Field of Invention
The present invention relates to an improved process for the preparation of sesamin from sesame oil. Sesame seed is a rich source of lignans consisting mainly of sesamin and sesamolin. In different varieties of sesame seed, there is a change in the lignan composition as well as the presence of other lignans such as sesaminol, sesamol, episesaltin, and sesamolinol have also been reported. Apart from the antioxidant activity of lignans, other health benefits such as reduction of cholesterol, anti-cancer activity, lowering of blood pressure by some of the sesame lignans have also been reported in the literature. Therefore, sesame lignans can be used in health foods or as nutraceuticals to impart the good effects on health of consumers. In the present invention, sesame oil has been extracted with an organic polar solvent to get a lignan enriched oil and the resultant lignan enriched sesame oil has been processed further to prepare the main lignan product viz., sesamin. Accordingly, the lignan deficient sesame oil and sesamolin enriched fraction have been obtained as two by-products. The process can be carried out with minimal treatment of chemicals and with minimum machinery and is adaptable in the industry easily.
Background of the Invention and Description of Prior Art
Sesame seeds, used as an oilseed since ancient times, contain 25% protein and 50% oil, the latter having unique chemical-physiological activities (Budowski, P., and K.S. Markely, The chemical and physiological properties of sesame oil, Chem. Rev. 48:125-151 (1951).). Two major oil soluble lignans, sesamin and sesamolin, are considered responsible for the unique properties of sesame seed oil. Sesamin is known to reduce the absorption and biosynthesis of cholesterol in rats and plasma cholesterol in humans (Hirose,N., T. Inoue, K. Nishihara, M. Sugano, K. Akimoto, S. Shimizu, and H. Yamada, Inhibition of cholesterol absorption and synthesis in rats by sesamin, J. Lipid Res. 32:629-638 (1991).; Chen, P.R., K.L Chien, T.C. Su, C.J. Chang, T. Liu, H. Cheng, and C. Tsai, Dietary sesam reduces serum cholesterol and enhances antioxidant capacity in hypercholsterolemia, Nutr. Res. 25:559-567 (2005). Sesamin also elevates y-tocopherol levels in humans (Lemcke-Norojarvi, M., A. Kamal-Eldin, L.A. Appelqvist, L.H. Dimberg, M. Ohrvall, and B. Vessby, Corn and sesame oils increase serum y-tocopherol concentrations in healthy Swedish
women. J. Nutr. 131:1195-1201 (2001)). In addition, sesame seeds contain lignan glucosides, mainly sesaminol di- and triglucosides, sesamolinol diglucoside, and pinoresinol mono-, di-, and triglucosides which are concentrated in the defatted sesame flour [Moazzami, A., R.E. Andersson, and A. Kamal-Eldin, HPLC analysis of sesaminol glucosides in sesame seeds, J. Agric. Food. Chem. 54:633-638 (2006); Moazzami, A., R.E. Andersson, and A. Kamal-Eldin, Characterization and analysis of sesamolinol diglucoside in sesame seeds, Biosci. Biotechnol. Biochem. 70:1478-1481 (2006); Katsuzki, H., Kawasumi, S. Kawakishi, and T. Osawa, Structure of novel antioxidative lignan glucosides isolated from sesame seed, Biosci. Biotechnol. Biochem. 56:2087-2088 (1992)].
Sesaminol glucosides in defatted sesame flour can decrease susceptibility to oxidative stress [Kang, M., Y. Kawai, M. Naito, and T.Osawa, Dietary defatted sesame flour decreases susceptibility to oxidative stress in hypercholsterolemic rabbits, J. Nutr. 129:1885-1890 (1999)]. Other types of lignans are found in flaxseed, some vegetables, cereal brans, legumes and tea (Crosby, G., Lignans in food and nutrition, Food Technol. 59:32-36 (2005)). Sesame seeds contain an average of 0.63% of lignans mainly as sesamin, sesamolin, sesaminol and sesamolinol with the lowest and the highest lignan contents being 0.26% & 1.16% respectively [A.A. Moazzami, A. Kamal-Eldin, Sesame seed is a rich source of dietary lignans, J. Am. Oil Chem. Soc. 83(8):719-723 (2006)]. All the major lignans and lignan glucosides in sesame seeds contain a methylenedioxy bridge in their molecular structures, which is similar to a functional group found in many medicines [Yim, T.K., and K.M.Ko., Methylene dioxy group and cyclooctadiene ring as structural determinates of schisandrin in protecting against myocardial ischemia-reperfusion injury, Biochem. Pharmacol. 57:77-81(1999)].
In a study of the effects of microwave heating on stability of antioxidative components such as tocopherols and lignans and lipid quality of sesame seeds by Hiromi et al., concentrations of tocopherols, sesamin and sesamolin gradually decreased, and approximately 20% of these dominant components was lost after 30 min heating. However, with microwave treatments for 16 to 20 min, which would be optimal to prepare sesame oil with better quality, the sesame
