Glucosyl stevia composition

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a process for producing a highly purified food ingredient from the extract of the Stevia rebaudiana Bertoni plant and its use in various food products and beverages.

Description of the Related Art

Nowadays sugar alternatives are receiving increasing attention due to awareness of many diseases in conjunction with consumption of high-sugar foods and beverages. However many artificial sweeteners such as dulcin, sodium cyclamate and saccharin were banned or restricted in some countries due to concerns on their safety. Therefore non-caloric sweeteners of natural origin are becoming increasingly popular. The sweet herb Stevia rebaudiana Bertoni, produces a number of diterpene glycosides which feature high intensity sweetness and sensory properties superior to those of many other high potency sweeteners.

The above-mentioned sweet glycosides, have a common aglycon, steviol, and differ by the number and type of carbohydrate residues at the C13 and C19 positions. The leaves of Stevia are able to accumulate up to 10-20% (on dry weight basis) steviol glycosides. The major glycosides found in Stevia leaves are Rebaudioside A (2-10%), Stevioside (2-10%), and Rebaudioside C (1-2%). Other glycosides such as Rebaudioside B, D, E, and F, Steviolbioside and Rubusoside are found at much lower levels (approx. 0-0.2%).

Two major glycosides--Stevioside and Rebaudioside A, were extensively studied and characterized in terms of their suitability as commercial high intensity sweeteners. Stability studies in carbonated beverages confirmed their heat and pH stability (Chang S. S., Cook, J. M. (1983) Stability studies of stevioside and Rebaudioside A in carbonated beverages. J. Agric. Food Chem. 31: 409-412.)

Steviol glycosides differ from each other not only by molecular structure, but also by their taste properties. Usually stevioside is found to be 110-270 times sweeter than sucrose, Rebaudioside A between 150 and 320 times, and Rebaudioside C between 40-60 times sweeter than sucrose. Dulcoside A is 30 times sweeter than sucrose. Rebaudioside A has the least astringent, the least bitter, and the least persistent aftertaste thus possessing the most favorable sensory attributes in major steviol glycosides (Tanaka O. (1987) Improvement of taste of natural sweeteners. Pure Appl. Chem. 69:675-683; Phillips K. C. (1989) Stevia: steps in developing a new sweetener. In: Grenby T. H. ed. Developments in sweeteners, vol. 3. Elsevier Applied Science, London. 1-43.)

Methods for the extraction and purification of sweet glycosides from the Stevia rebaudiana plant using water or organic solvents are described in, for example, U.S. Pat. Nos. 4,361,697; 4,082,858; 4,892,938; 5,972,120; 5,962,678; 7,838,044 and 7,862,845.

However, even in a highly purified state, steviol glycosides still possess undesirable taste attributes such as bitterness, sweet aftertaste, licorice flavor, etc. One of the main obstacles for the successful commercialization of stevia sweeteners are these undesirable taste attributes. It was shown that these flavor notes become more prominent as the concentration of steviol glycosides increases (Prakash I., DuBois G. E., Clos J. F., Wilkens K. L., Fosdick L. E. (2008) Development of rebiana, a natural, non-caloric sweetener. Food Chem. Toxicol., 46, S75-S82.)

On the other hand, replacing large amounts of sugar in the formulations brings up such problems as reduced mouthfeel, incomplete flavor profile etc. Therefore the application of high intensity low calorie sweeteners has to provide solutions to address these problems.

Thus, if a single composition will be able to deliver not only sweetness, but also possess flavor enhancing properties and correct the incomplete mouthfeel associated with the elimination of sucrose from food and beverage formulations, it will certainly be advantageous compared to other high intensity sweeteners known in the art.

Some of these undesirable properties can be reduced or eliminated by subjecting steviol glycosides to the reaction of intermolecular transglycosylation, when new carbohydrate residues are attached to initial molecule at C13 and C19 positions. Depending on the number of carbohydrate residues in these positions the quality and potency of the compounds taste will vary.

Pullulanase, isomaltase (Lobov S. V., Jasai R., Ohtani K., Tanaka O. Yamasaki K. (1991) Enzymatic production of sweet stevioside derivatives: transglycosylation by glucosidases. Agric. Biol. Chem. 55: 2959-2965), .beta.-galactosidase (Kitahata S., Ishikawa S., Miyata T., Tanaka O. (1989) Production of rubusoside derivatives by transglycosylation of various .beta.-galactosidase. Agric. Biol. Chem. 53: 2923-2928), and dextran saccharase (Yamamoto K., Yoshikawa K., Okada S. (1994) Effective production of glucosyl-stevioside by .alpha.-1,6-transglucosylation of dextran dextranase. Biosci. Biotech. Biochem. 58: 1657-1661) have been used as transglycosylating enzymes, together with pullulan, maltose, lactose, and partially hydrolyzed starch, respectively, as donors of glycosidic residues.

The transglucosylation of steviol glycosides was also performed by action of cyclodextrin glucanotransferases (CGTase) produced by Bacillus stearothermophilus (U.S. Pat. Nos. 4,219,571, and 7,807,206) as a result .alpha.-1,4-glucosyl derivatives were formed with degree of polymerization up to 10.

It was shown that the taste profile and sweetness power of glucosyl derivatives are largely dependent on number of additional glucosyl derivatives, i.e. the degree of polymerization of the .alpha.-1,4-glucosyl chain. The increase in number of .alpha.-1,4-glucosyl residues improved the taste quality but at the same time reduced the sweetness level (Tanaka, 1987). The treatment of transglucosylated stevioside with .beta.-amylase resulted in a product consisting of mono- or di-.alpha.-1,4-glucosyl derivatives (Tanaka, 1987).

However in such processes, the resulting product contains a high level of initial unreacted (unmodified) glycosides (generally >20%) which makes it not compliant with regulatory requirements of less than 15% unreacted glycosides (.alpha.-Glucosyltransferase Treated Stevia, Japan's Specifications and Standards for Food Additives, VIII edition, 2009, p. 257). Therefore additional steps for chromatographic separation of unreacted steviol glycosides are used to reduce initial unreacted (unmodified) glycosides' content. However chromatographic separation techniques generally involve high cost and are not suitable for large scale production.

It is noted also that many glucosyl stevia products contain up to 20% residual dextrins which do not possess significant functional properties and reduce the content of steviol glycosides in the product.

Therefore it is necessary to develop high purity products with an optimal .alpha.-1,4-glucosyl chain length and low unreacted glycosides level which will deliver the best combination of sweetness potency and flavor profile.

SUMMARY OF THE INVENTION

The present invention is aimed to overcome the disadvantages of existing Stevia sweeteners. The invention describes a process for producing a high purity food ingredient from the extract of the Stevia rebaudiana Bertoni plant and use thereof in various food products and beverages as a sweetness and flavor modifier.

