MXPA97008887A - Treatment of cooking oils and greases with magnesium silicate and alcali materials - Google Patents

Abstract

A process for treating cooking oil or fats comprising contacting the cooking oil or fat with magnesium silicate and at least one alkaline material such as, for example, calcium hydroxide. The magnesium silicate and at least one alkaline material are present in effective amounts to reduce the content of the free acids in the oil or fat and allow the reuse of cooking oil or fat. This method provides improved prolongation of the cooking oil duration used in restaurant and industrial frying operation.

Description

"TREATMENT OF COOKING OILS AND GREASES WITH MAGNESIUM SILICATE AND ALKALINE MATERIALS" This application is a continuation in part of the Application Serial Number 08 / 462,510, filed on June 5, 1995, the content of which is incorporated herein by reference. This invention relates to the treatment of cooking oils and fats. More particularly, this invention relates to the treatment of cooking oils and fats that reduce the free fatty acid content thereof by contacting the cooking oils and fats with magnesium silicate and alkaline materials, such as calcium hydroxide or sodium bicarbonate. Cooking oils and fats are generally used for cooking or frying foods, such as chicken, fish, potatoes, potato slices, legumes and cakes. This frying can be done in a restaurant where the food is prepared for immediate consumption, or in an industrial frying operation where the food is prepared in mass quantities for packing, shipping, future consumption. In a typical restaurant frying operation, large quantities of edible cooking oils or fats are heated in troughs at temperatures from about 157 ° C to about 204 ° C or more, and the food is immersed in cooking oil or fat. . During repeated use of cooking oil or fat, high cooking temperatures, in combination with the water in the frying food, causes the formation of free fatty acids (or FFA). An increase in FFA decreases the temperature of the oil smoke and results in an increase in smoke as the oil ages. Industrial frying operations involve frying large quantities of food for delayed consumption. Frequently this is a continuous operation with the food being carried through the hot oil through a conveyor. Industrialists frying meat and poultry should follow the guidelines of the "FDA Foof Safety and Inspection Service (FSIS) Meat and Poultry Inspection Manual". The following are excerpts from the manual: Section 18.40 Meat Fry The length of time that fats and oils can be used for deep frying varies with temperature, quality of the new fat added daily and fat treatment during use. The stability of these greases for additional use can be determined by the degree of foaming during use or the color, odor and taste. Grease or oil should be discarded when it foams across one side of the container during cooking, and when its color becomes almost black, as seen through a clear glass container. Section 18.40 Acceptability of Frying Fat (b) of Poultry (5) Used grease can be made satisfactory by filtering by adding new grease and cleaning the equipment regularly. Large amounts of sediment and free fatty acid content in excess of 2 percent are usual indications that frying fats are harmful and require reconditioning or replenishment. The majority of industrialists who use the 2 percent free fatty acid limit (FFA), or less if your customers require it for poultry as your main specification for the quality of the oil regardless of the food you are frying. In addition to the hydrolysis that forms the free fatty acids, the oxidative degeneration of fats occurs as a result of the contact of the air with the hot oil, thus producing oxidized fatty acids (or OFA). Heating transforms oxidized fatty acids into secondary and tertiary byproducts that can cause unpleasant tastes and unpleasant odors in the oil and fried food. Caramelization also occurs during the use of the oil over a certain period of time, resulting in a very dark color of the oil that, combined with the other by-products, produces dark and unattractive fried foods. Due to the cost resulting from the replenishment of cooking oils and fats after the use thereof, food industries have sought effective and economical ways to slow down the degradation of fats and oils in order to extend their usable life. U.S. Patent No. 4,112,129 issued to Duensing et al. Discloses a composition consisting of diatomite, synthetic calcium silicate hydrate, and synthetic magnesium silicate hydrate that can be used to restore used fats and oils. U.S. Patent No. 4,681,768 issued to Mulflur et al. Discloses a process for treating the cooking oil or grease used by contacting the used cooking oil or grease with an amorphous synthetic magnesium silicate of high surface area having a surface area of at least 300 square meters per gram. Most industrialists who use Silasorb (Celite Corporation of Denver, Colorado), which is a synthetic calcium silicate, as their filter medium because it is very effective in decreasing the concentration of free fatty acid. Silasorb decreases the concentration of free fatty acid (FFA) in the oil by a combination of adsorption and neutralization. The use of Silasorb, however, often obscures the oil. In addition, the neutralization product of a fatty acid with an alkali metal is a fatty acid soap. The amount of soap formed depends on the amount of alkali metal present and the initial percentage of free fatty acids in the oil. When the soap level is high, the oil foams. The use of Silasorb in order to decrease the concentration of the free fatty acid, sometimes results in uncontrollable foaming. Therefore, an object of the present invention is to provide an improved process for removing free fatty acids from cooking oil or fat used in frying operations in restaurants or industrial frying operations.