seeds still retained over 85% of the antioxidative components and caused no significant chemical changes in lipids (Hiromi Yoshida, Goro Kajimoto, Microwave heating affects on.composition and oxidative stability of sesame (Sesamum indicum) Oil, J. Food Sci., 1994, 59 (3): 613-616).
Sesame Oil contain the following fatty acids: myristic (trace); palmitic (8.2%); stearic (3.6%); arachidic (1.1%); hexa decenic (0.5%); oleic (45.3%); linoleic (41.2%) [O.P. Mittal, Special chemical components of sesame oil, The Indian oils and oil seeds journal, 1956, 1(1). 38-41; Bandyopadhyay, K., Ghosh, M., and Ghosh, S., A comparative study on the physical and biochemical properties of sesame seed varieties and their corresponding meals, J. Oil Technol. Assn. India, 34:103-112, (2002)]. Among the minor components present are phytosterol and two other components, viz., sesamin and sesamolin, which are present in the unsaponifiable fraction of the oil and which are not found in any other vegetable oil. Sesamolin on hydrolysis gives sesamol.
A relatively simple chromatographic protocol was established to provide good separation of the unsaponifiable constituents from the seed oil of Sesamum indicum Linn. The protocol employs classical column chromatography using alumina and petroleum ether to collect furofuran lignans from sesame oil. Semipreparative RP-18 HPLC was used to separate the sesamin and sesamolin constituents in high purity (> 99%). The purity and identity of the separated compounds was confirmed by rechromatography using an analytical HPLC set up and GC-MS, respectively. The method described offers a means to isolate and collect sesamin and sesamolin in high purity for use as standards in furofuran lignan studies of sesame seed oil [Amarowicz, R., and Shahidi, F., and Pegg, R.B., Application of semipreparative RP18-HPLC for the purification of sesamin and sesamolin. J. Food Lipids,8:85-94(2001)].
On a study of the minor constituents of seed oils, sesamin has been isolated from a commercially available sample of expelled sesame oil and also from a solvent (carbon
tetrachloride) extracted sample employing Tocher's method. The average yield of sesamin from each sample was 0.2 percent on the weight of the oil (Iyer, B.H., and Narayanamurthy, N.L., Sesamin from sesame oil, The Oils and oilseeds journal, 1953, V. 100-101).
In the Yunani system of medicine, sesame oil is mentioned to be useful for many ailments including dry cough, asthma and diseases of the lungs. The work on sesamin by Iyer and Narayanamurthy et.al (Iyer, B.H., and Narayanamurthy, N.L., Sesamin from sesame oil, The Oils and oilseeds journal, 1953, V. 100-101) included a study of its pharmacological properties. While sesamin has shown little activity against the common pathogenic bacteria like Staphylococcus aureus, Streptococcus pyogenes, E.coli, it has indicated activity against Mycobacterium tuberculosis at even 1:1,000,000 dilution.
The Lignan composition of different varieties of sesame seeds has been reported by Moazzami, and Kamal-Eldin (Moazzami, A. A., and Kamal-Eldin, A., Sesame seed is a rich source of dietary lignans, J. Am. Oil Chem. Soc. 2006, 83(8). 719-723 ) which indicated the presence of four lignans in the different varieties of sesame seeds in the range of 469-897mg/100gram seeds. The levels of sesamin and sesamolin in the oils from four Sesamum species (Afaf Kamal-Eldin and Lars Ake Appelqvist, Variations in the composition of sterols, tocopherols and lignans in seed oils from four Sesamun species, J. Am. Oil Chem. Soc. 71(2):149-156 (1994)) reported by Kamal-Eldin and Appelqvist indicated a value of 0.02- 2.42%. Hemalatha and Ghafoorunissa (Hemalatha, S. and Ghafoorunissa. Lignans and tocopherols in Indian sesame cultivars, J. Am. Oil Chem. Soc. 2004, 81(5):467-470) reported sesamin and sesamolin contents in Indian commercial brands of sesame oils in the range of 0.65-1.41%.
Most of the literature and patents deal with the production of lignan glucosides from sesame seed and some others on production of sesame oil containing 1-3% of lignans by molecular distillation process and supercritical carbon dioxide extraction of sesame flavour. Further, the literature does not deal much with the processes on production of sesame lignans which are oil soluble such as sesamin and sesamolin.
