WO2017058585A1 - Degumming - Google Patents

Abstract

Methods are provided for degumming renewable source derived oils, the method comprising contacting the oils with at least one tetrahydroxy carboxylic acid derived from an aldohexose. In selected embodiments, after degumming, the oil is subjected to at least one of refining, bleaching, and deodorizing. The ratio of the anisidine value of the refined, bleached, and deodorized oil obtained after contacting the oil with at least one tetrahydroxy carboxylic acid derived from an aldohexose to the anisidine value of the crude oil is, in certain embodiments, not greater than 1.2.

Description

DEGUMMING

FIELD OF THE INVENTION

[0001 ] The present invention relates to purification of renewable source-derived oils by removing phospholipids from the oil in a degumming step using a tetrahydroxy carboxylic acid derived from an aldohexose.

BACKGROUND OF THE INVENTION

[0002] Most renewable source derived oils primarily consist of triglycerides, also termed triacylglycerols. In addition to triglycerides, however, renewable source derived oils also contain several other compounds. Some of these additional compounds, such as mono- and di-glycerides, tocopherols, sterols, and sterol esters, need not necessarily be removed during processing. Other compounds and impurities such as phospholipids (phosphatides, gums), free fatty acids, odiferous volatiles, colorants, waxes, and metal compounds negatively affect taste, smell, appearance and storage stability of the refined oil, and hence must be removed.

[0003] The triglycerides of renewable source derived oil are fatty acid esters of 1,2,3-propane triol. The fatty acids are selected from the group consisting of C4-C28 saturated, unsaturated, and polyunsaturated fatty acids. For example, crude soybean oil typically contains from about 95 to about 97 percent by weight triglycerides. In soybean oil the saturated fatty acids that can occur include but are not limited to lauric (C12:0), myristic (C14:0), palmitic (C16:0), stearic (C18:0), arachidic (C20:0), and behenic (C22:0) acids. Generally, however, the fatty acids of soybean oil are predominantly unsaturated, and include but are not limited to oleic (C18: l), linoleic (C18:2), and linolenic (C18:3) acids. Microbial oils, such as algal oils, and fish oils may contain these fatty acids as well as polyunsaturated fatty acids, including arachidonic (C20:4) acid, eicosapentaenoic (C22:5) acid, docosapentaenoic (C24:5) acid, or docosahexaenoic (C24:6) acid. Unsaturated fatty acids can exist as geometric and/or positional isomers, each such isomer having different properties such as melting point. Naturally occurring fatty acids generally exist in the cis form but they can be converted into the trans form during the course of purification steps used to produce a vegetable oil from an oilseed.

[0004] Vegetable oils are typically obtained by pressing or solvent extracting the oil seeds of plants such as com or soybeans to obtain crude oil. The process of converting crude oil into edible oil is called "Refining." However, the fatty acid removal step in a Refining process is also called "refining." Most Refining operations employ either alkali refining (also termed caustic refining) or physical refining (also termed steam refining). Of these two refining methods, alkali refining predominates.

[0005] In Refining with an alkali refining step, impurities may be removed from crude renewable source derived oil in four distinct steps of degumming, alkali refining, bleaching, and deodorizing. Of these four steps, degumming removes the bulk of hydratable phosphatides. Alkali refining primarily removes fatty acid soaps created from the neutralization of free fatty acids, non-hydratable phosphatides (NHP), and other impurities such as metals. In alkali refining, free fatty acids, phospholipids, and metals are removed from crude or degummed oil by mixing the oil with a hot, aqueous alkali solution, producing a mixture of so-called neutral oil and soapstock (also termed refining byproduct lipid). Soapstock is an alkaline mixture of saponified free fatty acids and gums. The neutral oil is then separated from the soapstock, typically by centrifugation. The soapstock has commercial value due to its fatty acid content but must be processed further in order to render it salable. The neutral oil is further processed by bleaching to remove residual soap. One drawback of Refining by alkali refining is that the non-hydratable phosphatide fraction is destroyed and converted into materials that pass into the soapstock, so only the hydratable phosphatides can be recovered in the gums.

[0006] Bleaching is the next step in Refining, and improves the color and flavor of oil by decomposing peroxides and removing oxidation products, trace phosphatides, color bodies, and trace soaps by contacting the oil with bleaching solids. Soybean oil bleaching materials include neutral earth (commonly termed natural clay or fuller's earth), acid-activated earth, activated carbon, and silicates. Deodorizing is the final processing step in Refining and prepares the oil for use as an ingredient in many edible products including salad oils, cooking oils, frying fats, baking shortenings, and margarines. The deodorizing process generally comprises passing steam through refined oil at high temperature and under near vacuum conditions to vaporize and carry away objectionable volatile components.

