Method for producing refined oils and fats

Abstract

Provided is a method which is for producing refined oil and fat and by which oil and fat, in which the content of at least one among 3-MCPD and glycidol is sufficiently reduced, can be efficiently obtained. This production method comprises a decolorization step for holding oil and fat for a time of 10-90 minutes at an oil-and-fat temperature of 100-170ºC under reduced pressure.

Description

[Technical Field]

[0001] This invention relates to a method for producing refined oils and fats. [Background technology]

[0002] The manufacturing process for edible oils and fats, regardless of the origin of the oil, typically involves a degumming process to remove phospholipids, a deacidification process to remove free fatty acids, a decolorization process to remove pigments, and a deodorization process to remove odorous components. Through these manufacturing processes, edible oils and fats with fewer impurities, a lower acid value, reduced coloration, and reduced odor can be obtained.

[0003] When manufacturing edible oils such as salad oil, where it is necessary for oil crystals not to form even at low temperatures, or when using oils with a high wax content as raw materials, a dewaxing process may be added to the manufacturing process of edible oils.

[0004] Incidentally, recently, oils and fats refined by physical refining are being sold. Physical refining is a process that deoxidizes oils and fats without using alkali treatment by degumming and decolorizing crude oil, followed by deodorizing. Many imported edible oils and fats are refined by physical refining, and palm oil that has undergone physical refining is called RBD (Refined Bleached Deodorized) palm oil (RBD oil) among those skilled in the art.

[0005] While RBD oils that have undergone physical refining are inexpensive, they are not sufficiently refined. Therefore, in most cases, physical refining is used as the primary refining process, and the oils refined by physical refining are further refined in Japan using conventional methods.

[0006] In recent years, with advances in analytical techniques, it has become clear that not only RBD oils, but also oils that have undergone the above-mentioned secondary purification of RBD oils, and oils obtained through the conventional manufacturing process described above, contain 3-chloropropane-1,2-diol or its fatty acid esters (hereinafter, these may be collectively referred to as "3-MCPDs").

[0007] 3-MCPDs are thought to be produced unintentionally, particularly during the deodorization process of oils and fats, from components naturally present in oils and fats, and are believed to be generated from lipids and chloride ions in the oils and fats. When fatty acid esters of 3-chloropropane-1,2-diol are ingested through food, these fatty acid esters are hydrolyzed in the body to produce 3-chloropropane-1,2-diol, and there are concerns about adverse health effects (nephrotoxicity) caused by 3-chloropropane-1,2-diol. Therefore, various studies are underway to reduce the content of 3-MCPDs in oils and fats.

[0008] For example, deodorization at temperatures lower than those previously known (see Non-Patent Document 1) is being investigated. For instance, Patent Document 1 proposes a method for reducing 3-MCPDs in oils and fats by deodorizing them at low temperatures of 100 to 240°C.

[0009] Another approach being considered involves adding an adsorbent to oils that have become contaminated with 3-MCPDs due to being exposed to high temperatures during the manufacturing process of refined oils, particularly in the deodorization process. For example, Patent Document 2 proposes a method for reducing MCPDs in oils by contacting oils that have undergone decolorization and deodorization processes with silica gel and / or basic activated carbon.

[0010] Furthermore, Patent Document 3 proposes a method for producing oils and fats in which MCPDs are reduced, by contacting the oil or fat with one or more inorganic powders selected from the group consisting of boehmite and hydrotalcite under certain temperature conditions. In addition, Patent Document 4 proposes a method for reducing chloropropanediols or their fatty acid esters by performing an adsorbent treatment in which oils and fats are contacted with zeolite. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2011-074358 [Patent Document 2] International Publication No. 2011 / 040539 [Patent Document 3] Japanese Patent Publication No. 2015-067692 [Patent Document 4] Japanese Patent Publication No. 2020-105477 [Non-patent literature]

[0012] [Non-Patent Document 1] The Japan Oil Chemists' Society (ed.), Fundamentals and Applications of Fats and Lipids, First Edition, April 1, 2005, pp. 218-219. [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] Conventional methods for reducing the content of 3-MCPDs and glycidols have had the following problems:

[0014] For example, the method of adjusting the deodorization temperature as described in Patent Document 1 can deodorize fats and oils while suppressing the generation of 3-MCPDs. However, it is necessary to perform the deodorization treatment for a longer time than when performing under the conventionally known deodorization temperature conditions, and there is a problem that the production efficiency is poor. Further, in Patent Document 1, since the amounts of 3-MCPDs, glycidols, etc. are totaled and the total amount is calculated in terms of free 3-MCPD, it is not disclosed how much each of 3-MCPDs and glycidols is specifically reduced.

[0015] Also, in the method of treating using an adsorbent, in the methods described in Patent Document 2 and Patent Document 3, there is a problem that the content of 3-MCPDs in fats and oils may not be sufficiently reduced. In particular, the method described in Patent Document 3 uses an adsorbent that cannot be used in the production of foods, so there is a problem that it cannot be used in the production of edible fats and oils. In the method described in Patent Document 4, while 3-MCPDs in fats and oils can be sufficiently reduced, there is a problem that the process of treating with an adsorbent increases compared to the conventional fat and oil production process, and thus the process tends to become complicated.

[0016] Therefore, the problem to be solved by the present invention is to provide a method for producing refined fats and oils capable of efficiently obtaining fats and oils in which the content of one or more of 3-MCPDs and glycidols is sufficiently reduced.

Means for Solving the Problems

[0017] In view of the above problems, when the inventors of the present invention conducted intensive studies, in each stage of the production process of refined fats and oils, placing fats and oils at a high temperature has been avoided as increasing the content of 3-MCPDs. However, unexpectedly, it was found that by performing the decolorization step in the production process of refined fats and oils at a temperature higher than the conventionally known temperature, it is possible to significantly reduce the content of 3-MCPDs.