The invention, in part, pertains to an ingredient comprising glucosylated derivatives of steviol glycosides of Stevia rebaudiana Bertoni plant. The steviol glycosides are selected from the group consisting of stevioside, Rebaudioside A, Rebaudioside B, Rebaudioside C, Rebaudioside D, Rebaudioside E, Rebaudioside F, Rebaudioside X, dulcoside A, steviolbioside, rubusoside, as well as other steviol glycosides found in Stevia rebaudiana Bertoni plant and mixtures thereof.

The invention, in part, pertains to a process for producing an ingredient containing glucosylated forms of stevioside, Rebaudioside A, Rebaudioside B, Rebaudioside C, Rebaudioside D, Rebaudioside E, Rebaudioside F, Rebaudioside X, dulcoside A, steviolbioside, rubusoside, as well as other steviol glycosides found in Stevia rebaudiana Bertoni plant. The process can be an enzymatic transglucosylation process using CGTases produced by cultures of Bacillus stearothermophilus. The process may include the step of additional enzymatic treatment by .beta.-amylase or other enzymes. The process can also have the steps of decolorizing, desalting and removing maltooligosaccharides. The decolorizing can be performed using activated carbon. The desalting can be performed by passing through ion exchange resins and/or membrane filters. Removing the maltooligosaccharides can be performed by passing through macroporous polymeric resin.

In the invention, Stevia extract commercialized by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside (28-30%), Rebaudioside A (50-55%), Rebaudioside C (9-12%), Rebaudioside F (1-3%) and other glycosides amounting to total steviol glycosides' content of at least 95%, was used as a starting material. Alternatively stevia extracts with different ratio of steviol glycosides as well as highly purified steviol glycosides such as Rebaudioside A, stevioside, Rebaudioside D, Rebaudioside X, rubusoside etc, may be used as starting materials.

The starting material was subjected to the enzymatic transglucosylation by action of cyclodextrin glycosyltransferase (CGTase) in the presence of starch as a glucose donor. As a result .alpha.-1,4-glucosyl derivatives were formed, in some embodiments with degree of polymerization up to 20. The formed derivatives were optionally subjected to treatment with .beta.-amylase or other enzymes to produce .alpha.-1,4-glucosyl derivatives possessing a specific degree of polymerization.

The oligosaccharides from obtained reaction mixture were removed by Amberlite XAD7 HP resin, and then decolorized, deionized, concentrated and spray dried.

The obtained products were applied in various foods and beverages as sweeteners, sweetener enhancers, flavors and flavor modifiers, including soft drinks, ice cream, cookies, bread, fruit juices, milk products, baked goods and confectionary products.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

FIG. 1 shows a high-performance liquid chromatographic chromatogram of purified transglucosylated Stevia extract, without .beta.-amylase treatment containing long-chain .alpha.-1,4-glucosyl-derivatives with up to nine .alpha.-1,4-glucosyl residues;

FIG. 2 shows a high-performance liquid chromatographic chromatogram of purified transglucosylated Stevia extract after .beta.-amylase treatment with short-chain (containing four or less .alpha.-1,4-glucosyl residues) derivatives of stevioside and Rebaudioside A.

FIG. 3 shows a high-performance liquid chromatographic (HPLC) chromatogram of .beta.-amylase treated product containing mono- and di-.alpha.-1,4-glucosyl-derivatives of steviol glycosides, as well as high level of unreacted steviol glycoside;

FIG. 4 shows a high-performance liquid chromatographic (HPLC) chromatogram of .beta.-amylase treated product containing mono- and di-.alpha.-1,4-glucosyl-derivatives of steviol glycosides, as well as low level of unreacted steviol glycosides.

DETAILED DESCRIPTION OF THE INVENTION

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.

Stevia extract commercialized by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside (28-30%), Rebaudioside A (50-55%), Rebaudioside C (9-12%), Rebaudioside F (1-3%) and other glycosides (hereinafter collectively, "steviol glycosides") amounting to total steviol glycosides content of at least 95%, was used as a starting material. Alternatively stevia extracts with different ratio of steviol glycosides as well as highly purified steviol glycosides such as Rebaudioside A, stevioside, Rebaudioside D, Rebaudioside X, rubusoside etc, may be used as starting materials.

In certain embodiments, the steviol glycosides may be replaced, partially or completely, by compounds from the group consisting of Luo Han Guo extract, Siraitia grosvenorii extract, mogrosides, mogroside IIE, mogroside III, mogroside IV, mogroside V, mogroside VI, 11-oxo-mogroside V, siamenoside I, grosmomoside I, as well as other mogrol or oxo-mogrol glycosides found in Siraitia grosvenorii plant and mixtures thereof.

The HPLC analysis of the raw materials and products was performed on Agilent Technologies 1200 Series (USA) liquid chromatograph, equipped with Zorbax-NH.sub.2 (4.6.times.250 mm) column. The mobile phase was acetonitrile-water gradient from 80:20, v/v (0-2 min) to 50:50, v/v (2-70 min). A diode array detector set at 210 nm was used as the detector.

The transglucosylation was accomplished by cyclomaltodextrin glucanotransferases (CGTases; EC 2.4.1.19) produced by Bacillus stearothermophilus St-88 (PureCircle Sdn Bhd Collection of Industrial Microorganisms--Malaysia). However, any other CGTase or enzyme possessing intermolecular transglucosylation activity may be applied as well. The enzyme can be in a form of cell-free culture broth, concentrated liquid cell-free culture broth, spray dried or freeze dried cell-free culture broth, or high purity protein. Free and immobilized enzyme preparations can be used.

The activity of CGTase preparations was determined according to the procedure described in Hale W. S., Rawlins L. C. (1951) Amylase of Bacillus macerans. Cereal Chem. 28, 49-58.

Starches of different origin may be used as donors of glucosyl units such as, derived from wheat, corn, potato, tapioca, and sago.

Starch was subjected to partial hydrolysis (liquefaction) prior to the transglucosylation reaction. The dextrose equivalent of the partially hydrolyzed starch can be in the range of about 10-25, preferably about 12-16. Any enzyme capable of starch hydrolysis may be used for liquefaction, such as .alpha.-amylases, .beta.-amylases etc. In one embodiment, CGTase and .alpha.-amylase mixtures as liquefying enzymes are preferred.

.alpha.-Amylase activity is expressed in Kilo Novo .alpha.-amylase Units (KNU). One KNU is the amount of .alpha.-amylase which, under standard conditions (pH 7.1; 37.degree. C.), dextrinizes 5.26 g starch dry substance per hour.

The liquefaction mixture contains about 0.001-0.2 KNU, preferably about 0.05-0.1 KNU of .alpha.-amylase per one unit of CGTase.

The use of .alpha.-amylase in liquefaction allows achieving higher throughputs in further activated carbon filtration. When the CGTase is used as the only liquefying enzyme the filtration rate is approximately 10-15 L/hr per 1 m.sup.2 of filter surface. In case of liquefaction enzyme mixture (comprising .alpha.-amylase and CGTase) the filtration rate is twice as fast--approximately 20-30 L/hr per 1 m.sup.2 of filter surface.

