JP2013059276A - Method for preventing deterioration of fry cooking oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing deterioration of fry cooking oil.SOLUTION: The method for preventing deterioration of fry cooking oil includes the steps of: heating fry cooking oil with which a fry cooking apparatus is filled; and adding gas to the fry cooking oil to form a foam layer on an interface of the fry cooking oil and air. The foam layer preferably occupies 50 to 100% to the area of the interface of the fry cooking oil and the air. More preferably, the foam layer occupies 80 to 100% to the area of the interface of the fry cooking oil and the air.

Description

  The present invention relates to a method for preventing deterioration of oil for frying.

A cooking method in which ingredients are added to a large amount of heated cooking oil is widely used for cooking fries, tempura, fried chicken, fritters, and the like. Heat cooking using frying oil generally heats frying oil to a high temperature of 180 ° C. or higher, and injects ingredients into the frying oil, so heat treatment takes less time than when water is used. In addition to being able to, you can add an oily flavor to the ingredients. Therefore, it is widely used not only in homes but also for business purposes such as restaurants and side dishes stores.
In particular, when the above cooking method is used for commercial use, the frying oil is kept in a high heat state for a long time and the frying oil is in contact with the air for a long time. )Resulting in. Deteriorated frying cooking oil has disadvantages such as bad flavor, low nutritional value, and harmful to human body. Therefore, if the frying oil is rapidly deteriorated, it is necessary to frequently exchange the frying oil, so that there are problems such as an increase in cost and a large load on the environment.
In Document 1, three electrode rods are raised in a stretched manner from a ceramic plate that can be stably placed on a frying pan, and the electric cord connected to each electrode rod is electrically connected to the main body of the device, A frying aid is described in which two bars are provided so that an alternating current can be applied between them, and the remaining electrode bars are grounded. However, the invention described in Document 1 requires a large amount of electric power because a direct current is passed between the electrode bars to electrolyze the frying oil. In addition, the invention described in Document 1 is intended to shorten the heating time and reduce the temperature of the frying oil, and since no data is described regarding the effect of preventing the deterioration of the frying oil, the effect Was unknown.

JP-A-8-56849

  This invention makes it a main subject to provide the deterioration prevention method of the oil for frying cooking.

The present invention includes the following inventions in order to solve the above problems.
[1] It has a step of heating the frying cooking oil filled in the frying cooker and a step of adding gas to the frying cooking oil, and a foam layer is formed at the interface between the frying cooking oil and air. Deterioration prevention method for frying oil.
[2] The method for preventing deterioration of frying cooking oil according to [1], wherein the foam layer occupies 50 to 100% of the area of the interface between frying cooking oil and air.
[3] The method for preventing deterioration of frying oil according to [1] or [2], wherein the foam layer occupies 80 to 100% of the area of the interface between the frying oil and air.
[4] The method for preventing deterioration of frying oil according to any one of [1] to [3], wherein the frying oil is a γ-oryzanol-containing fat.
[5] γ-oryzanol-containing fat is rice oil, palm oil, rapeseed oil, soybean oil, sesame oil, corn oil, cottonseed oil, coconut oil, olive oil, coconut oil, palm kernel oil, safflower oil, sunflower oil, almond oil, One or more selected from the group consisting of cashew oil, hazelnut oil, macadamia nut oil, mongongo oil, pecan oil, pine nut oil, walnut oil, camellia oil, tea oil, beef tallow, lard, chicken oil, horse oil and fish oil The method for preventing deterioration of frying oil according to [4], which is two or more kinds of oils.
[6] The method for preventing deterioration of frying cooking oil according to [4] or [5], wherein the γ-oryzanol-containing fat contains 2% by mass or more of γ-oryzanol.

[7] Deterioration of frying cooking oil according to any one of [1] to [6], wherein the frying oil contains one or more selected from the group consisting of lecithin, monoglyceride, sugar ester and sorbitan. Prevention method.
[8] In any one of [1] to [7], the frying oil contains one or more oils and fats selected from the group consisting of palm oil, palm kernel oil, and medium-chain fatty acid triglyceride (MCT). Deterioration prevention method of the frying cooking oil of description.
[9] The method for preventing deterioration of frying cooking oil according to any one of [1] to [8], wherein the foam layer is generated by adding a gas to the frying cooking oil.
[10] The oil for frying cooking according to any one of [1] to [9], wherein the gas is one or more selected from the group consisting of helium, neon, argon, nitrogen, water vapor, and carbon dioxide. Deterioration prevention method.

