Title of Invention

A PROCESS FOR THE PRODUCTION OF MICRONUTRIENTS RICH RICE BRAN OIL USING SUPERCRITICAL CARBON DIOXIDE EXTRACTION

Abstract

This invention relates to a novel process for the production of micronutrient rich rice bran oil with good oxidative stability by supercritical CO2 extraction. The Supercritical fluid extraction process could be viable commercially for the production of micronutrients(phytosterols, oryzanol, and tocols) rich edible rice bran oil as a premium quality health product for a "niche market" by combining extraction and refining as compared to that obtained from separate hexane-extraction and refining in the conventional processing. This may compensate for the higher capital investment cost of the supercritical extraction process. Solvent free rice bran oil can be obtained because the extracts are separated completely from the solvent (CO2) by decreasing the pressure. Low thermal energy requirement favors supercritical extraction since energy intensive solvent recovery by distillation/evaporation in conventional method is eliminated. Supercritical CO2 extracted rice bran oil has good oxidative stability and excellent color quality compared to hexane extracted rice bran oil.

Full Text

A PROCESS FOR THE PRODUCTION OF MICRONUTRIENTS RICH RICE BRAN OIL USING SUPERCRITICAL CARBON DIOXIDE EXTRACTION . This invention relates to a novel approach to combined extraction and refining of rice bran oil rich in health promoting micronutrients using supercritical fluid extraction technique. BACKGROUND OF THE INVENTION: Rice bran, a potential commercial source of edible oil in rice producing countries, is a by-product of rice milling industry. India is the second largest producer of rice and rice bran in the world after China. India has the potential of 1.5 million metric tones (MMT) rice bran oil against current production of 0.5 MMT, most of which is used as industrial oil. Rice bran oil is considered to be most nutritious edible oil as it is rich in polyunsaturated fatty acids with extremely high levels of oryzanol (1-2%), tocols (1000-2000 ppm), sterols (1-3%) etc, that are known to modulate cardio vascular disease, aging and promote general well being. Rice bran oil could be an alternative to olive oil and therefore is known as "Indian olive oil". Conventional processing involves two separate processing namely solvent extraction and refining, comprising several steps and array of equipments. Currently, hexane extraction is employed for extraction of rice bran oil in industry. The following process steps are involved in solvent extraction. Pelletized rice bran is extracted with solvent, the micella with solvent thus obtained is then desolventised by distillation and finally sparged with superheated steam to remove residual solvent (Fig.l). The resultant crude rice bran oil is then subjected to physical refining as follows. The crude rice bran oil is first degummed and dewaxed to remove phosphatides and wax through winterization and centrifugation steps. The degummed oil is then bleached, winterized, filtered, deacidified and deodorized to get refined rice bran oil (Fig.2). Rice bran oil is the most difficult oil to refine meeting with quality specification for edible oil. Harsh process conditions employed for solvent extraction and removal of color and other extraneous matter results in rice bran oil poor in micronutrients. Besides, rice bran oil by solvent extraction contains significant quantities of constituents such as wax, phosphatides, pigments etc, which are associated with processing problems, leading to poor quality end product on refining. Wax occludes oil, resulting in high losses of oil during the dewaxing and refining steps and phosphatides more than 5 ppm (equivalent 'p') imparts brown color at 2500C employed for deacidification. Rice bran oil processing problems are further compounded by milling of rice and storage of rice bran and solvent extraction conditions as practiced now. In the present situation, non-utilization of bran and bran oil to their full potential for edible use could be traced to these problems. Chemical refining using caustic soda is an alternative method adopted for refining rice bran oil to obtain lighter colored refined oil. However this process involves heavy neutral oil loss and almost complete removal of oryzanol and significant loss of health promoting micronutrients such as tocopherol/tocotrienols, phytosterols, etc. Chemical refining of rice bran oil therefore is not only uneconomical but it also results in a product poor in micronutrients mentioned before. Supercritical fluid extraction (SFE) is an emerging technology for edible oil processing with a high potential to replace the conventional solvent extraction. There is a significant advantage for this technology over conventional process. Based on our experimental results we are proposing a novel approach viz: combined extraction and refining of rice bran oil that retains most of its health promoting micronutrients in the final product. Schematic presentation of combined extraction and refining of rice bran oil using supercritical CO2 is given in Fig. 3. One of the main advantages of supercritical fluid extraction over conventional extraction is that the final separation of the solvent can be easily achieved. Additional steps such as evaporation or distillation to separate the solvent fi-om the extract, degumming and dewaxing to remove the phosphatides and wax in the conventional process can be eliminated in supercritical fluid extraction. Conventional process involves high energy cost and time consumption process steps and finally