In accordance with one aspect of the present invention there is provided a process for treating the cooking oil or fat. The process comprises contacting cooking oil or fat with magnesium silicate and at least one alkaline material which is selected from the group consisting of alkaline earth metal hydroxides; alkaline earth metal oxides; alkali metal carbonates; alkali metal bicarbonates; alkaline earth metal carbonates and alkali metal silicates. The magnesium silicate and at least one alkaline material are present in effective amounts to reduce the content of the free fatty acids in cooking oil or fat, and extend the usable life of cooking oil or fat. The magnesium silicate and at least one alkaline material are preferably used in a composition or mixture; however, the materials can be added separately. In a preferred embodiment, the ratio of magnesium silicate to alkaline material used to treat the oil or fat is generally at least 1.8: 1, preferably at least 9: 1, and does not generally exceed 32: 1 and in most cases does not exceed 19: 1, all in weight. Therefore, in a composition in a preferred embodiment based on the two components, the magnesium silicate is present in the composition in an amount of about 65 weight percent to about 97 percent, preferably about 90 percent by weight. weight at about 95 weight percent. Generally, magnesium silicate is a magnesium silicate that is acceptable as a filter aid in food processing applications. For example, the "Food Chemical Codex", Third Edition, provides the following specifications for a synthetic magnesium silicate that is acceptable in food processing and industrial frying operations: Loss during ignition 15% max (dry basis) Percentage of MgO 15% min (based on ignition) Percentage of SIO2 67% min (based on lit) Soluble salts 3% max Molar ratio of MgO: Si? 2 1: 1.36 to 1: 3.82 In one embodiment, the magnesium silicate is an amorphous synthetic magnesium silicate having a surface area of at least 300 square meters per gram and preferably has a surface area of about 400 square meters per gram up to about 700 square meters per gram. and especially preferably has a surface area of about 400 square meters per gram to about 600 square meters per gram. In addition, this magnesium silicate preferably employs as coarse particles, with at least 75 percent and preferably at least 85 percent of the particles having a particle size that is greater than 400 mesh, and without further 15 percent and preferably not more than 5 percent all by weight, which has a particle size greater than 40 mesh. In most cases, the average particle size of the magnesium silicate used in accordance with this invention is within order, but not limited to 20 to 75 microns. It should be understood, however, that the magnesium silicate can have a particle size different from the size described above. For example, the magnesium silicate can be used as a finely divided powder, that is, 50 percent or more passes through a 325 mesh screen. In addition, the hydrated magnesium silicate that is used in accordance with a preferred embodiment of the present invention, generally has a bulk density in the order of 240 to 560 grams per cubic centimeter, a pH of 7 to 10.8 (5 percent suspension in water) and a molar ratio of MgO to SIO2 of 1: 1.8 to 1 :4. The following is a specification and typical value for a magnesium silicate that is employed in accordance with a preferred embodiment of the present invention. PICTURE Parameter Specification Typical Value Loss during ignition at 900 ° C 15% max 12% Molar ratio of MgO: Si02 1: 2.75 to 1: 2.75 1: 2.60 pH of suspension in water at 5% 9.5 ± 0.5 9.6 Soluble salts,% by weight 3.0 max 1.0 % Sieve Analysis: Surface area (BET) 300 ^ / gr min 400 A representative example of this synthetic magnesium silicate having a surface area of at least 300 square meters per gram can be obtained as Magnesol® Poly 30/40, a product of the Dallas Group of America, Inc. Liberty Corner, N.J. and also described in U.S. Patent No. 4,681,768. In another embodiment, the magnesium silicate is an aqueous amorphous synthetic precipitated magnesium silicate that has been treated to reduce the pH thereof to less than about 9.0. As used herein, the term "precipitate" means that the amorphous hydrated synthetic precipitated magnesium silicate is produced as a result of the precipitation formed during contact of a magnesium salt and a silicate source in an aqueous medium. For purposes of the present invention, the pH of the magnesium silicate is the pH of the magnesium silicate as measured in a 5 percent thick slurry of magnesium silicate in water. The pH of the magnesium silicate treated in a 5 percent thick slurry is preferably from about 8.2 to about 8.9, and especially preferably from about 8.5 to about 8.8. Examples of this treated amorphous aqueous precipitated synthetic magnesium silicate can be obtained as the Magnesol® XL and Haze-Out ™ products from Dallas Group of America, Inc. Liberty Corner, N.J. and also as described in U.S. Patent No. 5,006,356. These products have an average particle size of approximately 70 microns and 30 microns, respectively. In still another embodiment, the magnesium silicate is a magnesium silicate having a surface area of about 50 square meters per gram up to about 150 square meters per gram. Preferably, this magnesium silicate has a molar ratio of MgO to SIO2 from about 1: 2.6 to about 1: 3.4 and a pH (5 percent water suspension) of about 9.5 to about 10.5. An example of this magnesium silicate can be obtained as Magnesol® HMR-LS, a product of Dallas Group of America, Inc. of Liberty Corner, N.J. In another embodiment, the magnesium silicate can be in the talc form. It will be understood, however, that the scope of the present invention is not limited to any specific type of magnesium silicate or method for the production thereof. In one embodiment, at least one alkaline material is an alkaline earth metal hydroxide. Preferably, the alkaline earth metal hydroxide is calcium hydroxide (Ca (OH) 2). In another embodiment, at least one alkaline material is an alkaline earth metal oxide. The alkaline earth metal oxides that are employed include, but are not limited to, magnesium oxide (MgO) and calcium oxide (CaO). In another embodiment, at least one alkaline material is an alkali metal carbonate. The alkali metal carbonates that may be employed include but are not limited to sodium carbonate (Na 2 C 3). In another embodiment, at least one alkaline material is an alkali metal bicarbonate. Alkali metal bicarbonates that may be employed include but are not limited to sodium bicarbonate (NaHC 3) and potassium bicarbonate (KHCO 3). In a preferred embodiment, the alkali metal bicarbonate is sodium bicarbonate (NaHCO 3). In another embodiment, at least one alkaline material is an alkaline earth metal carbonate. The alkaline earth metal carbonates that may be employed include, but are not limited to, calcium carbonate (CaCO3). In another embodiment, at least one alkaline material is an alkali metal silicate. The alkali metal silicates that may be employed include, but are not limited to sodium metasilicate (Na2Si? 3). In another embodiment, at least one alkaline material is present in an amount of 3 weight percent to about 35 weight percent, preferably from about 5 weight percent to about 10 weight percent, the rest being silicate of magnesium based on the two components. The magnesium silicate and at least one alkaline material used in accordance with the present invention can be used to treat the oil and / or cooking fats together with any operation for filtering the oil and cooking fats used. The method of the present invention is applicable to continuous filtration systems where the cooking oil used is circulated continuously through filtration units and back to the tundish and / or trough systems where one or more times a day the content of each frying pan is filtered - through a filter of intermittent type. The magnesium silicate and at least one alkaline material used in accordance with the present invention can be used both as a precoat and as a body feed in either a continuous or intermittent filtration system. In a conventional cooking appliance, or in an industrial frying application generally at least .00227 kilogram of the composition and preferably at least .0045 kilogram of the composition is employed per kilogram of the cooking oil used. In general, the amount of the composition used does not exceed .00908 kilogram per .454 kilogram of cooking oil used. The selection of an optimal quantity will depend but will not be limited to the frequency of treatment and oil conditions. Magnesium silicate and at least one alkaline material are used in an amount effective to reduce FFA or color or other contaminant levels to extend the period of oil use. The maximum amount will be determined by the amount of oil required, reasons for economy, flow properties by filtration in the operation. In general, the treatment is carried out in such a way that the cooking oil or fat does not cool down to a temperature below 71 ° C. In one embodiment, after treatment with the magnesium silicate and at least one alkaline material, the treated oil can be combined with a conventional filter aid for subsequent filtration. It should be understood, however, that in most cases the magnesium silicate and at least one alkaline material can be used to treat the cooking oil used and after this treatment the oil is filtered without the addition of an auxiliary of conventional filter.

