Title of Invention

"A PROCESS FOR DEGUMMING AND PARTIAL DECOLORIZATION OF CRUDE GLYCERIDE OILS"

Abstract

The present invention relates to a process for degumming and partial decolorization of crude glyceride oils. The present invention particularly relates to a process for removal of phospholipids and partial removal of color compounds present in crude glyceride oils using hydrophobic nonporous polymeric membranes at enhanced permeate flux (solvent free basis) with suitable dilution in organic solvent. The invention aims to provide a process for the separation of impurities (phospholipids and color compounds) from crude glyceride oils to recover triglycerides without the application of severe chemical treatments, thus offering advantages over the conventional methods practiced by the industries. Edible oil/fat is being one of the most important primary food commodities, the technology for its production is of paramount importance.

Full Text

The present invention relates to a process for degumming and partial decolorization of crude glyccride oils. The present invention particularly relates to a process for removal of phospholipids and partial removal of color compounds present in crude glycende oils using hydrophobic nonporous polymeric membranes at enhanced permeate flux (solvent free basis) with suitable dilution in organic solventj The invention aims to provide a process for the separation of impurities (phospholipids and color compounds) from crude glyceride oils to recover triglycerides without the application of severe chemical treatments, thus offering advantages over the conventional methods practiced by the industries. Edible oil/fat is being one of the most important primary food commodities, the technology for its production is of paramount importance. Oilseeds are the major source for the production of edible oils. Pressing followed by solvent extraction is the most widely followed method to handle a variety of oilseeds. The oil obtained from the screw press amounts to 75% of the total oil content in the oilseed and is far superior in quality than the oil obtained by solvent extraction. The major vegetable oil producers in the world mix the expelled oil and solvent extracted oil before refining. Low oil bearing materials such as rice bran and soybean are directly extracted with solvent either after pelletization or flaking. The extracted oil is subjected to refining to improve its quality. The refining treatment should remove or reduce, as much as possible, impurities that would adversely affect the quality of the end product and the processing efficiency. The principal impurities are water, dust, free fatty acids (FFA), partial glycerides, phosphatides, oxidation products, pigments and compounds containing trace elements such as copper, iron, sulfur and halogens. These impurities are removed at various steps in the conventional chemical refining, namely, degummmg, neutralization, washing, drying, bleaching, filtration and deodorization. In conventional physical refining, FFA are distilled off and this process offers many advantages over the chemical method such as improved product yield, elimination of soapstock splitting and reduced effluent quantity. However, the quality requirements of the pretreatment is much more stringent, the most important being very low phosphorus levels in the treated oil. Degumming is the first step during the refining of crude vegetable oils, wherein phospholipids are removed, which otherwise would act as emulsifying agents leading to loss of neutral oil and finally resulting in low grade finished product. The phospholipids are classified as hydratable and nonhydratable phospholipids (NHP). The principle component of the hydratable phospholipids is phosphatidylcholine. whereas the NHP mainly consist of the calcium and magnesium salts of phosphatidic acid (PA) and of phosphatidylethanolamine. Several processes have been developed to bring down the phosphatide content of oils, in other words, to increase the efficiency of the degumming process. In the conventional processing, water or dilute acid is used during the degumming step. In the water-degumming process, phospholipids are precipitated by hydration followed by agitation and removed by centrifugation. The phospholipid content of average quality of oil is reduced to a range between 1800 and 6000 mg/kg, and the corresponding range of phosphorus content is 60-200 mg/kg. Acid degumming, where the hydratability of salts of PA is increased by addition of either phosphoric or citric acids, brings down the phospholipid content to about 1500 mg/kg. However, acid