  By using the method for preventing deterioration of frying cooking oil of the present invention, deterioration (oxidation) of frying cooking oil can be prevented. More specifically, a foam layer is formed at the interface between the frying oil and air to prevent the frying oil from coming into contact with air (particularly oxygen). In addition, gas is released when the foam disappears, but since the gas layer is formed between the foam layer and the air, it is possible to prevent the frying oil that has formed the foam from coming into contact with the air. . Thereby, deterioration of the oil for frying cooking can be prevented.

It is a figure which shows an example of the deterioration prevention method of the oil for frying cooking concerning this invention. It is a figure which shows an example of the deterioration prevention method of the oil for frying cooking in the aspect different from FIG. It is a figure which shows the change of POV density | concentration of the oil for frying cooking at the time of using oryzanol high content palm oil as frying oil for cooking, and forming a foam layer on the surface of the oil for frying cooking only for 8 hours from a heating start. It is a figure which shows the change of the residual rate of the vitamin E of the oil for frying cooking at the time of using oryzanol high content palm oil as frying oil for cooking, and forming a foam layer on the surface of the oil for frying cooking only for 8 hours from a heating start. .

  The method for preventing deterioration of frying cooking oil according to the present invention includes a step of heating frying cooking oil 2 filled in a frying cooker, and a step of adding gas 4 to frying cooking oil 2. A foam layer 6 is formed at the interface between the oil 2 and air. Hereinafter, the method for preventing deterioration of frying cooking oil according to the present invention will be described with reference to the drawings as necessary.

(Process of heating frying cooking oil)
The method for preventing deterioration of frying oil according to the present invention includes a step of heating the frying oil 2 filled in the frying cooker. The frying cooker includes an oil tank 1 and a heating device 3.
The oil tank 1 is not particularly limited as long as a necessary amount of frying oil 2 can be accommodated, and various frying pans, fryer, and the like for home use and business use can be used. As a frying pan, a frying pan, an iron pan, a Chinese wok, a tabletop frying machine, etc. are mentioned. Examples of the fryer include a gas or electromagnetic cooker, a desktop fryer, an electric fryer, and the like.
The heating device 3 is not particularly limited as long as the cooking oil 2 can be heated to a temperature suitable for cooking the food, and various household and commercial gas cookers and electromagnetic cookers are used. be able to.
In the method for preventing deterioration of frying cooking oil according to the present invention, the temperature of frying cooking oil 2 may be a temperature used for ordinary frying, for example, 130 to 220 ° C.
The oil tank 1 and the heating device 3 may be configured as separate bodies or may be configured as an integral unit.

(Fry cooking oil)
The frying cooking oil 2 used in the present invention is not particularly limited. As the frying cooking oil 2 used in the present invention, rice oil, palm oil, rapeseed oil, soybean oil, sesame oil, corn oil, cottonseed oil, coconut oil, olive oil, coconut oil, palm kernel oil, safflower oil, sunflower oil, Almond oil, cashew oil, hazelnut oil, macadamia nut oil, mongongo oil, pecan oil, pine nut oil, walnut oil, camellia oil, tea oil, beef tallow, lard, chicken oil, horse oil and fish oil, etc. They may be used alone or in combination of two or more. Moreover, these frying cooking oils may use a commercial item, and may be manufactured by a well-known method.

  The frying cooking oil 2 used in the present invention is preferably one that forms a sufficient foam layer 6 by the addition of a gas 4, for example, one or more selected from the group consisting of lecithin, monoglyceride, sugar ester and sorbitan Fats and oils containing two or more, fats and oils containing one or two or more selected from the group consisting of coconut oil, palm kernel oil, and medium-chain fatty acid triglycerides, and γ-oryzanol-containing fats and oils can be suitably used. .

(Gamma-oryzanol-containing fats and oils)
The frying oil 2 used in the present invention is preferably a γ-oryzanol-containing oil. By containing γ-oryzanol, it is possible to obtain fats and oils that easily generate bubbles when the gas 4 is added. By using this as frying cooking oil 2, a sufficient amount of foam layer 6 can be formed at the interface between frying cooking oil 2 and air.

