Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11B—PRODUCING, e.g. BY PRESSING RAW MATERIALS OR BY EXTRACTION FROM WASTE MATERIALS, REFINING OR PRESERVING FATS, FATTY SUBSTANCES, e.g. LANOLIN, FATTY OILS OR WAXES; ESSENTIAL OILS; PERFUMES
  • C11B3/00—Refining fats or fatty oils
  • C11B3/001—Refining fats or fatty oils by a combination of two or more of the means hereafter
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11B—PRODUCING, e.g. BY PRESSING RAW MATERIALS OR BY EXTRACTION FROM WASTE MATERIALS, REFINING OR PRESERVING FATS, FATTY SUBSTANCES, e.g. LANOLIN, FATTY OILS OR WAXES; ESSENTIAL OILS; PERFUMES
  • C11B3/00—Refining fats or fatty oils
  • C11B3/02—Refining fats or fatty oils by chemical reaction
  • C11B3/04—Refining fats or fatty oils by chemical reaction with acids

Definitions

• the present invention relates to a process for degumming triglyceride oils.
• Edible oils are triglycerides which have been ex­tracted from animal, marine or vegetable matter. Oils of marine and vegetable origin contain,in addition to the tri­glycerides of fatty acids, extraneous materials, for instance free fatty acids, colour bodies, sterol-type compounds and phosphorus-containing compounds.
• the phosphorus-containing compounds are known in the art as phosphatides, phospholipids or gums. It is necessary in refining triglyceride oils to remove one or more of these components. In particular, it is desirable to reduce the amount of the phospholipids in the oil from an initial concentration of about 500 to 3000 ppm to less than about 3 ppm (based on phosphorus). Oils which contain greater than 1 or 2 ppm phosphorus have an unstable flavour and colour. Also, the presence of phosphorus com­pounds above this level can interfere with subsequent processing of the oils, for instance in the hydrogenation of the oils.
• the phosphatides present in triglycerides are generally thought to be of two types, hydratable phosphatides and hydrolyzable phosphatides.
• the hydratable phosphatides are easily removed from the oil by treatment with water to hydrate the compounds, followed by removal, for example by centrifugal separation. Extractors of triglycerides will often carry out this initial degumming process to produce what is termed in the art, partially or industrially degummed or deslimed oil.
• This industrial degumming process is capable of reducing the phosphorus content of the oil to about 200 ppm. However, this phosphorus level is still too high for any practical application, and the industrially degummed oil must be further refined to remove the remaining phospho­lipids, which are present in a hydrolyzable form.
• the conventional commercial process for degumming triglycerides comprises treating the oil with phosphoric or citric acid, at a temperature of about 60 to 90°C for about 20 minutes, to hydrolyze and hydrate the phosphatides, and subsequently neutralizing the oil with caustic soda to remove the free fatty acids, phospholipids and soaps.
• the neutralization step produces what is called a soapstock, which is a combination of free fatty acids with caustic soda.
• the soapstock and phospholipids are removed by centrifugal separation.
• the oil is bleached with a bleaching clay to remove colour bodies, and then deodorized by steaming to remove odours, flavours and the remaining free fatty acids.
• This conventional process has one major drawback, and that is the production of the soapstock.
• This soapstock is an undesirable waste product which must be further processed prior to disposal.
• the soapstock also carries with it undesirable quantities of entrained oil.
• the usual approach to overcoming the problems of the above-described commercial process is to avoid the neutralization step by practising a more intensive initial degumming step.
• the oil is treated with phos­phoric or citric acid at a temperature of about 90 to 100°C for one hour or more.
• the gums are then removed by centri­fugal separation.
• the oil is subsequently subjected to the bleaching and deodorizing steps.
• the initial degumming step is exemplified only with an acid contacting step which is conducted at very high temperatures, typically at 70°C.
• a triglyceride oil can be efficiently and economically degummed by dispersing in the oil an organic acid or acid anhydride, at a temperature not greater than about 40°C, subsequently dispersing water in the oil, while maintaining this temperature, and then separating a sludge containing the gums from the oil.
• This process is effective in reducing the phosphorus content in the oil, at this stage in the refining to less than about 15 ppm.
• the inventors have further discovered that, surprisingly, the oil product of the degumming process of the invention, when subjected to the further step of bleaching, consistently results in a refined oil product containing substantially less than 3 ppm phosphorus.
• the phosphorus reduction after bleaching is typically less than about 1 ppm and usually less than about 0.5 ppm.