Treatment may have an influence on the composition of the resulting phospholipids affecting its quality as well as application. Super-degumming process, a patented process widely being used in the industries, produces an oil with a maximum phospholipid content of 900 mg/kg [Fette Seifen Anstrichm., 84:543-546 (1982)]. The amount of acid used in the acid-degumming process varies between 0.05 and 0.2% of the oil weight and is even as high as 0.5% in oils containing an initial phospholipid content of 6000 mg/kg and higher. The removal of color in edible oil is necessary to provide an acceptable finished product to the consumer. The conventional bleaching operation employing a clay product is basically an adsorption process that removes not only color compounds (carotenoids, chlorophyll and others) but also other minor impurities. The residual soaps are removed and peroxides are decomposed into aldehydes and ketones due to further oxidation. These decomposition products are also adsorbed to the bleaching agent. Thereby stability and flavor of the oil are also improved. Bleaching is usually achieved by heating the oil to about 100°C and passing through a bed of activated bleaching clay or carbon. The small amounts of bleaching earth carried along by oil are removed by filtration. The bleaching earth is used at 2% level and is a major cost apart from the associated disposal problem. 'There are several other disadvantages with the current industrial bleaching practice related primarily to the retention of oil, which is in the range of 30-70% of the weight of the activated earth used in the process. Membrane process has been evaluated as an alternate process for the conventional refining process. Reference may be made to the research work carried out by various researchers using micelle-enhanced ultrafiltration (MEUF) for the dugumming of hexaneoil miscella [US patents 4,062,882 (1977); 4,093,540 (1978); 4,533,501 (1985); 4,545.940 (1985); 4,787,981 (1988); WO patent 0,189,674 (2001) and research publication ,/. Membrane Sci., 134:101-108 (1997)]. In some of the above patented processes some additives were also introduced before ultrafiltration for reduction of other impurities present in the crude oil. The rejection of color compounds during the ultrafiltration process varied with the type of crude oil [J. Am. Oil Chem. Soc., 78, 803- 807 (2001)]. In ultrafiltration process the rejection is mainly due to size exclusion. Since the color compounds are much smaller as compared to the pore size (10,000 - 20,000 Da) of the ultrafiltration membrane, the rejection of color compounds are mainly due to their affinity for the phospholipid reverse micelles formed in the system. The rejection performance reported actually depended on the composition of color compounds and their relative polarity. US patents 5,310,487 (1994) and 5,545,329 (1996) deals with the invention of a membrane module system that provides optimal separation performance and service life. US patent 6,207,209 (2001) describes a method of conditioning a polymeric micro filtration membrane for removing phospholipids from vegetable oil misceila. US patent 4.062,882 (1977) describes a membrane filtration process for retaining phosphatide micelles from crude glyceride oil solutions in organic solvents and preferably suggests the use of membranes made from synthetic resin (ultrafiltration membranes) for the purpose. The studies using nonporous denser polymeric composite membranes with undiluted crude vegetable oils and model oil systems revealed that the nonporous denser membranes were effective in reducing phospholipids, color compounds and oxidation products while retaining beneficial compounds (Subramanian, PhD Thesis, University of Tsukuba. 2001 j. Model studies increased the understanding on the mechanism of rejection of phospholipids, color compounds and oxidation products as well as differential permeation of triglycerides, tocopherols and FFA. However permeate flux needed improvement for the industrial adoption of this technology in vegetable oil industry. Although each of the foregoing processes has advanced the art, the search continued for the development of membrane based technology of enhanced efficacy which enables to economically process the crude oils. The process comprises diluting the composition with an organic solvent such as hexane, contacting a nonporous membrane under pressure to separate constituents of different molecular weight in the composition into retentate and permeate fractions and recovering the degummed composition from permeate fraction by removing the solvent therefrom. The