Reference may be made to the patent JP2000210018A2 on obtaining an edible fat and oil having antioxidant effect by Kojima et al, wherein the process of preparation of an edible oil or fat useful for reducing peroxide concentration, containing tocopherol and or lignan has been obtained from sesame oil. This edible fat-and-oil is obtained by incorporating lignan-containing sesame oil with tocopherol and/or tocopherol-containing fat-and-oil; wherein it is preferable that the lignan content of this edible fat-and-oil is 0.01-1.0 wt.% and the weight ratio of the lignans to tocopherol is 1:(0.01-10). The drawbacks are that the oil or fat produced in the process has a concentration of lignan of maximum of 1.0%, while in the process of the present invention, the main product has a lignan content of 5-6% which is enriched 5-7 times as compared to that of the starting sesame oil. Probably Kojima et al have added purified lignans to give a concentration of 0.01-1.0% in sesame oil.
Reference may also be made to the work of Fukushima et al, in JP06200286A2, wherein they have developed a process for the production of a vegetable oil containing lignan by using cellulase enzyme and dispersing the sesame seed and enzyme followed by extraction using an organic solvent. This process is different from the one that has been carried out in the present invention because the starting materials namely sesame seeds and cellulase enzymes are used and the process is enzymatic reaction followed by solvent extraction, which is different from the present process of extracting the lignans from oil with organic solvent followed by further purification steps to prepare sesamin.
Reference may further be made to the work of Ishihara and Okada in JP10120695A2, wherein the efficient preparation of safe sesame lignans have been carried out by using molecular distillation of sesame oil. However, in the present process the inventors have used a safe solvent and extraction process for the production of a lignan concentrate having about 3% of sesamin in the concentrate followed by further purification to get sesamin (80%) powder. The cited process of Ishihara and Okada is different technique wise and also is a thermal process, which may decompose lignans.
Thus, keeping in view the hitherto known prior art it may be summarized that there is no patent or procedure reported in the literature on the preparation of pure lignans (mixture of sesamin arid sesamolin) by first enriching the sesame oil using organic solvent extraction followed by crystallization to obtain pure mixture of sesamin and sesamolin, which are useful for food and pharmaceutical applications. No unwanted chemicals are present in the purified lignan mixture of the present invention, predominantly containing sesamin along with small amounts of sesamolin, unlike in chromatographic procedures followed for removal of triglycerides before being subjected to further purification steps.
Objects of the Invention
The main object of the present invention is thus to provide an improved process for the production of sesamin from sesame oil, which obviates the drawbacks of the hitherto known prior art.
Another object of the invention is to provide a process wherein the sesamin present at 0.5% level in the sesame oil has been enriched to 3.5-4.0% in the oil by first extracting the sesame oil with an organic solvent followed by purification to obtain sesamin with a purity of 80%, which can be straight away used in foods for providing health benefits.
Still another object of the invention is to provide a process wherein the process of preparation of sesamin from sesame oil is simple, involves less number of unit operations and can be performed in the sesame oil industry with minimum additional facility.
Yet another object of the invention is to provide a process wherein the solvents permitted in food industry are used for extraction and can be recovered ahd reused. Hence, the sesamin produced by the present process can be used safely for food and pharmaceutical applications.
A further object of the invention is to provide a process wherein the sesamin powder obtained can be easily dissolved in edible vegetable oils and hence is more effective than antioxidant extracts.
Summary of the Invention
The present invention provides an improved process for the preparation of sesamin from sesame oil, which comprises mixing of the sesame oil with ethanol to extract lignans into the ethanol layer followed by separation of the ethanol layer and removal of solvent to get a lignan enriched sesame oil which is conditioned and then crystallized in hexane to get sesamin.
Sesame oil (expeller pressed/crude oil) is mixed with alcoholic solvent and mixed. The mixture is allowed to settle resulting in the formation of two layers, which are desolventized separately in a flash evaporator. The top alcohol layer contains lignan enriched sesame oil while the bottom oil layer contains the spent sesame oil, which is low in lignans. The bottom layer can be used as refined sesame oil as it has less of FFA and less of sesame flavour.