[0007] An alternative to Refining by alkali refining is Refining by physical refining. In Refining by physical refining (also termed steam refining), fatty acids are removed from oil by evaporation and steam sparging under vacuum. This process is often carried out on the so-called tropical oils, such as palm oil and coconut oil. Refining by physical refining is a steam distillation process essentially the same as that used in the deodorization step of Refining by alkali refining, in which steam is passed through the oil under vacuum to vaporize and carry away free fatty acids. The main advantage of Refining by physical refining over Refining by alkali refining is that no soapstock is generated. A second advantage is that oil losses are lower because there is no saponification of oil and no oil entrainment and/or emulsification by soapstock. Accordingly, there is significant interest in Refining by physical refining due to its economic advantages and friendliness compared to Refining by alkali refining. But because Refining by physical refining does not remove NHPs, any oils to be Refined by physical refining must be relatively free of NHPs in order to ensure stable refined oils. Oils such as palm oil and tallow, which have low NHP content, can be successfully Refined by physical refining. The Refining by physical refining process has several drawbacks, however. Oils such as soybean oil and sunflower seed oil, which are relatively high in NHPs, are not commonly Refined by physical refining because the typical pre- physical refining step of water degumming does not remove NHPs from soybean oil and similar oils.

[0008] The terms phosphatides and phosphatide concentrates are commonly used to refer to a mixture of phospholipids comprising phosphatidyl derivatives which are present in crude renewable source derived oil. Such phosphatides also are referred to as gums. One obj ective of refining renewable source derived oil is to reduce the phospholipid content in the oil. Phospholipids interfere with oil refining, reduce oil performance and flavor stability in many applications and are particularly troublesome in frying oil. Carefully separated, however, phospholipids are valuable raw materials as a source of lecithin emulsifiers. Phospholipids in oil are easily quantified by measuring the level of phosphorus in oil, and are typically derived by the following equation:

Percent Phospholipids = ((Phosphorus in oil (PPM) x 31.7) x 10⁴).

[0009] For either Refining method, an optional but preferred first step is a conventional water degumming process. Degumming refers to the process of removing hydratable phosphatides and some water-soluble impurities from crude renewable source derived oil. A simple water degumming process comprises admixing demineralized water with the crude oil and separating the resulting mixture into an oil component and an oil- insoluble hydrated phosphatides component by a convenient method such as by gravitational force or by centrifugal separation. The hydrated phosphatides component is frequently referred to as a "wet gum" or "wet lecithin". Phosphatide concentrates coming from centrifugal separation will sometimes contain up to about fifty percent by weight water, and typically will contain from about twenty-five to about thirty percent by weight water. In order to minimize chances of microbial contamination, phosphatide concentrates must be dried or otherwise treated immediately. Dried phosphatide concentrates can be profitably sold as commercial lecithin

[0010] Upon being dried, phosphatides generally are termed lecithin or commercial lecithin. Crude soybean oil in particular provides the chief source for commercial lecithin. The term lecithin may refer to phosphatidyl choline. However, as generally used by commercial suppliers, the term lecithin refers to a product derived from renewable source derived oils, especially soybean oil. Specific chemical components of phosphatides present in renewable source derived oil include phosphatidylcholine, phosphatidyl ethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidic acid, cyclolipids, and other components such as free sugars, metals and free fatty acids. Phospholipids are amphipathic, i.e. one end of the molecule is hydrophilic (lipophobic) and the other end is hydrophobic (lipophilic). As a result, they possess useful surface- active properties, and can orient in aqueous environments to create membranes and bilayers. The fatty acid profile of phosphatides generally matches that of the renewable source derived oil from which the phosphatides are derived. The phosphatide content of vegetable oil will vary based on a number of factors, including but not limited to oilseed type, seed quality, and the process by which oil is extracted therefrom. Crude soybean oil in particular typically contains from about 1.5 to about 3 percent by weight phosphatides. Phosphatides comprise both hydratable phosphatides and non-hydratable phosphatides ( HPs). Although non-hydratable phosphatides tend to remain oil-soluble and are largely unaffected by water, hydratable phosphatides when hydrated become greater in density than the triglycerides and precipitate, or settle out. This phenomenon forms the basis for the process of conventional water degumming. Degummed oil is further refined to remove NHPs and other unwanted compounds.

[0011] Nonhydratable phospholipids (NHPs), generally considered to be calcium and magnesium salts of phosphatidic acids, are largely unaffected by water and remain soluble in the oil component. Phosphatidic acid in oil is typically produced via the action of phospholipases to hydrolyze fatty acids from phospholipids. The phospholipases are enabled to come into contact with phospholipids upon damage to the cellular structure. Typical metals include calcium, potassium, magnesium, aluminum, iron and copper. Left in place, these metal impurities form salts of phosphatidic acid, thereby contributing to the NHP content. Removal of the metals allows NHP to be converted to the more easily removed hydratable phospholipids. Moreover, metal contaminants, especially iron, can darken oil during deodorization, and even small amounts of iron that can dramatically reduce the stability of refined oil.

[0012] Chelating agents, such as EDTA, may be contacted with oil during or after degumming processes to remove metal compounds from crude renewable source derived oil, allowing the NHP to become more water-soluble.

[0013] Acid also is sometimes added in a degumming process to help minimize the NHP content of degummed oil by dissociating complexes of metal and NHP; this step is sometimes called "acid degumming." A similar process for contacting oil with acid is called "acid conditioning;" acid conditioning is used primarily with coconut oil and palm oil in preparation for Refining by physical refining. Yet another process, "superdegumming," involves the use of acid and water as in acid degumming, but a small amount of alkali may be added with the water to help flocculate the gums. Employing mineral acids during degumming can reduce the overall NHP content prior to alkali treatment by converting the NHPs into water-soluble forms, thus potentially increasing the percentage recovery of the overall phosphatide fraction. For example, the acid in any of these processes may remove calcium or magnesium salts from complexes with phosphatidic acid, rendering it hydratable and enabling phosphatidic acid to migrate from the oil to the water phase, thus eliminating them from the crude oil. However, using mineral acid during degumming acid will cause darkening of the lecithin.