main object of the present invention is to provide a process for degumming and partial decolori/ation of crude glyceride oils, which obviates the drawbacks of the known processes as detailed above. Another object of the present invention is to produce composition, which will be substantially free from color compounds. Still another object of the present invention is to produce a higher membrane permeate flux (solvent free basis) greater than the permeate flux obtained under undiluted condition. Accordingly the present invention provides a process for degumming and partial decolorization of crude glyceride oils using a hydrophobic nonporous polymeric membrane, comprising the steps of: a) diluting the glyceride composition with hexane, b) characterized in that contacting the said feed with an active surface of hydrophobic nonporous polymeric membrane in nitrogen atmosphere, at a temperature in the range of 20-35°C, at a pressure ranging between 0.5-4.0 M pa under agitation, c) collecting the permeate fraction from the above step and removing solvent by known method to obtain the desired degummed and partially decolorized oil. In an embodiment of the present invention the membrane used is a commercially available hydrophobic nonporous polymeric membrane. In still another embodiment of the non-acidic non-alcoholic arganic solvent used is hexane. The present invention provides a process for degumming and partial decolorization of crude glyceride oils. In the process, the crude glyceride oil is diluted suitably with an organic solvent such as hexane and processed in a flat membrane test cell under nitrogen atmosphere using hydrophobic nonporous polymeric membrane. The cell is charged with a known quantity of hexane diluted crude glyceride oil (miscella) and operated in the batch mode. The polymeric membrane is cut into a circular disc (7.5 cm diameter with 32 cm" effective cross sectional area) and fitted into the test cell along with a porous Teflon support sheet, A Teflon O-ring is used on the membrane surface. The membrane is fitted in the cell in such a way that active surface comes into contact with feed material. The membrane cell is placed on a magnetic stirrer and the magnetic spin bar fitted into the cell provided the agitation. The required operating pressure is applied using pressurized nitrogen gas from a cylinder. The permeate fraction is collected through a port beneath the membrane support. The process is terminated after a predetermined quantity of permeate is collected. Phosphorus contents of the samples of crude and processed oils are measured using AOCS method Ca 12-55 (AOCS, 1994). This method determines phosphorus by ashing the oil sample in the presence of zinc oxide, followed by the spectrophotometric measurement of phosphorus as a blue phosphomolybdic acid complex. Phospholipid equivalent is calculated by multiplying the phosphorus content by a factor of 30. The color of oil samples is determined by Lovibond method of AOCS, Cc 13e-92, using glass cell with an optical path length of 10 mm (AOCS, 1994). Color measurements for soybean oil samples are measured as absorbance values at 454 nm using UV-Visible Spectrophotometer [J. Food Eng., 38:41-56 (1998)]. Absorbance in the visible range is measured in oil samples (after evaporating hexane) using 10 mm cuvette with methylene chloride as blank. These measurements are carried out after suitable dilution to be within the sensitivity range and then the values are normalized for comparison. The percent observed rejection (R during each batch of the experiment using the following Equation. R = ln(Wj/W0 where, C«, and CM are the initial and final contents of each component in the retentates (kg/kg-oil) and W, and WV are the initial and final weights of retentate (kg-oil), respectively. The percent reduction (PR) was calculated using the following Equation. 100(C,.--CP) i rv — "—•—™ ~-— c,, where C(.- and C> are the contents of each component in the crude and the processed oils (kg/kg-oil). The membrane that are suitable are wholly unaffected by glyceride oils and the common nonpolar solvents such as hydrocarbon? which may be used in the invention. The membrane may be used in any forms conventionally adopted where these are appropriate to the membrane material selected. Thus the membrane may be used in plate, tubular or fibre form. The solvent selected is essentially nonaqueous should improve the mobility of the liquid system. The solvent must be non-acidic and non-alcoholic and solvents of low molecular weight with no substantially greater osmotic pressure. The amount of solvent used to dilute