Stevia composition

Abstract

Stevia compositions are prepared from steviol glycosides of Stevia rebaudiana Bertoni. The compositions are able to provide a superior taste profile and can be used as sweetness enhancers, flavor enhancers and sweeteners in foods, beverages, cosmetics and pharmaceuticals.

Claims

1. A stevia composition comprising a carboxylate salt of rebaudioside B, made by a process comprising the steps of: providing a stevia sweetener; providing an alkaline aqueous solution; dispersing the stevia sweetener in the alkaline solution and incubating for about 12 to 48 hours at about 55-75° C. to form a mixture; cooling the mixture to about 10-30° C. and adjusting the pH with acid to about pH 3.0-4.0; incubating the mixture to obtain a precipitate; separating the precipitate and washing it with water; drying the washed precipitate to obtain the stevia composition; dispersing the stevia composition in water to form a mixture; adding a base corresponding to the carboxylate salt into the mixture to achieve a pH level of 6.5 to 14.0; incubating the mixture for 0.1 to 24 hours to facilitate conversion of a rebaudioside B into the carboxylate salt of rebaudioside B; and separating and drying the stevia composition comprising the carboxylate salt of rebaudioside B.

2. The stevia composition of claim 1, the composition comprising a mixture of rebaudioside A, and rebaudioside B, and rebaudioside B carboxylate salt, wherein the ratio of rebaudioside A to rebaudioside B and rebaudioside B carboxylate salt ranges from about 5%:95% to about 95%:5% (w/w).

3. The stevia composition of claim 1, the composition comprising a mixture of rebaudioside D, rebaudioside B, and rebaudioside B carboxylate salt, wherein the ratio of rebaudioside D to rebaudioside B and rebaudioside B carboxylate salt ranges from about 5%:95% to about 95%:5% (w/w).

4. A food, beverage, pharmaceutical or cosmetic composition comprising the stevia composition of claim 1.

5. The stevia composition of claim 1, wherein the process of making comprises before the step of dispersing the stevia composition in water to form a mixture the further steps of: suspending the stevia composition in water and incubating at an elevated temperature for about 1-3 hours, wherein the elevated temperature is a temperature of about 50 to 100° C.; separating the stevia composition from the water and drying the stevia composition to obtain a purified stevia composition; wherein the purified stevia composition comprises rebaudioside B with greater than about 99% purity.

6. The stevia composition of claim 1, wherein the process of making comprises the further steps of: suspending the stevia composition comprising the carboxylate salt of rebaudioside B in water to form a suspension; increasing the temperature by a gradient heating method; holding the suspension at an elevated temperature, wherein the elevated temperature is a temperature of 110 to 140° C.; decreasing the temperature of the suspension to room temperature by a gradient cooling method to obtain a stevia composition solution; and spray drying the stevia composition solution to provide a stevia composition comprising the carboxylate salt of rebaudioside B with a solubility in water at 25° C. of about 2.5% (w/v).

7. The stevia composition of claim 6, wherein the gradient of the gradient heating and/or gradient cooling method is 1° C. per minute.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings are included to provide a further understanding of the invention. The drawings illustrate embodiments of the invention and together with the description serve to explain the principles of the embodiments of the invention.

(2) FIG. 1 shows the chemical structure of rebaudioside A.

(3) FIG. 2 shows the chemical structure of rebaudioside B

(4) FIG. 3 shows an HPLC chromatogram of a stevia composition comprising rebaudioside A and rebaudioside B.

DETAILED DESCRIPTION OF THE INVENTION

(5) Advantages of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

(6) Rebaudioside A commercialized by PureCircle Sdn. Bhd. (Malaysia), containing, rebaudioside A (about 95-100%), stevioside (about 0-1%), rebaudioside C (about 0-1%), rebaudioside D (about 0-1%), rebaudioside F (about 0-1%), rebaudioside B (about 0.1-0.8%) and other glycosides amounting to total steviol glycosides' content of at least about 95%, may be used as a starting material. Alternatively stevia extracts with different ratios of steviol glycosides may be used as starting materials.

(7) The HPLC analysis of the raw materials and products can be performed on an Agilent Technologies 1200 Series (USA) liquid chromatograph, equipped with Phenomenex Prodigy ODS3, 5 (4.6×250 mm) column at 40° C. The mobile phase was 32:68 mixture of acetonitrile and 10 mmol/L sodium phosphate buffer (about pH 2.6) at 1 mL/min. A diode array detector set at 210 nm can be used as the detector. One example of an HPLC chromatogram thus obtained is shown in FIG. 3.

