Journal of Scientific & Industrial Research
Vol. 63, July 2004, pp. 569-578

Gamma-oryzanol from rice bran oil – A review

M Patel and S N Naik*

Center for Rural Development and Technology, Indian Institute of Technology, New Delhi 110 016

Received: 06 February 2004; accepted: 10 May 2004

 

Scheme 1¾Shows cycloartenyl ferulate, 24-methylene­cyclo­artanyl ferulate and campesteryl ferulate the three major components

Rice bran oil is unique among edible oil due to its rich source of commercially and nutritionally important phytoceuticals such as, oryzanol, lecithin, tocopherols, and tocotrinols. However, most of these phytoceuticals are removed from the rice bran oil as waste byproducts during the refining process. γ-oryzanol is one of such component having the potential to be used in nutraceutical, pharmaceutical and cosmoceutical preparations. It is a mixture of ferulic acid esters of sterol and triterpene alcohols. It occurs in rice bran oil at a level of 1-2 per cent where it serves as natural antioxidant. The article describes the production of rice bran oil from rice bran and different methods of extraction of γ-oryzanol from rice bran oil. It also reviews the health care properties of γ-oryzanol.

Keywords: Rice bran oil, Edible oil, γ-oryzanol

IPC Code: Int.Cl.7: C 08 B 30/04


Introduction

Rice bran obtained during milling of rice is gaining commercial importance in the world as it has many beneficial nutritive and biological effects. Rice bran oil (RBO) can be extracted from rice bran by solvent extraction using food grade n-hexane1 or in solvent free process by using ohmic heating2 or supercritical fluid extraction technology3. The crude rice bran oil obtained in the solvent extraction process is subjected to either chemical refining4 or physical refining5 to meet the specifications of edible grade vegetable oil.

Chemical refining of crude rice bran oil yields better product in terms of colour and cloud point5. However, this process also causes high refining losses in the form of wax sludge, gum sludge, and soap stock4. These residues, produced in the RBO refining industry, are the rich source of many nutraceutical like, oryzanols, tocopherols, vitamin E, ferulic acid, phytic acid, lecithin, inositol and wax6.

γ-oryzanol component of rice bran oil was first presumed to be a single component7. But later it was determined to be a fraction containing ferulate
(4-hydroxy-3-methoxy cinnamic acid) esters of triterpene alcohols and plant sterols8. Cycloartenyl ferulate, 24-methylenecycloartanyl ferulate and campesteryl ferulate (Scheme 1) are the three major components and account for 80 per cent γ-oryzanol9. The γ-oryzanol component of rice bran oil can be simultaneously separated and quantified by high-performance liquid chromatography8.

Oryzanol is an antioxidant compound and is associated with decreasing plasma cholesterol10, lowering serum cholesterol11, decreasing cholesterol absorption11 and decreasing platelet aggrigation12. Oryzanol has also been used to treat hyperlipidemia13, disorders of menopause14 and to increase the muscle mass15.

India is the second largest producer of paddy after China and contributes about 23 per cent of the total world production of paddy6. Japan contributes just 2 per cent of the total world production of paddy and produces dozens of high value chemicals and nutraceutical from the derivatives of paddy6, but unfortunately in India the potential of rice bran oil as cooking oil still remains largely untapped. Table 1 gives the potential and actual exploitation of rice bran in India6.

The article describes the extraction and refining method of RBO, and extraction of γ-oryzanol from RBO. It gives a detailed review of the health care properties of γ-oryzanol.

Table1— Rice bran potential and actual exploitation in India (1995-96 to 2001-02)

Year

1995-96

1996-97

1997-98

1998-99

1999-00

2000-01

2001-02

Paddy production

Million Mt

119.40

120.80

122.30

118.60

135.10

127.10

136.5

Rice production

Million Mt

79.6

81.7

82.5

86.1

89.7

84.90

91.00

Total rice bran potential, million Mt

(7.5 per cent of Rice)

6.00

6.13

6.19

6.46

6.73

6.37

6.83

Rice bran oil

Potential, lakh Mt,

(15 per cent recovery)

9.00

9.20

9.30

9.70

10.10

9.60

10.20

Actual rice bran

Processing, lakh Mt

32.00

32.00

33.00

32.00

33.10

33.00

36.00

Actual production of

Rice bran oil, Lakh Mt

 

 

 

 

 

 

 

Edible:

3.10

3.10

3.50

3.50

3.70

3.80

4.30

Non edible:

1.70

1.70

1.50

1.30

1.30

1.20

1.20

Total

4.80

4.80

5.00

4.80

5.00

5.00

5.50

Untapped potential

Rice bran oil, lakh Mt

4.20

4.30

4.30

4.20

4.20

4.80

4.70

Percentage of exploitation

53

52

53

50

54

50

54

 

 

Extraction and Refining of Rice Bran Oil

Hexane is used as a solvent to chemically extract oil from rice bran16. However, hexane poses potential fire, health, and environmental hazards17. Therefore, short chain alcohols, especially ethanol and isopropanol have been proposed as the alternative extraction solvent due to their greater safety and reduced probability of regulation16,18,19. Many studies have been conducted using isopropanol as a solvent for extraction of soybean and cotton seed oil20-26. However, only a few studies have been conducted on rice bran using isopropanol or ethanol as an extraction solvent. Isopropanol has been used to extract rice bran oil, rich in B-vitamins27 and ethanol has been used to extract rice bran oil rich in tocopherols and
B-vitamins28. Weicheng et al.29 have compared isopropanol and hexane as extraction solvents for recovery of vitamin E and oryzanol from stabilized rice bran and found that isopropanol is a promising alternative solvent to hexane for extraction of oil from stabilized rice bran. Shen et al.30,31 have studied the solubility of rice bran oil and some constituents, in dense and supercritical CO2. Kuk and Dowd32 studied the solubility of rice bran oil and its classes of compounds in SC-CO2. Various workers3,33,34 have studied the extractability and the scaling up of
SC-CO2. Kim et al.35 have studied the use of SC-CO2 to enrich the rice bran oil in essential fatty acids. The use of SC-CO2 to fractionate rice bran oil by supercritical fluid fractionation (SFF) for selective enrichment in sterols and lipid species of rice bran oil has also been studied36,37,38 Giuseppe et al.39 have evaluated the supercritical fulid extraction (SFE) technology for the recovery of all the rice by-products and novel conversion process to manufacture value added food products. In their study they have reported the highest extraction yield of 4.93g of rice bran oil with only 100 g of CO2 at 80
°C and 10,000 psi pressure. According to their study SC-CO2 can be used to extract oil efficiently and rapidly from all the byproducts of rice. But the high cost of the equipment to extract the oil is the only limiting factor for the proposed technology.

 

Crude RBO

 

 

 


Filtration

 

 

 

Hydration 2per cent, 750 C

 

 

 


Addition of CaCl2 solution

 

 

 


Winterisation

 

 

 


750 C to 200 c @ 0.40 C/min

 

 

 


Centrifugation at 200C

 

 

 


Vacuum dehydration and bleaching (acid activated bleaching earth)

 

 

 


Filtration

 

 

 


PHE to 20C

 

 

 


Winterisation 24 hours

 

 

 


Filtration

 

 

 


Deacidification & deodorisation

 

 

 


Polishing

 

Fig. 1¾Physical refining of rice bran oil

 

Rice Bran

 

 

 


Pelletization

 

 

 


Solvent treatment

 

 

 


Crude RBO + Defatted bran

 

 

 


Dewaxing

 

 

 


Dewaxed oil + Wax sludge

 

 

 


Degumming

 

 

 


Degummed oil + Gum sludge

 

 

 


Alkali treatment

 

 

 


Refined oil + Soap stock

 

 

 


Bleaching & deodourization

 

 

 


Chemically refined rice bran oil

 

Fig. 2—Chemical refining of rice bran oil

 

