Sweetening compositions and processes for preparing them
The invention relates to sweetening compositions obtained from the Luo Han Guo fruit, a member of the Cucurbiticeae family. The compositions are free of bitter-tasting impurities, have a light colour and contain about 16-75% mogroside V and about 30-95% total terpene glycosides on a dry weight basis. A filtered (0.2 μm) solution of the composition in water with a solids content of 1% w/v has an absorbance at 420 nm of about 0.55 or below. Also disclosed is a method of preparing such compositions which includes a heating step to encourage the formation of melanoidins, highly coloured impurities, thereby permitting their removal by filtration providing a lighter coloured product.
1. A process of preparing a sweetening composition containing terpene glycosides, the process comprising:
(a) obtaining a terpene glycoside-containing liquid extract from a fresh plant source material containing terpene glycosides;
(b) clarifying the extract;
(c) concentrating terpene glycosides in the clarified extract to obtain a purified terpene glycoside-containing solution;
(d) heating the purified terpene glycoside-containing solution to a sufficient temperature and for a sufficient time to form melanoidins; and
(e) contacting the heated purified terpene glycoside-containing solution with a decolourising resin which binds melanoidins formed, thereby separating melanoidins from terpene glycosides in the solution to obtain a decolourised terpene glycoside-containing solution,
wherein the decolourising resin comprises an anion resin regenerated in a chloride form, and
wherein a filtered (0.2 μm) decolourised terpene glycoside-containing solution in water having a solids content of 1% w/v has an absorbance at 420 nm about 0.55 or below.
2. The process according to claim 1 , wherein the fresh plant source material is Luo Han Guo fruit.
3. The process according to claim 1 , wherein step (a) comprises contacting macerated Luo Han Guo fruit with hot water, at a sufficient time and for a sufficient temperature to extract triterpene glycosides from the fruit.
4. The process according to claim 3 , wherein the extraction is carried out using counter current extraction.
5. The process according to claim 1 , wherein the clarification step (b) comprises ultrafiltration of the extract.
6. The process according to claim 1 , wherein the decolourising resin used in step (e) comprises a highly porous, macroporous, type I, strongly basic anion resin.
7. A process of preparing a sweetening composition from a fresh plant source material containing terpene glycosides, wherein the process comprises:
(a) heating a terpene glycoside-containing solution obtained by extracting terpene glycosides from the plant source material to a sufficient temperature and for a sufficient time to form melanoidins; and
(b) contacting the heated terpene glycoside-containing solution with a decolourising resin which binds melanoidins formed, thereby separating melanoidins from the terpene glycosides in the solution to obtain a decolourised terpene glycoside-containing solution,
wherein the decolourising resin comprises an anion resin regenerated in a chloride form, and wherein a filtered (0.2 μm) decolourised terpene glycoside-containing solution in water having a solids content of 1% w/v has an absorbance at 420 nm about 0.55 or below.
8. The process of claim 1 , wherein the decolourised terpene glycoside-containing solution comprises about 16% to about 75% mogroside V, on a dry weight basis.
9. The process of claim 7 , wherein the decolourised terpene glycoside-containing solution comprises about 16% to about 75% mogroside V, on a dry weight basis.
10. The process of claim 1 , wherein the decolourised terpene glycoside-containing solution comprises about 30% to about 95% terpene glycosides, on a dry weight basis.
11. The process of claim 7 , wherein the decolourised terpene glycoside-containing solution comprises about 30% to about 95% terpene glycosides, on a dry weight basis.
12. The process of claim 1 , wherein a filtered (0.2 μm) decolourised terpene glycoside-containing solution in water having a solids content of 1% w/v has an absorbance at 420 nm less than about 0.5.
13. The process of claim 7 , wherein a filtered (0.2 μm) decolourised terpene glycoside-containing solution in water having a solids content of 1% w/v has an absorbance at 420 nm less than about 0.5.
14. A process of preparing a sweetening composition from a fresh plant source material containing terpene glycosides, wherein the process comprises:
(a) extracting terpene glycosides from the fresh plant source material to produce a terpene glycoside-containing liquid extract;
(b) heating the extract to a sufficient temperature and for a sufficient time to form melanoidins;
(c) providing a decolourising resin;
(d) regenerating the decolourising resin in a chloride form; and
(e) contacting the heated extract from step (b) with the decolourising resin from step (d) which binds melanoidins formed, thereby separating melanoidins from the terpene glycosides in the extract to obtain a decolourised terpene glycoside-containing solution,
wherein the decolourising resin comprises an anion resin regenerated in a chloride form, and wherein a filtered (0.2 μm) decolourised terpene glycoside-containing solution in water having a solids content of 1% w/v has an absorbance at 420 nm about 0.55 or below.
15. The process of claim 14 , wherein a filtered (0.2 μm) decolourised terpene glycoside-containing solution in water having a solids content of 1% w/v has an absorbance at 420 nm less than about 0.5.
16. The process of claim 14 , wherein the decolourised terpene glycoside-containing solution comprises about 16% to about 75% mogroside V, on a dry weight basis.
17. The process of claim 14 , wherein the decolourised terpene glycoside-containing solution comprises about 30% to about 95% terpene glycosides, on a dry weight basis.