The ratio of starch and CGTase in the liquefaction mixture is about 0.1-0.5 units per one gram of starch, preferably about 0.2-0.4 units per gram.

The concentration of starch in liquefaction mixture is about 15-40% (wt/wt), preferably about 20-30%.

The liquefaction is conducted at about 70-90.degree. C., or 75-80.degree. C., during about 0.5-5 hours, for example, about 0.5 to 2 hours, and preferably about 1-2 hours.

After liquefaction, the reaction mixture is subjected to thermal inactivation of .alpha.-amylase at low pH conditions. The preferred pH range for inactivation is about pH 2.5 to pH 3.0 and preferred temperature is about 95-105.degree. C. The duration of thermal inactivation is about 5-10 minutes.

After the inactivation, the pH of the reaction mixture is adjusted to about pH 5.5-6.5 and the steviol glycosides are added to the mixture and dissolved. The preferred ratio of steviol glycosides to starch (kg of steviol glycosides per 1 kg of starch) is about 0.5-1.5, preferably about 0.8-1.2.

A second portion of CGTase preparation is added and the transglucosylation reaction is conducted at temperature of between about 5-125.degree. C., such as 65.degree. C., for about to 168 hours, such as 24-48 hours. The amount of the second portion of CGTase is about 0.2-4 units of CGTase per gram of solids, preferably about 0.5-1.2 units per gram of solids.

After the addition of the second portion of the CGTase preparation, additional steps may include optionally inactivating the enzyme(s) in the reaction mixture; optionally decolorizing the reaction mixture; and optionally concentrating and drying the reaction mixture to obtain glucosyl stevia composition. In certain embodiments, the glucosyl stevia composition at this stage comprises steviol glycoside derivatives having twenty or less .alpha.-1,4-glucosyl residues.

Upon completion of transglucosylation reaction, further enzymatic treatment or treatments, and additional steps, can be used to arrive at the desired degree of polymerization and unreacted glycosides in the composition.

Further enzymatic treatment can include the addition of amylase, .beta.-amylase, maltase, glucoamylase, fructofuranosidase, glucosidase, glucanase, .beta.-glucanase, transglucosidase, glucosyltransferase, fructosyltransferase, galactosyltransferase, lactase, galactosidase, cellulase, pullulanase, xylanase, mannanase, Maltogenase.RTM., Fungamyl.RTM., Novamyl.RTM., Optimalt.RTM., or mixtures thereof, along with the substrate or substrates for the respective enzyme or enzymes utilized. The reaction mixture can be incubated for a period of time ranging from 0.0001 to 168 hours, at a temperature ranging from 5-125.degree. C.

Additional steps may include inactivating the enzymes in the reaction mixture by heat treatment; optionally decolorizing the reaction mixture; optionally removing non-diterpene compounds by contacting the decolorized reaction mixture with macroporous adsorbent resin and subsequently eluting adsorbed diterpene glycosides with alcohol or aqueous alcohol to result in a glycoside-containing eluate; optionally desalting the glycoside-containing eluate with ion-exchange resins; optionally removing alcohol from the eluate, resulting in an aqueous eluate; optionally concentrating and drying the aqueous eluate to obtain the dried glucosyl stevia composition, and optionally suspending the dried glucosyl stevia composition in aqueous alcohol, separating the crystals from suspension and drying them to obtain the desired glucosyl stevia composition.

The order of any of these steps may be changed depending on a variety of factors.

In certain embodiments, upon completion of transglucosylation reaction, about 30-50 units per gram of solids of .beta.-amylase was added and the reaction was continued for about 12-16 hours at about 35-55.degree. C., preferably about 45.degree. C. Soybean .beta.-amylase was used in this stage for Samples 1a and 2a, while the .beta.-amylase made in accordance with EXAMPLE 2 was used for Samples 1b and 2b. However .beta.-amylases derived from any other source including barley, bacterial, fungal .beta.-amylases and others may be used as well.

.beta.-Amylase activity unit (1 AUN) is defined as the activity which liberates 100 of reducing sugar (expressed by dextrose equivalent) per minute under the following conditions: 1 mL of enzyme solution is mixed with 5 mL of 1.2% starch solution (pH 5.5, M/20 Acetate Buffer) and kept for 20 min at 40.degree. C.

The reaction was stopped by heating at about 95.degree. C. for about 15 minutes to inactivate the enzymes, and the solution was treated with activated carbon, to obtain decolorized reaction mixture. The amount of activated carbon was about 0.02-0.4 grams per gram of solids, preferably about 0.05-0.2 grams per gram of solids. Other appropriate decolorizing methods, such as using ion exchange resins, membrane filtration using ultrafiltration, nanofiltration or reverse osmosis membranes, or other methods known in the art can be used.

Non-diterpene compounds may optionally be removed using, for example, a plurality of sequentially connected columns packed with a macroporous adsorbent resin, followed by washing the columns with water, then washing with about 10-50% (v/v) ethanol, disconnecting the columns, and then eluting each column individually with 30-100% ethanol.

The decolorized reaction mixture was desalted by passing through ion exchange resins, such as Amberlite FPC23 (H.sup.+ type) and Amberlite FPA51 (OH.sup.- type). Other appropriate decolorizing and desalting methods such as membrane filtration or other methods known in the art can be used.

The desalted reaction mixture was further concentrated by vacuum evaporator and dried by means of a spray dryer. Other appropriate concentrating and drying methods, such as membrane filtration, freeze drying, or other methods known to art can be used.

The dried powder was suspended in aqueous alcohol. The powder to aqueous alcohol ratio (wt/vol) was 1:1 to 1:20, preferably 1:3 to 1:10. The aqueous alcohol contained 0-50% (vol), preferably 1-10% water. The suspension is agitated at 30-100.degree. C., preferably 50-85.degree. C. during 1-24 hours, preferably 2-15 hours. Then the suspended solids are separated by means of filtration. Any other technique known in the art suitable for separating suspended solids from liquid such as centrifugation, decanting, etc. can be used. The obtained solids are dried in rotary drum vacuum drier. Any other dryer known in the art may be used as well. Alternatively the separated solids may be dissolved in water, evaporated from traces of alcohol and spray dried.

The alcohols employed in the invention may be selected from the group consisting of alkanols, and are preferably selected from the group including methanol, ethanol, n-propanol, 2-propanol, 1-butanol, and 2-butanol, or mixtures thereof.

In certain embodiments, the resulting product contains low level non-modified glycosides, short-chain (containing four or less, or two or less, .alpha.-1,4-glucosyl residues) derivatives and a mixture of maltooligosaccharides (Samples 1a and 1b). As used herein, the expressions "low level non-modified glycosides" or "low level unreacted glycosides" shall refer to glycoside levels of less than about 20%, and preferably less than about 15%, on an anhydrous basis. In some embodiments, an unreacted glycoside level of about 12%, about 10% or even lower can be attained using this method.