The lignan enriched sesame oil is further treated with a hydrocarbon solvent and mixed followed by cooling. Then the contents are decanted carefully through a filter paper retaining all the solidified mass inside the flask. The contents in the flask are again treated with the hydrocarbon solvent, swirled to mix the contents and cooled again. Then the complete contents are transferred on to the previously used filtered filter paper and the filtrate allowed to collect separately. The solid on the filter paper is washed once with additional hydrocarbon solvent and the contents allowed to dry on the filter. After all the residual solvent has evaporated from the filter paper, the solid material is recovered, which is sesamin. The filtrate from the above step is desolventized to get sesamolin enriched sesame oil.
Accordingly, the present invention provides an improved process for the preparation of sesamin from sesame oil, comprising the steps of:
[a] mixing of sesame oil with an alcoholic solvent having carbon chain length in the range of CI to C3 at a temperature in the range of 15 to 80 degree C for 5 to 60 minutes to obtain an oil alcohol oil mixture;
[b] allowing the oil solvent mixture as obtained in step [a] to settle for 30 min to obtain a top layer and bottom layer;
[c] separating the top layer as obtained in step [b] and removing the solvent to obtain a lignan enriched sesame oil;
[d] heating the lignan enriched sesame oil as obtained in step [c] at a temperature of 95 degree C followed by cooling to 30 degree C;
[e] crystallization of sesamin by mixing the heated lignan enriched sesame oil as obtained in step [d] with a hydrocarbon solvent having carbon chain length in the range of C5 to C7 followed by cooling to -20 to +40 degree C;
[f] filtering the mixture as obtained in step [e] to collect the filtrate and residue separately;
[g] washing the residue as obtained in step [f] with the said hydrocarbon solvent followed by drying to obtain the desired sesamin powder;
[h] optionally, desolventizing the filtrate as obtained in step [f] to obtain the sesamolin enriched sesame oil
Brief Description of the Accompanying Drawings
Figure 1 illustrates the flow chart describing the major steps involved in the process of the present invention.
Detailed Description of the Invention
The present invention provides an improved process for the preparation of sesamin from sesame oil, which comprises mixing of the sesame oil with ethanol at room temperature to extract lignans into the ethanol layer followed by separation of the ethanol layer and removal of solvent to get a lignan enriched sesame oil which is conditioned and then crystallized in hexane to get sesamin powder.
The preliminary step of extraction of lignans has been standardized and the conditions are: an alcohol as the solvent for making the sesame oil enriched with lignans, wherein the alcohol is having carbon chain length in the range of CI to C3, wherein the oil to solvent ratio being 1:1 to 1:20, at temperature of 15 degree C to 85 degree C which is the boiling temperature of the solvent; mixing speed of 250rpm and a duration of 5 to 60 minutes. This results in an oil enriched with 5-6 times the lignans found in starting sesame oil. The production of lignan enriched sesame oil using these conditions is not reported anywhere in the prior art.
Further, the step of crystallization of sesamin from lignan enriched sesame oil using a hydrocarbon solvent is performed, wherein the ratio of lignan enriched sesame oil to the hydrocarbon solvent is in the range of 1:1 to 1:20, preferably in the ratio of 1:3 and wherein the hydrocarbon solvent used is having carbon chain length in the range of C5 to C7. It may eb noted that unless the oil is enriched in lignans, one cannot crystallize sesamin and hence the first step of concentration of lignans using a polar solvent is very crucial and important and hence novel. Crystallization of sesamin from lignan enriched sesame oil using a hydrocarbon solvent is new and also non-obvious.
From the above steps, it is possible to produce >80% pure lignans having 80-90% sesamin and 10-20% sesamolin with a melting point of 120-125 degree C. This is another novel aspect in the production of pure sesamin from sesame oil.
There is no procedure or patent reported in the literature on preparation of pure lignans (mixture of sesamin and sesamolin) by first enriching the sesame oil using organic solvent extraction(polar or non-polar solvent) followed by crystallization to obtain pure mixture of sesamin and sesamolin (using polar or non-polar solvent), which is novel. The products obtained can directly be made use of in the food and pharmaceutical industries as no unwanted chemicals are present in the purified lignan mixture predominantly containing sesamin along

