Description:METHOD FOR EXTRACTING SWEETENING COMPONENTS FROM STEVIA REBAUDIANA

TECHNICAL FIELD
[001] The subject described herein, in general, relates to extraction of sweetening components from stevia rebaudiana, more particularly but not exclusively the subject matter relates to a simple process for extraction of the sweetening components by aqueous treatment.

BACKGROUND OF THE INVENTION
[002] Steviosides are natural sweeteners, which are added to low-calorie foods or as replacement for cane sugar. Due to their sweetening property and anti-diabetic effect, isolation and purification of the steviosides from dried stevia leaves have been a major concern world-wide especially, in the field of natural product chemistry.

[003] Conventionally, the steviosides are extracted and purified by using organic solvents, such as methanol or ethanol, among others. Such conventional methodologies are time-consuming and expensive. Further, the final product obtained from said process is not cost-effective, making it unaffordable for consumers.

[004] In view of the foregoing, there is a need for an improved process that is simple and inexpensive and involves minimal or no usage of the organic solvents in extracting the steviosides.

SUMMARY
[005] According to the present disclosure, a method for extracting all sweetening components from dried stevia leaves is provided. The method comprises drying leaves of Stevia rebaudiana, and boiling the dried leaves of Stevia rebaudiana in water to obtain an aqueous extract, wherein a ratio of the Stevia rebaudiana to the water is 25 gram: 1 litre. Further, during the boiling of the stevia leaves, evaporated water gets condensed and condensed water is reused. The aqueous extract so obtained is further subjected to drying at a temperature of 1050C and 1090C to obtain stevioside powder using a micro spray drier.

[006] In an embodiment, the leaves of Stevia rebaudiana are dried in a dehydrate dryer.

[007] In another embodiment, the leaves of Stevia rebaudiana are boiled for a time period ranging between three hours and five hours.

[008] In yet another embodiment, the drying of the aqueous extract is carried by a process selected from the group consisting of decantation, centrifugation, filtration, evaporation, vacuum, spray-drying and a combination thereof.

[009] In yet another embodiment, the aqueous extract is subjected to a spray dryer for spray drying.

[0010] In yet another embodiment, the spray dryer is the micro spray dryer/drier.

[0011] In yet another embodiment, the boiling is carried out in an evaporation tank.

[0012] In yet another embodiment, the evaporation tank is a vacuum evaporator comprising a condenser.

[0013] In yet another embodiment, the sweeting components comprise stevioside (6-8%), rebaudioside (2-4%) and minor diterpene glycosides.

[0014] In yet another embodiment, the stevioside powder obtained can withstand a temperature above 2000C without affecting texture and quality.

BRIEF DESCRIPTION OF DRAWINGS
[0015] Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:

[0016] FIG. 1 is a flowchart illustrating a method for extracting all sweetening components (steviosides) stevia leaves, in accordance with an embodiment;

[0017] FIG. 2 is a graph illustrating an increase in concentration of the steviosides with increase in extraction time, in accordance with an embodiment; and

[0018] FIG. 3 illustrates stevioside/stevia powder obtained by the method of FIG.1, in accordance with an embodiment.

DETAILED DESCRIPTION
[0019] The following detailed description includes references to the accompanying drawings, which form part of the detailed description. The drawings show illustrations in accordance with example embodiments. These example embodiments are described in enough details to enable those skilled in the art to practice the present subject matter. However, it may be apparent to one with ordinary skill in the art that the present invention may be practised without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to unnecessarily obscure aspects of the embodiments. The embodiments can be combined, other embodiments can be utilized or structural and logical changes can be made without departing from the scope of the invention. The following detailed description is, therefore, not to be taken as a limiting sense.

[0020] In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one. In this document, the term “or” is used to refer to a non-exclusive “or”, such that “A or B” includes “A but not B”, “B but not A”, and “A and B”, unless otherwise indicated.

[0021] FIG.1 illustrates a method 100 for extracting all sweetening components from stevia leaves, in accordance with an embodiment. The process or method of the present invention is simple and involves rapid processing technology for the extraction of all the sweetening components totally called as stevioside from the stevia leaves without affecting the quantity and the quality of stevioside, using water as a solvent.

[0022] At step 102, the stevia leaves obtained from stevia rebaudiana are dried. The drying of the leaves is carried out to remove moisture or reduce the moisture content. The stevia leaves collected from good variety of stevia may be used, as the stevia leaves increase the yield. For example, the stevia leaves from plants grown at higher altitude regions may be collected, which increases the yield.

[0023] In an embodiment, the leaves are dried in a dryer configured to remove moisture from the leaves. The dryer is for example, but is not limited to, a dehydrate dryer. The dryer used can be any dryer that serves the purpose of the present invention.