[0014] Thus, there is a significant need for degumming procedures that can reduce the content of NHPs in renewable source derived oil for subsequent Refining by physical refining or by Refining by alkali refining, bleaching and deodorizing. As discussed herein, the incorporation of acid into the degumming process can convert nonhydratable phospholipids into a more hydratable form. The present disclosure teaches means for converting NHP into a more hydratable form while avoiding the drawbacks associated with mineral acids by using an organic acid. [0015] A large number of substances have been tested for degumming renewable source derived oils and are summarized in Table 1. The related references are provided in Table 2. Table 1. Degumming agents reported in literature and patents.

Degumming agent Reference No.

Acetic acid 1 , 1 1 , 19, 34, 35, 37, 38

Acetic anhydride 1 , 18, 20, 31

Acid (unspecified) 13, 14

Aconitic acid 17

Adipic acid 17

Ammonium acetate 12

Ammonium chloride 12

Ammonium hydroxide 1

Ascorbic acid 1

Barium chloride 12

Benzene 16

Boric acid 1 , 1 1 , 12

Butyric anhydride 18

Calcium chloride 12

Calcium thiocyanate 12

Casein 1

1 , 2, 3, 7a, 8, 12, 15, 17, 17a, 19, 20, 22, 24,

Citric acid

26, 30, 31 , 32, 33, 34, 35, 36, 37, 38

Dichloroethylene 16

Dimethyl succinic acid

18

anhydride

Disodium hydrogen

31

phosphate

EDTA 33, 36

EDTA salt 7, 33

EDTA salt + alkali hydroxide 7

Food-grade acid 30, 34, 35, 37, 38

Formaldehyde 1

Formic acid 1

Food acid 30

Food acid anhydride 30

Fumaric acid 17

Gasoline 16

Glucono-6-lactone 1

Glutaric acid 1 , 17 Glycine 1 , 31

Hexane 16

Heptane 16

Hydrochloric acid 1 , 4, 12, 26, 31 , 36

Hydrochloric acid in milk 1

Hydrogen peroxide 1

Hydrogen peroxide +

1

ammonium hydroxide

Hydratable phospholipid +

20

electrolyte

Hydrolyzed lecithin 32

Hydrolyzed phosphatides +

22

water

Itaconic acid 17

Lactic acid 19

L-Alanine 1

L-Aspartic acid 1

L-Glutamic acid 1

L-Lysine HCI 1

Magnesium sulfate 12

Maleic acid 1 , 7a, 15, 17, 17a, 36

Maleic anhydride 1 , 3, 18

Malic acid 7a, 17, 17a, 36

Maltose 1

Milk 1

Monomethyl succinic acid

18

anhydride

Nitric acid 1 , 5

Oxalic acid 1 , 7a, 15, 17, 17a, 24, 33, 36

Pentane 16

Petroleum ether 16

1 , 6, 8, 9, 10, 1 1 , 21 , 22, 24, 26, 31 , 33, 34,

Phosphoric acid

35, 36, 37, 38

Phosphorus acid 19

Picric acid 15

Potassium chloride 1 , 31

Potassium dihydrogen

31

phosphate

Potassium sulfate 12

Potassium tartrate 12

Propionic acid 1

Propionic anhydride 18, 19

Silica gel + acetic acid 23, 25, 27, 28 Silica gel + Ascorbic acid 23, 25, 27, 28

Silica gel + citric acid 23, 25, 27, 28

Silica gel + tartaric acid 23, 25, 27, 28

Sodium bisulfate 11

Sodium borate 11, 31

Sodium chloride 1, 12, 31

Sodium citrate 1

Sodium hexametaphosphate 1

Sodium hydroxide 12, 31

Sodium metaphosphate 1

Sodium metasilicate 1

Sodium nitrate 1

Sodium oxalate 1

Sodium phosphate 11

Sodium potassium tartrate 1

Sodium sulfate 1, 11, 12

Sodium thiosulfate 12

Sodium tripolyphosphate 1

Solid Lewis acid catalyst +

29

water

Soluble starch 1

Succinic acid 1, 1734, 35, 37, 38

Succinic anhydride 1, 18

Sucrose 1

Sulfamic acid 1, 15

Sulfuric acid 1, 11, 12, 31, 36

Tannic acid 1

Tartaric acid 1, 12, 17, 17a, 19, 24, 3334, 35, 36, 37, 38

Tetrasodium pyrophosphate 1

Tricarballylic acid 17

Trichloroacetic acid 1

Trichloroethylene 16

Triethanolamine 11

Tween 80 1

Urea 1

Water 1, 11

Wheat flour 1

Wheat flour + Hydrochloric

1

acid Table 2. References for Table 1.