(8) As used herein, unless specified further, “reb B” and “reb B composition” shall be used interchangeably to refer to purified rebaudioside B or rebaudioside B in combination with any other chemical entity.

(9) Preparation of Reb B

(10) 1. Alkaline Conversion

(11) One way to obtain reb B starting with reb A is described as follows. Reb A is dispersed in aqueous alkaline solution. The concentration of reb A is about 0-50% (w/v) preferably about 10-25%. The preferred alkaline agents include potassium hydroxide and sodium hydroxide, however other agents capable of increasing the pH of the media above about pH 7 may be used as well or alternatively. The concentration of alkaline agents is about 0.05-2.0M, preferably about 0.1-1.0M. The mixture is incubated at about 10-150° C., preferably about 30-100° C., for a period of about 0.5-48 hrs, preferably about 1-24 hrs. As a result, reb A is hydrolyzed to reb B. The molar yield of conversion of reb B is about 5-100%, preferably about 10-90%.

(12) After the reaction, the alkaline agent is neutralized by an acid, preferably by sulfuric acid or ortho-phosphoric acid until a pH of about 3.0-5.0 is reached, preferably until a pH of about 3.0-4.0 is reached. Upon neutralization, a precipitate is formed. The precipitate is separated by any method known in the art such as filtration or centrifugation and washed with water until the water reaches a pH of about 4.0-5.0. The obtained crystalline material is dried under vacuum at about 60-105° C. to yield a mixture of reb A and reb B having a ratio of about 5%:95% to about 95%:5% (w/w), preferably about 50%:50% to about 90%:10% (w/w).

(13) 2. Optional Post-Conversion Purification

(14) To obtain purified reb B, in one embodiment the separated precipitate described above is suspended in water and the mixture is subjected to continuous agitation over about 0.5-24 hrs, preferably about 1-3 hours, at about 50-100° C., preferably about 60-80° C. The ratio of precipitate to water (w/v) is about 1:5 to about 1:20, preferably about 1:10 to about 1:15. The washed crystals are separated and dried under vacuum at about 60-105° C. to yield reb B with about 99% purity.

(15) 3. Optional Post-Conversion Solubility Enhancement

(16) The following procedure can be used to increase the water solubility of reb B or any reb B composition. The obtained compositions generally have a water solubility of less than about 0.2% (w/v). In order to increase the solubility of these compositions, the reb B composition is combined with the water at ratio of about 1:1 (w/w) and the obtained mixture is subjected to a gradient heat treatment which results in a high stability and high concentration solution. The gradient of about 1° C. per minute is used in heating the mixture. The mixture is heated to the temperature of about 110-140° C., preferably about 118-125° C. and is held at maximum temperature for about 0-120 min, preferably about 50-70 min. After the heat treatment, the solution is cooled down to room temperature at gradient of about 1° C. per minute. The solution is spray dried by a laboratory spray drier operating at about 175° C. inlet and about 100° C. outlet temperatures. An amorphous form of the composition is obtained with greater than about 20% solubility in water at room temperature.

(17) Preparation of Reb B Salt

(18) Reb B obtained using the processes described above, or any other process, can be fully or partially converted into a carboxylate salt form. Reb B, or a composition containing reb B, preferably reb B with a purity greater than 90% (w/w), is dispersed in the water to make an aqueous dispersion with 5-50% (w/v), preferably 5-15% solids content. Excess base is added to achieve a pH level of 6.5-14.0, preferably 8.5-11.0. The obtained mixture is incubated for 0.1-24 hrs, preferably 1-3 hrs. Then the suspended solids are separated by filtration and washed with water until neutral pH of the washing water is achieved. Alternatively other reactions able to convert reb B into a carboxylate salt form may be used. The preferred cations are K.sup.+ and Na.sup.+, and the respective bases—KOH and NaOH—are used. However other carboxylate salts of reb B can be prepared in a similar manner by using the base corresponding to the desired carboxylate salt.

(19) The obtained reb B carboxylate salt can be further purified and its solubility enhanced as described above.

(20) While not intending to be bound by theory, it is believed that any steviol glycoside having a carboxyl group can be converted into its carboxylate salt form for improving the taste and/or sweetness profile of the molecule. Another example of a steviol glycoside containing a carboxyl group is steviolbioside.