Food grade rice bran oil is obtained by subjecting the crude rice bran oil (CRBO) to either physical refining5 (Fig.1) or chemical refining4 (Fig.2). Gum sludge, wax sludge and soap stock sludge are the waste byproducts produced in the chemical refining process and are underutilized presently. Lloyd et al.40 have studied the effect of processing on the presence
of antioxidants in rice bran, while Yoon and Kim41 have studied the effect of refining on γ-oryzanol content in hexane extracted rice bran oil. The effect of different processing steps of refining on retention or the availability of
g-oryzanol has been investigated by Krishna et al.42 According to the study degumming and dewaxing of crude RBO removed only 1.1 and 5.9 per cent of oryzanol while the alkali treatment removed 93.0 to 94.6 per cent of oryzanol from original crude oil. The oryzanol content of oil extracted from the bran of 18 Indian paddy cultivars ranged from 1.1 to 1.74 per cent for physical refined RBO while for alkali-refined oil it was 0.19-0.2 per cent. The oil subjected to physical refining retained the original amount of oryzanol after refining whereas the chemical refined oil showed a considerable lower amount (0.19 per cent). Thus the Oryzanol which is lost during chemical refining process has been carried into the soap stock. The content of Oryzanol in the RBO, soap stock, acid oil and deodorizer distillate were in the range: 1.7-2.1per cent, 6.3-6.9 per cent, 3.3-7.4 per cent and 0.79, per cent respectively. These results show that the processing steps viz., degumming, (1.1 per cent), dewaxing (5.9 per cent), physical refining (0 per cent), bleaching and deodorization of the oil did not affect the content of oryzanol appreciably, while 83-95 per cent of it was lost during alkali refining.

Table 2— Comparison of γ-oryzanol yield by solvent extraction and SFE

 

Solvent extractiona

SFEb

SFEc

Yield (mg/g of rice bran)

1.68± 0.02

5.39±0.43

1.11±0.07

Concentration

 

 

 

(mg/g of extract)

11.8± 0.2

51.0± 5.5

674.6± 148.1

 

 

 

 

aExtraction with hexane/isopropanol (50:50) at 600C for 60 min

bExtraction under 680 atm at 500C for 25 min

cExtraction under 680 atm at 500C and collection between 15-20 min

 

 

Extraction and Purification of γ-Oryzanol

γ-oryzanol present in rice bran can be extracted by using organic solvents or by using supercritical CO2 technique. Xu and Godber43 have compared the supercritical fluid and solvent extraction method for extracting γ-oryzanol from rice bran. According to their study, a solvent mixture with 50 per cent hexane and 50 per cent isopropanol (vol\vol) at 600 0C for
45-60 min produced the highest yield (1.68 mg/g of rice bran) of γ-oryzanol among organic solvents tested. Saponification, during solvent extraction decreases the yield of γ-oryzanol. However the yield (5.39mg/g of rice bran) of γ-oryzanol in supercritical fluid extraction at 500C and 680 atm pressure for
25 min was approximately four times higher than the highest yield of solvent extraction. Also a high concentration of γ-oryzanol in extract was (50-80 per cent) obtained by collecting the extract after 15-20 min of extraction under optimized condition. Table 2 lists the yields of γ-oryzanol from rice bran and concentrations in extract, obtained by solvent extraction and SFE, respectively37.

γ-oryzanol can be extracted from the raw oils of rice bran and ferment, maize and barley by distillation of these oils at comparatively low temperature. The residue obtained is then extracted with hydrosol solvents and alkalinized below 0.5N and the extract is neutralized with organic acids to pH 6. In this process, raw γ-oryzanol can be crystallized having melting point 135.70 C and UV bands maximum at 216, 231, 291 and 315 mμ. Yamamoto and Takeshi44 stirred 1 kg of raw rice bran oil with a solution of 150 g 90 per cent NaOH in 150 ml water and stored it for one day at room temperature. Then it was acidified to pH 4 by H2SO4 and heated to 800C followed by addition of
50 g NaCl to give an oily layer which was washed with aqu. NaCl solution. Then some methanol was added to extract as much water as possible and then again 500 mL methanol was added. The mixture was cooled for 2 h at 00 C to precipitate the waxy components. The wax was then filtered and a solution of 5g H2SO4 in 300 mL methanol was added to the filtrate. After 24 h at 30-400C with periodical stirring methanol was evaporated and 2 per cent(of filtrate wt) acid clay added. The mixture was heated for 30 min. at 1000 C in vacuo, filtered and the filtrate was distilled at 2 mm pressure. To 100 g residue, 100g
n-hexane was added with stirring. The solvent was distilled and the same treatment repeated with 100 mL methanol. The residue was extracted 3- times with
50 mL 0.5N methanolic NaOH. Then the extracts were neutralized with methanolic acetic acid to pH 6.8-7 and stored to precipitate 3g raw crystallized
γ-oryzanol.

γ-oryzanol can also be extracted from alkali treated rice bran oil by hydrolyzing it with dil. HCl and by refluxing the residue with a solution of NaOH in methanol. The saponified solution is treated with methanol and filtered. The filtrate is neutralized and the methanol is evaporated. The residue is treated with dilute HCl, dissolved in diethyl ether and treated with disodium trioxide to remove the fatty acid. Then it is washed with water, dried and evaporated to give a residue containing oryzanol45.