In order to prepare a product with higher content of total sweet glycosides (the sum of glucosylated and non-glucosylated glycosides), the maltooligosaccharides were removed using Amberlite XAD7 HP prior to the desalting treatment. The steviol glycosides and their glucosylated derivatives were adsorbed on the resin and subsequently eluted by aqueous ethanol. The resulted aqueous ethanol eluate, containing glucosyl steviol glycosides, was subsequently decolorized and desalted as described above and the glycosides solution, after the evaporation of eluting solvent, was powdered by spray drying. The dried powder was suspended in aqueous alcohol and processed as described above to remove unmodified (unreacted) steviol glycosides (Sample 2b). The resulting product contains low level non-modified glycosides, and short-chain (containing four or less, or two or less .alpha.-1,4-glucosyl residues) derivatives (Samples 2a and 2b).

The embodiments of the invention exemplified by Samples 1a, 1b, 2a and 2b are free or substantially free of higher glucosylated derivatives having more than 4 or more than 2 glucosyl residues. In accordance with this invention, the highly purified glucosyl stevia composition preferably comprises greater than about 25% by weight di-, tri- and tetraglucosyl Rebaudioside A, and greater than about 9% by weight tri- and tetraglucosyl steviosides. In another embodiment, the highly purified glucosyl stevia composition comprises greater than about 50% by weight mono-, and diglucosyl steviol glycosides.

Using a similar process as for Sample 2a, with exclusion of the .beta.-amylase treatment stage, a product containing non-modified glycosides and long chain .alpha.-1,4-glucosyl-derivatives (with up to nine .alpha.-1,4-glucosyl residues) was prepared (Sample 3).

As a control, a commercial .beta.-amylase treated product containing non-modified glycosides, and short-chain (containing two or less .alpha.-1,4-glucosyl residues) derivatives was used (Sample 4).

The composition of the samples is summarized in Tables 1a and 1b, in which Samples 1a and 2a made using the processes described above contain four or less .alpha.-1,4-glucosyl residues, and Samples 1b and 2b made using the processes described above contain two or less .alpha.-1,4-glucosyl residues.

TABLE-US-00001 TABLE 1a Composition of glucosyl steviol glycosides samples containing 4 or fewer .alpha.-1,4-glucosyl residues Content, % Sam- Sam- Sam- Sam- Compounds ple 1a ple 2a ple 3 ple 4 Stevioside 2.5 3.0 3.1 9.5 Rebaudioside C 0.9 1.0 1.0 0.4 Rebaudioside A 5.2 6.1 6.0 2.8 Monoglucosyl-stevioside (StevG1) 11.0 13.2 7.4 34.9 Monoglucosyl-Rebaudioside A 14.6 17.5 11.1 6.3 (RebAG1) Diglucosyl-stevioside (StevG2) 10.4 12.4 8.4 26.4 Diglucosyl-Rebaudioside A 15.6 18.6 9.6 -- (RebAG2) Triglucosyl-stevioside (StevG3) 5.8 7.0 6.3 -- Triglucosyl-Rebaudioside A 7.9 9.5 7.7 -- (RebAG3) Tetraglucosyl-stevioside (StevG4) 3.7 4.4 5.6 -- Tetraglucosyl-Rebaudioside A 2.9 3.4 6.1 -- (RebAG4) Higher glucosylated derivatives -- -- 22.7 -- Total content of glycosides 80.5 96.1 95.0 80.3

The sensory assessment of samples was carried using aqueous solutions, with 20 panelists. Based on overall acceptance the most desirable and most undesirable samples were chosen. The results are shown in Table 2a.

TABLE-US-00002 TABLE 2a Sensory assessment of samples in water system Sample Sample Sample Sample Judgment 1a 2a 3 4 Most desirable 5 11 1 2 Most 1 0 7 12 undesirable Sweetness 150 160 120 150 power Comments Sweet, light, Sweet, light, Sweet, Sweet, soft, round, soft, round, slightly slightly pleasant, pleasant, bitter, bitter, almost similar to astringent, astringent, similar to sucrose, no no lingering slight sucrose, no lingering aftertaste, lingering lingering aftertaste, sweetness aftertaste, aftertaste, sweetness onset is sweetness sweetness onset is moderate onset is slow onset is rapid rapid

As apparent from the results in Table 2a, the sweetness quality of the Samples 1a and 2a was rated as most superior. Overall the samples with short-chain (containing four or less .alpha.-1,4-glucosyl residues) derivatives (Sample 1a, and Samples 2a) possessed better taste profiles compared to samples with long-chain glucosyl derivatives (Sample 3) and two or less .alpha.-1,4-glucosyl residues short-chain derivatives (Sample 4).

Samples 1a and 2a show comparable sweetness power (150-160 times sweeter compared to a 5% sucrose solution) with control Sample 4 (150 times); however their flavor profile was clearly superior to the control sample.

A similar analysis was done for Samples 1b and 2b, which contain two or fewer .alpha.-1,4-glucosyl residues. Sample 5 was prepared in accordance with EXAMPLE 12.

TABLE-US-00003 TABLE 1b Composition of glucosyl steviol glycosides samples containing 2 or fewer .alpha.-1,4-glucosyl residues Content, % Sam- Sam- Sam- Sam- Compounds ple 1b ple 2b ple 3 ple 5 Stevioside 2.4 3.2 3.1 13.2 Rebaudioside C 0.7 1.0 1.0 3.0 Rebaudioside A 5.6 7.5 6.1 12.3 Monoglucosyl-stevioside (StevG1) 16.2 21.9 7.5 22.2 Monoglucosyl-Rebaudioside A 20.9 28.1 11.2 22.4 (RebAG1) Diglucosyl-stevioside (StevG2) 10.1 13.6 8.5 8.9 Diglucosyl-Rebaudioside A (RebAG2) 13.8 18.6 9.7 11.4 Higher glucosylated derivatives 1.3 1.7 48.8 1.8 Total content of unreacted glycosides 8.7 11.7 10.2 28.5 Total content of glycosides 71.0 95.5 95.8 95.3

The sensory assessment of samples was carried using aqueous solutions, with 20 panelists. Based on overall acceptance the most desirable and most undesirable samples were chosen. The results are shown in Table 2b.

