Sweetener composition including enzymatically processed stevia and method of manufacturing

Abstract

A low-calorie sweetener composition, and method of manufacturing the same. The method includes providing a first sweetener having a mean particle size of between 100-350 m in diameter and coating the first sweetener with a second sweetener. The first sweetener is sucrose. The second sweetener is an enzymatically modified steviol glycoside. The sweetener composition optimally includes at least 95% table sugar and at least 1% steviol glycoside. The steviol glycoside having been modified by action of at least one enzyme, the enzyme being a fungal exoenzyme selected from the group consisting of: laccase, manganese-dependent peroxidase (MnP), lignin peroxidase (LiP), versatile peroxidase (VP), monooxygenase, and combinations thereof.

Claims

1. A method for producing a low-calorie sweetener composition comprising: a) providing a first sweetener including table sugar having a mean particle size of between 100-350 um in diameter; b) providing a second sweetener in an aqueous solution including at least one steviol glycoside that has been subject to enzymatic treatment by monooxygenase; c) coating the first sweetener with the second sweetener to yield a low-calorie sweetener composition; and d) drying the low-calorie sweetener composition to between 0.5-5% moisture content to yield a sweetener composition having less than 5 calories per serving.

2. The method as set forth in claim 1, wherein the coating thickness is between 1-20 um.

3. The method as set forth in claim 1, wherein the aqueous solution has a concentration of at least 5 tablespoons of steviol glycoside per liter of water to maintain flow ability of the aqueous solution.

4. The method as set forth in claim 3, wherein the steviol glycoside is modified by an enzyme complex including laccase, manganese-dependent peroxidase (MnP), lignin peroxidase (LiP), versatile peroxidase (VP), and monooxygenase.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a Stevioside molecule.

(2) FIG. 2 is a Rebaudioside A molecule.

(3) FIG. 3 is a method of making a composition in accordance with the present invention using an enzymatically modified steviol glycoside.

(4) FIG. 4 is a method of making a mixture in accordance with the present invention.

DETAILED DESCRIPTION

(5) The present invention includes a sweetener having less than 4-5 calories per serving. This is achieved by a novel process which coats granules of table sugar (sucrose) having a specified average granular size with an enzymatically treated stevia-based mixture. The stevia-based mixture includes at least some modified steviol glycosides. The steviol glycosides are enzymatically modified with either fungal exoenzymes or bacterial enzymes under controlled conditions.

(6) In one embodiment of the invention, the table sugar has a granule size having a mean particle size in the range of 100-600 m. Preferably the granule size has a mean particle size of 100-300 m, and more preferably the mean particle size is between 125-175 m. Ideally the mean particle size is 150 m. The mean particle size is calculated as the hypothetical mesh aperture of a sieve that allows 50% of the sugar to pass.

(7) The invention applies a coating to each granule in order to increase the sweetness of each granule to yield a sugar-stevia product that is 3-10 sweeter than sugar, and preferably closer to 5 the sweetness of sugar.

(8) The coating in one embodiment of the invention is approximately 1-10 m thick and fully coats each sugar granule. The coating in another embodiment of the invention is approximately 10-20 m thick and fully coats each sugar granule. The coating thickness varies with the purity and sweetness of the stevia mixture, and the size of the sugar granule.

(9) In an alternate embodiment, the table sugar granules are coated, having 90% (on average) of the granule surface area of the sugar covered by the coating.

(10) In one embodiment the composition is 92-99% table sugar granules. The table sugar granules are dry, having a moisture content of less than 10%, preferably less than 5%, and more preferably within the range of 0.5-3%.

(11) Table sugar is defined herein to include a mixture of glucose, fructose, dextrose, sucrose, or any combination thereof. Table sugar can be made from sugar cane, beets, or other plants. Preferably, the table sugar is has an approximate 50/50 ratio of glucose and fructose. It can be appreciated that this ratio can vary to include any ratio that enables commercial scale distribution of the table sugar.

(12) The table sugar granules are coated with a stevia mixture, particularly a steviol glycoside solution.

(13) The composition of the present invention is dry (having less than 10% moisture content). Hydration of this composition is enabled by mixing with water. The dry composition includes 1%-8% of dry steviol glycoside and 92%-99% table sugar, by volume. Accordingly, where the steviol glycoside solution coats the sugar granules, and where the sugar granules have a granular diameter of 100-300 m, whereby the composition is 4-6 times sweeter than table sugar. In this way, one serving of the composition has approximately 75%-85% less calories than table sugar per serving. Presumably, the glycemic response to the composition is reduced in proportion to the lesser volume of sugar calories.

