AU688837B2 - Stable particulate sweetener compositions - Google Patents

Description

Stable Particulate Sweetener Compositions

Related Application Information

The present application is a continuation-in-part of U.S.S.N. 08/163,163 filed on December 7, 1993.

Background of the Invention

The present invention relates to the preparation of stabilized particulate high intensity sweeteners for use in dry foods and powdered beverage applications. More specifically, the present invention relates to stable dipeptide-based sweetener compositions that are formulated as stable, free flowing particles for use in the food and beverage industries.

Aspartame (APM) is a well known dipeptide sweetener manufactured and sold by The NutraSweet Company of Deerfield, Illinois, as NutraSweet Brand sweetener. Additionally, there are some foreign manufacturers of aspartame. When used herein, the term "aspartame" or "APM" refers to α-L-aspartyl-L- phenylalanine methyl ester, its' salts and metal complexes as taught in U.S. Patent Nos. 3,492,131 and 3,714,139 to Schlatter. Salts and metal complexes of APM are also disclosed in U.S. Patent Nos. 4,448,716 and 4,439,460 to Tsau et. al., 4,029,701 and 4,031,258 to Berg et. al., all of which are incorporated herein by reference.

The major application for aspartame is as a low calorie sweetener in the food and beverage industries. Aspartame powder is sold in bulk to the various food and beverage manufacturers who must then either incorporate the sweetener directly into the final product (food and dry applications) or repackage the sweetener and distribute it to the various bottlers which subsequently mix into the liquid beverage composition. Aspartame in bulk is commercially available as both powder and granulated forms. Aspartame powder per se has low bulk density and good dissolution properties. Yet, due to the very nature of its lower bulk density and small particle size, the powder is readily air-borne and oftentimes may have dusting and flow problems. The granular form has a higher bulk density and possesses good flow properties but does not always instantaneously dissolve. These properties can result in product losses and metering problems, a need for expensive packaging and overall shipping and handling inconveniences.

The present invention improves the overall stability and flowability of aspartame during shipping and storage. The dipeptide nature of the compound renders it highly susceptible to degradation by heat and other chemicals through the hydrolysis of the its peptide bonds. Long term storage or the storage of APM powder in areas of high temperatures often results in the loss of much of its sweetness as these conditions tend to bring about the cyclization of the molecule into its diketopiperazine derivative. Moreover, the powder itself is hard to handle and oftentimes some becomes lost in the environment as "dust". In the beverage industry some of the bulk aspartame powder is lost as dust in the air during handling and shipping prior to dissolution of the powder into the beverage solution during manufacture. When one is dealing in tons of aspartame per year, these can be considerable losses if left unchecked and which if reduced will result in major cost reductions. The present invention eliminates this problem.

Finally, another advantage of the stabilized APM particulate compositions of the present invention is the dissolution and dispersion of the sweetener in solution as compared with the unprocessed aspartame powder. During beverage manufacture for example, aspartame powder when mixed with the soft drink liquid has a tendency to float on the surface of the liquid and adhere to the sides of the container in which it is mixed. In non-acidified liquids, both the powder and granular forms tend to clump into a sticky mass that is not easily dispersed and dissolved. Since the high tech beverage manufacturing facilities of today require precise metering of the liquid components of the beverage to be made, such clumping is entirely unacceptable. This requires the use of equipment for agitation or stirring to mix the powder into the liquid resulting in additional processing steps and costs of manufacture.

In flavored dry mixes, for example flavored teas, coffees, powdered soft drinks the flavors such as vanilla, citrus and other similar flavors can interact with aspartame resulting in the loss of flavor and sweetness during storage. The aspartame has to be protected with a physical barrier to prevent contact and hence interaction with the flavor.