producing a poor quality product. Use of organic solvents is being restricted due to environmental and health concern and with increasing consumer awareness organic solvents may be banned in future if a commercially viable alternative is available. In this context CO2 as a solvent in food processing and particularly for edible oil processing assumes importance. CO2 is non toxic, non-inflammable, causes no environmental problems, cheap, and easily accessible. However, CO2 attains solvent power at its supercritical state (Tc= 310C, Pc= 73.8bar) and at higher pressure and temperature and can be separated from any solute more easily and more completely because of its extreme volatility. High capital cost is the only disadvantage adversely affecting the use of SFE on commercial scale operation in edible oil extraction today. The present innovation is towards a cost effective process considering capital cost and environmental and health cost. A few studies of supercritical fluid extractions of rice bran oil have been reported. In 1991 Ramsay and Cols compared the extraction of rice bran oil and the sterol composition of the extracted oil using conventional hexane and supercritical CO2 with and without co-solvents (Ramsay, M.E., Hsu, J.T., Novak, R.A. and Reightler, W.J., Food Technology, 1991). According to this study, total sterol content was lower (88.7%) compared to that of hexane extracted oil. Kim and Cols correlated the extraction rate of rice bran oil. They identified the presence of squalene in the supercritical CO2 extract but were unable to extract it using the conventional process (Kim, H.J., Lee, S.B., park, K.A., Hong, I.K., Separation and Purification Technology, 15, 1999). Dvmford and King evaluated isothermal and thermal gradient supercritical fluid fi-actionation of rice bran oil as an alternative process of deacidification to minimize the phytosterol loss during the process (Dunford, N.T, and King, J.W., Journal of Food Science, 65(8), 2000). Kuk and Dowd extracted rice bran lipids with supercritical CO2, wherein only 5gms of rice bran was used for extraction. They could not reduce the phosphorous content of rice bran oil below 250ppm in this study. (Kuk, M.S., and Dowd, M.K., J. Am. Oil Chem. Soc. 75(5), 1998). The main objective of the present invention is to provide a novel ecofriendly process and health friendly product by the combined extraction and refining of nutritionally superior rice bran oil using Supercritical Carbon dioxide (SC-CO2) extraction. Another objective of the present invention is to provide a method for the production of rice bran oil with maximum yield comparable with that of solvent extraction and with no solvent residues. Another objective of the present invention is to provide a method for the production of rice bran oil with negligible wax and completely free from phosphatides that would yield clear and lighter colored oil and would simplify or avoid pre-treatment of dewaxing and degumming steps, leading to elimination of oil loss at these steps in the conventional processing. Another objective of the present invention is to provide a method for the production of rice bran oil with negligible iron and copper contents that would impart improved stability to the end product. Another objective of the present invention is to provide a method for the production of rice bran oil with highest retention of micronutrients such as tocopherols, tocotrienols, oryzanol and phytosterols and therefore to position it as a health product or functional food. Another objective of the present invention is to provide a method for the production of rice bran oil with excellent color quality that avoids bleaching in this process. Another objective of the present invention is to provide a method for the production of rice bran oil with good oxidative stability compared to that obtained by conventional refining. Accordingly, the present invention provides another objective of the present invention is also to provide a method for the production of rice bran oil conforming to legal specificational requirements for edible rice bran oil. a process for the production of micronutrients rich rice bran oil using supercritical carbon dioxide extraction and the said process comprising: packing of parboiled or rice bran with glass beads in a container cage inside the extraction vessel in a ratio ranging 1:0 to 1:2 (w/w); pressurizing the vessel to the required pressure ranging 200-600 bar at a temperature ranging 30-80°C and soaking raw rice bran for a period ranging 10-SOmints; subjecting to dynamic extraction over a period ranging 0.5-4 hrs with CO2 flow rate ranging 20-50g/min; passing the oil laden gas from the extractor through a heated metering valve anddepressurizing the extracted rice bran as obtained in step c) at a specified rate and storing CO2 in the recycle tank and collecting the extracted oil from the receiver. In an embodiment of the present invention micronufrient rice bran oil is characterized by presence free fatty acids(FFA) about 12.8%, tocols of about 1619 ppm, oryzanol of about 1.2%, phytosterols of about 2.0% , phosphatides (p) about 0.6ppm, wax about 0.8%, Fe about 1 ppm, and having a color value of about 102R. In another embodiment of the present invention micronutrient rice bran oil comprises of very low phosphatides , wax content and trace metals as compared to hexane extracted and chemically refined rice bran oils. In yet another embodiment of the present invention a pressure of 200-600bar is applied to get higher yield of micronutrients rich rice bran oil. In still another embodiment of the present invention