• the degumming process of this invention results in a conditioning of the phosphorus-­containing compounds in the oil, which makes them readily adsorbable on bleaching clay and therefore more completely removable in the subsequent bleaching operation. It is further believed that the phospholipids in the oil, once they are hydrolyzed and hydrated by this process are less oil-­soluble at the lower temperature conditions of this process, and are therefore more completely removable than if the process were conducted at a higher temperature.
• the process of this invention when practiced in combination with a bleaching step, is capable of reducing the phosphorus content to at least the same level as that of the conventional alkali refined and bleached oil.
• the process of this invention achieves this result without the production of the undesirable soapstock and the loss of oil entrained in the soapstock.
• this result is achieved without the necessity of maintaining a high temp­erature during the acid contacting step.
• the oil product produced by the process of this invention leaves the free fatty acids in a relatively stable form such that they can be removed and recovered in a subsequent deodoriz­ation and fatty acid stripping step comprising steam distil­lation.
• the present invention broadly provides a process for degumming a triglyceride oil which is substan­tially liquid at about 40°C, comprising (a) dispersing in the oil an organic acid or acid anhydride, at a temperature not greater than about 40°C; (b) subsequently dispersing water in the oil, while maintaining the temperature at not greater than about 40°C; and then (c) separating a sludge containing the gums from the oil to produce an oil product substantially reduced in phosphorus-containing compounds.
• the triglyceride oils commonly used as feedstocks in this process include edible oils of vegetable or marine origin obtained by any of the known extraction techniques, including pressing and solvent extraction from an appropriately prepared oilseed or solvent extraction from a residue of a pressing operation.
• the oil may also be an oil prepared by rendering, pressing or solvent extraction from a whole marine species or a part thereof.
• feedstocks may be used in their crude form, but will usually be received from a com­mercial extractor of these oils in a partially degummed (industrially degummed) form, wherein the hydratable phospho­lipids have been substantially removed.
• the oil feedstock will be substantially liquid at the temperatures used in this process, which are less than about 40°C.
• the steps wherein the oil is contacted with an organic acid or acid anhydride are conducted at a temperature not greater than about 40°C.
• the phosphorus removal achieved by the process drops off significantly.
• the lower temperature limit in these steps is generally set by the phys­ical characteristics of the oil feedstock.
• the oil should be substantially liquid at the process temperature.
• the preferred temperature of the process is in the range of about 20-25°C. In this ambient temperature range the oil does not require heating or cooling throughout the process.
• Certain triglyceride oils for example corn and sunflower oil, contain undesirable waxes when such oils are chilled. These waxes precipitate, giving the oil a cloudy appearance. Also, the waxes deteriorate at high temperature processing, deliteriously affecting the stability of the final product. Such oils are usually subjected to a procedure known as winterization, wherein the oil is cooled to crystal­lize the waxes and then cold filtered to remove the waxes.
• triglyceride oils containing waxes can be simultaneously dewaxed and degummed by maintaining the temperature throughout the degumming process in the range of about 0 to 10°C.
• the organic acid, and thereafter the water are dispersed in the oil, and the sludge is separated from the oil at a temperature of about 0 to 10°C.
• the sludge which is removed from the oil contains both the phosphorus-­containing gums and the majority of the waxes.
• the acid-oil mixture is preferably maintained under agitation for a time sufficient to hydrolyze the majority of the hydrolyzable phospholipids.
• the time needed for this step will vary with the particular oil and the temperature being used, but will usually be less than about one hour, and will preferably be 10 to 20 minutes.
• the organic acid or acid anhydride used in this process will most preferably be citric acid or maleic anhyd­ride, and will preferably be of food grade quality.
• Other acids comparable to citric acid and maleic anhydride, and suitable for use in this process include maleic acid, lactic acid, oxalic acid and acetic anhydride.
• the acid is preferably added as an aqueous solution containing an amount of the acid up to the saturation point. A 50% by weight aqueous solution of the acid is preferred.
• the amount of acid added to the oil will vary with the type of oil being processed, the amount and type of impurities in the oil and the other process conditions. Typically, an amount from about 1,000 to 10,000 ppm (0.1 to 1.0% by weight) of the oil, calculated on the basis of dry acid, is sufficient for the process.
• water is dispersed in the oil while maintaining the temperature at not greater than about 40°C.
• the amount of water needed in this step will vary with the quantity of phospholipids in the oil, but an amount in the approximate range of 0.1 to 3% by weight of the oil will usually be sufficient. An amount of water in the range of about 1.5 to 2.5% by weight of the oil is preferred.
• the oil, acid and water mixture is preferably maintained under agitation for a time sufficient to hydrate the majority of the phospho­lipids.
• the time will vary with the type of oil and temperature, but will usually be less than about one hour, and will preferably be about 20 to 30 minutes.