[0016] Phosphoric acid is often used as a standard acid in industrial scale degumming of renewable source derived oils. Citric acid is also widely used in degumming; both of these acids have been the subject of many studies and reports (Table 1). Lecithin obtained by degumming with edible acids, such as acetic acid, citric acid, tartaric acid, lactic acid, etc., can be used as animal feedstuff, and to prepare emulsifiers for the food industry. However, citric acid supplies may be interrupted, and the cost of citric acid may be unstable. In addition, the citric acid is produced by batch fermentation, requiring significant investment in equipment. The purification of citric acid produced by fermentation requires a change in pH, and significant amounts of calcium sulfate byproduct are generated. The separation of calcium sulfate from the citric acid requires an additional significant investment, ongoing operating costs and disposal costs. These disadvantages of citric acid underscore the need for alternative acids suitable for degumming.

[0017] The double bonds of renewable source derived oil are sensitive to reactions, such as oxidation. Thus, lipids, such as oils, fats, fatty acids, partial glycerides, esters, phospholipids, and other compounds that contain double bonds are susceptible to oxidation reactions. Lipid oxidation is a reaction that may occur between unsaturated lipids and oxygen, and is accelerated by several factors (light, heat, metals, and other initiating compounds). The consequence of lipid oxidation is often the generation of undesired reaction products. Many reaction products give rise to undesirable odors or flavors in edible oils and fats, as well as products made therefrom. Because of the complexity of natural oils and the large number of possible reaction pathways for a given oxidation reaction, oxidation reactions are incompletely understood. However, some are known to proceed in a radical chain reaction cascade fashion comprising several steps. Natural oils differ in their composition, and thus in their oxidation pathways. Antioxidants are commonly added to lipids to delay the onset of oxidative deterioration. In addition, oils can be stored under an inert gas, such as nitrogen or a noble gas, to minimize oxidation. Sometimes, inert gases are bubbled through oils to displace the small amounts of oxygen in the oil. Oxidative deterioration of oils which undergo storage is a common phenomenon, and limits the useful lifetime of the oil. Oil obtained from oilseeds which have been stored for a substantial period of time after harvest is often higher in oxidation products that oil from seeds obtained from freshly harvested oil.

[0018] In the first step of lipid oxidation, double bonds react with oxygen to form allylic hydroperoxides (also known as peroxides). Because they originate from a first step of oxidation, hydroperoxides are considered to be primary oxidation products. They are routinely quantified by a standardized peroxide value test. One standardized test for peroxide values is AOCS method Cd 8b-90. Good quality oil, which is relatively bland in flavor and low in odor, will generally have a low Peroxide Value (PV). The PV of food oils delivered to food processors is often requested to fall below a specified value to ensure that the foodstuffs produced will be of high quality.

[0019] Peroxides are unstable and readily undergo further reactions. A low PV is not the only marker for good oil quality, because the PV of an oil may reach a high level and then decline as oxidation advances and peroxides are further broken down into so-called secondary oxidation products which reduce oil quality. The breakdown of peroxides is complex and incompletely understood, the number of possible secondary oxidation compounds is large, complex, and incompletely classified, and the analysis of secondary oxidation products can be difficult. Although many high molecular weight unsaturated lipids have no distinctive flavor themselves, their breakdown compounds have intense flavors, which affect the quality and stability of oils. Some secondary oxidation products, such as aldehydes, carbonyls, ketones, alcohols, acids, esters, ethers, hydrocarbons, and lactones, are of lower molecular weight than the original lipid, and thus are more volatile than the starting lipid and peroxides. These secondary oxidation products are problematic in the edible oil industry. Many of these compounds can be tasted or smelled even at very low concentrations and have potent, often undesirable odors or flavors which detract from the quality of edible oil or food made therefrom. Secondary oxidation products are at least partially measured by the Anisidine Value. This important marker of oil quality is usually part of trade specifications and is determined by an Anisidine Value Test, such as AOCS Cd 18 (97). Anisidine value tests measure carbonyls formed from lipid oxidation, such as 2-alkenals and 2, 4 dienals. In addition, oxidative dimers of triglycerides, aldehyde-glycerides, and core aldehydes are known to contribute to high anisidine values. During refining, bleaching, and deodorization, the thermal decomposition of peroxides causes an increase in the anisidine value of oil. Thus, the anisidine value of refined, bleached, deodorized oil is higher, as a rule, than the anisidine value of the corresponding crude oil before refining, bleaching, and deodorizing (J. Amer. Oil Chem. Soc. 51(2) 17-21, 1974). The relationship between the anisidine value of crude oil and the corresponding refined, bleached deodorized oil may be expressed as a numerical ratio. For example, in their ground-breaking paper on characterizing soybean oil oxidation with the Anisidine Test, List et al. (J. Amer. Oil Chem. Soc. 51(2) 17-21, 1974) documented the relationship between anisidine values, peroxide values, and flavor scores of soybean oil samples. They showed that for an oil from sound quality soybeans, the anisidine value of the crude oil by extrapolation of Fig. 4 was about 0.5, and the anisidine value of the refined, bleached, deodorized oil was about 2.25. Thus, the ratio of anisidine value of crude oil to the anisidine value of the corresponding refined, bleached deodorized oil was about 2.25/0.5, or about 4.5.