It has been surprisingly and unexpectedly found that the stability and flow properties of dry aspartame powder can be dramatically enhanced if the aspartame is first added to and suspended in water and combined with a minor amount of a stabilizing flow agent to form an aqueous suspension which is then mixed with an aqueous solution of a coating agent, said mixture being subsequently dried so that the coating agent encapsulates the aspartame/flow agent blend. Preferably the suspension is spray dried so as to form a fine, particulate encapsulated product that protects the aspartame from reacting with other flavor and chemical ingredients in dry food and powdered beverage products and enhances the sweeteners flow properties and other physical characteristics.

United States Patent No. 4,722,844 to T. Ozawa et. al. teaches the preparation of aqueous APM suspensions which are asserted to be both chemically and physically stable. In water, like most crystalline materials, APM particles sink and settle since APM's specific gravity is significantly greater than that of water. To obtain physically stable APM suspensions, this patent teaches the addition of a viscosity or specific gravity increasing component, such as food gums and polysaccharides. The patent discloses physically stable APM suspensions (2.0%-5.0%) in sugar syrups such as isomerized sugar and sorbitol. The aspartame suspensions of Ozawa et. al. '844 use an aqueous vehicle that is high in sugar, polysaccharide or food gum content, i.e. over 50%, and low aspartame content. Such a product will not be acceptable however, for use in most food applications.

United States Patent No. 4,007,288 to Glicksman et. al. discloses a readily soluble sweetening composition for use in foods and beverages wherein the aspartame is first solubilized with a bulking agent such as dextran or some other hydrolyzed starch material and the solution is then vacuum drum dried to a composite powder of sweetener and bulking agent. United States Patent No. 4,631,195 to Colliopoulos et. al. discloses another attempt at stabilizing aspartame for cooking and baking applications whereby the aspartame is co-dried with polyglucose or polymaltose. U.S. Patent No. 4,619,833 to Anderson teaches a rapidly soluble dry beverage mix in which aspartame is dry mixed with a dispersion of food acids, flow conditioners and maltodextrin. Finally, United States Patent No. 4,001,456 also to Glicksman et. al. teaches sweetening compositions in which aspartame is mixed in an aqueous solution of a bulking agent comprising an organic acid, hydrolyzed starch materials and sugars wherein the solution is then spray dried to form a fine, agglomerated APM/bulking agent powder. None of the prior art however, teaches a physically stable aspartame composition with a high APM content that is a highly flowable particulate powder for easy handling and storage that is useful in a broad range of dry food and beverage applications.

Summary of the Invention

The present invention relates to a high intensity sweetener composition and method for its preparation. More specifically, the invention comprises a stabilized dipeptide sweetener that is prepared as an aqueous suspension and mixed with a minor amount of a water soluble flow agent comprising food grade polymers, hydrocoUoids and gums to form a suspension. The suspension is then mixed with a solubilized encapsulation agent comprising maltodextrin, gum arabic, starches and the like, said mixture is then dried so that the maltodextrin or gum coats and encapsulates the aspartame/flow agent composition as a dry particulate powder. The sweetener composition exhibits superior flow and shelf stable properties and particularly lends itself to dry food and powdered beverage applications.

Detailed Description of the Invention

The ingredients and parameters that go into the preparation of the aspartame suspension which serves as the starting point in the process of the present claimed invention is more particularly and fully set forth in copending application U.S.S.N. 08/163,163 which is hereby incorporated by reference. The aspartame liquid suspension described therein is a relatively pure aqueous aspartame suspension with an APM concentration of from about 10% to 70% by weight that is physically stable under long term and adverse storage conditions as well as providing greater ease in handling than bulk aspartame crystalline powder. The problem with most APM suspensions of high aspartame concentrations, i.e. >20%, is that they become highly viscous, sticky and not sufficiently flowable for the most food and beverage applications, and particularly those requiring a particulate sweetener in its dry state. The APM suspensions described therein are less viscous, free flowing and are particularly suited for use in the dry, powdered beverage industry.