[0018] The present invention has been completed based on this finding, and provides the following method for producing refined fats and oils and the refined fats and oils obtained thereby. [1] A method for producing refined oil and fat in which one or more of 3 - monochloropropane - 1,2 - diols and glycidols are reduced, including a decolorization step of maintaining at an oil and fat temperature of 100°C or higher and 170°C or lower for 10 minutes or longer and 90 minutes or shorter under reduced pressure. [2] A method for producing refined oil and fat in which one or more of 3 - monochloropropane - 1,2 - diols and glycidols are reduced, including adding clay to oil and fat at 70°C or higher and lower than 100°C, heating under reduced pressure until it reaches 100°C or higher and 170°C or lower, and maintaining at an oil and fat temperature of 10 minutes or longer and 90 minutes or shorter under reduced pressure. [3] A method for producing refined oil and fat in which one or more of 3 - monochloropropane - 1,2 - diols and glycidols are reduced, including heating oil and fat under reduced pressure to 70°C or higher and lower than 100°C, then adding clay to the oil and fat at 70°C or higher and lower than 100°C, heating under reduced pressure until it reaches 100°C or higher and 170°C or lower, and maintaining at an oil and fat temperature of 10 minutes or longer and 90 minutes or shorter under reduced pressure. [4] The method for producing refined oil and fat according to any one of [1] to [3] above, wherein the acidity of the clay used in the decolorization step is 0.50 - 2.50 (KOH mg / g). However, the acidity of the clay is measured and calculated by the methods shown in the following (1) to (4). (1) Weigh 10.0 g of clay into an Erlenmeyer flask, add 100 mL of ion - exchanged water, shake, and then let it stand and mark the water level. (2) Boil this for 5 minutes, let it cool, add ion - exchanged water up to the mark, filter the whole amount to obtain a filtrate. (3) Take 40 mL of the obtained filtrate into another Erlenmeyer flask, add 60 mL of distilled water to obtain a 100 - mL sample solution. (4) Titrate the sample solution obtained in (3) with N / 40 potassium hydroxide solution using phenolphthalein as an indicator, and calculate the acidity by the following formula.

Number

[0019] According to the method for producing refined oils and fats of the present invention, it is possible to efficiently obtain refined oils and fats in which the content of one or more of 3-MCPDs and glycidols is sufficiently reduced. [Modes for carrying out the invention]

[0020] The present invention will be described in detail below with reference to its preferred embodiments. The present invention is not limited by the following description, and each component can be modified as appropriate without departing from the spirit of the invention.

[0021] [Method of producing refined oils and fats] The present invention relates to a method for producing refined oil and fat with reduced contents of 3-MCPDs and glycidols. The method for producing refined oil and fat of the present invention (hereinafter, also simply referred to as "the production method of the present invention") includes a decolorization step (hereinafter, also simply referred to as "the decolorization step of the present invention" or "the decolorization step") of holding at an oil and fat temperature of 100°C or higher and 170°C or lower for 10 minutes or longer and 90 minutes or shorter under reduced pressure.

[0022] -Vacuum condition in the decolorization step- In the production method of the present invention, the decolorization step is carried out under reduced pressure.

[0023] Under reduced pressure generally refers to a state where the system is lower than atmospheric pressure (1013 hPa). As the reduced pressure condition (degree of reduced pressure) in the decolorization step of the present invention, from the viewpoint of suppressing oxidation of oil and fat during production, it is preferably 2.0×10 ,

[0026] Pa or lower, more preferably 1.8×10 4 Pa or lower, still more preferably 1.6×10 4 Pa or lower, particularly preferably 1.5×10 4 Pa or lower, and the lower limit is not particularly limited, but is preferably 1.0×10 2 Pa or higher or 5.0×10 2 Pa or higher, more preferably 1.0×10 3 Pa or higher or 5.0×10 3 Pa or higher, still more preferably 7.0×10 3 Pa or higher or 1.0×10 4 Pa or higher.

[0024] As a method for obtaining the above reduced pressure state, for example, a method of evacuating the system using a vacuum pump can be mentioned.

[0025] -Oil and fat temperature in the decolorization step- The production method of the present invention is characterized in that the oil and fat temperature (decolorization temperature) in the decolorization step is set to 100°C or higher and 170°C or lower. By performing the decolorization step under this temperature condition, refined oil and fat with reduced 3-MCPDs and glycidols can be obtained.

[0026] As mentioned above, in each stage of the refined oil and fat manufacturing process, placing oils and fats at high temperatures has been avoided because it increases the content of 3-MCPDs. In contrast, the present invention is based on the discovery that the content of 3-MCPDs can be significantly reduced by performing the decolorization process in the production of refined oils and fats at a temperature higher than previously known (for example, YHHui (1996). "Bailey's industrial oil and fat products: Fifth Edition Volume 4 Edible Oil and Fat Products Processing Technology", p201 indicates a recommended temperature of 75-85°C). This finding is entirely unexpected based on conventional technological understanding.

[0027] The oil temperature in the decolorization process is preferably 125°C or higher, more preferably 130°C or higher, even more preferably 135°C or higher, or 140°C or higher, from the viewpoint of more efficiently reducing the content of 3-MCPDs and glycidols in the refined oil, and its upper limit is preferably 165°C or lower, more preferably 160°C or lower, and even more preferably 155°C or lower.

[0028] -Decolorization process time (decolorization time)- In the manufacturing method of the present invention, the decolorization step is carried out by holding the oil at the above-mentioned oil temperature for a period of 10 minutes to 90 minutes. By setting the decolorization step time (decolorization time) within the above range, refined oils with reduced levels of 3-MCPDs and glycidols can be obtained.

[0029] In the decolorization process of the present invention, the decolorization time is preferably 15 minutes or more, more preferably 20 minutes or more, and even more preferably 25 minutes or more, from the viewpoint of efficiently reducing the content of 3-MCPDs and glycidols, and the upper limit is preferably 75 minutes or less, more preferably 60 minutes or less, and even more preferably 45 minutes or less. The starting point for calculating the decolorization time is the time when the oil temperature (decolorization temperature) arbitrarily set within the above range is reached. Furthermore, it is preferable to heat while stirring during the decolorization process.

[0030] In the manufacturing method of the present invention, the decolorization step is preferably carried out in a state where the oil and white clay are in contact, such as by adding white clay to the oil and fat. As will be described in detail later, in the manufacturing method of the present invention, it is preferable to keep the oil and white clay in contact before the oil reaches the above decolorization temperature.

[0031] The following describes the clay that can be preferably used in the manufacturing method of the present invention.

[0032] -Shirato- Examples of clays that can be used in the manufacturing method of the present invention include naturally occurring acidic clay (montmorillonite-type clay) and activated clay obtained by acid-treating the acidic clay with an inorganic acid such as sulfuric acid or hydrochloric acid.

[0033] In particular, in the present invention, it is preferable to use activated clay having a porous structure with a large specific surface area due to acid treatment. Although it varies depending on the degree of acid treatment, the specific surface area of ​​the activated clay is 50 m². 2 / g~400m 2 It is preferable that the value be / g.