Oryzanol can be precipitated from the alkaline oil foots of rice bran oil by treating it with methanol, acetone or isopropanol and fatty acids46. Dissolving RBO with methanol, acetone or isopropanol and treating with sodium dihydrogen phosphate, disodium citrate or disodium EDTA can also precipitate oryzanol47. γ-oryzanol can also be precipitated from alkaline oil cake of rice bran oil by treating the oil cake with methanol or ethanol followed by passing of CO2 with stirring. It is then filtered and the residue is washed with methanol and dried to give yellow powder containing oryzanol48.

Crude γ-oryzanol isolated from rice bran oil can be purified by treatment with the ketones and /or alcohols. Then it is filtered and cooled to give a crystal of purified oryzanol49. Shimizu50 has given a method for separation of the highly concentrated oryzanol by two-step alkali treatment.

Crude rice bran oil contains 1.5 to 2.9 per cent of oryzanol and during refining, about 90 per cent of the oryzanol goes into the soapstock as a refinery waste4 .The commercial products of rice bran oil industry had a varied oryzanol content of 1.8 to 2 per cent in crude oil, 0.19-0.22 per cent in chemically refined oil and 2.21-6.71 per cent in the soapstock4. Therefore, oryzanol needs to be recovered from the soap-stock of rice bran oil. Physically refined RBO has retained about 85-90 per cent of oryzanol in the oil itself as no soapstock is produced during removal of fatty acids. Processing of soap stock to recover oryzanol has been made difficult due to use of varied conditions of refining of RBO. Oryzanol has been isolated from the commercial soapstock of rice bran oil by using solvent extraction methods, as shown in Fig. 3. Kim and Kim38 have also given a method for the separation of oryzanol from the refining byproducts of rice bran oil.

The cost of oryzanol varies depending on the grade and the manufacturing method in the international market4 (Rs 1000/kg - Rs 7000/kg prepared using chemical treatment process and Rs 15, 000/kg-75, 000/kg for solvent free processed products). With the production of 200 mkg of chemical refined oil, India has the potential of recovering 4 mkg of oryzanol.

Soap stock

 

 

 

Solution in solvent mixture (recovered and reused)

 

 

 


Extraction of oryzanol

 

 

 


Oryzanol concentrate (20-30per cent) purity

 

 

 


Fatty acid + Potassium chloride (by products)

 

Fig. 3¾Preparation of oryzanol concentrate from rice bran oil soap stock

 

Health Care Properties of Gamma Oryzanol

 

Antioxidant Property

At the molecular and cellular levels, antioxidants serve to deactivate certain particles called free radicals. Free radicals are the natural by-products of many oxidative metabolic processes within cells. These free radicals can cause damage to cell walls, certain cell structures and genetic material within the cells. Vitamin E is thought to be the most effective antioxidant due to its abundance in the body.
γ-oryzanol found in rice bran oil is also a potent antioxidant. One test-tube study found that γ-oryzanol was more than four times as effective at stopping tissue oxidation as vitamin E52. The nutritional function of γ-oryzanol components may be related
to their antioxidant property because of the ferulic acid structure. Ferulic acid is a phenolic acid antioxidant53-56, and Ohat et al.57 have identified ferulic acid sugar esters as active components in corn bran hemicelluloses fragments. However the antioxidant capacities of γ-oryzanol components were not known previously and were studied by Zhimin et al.58 by using a linolenic acid model. According to the study the three major components of γ-oryzanol (24-methylene cycloartanyl ferulate, cycloartenyl ferulate and campesteryl ferulate) evidenced significant antioxidant activity when they were mixed with linoleic acid in a molar ratio of 1:100 and 1:250 but not in a molar ratio of 1:500. Antioxidant activity of tocopherols, tocotrinol, and γ-oryzanol components from rice bran against cholesterol oxidation were studied by Xu et al.59 and highest antioxidant activity was found for the 24-methylenecycloartanyl ferulate. All the three γ-oryzanol components had activities higher than that of any of the four vitamin E components (α-tocopherol, α-tocotrinol, γ–tocopherol, and γ-tocotrinol)59. Inhibition of cholesterol autoxi­dation by the nonsaponifiable fraction in rice bran was studied Kim et al.60 in an aqueous model system.

