Sweetening compositions and processes for preparing them

Abstract

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 - 22 . (canceled) 
     
     
         23 . 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 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) separating melanoidins from terpene glycosides in the solution to obtain a decolourised terpene glycoside-containing solution.   
     
     
         24 . A process according to  claim 23 , further comprising drying the decolourised terpene glycoside-containing solution obtained from step (e) to form a powdered composition. 
     
     
         25 . A process according to  claim 24 , wherein the decolourised terpene glycoside-containing solution is concentrated before drying. 
     
     
         26 . A process according to  claim 23 , wherein the fresh plant source material is a fruit of the Cucurbitaceae family. 
     
     
         27 . A process according to  claim 23 , wherein the fresh plant source material is Luo Han Guo fruit. 
     
     
         28 . A process according to  claim 27 , 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 Luo Han Guo fruit. 
     
     
         29 . A process according to  claim 28 , wherein the triterpene glycosides are extracted from the Luo Han Guo fruit using counter current extraction. 
     
     
         30 . A process according to  claim 23 , wherein the extract is clarified in step (b) by ultrafiltration. 
     
     
         31 . A process according to  claim 23 , wherein the clarified extract obtained from step (b) is filtered, centrifuged or decanted before step (c). 
     
     
         32 . A process according to  claim 23 , wherein the concentrating of terpene glycosides comprises (i) contacting the clarified extract with an adsorbent resin, wherein the adsorbent resin binds terpene glycosides in the clarified extract; and (ii) eluting terpene glycosides from the adsorbent resin to obtain a purified terpene glycoside-containing solution. 
     
     
         33 . A process according to  claim 32 , wherein the adsorbent resin is a macroporous polymeric adsorbent resin. 
     
     
         34 . A process according to  claim 32 , wherein the adsorbent resin is a styrene divinylbenzene copolymer or a divinylbenzene copolymer resin. 
     
     
         35 . A process according to  claim 32 , wherein step (c) is carried out in a pressurised vessel. 
     
     
         36 . A process according to  claim 32 , wherein the terpene glycosides are eluted from the adsorbent resin with an aqueous solution of ethanol to produce a terpene-glycoside containing ethanol solution. 
     
     
         37 . A process according to  claim 36 , wherein the elution comprises a plurality of elution steps using ethanol solutions of increasing ethanol concentration. 
     
     
         38 . A process according to  claim 36 , wherein the heating step (d) comprises heating the terpene-glycoside containing ethanol solution to both promote formation of melanoidins and evaporate ethanol, thereby allowing recovery of the ethanol. 
     
     
         39 . A process according to  claim 23 , wherein step (d) comprises heating the purified terpene glycoside-containing solution to a temperature of about 80° C. to about 120° C., for a period of time sufficient to form melanoidins. 
     
     
         40 . A process according to  claim 39 , wherein the heating is carried out at a temperature of about 80° C. to about 100° C., for a period of time of about 120 minutes to about 45 minutes. 
     
     
         41 . A process according to  claim 23 , wherein the decolourising in step (e) comprises contacting the terpene glycoside and melanoidin-containing solution from step (d) with a decolourising resin which binds the melanoidins, to obtain a decolourised terpene glycoside-containing solution. 
     
     
         42 . A process according to  claim 41 , wherein the decolourising resin comprises a highly porous, macroporous, type I, strongly basic anion resin. 
     
     
         43 . A process according to  claim 41 , wherein step (e) is carried out in a pressurised vessel. 
     
     
         44 . A process of preparing a sweetening composition from a fresh plant source material containing terpene glycosides, the process comprising:
 (a) heating a terpene glycoside-containing solution obtained by extracting terpene glycosides from the fresh plant source material to a sufficient temperature and for a sufficient time to form melanoidins; and   (b) separating the melanoidins from the terpene glycosides in the extract to obtain a decolourised terpene glycoside-containing solution.   
     
     
         45 . A process according to  claim 44 , wherein the fresh plant source material is Luo Han Guo fruit, and wherein the terpene glycoside-containing solution used in step (a) is obtained by an extraction process comprising:
 contacting macerated Luo Han Guo fruit with hot water, at a sufficient time and for a sufficient temperature to extract triterpene glycosides and produce a terpene glycoside-containing solution from the fruit, and   clarifying the terpene glycoside-containing solution.   
     
     
         46 . A process according to  claim 45 , wherein the contacting is carried out using countercurrent extraction. 
     
     
         47 . A process according to  claim 45 , wherein the clarifying comprises ultrafiltration of the terpene glycoside-containing solution. 
     
     
         48 . A process according to  claim 45 , wherein step (b) comprises contacting the terpene glycoside-containing solution heated in step (a) with a decolourising resin that binds melanoidins. 
     
     
         49 . A process according to  claim 45 , wherein the terpene glycoside-containing solution heated in step (a) is obtained by a process further comprising concentrating terpene glycosides in the terpene glycoside-containing solution after clarifying. 
     
     
         50 . A process according to  claim 49 , wherein the concentrating comprises (i) contacting the clarified terpene glycoside-containing solution with an adsorbent resin, wherein the adsorbent resin binds terpene glycosides in the terpene glycoside-containing solution; and (ii) eluting terpene glycosides from the resin to obtain a purified terpene glycoside-containing solution. 
     
     
         51 . A process according to  claim 50 , wherein the adsorbent resin is a macroporous polymeric adsorbent resin. 
     
     
         52 . A process according to  claim 45 , further comprising drying the decolourised terpene glycoside-containing solution obtained from step (b) to form a powdered composition. 
     
     
         53 . A sweetening composition obtained by a 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 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) separating melanoidins from terpene glycosides in the solution to obtain a decolourised terpene glycoside-containing solution.   
     
     
         54 . A food product or a beverage comprising the sweetening composition of  claim 53 . 
     
     
         55 . A sweetening composition obtained by a process comprising:
 (a) heating a terpene glycoside-containing solution obtained by extracting terpene glycosides from a fresh plant source material to a sufficient temperature and for a sufficient time to form melanoidins; and   (b) separating the melanoidins from the terpene glycosides in the extract to obtain a decolourised terpene glycoside-containing solution.   
     
     
         56 . A food product or a beverage comprising the sweetening composition of  claim 55 . 
     
     
         57 . A process according to  claim 30 , wherein the extract is clarified by ultrafiltration using an ultrafiltration membrane of between 50,000-100,000 daltons. 
     
     
         58 . A process according to  claim 23 , wherein the fresh plant source material is Luo Han Guo fruit, and wherein step (a) comprises shredding or crushing the Luo Han Guo fruit, and contacting the shredded or crushed Luo Han Guo fruit with hot water at a temperature greater than about 80° C. to inactivate protease in the Luo Han Guo fruit. 
     
     
         59 . A process according to  claim 48 , wherein the contacting of the terpene glycoside-containing solution heated in step (a) with the decolourising resin further binds non-terpene glycoside molecules in the solution. 
     
     
         60 . A process according to  claim 50 , wherein the adsorbent resin is a styrene divinylbenzene copolymer or a divinylbenzene copolymer resin.