TABLE-US-00004 TABLE 2b Sensory assessment of samples in water system Sample Sample Sample Sample Judgment 1b 2b 3 5 Most desirable 6 10 1 3 Most 1 0 12 7 undesirable Sweetness power 150 160 110 160 Comments Sweet, light, Sweet, light, Sweet, Sweet, soft, round, soft, round, slightly slightly pleasant, pleasant, bitter, bitter, almost similar to astringent, astringent, similar to sucrose, no slight slight sucrose, no lingering lingering lingering lingering aftertaste, aftertaste, aftertaste, aftertaste, sweetness sweetness sweetness sweetness onset is onset is onset is onset is rapid rapid moderate slow

As apparent from the results in Table 2b, the sweetness quality of the Samples 1b and 2b was rated as most superior. Overall the samples with short-chain (containing two or less .alpha.-1,4-glucosyl residues) derivatives and low level of unreacted glycosides (Samples 1b and 2b) possessed better taste profiles compared to samples with long-chain glucosyl derivatives (Sample 3) and short-chain (containing two or less .alpha.-1,4-glucosyl residues) derivatives and high level of unreacted glycosides (Sample 5).

Samples 1b and 2b show comparable sweetness power (150-160 times sweeter compared to a 5% sucrose solution) with control Sample 5 (160 times); however their flavor profile was clearly superior to the control Sample 5.

The compositions can be used as sweetness enhancers, flavors, flavor enhancers and sweeteners 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.

Additionally the 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.

The compositions can be used "as-is" or in combination with other sweeteners, flavors and food ingredients.

Non-limiting examples of sweeteners include steviol glycosides, stevioside, Rebaudioside A, Rebaudioside B, Rebaudioside C, Rebaudioside D, Rebaudioside E, Rebaudioside F, Rebaudioside X, 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, fructose, maltose, sucrose, lactose, aspartame, saccharin, sucralose, sugar alcohols, and combinations thereof.

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

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, and combinations thereof.

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 CGTase

A strain of Bacillus stearothermophilus St-88 was inoculated in 2,000 liters of sterilized culture medium containing 1.0% starch, 0.25% corn extract, 0.5% (NH.sub.4).sub.2SO.sub.4, and 0.2% CaCO.sub.3 (pH 7.0-7.5) at 56.degree. C. for 24 hrs with continuous aeration (2,000 L/min) and agitation (150 rpm). The obtained culture broth was filtered using Kerasep 0.1 .mu.m ceramic membrane (Novasep, France) to separate the cells. The cell-free permeate was further concentrated 2-fold on Persep 10 kDa ultrafilters (Orelis, France). The activity of the enzyme was determined according to Hale, Rawlins (1951). A crude enzyme preparation with activity of about 2 unit/mL was obtained.

EXAMPLE 2

Preparation of .beta.-Amylase

A strain of Bacillus polymyxa St-3504 was inoculated in 2,000 liters of sterilized culture medium containing 1.0% starch, 0.5% peptone, 0.5% corn extract, 0.5% NaCl, 0.02% MnSO.sub.4 and 0.1% CaCO.sub.3 (pH 7.0-7.5) at 32.degree. C. for 24 hrs with continuous aeration (2,000 L/min) and agitation (150 rpm). The obtained culture broth was filtered using Kerasep 0.1 .mu.m ceramic membrane (Novasep, France) to separate the cells. 10% of glucose was added to the cell-free permeate which was further concentrated on Persep 10 kDa ultrafilters (Orelis, France) and dried using Alpha 1-4 LSC freeze drier unit (Christ, Germany) to obtain a powder with 20,000 AUN/g activity. .beta.-Amylase activity unit (1 AUN) was defined as the activity which liberates 100 .mu.g of reducing sugar (expressed by dextrose equivalent) per minute under the following conditions: 1 mL of enzyme solution is mixed with 5 mL of 1.2% starch solution (pH 5.5, M/20 Acetate Buffer) and kept for 20 min at 40.degree. C.

EXAMPLE 3

Preparation of Short-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to EXAMPLE 1 were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15. The pH of reaction mixture was adjusted to pH 2.8 by hydrochloric acid and the mixture was boiled at 100.degree. C. during 5 minutes to inactivate the enzymes. After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation. Then the temperature was reduced to 45.degree. C., and 8,000 units soybean .beta.-amylase (#1500S, Nagase Chemtex Corp., Japan) was added to reaction mixture. The reaction was continued for another 12 hours. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzymes. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held for 30 minutes. The mixture was filtered and the filtrate was diluted with water to 5% solids content and passed through columns packed with Amberlite FPC23 (H.sup.+) and Amberlite FPA51 (OH.sup.-) ion exchange resins. The desalted solution was concentrated at 60.degree. C. under vacuum, and dried into a powder form using laboratory spray dryer. 196 grams of product was obtained (Sample 1a).

EXAMPLE 4

Preparation of Highly Purified Short-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to EXAMPLE 1 were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15. The pH of reaction mixture was adjusted to pH 2.8 by hydrochloric acid and the mixture was boiled at 100.degree. C. during 5 minutes to inactivate the enzymes. After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation. Then the temperature was reduced to 45.degree. C., and 8,000 units soybean .beta.-amylase (#1500S, Nagase Chemtex Corp., Japan) was added to reaction mixture. The reaction was continued for another 12 hours. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzymes. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held for 30 minutes. The mixture was filtered and the filtrate was diluted with water to 5% solids content and passed through columns each packed with 4000 mL Amberlite XAD 7HP macroporous adsorbent resin. The columns were washed with 5 volumes of water and 2 volumes of 20% (v/v) ethanol. The adsorbed glycosides were eluted with 50% ethanol. Obtained eluate was passed through columns packed with Amberlite FPC23 (H.sup.+) and Amberlite FPA51 (OH.sup.-) ion exchange resins. The ethanol was evaporated and the desalted and decolorized water solution was concentrated at 60.degree. C. under vacuum, then dried into a powder form using laboratory spray dryer. 151 grams of product was obtained (Sample 2a).

EXAMPLE 5

Preparation of Highly Purified Long-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to EXAMPLE 1 were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15. The pH of reaction mixture was adjusted to pH 2.8 by hydrochloric acid and the mixture was boiled at 100.degree. C. during 5 minutes to inactivate the enzymes. After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzyme. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held during 30 min. The mixture was filtered and the filtrate was diluted with water to 5% solids content and passed through columns each packed with 4000 mL Amberlite XAD 7HP macroporous adsorbent resin. The columns were washed with 5 volumes of water and 2 volumes of 20% (v/v) ethanol. The adsorbed glycosides were eluted with 50% ethanol. Obtained eluate was passed through columns packed with Amberlite FPC23 (H.sup.+) and Amberlite FPA51 (OH.sup.-) ion exchange resins. The ethanol was evaporated and the desalted and decolorized water solution was concentrated at 60.degree. C. under vacuum, then dried into a powder form using laboratory spray dryer. Approximately 165 grams of product was obtained (Sample 3).

EXAMPLE 6

Low-Calorie Orange Juice Drink

Orange concentrate (35%), citric acid (0.35%), ascorbic acid (0.05%), orange red color (0.01%), orange flavor (0.20%), Rebaudioside A (0.003%) and different glucosyl stevia compositions (0.03%) were blended and dissolved completely in water (up to 100%) and pasteurized. Glucosyl stevia compositions were represented by Samples 1a, 2a, and 3, obtained according to EXAMPLES 3, 4, and 5, respectively; and Sample 4 was a commercial .beta.-amylase treated product (containing only mono- and di-.alpha.-1,4-glucosyl-derivatives of steviol glycosides).