(21) Use of Reb B Carboxylate Salt

(22) The reb B carboxylate salt described above can be used as a sweetness enhancer, a flavor enhancer and/or a sweetener in various food and beverage products. Non-limiting examples of food and beverage products include carbonated soft drinks, ready to drink beverages, energy drinks, isotonic drinks, low-calorie drinks, zero-calorie drinks, sports drinks, teas, fruit and vegetable juices, juice drinks, dairy drinks, yoghurt drinks, alcohol beverages, powdered beverages, bakery products, cookies, biscuits, baking mixes, cereals, confectioneries, candies, toffees, chewing gum, dairy products, flavored milk, yoghurts, flavored yoghurts, cultured milk, soy sauce and other soy base products, salad dressings, mayonnaise, vinegar, frozen-desserts, meat products, fish-meat products, bottled and canned foods, tabletop sweeteners, fruits and vegetables.

(23) Additionally the reb B carboxylate salt compositions can be used in drug or pharmaceutical preparations and cosmetics, including but not limited to toothpaste, mouthwash, cough syrup, chewable tablets, lozenges, vitamin preparations, and the like.

(24) The compositions can be used “as-is” or in combination with other sweeteners, flavors and food ingredients.

(25) Non-limiting examples of sweeteners include steviol glycosides, stevioside, rebaudioside A, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside E, rebaudioside F, dulcoside A, steviolbioside, rubusoside, as well as other steviol glycosides found in Stevia rebaudiana Bertoni plant and mixtures thereof, stevia extract, Luo Han Guo extract, mogrosides, high-fructose corn syrup, corn syrup, invert sugar, fructooligosaccharides, inulin, inulooligosaccharides, coupling sugar, maltooligosaccharides, maltodextins, corn syrup solids, glucose, maltose, sucrose, lactose, aspartame, saccharin, sucralose, sugar alcohols.

(26) Non-limiting examples of flavors include lemon, orange, fruit, banana, grape, pear, pineapple, bitter almond, cola, cinnamon, sugar, cotton candy, vanilla flavors.

(27) Non-limiting examples of other food ingredients include flavors, acidulants, organic and amino acids, coloring agents, bulking agents, modified starches, gums, texturizers, preservatives, antioxidants, emulsifiers, stabilisers, thickeners, gelling agents.

(28) The following examples illustrate various embodiments of the invention. It will be understood that the invention is not limited to the materials, proportions, conditions and procedures set forth in the examples, which are only illustrative.

Example 1 Preparation of Stevia Composition

(29) 100 g of rebaudioside A produced by PureCircle Sdn. Bhd. (Malaysia), containing, 98.1% rebaudioside A, 0.3% stevioside, 0.2 rebaudioside C, 0.2% rebaudioside F, 0.4% rebaudioside B and 0.6% rebaudioside D was dispersed in 1000 mL aqueous KOH (1M) and incubated at 50° C. for 2 hours. The mixture temperature was decreased to 20° C. and the pH was adjusted to pH 4.0 with sulfuric acid. The solution was held under moderate agitation conditions for 4 hours and a precipitate was formed. The precipitate was filtered and washed on the filter with 2000 mL of water. The washed crystals were dried under vacuum to yield 86 g material containing about 84% reb A and 16% reb B. The water solubility (at 25° C.) of obtained material was about 0.2% (w/v).

Example 2 Preparation of Stevia Composition

(30) 100 g of rebaudioside A produced by PureCircle Sdn. Bhd. (Malaysia), containing, 98.1% rebaudioside A, 0.3% stevioside, 0.2 rebaudioside C, 0.2% rebaudioside F, 0.4% rebaudioside B and 0.6% rebaudioside D was dispersed in 1000 mL aqueous KOH (1M) and incubated at 80° C. for 5 hours. The mixture temperature was decreased to 20° C. and the pH was adjusted to about pH 4.0 with sulfuric acid. The solution was held under moderate agitation conditions for 4 hours and a precipitate was formed. The precipitate was filtered and washed on the filter with 2000 mL of water. The washed crystals were dried under vacuum to yield about 75 g material containing about 9% reb A and about 91% reb B. The water solubility (at 25° C.) of obtained material was about 0.1% (w/v).

