hg. If pre-drying is practised, it is preferably conducted overnight, and just prior to the formulation of the gum composition. Pre-drying is not necessary, however, if the materials are provided initially in dry form as defined herein ie. having the water contents specified. After the foregoing materials are treated as described above, the sugar alcohols, in the event that a mixture is utilized, are preferably heated to a temperature of approximately 50°C while undergoing agitation or mixing, for a period of time such as three minutes. For example, sorbitol and mannitol may be combined and blended in this fashion. The glycerin may then be added to the above mixture, and mixing may be continued, for example at the same temperature, for a period of time sufficient to form a uniform mixture of the ingredients, and preferably for about eight minutes. Thereafter, the gum base, previously melted as indicated, and preferably maintained under vacuum just prior thereto, may be added to the resulting mixture, and mixing may thereafter continue for a further period sufficient to form a homogeneous mixture of all ingredients added thus far. Thus, for example, mixing may be continued for a period of time of about ten minutes. Finally, heating is discontinued, and the remainder of the ingredients, if any, to be added to the composition, including the flavouring, colourant if any, and other adjuvants, are added, and the resulting composition is then mixed for a period of time, for example a period of time as high as thirty minutes, to form a fully uniform composition. The mass is then removed from the mixer and is allowed to cool further, and may thereafter be formed into various final shapes by known gum manufacturing techniques. For example, the mass may be rolled in contact with a conventional dusting medium, such as calcium carbonate, mannitol, talc and others. The gum compositions of the present invention may be prepared into all of the various end forms known commercially, including slab form, cube form and centre-filled form. All of the techniques associated with the preparation of the products in these forms are known per se, and the present method may vary somewhat, depending upon the specific end product to be manufactured, without departing from the essential parameters relating to the exclusion of water to the limits specified. While the present invention is broadly applicable to the preparation of all gum compositions resistant to staling, it finds particular utility in the instance where sugar-free gum compositions are contemplated. These compositions, as noted earlier, frequently contain large amounts of sugar alcohols such as sorbitol and are therefore most susceptible to staling in the manner described earlier. Thus, for example, a sugarless substantially water-free chewing gum may be prepared from a mixture of the following ingredients in the following amounts, in weight %: A preferred sugarless chewing gum composition contains the following ingredients in the following amounts, also expressed as weight percent: Gum Base (dried) 19-26 Glycerin (anhydrous) 10-13 Sorbitol (dried) 60-70 Flavour Oil q.s. 1.0. The foregoing compositions and their respective ranges may natually be varied by the inclusion of adjuvant materials, such as those described earlier herein. The present invention will now be illustrated by the following Examples. EXAMPLE I A sugarless chewing gum composition which contained the following ingredients in the following amounts, expressed by weight percent, was prepared: Gum Base 20.7 Glycerin (U.S.P.) 13.5 Mannitol 18.2 Sorbitol 46.1 Cinnamon Flavour 1.5 The gum composition was prepared by blending the sorbitol and mannitol in a mixer heated to 50°C, for three minutes. Prior to blending, the sorbitol and mannitol were dried under a vacuum of less than 40 mm Hg and a temperature ranging from about 60° to about 70°C, overnight, to remove trace amounts of water. Thereafter, the glycerin, which had been dried in similar fashion, was added to the mixture of sorbitol and mannitol, and all of the ingredients were thereafter mixed for an additional eight minutes. The gum base, which had been previously prepared under a dry atmosphere and heated under low vacuum at a temperature of from about 80° to about 90°C for approximately thirty minutes, was then added to the resulting mixture of glycerin and sugar alcohols, and the resulting combination of ingredients was mixed for a further ten minutes. Thereafter, heating of the mixture was discontinued, the cinnamon flavour was added, and the mass was then mixed for an additional thirteen minutes. Thereafter the mass was removed from the mixer, permitted to cool and rolled in the presence of calcium carbonate to form the final gum product. A gum product having a similar composition was stored at 0% relative humidity for a period of one year, and when tested by chewing thereafter, was found to retain its flexibility and organoleptic acceptability. EXAMPLES II AND III The following gum compositions, comprising, respectively, a chewing gum composition and a bubble gum composition, and containing the following ingredients in the following amounts, in weight %, were prepared: Bubble Gum Bubble Gum Base 18 Glycerin 13.5 Sorbitol 32.5 Mannitol 8.0 Xylitol 27.0 Flavour 1.0. Each of the above formulations was prepared in accordance with the method outlined above, and, in particular, in Example I above. Thus, the gum base was prepared to a water content of less than 3.5%, the glycerin was prepared with a water content of less than 1.0% and the sugar alcohols were prepared to possess water contents, respectively, of less than 0.7%. Both compositions represent essentially sugarless gum formulations, and exhibited the favourable improvement in resistance to staling, noted with respect to the composition of Example I. As noted earlier, the present gum compositions and associated methods of their preparation, are particularly useful in the instance where the gum product is stored for extended periods of time in conventional packaging, in atmospheres having a low relative humidity, i.e. a relative humidity of less than 50-60%. In the instance where the relative humidity exceeds this level, conventional gum preparations and their associated conventional packaging is adequate, as water loss is substantially reduced.