For purposes of the present disclosure, the term suspension refers to a system whereby very small particles (solid, semi-solid or liquid) are more or less uniformly dispersed in a different liquid or gaseous medium. If the particles are small enough to pass through a filter membrane, the system is colloi al. If the particles are larger than this, they will tend to precipitate and sink since they are heavier than the surrounding solution. Naturally, if they are lighter than the solution however, they will agglomerate and rise to the surface.

The suspension which serves as a starting point for the preparation of the sweetener compositions of the present invention is first prepared through the incorporation of a small amount of a water soluble flow agent such as food grade polymers, hydrocoUoids or gums into an aqueous aspartame solution. Suitable flow agents include, but are not limited to sodium carboxymethyl cellulose, algin, gum arable, carrageenan, xanthan gum, guar gum, hydroxypropyl methyl cellulose (HPMC) , methylcellulose, pectin, locust bean gum, sodium alginate, propylene glycol alginate, caramel and mixtures thereof. Trace amount of an emulsifier or wetting agent such as polysorbate (polyoxyethylene fatty acid ester) or lecithin may also be incorporated to improve the suspensions' dissolution and stability characteristics. The water soluble food grade polymers, hydrocoUoids, gums and mixtures thereof are incorporated into the aspartame aqueous suspension in amounts of from about 0.001% to about 0.5% by weight of the total weight of the suspension. Levels exceeding 0.5% will continue to reduce the viscosity of the suspension but this is not critical to the practice of the present invention and viscosity is reduced to a less effective degree than the lower levels.

When mixed in a suspension with the stabilizing flow agent, aspartame levels of from approximately 10% to about 70% by weight of the total weight of the suspension is achievable. Preferably, said aspartame is incorporated in amounts of from about 20% to about 55% by weight and most preferably in an amount of from about 20% to about 35% by weight of the entire suspension.

Although aspartame powder is sparingly soluble in water by itself, suspensions of up to 30% can be made. However, this pure aspartame/water suspension is a very viscous foam or paste which does not lend itself to most food and beverage processing operations. The addition of the polymers, hydrocoUoids or gums to the aqueous suspension of aspartame surprisingly alters the flow characteristics of the suspension to a more fluid form exhibiting pseudoplastic flow behavior with enhanced dissolution properties and stability.

Traditionally, hydrocoUoids have been used to increase the viscosity of fluids. In the present case however, the addition of the hydrocolloid turns the foam into fluid, the viscosity decreases, and the APM suspension becomes fluidized thereby becoming more manageable. Microscopy data shows that the APM crystals surround air bubbles in the foam and that the crystals are floating or moving freely in a liquid suspension. Without being bound to any theory, this phenomena may be explained by the fact that APM is a dipeptide with a hydrophobic group in its structure. When this is dissolved in water, the water becomes organized and further addition of the APM crystals creates the foam by the stabilized aspartame. Addition of a small amount of a very hydrophilic polymer like carrageenan or sodium carboxymethyl cellulose (sodium CMC) frees up the water and allows more APM to be added to the system. The aspartame/flow agent suspension is then combined with an aqueous solution of the encapsulation agent or agents. Suitable encapsulating agents are carbohydrates such as the dextrins, gum arable and starches. Specifically, maltodextrin with a low dextrose equivalent (DE) value of from about 5.0 to about 25.0 is preferred while maltodextrins with a DE value of from about 10.0 to about 15.0 are most preferred. Commercially available maltodextrins that are suitable in the practice of the present invention include the Maltrin^® series of maltodextrins (Grain Processing Corp., Muscatine, Iowa) .

Gum arabic and any number of food grade starches will also provide suitable encapsulation functionality. Whereas native starches provide little emulsification properties to spray dried flavors and sweeteners, there is a great deal of improvement when the starch is modified through esterification with a substituted cyclic dicarboxylic acid anhydride. Commercially available modified starches include N-Lok and Capsul, two modified waxy maize starches (National Starch,

Bridgewater, N.J.) and Amylogum CLS, a modified potato starch.