extraction time ranging 0.5-4 hrs results in the maximum yield of rice bran oil. In still another embodiment of the present invention supercritical extraction with CO2 yields rice bran oil with excellent color quality. In still another embodiment of the present invention supercritical extraction with CO2 yields rice bran oil which skips pretreatment of dewaxing and degumming . In still another embodiment of the present invention supercritical extraction with CO2 yields rice bran oil with negligible iron and copper which improves the stability of the product DETAILED DESCRIPTION OF THE INVENTION: The following procedure has been developed for the extraction and refining of rice bran oil using supercritical carbon dioxide extraction. A schematic diagram of the pilot plant extraction unit is shown in Fig.4. Liquid CO2 is cooled to 5°C and the extraction vessel is heated to the required temperature by means of hot water circulated through the jacket of the vessel. Rice bran is sieved through a 0.5mm opening sieve and packed with glass beads (4.5 mm), in a container cage and is loaded into the extractor vessel (2L). The vessel is closed, and pressurized to the required pressure by means of a high pressure pump, and soaked the material at this pressure for a specified time. The vessel pressure is controlled by a backpressure regulator. Then the extraction is carried out over a specified time at a specified CO2 flow rate. The oil laden CO2 from the extractor passed through a gas-liquid separator where it was depressurized at a specified rate and CO2 is collected in the recycle tank, leaving the extracted oil in the separator. Time, Pressure, Temperature, mass flow rate, and particle size have been shown to affect the oil solubility during supercritical CO2 extraction. Oil recovery increased with extraction time in isobaric and isothermic conditions without modifier (Fig.5). Oil recovery increased with an increase in temperature of SC-CO2 under isobaric conditions. The temperature effect may be strongly related to the increase in the diffusivity of SC-CO2. As the pressure increased, the oil recovery also increased at isothermic conditions. It indicates that the density increase of SC-CO2 caused the increase in the rice bran oil extraction yield. Most significant finding is that phosphorous is not detected at a concentration equal to or above 0.6ppm in supercritical extracted rice bran oil, whereas hexane extracted rice bran oil contains about 480ppm for a particular sample. In the present process the extraction of FFA, tocols and sterols increased with increasing temperature at isobaric conditions and decreased with increasing extraction time at isothermic and isobaric conditions, since FFAs, tocols and sterols are extracted in the initial stage of the extraction and gets diluted in the oil as the oil yield increases (Fig.6,7,&8). Micronutrients such as tocopherols, tocotrienols and sterols are higher in supercritical CO2 extracted rice bran oil than those of hexane-extracted oil. In contrast with the extraction profile of tocols, FFAs and sterols; oryzanol is more difficult to extract from rice bran perhaps because of its rigid and voluminous polycyclic structure or package with other components of the rice bran matrix. It is observed that as the temperature, pressure and extraction time increases the oryzanol content also increases (Fig.9). Oxidative stability studies shows that supercritical extracted rice bran oil is more stable to oxidation than hexane extracted oil. SC-CO2 extracted rice bran oil has excellent color quality compared to hexane-extracted rice bran oil and SC-CO2 extracted rice bran oil does not require degumming/dewaxing and bleaching as far as oil color, wax and phosphorous content are concerned whereas the commercial solvent extraction process currently employed requires all the above refining steps. The physico-chemical characteristics of supercritical CO2 extracted rice bran oil and hexane-extracted oil are given in Table. 1. The following examples are given by way of illustration and therefore should not be constructed to limit the scope of the present invention. Examplel ISOgms of rice bran (SOOmicron) without packing material is taken in a cage and placed in the extraction vessel and is closed. The extraction vessel is heated to 70°C. The vessel is pressurized to 350 bar and soaked for ISmints at 350bar. After soaking period extraction is carried out for 3.5hrs with a CO2 flow rate of 40g/min. The oil laden gas from the extractor is passed through a heated metering valve where the supercritical CO2 is depressurized and the extracted oil is collected in a receiver and 16gms of rice bran oil is obtained. Example 2 ISOgms of rice bran (SOO micron) is mixed with ISOgms of glass beads (4.5mm) and taken in a cage and placed in the extraction vessel and is closed. Liquid CO2 is cooled to 5°C and the extraction vessel is heated to 70°C. The vessel is pressurized to 3S0bar and soaked for ISmints at 350bar. Then extraction is carried out for 3.Shrs with CO2 recirculation with a CO2 flow rate of 40g/min. The oil laden gas from the extractor is passed through a heated metering valve where the supercritical CO2 is depressurized, and the extracted oil is collected in a receiver and 30gm oil is collected. Example 3 ISOgms of rice bran (SOOmicron) is mixed with ISOgms of glass beads (4.Smm) and taken in a cage and placed in the extraction vessel, and is closed. Liquid CO2 is cooled to S°C and the extraction vessel is heated to 70°C. The vessel is pressurized to 300bar and the material is soaked for ISmints at 300bar. Then extraction is carried out