[0034] The acidity of the clay (KOH mg / g) is preferably 2.50 or less, more preferably 2.00 or less, and even more preferably 1.50 or less, from the viewpoint of efficiently reducing 3-MCPDs and glycidols, with a lower limit of preferably 0.50 or more, more preferably 0.55 or more, and even more preferably 0.60 or more, 0.70 or more, or 0.80 or more. Therefore, in one embodiment, the acidity of the clay used in the decolorization process is 0.50 to 2.50 (KOH mg / g).

[0035] In this invention, the acidity of the clay is measured and calculated by the following methods (1) to (4). (1) Measure 10.0 g of clay into an Erlenmeyer flask, add 100 mL of deionized water, shake, and then let stand to mark the water level. (2) Boil this for 5 minutes, let it cool, add deionized water up to the mark, filter the entire volume, and obtain the filtrate. (3) Transfer 40 mL of the obtained filtrate to another Erlenmeyer flask and add 60 mL of distilled water to obtain 100 mL of sample solution. (4) The sample solution obtained in (3) is titrated with N / 40 potassium hydroxide solution using phenolphthalein as an indicator, and the acidity is calculated using the following formula.

[0036]

number

[0037] Activated clay generally contains SiO2, Al2O3, Fe2O3, CaO, MgO, etc. as its chemical components, but the mass ratio of SiO2 to Al2O3 (SiO2 / Al2O3 ratio) is preferably in the range of 3 to 12, and more preferably in the range of 4 to 10. Furthermore, a composition containing 1% to 5% by mass of Fe2O3, 0% to 1.5% by mass of CaO, and 1% to 7% by mass of MgO is preferred.

[0038] Commercially available acid clay products include Mizuka Ace #20, Mizuka Ace #300, Mizuka Ace #400, and Mizulight (all manufactured by Mizusawa Chemical Industry Co., Ltd.), while commercially available activated clay products include Galleon Earth V2R, Galleon Earth V2, Galleon Earth NVZ, and Galleon Earth NV (all manufactured by Mizusawa Chemical Industry Co., Ltd.).

[0039] There are no particular restrictions on the shape of the clay; for example, it can take various forms such as powder, lump, beads, or pellets. From the viewpoint of increasing the contact area with oils and fats, the clay is preferably in powder form.

[0040] In the manufacturing method of the present invention, the amount of clay used is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.75 parts by mass or more, per 100 parts by mass of oil and fat, from the viewpoint of sufficiently reducing 3-MCPDs and glycidols, and the upper limit is preferably 8.0 parts by mass or less, more preferably 7.5 parts by mass or less, and even more preferably 7.0 parts by mass or less, per 100 parts by mass of oil and fat.

[0041] -Conditions for adding white clay- In the manufacturing method of the present invention, the oil temperature when adding the clay is not particularly limited, but it is preferably 70°C or higher, as this makes it easier to obtain refined oil with reduced content of 3-MCPDs and glycidols, and also makes it easier to obtain refined oil with good flavor and color. The oil temperature when adding the clay is more preferably 75°C or higher, even more preferably 80°C or higher, and particularly preferably 85°C or higher, with an upper limit of less than 100°C. Therefore, in a preferred embodiment, the oil temperature when adding the clay is 70°C or higher and less than 100°C, more preferably 75°C or higher and less than 100°C, even more preferably 80°C or higher and less than 100°C, and particularly preferably 85°C or higher and less than 100°C.

[0042] In the manufacturing method of the present invention, when heating the oil to the above temperature, if the oil used is solid at room temperature (25°C), it is preferable to melt it first and then heat it further to reach the above temperature range.

[0043] When heating the oil to the above temperature range in which clay can be added, the heating may be carried out under aerobic conditions, anaerobic conditions, or under reduced pressure. From the viewpoint of suppressing oxidation of the oil during manufacturing, heating under anaerobic conditions or reduced pressure is preferred, and heating under reduced pressure is more preferred. The reduced pressure conditions in this case may be the same as those described in "Reduced Pressure Conditions in the Decolorization Process" above.

[0044] Furthermore, when adding white clay to oils and fats, it may be added in an open atmosphere or under reduced pressure. However, from the viewpoint of preventing oxidation of oils and fats and ensuring a desirable flavor in the resulting refined oils and fats, it is preferable to add the white clay to the oils and fats under reduced pressure. The reduced pressure conditions in this case may be the same as those described in "Reduced Pressure Conditions in the Decolorization Process" above.

[0045] When adding clay in an open atmosphere, if the oil is heated under reduced pressure to a temperature of 70°C or higher but less than 100°C, it is preferable to maintain the oil temperature while introducing an inert gas (e.g., nitrogen gas) into the system to temporarily release the reduced pressure, and then introduce air to open the system to the atmosphere, from the viewpoint of minimizing oxidation of the oil during the refined oil manufacturing process and from the viewpoint of obtaining a desirable flavor of refined oil.

[0046] As described above, in one embodiment, the manufacturing method of the present invention includes a decolorization step of holding the oil at a reduced pressure and an oil temperature of 100°C to 170°C for a period of 10 minutes to 90 minutes.

[0047] In a preferred embodiment, the manufacturing method of the present invention includes a decolorization step in which white clay is added to oils and fats at 70°C or higher and less than 100°C, the mixture is heated under reduced pressure to a temperature of 100°C or higher and 170°C or lower, and the mixture is held under reduced pressure at an oil temperature of 100°C or higher and 170°C or lower for a period of 10 minutes or more and 90 minutes or less.

[0048] In a more preferred embodiment, the manufacturing method of the present invention includes a decolorization step in which oil is heated under reduced pressure to 70°C or higher but less than 100°C, then clay is added to the oil at 70°C or higher but less than 100°C, and the mixture is heated under reduced pressure to 100°C or higher but less than 170°C, and then held under reduced pressure at an oil temperature of 100°C or higher but less than 170°C for a period of 10 minutes or more but less than 90 minutes.

[0049] - Decolorization process method - In the manufacturing method of the present invention, the decolorization step can be carried out using any method, and either a batch method or a continuous method may be used.

[0050] Specific methods for performing the decolorization process in a batch manner include, for example, adding clay to the oil to be decolorized in a heat-resistant container, heating the oil to the decolorization temperature, holding it at that temperature for a certain period of time, and then filtering out the clay from the oil. Alternatively, methods for performing the decolorization process continuously include, for example, filling a filter or column with clay and passing the oil through the filter or column.

[0051] In particular, the decolorization process is preferably carried out in a batch manner because it allows for the processing of a large amount of oil and fat at once, and enables the production of a large amount of refined oil and fat at once.

