FIELD OF THE INVENTION

The invention relates to a process for purification of high purity mogrosides fromSiraitia grosvenorifruit extract, particularly high purity mogrosides mixtures with high mogroside V content, and further to high purity mogrosides and their applications in food and beverage products.

DESCRIPTION OF THE RELATED ART

Luo han guo generally refers to a fruit ofSiraitia grosvenori, a member of the Cucurbitaceae family, is a plant native to some regions of southern Asia and China. The sweet taste of luo han guo mainly comes from triterpene glycosides generally known as mogrosides or mogrol glycosides. Mogrosides comprise only about 1% of the luo han guo fruit. There are a number of mogrosides identified in luo han guo but generally mogroside V (CAS No: 88901-36-4) has the highest concentration compared to others (Table 1). Mogrol glycosides have the same core molecule—mogrol or oxo-mogrol and differ from each other by number and type of glycosidic residues bonded to mogrol or oxo-mogrol molecules.

TABLE 1Mogrosides present in Luo han guo fruitsSubstanceMol. FormulaMol. WeightMogroside IIEC42H72O14801.01Mogroside IIIC48H82O19963.15Mogroside IVC54H92O241125.29Mogroside VC60H102O291287.43Mogroside VIC66H112O341449.5811-oxo-Mogroside VC60H100O291285.42Siamenoside IC54H92O241125.29Grosmomoside IC54H92O241125.29

Various extraction techniques are used to isolate mogrosides from luo han guo fruits. As a result luo han guo powdered extracts are being prepared which usually contain 30-65% w/w of total mogrosides, and mogroside V content of those materials can vary as much as 18-55%. Such extracts generally cannot be used as a sweetener in foods and beverages as they contain substantial amount of impurities; some of the impurities possess undesirable organoleptic properties, thus affecting the color, flavor, odor and taste profile of luo han guo extract.

Non-limiting examples of such impurities include proteins, pigments, polysaccharides, aldehydes, unsaturated aldehydes, methyl ketones, butyl crotonate, and phenolic compounds.

Hence there is a need for a commercially viable process for enhancing mogrosides content, particularly mogroside V content from low purity luo han guo preparations and removing the undesirable impurities so as to significantly improve the organoleptic characteristics of luo han guo preparations and thus allowing their usage in food.

No techniques are currently available for purifying of low purity luo han guo extract into high purity mogrosides. Therefore, there is a need for a process of for purification of high purity mogrosides fromSiraitia grosvenorifruit extract.

SUMMARY OF THE INVENTION

The invention relates to a process for preparation of high purity mixtures of mogrosides fromSiraitia grosvenorifruit extract.

In one embodiment, the process for preparation of highly purified mogrosides mixture from low purity mogrosides mixture comprises:

a. providing a mixture of low purity mogrosides;

b. dissolving the low purity mogrosides mixture in water or an aqueous alcohol solution to form an initial solution of mogrosides;

c. passing the initial solution through a column system, wherein the column system comprises a plurality of columns, and each column is packed with a sorbent having different affinities to impurities and mogrosides so that one or more columns retains more mogrosides than other columns;

d. washing the columns to remove impurities with an acidic aqueous solution, a basic aqueous solution, and an aqueous alcoholic solution successively;

e. eluting the columns with an aqueous alcohol solution that contains higher alcohol content than the aqueous alcohol solution used in the washing step, wherein the eluate from the columns with high content of mogrosides are combined; and

f. drying the combined eluate to obtain high purity mogrosides with the content of the total mogrosides are more than 70% (w/w).

In another embodiment of the process, in the washing step (d), the water to alcohol ratio (vol/vol) in the aqueous alcoholic solution is 99.9:0.1 to 60:40, and wherein in the eluting step (e), the water to alcohol ratio (vol/vol) of the aqueous alcoholic solution is 60:40 to 0.1:99.9.

In another embodiment of the process, in the washing step (d), the acidic aqueous solution comprises HCl, and the basic aqueous solution comprises NaOH.

In another embodiment of the process, the aqueous alcoholic solution comprises alcohol that is selected from the group consisting of methanol, ethanol, n-propanol, 2-propanol, 1-butanol, and 2-butanol.

In another embodiment of the process, the sorbent is a macroporous polymeric adsorption resin capable of adsorbing mogrosides.

In another embodiment of the process, the plurality of columns are consecutively connected.

In another embodiment of the process, the plurality of columns are connected in parallel.

In another embodiment of the process, it further comprises:

g. dissolving the high purity mogrosides in water or an aqueous alcoholic solution to result in a solution of mogrosides;

h. passing the solutions of mogrosides through a sequence of ultrafiltration and/or nanofiltration membranes with MWCO size from 1000 to 2500 to increase the purity of mogrosides mixture (total mogrosides content, % dry basis); and

i. drying the obtained mogrosides mixture solution to obtain highly purified mogrosides mixture.

The present invention further provides a sweetener mixture comprising the high purity mogrosides; wherein the high purity mogrosides are blended with another high intensity sweetener.

In one embodiment of the sweetener mixture, the another high intensity sweetener is selected from the group consisting of steviol glycosides including a purified sweet steviol glycoside mixture, stevioside, rebaudioside A, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside E, rebaudioside F, dulcoside A, dulcoside B, rubusoside, and stevia; siamenoside; mogroside IV; mogroside V; Luo Han Guo sweetener; monatin and its salts (monatin SS, RR, RS, SR); glycyrrhizic acid and its salts; curculin; thaumatin; monellin; mabinlin; brazzein; hernandulcin; phyllodulcin; glycyphyllin; phloridzin; trilobatin; baiyunoside; osladin; polypodoside A; pterocaryoside A; pterocaryoside B; mukurozioside; phlomisoside I; periandrin I; abrusoside A; cyclocarioside I; and combinations thereof.

The present invention also provides a product comprising the high purity mogrosides.

In one embodiment of the product, the product is selected from the group consisting of food, beverage, pharmaceutical composition, tobacco, nutraceutical, oral hygienic composition, or cosmetic.

One objective of the invention to develop an efficient method of preparation of highly purified mogrosides' mixture from low purity mogrosides' mixture.

Another objective of the invention is to develop a method of preparation of high mogroside V content luo han guo sweetener from low mogroside V content luo han guo sweetener.