The sensory evaluations of the samples are summarized in Table 3. The data show that the best results can be obtained by using the high purity short-chain glucosyl stevia compositions (containing four or less .alpha.-1,4-glucosyl residues) derivatives (Samples 1a and 2a). Particularly the drinks prepared with Samples 1a and 2a exhibited a rounded and complete flavor profile and mouthfeel.

TABLE-US-00005 TABLE 3 Evaluation of orange juice drink samples Comments Mouth- Sample Flavor Aftertaste feel No. 1a High quality sweetness, Clean, almost no Full pleasant taste similar to bitterness, sucrose, rounded and no aftertaste balanced flavor No. 2a High quality sweetness, Clean, Full pleasant taste similar to no bitterness and sucrose, rounded and no aftertaste balanced flavor No. 3 High quality sweetness, Clean, almost no Almost pleasant taste almost bitterness, acceptable similar to no aftertaste sucrose, rounded and balanced flavor No. 4 Sweet, licorice notes Slight Not bitterness and acceptable aftertaste

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 7

Low-Calorie Carbonated Beverage

A carbonated beverage according to formula presented below was prepared.

TABLE-US-00006 Ingredients Quantity, % Sucrose 5.5 Cola flavor 0.340 ortho-Phosphoric acid 0.100 Sodium citrate 0.310 Sodium benzoate 0.018 Citric acid 0.018 Rebaudioside A 0.003 Glucosyl stevia composition 0.05 Carbonated water to 100

The sensory properties were evaluated by 20 panelists. The results are summarized in Table 4.

TABLE-US-00007 TABLE 4 Evaluation of low-calorie carbonated beverage samples Number of panelists detected the attribute Taste Sample Sample Sample Sample attribute No. 1a No. 2a No. 3 No. 4 Bitter taste 0 0 2 20 Astringent 1 0 3 20 taste Aftertaste 1 0 2 20 Comments Quality of Clean Clean Clean Bitter aftertaste sweet taste (19 of 20) (20 of 20) (17 of 20) (5 of 20) Overall Satisfactory Satisfactory Satisfactory Satisfactory evaluation (18 of 20) (20 of 20) (15 of 20) (3 of 20)

The above results show that the beverages prepared using Samples 1a and 2a possessed the best organoleptic characteristics.

EXAMPLE 8

Diet Cookies

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 glucosyl stevia compositions (0.03%) were kneaded well in dough-mixing machine. The obtained dough was molded and baked in oven at 200.degree. C. for 15 minutes. Glucosyl stevia compositions were by represented by Samples 1a, 2a, and 3, obtained according to EXAMPLES 3, 4, and 5, respectively; with Sample 4 being a commercial .beta.-amylase treated product (containing only mono- and di-.alpha.-1,4-glucosyl-derivatives of steviol glycosides).

The sensory properties were evaluated by 20 panelists. The best results were obtained in samples prepared by high purity short-chain glucosyl stevia compositions (containing four or less .alpha.-1,4-glucosyl residues) derivatives (Samples 1a and 2a). The panelists noted rounded and complete flavor profile and mouthfeel in cookies prepared with Samples 1a and 2a.

EXAMPLE 9

Yoghurt

Different glucosyl stevia compositions (0.03%) and sucrose (4%) were dissolved in low fat milk. Glucosyl stevia compositions were by represented by Samples 1a, 2a, and 3, obtained according to EXAMPLES 3, 4, and 5, respectively; with Sample 4 being a commercial .beta.-amylase treated product (containing only mono- and di-.alpha.-1,4-glucosyl-derivatives of steviol glycosides). After pasteurizing at 82.degree. C. for 20 minutes, the milk was cooled to 37.degree. C. A starter culture (3%) was added and the mixture was incubated at 37.degree. C. for 6 hours then at 5.degree. C. for 12 hours.

The sensory properties were evaluated by 20 panelists. The best results were obtained in samples prepared by high purity short-chain glucosyl stevia compositions (containing four or less .alpha.-1,4-glucosyl residues) derivatives (Samples 1a and 2a). The panelists noted rounded and complete flavor profile and mouthfeel in samples prepared with Samples 1a and 2a.

EXAMPLE 10

Preparation of Short-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to EXAMPLE 1 were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15. The pH of reaction mixture was adjusted to pH 2.8 by hydrochloric acid and the mixture was boiled at 100.degree. C. during 5 minutes to inactivate the enzymes. After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation. Then the temperature was reduced to 45.degree. C., and 8,000 units of .beta.-amylase obtained according to EXAMPLE 2 was added to reaction mixture. The reaction was continued for another 12 hours. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzymes. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held for 30 minutes. The mixture was filtered and the filtrate was diluted with water to 5% solids content and passed through columns packed with Amberlite FPC23 (H.sup.+) and Amberlite FPA51 (OH.sup.-) ion exchange resins. The desalted solution was concentrated at 60.degree. C. under vacuum, and dried into a powder form using laboratory spray dryer. The dried powder was suspended in 5 volumes of 95% aqueous ethanol. The suspension was agitated at 80.degree. C., during 12 hours. Then the suspended solids were separated by filtration. The obtained solids were dried in vacuum dryer at 90.degree. C. during 5 hours. 170 grams of product was obtained (Sample 1b).

EXAMPLE 11

Preparation of Highly Purified Short-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to EXAMPLE 1 were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15. The pH of reaction mixture was adjusted to pH 2.8 by hydrochloric acid and the mixture was boiled at 100.degree. C. during 5 minutes to inactivate the enzymes. After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation. Then the temperature was reduced to 45.degree. C., and 8,000 units of .beta.-amylase obtained according to EXAMPLE 2 was added to reaction mixture. The reaction was continued for another 12 hours. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzymes. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held for 30 minutes. The mixture was filtered and the filtrate was diluted with water to 5% solids content and passed through columns each packed with 4000 mL Amberlite XAD 7HP macroporous adsorbent resin. The columns were washed with 5 volumes of water and 2 volumes of 20% (v/v) ethanol. The adsorbed glycosides were eluted with 50% ethanol. Obtained eluate was passed through columns packed with Amberlite FPC23 (H.sup.+) and Amberlite FPA51 (OH.sup.-) ion exchange resins. The ethanol was evaporated and the desalted and decolorized water solution was concentrated at 60.degree. C. under vacuum, then dried into a powder form using laboratory spray dryer. The dried powder was suspended in 5 volumes of 95% aqueous ethanol. The suspension was agitated at 80.degree. C., during 12 hours. Then the suspended solids were separated by filtration. The obtained solids were dried in vacuum dryer at 90.degree. C. during 5 hours. 121 grams of product was obtained (Sample 2b).