Example 3 Preparation of Stevia Composition

(31) 100 g of rebaudioside A produced by PureCircle Sdn. Bhd. (Malaysia), containing, 98.1% rebaudioside A, 0.3% stevioside, 0.2 rebaudioside C, 0.2% rebaudioside F, 0.4% rebaudioside B and 0.6% rebaudioside D was dispersed in 1000 mL aqueous KOH (1M) and incubated at 80° C. for 7 hours. The mixture temperature was decreased to 20° C. and the pH was adjusted to about pH 4.0 with sulfuric acid. The solution was held under moderate agitation conditions for 3-4 hours and a precipitate was formed. The precipitate was filtered and washed on the filter with 2000 mL of water. The washed crystals were dried under vacuum to yield about 71 g material containing about 99.1% reb B. The water solubility (at 25° C.) of obtained material was about 0.1% (w/v).

Example 4 Preparation of Reb B

(32) 75 g of material prepared according to EXAMPLE 2 was suspended in 1000 mL water. The mixture temperature was increased to 70° C. The suspension was held under moderate agitation conditions for 4 hours. The crystals were filtered and dried under vacuum to yield about 65 g material containing about 99.0% reb B. The water solubility (at 25° C.) of obtained material was about 0.1% (w/v).

Example 5 Preparation of Reb B Carboxylate Salt

(33) 100 g of reb B prepared according to EXAMPLE 4 was suspended in 1000 mL water. The suspension was held under moderate agitation conditions at room temperature for 1 hr. The pH of the mixture was adjusted to pH 11.0 with 1M KOH solution. The obtained mixture was agitated for 3 hrs. The crystals were filtered and washed with water on the filter until the washing water reached a neutral pH. The obtained crystalline material was dried under vacuum to yield about 95 g material. The water solubility (at 25° C.) of obtained material was about 0.1% (w/v).

Example 6 Preparation of Soluble Stevia Composition

(34) 50 g material prepared according to EXAMPLE 1 was mixed with 50 g of water and incubated in thermostated oil bath. The temperature was increased at 1° C. per minute to 121° C. The mixture was maintained at 121° C. for 1 hour and then the temperature was decreased to room temperature (25° C.) at 1° C. per minute. The solution was dried using YC-015 laboratory spray drier (Shanghai Pilotech Instrument & Equipment Co. Ltd., China) operating at 175° C. inlet and 100° C. outlet temperature. About 47 g of an amorphous powder was obtained with about 25% (w/v) solubility in water (at 25° C.).

Example 7 Preparation of Soluble Stevia Composition

(35) 42 g of reb A produced by PureCircle Sdn. Bhd. (Malaysia) with purity of 99.2% (dry basis) and 8 g of reb B prepared according to EXAMPLE 4 were mixed with 50 g of water and incubated in thermostated oil bath. The temperature was increased at 1° C. per minute to 121° C. The mixture was maintained at 121° C. for 1 hour and then the temperature was decreased to room temperature (25° C.) at 1° C. per minute. The solution was dried using YC-015 laboratory spray drier (Shanghai Pilotech Instrument & Equipment Co. Ltd., China) operating at 175° C. inlet and 100° C. outlet temperature. About 48 g of an amorphous powder was obtained with about 1.5% (w/v) solubility in water (at 25° C.).

Example 8 Preparation of Soluble Stevia Composition

(36) 42 g of reb A produced by PureCircle Sdn. Bhd. (Malaysia) with purity of 99.2% (dry basis) and 8 g of reb B potassium salt prepared according to EXAMPLE 5 were mixed with 50 g of water and incubated in thermostated oil bath. The temperature was increased at 1° C. per minute to 121° C. The mixture was maintained at 121° C. for 1 hour and then the temperature was decreased to room temperature (25° C.) at 1° C. per minute. The solution was dried using YC-015 laboratory spray drier (Shanghai Pilotech Instrument & Equipment Co. Ltd., China) operating at 175° C. inlet and 100° C. outlet temperature. About 49 g of an amorphous powder was obtained with about 2.5% (w/v) solubility in water (at 25° C.).

Example 9 Low-Calorie Orange Juice Drink

(37) Orange concentrate (35%), citric acid (0.35%), ascorbic acid (0.05%), orange red color (0.01%), orange flavor (0.20%), and 0.05% stevia composition, were blended and dissolved completely in water (up to 100%) and pasteurized. The stevia composition was selected from a commercial stevia extract (containing stevioside 26%, rebaudioside A 55%, and 16% of other glycosides), a commercial rebaudioside A (containing 98.2% reb A) or material obtained according to EXAMPLE 7 and EXAMPLE 8.

(38) The sensory evaluations of the samples are summarized in Table 1. The data show that the best results can be obtained by using the composition obtained according to EXAMPLE 8. Particularly the drinks prepared with said composition exhibited a rounded and complete flavor profile and mouthfeel.