[0024] At step 104, the dried leaves are subjected to boiling in an evaporation tank. The leaves are boiled in water (aqueous phase) to obtain an aqueous extract or concentrate. In other words, the leaves are subjected to aqueous treatment.

[0025] In an embodiment, the evaporation tank is a vacuum evaporator comprising a condenser. Further, the boiling can be carried out in any apparatus that serves the purpose of the present invention.

[0026] In an embodiment, the boiling is carried out for a time period ranging between 3 hours and 5 hours. The water evaporating during the boiling of the leaves gets condensed such that the condensed water is reused.

[0027] In an embodiment, the ratio of the Stevia rebaudiana leaves to the water is 25 gram: 1 litre. Moreover, the ratio of the Stevia rebaudiana leaves to the water may be varied based on the requirement such that boiling is carried out efficiently. The boiling is carried out in sufficient amount of water.

[0028] At step 106, the aqueous extract obtained at step 104 is subjected to drying to obtain stevioside powder shown in FIG.3. The stevioside/ stevia powder obtained by the present invention contains all the sweetening components such as, stevioside (6-8%), rebaudioside (2-4%) and other minor diterpene glycosides.

[0029] In an embodiment, the drying of the aqueous extract is carried out by a process selected from the group consisting of decantation, centrifugation, filtration, evaporation, vacuum, spray-drying and a combination thereof.

[0030] In an embodiment, the aqueous extract is subjected to a spray dryer for spray drying, so that water is removed. For example, the spray dryer may be a micro spray dryer. For an example, the micro spray drying is performed at a temperature of 105/195 ºC inlet and 109ºC out let temperature.

[0031] Table.1 provided below shows the concentration of the stevioside during extraction.

Trials Time Interval Concentration of stevioside Percentage
1 45 minutes 2.53 g 2%
2 90 minutes 5.71 g 5%
3 135 minutes 8.87 g 8%
4 180 minutes 12.11 g 12%

[0032] From the table, it is evident that if the time interval of extraction is increased the concentration of the stevioside also increases. The concentration of the stevioside is determined spectrophotometrically at 200 nm. FIG.2 illustrates a graph depicting the increase in concentration of the stevioside with the increase in the time for extraction.

[0033] In an embodiment, cytotoxicity of the stevioside is checked by MTT (3-(4,5-dimethyl'thiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay in human cell lines. The stevioside powder obtained showed anti-hyperglycemic effect and can withstand the temperature above 200ºC without affecting the texture and quality.

[0034] The process of the present invention is cost effective compared to isolation procedure standardized by modern tools and techniques. Moreover, the steviosides extracted by aqueous treatment showed all the properties as a natural sweetener. The residue stevia leaves after said extraction process, have no sweetness indicating the efficacy of complete extraction of stevioside from the leaves.

[0035] Although embodiments have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the system and method described herein. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

[0036] Many alterations and modifications of the present invention will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. It is to be understood that the description above contains many specifications; these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the personally preferred embodiments of this invention. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents rather than by the examples given.
, Claims:We Claim:
1. A method (100) for extracting sweetening components from stevia leaves, the method comprising:
a) drying (102) leaves of Stevia rebaudiana;
b) boiling (104) the dried leaves of Stevia rebaudiana in water to obtain an aqueous extract, wherein a ratio of the Stevia rebaudiana leaves to the water is 25 gram:1 litre, wherein during the boiling of the stevia leaves, evaporated water gets condensed and condensed water is reused; and
c) drying (106) the aqueous extract to remove water at a temperature of 105/195 ºC inlet and 109ºC out let to obtain stevioside powder comprising the sweeting components.

2. The method (100) as claimed in claim 1, wherein the leaves of Stevia rebaudiana are dried in a dehydrate dryer.

3. The method (100) as claimed in claim 1, wherein the leaves of Stevia rebaudiana are boiled for a time period ranging between three hours and five hours.

4. The method (100) as claimed in claim 1, wherein the drying of the aqueous extract is carried by a process selected from the group consisting of decantation, centrifugation, filtration, evaporation, vacuum, spray-drying and a combination thereof.

5. The method (100) as claimed in claim 4, wherein the aqueous extract is subjected to a spray dryer for spray drying.

6. The method (100) as claimed in claim 5, wherein the spray dryer is a micro spray dryer.

7. The method (100) as claimed in claim 1, wherein the boiling is carried out in an evaporation tank.

8. The method (100) as claimed in claim 7, wherein the evaporation tank is a vacuum evaporator comprising a condenser.

9. The method (100) as claimed in claim 1, wherein the sweeting components comprise stevioside (6-8%), rebaudioside (2-4%) and minor diterpene glycosides.

10. The method (100) as claimed in claim 1, wherein the stevioside powder obtained can withstand a temperature above 2000C without affecting texture and quality.