EXAMPLE 12

Preparation of Highly Purified Short-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to EXAMPLE 1 were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15. The pH of reaction mixture was adjusted to pH 2.8 by hydrochloric acid and the mixture was boiled at 100.degree. C. during 5 minutes to inactivate the enzymes. After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation. Then the temperature was reduced to 45.degree. C., and 8,000 units of .beta.-amylase obtained according to EXAMPLE 2 was added to reaction mixture. The reaction was continued for another 12 hours. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzymes. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held for 30 minutes. The mixture was filtered and the filtrate was diluted with water to 5% solids content and passed through columns each packed with 4000 mL Amberlite XAD 7HP macroporous adsorbent resin. The columns were washed with 5 volumes of water and 2 volumes of 20% (v/v) ethanol. The adsorbed glycosides were eluted with 50% ethanol. Obtained eluate was passed through columns packed with Amberlite FPC23 (H.sup.+) and Amberlite FPA51 (OH.sup.-) ion exchange resins. The ethanol was evaporated and the desalted and decolorized water solution was concentrated at 60.degree. C. under vacuum, then dried into a powder form using laboratory spray dryer. 154 grams of product was obtained (Sample 5).

EXAMPLE 13

Preparation of Long-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to EXAMPLE 1 were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15. The pH of reaction mixture was adjusted to pH 2.8 by hydrochloric acid and the mixture was boiled at 100.degree. C. during 5 minutes to inactivate the enzymes. After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzyme. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held during 30 min. The mixture was filtered and the filtrate was concentrated at 60.degree. C. under vacuum, then dried into a powder form using laboratory spray dryer. 197 grams of product was obtained (Sample 6).

EXAMPLE 14

Low-Calorie Orange Juice Drink

Orange concentrate (35%), citric acid (0.35%), ascorbic acid (0.05%), orange red color (0.01%), orange flavor (0.20%), Rebaudioside A (0.003%) and different glucosyl stevia compositions (0.03%) were blended and dissolved completely in water (up to 100%) and pasteurized. Glucosyl stevia compositions were represented by Samples 1b, 2b, 3, 5 and 6, obtained according to EXAMPLES 10, 11, 5, 12, and 13 respectively.

The sensory evaluations of the samples are summarized in Table 5. The data show that the best results can be obtained by using the high purity short-chain glucosyl stevia compositions (containing two or less .alpha.-1,4-glucosyl residues and low unreacted steviol glycosides) (Samples 1b and 2b). Particularly the drinks prepared with Samples 1b and 2b exhibited a rounded and complete flavor profile and mouthfeel.

TABLE-US-00008 TABLE 5 Evaluation of orange juice drink samples Comments Mouth- Sample Flavor Aftertaste feel No. 1b High quality sweetness, Clean, almost no Full pleasant taste similar to bitterness, sucrose, rounded and no aftertaste balanced flavor No. 2b High quality sweetness, Clean, no Full pleasant taste similar to bitterness and sucrose, rounded and no aftertaste balanced flavor No. 3 High quality sweetness, Clean, almost no Almost pleasant taste almost bitterness, no aftertaste acceptable similar to sucrose, rounded and balanced flavor No. 5 Sweet, licorice notes Slight bitterness and Not aftertaste acceptable

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 15

Low-Calorie Carbonated Beverage

A carbonated beverage according to formula presented below was prepared.

TABLE-US-00009 Ingredients Quantity, % Sucrose 5.5 Cola flavor 0.340 ortho-Phosphoric acid 0.100 Sodium citrate 0.310 Sodium benzoate 0.018 Citric acid 0.018 Rebaudioside A 0.003 Glucosyl stevia composition 0.05 Carbonated water to 100

The sensory properties were evaluated by 20 panelists. The results are summarized in Table 6.

TABLE-US-00010 TABLE 6 Evaluation of low-calorie carbonated beverage samples Number of panelists detected the attribute Taste Sample Sample Sample Sample attribute No. 1b No. 2b No. 3 No. 5 Bitter taste 0 0 10 12 Astringent 1 0 15 15 taste Aftertaste 1 0 13 18 Comments Quality of Clean Clean Clean Bitter aftertaste sweet taste (18 of 20) (20 of 20) (14 of 20) (10 of 20) Overall Satisfactory Satisfactory Satisfactory Satisfactory evaluation (19 of 20) (20 of 20) (11 of 20) (9 of 20)

The above results show that the beverages prepared using Samples 1b and 2b possessed the best organoleptic characteristics.

EXAMPLE 16

Diet Cookies

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 glucosyl stevia compositions (0.03%) were kneaded well in dough-mixing machine. The obtained dough was molded and baked in oven at 200.degree. C. for 15 minutes. Glucosyl stevia compositions were represented by Samples 1b, 2b, 3, and 5, obtained according to EXAMPLES 10, 11, 5, and 12, respectively.

The sensory properties were evaluated by 20 panelists. The best results were obtained in samples prepared by high purity short-chain glucosyl stevia compositions (containing two or less .alpha.-1,4-glucosyl residues) derivatives (Samples 1b and 2b). The panelists noted rounded and complete flavor profile and mouthfeel in cookies prepared with Samples 1b and 2b.

EXAMPLE 17

Yoghurt

Different glucosyl stevia compositions (0.03%) and sucrose (4%) were dissolved in low fat milk. Glucosyl stevia compositions were represented by Samples 1b, 2b, 3, and 5, obtained according to EXAMPLES 10, 11, 5, and 12, respectively. After pasteurizing at 82.degree. C. for 20 minutes, the milk was cooled to 37.degree. C. A starter culture (3%) was added and the mixture was incubated at 37.degree. C. for 6 hours then at 5.degree. C. for 12 hours.

The sensory properties were evaluated by 20 panelists. The best results were obtained in samples prepared by high purity short-chain glucosyl stevia compositions (containing two or less .alpha.-1,4-glucosyl residues) derivatives (Samples 1b and 2b). The panelists noted rounded and complete flavor profile and mouthfeel in samples prepared with Samples 1b and 2b.

COMPARATIVE EXAMPLE 1

Preparation of Highly Purified Short-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to the procedure described above were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15.

After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation.

Then the temperature was reduced to 45.degree. C., and 8,000 units soybean .beta.-amylase (#1500S, Nagase Chemtex Corp., Japan) was added to reaction mixture. The reaction was continued for another 12 hours. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzymes. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held for 30 minutes. The mixture was filtered and the filtrate was diluted with water to 5% solids and was passed through columns packed with Amberlite FPC23 (H.sup.+) and Amberlite FPA51 (OH.sup.-) ion exchange resins and then through columns each packed with 4000 mL Amberlite XAD 7HP macroporous adsorbent resin. The macroporous resin columns were washed with 5 volumes of water and 2 volumes of 20% (v/v) ethanol. The adsorbed glycosides were eluted with 50% ethanol. The ethanol of obtained eluate was evaporated and concentrated at 60.degree. C. under vacuum, then dried into a powder form using laboratory spray dryer. 114 grams of product was obtained (Sample 7).