the oil is not critical since the object of diluting is to increase the mobility. Preferably a concentration of oil of 10 to 50%(wt.) in the solution is used. The operating conditions, namely temperature, pressure and flow rate are not very critical. For the sake of convenience, temperatures in the ambient range of 20-40°C. are preferably employed. Temperature beyond 55-60°C may soften the polymeric membrane to an unacceptable degree. The pressure applied is from 0.5 to 4.0 MPa and an operating pressure of 0.5 - 2 MPa is usually adequate. The applied pressure does not affect the selectivity of phospholipids since phospholipids are transformed in to larger micelles under the influence of solvents enabling them to be wholly retained by membrane. However, change in pressure may have some effect in the rejection of other impurities (color compounds). The flow rate of the solution is preferably maintained in the turbulent region to minimize concentration polarization of retentate at the membrane surface. Means such as stirrers may be provided to ensure turbulence in batch membrane cells. The invention is particularly suitable for refining crude vegetable oils. The process may also be suitable for the treatment of glycerides of animal sources as well as from other than natural sources. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. EXAMPLE 1 The flat membrane test cell (Model C40-B; Nitto Denko Corporation, Kusatsu, Japan) was charged with 100 g of crude rice bran oil after suitable dilution as shown in Table 1 with hexane. The hydrophobic nonporous polymeric membrane (NTGS-2100, Nitto Denko) was cut into a circular disc (7.5 cm diameter with 32 cm" effective cross sectional area) and fitted into the test cell along with a porous Teflon support sheet. A Teflon Oring was used on the membrane surface. The membrane was fitted in the cell in such a way that active surface comes into contact with feed material. The membrane cell was placed on a magnetic stirrer and the magnetic spin bar fitted into the cell provided the agitation. The stirrer spin bar speed was maintained at 600 rpm. The required operating pressure (1 MPa) was applied using pressurized nitrogen gas from a cylinder. The experiment was conducted in a batch mode at room temperature (27±1°C). The permeate fraction was collected through a port beneath the membrane support. The experiment was stopped when a predetermined quantity of permeate was collected (30 and 40 g for 1:1 and 1:2 oil-solvent ratio, respectively). The results of the experiment are shown in Table 1, Phosphorus contents of the samples were measured using AOCS method Ca 12-55 (AOCS, 1994). Phospholipid equivalent was calculated by multiplying the phosphorus content by a factor of 30. (Table Removed) EXAMPLE 2 The groundnut oil (crude) was processed in a flat membrane test cell under nitrogen atmosphere at room temperature (27±1°C) using hydrophobic nonporous polymeric membrane (NTGS-2100, Nitto Denko) in the batch mode. Operating conditions were maintained as in Example-1. The experiment was stopped when a predetermined quantity of permeate was collected (30 and 40 g for 1:1 and 1:2 oil-solvent ratio, respectively). The results of the experiment are shown in Table 2. Phosphorus contents of the samples were measured using AOCS method Ca 12-55 (AOCS, 1994), (Table Removed) EXAMPLE 3 The mustard oil (crude) was processed in a flat membrane test cell under nitrogen atmosphere at room temperature (27±1°C) using hydrophobic nonporous polymeric membrane (NTGS-2200, Nitto Denko) in the batch mode. Operating conditions were maintained as in Example-1. The experiment was stopped when a predetermined quantity of permeate was collected (30 g). The results of the experiment are shown in (Table Removed) EXAMPLE 4 The soybean oil (industrially water degummed) was processed in a flat membrane test cell under nitrogen atmosphere at room temperature (27±1°C) using hydrophobic nonporous polymeric membrane (NTGS-2200, Nitto Denko) in the batch mode. The required pressure (3 MPa) was applied using pressurized nitrogen gas from a cylinder. All other operating conditions were maintained as in Example-1. The experiment was stopped when a predetermined quantity of permeate was collected (20, 30, 40 and 50 g for 1:0, 1:1, 1:2 and 1:3 oil-solvent ratio, respectively). The results of the experiment are shown in Table 4 Phosphorus contents of the samples were measured using AOCS method Ca 12-55 (AOCS, 1994). Color measurements for oil samples were measured as absorbance values at 454 run using UV-Visible Spectrophotometer. Absorbance was measured in oil