with small amounts of sesamolin unlike in chromatographic procedures followed for removal of triglycerides before subjected to further purification steps.
In an embodiment of the present invention, the extraction solvent is absolute ethanol or any other alcohol of carbon chain length Cl-3.
In another embodiment of the present invention, the solvent ratio is 1:1 to 1:20, preferably 1:10.
In yet another embodiment of the present invention, the temperature of extraction is 27?C which is the room temperature. However, the extraction can be performed in the range of 15-805C.
In still another embodiment of the present invention, the extraction period can be in the range of 5-60minutes, preferably 15minutes.
In yet another embodiment of the present invention, the mixing speed can vary from 100-600 RPM, but preferably is 170-250RPM.
In still another embodiment of the present invention, the solvent used for crystallization of sesamin is preferably hexane. However, any hydrocarbon solvent of carbon chain length C5-C7 selected from the group consisting of petroleum ether, pentane, hexane, and heptane may be used.
In yet another embodiment of the present invention, the solvent ratio of hexane to lignan enriched sesame oil is 1:5 for the crystallization of sesamin.
In another embodiment of the present invention, the crystallization of sesamin from lignan enriched sesame oil-hexane mixture can be performed at a temperature in the range of-20QC to +409C, preferably 59C.
EXAMPLES The following examples are given by way of illustration of the present invention and therefore should not be constructed to limit the scope of the present invention.
Example 1
The effect of solvent chain length on extractability of lignans from sesame oil was tested by taking lg of oil in 20milliliter capacity stoppered test tubes and adding 1, 5, 10, 20 milliliters of methanol, ethanol, n-propanol and iso-propanol and stirring vigorously using a vortex mixer for 15 minutes. The tubes were then allowed to stand for 30 minutes and later the top layer (solvent layer) was decanted, desolventised and estimated for lignans content in the extract. The data in Table 1 show that ethanol being the best solvent for extraction and a ratio of 1:10 was considered feasible for the extraction purposes.
Example 2
The effect of solvent ratio on extractability of lignans from sesame oil was tested by taking lg of oil in 20milliliter capacity stoppered test tubes and adding 1, 2, 5, 10, 15, 20 milliliters of ethanol, and stirring vigorously using a vortex mixer for 15 minutes. The tubes were then allowed to stand for 30 minutes and later the top layer (solvent layer) was decanted, desolventised and estimated for lignans content in the extract. The data in Table 2 show that a ratio of 1:1-1:5 were too low and 1:20 was considered too high and a ratio of 1:10 was taken as optimum for carrying out the extraction work. The solvents such as methanol being poisonous, and propanol not showing preferential extraction were abandoned from further experiments.
Example 3
The effect of temperature on extractability of lignans from sesame oil using ethanol as the extraction solvent was tested by taking lg of oil in 20milliliter capacity stoppered test tubes and adding lOmilliliters of solvent followed by vortexing at 15C, 25-27C, 50C, 80C in suitable baths
maintained at those temperatures for 15minutes. Afterwards, the contents brought to room temperature and the supernatant solvent layer which contains the lignans was examined for lignans extractability. The data in Table 3 show that temperatures of 15-80 did not have much difference in extractability of lignans indicating no influence of temperature of extraction and hence the experiments were restricted to room temperature extraction.
Example 4
25g sesame oil samples were taken in beakers(500 millilitres capacity/lLitre capacity) and added different weight/volume ratio of solvent of 25, 50, 125, 250, 375 and 500 millilitres of ethanol and stirred at 250RPM for 15 minutes at 279C. Afterwards, the resultant oil ethanol mixture was allowed to settle for 30minutes and then decanted the supernatant ethanol layer into another flask. Separated the remaining oil and ethanol layers using a separatory funnel. The two fractions were separately desolventized in a flash evaporator at 40 degree C at 75 mbar pressure. The supernatant alcohol layer and the bottom spent oil layers after desolventization yielded lignan enriched sesame oil (3g) and sesame oil low in lignans(22g) respectively. The data is shown in Table 4.
Example 5