The Sample 7 composition was analyzed using HPLC, and its sensory assessment along with other samples (Samples 1a, 2a, 3 and 4) was carried out using aqueous solutions, with 20 trained panelists.

Composition of Glucosyl Steviol Glycoside Samples

TABLE-US-00011 Content, % Sam- Sam- Sam- Sam- Sam- Compounds ple 1a ple 2a ple 3 ple 4 ple 7 Stevioside 2.5 3.0 3.1 9.5 17.1 Rebaudioside C 0.9 1.0 1.0 0.4 4.2 Rebaudioside A 5.2 6.1 6.0 2.8 27.7 Monoglucosyl-stevioside 11.0 13.2 7.4 34.9 13.9 (StevG1) Monoglucosyl-Rebaudioside A 14.6 17.5 11.1 6.3 17.1 (RebAG1) Diglucosyl-stevioside 10.4 12.4 8.4 26.4 5.9 (StevG2) Diglucosyl-Rebaudioside A 15.6 18.6 9.6 -- 7.2 (RebAG2) Triglucosyl-stevioside 5.8 7.0 6.3 -- 1.1 (StevG3) Triglucosyl-Rebaudioside A 7.9 9.5 7.7 -- 1.4 (RebAG3) Tetraglucosyl-stevioside 3.7 4.4 5.6 -- -- (StevG4) Tetraglucosyl-Rebaudioside A 2.9 3.4 6.1 -- -- (RebAG4) Higher glucosylated derivatives -- -- 22.7 -- -- Unreacted glycosides 8.6 10.1 10.1 12.7 49.0 (Stev + RebC + RebA) Total content of glycosides 80.5 96.1 95.0 80.3 95.6

Sensory Assessment of Samples in Water System

TABLE-US-00012 Sam- Sam- Sam- Sam- Sam- Judgment ple 1a ple 2a ple 3 ple 4 ple 7 Most desirable 6 11 1 2 0 Most 0 0 4 6 10 undesirable Comments Sweet, light, Sweet, light, Sweet, Sweet, Sweet, soft, round, soft, round, slightly slightly bitter, pleasant, pleasant, bitter, bitter, astringent, almost similar to astringent, astringent, lingering similar to sucrose, no no lingering slight aftertaste, sucrose, no lingering aftertaste, lingering sweetness lingering aftertaste, sweetness aftertaste, onset is aftertaste, sweetness onset is sweetness slow sweetness onset is moderate onset is onset is rapid rapid slow

COMPARATIVE EXAMPLE 2

Preparation of Highly Purified Short-Chain Glucosyl Stevia Composition

100 g of tapioca starch was suspended in 300 mL of water (pH 6.5). 2 KNU of .alpha.-amylase (Termamyl Classic, Novozymes, Denmark) and 30 units of CGTase obtained according to the procedure described above were added, and the liquefaction of starch was carried out at 80.degree. C. for about one hour to dextrose equivalent about 15. After cooling to 65.degree. C., the pH was adjusted to pH 6.0 with sodium hydroxide solution. 100 g stevia extract produced by PureCircle (JiangXi) Co., Ltd. (China), containing stevioside 29.2%, Rebaudioside A 54.3%, Rebaudioside C 9.0%, Rebaudioside F (1.7%) and other glycosides amounting to total steviol glycosides content of about 96.4% was added to liquefied starch and stirred until a homogeneous solution was obtained. 200 units of CGTase was added to the solution and the mixture was held at a temperature of 65.degree. C. for 24 hours under continuous agitation. Then the temperature was reduced to 45.degree. C., and 8,000 units of .beta.-amylase obtained according to the procedure described above was added to reaction mixture. The reaction was continued for another 12 hours. The obtained reaction mixture was heated at 95.degree. C. for 15 minutes to inactivate the enzymes. 20 grams of activated carbon was added and the mixture was heated to 75.degree. C. and held for 30 minutes. The mixture was filtered and the filtrate was diluted with water to 5% solids and was passed through columns packed with Amberlite FPC23 (H.sup.+) and Amberlite FPA51 (OH.sup.-) ion exchange resins and then through columns each packed with 4000 mL Amberlite XAD 7HP macroporous adsorbent resin. The macroporous resin columns were washed with 5 volumes of water and 2 volumes of 20% (v/v) ethanol. The adsorbed glycosides were eluted with 50% ethanol. The ethanol of obtained eluate was evaporated and concentrated at 60.degree. C. under vacuum, then dried into a powder form using laboratory spray dryer. The dried powder was suspended in 5 volumes of 95% aqueous ethanol. The suspension was agitated at 80.degree. C., during 12 hours. Then the suspended solids were separated by filtration. The obtained solids were dried in vacuum dryer at 90.degree. C. during 5 hours. 67 grams of product was obtained (Sample 8).

The Sample 8 composition was analyzed using HPLC, and its sensory assessment along with other samples (Samples 1b, 2b, 3, and 5 as described above) was carried out using aqueous solutions, with 20 trained panelists.

Composition of Glucosyl Steviol Glycoside Samples

TABLE-US-00013 Content, % Sam- Sam- Sam- Sam- Sam- Compounds ple 1b ple 2b ple 3 ple 5 ple 8 Stevioside 2.4 3.2 3.1 13.2 20.79 Rebaudioside C 0.7 1.0 1.0 3.0 6.15 Rebaudioside A 5.6 7.5 6.1 12.3 32.46 Monoglucosyl-stevioside 16.2 21.9 7.5 22.2 12.95 (StevG1) Monoglucosyl-Rebaudioside A 20.9 28.1 11.2 22.4 18.57 (RebAG1) Diglucosyl-stevioside 10.1 13.6 8.5 8.9 1.69 (StevG2) Diglucosyl-Rebaudioside A 13.8 18.6 9.7 11.4 2.40 (RebAG2) Higher glucosylated derivatives 1.3 1.7 48.8 1.8 -- Total content of unreacted 8.7 11.7 10.2 28.5 59.4 glycosides Total content of glycosides 71.0 95.5 95.8 95.3 95.0

Sensory Assessment of Samples in Water System

TABLE-US-00014 Sample Sample Sample Sample Sample Judgment 1b 2b 3 5 8 Most desirable 7 10 1 2 0 Most 0 0 5 4 11 undesirable Comments Sweet, light, Sweet, light, Sweet, Sweet, Sweet, soft, round, soft, round, slightly slightly bitter, pleasant, pleasant, bitter, bitter, astrin- almost similar to astrin- astrin- gent, lingering similar to sucrose, no gent, slight gent, slight aftertaste, sucrose, no lingering lingering lingering sweetness lingering aftertaste, aftertaste, aftertaste, onset is aftertaste, sweetness sweetness sweetness slow sweetness onset is onset is onset is onset is rapid rapid moderate slow

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.