Hydrolyzed starches also perform well as the encapsulating agent. Suitable commercially available hydrolyzed starches include two lipophilic modified waxy corn starches, Sta-Mist 515 and Mira-Cap (Staley Inc., Decatur, 111.). Mixtures of these agents may also be employed and a commercially available mixture known as ARS is available which is a blend of dextrins, carageenans and dextrose. Another excellent blend is National 46, a combination of dextrin and a hydrolyzed starch. (Grain Processing Corp., Muscatine, Iowa). The use of gums with hydrolyzed starch for example, provides a better product than the hydrolyzed starch alone in many applications as the blend exhibits greater emulsification properties. In summary then, whatever encapsulation agent/agents is selected depends in part upon what flavor or sweetener is being encapsulated. In the case of the particulate aspartame sweetener, maltodextrin is most preferred.

The aqueous aspartame/flow agent suspension preferably comprises a 50% aspartame concentration and is mixed with the encapsulation agent solution thoroughly prior to drying. The amount of encapsulation agent dissolved in solution and mixed with the aspartame/flow agent suspension also depends upon the type of agent used and the application to which the finished encapsulated particulate product is employed. Generally, the specifications listed on the packaging or labeling for each respective encapsulation agent will provide additional guidance in this area. Preferably maltodextrin/APM weight ratios of from about 3:7 to 7:3 may be used, and more particularly ratios of 2:3 to 3:2 give best results. However, maltodextrin/aspartame ratios of 1:99 to about 5:95 respectively, are sufficient to stabilize the aspartame and prevent "balling" or "pilling" of the sweetener composition as is known in the art of blending dry, powdered ice tea and soft drink beverage compositions. When aspartame powder is gently mixed with dry ^~oods such as powdered coffee, tea etc. in a "V" type blender, the aspartame can segregate and form "pills" or "balls" and is not well distributed in the final product. This phenomenon occurs only in gentle blending operations when more attrition is used. In a ribbon blender, this does not occur. The addition of about 1.0% to 5.0% maltodextrin to the APM liquid suspension and subsequent spray drying of the mixture to a powder yields a product with flow properties that do not cause pill or ball formation in gentle mixing operations. Moreover, aspartame/maltodextrin/gum arabic mixtures in ratios of about 15:9:1 respectively, yield an encapsulated dry aspartame particle that exhibits particularly excellent flow properties. The encapsulated product may conceivably be made by any one of a number of the drying methodologies as is known in the art such as pan drying, spray drying, spheronized particle air flow drying and the like. Preferably, the APM suspension and coating solutions are mixed together and spray dried using a Niro spray drier or rotary atomizer apparatus.

Prior to spray drying the aspartame flow agent suspension with the encapsulation agent, the viscosity of the aqueous suspension should range from about 200- 1500 m.P.a. and preferably, 200-1000 m.P.a. at a shear of 1/100 sec. using a Haake Viscometer, (Haake Buchler Instruments Inc., Saddlebrook, N.J.). For optimized spray drying results, the aqueous suspension and the encapsulating agent should be combined in a well mixed solution wherein the solids comprise from about 20% to about 60% of the total mixture. This concentration range produces the optimum viscosity for atomization and efficient encapsulation. The temperature of the blend is also important as it has a direct effect on the viscosity of the feed suspension. Preferably, the feed solution should be maintained at a temperature of from about 60° to about 100°F and ideally from about 60° to 80°F.

The dry, stable, free flowing aspartame particles are particularly useful in powdered beverage compositions which are packaged and sold as a dry powder and subsequently prepared as an aqueous beverage by mixing a pre-determined amount in water. Powdered flavored coffees, teas, cocoa, fruit drinks and powdered dietary beverage formula are particularly improved through the use of this sweetener.