[0020] Lipid oxidation often takes place in lipids upon storage. Antioxidants may delay the onset of lipid oxidation for a period of time. In addition, lipid oxidation may occur in oilseeds on storage. Thus oil extracted from seeds which have been stored for more than three months after harvest season is often higher in oxidation products than oil extracted from seeds obtained early in a harvest season. As the seed ages in storage, oxidative indicators, such as anisidine value, may rise. Oil made from seed which has been stored for greater than three months may have deteriorated, and have unacceptably high levels of oxidation products.

[0021 ] Great care to prevent oxidation is taken in edible oil Refining, and proper degumming is an important first step.

[0022] Recent breakthroughs in catalyst technology have enabled the production of the tetrahydroxy carboxylic acid (such as glucaric acid) by a simple oxidation of an aldohexose, such as the carbohydrate glucose. Such oxidations can be carried out in small continuous reactors. Such a process is disclosed in United States Patent Application Publication No. US2013158255, published June 20, 2013. The catalytic oxidation step produces glucaric acid and derivatives such as mono-carboxylic acid intermediates and other di-carboxylic acid side products, and some unreacted glucose may be present. Some gluconic acid may be present as a by-product in the reactor product. The glucaric acid may be substantially pure or may exist in a mixture that includes any amount of one or more derivatives of glucaric acid. Similarly, the one or more derivatives may be substantially pure or may include any amount of one or more derivatives of glucaric acid and/or glucaric acid itself. Derivatives of glucaric acid include "glucarolactones," which include mono- or di-lactones of glucaric acid such as D-glucaro- 1,4-lactone, D-glucaro-6,3-lactone, and D-glucaro-l,4:6,3-dilactone. Other derivatives include salts, esters, ketones, and halogenated forms of glucaric acid. The glucaric acid stream can be continuously and cheaply purified by simulated moving bed chromatography. In addition, a common oxidation by-product of glucose oxidation is gluconic acid; complete removal of gluconic acid by-product from a glucaric acid produced by oxidation of an aldohexoae is not necessary to generate a suitable degumming acid as the gluconic acid does not interfere with degumming the oil.

SUMMARY OF THE INVENTION

[0023] The present invention relates to methods for removing phospholipids from renewable source derived oils, such as triglyceride oils, in the degumming step of edible oil refining. The present invention concerns, in a first aspect, a method for degumming oils using at least one polyhydroxy acid obtainable by oxidation of an aldohexose. In an embodiment, the polyhydroxy acid obtainable by oxidation of an aldohexose comprises a tetrahydroxy organic acid. The polyhydroxy acid obtainable by oxidation of an aldohexose can comprise a combination of at least one tetrahydroxy carboxylic acid and at least one pentahydroxy carboxylic acid.

[0024] We have found that, surprisingly, degumming crude oil with a tetrahydroxy carboxylic acid provides a degummed oil, which, when subsequently refined, bleached and deodorized, is of an unexpectedly low anisidine value. Further, we have found that the anisidine value is sufficiently low that that ratio of the anisidine value of the refined, bleached, deodorized oil to the anisidine value of the starting crude oil is unexpectedly low.

DETAILED DESCRIPTION OF THE INVENTION

[0025] As used herein, by the term "bringing into contact" is meant any type of bringing into contact which is known by a person skilled in the art to be suitable for the purpose according to the invention. In an embodiment, the composition to be degummed is preferably brought into contact with a tetrahydroxy carboxylic acid by stirring or mixing. For details of the industrial implementation of a degumming process, reference may be made to "Practical Guide to Vegetable Oil Processing", Chapter 3, "Crude Oil De-Gumming and Acid Pre-treatment", AOCS Press, p. 33 (2008).

[0026] As used herein, by the term "aldohexose" is meant a monosaccharide having six carbons, an aldehyde functional group at CI, and the chemical formula CeHuOe. Aldohexoses include glucose, galactose, mannose, allose, altrose, idose, gulose, and talose.

[0027] As used herein, the overall process of converting crude oil into edible oil is called "Refining." However, the fatty acid removal step in the process is also generally called "refining" in common usage but the step is distinguished from "Refining" herein by referring to "alkali refining" or "physical refining."

[0028] As used herein, by the term "aldaric acid" is meant a member of the class of compounds polyhydroxy acid obtainable by oxidation of an aldohexose by oxidation of the aldehyde group of the aldohexose to a carboxylic acid and oxidation of the terminal primary alcohol of the aldohexose to a carboxylic acid. Aldaric acids are also called "saccharic acids." For example, oxidizing both the aldehyde group of glucose and the terminal primary alcohol (hydroxy) group to carboxylic acids produces the tetrahydroxy acid, glucaric acid. Aldaric acids include glucaric acid, saccharic acid, galactaric acid, mucic acid, mannaric acid, allaric acid, altraric acid, idaric acid, gularic acid, and talaric acid. Aldaric acids are tetrahydroxy carboxylic acids.

[0029] As used herein, by the term "uronic acid" is meant a member of the class of compounds comprising both aldehyde and carboxyl groups, such as polyhydroxy acid obtainable by oxidation of an aldohexose by oxidation of a hydroxymethyl group to a carboxylic acid while retaining an aldehyde functional group. Uronic acids include glucuronic acid, galacturonic acid, mannuronic acid, alluronic acid, altruronic acid, iduronic acid, guluronic acid, and taluronic acid. Uronic acids are tetrahydroxy organic acids.