for 3.Shrs with a CO2 flow rate of 40g/min. The oil laden gas from the extractor is passed through a heated metering valve where the supercritical CO2 is depressurized and the extracted oil is collected in a receiver and 24gms of rice bran oil is obtained. Example 4 ISOgms of rice bran (500micron) is mixed with 150 gms of glass beads (4.5mm) and taken in a cage and placed in the extraction vessel, and is closed. Liquid CO2 is cooled to 500C and the extraction vessel is heated to 70°C. The vessel is pressurized to SOObar and the material is soaked for ISmints at SOObar. Then extraction is carried out for l.Shrs with a CO2 flow rate of 40g/min. The oil laden gas from the extractor is passed through a heated metering valve where the supercritical CO2 is depressurized and the extracted oil is collected in a receiver and 30gms of rice bran oil is obtained. Example 5 ISOgms of rice bran (SOOmicron) is mixed with ISOgms of glass beads (4.Smm) and taken in a cage and placed in the extraction vessel, and is closed. Liquid CO2 is cooled to S°C and the extraction vessel is heated to 50°C. The vessel is pressurized to 350 bar and the material is soaked for ISmints at 350bar. Then extraction is carried out for 3.Shrs with a CO2 flow rate of 40g/min. The oil laden gas from the extractor is passed through a heated metering valve where the supercritical CO2 is depressurized and the extracted oil is collected in a receiver and 17.8gms of rice bran oil is obtained. Table 1. Physico Chemical Characteristics of SFE RBO, Hexane Extracted crude RBO and refined RBO. (Table Removed) The main advantages of the present invention; 1) The SFE process could be viable commercially for the production of micronutrients rich edible rice bran oil as a premium quality health product for a "niche market" by combining extraction and refining as compared to that obtained from separate hexane-extraction and refining in the conventional processing. This may compensate for the higher capital investment cost of the supercritical extraction process. 2) Solvent free rice bran oil can be obtained because the extracts are separated completely from the solvent (CO2) by decreasing the pressure. Low thermal energy requirement favors supercritical extraction since energy intensive solvent recovery by distillation/evaporation in conventional method is eliminated. 3) Consumption of CO2 and energy are reduced by recycling CO2 at high pressure. 4) Supercritical CO2 extraction has the advantage of selective extraction of micronutrients such as tocols, phytosterols and oryzanol. 5) Rice bran oil with negligible phosphatides and trace metals eliminates dewaxing and degumming steps practiced in the conventional refining. 6) No high temperature is used, which makes handling heat-sensitive substances easy and safe. 7) Supercritical extraction produces zero waste and no emission of solvent vapors that affect environment and health and therefore could be termed "Green technology". 8) Considering environmental and health cost related to solvent extraction process coupled with petroleum based higher energy cost, supercritical CO2 extraction could be viable in the near future. High capital cost of SFE could be reduced further by combining extraction and refining with minimal process steps in contrast to the conventional separate solvent extraction and refining involving large number of unit operations.. 9) Supercritical CO2 extracted rice bran oil has good oxidative stability and excellent color quality compared to hexane extracted rice bran oil. 10) "Natural" rice bran oil produced by this "Green technology" will have a premium price and "niche market". We Claim: 1) A novel process for the production of micronutrients rich rice bran oil with good oxidative stability by supercritical CO2 extraction which comprises; packing parboiled or raw rice bran with glass beads in a container cage inside the extraction vessel, characterized in pressurizing the vessel to the required pressure of 200-600 bar, at a temperature of 30-80°C, soaking the material for a period of 10-30mints, subjecting to dynamic extraction over a period of 0.5-4 hrs, at a specified CO2 flow rate of 20-50g/min, depressurizing at a specified rate and storing CO2 in the recycle tank and collecting the micronutrients rich extracted rice bran oil from the receiver. 2) A process as claimed in claim 1, wherein the rice bran oil contains micronutrients phytosterols,oryzanol, and tocols. 3) A process as claimed in claim 1, wherein rice bran oil with negligible phosphatides and trace metals and low wax content is obtained. 4) A process as claimed in claim 1, wherein a pressure of 300-500 bar is applied to get higher yield of micronutrients rich rice bran oil. 5) A process as claimed in claim 1, wherein extraction time of 1.5-3.5 hrs resulted in the maximum yield of rice bran oil. 6) A novel process for the production of micronutrient rich rice bran oil with good oxidative stability by supercritical CO2 extraction substantially as herein described with reference to the examples.

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1890-del-2004-abstract (23-02-2011).pdf

1890-del-2004-abstract.pdf

1890-del-2004-claims (23-02-2011).pdf

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1890-del-2004-correspondence-others (23-02-2011).pdf

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1890-del-2004-description (complete).pdf

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1890-del-2004-form-1.pdf

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1890-del-2004-form-3 (23-02-2011).pdf

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