The following examples are provided to more specifically describe and set forth several contemplated embodiments of the present invention. They are for illustrative purposes only and it is understood that minor changes and alterations may be made to the parameters of the process or the ingredients used therein which are not specifically detailed. It is to be recognized that such changes which do not materially alter or affect the final product are still considered as falling within the spirit and scope of the invention as recited by the claims that follow. Example I

A number of aspartame (APM) liquid suspensions at 50% concentration were prepared using the stabilizing flow agents of the present invention comprising the following food polymers, hydrocoUoids and gums in an amount of approximately 0.2% -0.3% by weight of the total weight of the suspension. The flow curves of the suspensions were generated using the Haake Rotoviscometer Model VT500 at 25°C using a MV1 sensor. The viscosity at 54 1 /s is reported below.

Viscosity at Polymer Flow Agent 54 (1/s) shear rate 25°C

Carrageenan 32

Sodium Alginate 88 Xanthan gum 63

Sodium carboxymethyl cellulose 111

Locust bean gum 519

Guar gum 193

Pectin 1 51 2 Gum Arabic 679

Propylene glycol alginate 18

Caramel DS #400 1 66

A combination of polymer flow agents can also be used to make fluid 50% APM suspensions in water as shown below:

Viscosity at Polymer Flow Aσent 54 (1/s) shear rate 25°C

0.2% Carrageenan + 0.05% Xanthan 58 0.2% Carrageenan + 0.05% Locust bean gum 68

0.2% Carrageenan + Guar gum 43 0.2% Carrageenan + 0.05%

Sodium carboxymethyl cellulose 64

Samples of the above suspensions ( 50 ml . ) were placed in test tubes and spun in a table- top centrifuge for fifteen ( 1 5) minutes at 50 g. After this time, all suspensions exhibited less than 2.0% sedimentation in the tubes . Example II

Two stable, particulate sweetener compositions of the present invention were prepared as follows:

Sample A 4000 gms. liquid APM suspension (50% concentration)

-0.3% carboxymethylcellulose as the flow agent

Sample B

6000 gms. liquid APM suspension (50% concentration)

-3.0% carboxymethylcellulose as the flow agent

In two separate containers, 2000 and 3000 gms. of maltodextrin with a DE value of approximately 15 (Maltrin™ 100) were mixed in 2000 and 3000 gms. of distilled water respectively. The solutions were warmed to approximately 38°C and stirred until the maltodextrin was completely dissolved. Sample A was then added to the 2000 gms. maltodextrin solution while sample B was added to 3000 gms. solution, and both were stirred until uniform solutions were obtained. The mixture was then dried in a Niro spray drier equipped with a rotary atomizer. The inlet temperature is from approximately 150°C to about 200°C and outlet temperature is from approximately 90°C to about 110°C. The rotary atomizer wheel is at about 2000-5000 r.p.m. The mixture is atomized into fine droplets which are dried in the drier by air and the resulting powder consists of spherical particles in which APM is encapsulated by the maltodextrin. The powder is free flowing and is readily dissolved in water.

Claims (26)

ClaimsWhat We Claim is:

1. A shelf stable particulate sweetening composition comprising a core dipeptide sweetening agent and a stabilizing flow agent selected from the group consisting of sodium carboxymethyl cellulose, dextran, algin, gum arabic, carrageenan, xanthan gum, guar gum, hydroxy-propylmethyl cellulose, methyl cellulose, pectin, locust bean gum, sodium alginate, propylene glycol alginate, caramel and mixtures thereof in an amount of from about 0.001% to about 0.6% that has been encapsulated with a water soluble coating agent selected from the group consisting of maltodextrin, starch, gum arabic and mixtures thereof in coating agent:core weight ratios of from about 3:7 to about 7:3.

2. The sweetening composition of claim 1 wherein said dipeptide sweetening agent is α-L-aspartyl-L- phenylalanine methyl ester (aspartame) .

3. The sweetening composition of claim 2 wherein said core comprises a dried aqueous suspension of said dipeptide sweetening agent and said stabilizing flow agent.

4. The sweetening composition of claim 3 wherein said starch is selected from the group consisting of modified starches, hydrolyzed starches and mixtures thereof.