[0052] When the decolorization process is carried out in a batch manner, for example, the following methods (1) to (3) can be used. (1) A decolorization process in which white clay is added to oil at room temperature (10°C to 30°C: especially 25°C), the oil is heated under reduced pressure until the oil temperature reaches 100°C to 170°C, and the oil is held under reduced pressure at a temperature of 100°C to 170°C for a period of 10 minutes to 90 minutes. (2) A method of decolorizing oils by heating them under reduced pressure to a temperature of 70°C (i.e., the temperature at which most oils and fats, including extremely hardened oils, melt and become liquid) or more but less than 100°C, adding white clay to the oils and fats at 70°C or more but less than 100°C, then heating them under reduced pressure until the oil temperature reaches 100°C or more but less than 170°C, and finally holding them under reduced pressure at an oil temperature of 100°C or more but less than 170°C for a period of 10 minutes or more but less than 90 minutes. (3) A method of decolorizing oil and fat by heating the oil and fat under reduced pressure until it reaches a temperature of 100°C or higher and 170°C or lower, then adding white clay to the oil and fat at 100°C or higher and 170°C or lower, and then reducing the pressure again while maintaining the oil and fat temperature at 100°C or higher and 170°C or lower, and holding the oil and fat at a temperature of 100°C or higher and 170°C or lower under reduced pressure for a period of 10 minutes or more and 90 minutes or less.

[0053] In the methods described in (1) to (3) above, the preferred values ​​and ranges for the reduced pressure conditions (degree of reduced pressure) are as described in "Reduced Pressure Conditions in the Decolorization Process" and so on, and the preferred values ​​and ranges for the decolorization temperature and decolorization time are as described in "Oil Temperature in the Decolorization Process" and "Decolorization Process Time (Decolorization Time)" above. Furthermore, in the method described in (2) above, the preferred values ​​and ranges for the temperature when adding white clay to the oil are as described in "Conditions for Adding White Clay" above.

[0054] While any of the above methods (1) to (3) can reduce the content of one or more of 3-MCPDs and glycidols in the refined oils, method (2) is preferred from the viewpoint of producing refined oils with good flavor and refined oils with excellent color.

[0055] -Deodorization process- From the viewpoint of obtaining refined oils and fats having good flavor and color, the manufacturing method of the present invention preferably includes a deodorizing step after carrying out the decolorization step of the present invention as described above.

[0056] The deodorization process is preferably carried out at an oil temperature of 170°C to 270°C, from the viewpoint of reducing the content of 3-MCPDs and glycidols in the resulting refined oil, or from the viewpoint of suppressing an increase in such content. Therefore, in one embodiment, the manufacturing method of the present invention includes a deodorization process at an oil temperature of 170°C to 270°C after the decolorization process of the present invention. Hereinafter, such a deodorization process may be simply referred to as "the deodorization process of the present invention."

[0057] The oil temperature (deodorization temperature) in the deodorization process is preferably 180°C or higher, more preferably 190°C or higher, and even more preferably 200°C or higher or 210°C or higher, from the viewpoint of producing refined oils with low content of 3-MCPDs and glycidol and good flavor and color, and the upper limit is preferably 270°C or lower, more preferably 260°C or lower, and even more preferably 250°C or lower or 240°C or lower.

[0058] The deodorization process is preferably carried out under reduced pressure, and the reduced pressure conditions are preferably 8.0 × 10⁻⁶. 2 Pa or less, more preferably 6.5 × 10 2 Pa or less or 5.0 × 10 2 It is less than or equal to Pa, and more preferably 2.5 × 10⁻⁶ 2 It is below Pa.

[0059] In the present invention, the deodorization process can be carried out by conventional methods, and the method is not particularly limited. Below, as an example of a specific deodorization method, a deodorization treatment by reduced-pressure steam distillation, in which water vapor and oil are brought into contact under reduced pressure, will be described.

[0060] The oil temperature when contacting the oil with steam in reduced-pressure steam distillation is as described above, and may be set to preferably 190°C to 270°C, more preferably 200°C to 270°C, even more preferably 210°C to 250°C, and particularly preferably 210°C to 240°C.

[0061] The contact time between the steam and the oil in vacuum steam distillation may be set to preferably 30 minutes or more and 180 minutes or less, more preferably 30 minutes or more and 150 minutes or less, and even more preferably 30 minutes or more and 120 minutes or less.

[0062] The amount of steam blown in during vacuum steam distillation may be set to preferably 1% to 5% by mass, more preferably 1% to 4% by mass, and even more preferably 1.5% to 4% by mass, based on 100% by mass of oil and fat.

[0063] -Other processes- The manufacturing method of the present invention may include steps other than the decolorization step and deodorization step described above.

[0064] Other steps besides the decolorization and deodorization steps include, for example, a degumming step to remove phospholipids, a deacidification step to remove free fatty acids, and a dewaxing step to remove wax. The degumming, deacidification, and dewaxing steps can be carried out by conventional methods in oil refining. The conditions and order of the degumming, deacidification, and dewaxing steps are not particularly limited and can be carried out under conditions and in the order normally set for the production of refined oils, however, it is preferable to carry them out at least before the decolorization step of the present invention described above.

[0065] The manufacturing method of the present invention may include a decolorization step other than the decolorization step of the present invention described above. The conditions of the other decolorization step may be the same as or different from those of the decolorization step of the present invention. The other decolorization step may be performed before the decolorization step of the present invention or after the decolorization step of the present invention. The number of times the other decolorization step is performed is not particularly limited. In this specification, if a different decolorization step has been performed n times in advance before the decolorization step of the present invention, the decolorization step of the present invention may be referred to as the "(n+1)th decolorization step". An example of a case where a different decolorization step has been performed n times in advance before the decolorization step of the present invention is to use the aforementioned RBD oil or NBD (Neutralized Bleached Deodorized) oil, which is an oil refined by chemical refining, as the oil used in the manufacturing method of the present invention.

[0066] The manufacturing method of the present invention may include other deodorization steps in addition to the deodorization step of the present invention described above. The conditions of the other deodorization step may be the same as or different from those of the deodorization step of the present invention. The other deodorization step may be performed before the deodorization step of the present invention or after the deodorization step of the present invention. The number of times the other deodorization step is performed is not particularly limited. In this specification, if another deodorization step is performed n times in advance before the deodorization step of the present invention, the deodorization step of the present invention may be referred to as the "(n+1)th deodorization step". An example of a case where another deodorization step is performed n times in advance before the deodorization step of the present invention is the use of the aforementioned RBD oil and NBD oil as the oil used in the manufacturing method of the present invention.