The magnesium silicate and at least one alkaline material used in accordance with the present invention are capable of maintaining contaminant levels less than the point of being discarded for a prolonged period of time. This is accomplished without producing any other damaging effects on the oil, such as excessive discoloration or excessive foaming. The present invention is also applicable to industrial frying operations that are carried out as described above. Applicants have found that, by contacting the cooking oil used in conventional restaurant type filtering and frying systems or in industrial frying systems, with a combination of magnesium silicate and at least one alkaline material, a Improved prolongation of the useful life of the cooking oil without detrimentally affecting the quality of the food. This treatment reduces the free fatty acid content of the oil without causing excessive discoloration or foaming. The quality of the food has actually been known to improve with use. The invention will now be described with respect to the drawings, wherein: Figure 1 is a graph of the free fatty oil content through the course of time of (i) an untreated cooking oil; (ii) a cooking oil treated with magnesium silicate and calcium hydroxide; (iií) a cooking oil treated with magnesium silicate; and (iv) a cooking oil treated with calcium silicate; Figure 2 is a graph of the photometric color through the time course of the cooking oils described in Figure 1; and Figure 3 is a graph of the titratable soap value (parts per million) through the time course of the cooking oils described in Figure 1. The invention will now be described with respect to the following examples; however, the scope of the present invention is not intended to be limited thereto. In the following examples, the initial and treated oils were analyzed using the official methods of American Oil Chemists' Society for the percentage of free fatty acids (Ca 5a-40), the photometric color (Ce 13c-50), the value of the soap valorable (Ce 17-79) to determine these values and the changes in these values as a result of the treatments that will be described below.