samples (after evaporating hexane) using 10 mm cuvette with methylene chloride as blank. These measurements were carried out after suitable dilution to be within the sensitivity range and then the values were normalized for comparison. (Table Removed) EXAMPLE 5 The rice bran oil (crude) was processed in a flat membrane test cell under nitrogen atmosphere at room temperature (27±1°C) using hydrophobic nonporous polymeric membrane (NTGS-2200, Nitto Denko) in the batch mode. The required pressure (3 MPa) was applied using pressurized nitrogen gas from a cylinder. All other operating conditions were maintained as in Example-1. The experiment was stopped when a predetermined quantity of permeate was collected (20, 30,40 and 50 g forl :0, 1:1,1:2 and 1:3 oil-solvent ratio, respectively). The results of the experiment are shown in Table 5. Phosphorus contents of the samples were measured using AOCS method Ca 12-55 (AOCS, 1994). The color of oil samples was determined by Lovibond method of AOCS, Cc 13e-92, using glass cell with an optical path length of 10 mm (AOCS, 1994). (Table Removed) PR, percent reduction; RO, observed rejection; IF, improvement factor. The above examples showed that the process using hydrophobic nonporous polymeric membranes results in practically complete removal of phospholipids (as indicated by the low phosphorus content in the processed oil) and partial reduction of color compounds and substantially lower degree of selectivity towards triglycerides accompanied with an enhanced permeate flux (solvent free basis) across the membrane. The mam advantages of the present invention are: 1. The near complete removal of phospholipids indicated that the membrane process effectively separated not only hydratable but also nonhydratable phospholipids present in the oils. 2. The reduction in color was greater in undiluted oils. The permeate flux was very low in undiluted oils which improved by nearly 10 folds with suitable dilution with hexane. Although the rejection of color compounds were reduced with dilution in organic solvent, still percent reduction of color compounds was significant from the view point of process economics. Considering the amount of clay used in the conventional bleaching process and its associated problems, even partial removal of color to the extent of -50% besides phosphorus reduction will make the membrane process economically attractive. 3. Substantial savings could be achieved since the same membrane would be able to reduce both phospholipids as well as color compounds in a single step. 4. Nonporous membrane processing can be an alternate processing method for degumming and decolorization steps for solvent extracted oils. 5. Nonporous membrane processing may be also used as a single step pretreatment in the physical refining process that offers several advantages over chemical refining process widely used by the industry. We claim 1. A process for degumming and partial decolorization of crude glyceride oils using a hydrophobic nonporous polymeric membrane which comprises the steps of: a) diluting the glyceride composition with hexane, b) characterized in that contacting the said feed with an active surface of hydrophobic nonporous polymeric membrane in nitrogen atmosphere, at a temperature in the range of 20-35°C, at a pressure ranging between 0.5-4.0 M pa under agitation, c) collecting the permeate fraction from the above step and removing solvent by known method to obtain the desired degummed and partially decolorized oil. 2. A process as claimed in the claim 1, wherein the membrane used is a commercially available hydrophobic nonporous polymeric membrane. 3. A process as claimed in the claims 1 & 2, wherein the hydrophobic nonporous polymeric membrane is made of oil and solvent resistant materials. A process for degumming and partial decolorization of crude glyceride oils substantially as herein described with reference to the examples accompanying the specification.

Documents:

1122-DEL-2002-Abstract-(07-09-2009).pdf

1122-del-2002-abstract.pdf

1122-DEL-2002-Claims-(07-09-2009).pdf

1122-del-2002-claims.pdf

1122-DEL-2002-Correspondence-Others-(07-09-2009).pdf

1122-del-2002-Correspondence-Others-(24-12-2009).pdf

1122-del-2002-correspondence-others.pdf

1122-del-2002-correspondence-po.pdf

1122-DEL-2002-Description (Complete)-(07-09-2009).pdf

1122-del-2002-description (complete).pdf

1122-del-2002-form-1.pdf

1122-del-2002-form-18.pdf

1122-del-2002-form-2.pdf

1122-DEL-2002-Form-3-(07-09-2009).pdf

1122-del-2002-form-3.pdf

122-del-2002-Claims-(24-12-2009).pdf

122-del-2002-Description (Complete)-(24-12-2009).pdf