Process for manufacturing a sweetener and use thereof
Highly purified Stevioside and Rebaudioside A were prepared from sweet glycoside extracts obtained from Stevia rebaudiana Bertoni leaves. The resulting sweeteners are suitable as non-calorie, non-cariogenic, non-bitter, non-lingering sweeteners, which may be advantageously applied in foods, beverages, and milk products.
1. A process for producing a sweetener, comprising of the following steps:
a) drying Stevia rebaudiana leaves;
b) treating the dried Stevia rebaudiana leaves with water to extract sweet glycosides, wherein a leaves-water mixture is formed;
c) filtering the leaves-water mixture to obtain an aqueous filtrate;
d) directly treating the aqueous filtrate with calcium hydroxide or calcium oxide to raise the pH of the aqueous filtrate to about 10;
e) directly neutralizing the treated aqueous filtrate with trivalent iron chloride; and
f) filtrating the neutralized aqueous filtrate to obtain a filtrated aqueous filtrate, and evaporating the filtrated aqueous filtrate to dryness to obtain purified sweet glycosides.
2. The process of claim 1 , wherein the treating step (b) is performed with a water content of at least 5 to 15 liters per 1 kg of dry leaves, a treating time is 0.5-24 hours and a temperature range is between 25-90° C.
3. The process of claim 2 , wherein the treating time is 1-6 hours.
4. The process of claim 2 , wherein the treating temperature range is 45-75° C.
5. The process of claim 1 , wherein the treating the extract with base step (d) is performed at a temperature range from 40° C. to 60° C. for 0.5-1 hours.
6. The process of claim 5 , wherein the step (d) temperature range is 50-55° C.
7. A purification process for Rebaudioside A and Stevioside, which comprises the following steps:
a) dissolving the purified sweet glycosides of claim 1 in methanol at temperatures 20-50° C. in an amount of 1:2-1:7 (w/v) to precipitate Stevioside from solution;
b) filtering the solution from step (a) to recover the precipitate of Stevioside;
c) suspending the precipitate of Stevioside obtained in step (b) in an alcohol-water solution to further purify the Stevioside; and
e) recovering the higher purity of Stevioside with a purity of at least 98%.
8. The process of claim 7 , wherein the step (c) was performed at 10-12° C.
9. The process of claim 7 , which further comprises:
combining remaining alcohol solutions;
removing the alcohol;
ultrafiltering to obtain a filtrate; and
recovering the Rebaudioside A.
10. The process of claim 9 , wherein the step of removing the alcohol is performed by evaporation.
11. The process of claim 9 , wherein the recovering the Rebaudioside A step comprises:
drying the ultrafiltration filtrate;
mixing with an alcohol solution;
filtering and drying.
12. The process of claim 11 , wherein the mixing with an alcohol solution step uses 96.2% ethanol at 50° C. for 30 minutes.
13. The process of claim 11 , which further comprises:
mixing with dilute alcohol; and
filtering and drying;
wherein the Rebaudioside A has a purity of at least 98%.
14. The process of claim 13 , wherein the mixing with dilute alcohol step is performed with 92% ethanol at 12° C. for 60 minutes.