25g sesame oil sample was taken in a beaker (500 millilitres capacity) and added 250 millilitres of ethanol and stirred at 250RPM for 15 minutes at different temperatures of 15, 25-27, 50 and 809C using temperature controlled water bath. Afterwards, the resultant oil ethanol mixture was brought to room temperature and then allowed to settle for 30minutes and afterwards, decanted the supernatant ethanol layer into another flask. Separated the remaining oil and ethanol layers using a separatory funnel. The two fractions were separately desolventized in a flash evaporator at 40 degree C at 75 mbar pressure. The supernatant alcohol layer and the bottom spent oil layers after desolventization yielded lignan enriched sesame oil (2-4g) and sesame oil low in lignans(20-22g) respectively. The data is shown in Table 5.
Example 6
25g sesame oil samples were taken in beakers (500 millilitres capacity) and added 250 millilitres of ethanol and stirred at 250RPM for different mixing times of 5,15, 30, 45, and 60 minutes at 272C. Afterwards, the resultant oil ethanol mixture was allowed to settle for 30minutes and then decanted the supernatant ethanol layer into another flask. Separated the remaining oil and ethanol layers using a separatory funnel. The two fractions were separately desolventized in a flash evaporator at 40 degree C at 75 mbar pressure. The supernatant alcohol layer and the bottom spent oil layers after desolventization yielded lignan enriched sesame oil (2-3g) and sesame oil low in lignans(20-22g) respectively. The data is shown in Table 6.
Example 7
The lignan enriched sesame oil was taken in a flat bottom flask and then heated to 95C to dissolve any crystallized sesamin for uniform sampling and then cooled to 30 degree C followed by taking 5.8g and then treated with 52 milliliters of different chain length solvents, pentane(C5), hexane(C6), and heptanes(C7) and mixed by swirling in hand and then the flask stoppered and cooled at 5 degree C for 48hours. Then the contents were decanted carefully through a filter paper retaining all the solidified mass inside the flask. The contents in the flask were again treated with 13 milliliters of pentane, or hexane or heptane, swirled to mix the contents and cooled again at 5C for 2hours. Then the complete contents were transferred on to the previously filtered filter paper and the filtrate allowed to collect separately. The solid on filter paper was washed once with additional 13milliliters volume of cold pentane, or hexane or heptane (5 degree C) and the contents allowed to dry on the filter. After all the residual solvent from different solvent crystallisation has evaporated from the filter paper, the solid materials were recovered and weighed (200-313.6mg) which was sesamin. The filtrate from the above step was desolventized to get sesamolin enriched sesame oil (11-11.6g). The data is presented in Table 7.
Example 8
The lignan enriched sesame oil was taken in a flat bottom flask and then heated to 95C to dissolve any crystallized sesamin for uniform sampling and then cooled to 30 degree C followed by taking 5.8g and then treated with 52 milliliters of hexane and mixed by swirling in hand and then the flask stoppered and cooled at 5 degree C for 48hours. Then the contents were decanted carefully through a filter paper retaining all the solidified mass inside the flask. The contents in the flask were again treated with 13 milliliters of hexane, swirled to mix the contents and cooled again at 5C for 2hours. Then the complete contents were transferred on to the previously filtered filter paper and the filtrate allowed to collect separately. The solid on filter paper was washed once with additional 13milliliters volume of cold hexane (5 degree C) and the contents allowed to dry on the filter. After all the residual solvent has evaporated from the filter paper the solid material was recovered and weighed (313.6mg) which was sesamin. The filtrate from the above step was desolventized to get sesamolin enriched sesame oil (11.6g). The data is presented in Table 8.
Example 9
The lignan enriched sesame oil was taken in a flat bottom flask and then heated to 95C for 30 minutes to dissolve any crystallized sesamin for uniform sampling and then cooled to 30 degree C followed by taking 5.8g and then treated with 52 milliliters of hexane and mixed by swirling in hand and then the flask stoppered and cooled at 5 degree C for 48hours. Then the contents were decanted carefully through a filter paper retaining all the solidified mass inside the flask. The contents in the flask were again treated with 13 milliliters of hexane, swirled to mix the contents and cooled again at 5C for 2hours. Then the complete contents were transferred on to the previously filtered filter paper and the filtrate allowed to collect separately. The solid on filter paper was washed once with additional 13milliliters volume of cold hexane (5 degree C) and the contents allowed to dry on the filter. After all the residual solvent has evaporated from the filter paper the solid material was recovered and weighed (313.6mg) which was sesamin. The filtrate from the above step was desolventized to get sesamolin enriched sesame oil (11.6g). The data is presented in Table 9