[0067] -Raw material oil- Next, we will describe the raw materials (oils and fats to be refined) to which the manufacturing method of the present invention can be applied.

[0068] The manufacturing method of the present invention can be applied to edible oils and fats without particular limitations. Examples of edible oils and fats include vegetable oils such as palm oil, palm kernel oil, coconut oil, corn oil, olive oil, cottonseed oil, soybean oil, rapeseed oil, rice oil, sunflower oil, safflower oil, cocoa butter, shea butter, mango kernel oil, sal fat, and illipe fat; animal oils such as beef tallow, milk fat, lard, fish oil, and whale oil; and processed oils and fats obtained by subjecting these oils and fats to one or more treatments selected from hydrogenation, fractionation, and transesterification. The manufacturing method of the present invention may be applied to a single oil or fat selected from these, or to a mixed oil or fat obtained by combining two or more types.

[0069] The manufacturing method of the present invention is preferably applied to palm-based oils and fats because its effects are particularly remarkable. In the present invention, palm-based oils and fats refer to palm oil, palm kernel oil, and oils and fats obtained by subjecting palm oil or palm kernel oil to one or more physical or chemical treatments selected from hydrogenation, fractionation, and transesterification. Regardless of which palm-based oil or fat is selected, the manufacturing method of the present invention makes it possible to produce oils and fats with extremely low content of 3-MCPDs and glycidols.

[0070] As mentioned above, 3-MCPD compounds can be produced, in particular, during the deodorization process of oils and fats. Therefore, from the viewpoint of fully obtaining the effects of the manufacturing method of the present invention, it is preferable that the oils and fats used as raw materials are oils and fats that have undergone a deodorization process at least once beforehand. When oils and fats that have undergone a deodorization process at least once beforehand are used as raw materials, there is no particular limit to the number of deodorization processes performed on the raw materials, but from the viewpoint of avoiding deterioration of the oils and fats, it is preferable that it be 5 times or less, more preferably 3 times or less, and even more preferably 2 times or less. The processing conditions of the prior deodorization process may be different from or the same as the processing conditions of the deodorization process of the present invention described above.

[0071] As oils and fats that have undergone the above-mentioned deodorization process at least once, RBD oils and fats obtained by physical refining that have undergone decolorization and deodorization treatment in advance, or NBD oils and fats obtained by chemical refining that have undergone decolorization and deodorization treatment in advance, can be suitably selected.

[0072] -Refined oils and fats obtained by the manufacturing method of the present invention- The refined oils and fats obtained by the production method of the present invention are characterized by having a low content of one or more of 3-MCPDs and glycidols.

[0073] In one embodiment, the refined oils and fats obtained by the production method of the present invention are characterized by a low content of 3-MCPD compounds in the oils and fats. For example, when the production method of the present invention is applied to raw oils and fats in which the total content of 3-MCPD compounds exceeds 3 ppm by mass, the total content of 3-MCPD compounds in the resulting refined oils and fats may be preferably 3 ppm by mass or less, and more preferably 2.5 ppm by mass or less. Furthermore, when the production method of the refined oils and fats of the present invention is applied to raw oils and fats in which the total content of 3-MCPD compounds is less than 3 ppm by mass, the content of 3-MCPD compounds in the resulting refined oils and fats may be further reduced.

[0074] The reduction rate of 3-MCPDs by the manufacturing method of the present invention may, in one embodiment, be preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, 20% or more, 25% or more, or 30% or more. The reduction rate of 3-MCPDs is calculated using the following formula. Reduction rate of 3-MCPDs (%) = (Content of 3-MCPDs in raw oil - Content of 3-MCPDs in the refined oil) / (Content of 3-MCPDs in raw oil) × 100

[0075] The reduction rate of 3-MCPDs indicates the extent to which the content of 3-MCPDs was reduced by going through the decolorization and deodorization processes of the present invention, based on the content of 3-MCPDs in the raw oil (oil before the decolorization process of the present invention).

[0076] In one embodiment, the refined oils and fats obtained by the manufacturing method of the present invention are characterized by a low content of glycidols in the oils and fats. For example, when the manufacturing method of the present invention is applied to raw oils and fats in which the total content of glycidols exceeds 6 ppm by mass, the total content of glycidols in the resulting refined oils and fats can preferably be 2 ppm by mass or less, and more preferably 1 ppm by mass or less. Furthermore, when the manufacturing method of the present invention is applied to raw oils and fats in which the total content of glycidols is less than 6 ppm by mass, the content of glycidols in the resulting refined oils and fats can be further reduced.

[0077] In one embodiment, the reduction rate of glycidols by the method for producing refined oils and fats of the present invention may be preferably 60% or more, more preferably 70% or more, even more preferably 75% or more, even more preferably 80% or more, and particularly preferably 85% or more. The reduction rate of glycidols is calculated using the following formula. Glycidol reduction rate (%) = (Glycidol content in raw oil - Glycidol content in the obtained refined oil) / (Glycidol content in raw oil) × 100

[0078] The reduction rate of glycidols indicates the extent to which the glycidol content was reduced by going through the decolorization and deodorization processes of the present invention, based on the glycidol content in the raw oil (oil before the decolorization process of the present invention).

[0079] There are two main methods for quantifying the content of 3-MCPDs or glycidols in oils and fats: direct analysis and indirect analysis, based on fundamental differences in principle. In this invention, either method may be used for quantification, but indirect analysis is preferred because it requires fewer standard substances and is more economical. For example, a simple indirect analysis method can be used, such as the method described in Japanese Patent No. 5864278 or Oleoscience Vol. 17 No. 4 (2017) pp. 171-178, or a similar method. This method involves hydrolyzing the fatty acid esters of 3-MCPD or glycidol in oils and fats to convert them to 3-MCPD or glycidol, derivatizing them with phenylboric acid, and then measuring them by GC-MS. For example, the measurement conditions for GC-MS can be those described in the "Quantification of 3-MCPDs and Glycidols" section of the Examples Specified.

[0080] In one embodiment, the refined oils and fats obtained by the production method of the present invention are characterized by a low acid value (AV) and good flavor. For example, from the viewpoint of obtaining oils and fats with good flavor, the acid value (AV) of the refined oils and fats obtained by the production method of the present invention is preferably 0.5 or less, more preferably 0.4 or less, even more preferably 0.3 or less, and particularly preferably 0.2 or less. The acid value of an oil or fat is the number of milligrams of potassium hydroxide (mgKOH / g) required to neutralize the free fatty acids present in 1 g of oil or fat. The acid value of an oil or fat can be measured, for example, by the method shown in the Standard Methods for Analysis of Oils and Fats (2013 Edition) 2.3.1-2013 established by the Japan Oil Chemists' Society.