5. The sweetening composition of claim 4 wherein said starch is selected from the group consisting of hydrolyzed or modified corn starch, hydrolyzed or modified potato starch and mixtures thereof.

6. The shelf stable sweetener composition of claim 5 wherein said aspartame is present in an amount of from about 20% to about 55% by weight of the total weight of the suspension.

7. The shelf stable sweetener composition of claim 6 wherein said aspartame is present in an amount of from about 20% to about 35% by weight of the total weight of the suspension.

8. The sweetener composition of claim 7 wherein said flow agent is spray dried with said aspartame in weight ratios of from about 2:3 to about 3:2, respectively.

9. The shelf stable sweetener composition of claim 8 further comprising an emulsifier.

10. The shelf stable sweetener composition of claim 9 wherein said emulsifier is selected from the group consisting of polysorbate, lecithin and mixtures thereof.

11. A method for the preparation of a shelf stable, particulate sweetening composition comprising: a) suspending a high intensity dipeptide sweetening agent and a stabilizing flow agent selected from the group consisting of sodium carboxymethyl cellulose, dextran, algin, gum arabic, carrageenan. xanthan gum, guar gum, hydroxy- propylmethyl cellulose, methyl cellulose, pectin, locust bean gum, sodium alginate, propylene glycol alginate, caramel and mixtures thereof in an amount of from about 0.001% to about 0.6% in an aqueous solution to form a suspension; b) mixing said suspension with an aqueous solution of a water soluble encapsulation agent selected from the group consisting of maltodextrin, starch, gum arabic and mixtures thereof, and; c) drying said mixture to form free flowing encapsulated sweetener particles.

12. The method of claim 11 wherein said dipeptide sweetening agent is α-L-aspartyl-L-phenylalanine methyl ester (aspartame) .

13. The method of claim 12 wherein said starch is selected from the group comprising hydrolyzed or modified corn starch, hydrolyzed or modified potato starch and mixtures thereof.

14. The method of claim 13 wherein said mixture is dried by means of spray drying, pan drying, hot air spheronization and static heat.

15. The method of claim 14 wherein the viscosity of said mixture prior to drying is from about 200 to about 1000 m.P.a.

16. The method of claim 15 wherein said mixture is spray dried.

17. The method of claim 16 wherein said stabilizing polymer flow agent is present in an amount of from about 0.1% to about 0.3% by weight of the total weight of the suspension.

18. The method of claim 17 wherein said coating agent is spray dried with said suspension in weight ratios of from about 3:7 to 7:3, respectively.

19. The method of claim 18 wherein said coating agent is spray dried with said aspartame in weight ratios of from about 2:3 to about 3:2, respectively.

20. The method of claim 19 further comprising an emulsifier.

21. The method of claim 20 wherein said emulsifier is selected from the group consisting of polysorbate, lecithin and mixtures thereof.

22. A particulate sweetener composition comprising a core of aspartame and a food grade flow agent selected from the group consisting of sodium carboxymethyl cellulose, dextran, algin, gum arabic, carrageenan, xanthan gum, guar gum, hydroxy- propylmethyl cellulose, methyl cellulose, pectin, locust bean gum, sodium alginate, propylene glycol alginate, caramel and mixtures thereof in an amount of from about 0.001% to about 0.6% that has been encapsulated with a water soluble coating agent selected from the group consisting of maltodextrin, starch, gum arabic and mixtures thereof in coating agent:core weight ratios of from about 3:7 to about 7 : 3 .

23. The sweetener composition of claim 22 wherein said starch is selected from the group comprising modified starches, hydrolyzed starches and mixtures thereof.

24. The encapsulated particulate sweetening composition of claim 23 useful in dry powdered beverage mixes.

25. The encapsulated particulate sweetening composition of claim 24 wherein said beverage mixes are selected from the group comprising powdered flavored coffees, teas, cocoa, fruit drinks, dietary beverage formula and the like.

26. The encapsulated particulate sweetening composition of claim 25 useful in dry food applications.