Also, in the following examples PC-80 is a synthetic, aqueous, amorphous precipitated magnesium silicate, which has been treated to reduce the pH thereof to less than about 9.0, the magnesium silicate having an average particle size of 20. micrometers Example 1 In a set of experiments, a used cooking oil having a free fatty acid (FFA) content of 1. 10 percent was treated at a temperature of 150 ° C for one hour with the following mixtures of Magnesol® XL and alkaline materials: 1. 65 weight percent Magnesol® XL and 35 weight percent MgO. 2. 65 weight percent Magnesol® XL and 35 weight percent a2C? 3. 3. 65 weight percent Magnesol® XL and 35 weight percent NaHCO3. The aforementioned mixtures are referred to as Mixture 1, Mixture 2 and Mixture 3. Magnesol® XL was present in an amount of 1 weight percent based on the weight of the oil. The MgO, Na 2 C 3 or NaHCO 3 was present in an amount of 0.60 gram.

In another set of experiments, the oil was contacted at a temperature of 150 ° C for one hour with 2 weight percent, based on the weight of the oil, of the following treatment mixtures; which are also referred to as Mixtures 4 through 15: 4. Silasorb alone. 5. 95 weight percent Magnesol® XL and 5 weight percent NaHCO3. 6. 95 weight percent Magnesol® XL and 5 weight percent aHC03. 7. 90 weight percent Magnesol® XL and 10 weight percent NaHCO3. 8. 85 weight percent Magnesol® XL and 15 weight percent aHC03. 9. 85 weight percent Magnesol® XL and 15 weight percent NaHCO3- 10. 75 weight percent Magnesol® XL and 25 weight percent aHC03. 11. 65 weight percent Magnesol® XL and 35 weight percent NaHCO3. 12. 95 weight percent Magnesol® XL and 5 weight percent KHCO3. 13. 90 weight percent Magnesol® XL and 10 weight percent KHCO3. 14. 85 weight percent Magnesol® XL and 15 weight percent KHCO3. 15. 75 weight percent Magnesol® XL and 25 weight percent KHCO3. Silasorb is a calcium silicate that has the following typical chemical analysis: SYSO2 - 46.68 percent by weight. CaO - 28.12 weight percent. AI2O3 - 2.0 weight percent. Fe2? 3 - 1.0 weight percent. MgO - 0.6 percent by weight. Na2? + K2? = 1.4 percent by weight. Total loss during ignition - 15.0 percent by weight. Changes in the percentage of FFA and the value of the soap became known as the real change in value. The change in color is disclosed as a percentage of the initial value. A negative sign indicates that the value increased. The results are given in Table I, which is presented below.