[0030] As used herein, by the term "aldonic acid" is meant a member of the class of compounds comprising polyhydroxy acid obtainable by oxidation of an aldohexose by oxidation of the aldehyde group of an aldohexose to a carboxylic acid. For example, oxidizing the aldehyde group of glucose (dextrose) to a carboxylic acid produces gluconic acid. Aldonic acids include gluconic acid, galactonic acid, mannonic acid, allonic acid, altronic acid, idonic acid, gulonic acid, and talonic acid, and isosaccharinic acid. Aldonic acids readily form lactones in solution. Aldonic acids are pentahydroxy organic acids and may be present as a by-product in a mixture comprising tetrahydroxy organic acids obtainable by oxidation of an aldohexose.

[0031] In a first aspect, a method for degumming renewable source derived oils comprising contacting the oil with a tetrahydroxy organic acid obtainable by oxidation of an aldohexose is disclosed. In an embodiment, the acid comprises at least one of an aldaric acid or a uronic acid. In selected embodiments, the aldaric acid comprises at least one of glucaric acid, saccharic acid, galactaric acid, mucic acid, mannaric acid, allaric acid, altraric acid, idaric acid, gularic acid, or talaric acid. In another embodiment, the uronic acid comprises at least one of glucuronic acid, galacturonic acid, mannuronic acid, alluronic acid, altruronic acid, iduronic acid, guluronic acid, or taluronic acid.

[0032] In an alternative embodiment, the aldohexose is selected from the group consisting of glucose, galactose, mannose, allose, altrose, idose, gulose, talose, and combinations of any thereof.

[0033] In still another embodiment, the renewable source derived oil comprises at least one of animal oil, algal oil, microbial oil, plant oil, or vegetable oil. In another embodiment, the renewable source derived oil is crude renewable source derived oil. [0034] In still another embodiment, the aldaric acid comprises glucaric acid and lactones thereof. In yet another embodiment, the aldonic acid comprises gluconic acid and lactones thereof.

[0035] In another embodiment, the oil obtained by contacting crude renewable resource derived oil with at least one tetrahydroxy organic acid obtainable by oxidation of an aldohexose is subjected to at least one of alkali refining, bleaching, and deodorizing.

[0036] In another embodiment, the oil obtained by contacting renewable resource derived oil with at least one tetrahydroxy organic acid obtainable by oxidation of an aldohexose is subjected to at least one of bleaching and physical refining.

[0037] In an alternative embodiment the oil subjected to at least one of alkali refining, bleaching, and deodorizing oil obtained after contacting renewable resource derived oil with at least one tetrahydroxy organic acid obtainable by oxidation of an aldohexose further comprises an anisidine value of no greater than 1.

[0038] In an embodiment, a composition comprising alkali refined, bleached, deodorized oil obtainable by degumming crude renewable source derived oil with at least one of an aldaric acid, a uronic acid, an aldonic acid, or a combination of any thereof, wherein the ratio of the anisidine value of the refined, bleached deodorized oil to the anisidine value of the crude oil (Ratio pAV RBD/pAV crude) is not greater than 1.2 is disclosed. In an embodiment thereof, the aldaric acid comprises glucaric acid

[0039] The present invention is further demonstrated by the examples that follow.

COMPARATIVE EXAMPLE 1

[0040] Crude soy oil was obtained from ADM (Decatur, IL) for all testing. Crude soy oil (175 grams) was heated to 85 degrees C, then a 75% phosphoric acid solution (700ppm) was added to degum the oil. The heated oil was subjected to shear mixing with an immersion blender at 10,000 RPM for 1 minute. The mixture was then vigorously agitated with an overhead impeller at 85 degrees C for 1 hour. The oil was cooled to 70 degrees C, then water (3.5 mL, 2 wt. percent) was added to hydrate the gums and mixing was continued another 30 minutes. The oil was centrifuged at 4,000 RPM for 10 minutes and degummed oil was decanted. Residual metals (Fe, Ca, Mg, and P) were measured in the degummed oil by ICP to determine the efficiency of the phosphoric acid degumming treatment. The level of each of the Ca, Mg and P in the degummed oil was reduced by phosphoric acid degumming. Phosphoric acid degumming effected removal of Fe, Ca, Mg, and P at 96%, 93%, 92% and 89%, respectively

COMPARATIVE EXAMPLE 2

[0041] Crude soybean oil from Example 1 was water degummed substantially as outlined in Example 1 using water (700 ppm). Water degumming effected removal of Fe, Ca, Mg, and P at 62% 70%, 45%, and 87%, respectively.

COMPARATIVE EXAMPLE 3

[0042] Crude soybean oil from Example 1 was degummed substantially as outlined in Example 1 using 700ppm citric acid (50% solution). Crude soybean oil from Comparative Example 1 was degummed substantially as outlined in Comparative Example 1. Citric acid degumming effected removal of Fe, Ca, Mg, and P at 98%, 94%, 94% and 94%, respectively.