(14) In another embodiment the composition is 97-99% sugar and 1-3% steviol glycoside solution, by volume. Preferably, the steviol glycoside solution comprises 90-98% purity Reb A in an aqueous solution. More preferably the steviol glycoside solution comprises 95-98% purity Reb A in an aqueous solution.

(15) In alternate embodiments, the aqueous solution further contains sucrose and dextrose along with the steviol glycoside. After the steviol glycoside solution is applied to the sugar granules, the composition is dried to the desired moisture content, for example a 3-5% moisture content.

(16) Utilizing an aqueous solution for applying the steviol glycoside coating assures maximization of the area covering the table sugar granules. Optimally the steviol glycoside coating is uniformly distributed on the table sugar granules.

(17) The combination of a portion of table sugar to the steviol glycoside may improve coating integrity and adhesion of the steviol glycoside solution to the table sugar granules when applied and dried.

(18) Preparation of the steviol glycoside solution includes heating the steviol glycoside solution to fully dissolve the portion of sugar and the stevia glycoside to make the steviol glycoside solution. In one embodiment, the steviol glycoside solutions is heated to 78-107 C. for a period of about 8-20 minutes to enable preparation of the steviol glycoside solution.

(19) Applying the steviol glycoside solution is accomplished in accordance with one aspect of the invention by a fluid bed coating system that circulates heated air in a chamber to agitate the sugar granules, and simultaneously heats and sprays the steviol glycoside solution from the bottom of the chamber to uniformly coat the sugar granules. Heating the steviol glycoside solution enables optimal viscosity of the solution as well as adherence of the solution to the granules.

(20) Drying the granules after application of the steviol glycoside solution is accomplished in a separate fluid bed drying apparatus, or in the same the fluid bed coating system, which is adapted to perform a drying function.

(21) Calculating the volume of the coating can utilize the formula:

(22) $\frac{4}{3}{\left(r_1+r_2\right)}^3-\frac{4}{3}{r}_1^3=V_c$
where r.sub.1 is the radius of the sugar granule and r.sub.2 is the radius of the coated granule, and V.sub.c is the volume of the coating. Accordingly thickness of the coating (or range thereof) can be determined for any granule size, knowing the desired volumetric ratio of the sugar/stevia glycoside ratio.

Manufacturing Method

(23) A method for producing a low-calorie sweetener composition that has no fillers, and has less than 5 calories per serving, and virtually no flavor defects includes:

(24) a) providing a first sweetener including table sugar having a mean particle size of between 100-350 m in diameter;

(25) b) providing a second sweetener in an aqueous solution including at least one steviol glycoside that is modified by either fungal exoenzymatic action or by action of bacterial derived enzymes;

(26) c) heating the second sweetener to above 78 C. and pressurizing the second sweetener in a pressure vessel at above 1 atm of pressure to enable atomization;

(27) e) agitating the first sweetener solids in a fluid bed processor;

(28) f) coating the first sweetener with the second sweetener by spraying in an upward direction to yield a low-calorie sweetener composition;

(29) g) drying the low-calorie sweetener composition to between 0.5-10% moisture content to yield a sweetener composition having less than 5 calories per serving and each serving having a sweetness of a serving of sucrose.

(30) The method includes establishing an atomization pressure between 14.7 psi-50 psi, and preferably 25 psi atomizing air pressure and 15 psig liquid pressure in a fluid bed processor. The method of spray can be top spray, or bottom spray or both. Preferably top spray is used. Excipient distributions are variable depending on granular size of sugar granules, and the desired caloric content of the product.

(31) Testing conducted utilized a range from 2-4 tablespoons of Rebaudioside A having a 98% purity (RA98), which was distributed over approximately 7-8 pounds of table sugar. The Rebaudioside A is dissolved in water at a concentration of 5 Tbsp/liter in order to achieve a viscosity optimal for spraying. No fillers or salts are added in this embodiment of the invention.