Table I Mix% Change% change Change FFA value of soap color FFA (ppm) Initial oil 1.10 0. 95 0.15 14.3 0. 93 0.17 14.3 -50 0. 20 0.90 -2.3 -645 4 0.74 0.36 -10.5 -510 0.79 0.31 21.3 -145 6 0.77 0.33 8.3 -326 7 0.69 0.41 2.5 -1750 8 0.43 0.67 2.3 -401 9 0.37 0.73 -18.9 -830 10 0.15 0.95 -5.1 -285 11 0.20 0.90 -2.3 • 645 12 0.84 0.26 5.9 -123 13 0.79 0.31 4.1 -324 14 0.77 0.33 -0.7 -577 0.44 0.66 -146 -2680 Example 2 In a set of experiments, a cooking oil having an initial FFA content of 1.15 percent was treated at a temperature of 150 ° C for one hour with 2 weight percent based on the weight of the oil, of Silasorb alone (Mixture 4) or one of the following absorbers, which will be referred to below as Mixture 16 and Mixture 17: 16. 90 weight percent PC-80 and 10 weight percent CaO. 17. 90 percent by weight of PC-80 and 10 percent by weight of Ca (OH) 2- In another experiment, a used cooking oil having a free fatty acid content of 1.04 percent by weight was treated as described in the foregoing with 2 weight percent Silasorb alone (Mix 4) or one of the following absorbents, to which reference will be made below as mixtures 18 to 21. 18. 95 weight percent PC-80 and 5 weight percent Ca (OH) 2-19. 93 weight percent PC-80 and 7 percent Ca (OH) 2- 20. 90 percent by weight of PC-80 and 10 percent of Ca (OH) 2- 21. 90 percent by weight of PC-80 and 10 percent by CaO. Free fatty acid values, changes in free fatty acid content, color changes and changes in soap value were determined as will be described below. The results are given in Table II, which is presented below.

Table II Mix% Change% change Change FFA value of FFA color soap (ppm) Oil 1. 15 initial 0. 78 0.37 -10.6 -316 16 0.83 0.32 8.5 -82 17 0.68 0.47 13.9 -167 Initial oil 1.04 0. 83 0.21 0 -150 18 0.80 0.24 19.9 -65 19 0.70 0.34 11.4 -416 0.69 0.35 21.3 -78 21 0.81 0.23 16.1 -92 The aforementioned results show that calcium hydroxide has a more positive effect than calcium oxide in decreasing the concentration of FFA, and in improving oil color.

Example 3 In this example, four sets of 18,260 kilograms of chicken were fried per day in partially hydrogenated soybean oil in a frying pan of capacity 4.54 kilograms. The oils were treated daily for one hour with 2 weight percent based on the weight of the oil of (i) Magnesol® 30/40; (ii) 95 weight percent PC-80 and 5 weight percent Ca (OH) 2; or (iii) Silasorb. A fourth oil was not treated (Control). The oils were treated before filtration. The tests for the control oil, the oil treated with Magnesol® 30/40 and the oil treated with 95 percent by weight of PC-80 and 5 percent of Ca (OH) 2 were terminated when the FFA content of the oil was more than percent by weight. The Silasorb oil test ended when the oil began to foam uncontrollably. The untreated control oil was used for 5 days. The oil treated with PC-80 and Ca (OH) 2 was used for 14 days. The oil treated with Magnesol® 30/40 was used for 11 days. The oil treated with Silasorb was used for 10 days. The oils were tested to determine the percentage content of FFA, the photometric color, and the value of the titratable soap (ppm). The results of the percentage content of FFA are shown in Figure 1; the results of the photometric color are shown in the Figure 2; and titratable soap values are shown in Figure 3. The results indicate that the mixture of 95 weight percent PC-80 and 5 weight percent Ca (OH) 2 was superior to the other systems tested in all the respects of the quality of oil: days of frying; percentage of FFA content, photometric color and titratable soap value.