[0081] In one embodiment, the refined oils and fats obtained by the production method of the present invention are characterized by a low peroxide value (POV) and good flavor. For example, from the viewpoint of obtaining oils and fats with good flavor, the peroxide value (POV) of the refined oils and fats obtained by the production method of the present invention is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.5 or less, 0.4 or less, 0.3 or less, or 0.2 or less. The peroxide value (POV) of oils and fats is the number of milliequivalents (meg / kg) of iodine released when peroxides present in 1 kg of oils and fats are reacted with potassium iodide. The peroxide value (POV) of oils and fats can be measured, for example, by the method shown in section 2.5.2 of the Standard Methods for Analysis of Oils and Fats (2013 Edition) established by the Japan Oil Chemists' Society.

[0082] In one embodiment, the refined oils and fats obtained by the manufacturing method of the present invention are characterized by having a good color tone. For example, the color tone of the refined oils and fats obtained by the manufacturing method of the present invention, as measured by the Lovibond method (using a 5 1 / 4 inch cell), is preferably such that Y (yellow) is 25 or less and R (red) is 2.5 or less, and more preferably that Y (yellow) is 20 or less and R (red) is 2.0 or less. The color tone of the refined oils and fats (Lovibon method) can be measured, for example, by the method shown in Section 2.2.1.1 of the Standard Methods for Analysis of Oils and Fats (2013 Edition) established by the Japan Oil Chemists' Society.

[0083] The refined oils and fats obtained by the manufacturing method of the present invention can be used, for example, in the manufacture of food and beverages. Food and beverages using the oils and fats obtained by the manufacturing method of the present invention have the characteristic of having a lower content of 3-MCPDs than conventional food and beverages using oils and fats. Furthermore, in one embodiment, food and beverages using the oils and fats obtained by the manufacturing method of the present invention may have the characteristic of having a lower content of glycidols than conventional food and beverages using oils and fats.

[0084] Examples of food and beverages that use oils and fats include processed foods such as margarine, shortening, fat spreads, flavored fat spreads, dressings, mayonnaise, frozen desserts, spray oils, frying oils, chocolate oils, and batter oils, as well as ingredients for confectionery and bread making such as flour paste and bean paste, Western-style sweets, Japanese-style sweets, bread, snacks, curry, stew, gratin, seasonings, instant prepared foods, processed livestock products, processed seafood products, and processed vegetables. [Examples]

[0085] The present invention will be described in further detail below based on the examples. In the following, "mass%" and "massppm" may be simply referred to as "%" and "ppm". In the following description, unless otherwise specified, the temperature conditions are room temperature (25°C), and unless otherwise specified, the pressure conditions are atmospheric pressure (1013 hPa).

[0086] In the following examples and comparative examples, we used RBD palm oil (manufactured by ISF), which was obtained by physically refining crude palm oil, and was the oil (n=1) that had undergone the first decolorization and first deodorization steps. There were four lots of RBD palm oil used as raw materials, which are denoted as RBD-PO(A), RBD-PO(B), RBD-PO(C), and RBD-PO(D), respectively. In addition, we used "Galleon Earth V2R" manufactured by Mizusawa Chemical Industries, Ltd. as the activated clay. The acidity of the activated clay used in the study was 0.65 (KOH mg / g).

[0087] <Consideration 1> In Study 1, the temperature conditions and the amount of clay added during the decolorization process were changed, and the content of 3-MCPDs and glycidols in the resulting refined oil was measured to evaluate the degree of reduction.

[0088] (Example 1) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(B)) while stirring. In the second decolorization process, the RBD palm oil was heated to 150°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the oil was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added per 100% by mass of the 150°C RBD palm oil. After adding the activated clay, the pressure was reduced again and the oil was heated under reduced pressure to adjust the oil temperature to 150°C, and the decolorization treatment was performed while stirring for 30 minutes under reduced pressure of 133 hPa.

[0089] After the decolorization process, the oil and fat from which the activated clay had been filtered off was subjected to a second deodorization process. In the second deodorization process, steam distillation (3% by mass of steam blown in per 100% by mass of oil and fat) was performed at 230°C for 90 minutes under reduced pressure of 210 Pa to obtain refined oil and fat Ex-1.

[0090] (Example 2) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(C)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then released to the atmosphere to return to atmospheric pressure, and 2.0% by mass of activated clay was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the pressure was reduced again to 133 hPa and heated under reduced pressure to adjust the oil temperature to 150°C, and the decolorization treatment was performed while stirring for 30 minutes under reduced pressure of 133 hPa.

[0091] Next, in the same manner as in Example 1, a second deodorization step was performed on the oil and fat from which the activated clay had been filtered off to obtain refined oil and fat Ex-2.

[0092] (Example 3) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(D)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the pressure was reduced again to 133 hPa and the mixture was heated under reduced pressure to adjust the oil temperature to 150°C. The decolorization treatment was then performed for 30 minutes while stirring under reduced pressure of 133 hPa.

[0093] Next, in the same manner as in Example 1, a second deodorization step was performed on the oil and fat from which the activated clay had been filtered off to obtain refined oil and fat Ex-3.

[0094] (Example 4) The same procedure as in Example 1 was followed to obtain refined oil Ex-4, except that the amount of activated clay added was 4.0% by mass relative to 100% by mass of RBD palm oil.

[0095] (Example 5) The same procedure as in Example 1 was followed to obtain refined oil Ex-5, except that the amount of activated clay added was 6.0% by mass relative to 100% by mass of RBD palm oil.

[0096] (Example 6) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(A)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the pressure was reduced again to 133 hPa and the mixture was heated to adjust the oil temperature to 105°C. The decolorization treatment was then performed under reduced pressure of 133 hPa for 30 minutes while stirring.

[0097] Next, in the same manner as in Example 1, a second deodorization step was performed on the oil and fat from which the activated clay had been filtered off to obtain refined oil and fat Ex-6.

[0098] (Example 7) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(A)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the pressure was reduced again to 133 hPa and the mixture was heated under reduced pressure to adjust the oil temperature to 120°C. The decolorization treatment was then performed under reduced pressure of 133 hPa for 30 minutes while stirring.

[0099] Next, in the same manner as in Example 1, a second deodorization step was performed on the oil and fat from which the activated clay had been filtered off to obtain refined oil and fat Ex-7.