(32) In general, Rebaudioside A having at least a 98% purity (RA98) tends to create suspended solids in solution with water, as opposed to lower grades which readily dissolve. The effective viscosity of the steviol glycoside solution, particularly the RA98 mixture, creates a unique problem because the spray is viscous. Little of the steviol glycoside solution is needed relative to other coating technologies because of the intense sweetening capabilities of RA98. Accordingly the RA98 steviol glycoside solution is diluted to five (5) table spoons per liter of water. The substrate mixing that occurs on a fluid bed spread the spray evenly and provides for good particle-to-particle transfer of the coating, while the heated air dries away water and prevents the product from dissolving or clumping.

(33) FIG. 3 is a method 10 of enzymatic treatment of stevia in accordance with the present invention. The method 10 includes the step 12 of providing an enzymatically glycosylated steviol glycoside such as Rebaudioside A having a 90% or greater purity and mixing it in purified water. Preferably, the Rebaudioside A has a purity of greater than 97%.

(34) The method 10 includes the step 14 of coating a sugar granule having a mean diameter of between 100-300 m with the glycosylated stevia glycoside. The coating is only a fraction of the sugar granule mean diameter, or 5-20 m to minimize segregation of the sugar granules. All of the sugar granules are coated in one embodiment of the invention. In an alternate embodiment a portion are coated and mixed with sugar granules that are uncoated. Coating can be a partial coating on the sugar granules or a complete coating of the sugar granules. The composition has between 1-3% steviol glycoside on a dry weight basis, and between 97-100% sucrose on a dry weight basis.

(35) FIG. 4 shows a method generally designated with the reference numeral 16. The method 16 includes the step 18 of providing an enzymatically glycosylated stevia glycoside such as Rebaudioside A having a 90% or greater purity in granular form. The method 16 also includes the step 20 of mixing sugar granules having a mean diameter of between 100-300 m with the glycosylated stevia glycoside having the same mean diameter as the sugar granules. The same as used in this paragraph means a diameter sufficient to effective eliminate segregation of the sugar granules and stevia granules during normal handling of the mixture. In one embodiment the diameter of the coated sugar granules have a mean diameter that does not exceed the mean diameter of the uncoated sugar granules by more than 10%

(36) Various examples of the sweetener compositions in accordance with the present invention are provided by way of example, but not limiting of the scope of the present invention.

Example 1

(37) A sweetener composition that is about five time sweeter than sugar uses a 95% or greater purity Rebaudioside A coating over granular sugar, where the sugar content 97-98.5%, and the Rebaudioside A content is 1.5-3% by volume. The granular sugar has a mean particle size of between 100-300 m, and less than 5 calories per serving. The Rebaudioside A is modified by enzymatic glycosylation to virtually eliminate any bitter aftertaste, and other flavor defects.

Example 2

(38) A sweetener composition that is about four time sweeter than sugar uses a 98% or greater purity Rebaudioside A coating over granular table sugar, where the sugar content 98-99%, and the Rebaudioside A content is 1-2% by volume. The granular sugar has a mean particle size of between 100-150 m, and between 4-5 calories per serving. The Rebaudioside A has been modified by enzymes to minimize perceived flavor defects.

Example 3

(39) A sweetener composition that is about five times sweeter than sugar uses a stevioside coating over granular sugar, where the sugar content is 92-94%, and has a steviol glycoside content of 6-8% by volume, and less than 5 calories per serving. The coating is less than 20 m in thickness. The steviol glycoside being modified by enzymatic glycosylation to virtually eliminate any bitter aftertaste, and other flavor defects.

Example 4

(40) A sweetener composition uses a 98% or greater purity Rebaudioside A coating over granular table sugar, where the sugar content 98-99%, and the Rebaudioside A content is 1-2% by volume. The granular sugar has a mean particle size of between 100-300 m, and less than 5 calories per serving. The Rebaudioside A being enzymatically modified by a mix of polypore mushroom enzymes to minimize perceived flavor defects. The sweetener composition has between 2.5-3.5 calories per serving.

(41) While the above examples and the specification of this patent application are exemplary in nature, the true scope of the invention is defined by the appended claims. It can be appreciated that the mechanism of action of modifying the steviol glycoside is, in one embodiment of the invention, by the addition of fungal metabolites created by action of an enzyme complex on the steviol glycoside, where the enzyme complex includes one or more of laccase, manganese-dependent peroxidase (MnP), lignin peroxidase (LiP), versatile peroxidase (VP), monooxygenase, and combinations thereof. In another embodiment, the action of these enzymes directly modifies the steviol glycoside molecule, particularly its isoforms.