Example 4 The cooking oil obtained from a potato slicer frying pan having an initial free fatty acid content of 0.55 percent and a color reading of 10.1 was contacted with (i) a 95 percent absorbent composition in PC-80 weight and 5 weight percent calcium hydroxide or (ii) an absorbent composition of 90 weight percent PC-80 and 10 weight percent sodium bicarbonate. The absorbents were added to oil samples in an amount of 0.71 weight percent of the oil, and remained in contact with the oil for 1 hour at 150 ° C. At the end of one hour, the percentage of free fatty acids, the amount of free fatty acids absorbed (milligrams per gram of the absorber), the photometric color and the percentage of color change were measured. The results are given in Table III presented below.

Table III Material% FFA Color% change FFA Adsorbed color Control (without adsorbent) 0.55 10.1 95% PC-80/5% Ca (OH) 2 0.50 70 7.0 30.7 90% PC-80/10% NaHC03 0.39 225 8.4 16.8 Example 5 The cooking oil obtained from a nut toaster having an initial free fatty acid content of 0.45 percent and a color reading of 58.2 was contacted with (i) an absorbent composition having 95 weight percent PC -80 and 5 weight percent calcium hydroxide or (ii) an absorbent having 90 weight percent PC-80 and 10 weight percent sodium bicarbonate. The absorbents were added to the oil samples in an amount of 2.0 weight percent of the oil and remained in contact with the oil for 1 hour at 150 ° C. At the end of one hour, the percentage of free fatty acids, the amount of free fatty acids adsorbed (milligram per gram of adsorbent), the photometric color and the percentage of color change were measured. The results are given in Table IV below.

Table IV Material% FFA Color% change FFA Adsorbed color Control (without absorber) 0.46 58.2 95% PC-80/5% Ca (0H) 2 0.26 100 34.3 41.1 90% PC-80/10% NaHC03 0.24 110 31.7 45.5 EXAMPLE 6 The cooking oil obtained from a frying pan for chicken pancakes having an initial content of free fatty acid of 1.93 percent and a color reading of 32.6 was contacted with (i) an absorbent composition having 95 weight percent PC-80 and 5 weight percent calcium hydroxide or (ii) an absorbent composition having 90 weight percent PC-80 and 10 weight percent sodium bicarbonate. The absorbents were added to the oil samples in an amount of 2.0 weight percent of the oil and remained in contact with the oil for 1 hour at 150 ° C. At the end of one hour, the percentage of free fatty acids, the amount of free fatty acids adsorbed (milligram per gram of adsorbent), the photometric color and the percentage of color change were measured. The results are given in Table V below. Table V Material of FFA Color% change FFA Adsorbed color Control (without absorber) 1.93 32.6 95% PC-80/5% Ca (0H) 2 1.47 230 28.7 12.0 90% PC-80/10% NaHC0 1.46 235 27.5 15.6 Example 7 The cooking oil having an initial free fatty acid content of 1.41 percent and a color reading of 10.3 was contacted with (i) a magnesium silicate adsorptive power composition which is a synthetic precipitated aqueous magnesium silicate. amorphous having a pH in a 5 percent thick suspension of 8.2 (no turbidity); or (ii) an adsorbent composition having 95 percent by weight of PC-80 and 5 percent of calcium hydroxiod or (iii) a composition having 93 percent by weight of PC-80 and 7 percent by weight of sodium bicarbonate. The adsorbents were added to the oil samples in an amount of 2.0 weight percent of the oil and remained in contact with the oil for 1 hour at 100 ° C. At the end of one hour, the percentage of free fatty acids, the amount of free fatty acids adsorbed (milligram per gram of the adsorbent), the photometric color and the percentage of color change were measured. The results are provided in Table VI below.