Claims: A solid, flexible gum composition having improved resistance to staling and hardening, comprising a substantially anhydrous mixture of a gum base, at least one sugar alcohol in the solid state and glycerin, wherein the glycerin is present in an amount of from 8 to 18% by weight and the sugar alcohol is present in an amount of from 40 to 75% by weight calculated on the total weight of the gum composition and the total water content in any form of the gum composition does not exceed 2% by weight. A gum composition according to claim 1, wherein the glycerin is present in an amount of from 8% to 15% by weight. A gum composition according to claim 1 or 2, wherein the glycerin has a water content of less than 1.0% by weight. A gum composition according to any one of claims 1 to 3, wherein the gum base is selected from chewing gum bases and bubble gum bases. A gum composition according to any preceding claim, wherein the gum base is present in an amount of from 15% to 30% by weight of the gum composition. A gum composition according to any preceding claim, wherein the gum base has a water content of less than 3.5% by weight. A gum composition according to any preceding claim, wherein the said sugar alcohol is sorbitol alone, mannitol alone, xylitol alone, a mixture of sorbitol and mannitol, a mixture of sorbitol and xylitol, a mixture of mannitol and xylitol, or a mixture of sorbitol, mannitol and xylitol. A gum composition according to claim 7, wherein sorbitol is present in an amount not exceeding 70% by weight, mannitol is present in an amount not exceeding 15% by weight, and xylitol is present in an amount not exceeding 65% by weight. A gum composition according to any preceding claim, wherein the sugar alcohol has a water content of less than 0.7% by weight. A gum composition according to any preceding claim, further including at least one additive selected from sweeteners, plasticizers, flavourings, bulking agents, fillers, mineral adjuvants, and mixtures thereof. A gum composition according to claim 11, wherein a flavouring is present in an amount of from 06% to 1.5% by weight of the composition. A method in which a gum composition according to any preceding claim is produced under substantially anhydrous conditions. A method according to claim 12, in which the gum base, glycerin and sugar alcohol are treated before mixing to remove substantially all water therefrom. A process for the preparation of a gum composition according to any one of claims 1 to 11, which comprises blending together at an elevated temperature the gum base, the glycerin and the one or more sugar alcohol, which is solid at that elevated temperature. A process according to claim 14, which comprises the steps of: (a) mixing the glycerin and the solid sugar alcohol with agitation and heating to an elevated temperature; (b) adding the gum base to the mixture produced by step (a) and continuing agitation to form a uniform mixture; and (c) allowing the mixture to cool. A process according to claim 15, wherein step (a) is carried out at a temperature of approximately 50°C. A process according to claim 14, 15 or 16, wherein prior to step (a) the sugar alcohol and the glycerin are dried at a temperature of from 60° to 70°C under vacuum, and for a time of the order of eight hours. A process according to any one of claims 14 to 17, wherein the gum base is heated at a temperature of from 80° to 90°C and at a low vacuum, just prior to the performance of step (b). A process according to claim 18, wherein the gum base is heated for about thirty minutes. A process according to any of claims 14 to 19, wherein, after step (b), heating is discontinued and at least one flavouring is added to the mixture. A process according to claim 20, wherein after the flavouring is added and thoroughly mixed in, the resulting mixture is permitted to cool and is rolled in the presence of a dusting medium to form the gum composition.

Inventors: RIEGER, MARTIN MAX, YANG, ROBERT KUO-HOW
Applicants: WARNER-LAMBERT COMPANY
Application year: 1982
Main classification: A23G3
IPC codes: G11B5, A23G4