COMPARATIVE EXAMPLE 4

[0043] Crude soybean oil from Example 1 was degummed substantially as outlined in Example 1 using 700ppm tartaric acid (50% solution). Tartaric acid degumming effected removal of Fe, Ca, Mg, and P to below detection limits (at least 99% removal).

COMPARATIVE EXAMPLE 5

[0044] Crude soybean oil from example 1 was degummed with phosphoric acid substantially as outlined in Example 1, then subjected to refining, bleaching, and deodorizing to obtain refined, bleached, deodorized soybean oil. Crude soybean oil (600g) was degummed with 700 PM 75% cone. Phosphoric acid substantially as outlined in Example 1.

[0045] The degummed oil was decanted from the gums for further refining. The dosage of sodium hydroxide required for alkali refining was determined based on the content of free fatty acids (FFA) in the oil. The degummed oil was heated to 70 degrees C and 10 ml of a 10% solution of sodium hydroxide was added to the oil, followed by mixing at 70 degrees C for 15 minutes. The oil was then centrifuged to separate a heavy soapstock phase from an oil phase. The oil was decanted and the oil was washed with 100 ml hot water by mixing at 70 degrees C for 15 minutes. The oil was centrifuged to separate the oil and water phases. The oil was decanted and dried under vacuum at 90 degrees C for 15 minutes to yield once-refined (OR) oil. The alkali-refined oil (300g) was bleached by contacting withl .2 grams of F72FF clay from BASF (Ludwigshafen, Germany), (0.4% dosage) under vacuum (5 torr, 667 Pa) at 110 degrees C for 20 minutes. The oil was filtered to remove the spent bleaching clay to obtain refined, bleached (RB) oil. The refined, bleached oil was deodorized at under vacuum (1 torr, 133 Pa) 240 degrees C for 30 minutes to yield phosphoric acid degummed, refined, bleached, deodorized (RBD) oil. The oil was analyzed after each refining step (data shown below in Example 5).

EXAMPLE 1

[0046] Crude soy oil of good quality was obtained from ADM (Decatur, IL). Powdered D-glucaro 1, 4-6:3 dilactone was obtained from Chemica Inc. (Los Angeles, Ca). The dilactone was added to water, which dissociated to make a 50% glucaric acid solution. Crude soy oil (175 grams) was heated to 85 degrees C, then 700ppm glucaric acid was added to degum the oil. The heated oil was subjected to shear mixing with an immersion blender at 10,000 RPM for 1 minute. The mixture was then vigorously agitated with an overhead impeller at 85 degrees C for 1 hour. The oil was cooled to 70 degrees C, then water (3.5 mL, 2 wt. percent) was added and mixing was continued another 30 minutes. The oil was centrifuged at 4,000 RPM for 10 minutes and degummed oil was decanted. Residual metals (Fe, Ca, Mg, and P) were measured in the degummed oil by ICP to determine the efficiency of the degumming treatment. The level of each of the Ca, Mg and P in the degummed oil was reduced by glucaric acid degumming. Glucaric acid removed 97% each of the Ca, Mg, and P from the crude oil. Fe was undetectable in the degummed oil (0.02ppm detection limit).

EXAMPLE 2

[0047] A solution of gluconic acid (50%) was obtained from PMP Fermentation Products Inc. Crude soybean oil from Example 1 was degummed with a 50% solution of gluconic acid substantially as outlined in Comparative Example 1; the dose of gluconic acid in the oil was 700 ppm. Gluconic acid degumming effected removal of Fe, Ca, Mg, and P at 98%, 95%, 97% and 95%, respectively. EXAMPLE 3

[0048] Solutions of 50% glucaric acid from Example 1 and 50% gluconic acid from Example 2 were combined in various amounts (Table 3). Crude soybean oil from Example 1 was degummed substantially as outlined in Comparative Example 1 using the combined solution (700ppm in oil). Degumming with the combinations of glucaric and gluconic effected removal of Fe, Ca, Mg, and P (Table 3).

Table 3. Levels of metals remaining in degummed oil after degumming with 700 ppm blends of glucaric and gluconic acids (each in 50% solution). Metals are reported in mg/kg oil.

EXAMPLE 4

[0049] A tetrahydroxy carboxylic acid (glucaric acid) mixture was obtained from Rennovia, Inc. (Santa Clara, CA). The mixture was prepared by the oxidation of a solution of an aldohexose (glucose) over a proprietary catalyst, followed by partial purification by simulated moving bed chromatography. The resulting glucaric acid-rich solution contained nominally about 40% glucaric acid (an aldaric acid) and about 1.75% gluconic acid as measured by ion chromatography using conductivity detection. The crude soybean oil of Comparative Example 1 was degummed out substantially as outlined in Comparative Example 5 using a solution of the glucaric acid-rich solution (700 ppm acid). Degumming with the glucaric acid-rich solution effected removal of Fe, Ca, Mg, and P at 85%, 82%, 85% and 88%, respectively. EXAMPLE 5

[0050] Crude soybean oil from Example 1 was degummed substantially as outlined in Comparative Example 1 using the 50% glucaric acid solution from Example 1. The glucaric acid degummed oil was subjected to refining, bleaching, and deodorizing as outlined in Comparative Example 5 to yield glucaric acid degummed, refined, bleached, deodorized (RBD) oil. The characteristics of the oils after degumming and refining, bleaching, and deodorizing are shown in Table 4.