• the phospholipids Once the phospholipids have been hydrated they become oil insoluble and precipitate out of the oil in the form of an aqueous sludge.
• This sludge is separated from the oil, preferably by centrifugation in a manner well known in the art. For practical reasons, the centrifugation is preferably carried out at a temperature not greater than about 35°C. After separation, the oil product is typically found to have a phosphorus content of less than about 15 ppm.
• the process of this invention may be carried out either as a batch process or as a continuous process.
• the oil product produced by this process is in a suitable form for further treatment by the known procedures of bleaching, deodorization and free fatty acid stripping.
• the oil product resulting from the process of this invention after subsequent bleaching has a very low level of residual phosphorus, typically less than 1 ppm.
• the oil product may be neutralized in accordance with the known neutralization techniques, however, this step is preferably omitted in order to avoid the production of the undesirable soapstock.
• This example shows the effect of temperature on the process of this invention.
• the degummed oil was thereafter decolorized with bleaching clay and acid and then deodorized, in accordance with the following procedures:
• the degumming process of this invention is capable of significantly reducing the phosphorus content of the oil. While the phosphorus content is still higher than desirable after the initial removal of the sludge, following the decolourization of the degummed oil, an oil product very low in phosphorus is produced, provided the temperature of the initial degumming process was not greater than about 40°C. The best results with respect to phosphorus removal were achieved when the degumming process was conducted at a temperature not greater than 35°C.
• the mixture was then filtered to remove the sludge containing the gums.
• the oil product was analyzed for phosphorus and free fatty acid content. For comparison purposes, the same oil was degummed with water only (3.0% by weight) with agitation for 30 minutes at 60°C. The analyses of the three filtered products are shown in Table II
• the degummed oil was thereafter decolourized with bleaching clay and acid addition and then deodourized by the following procedures:
• CAMPRO is a trade mark of Cambrian Processes Limited of Mississauga, Ontario, Canada.
• Temperature 255°C Pressure 0.5 to 1.0 mm Hg Time 60 minutes Steam Sparge 3% by weight of the oil Cooling under vacuum
• the degumming process was capable of reducing the phosphorus level to about 10 to 24 ppm. This level was further reduced, after decolourizing, to less than 0.20 ppm. The reproducibility of the phosphorus removal, colour, free fatty acid removal and flavour was excellent.
• the degummed oil was then dried at 60-70°C under -27 ⁇ Hg for one hour in the reactor.
• the degummed oil (1,5001 collected) was pumped into a 26001 jacketted reactor and from this 3001 of degummed oil was mixed with PEMBINA VEGA clay bleaching earth to prepare a 3% clay slurry based on the total oil.
• PEMBINA VEGA is a trade mark of Pembina Mountain Clays Incorporated of Winnepeg, Manitoba, Canada.
• To the remainder of the oil was added, with mixing, 500 ppm each of phosphoric and citric acid (as solutions).
• the oil-acid mixture was heated under vacuum to 100°C with agitation.
• the clay slurry was then added to this mixture, also at a tempterature of 100°C
• the total mixture was heated to 110 to 115°C and held for 15 minutes at -27 ⁇ Hg.
• the bleached oil was cooled with a heat exchanger to 60°C and then filtered in a filter press.
• the analytical results of the decolorization are shown in Table V.
• the bleached oil was thereafter deodorized by steam refining with a CAMPRO pilot deodorizer under the following conditions: Oil flow rate 700-750 lbs/hr Steam sparge 21 lbs/hr Vacuum 3 mm Hg Temperature 257-260°C
• the following example illustrates the simultaneous degumming and dewaxing of a triglyceride oil contining waxes.
• the degummed oils were then decolourized by adding phosphoric and citric acid (500 ppm each) at room temperature, followed by the addition of 3% by weight bleaching clay at 90°C.
• the bleaching was conducted at 110-115°C for 15 minutes under reduced pressure. The results are shown in Table VI.
• the decolourized oil was thereafter deodorized at 225°C for 60 minutes.
• the steam sparge in this step was approximately 3%/hr.
• a cold test was conducted on the deodorized oil to examine for wax removal. The results are shown in Table VI.

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• 1987
  • 1987-10-29 EP EP19870309597 patent/EP0269277B1/fr not_active Expired
  • 1987-10-29 DE DE8787309597T patent/DE3771670D1/de not_active Expired - Lifetime
  • 1987-11-04 DK DK579887A patent/DK579887A/da not_active Application Discontinuation
  • 1987-11-13 JP JP28760487A patent/JPS63191899A/ja active Pending

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