Example 10
25g or 200g sesame oil sample (commercial oil sample 1) was taken in a beaker (500 milliliter or 2Litre capacity) and added 250milliliters or 2Litre of absolute ethanol and stirred at 250RPM for 15 minutes at 272C. Afterwards, the resultant oil ethanol mixture was allowed to settle for 30minutes and then decanted the supernatant ethanol layer into another flask. Separated the remaining oil and ethanol layers using a separatory funnel. The two fractions were separately desolventized in a flash evaporator at 40 degree C at 75 mbar pressure. The supernatant alcohol layer and the bottom spent oil layers after desolventization yielded lignan enriched sesame oil (3.4g or 30g) (Table 10) and sesame oil low in lignans(21g or 168g)(Table 12) respectively. The data is shown in Tables 10 & 12.
The lignan enriched sesame oil was taken in a flat bottom flask and then heated to 95C for 30 minutes to dissolve any crystallized sesamin for uniform sampling and then cooled to 30 degree C followed by taking 13g and then treated with 52 milliliters of hexane and mixed by swirling in hand and then the flask stoppered and cooled at 5 degree C for 48hours. Then the contents were decanted carefully through a filter paper retaining all the solidified mass inside the flask. The contents in the flask were again treated with 13 milliliters of hexane, swirled to mix the contents and cooled again at 5C for 2hours. Then the complete contents were transferred on to the previously filtered filter paper and the filtrate allowed to collect separately. The solid on filter paper was washed once with additional 13milliliters volume of cold hexane (5 degree C) and the contents allowed to dry on the filter. After all the residual solvent has evaporated from the filter paper the solid material was recovered and weighed (313.6mg) which was sesamin. The filtrate from the above step was desolventized to get sesamolin enriched sesame oil (11.6g). The data is presented in Table 11.
Example 11
25g or 200g sesame oil sample (commercial oil sample 2) was taken in a plastic container (500milliliters or 2Litre capacity) and added 250milliliters or 2 Litre of absolute ethanol and stirred at 250RPM for 15minutes at 27 degree C. Afterwards, the resultant oil ethanol mixture
was allowed to settle for 30minutes and then decanted the supernatant ethanol layer into another flask. Separated the remaining oil and ethanol layers using a separatory funnel. The two fractions were separately desolventized in a flash evaporator at 40 degree C at 75mbar pressure. The supernatant alcohol layer upon desolventization yielded lignan enriched sesame oil (2.7g or 21g) (Table 10) while the lower layer has spent sesame oil along with small amount of alcohol, which was recovered by desolventization to yield sesame oil low in lignans (spent oil)(21g or 175g) and the recovered solvent for reuse (Table 12). The data is shown in Tables 10 &12.
The lignan enriched sesame oil (13.52g) was taken in a flat bottom flask and then heated to 95 degree C for 30 minutes to dissolve any crystallized sesamin for uniform sampling and then cooled to 30 degree C followed by taking 13.52g and then treated with 54 milliliters of hexane and mixed by swirling in hand and then the flask stoppered and cooled at 5 degree C for 48hours. Then the contents were decanted carefully through a filter paper retaining all the solidified mass inside the flask. The contents in the flask were again treated with 14 milliliters of hexane, swirled to mix the contents and cooled again at 5 degree C for 2hours. Then the complete contents were transferred on to the previously filtered filter paper and the filtrate was allowed to collect separately. The solid on filter paper was washed once with additional 14milliliters of cold hexane (5 degree C) and the contents allowed to dry on the filter. After all the residual solvent had evaporated from the filter paper, the solid material was recovered and weighed (498.9mg) which was sesamin. The filtrate from the above step was desolventized to get sesamolin enriched sesame oil (11.6g) (Table 11).
The by-products of the process are sesame oil (low in lignans: 84%); sesamolin enriched fraction (13.5%) having strong sesame flavour. The data is presented in Tables 12 & 13.