 

Effects on Cholesterol

One of the most important properties of γ-oryzanol is its cholesterol lowering property. There are several studies on humans and animals61-65 showing that the rice bran oil (RBO) has the property of lowering low density lipoprotein cholesterol and total serum cholesterol and increasing the high density lipoprotein cholesterol to some extent either by influencing absorption of dietary cholesterol or by enhancing the conversion of cholesterol to fecal bile acids and sterols. Further studies confirm that the g-oryzanol component of RBO is responsible for the hypocholesterolemia66-68.

Recently, an experiment was conducted on human being to see the hypocholesterolemic property of RBO. In the experiment 66 persons were fed cooked rice, sprayed with brown rice extract for 30 d. The extract contained mainly inositol, γ-amino butyric acid (GABA) and, γ-oryzanol. Levels of lipid serum (total cholesterol, beta lipoprotein and LDL cholesterol) decreased significantly. Total cholesterol showed a remarkable decrease, especially in persons with total cholesterol level of more than 200mg/dL before study69.

The mechanism of cholesterol lowering action of, γ-oryzanol was investigated by Rong et al.70. Hamsters were made cholesterolemic by feeding chow-based diets (containing coconut oil and 0.1 per cent cholesterol with or without oryzanol) for 7 weeks. Relative to control animals’ oryzanol administration resulted in significant reduction of plasma total cholesterol levels (28 per cent), non-high-density lipoprotein cholesterol (non-HDL-C) 34 per cent, and 25 per cent reduction in percentage cholesterol adsorption. Aortic fatty streak formation was reduced by 67 per cent in the oryzanol treated animals. It was concluded that oryzanol was at least partly responsible for the cholesterol lowering action of RBO and is associated with the reduction in aortic fatty streak formation. Seetharamiah and Chandrasekhara71 have found that the serum total, free esterified and (LDL+VLDL) cholesterol level of rats maintained at a 10 per cent RBO diet were lower than those maintained on a 10 per cent ground nut oil diet. Addition of 5 per cent oryzanol to the diet containing rice bran further reduced the serum cholesterol. The authors have concluded that the cholesterol lowering property of RBO might be due to oryzanol and /or other nonsaponifiable constituents present in RBO. Seetharamiah and Chandrasekhara72 also found that hypertriglyceridemia induced by fructose was lower in animals maintained on a 0.5per cent oryzanol containing diet than the corresponding control. Sugano
et al.73 have observed that blending of rice bran oil with safflower oil in definite proportion (7:3 w/w) magnified the hypocholesterolemic activity compared with the effect of each oil alone. They have also reported similar results in their later studies60.
γ-oryzanol can also lower the plasma cholesterol level74. Although the mechanism underlying this
effect is not apparent at present the presence of oryzanol and tocopherols in the rice bran is thought to be responsible for this favorable effect. The blending may have a practical significance. Hiramatsu et al.75 have studied the effect of γ-oryzanol on atheroma formation in hypercholestrolemic rabbits. Cicero and Gaddi76 have studied the effect of rice bran oil and
γ-oryzanol in the treatment of hyperlipoproteinamia. When added to a high cholesterol diet it also inhibits platelet aggregation, preventing heart attacks and strokes7. Nutritional and biochemical aspects of the hypolipidemic action of rice bran oil have been reviewed by Rukmini and Raghuram77. Scavariello and Arellano78 have reviewed the physiological, antioxidant and hypocholestrolemic properties of
g-oryzanol.

 

Effects on Serum TSH

A single oral dose (300 mg) of γ-oryzanol extracted from rice-bran oil produced a significant reduction on the elevated serum TSH level in hypothyroid patients. Similarly, chronic treatment with γ-oryzanol resulted in decreased serum TSH level in 6 of 8 patients. There was no change in the serum level of thyroxine-iodine and triiodothyronine during the study. In addition, there was no difference in the serum, thyroid stimulating hormone (TSH) response to thyroid releasing hormone (TRH) in hypothyroid patients and normal subjects. These observations suggest that γ-oryzanol inhabits serum TSH levels in patients with primary hypothyroidism, possibly by a direct action at the hypothalamus rather than the pituitary79.