Table VI Material% FFA Color% change FFA Adsorbed color Control (no adsorbent) 1.41 10.3 No turbidity 1.19 110 8.5 17.5 95% PC-80/5% Ca (OH) 2 1-16 125 8.6 16.5 93% PC -80 / 7% NaHC03 0.98 215 8.8 14.6 The present invention is particularly advantageous since the useful life of the cooking oil and / or the fat (lard) which has been used for frying foods at high temperature can be prolonged thereby reducing the total cost. The use of magnesium silicate and of at least one alkaline material in accordance with the present invention maintain FFA levels less than the waste threshold and filtration can be achieved at high flow rates and with low pressure decreases whereby Magnesium silicate and at least one alkaline material can be used in combination with commercial lard filters as well as industrial frying systems.

The afortioned advantages and other advantages should be evident to those skilled in the art of the present teachings. The disclosure of patents, publications, including published patent applications and dated basis entries referenced in this specification are specifically incorporated by reference in their entirety to the same extent as if each individual patent, publication and entry of database will be specifically and individually indicated as being incorporated by reference. Numerous modifications and variations of the present invention are possible in view of the afortioned teachings and therefore, within the scope of the appended claims, the invention may be practiced in a manner other than that particularly described.

Claims (17)

R E I V I N D I C A C I O N E S:

1. A process for treating cooking oil or fat comprising: contacting the cooking oil or fat with (a) magnesium silicate and (b) at least one alkaline material which is selected from the group consisting of alkaline earth metal hydroxides; alkaline earth metal oxides; alkali metal carbonates; alkali metal bicarbonates; alkaline earth metal carbonates; and alkali metal silicates. The magnesium silicate and at least one alkaline material are present in effective amounts to reduce the content of the free fatty acids in the oil or fat and extend the usable life of cooking oil or fat.

2. The process of claim 1, wherein the ratio of magnesium silicate to alkaline material is at least 1.8: 1 and not greater than 32: 1, all and by weight.

3. The process of claim 1, wherein the ratio of magnesium silicate or alkaline material is at least 9: 1 and not greater than 19: 1, all and by weight.

4. The process of claim 1, wherein the magnesium silicate has a surface area of at least 800 square meters per gram.

5. The process of claim 4, wherein the magnesium silicate has a surface area of at least 400 to about 700 square meters per gram.

The process of claim 4, wherein the magnesium silicate has a particle size such that at least 75 percent of the particles have a size greater than 400 mesh and no more than 15 percent have a 40 mesh larger particle size.

The process of claim 4, wherein the magnesium silicate has a particle size of about 20 microns to about 75 microns.

The process of claim 4, wherein the magnesium silicate has a bulk density of from about 400 to about 512 grams per cubic centimeter.

9. The process of claim 1, wherein the magnesium silicate in a synthetic amorphous aqueous precipitated magnesium silicate and the magnesium silicate have been treated to reduce the pH thereof to less than about 9.0.

The method of claim 9, wherein the magnesium silicate has a pH in a 5 percent slurry of from about 8.2 to about 8.9.

11. The method of claim 10, wherein the magnesium silicate has a pH in a slurry at 5 percent from about 8.5 to about 8.8.

The method of claim 1, wherein the magnesium silicate has a surface area of about 50 square meters per gram to about 150 square meters per gram.

The method of claim 12, wherein the magnesium silicate has a molar ratio of MgO to Sio2 from about 1: 2.6 to about 1: 3.4, and a pH in a 5 percent water suspension of about 9.5 to about 10.5.

The method of claim 1, wherein at least one alkaline material is an alkaline earth metal hydroxide.

15. The method of claim 14, wherein the alkaline earth metal hydroxide is calcium hydroxide.

16. The method of claim 1, wherein at least one alkaline material is an alkali metal bicarbonate.

17. The method of claim 16, wherein the alkali metal bicarbonate is sodium bicarbonate.