TABLES
Table 1. Effect of alcohol solvent chain length on lignan extraction and recovery

(Table Removed) (Extraction temperature: Room temperature, 25-27C)
Table 2. Effect of solvent ratio on lignans extraction and recovery

(Table Removed) (Extraction temperature: Room temperature, 25-27C)
Table 3. Effect of temperature of extraction on lignans extraction and recovery

(Table Removed) (Oil to solvent ratio is fixed at 1:10 w/v)
Table 4. Effect of solvent ratio on lignans extraction and recovery (25g oil batches)

(Table Removed) Table 5. Effect of temperature on extraction of lignans and recovery (25g oil batches)

(Table Removed)Table 6. Effect of mixing time on lignan extraction and recovery (25 g oil batches)

(Table Removed)Table 7. Effect of hydrocarbon solvent chain length on sesamin yield

(Table Removed)
Table 8. Effect of solvent ratio on sesamin yield

(Table Removed)48 hours)
Table 9. Effect of temperature of crystallization on sesamin yield

(Table Removed) (Duration of crystallization: 48hours) Table 10. Lignans content and recovery values of lignans enriched oil prepared from two brands of commercial sesame oil(25g and 200g batches)

(Table Removed)
Table 11. Sesamin content and composition of sesamin product

(Table Removed) Melting point of sesamin: 120-1253C; (1232C*),
El%lcm at 288nm = 224.3 (pure sesamin, 230.1 in hexane-chloroform, 7:3v/v) E23.03** in iso-octane at 287nm[(*literature values,(Budowski, P., Sesame Oil III. Antioxidant Properties of Sesamol, J. Amer. Oil Chem. Soc, :264-267,1950); **Budowski, P., O'Connor, R.T., and Field, E.T., Sesame oil VI. Determination of sesamin, J. Amer. Oil Chem. Soc, 51-55, (1951)]
Table 12. Oil recovered and its lignans content (25g and 200g batches)

(Table Removed) Table 13. Oil recovered and its lignan content after crystalisation of sesamin (sesamolin enriched fraction) from two brands of sesame oil
(Table Removed)
The main advantages of the present invention are:
> The sesamin present at 0.5% level in sesame oil has been enriched to 3.5-4.0% in the oil by first extracting the sesame oil with an organic solvent followed by purification to obtain sesamin with a purity of 80% which can be straight away used in foods for providing health benefits.
> The sesamin powder can be easily dissolved in edible vegetable oils and hence is expected to be more effective than antioxidant extracts.
> The process of preparation of sesamin from sesame oil is simple, less number of unit operations and can be performed in the sesame oil industry with minimum additional facility.
> The solvents used for extraction are allowed in food industry and can be recovered and reused. Hence, the sesamin produced in this process can be used safely for food and pharmaceutical applications.

We claim:
1. An improved process for the preparation of sesamin from sesame oil, comprising the
steps of:
[a] mixing of sesame oil with an alcoholic solvent having carbon chain length in the range of CI to C3 at a temperature in the range of 15 to 80 degree C for 5 to 60 minutes to obtain an oil alcohol oil mixture;
[b] allowing the oil solvent mixture as obtained in step [a] to settle for 30 min to obtain a top layer and bottom layer;
[c] separating the top layer as obtained in step [b] and removing the solvent to obtain a lignan enriched sesame oil;
[d] heating the lignan enriched sesame oil as obtained in step [c] at a temperature of 95 degree C followed by cooling to 30 degree C;
[e] crystallization of sesamin by mixing the heated lignan enriched sesame oil as obtained in step [d] with a hydrocarbon solvent having carbon chain length in the range of C5 to C7 followed by cooling to -20 to +40 degree C;
[f] filtering the mixture as obtained in step [e] to collect the filtrate and residue separately;
[g] washing the residue as obtained in step [f] with the said hydrocarbon solvent followed by drying to obtain the desired sesamin powder;
[h] optionally, desolventizing the filtrate as obtained in step [f] to obtain the sesamolin enriched sesame oil.
2. A process as claimed in claim 1, wherein the extraction solvent is preferably absolute ethanol.
3. A process as claimed in claim 1, wherein the oil to solvent ratio is in the range of 1:1 to 1:20, preferably 1:10.
4. A process as claimed in claim 1, wherein extraction is preferably done at a temperature of 27 degree C for 15 minutes.
5. A process as claimed in claim 1, wherein the mixing speed is 100-600 RPM, preferably 170-250RPM.
6. A process as claimed in claim 1, wherein the hydrocarbon solvent used for crystallization of sesamin is selected from the group consisting of petroleum ether, pentane, hexane, and heptane.
7. A process as claimed in claim 1, wherein the hydrocarbon solvent used for crystallization of sesamin is preferably hexane.
8. A process as claimed in claim 1, wherein the ratio of hydrocarbon solvent to lignan enriched sesame oil is in the range of 1:1 to 1:20, preferably 1:3.
9. A process as claimed in claim 1, wherein the temperature of crystallization of sesamin from lignan enriched sesame oil-hexane mixture is preferably 5 degree C.
10. An improved process for the preparation of sesamin from sesame oil substantially as herein described with reference to the foregoing examples and drawings accompanying the specification.