 

Effects on Menopause

Two uncontrolled studies have investigated the use of γ-oryzanol for menopause. A Japanese study in the 1960s gave 13 women who had hysterectomies, also called surgical menopause, 100 mg γ-oryzanol three-times daily for 38 d and found that it halved menopausal symptoms such as, hot flashes in more than 67 per cent of the women14. In a later Japanese study, 40 perimenopausal women received 300 mg γ-oryzanol daily for four to eight weeks. Ninety per cent of the women improved and 40 per cent experienced “excellent effectiveness” in reducing menopausal symptoms. Yamauchi et al.80 have reported the inhibition of LH secretion in rat by γ-oryzanol. Ishihara et al.81 have studied the clinical effect of γ-oryzanol on climacteric disturbance on serum lipid peroxidase.

 

Effects on Muscle

γ-oryzanol /ferulic acid, inposine, chromium and medium chain triacyl glycerol are used as ergogenic aids by strength/power athlets82. The effect of
γ-oryzanol Supplementation during resistance exercise training has been explained by Fry et al.83. Very preliminary evidence suggests that γ-oryzanol may increase endorphin release and aid muscle development15, 84. These findings have created an interest in using γ-oryzanol as a sports supplement.

 

Carcinogenic Effects

The carcinogenic potential of γ-oryzanol, a drug mainly used for the treatment of hyperlipaemia was studied in F344 rats85 and B6C3F1 mice86. The findings indicate that under the experimental conditions described, γ-oryzanol was not carcinogenic in F344 rats and B6C3F1mice. Inhibitory effect of cycloartenol ferulate, a component of rice, on tumor promotion in two-stage carcinogenesis in mouse skin was studied by Yasukawa et al.87. According to their study the active components of rice bran, sitosterol ferulate,
24-methylcholesterol ferulate, cycloartenol ferulate and 24-methylenecycloartanol ferulate inhibited markedly the TPA-induced inflammation in mice. Cycloartenol ferulate, a component of γ-oryzanol in rice bran oil shows marked inhibition on the tumour promoting effect of TPA in 7, 12-dimethylbenz [a] anthracene-initiated mice. Hirose et al.88 have studied the modifying effects of phytic acid and γ-oryzanol on the promotion stage of rat carcinogenesis75. Sugano
et al.89 have studied the health benefit of rice-bran oil and its anticancer property.

 

Uses of γ-oryzanol

γ-oryzanol has a protective role in UV-light induced lipid peroxidation and hence it is used as a sunscreen agent. A cosmetic sunscreen composition containing ferulic acid and γ-oryzanol has been patented90. Ferulic acid and its esters stimulate hair growth and prevent skin aging91. Such preparations are claimed to accelerate cell differentiation and to reduce wrinkles in aged women. The eyebrows, eyelashes, and surrounding skin are protected from oxidative damage, due to environmental influence or chemical treatment by use of compounds containing ¡-oryzanol92.

¡-oryzanol is insoluble in water and various ways of solubilizing the compound for cosmetic, pharmaceutical, and food applications have been described. Oryzanol becomes water-soluble when treated with urea, nicotinamide and/or thioctamide dissolved in acetone or etanol-acetone mixture93. Another method involves conversion to a cyclodextrin inclusion compound94. Solubilization of γ-oryzanol into medicinal drinks is achieved by using sucrose fatty acid ester and ethoxylated HCO (ref. 95 and 96). The drinks are useful as revitalizing tonics. Solubilization of
γ-oryzanol in water has also been studied by
Hiroshi97. Ricebran oil containing inositol and/or
γ-oryzanol is claimed to be useful for improving the quality of cooked rice98. Apart from all the health benefits, it is light and delicate in salads and unlike olive or canola, has very low flavour which makes it excellent for both frying and baking without changing the taste of the recipe. Rice bran oil has a very high heat tolerance or smoke point (around 475
°F or higher) and one can fry, sauté and stir fry without thickening, smoking, foaming or breakdown.

 

Conclusions

India has become the second largest producer of rice bran oil which uniquely contains γ-oryzanol. This high value compound can be isolated from physical refined oil and from the residual soap stock produced during chemical refining of the oil. Therefore, processors of rice bran oil should exploit this situation for their economic advantage to produce high value products for pharmaceutical and nutraceutical use. The new separation process like supercritical and fluid extraction can be utilized for γ-oryzanol extraction. Also, more R&D work should be undertaken for development of a low cost refining process (for RBO) retaining maximum percentage of γ-oryzanol in the refined oil.

 

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