Table 4. Characteristics of crude soybean oil degummed with phosphoric or glucaric acid, and refined, bleached, deodorized (RBD) oil from oil degummed with phosphoric or glucaric acid. Lovibond Color values were obtained with a 5.25" cell unless otherwise noted.

degummed oil and RBD oil from phosphoric acid degumming were equivalent.

Surprisingly, degumming with glucaric acid allowed the production of RBD oil with an

Anisidine Value of less than 1. The lower Anisidine Value of the RBD oil obtained from glucaric acid degummed oil (0.9) represents a significant improvement over the Anisidine

Value of RBD oil obtained from phosphoric acid degumming (2.6). When degummed with phosphoric acid, the ratio of the anisidine value of the refined, bleached deodorized oil (2.6) to the anisidine value of the crude oil (0.9) (Ratio pAV RBD/pAV crude) was 2.89, which is significantly greater than 1.2 similar to the literature ratio of 4.5 disclosed in J. Amer. Oil Chem. Soc. 51(2) 17-21, 1974.

[0052] Significantly, the corresponding ratio of the anisidine value of the refined, bleached deodorized oil to the anisidine value of the crude oil (Ratio pAV RBD/pAV crude) when degummed with glucaric acid was well below 1.2 (1.00).

EXAMPLE 6

[0053] Crude soybean oil of poor quality (high metals, including extremely high phosphorus) was degummed substantially as outlined in Comparative Example 1 using the 50% glucaric acid solution from Example 1. The glucaric acid degummed oil was refined, bleached, and deodorized substantially as outlined in Comparative Example 5 to yield glucaric acid degummed, refined, bleached, deodorized (RBD) oil from poor quality oil. As a control, the same oil was subjected to degumming with citric acid substantially as outlined in comparative example 3 and refined, bleached, and deodorized (Table 5).

Table 5. Characteristics of crude soybean oil of poor quality degummed with citric or glucaric acid, and refined, bleached, deodorized (RBD) oil from oil degummed with citric or glucaric acid.

[0054] When this poor quality crude soybean oil was subjected to degumming with citric acid and refined, bleached, and deodorized, RBD oil with an anisidine value of 3.3 was obtained. When the same oil was refined using the glucaric acid-rich solution, refined, bleached, deodorized oil having an anisidine value of 2.7 was obtained.

[0055] The lower Anisidine Value of the RBD oil obtained from glucaric acid degummed oil (2.7) represents a significant improvement over the Anisidine Value of RBD oil obtained from citric acid degumming (3.3). Thus, when degummed with citric acid the ratio of the anisidine value of the refined, bleached deodorized oil to the anisidine value of the crude oil (Ratio pAV RBD/pAV crude) was greater than 1.2 (1.32). Significantly, when degummed with glucaric acid-rich solution the ratio of the anisidine value of the refined, bleached deodorized oil to the anisidine value of the crude oil (Ratio pAV RBD/pAV crude) was well below 1.2 (1.08).

Claims

1. A method for degumming renewable source derived oils comprising contacting the oil with a tetrahydroxy carboxylic acid obtainable by oxidation of an aldohexose.

2. The method of claim 1, wherein the acid comprises at least one of an aldaric acid or a uronic acid.

3. The method of claim 2, wherein the aldaric acid comprises at least one of glucaric acid, saccharic acid, galactaric acid, mucic acid, mannaric acid, allaric acid, altraric acid, idaric acid, gularic acid, or talari c acid.

4. The method of claim 2, wherein the uronic acid comprises at least one of glucuronic acid, galacturonic acid, mannuronic acid, alluronic acid, altruronic acid, iduronic acid, guluronic acid, or taluronic acid.

5. The method of claim 1, wherein the aldohexose is selected from the group consisting of glucose, galactose, mannose, allose, altrose, idose, gulose, talose, and combinations of any thereof.

6. The method of claim 1, wherein the renewable source derived oil comprises at least one of animal oil, algal oil, microbial oil, plant oil, or vegetable oil.

7. The method of claim 1, wherein the renewable source derived oil is crude renewable source derived oil.

8. The method of claim 2, wherein the aldaric acid comprises glucaric acid and lactones thereof.

9. The method of claim 2, wherein the aldonic acid comprises gluconic acid and lactones thereof.

10. The method of claim 1, further comprising subjecting the degummed oil to at least one of alkali refining, bleaching, and deodorizing.

11. The method of claim 1, further comprising subjecting the degummed oil to at least one of bleaching and physical refining.

12. The method of claim 10, wherein the alkali refined, bleached, deodorized oil further comprises an anisidine value of no greater than 1.

13. A composition comprising alkali refined, bleached, deodorized oil obtainable by degumming crude renewable source derived oil with at least one of an aldaric acid or a uronic acid, wherein the ratio of the anisidine value of the refined, bleached deodorized oil to the anisidine value of the crude oil (Ratio pAV RBD/pAV crude) is not greater than 1.2.

14. The composition of claim 13, wherein the aldaric acid comprises glucaric acid.