[0100] (Example 8) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(D)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added to 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the mixture was heated again under reduced pressure of 133 hPa to adjust the oil temperature to 135°C, and the decolorization treatment was performed for 30 minutes while stirring under reduced pressure of 133 hPa.

[0101] Next, in the same manner as in Example 1, a second deodorization step was performed on the oil and fat from which the activated clay had been filtered off to obtain refined oil and fat Ex-8.

[0102] (Example 9) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(B)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the mixture was heated again under reduced pressure of 133 hPa to adjust the oil temperature to 165°C, and the decolorization treatment was performed for 30 minutes while stirring under reduced pressure of 133 hPa.

[0103] Next, in the same manner as in Example 1, a second deodorization step was performed on the oil and fat from which the activated clay had been filtered off to obtain refined oil and fat Ex-9.

[0104] (Comparative Example 1) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(B)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the pressure was reduced again and the mixture was heated under reduced pressure to adjust the oil temperature to 90°C. The decolorization treatment was then performed under reduced pressure of 133 hPa for 30 minutes while stirring.

[0105] Next, in the same manner as in Example 1, a second deodorization step was performed on the oil and fat from which the activated clay had been filtered off to obtain refined oil and fat CEx-1.

[0106] (Determination of the content of 3-MCPDs and glycidols) The refined oils obtained were analyzed for their 3-MCPD and glycidol content using an indirect analytical method (indirect quantitative method). The RBD palm oil used as a raw material was also analyzed for its 3-MCPD and glycidol content using the same method.

[0107] In detail, the fatty acid ester of 3-MCPD in oils and fats was hydrolyzed to convert it back to 3-MCPD, which was then derivatized with phenylboric acid and quantified using GC-MS. The GC-MS measurement was performed under the following conditions.

[0108] <Gas Chromatography Department> • Column: VF-5ms ·Injection volume: 1uL • Injection method: Splitless ·Inlet temperature: 250℃ Carrier gas: Helium, 1.2 mL / min Column oven: 60℃: 1 minute → 60~150℃: 10℃ / min, 150~180℃: 3℃ / min, 180~300℃: 30℃ / min, 300℃: 8 minutes. Total: 32 minutes.

[0109] <Mass spectrometry department> Transfer line: 280℃ Ion source temperature: 230℃ ·Quadrupole temperature: 150℃ Ionization method: EI, positive ion

[0110] Furthermore, using the quantitative results, the reduction rates of 3-MCPDs and glycidols were determined by substituting them into the following formulas. Reduction rate of 3-MCPDs (%) = (Content of 3-MCPDs in raw RBD palm oil - Content of 3-MCPDs in the obtained refined oil) / (Content of 3-MCPDs in raw RBD palm oil) × 100 Glycidol reduction rate (%) = (Glycidol content of raw RBD palm oil - Glycidol content of the obtained refined oil) / (Glycidol content of raw RBD palm oil) × 100

[0111] (Measurement of acid value) The acid value (AV) of the refined oils obtained was measured using the method described in Section 2.3.1-2013 of the Standard Methods for Analysis of Oils and Fats (2013 Edition) established by the Japan Oil Chemists' Society.

[0112] (Measurement of peroxide value) The peroxide value (POV) of the obtained refined oils and fats was measured using the method described in Section 2.5.2 of the Standard Methods for Analysis of Oils and Fats (2013 Edition) established by the Japan Oil Chemists' Society.

[0113] (Color measurement) The color tone of the refined oils obtained was measured using the Robibond method (using a 5 1 / 4-inch cell) according to the method described in Section 2.2.1.1 of the Standard Methods for Analysis of Oils and Fats (2013 Edition) established by the Japan Oil Chemists' Society.

[0114] (Evaluation of power) The refined oil obtained was heated to 60°C, 2g was measured out with a teaspoon, and tasted directly. The 12 panelists, who had previously agreed on their evaluation criteria, evaluated whether or not they detected an off-flavor in the oil, according to the evaluation criteria shown below. The average scores are shown in Table 1.

[0115] Evaluation Criteria 10 points: No unpleasant taste when put in the mouth. 9 points: You feel an unpleasant taste 2-3 seconds after putting it in your mouth. 8 points: I felt an unpleasant taste immediately after putting it in my mouth.

[0116] Table 1 shows the raw material oils and fats for each lot, along with the conditions for the second decolorization step, the conditions for the second deodorization step, the content and reduction rate of 3-MCPDs, the content and reduction rate of glycidols, the measured acid value (AV), the measured peroxide value (POV), the measured color, and the evaluation results of the flavor for each example and comparative example.

[0117] [Table 1]

[0118] <Consideration 2> In Study 2, the RBD palm oil used as a raw material was changed, and the content of 3-MCPDs and glycidols in the resulting refined oil was measured to evaluate the degree of reduction.

[0119] (Example 10) Except for using RBD-PO(B) instead of RBD-PO(D), the decolorization process was carried out in the same manner as in Example 3. Then, in the same manner as in Example 1, a second deodorization process was performed on the oil filtered off the activated clay to obtain refined oil Ex-10.

[0120] The refined oil Ex-10 obtained was evaluated in the same manner as in Study 1. The results are shown in Table 2.

[0121] [Table 2]

[0122] From the results of Study 1 and Study 2, it was confirmed that refined oils can be produced by a decolorization process in which oils are held under reduced pressure at an oil temperature of 100°C to 170°C for a period of 10 minutes to 90 minutes, thereby obtaining refined oils with low content of 3-MCPDs and glycidols.

[0123] <Consideration 3> In Study 3, the reduced pressure conditions in the second decolorization process were changed, and the content of 3-MCPDs and glycidols in the resulting refined oil was measured to evaluate the degree of reduction.

[0124] (Example 11) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(E)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the pressure was reduced again and the mixture was heated under reduced pressure to adjust the oil temperature to 135°C. The decolorization treatment was then performed under reduced pressure of 133 hPa for 30 minutes while stirring.

[0125] After the decolorization process, the oil from which the activated clay had been filtered off under a second deodorization process was performed. In the second deodorization process, steam distillation (3% by mass of steam blown in relative to 100% by mass of oil) was carried out at 230°C for 90 minutes under reduced pressure of 150 Pa to obtain refined oil Ex-11.

[0126] (Example 12) The purification process was carried out in the same manner as in Example 11, except that the reduced pressure conditions in the second decolorization step were set to 67 hPa, to obtain refined oil Ex-12.

[0127] (Example 13) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(E)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the pressure was reduced again and the mixture was heated under reduced pressure to adjust the oil temperature to 150°C. The decolorization treatment was then performed under reduced pressure of 133 hPa for 30 minutes while stirring.