(39) TABLE-US-00001 TABLE 1 Evaluation of orange juice drink samples Comments Sample Flavor Aftertaste Mouthfeel Stevia Extract Sweet, licorice notes Bitterness and Not aftertaste acceptable Reb A Sweet, slight licorice Slight bitterness Not notes and aftertaste acceptable EXAMPLE 7 High quality sweetness, Clean, almost Full pleasant taste almost no bitterness similar to sucrose, and slight fairy rounded and aftertaste balanced flavor EXAMPLE 8 High quality sweetness, Clean, no Full pleasant taste similar bitterness and to sucrose, rounded no aftertaste and balanced flavor

(40) The same method can be used to prepare juices and juice drinks from other fruits, such as apples, lemons, apricots, cherries, pineapples, mangoes, etc.

Example 10 Zero-Calorie Carbonated Beverage

(41) Carbonated beverages made according to the formulas presented in Table 2 were prepared.

(42) TABLE-US-00002 TABLE 2 Carbonated Beverage Formulas Quantity, % Stevia Ingredients Extract Reb A EXAMPLE 7 EXAMPLE 8 Cola flavor 0.340 0.340 0.340 0.340 ortho-Phosphoric 0.100 0.100 0.100 0.100 acid Sodium citrate 0.310 0.310 0.310 0.310 Sodium benzoate 0.018 0.018 0.018 0.018 Citric acid 0.018 0.018 0.018 0.018 Stevia composition 0.050 0.050 0.050 0.050 Carbonated water to 100 to 100 to 100 to 100

(43) The sensory properties were evaluated by 20 panelists. The results are summarized in Table 3.

(44) TABLE-US-00003 TABLE 3 Evaluation of zero-calorie carbonated beverage samples Number of panelists detected the attribute Stevia Taste attribute Extract Reb A EXAMPLE 7 EXAMPLE 8 Bitter taste 15 10 2 0 Astringent 16  9 1 0 taste Aftertaste 14 12 2 0 Comments Quality of Bitter Bitter Clean Clean sweet taste aftertaste aftertaste (17 of 20) (20 of 20) (15 of 20) (10 of 20) Overall Satisfactory Satisfactory Satisfactory Satisfactory evaluation (1 of 20) (5 of 20) (16 of 20) (20 of 20)

(45) The above results show that the beverages prepared using the composition obtained according to EXAMPLE 8 possessed the best organoleptic characteristics.

Example 11 Diet Cookies

(46) Flour (50.0%), margarine (30.0%) fructose (10.0%), maltitol (8.0%), whole milk (1.0%), salt (0.2%), baking powder (0.15%), vanillin (0.1%) and different stevia compositions (0.03%) were kneaded well in dough-mixing machine. The obtained dough was molded and baked in oven at 200° C. for 15 minutes. The stevia compositions were selected from a commercial stevia extract (containing stevioside 26%, rebaudioside A 55%, and 16% of other glycosides), a commercial rebaudioside A (containing 98.2% reb A) and material obtained according to obtained according to EXAMPLE 7 and EXAMPLE 8.

(47) The sensory properties were evaluated by 20 panelists. The best results were obtained in samples containing the composition obtained according to EXAMPLE 8. The panelists noted a rounded and complete flavor profile and mouthfeel.

Example 12 Yoghurt

(48) Different stevia compositions (0.03%) and sucrose (4%) were dissolved in low fat milk. The stevia compositions were selected from a commercial stevia extract (containing stevioside 26%, rebaudioside A 55%, and 16% of other glycosides), a commercial rebaudioside A (containing 98.2% reb A) and the material obtained according to EXAMPLE 7 and EXAMPLE 8. After pasteurizing at 82° C. for 20 minutes, the milk was cooled to 37° C. A starter culture (3%) was added and the mixture was incubated at 37° C. for 6 hours then at 5° C. for 12 hours.

(49) The sensory properties were evaluated by 20 panelists. The best results were obtained in samples containing the composition obtained according to EXAMPLE 8. The panelists noted a rounded and complete flavor profile and mouthfeel.

(50) It is to be understood that the foregoing descriptions and specific embodiments shown herein are merely illustrative of the best mode of the invention and the principles thereof, and that modifications and additions may be easily made by those skilled in the art without departing for the spirit and scope of the invention, which is therefore understood to be limited only by the scope of the appended claims.