[0128] After the decolorization process, the oil and fat from which the activated clay had been filtered off under a second deodorization process was performed. In the second deodorization process, steam distillation (3% by mass of steam blown in relative to 100% by mass of oil and fat) was carried out at 230°C for 90 minutes under reduced pressure of 150 Pa to obtain refined oil and fat Ex-13.

[0129] (Example 14) Except for setting the reduced pressure conditions in the second decolorization step to 67 hPa, the oil was purified in the same manner as in Example 13 to obtain refined oil Ex-14.

[0130] The refined oils Ex-11 to Ex-14 obtained were evaluated in the same manner as in Study 1. The results are shown in Table 3.

[0131] [Table 3]

[0132] From the results of Study 3, it was found that the reduction rate of 3-MCPDs also changes depending on the reduced pressure conditions in the decolorization process. Furthermore, it was found that this change in the reduction rate occurs regardless of the decolorization temperature in the decolorization process.

[0133] <Consideration 4> In Study 4, the acidity of the activated clay used in the second decolorization step or the reduced pressure conditions in the second deodorization step were changed, and the content of 3-MCPDs and glycidols in the resulting refined oil was measured to evaluate the degree of reduction. Furthermore, as examples of activated clay with different acidity levels, we used the aforementioned acidity measurement method to pre-measure the acidity of different lots of "Galleon Earth V2R" manufactured by Mizusawa Chemical Industry Co., Ltd., and used them in our study.

[0134] (Example 15) A second decolorization process was performed on heated and melted RBD palm oil (lot: RBD-PO(E)) while stirring. In the second decolorization process, the RBD palm oil was heated to 90°C under reduced pressure of 133 hPa, then nitrogen gas was introduced to release the reduced pressure, and the mixture was opened to the atmosphere to return to atmospheric pressure. Then, 2.0% by mass of activated clay (acidity 0.55 (KOH mg / g)) was added per 100% by mass of the 90°C RBD palm oil. After adding the activated clay, the pressure was reduced again and the mixture was heated under reduced pressure to adjust the oil temperature to 150°C. The decolorization treatment was then performed under reduced pressure of 133 hPa for 30 minutes while stirring.

[0135] After the decolorization process, the oil from which the activated clay had been filtered off under a second deodorization process was performed. In the second deodorization process, steam distillation (3% by mass of steam blown in relative to 100% by mass of oil) was carried out at 230°C for 90 minutes under reduced pressure of 200 Pa to obtain refined oil Ex-15.

[0136] (Example 16) The activated clay used in the second decolorization step was changed to one with an acidity of 0.65 (KOH mg / g), and the reduced pressure conditions in the second deodorization step were set to 300 Pa. The purification process was carried out in the same manner as in Example 15 to obtain refined oil Ex-16.

[0137] (Example 17) The purified oil Ex-17 was obtained in the same manner as in Example 15, except that the activated clay used in the second decolorization step was changed to one with an acidity of 1.09 (KOH mg / g) and the reduced pressure conditions in the second deodorization step were set to 300 Pa.

[0138] (Example 18) The purified oil Ex-18 was obtained in the same manner as in Example 15, except that the activated clay used in the second decolorization step was changed to one with an acidity of 0.65 (KOH mg / g) and the reduced pressure conditions in the second deodorization step were set to 600 Pa.

[0139] The refined oils Ex-15 to Ex-18 obtained were evaluated in the same manner as in Study 1. The results are shown in Table 4.

[0140] [Table 4]

[0141] From the results of Study 4, it was found that the reduction rate of 3-MCPD compounds changes depending on the acidity of the activated clay used in the second decolorization process. Furthermore, it was found that the reduction rate of 3-MCPD compounds also changes depending on the reduced pressure conditions in the second deodorization process.

Claims

1. A method for producing refined oils in which one or more of 3-monochloropropane-1,2-diols and glycidols are reduced, comprising a decolorization step of adding white clay to oils at 70°C or higher and below 100°C, heating under reduced pressure to 100°C or higher and below 170°C, and holding under reduced pressure at an oil temperature of 100°C or higher and below 170°C for a period of 10 minutes or more and 90 minutes or less.

2. A method for producing refined oils in which one or more of 3-monochloropropane-1,2-diols and glycidols are reduced, comprising a decolorization step in which oils are heated under reduced pressure to 70°C or higher but less than 100°C, then clay is added to the oils at 70°C or higher but less than 100°C, and the mixture is heated under reduced pressure to 100°C or higher but less than 170°C, and then held under reduced pressure at an oil temperature of 100°C or higher but less than 170°C for a period of 10 minutes or more but less than 90 minutes.

3. A method for producing refined oils and fats according to claim 1 or 2, wherein the acidity of the clay used in the decolorization step is 0.50 to 2.50 (KOH mg / g). However, the acidity of the clay is measured and calculated using the methods shown in (1) to (4) below. (1) Measure 10.0 g of clay into an Erlenmeyer flask, add 100 mL of deionized water, shake, and then let stand to mark the water level. (2) Boil this for 5 minutes, let it cool, add deionized water up to the mark, filter the entire volume, and obtain the filtrate. (3) Take 40 mL of the obtained filtrate into another Erlenmeyer flask and add 60 mL of distilled water to obtain 100 mL of sample solution. (4) The sample solution obtained in (3) is titrated with N / 40 potassium hydroxide solution using phenolphthalein as an indicator, and the acidity is calculated using the following formula. [Math 1] A: Acidity (KOH mg / g) B: Titration volume (mL) of N / 40 potassium hydroxide solution C: Moisture content of the sample f: Titer of N / 40 potassium hydroxide solution S: Sample weighing amount (g)

4. A method for producing refined oils and fats according to any one of claims 1 to 3, wherein the above decolorization step is performed on oils and fats that have undergone a deodorization step at least once in advance.

5. A method for producing refined oil and fat according to any one of claims 1 to 4, further comprising a deodorization step at an oil and fat temperature of over 170°C and up to 270°C after the decolorization step described above.

6. A method for producing refined oils and fats according to any one of claims 1 to 5, wherein the vacuum level in the deodorization step performed after the decolorization step is 650 Pa or less.

7. A refined oil obtained by a method for producing refined oils according to any one of claims 1 to 6, wherein the total content of 3-monochloropropane-1,2-diol and its fatty acid esters is 3 ppm by mass or less.

8. A refined oil obtained by a method for producing refined oils according to any one of claims 1 to 7, wherein the total content of glycidol and its fatty acid esters is 2 ppm by mass or less.

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