(Addition of γ-oryzanol)
The γ-oryzanol-containing fat used in the present invention is obtained by adding γ-oryzanol to a known oil. γ-oryzanol may be a commercially available product or may be produced by a known method.
Known oils to which γ-oryzanol is added include rice oil, palm oil, rapeseed oil, soybean oil, sesame oil, corn oil, cottonseed oil, coconut oil, olive oil, coconut oil, palm kernel oil, safflower oil, sunflower oil, One from the group consisting of almond oil, cashew oil, hazelnut oil, macadamia nut oil, mongongo oil, pecan oil, pine nut oil, walnut oil, camellia oil, tea oil, beef tallow, lard, chicken oil, horse oil and fish oil Or 2 or more types of fats and oils etc. are mentioned.
The γ-oryzanol content of the γ-oryzanol-containing fat is not particularly limited, but it is preferably 2% by mass or more. More preferably 5% by mass or more, still more preferably 10% by mass or more, and particularly preferably 30% by mass or more.

(Manufacture of fats and oils with high content of γ-oryzanol)
Moreover, you may manufacture the gamma-oryzanol containing fats and oils used for this invention with the manufacturing method including the following processes (A) and processes (B).
(A) Step (B) for obtaining an oil / fat treatment product having an oil layer and an alkali oil cake layer containing a γ-oryzanol salt An acid is added to the oil / fat treatment product obtained in (A), and γ-oryzanol is converted into an alkali. The process of recovering the fats and oils whose γ-oryzanol content is increased by transferring from the oil slag layer to the oil layer

  You may manufacture the gamma-oryzanol containing fat used for this invention by the manufacturing method including processes other than a process (A) and a process (B), unless the objective of this invention is impaired. Examples of steps other than the step (A) and the step (B) include a decolorization step and a deodorization step. Preferably, a decoloring step and a deodorizing step are performed after the step (A) and the step (B). By performing the decolorization step and the deodorization step, a purified γ-oryzanol-containing oil and fat that can be distributed as a product can be obtained. In the decolorization step and the deodorization step, known decolorization methods and deodorization methods that are usually performed in the production process of edible fats and oils can be used.

  The oil-and-fat processed product obtained in the step (A) only needs to have an oil layer and an alkaline oil cocoon layer containing a γ-oryzanol salt. It may consist of only an oil layer and an alkali oil cocoon layer, and may have layers other than these. In the step (A), the processed fat / oil can be obtained by adding an alkali to the raw fat / oil containing γ-oryzanol and separating it into an oil layer and an alkali oil cocoon layer. The raw material fats and oils should just be fats and oils containing (gamma)-oryzanol, and are not limited. Since a large amount of γ-oryzanol is contained in rice bran, it is preferable to use oil derived from rice bran as a raw material fat. It is also known to be contained in corn oil, and it is possible to use corn germ-derived fats and oils as raw material fats and oils.

  Crude oil (rice crude oil) separated by hexane extraction from rice bran as a raw material contains about 2% by mass of γ-oryzanol, most of which is removed by alkaline deoxidation in the deoxidation step. Therefore, the rice crude oil of the previous stage which performs alkali deoxidation at a deoxidation process can be used suitably as raw material fats and oils. Specific examples include rice crude oil immediately after hexane extraction, rice crude oil that has undergone a degumming process, rice crude oil that has undergone a degumming process and a dewaxing process. In addition, since γ-oryzanol removed by alkaline deoxidation in the deoxidation process has been transferred to alkaline oil cake, the oil and fat obtained by acid decomposition of alkaline oil cake (also called dark oil or acid oil). .) Can be suitably used as a raw oil.

  The alkali added to the raw oil and fat is not particularly limited, but a strong alkali is preferable from the viewpoint of deoxidation efficiency and decolorization efficiency. Examples thereof include caustic soda and caustic potash. After adding and stirring an alkali to raw material fats and oils, it can be separated into an oil layer and an alkali oil soot layer by standing, centrifuging, or the like. Although processing temperature is not specifically limited, Usually, it is about 20-80 degreeC, Preferably it is about 30-50 degreeC. The treatment time is not particularly limited, but is usually about 15 minutes to 2 hours, preferably about 30 minutes to 1 hour. The γ-oryzanol contained in the raw oil and fat is neutralized by alkali, forms a salt, and moves to the alkaline oil soot layer. You may add things other than an alkali to raw material fats and oils, unless the objective is impaired. Examples thereof include solvents such as hexane, ethanol, isopropanol, and methanol, but are not limited thereto.

  The amount of alkali added to the raw oil and fat is not particularly limited, but when the free fatty acid is contained in the raw oil and fat, it is preferable to add an alkali equal to or more than the acid value of the free fatty acid. More preferably, it is about 1.2 equivalents or more of the acid value of the free fatty acid. The upper limit is not particularly limited, but about 2 to 4 equivalents are sufficient. The acid value of the free fatty acid can be measured, for example, by titration using alkali blue as an indicator, according to the method described in “2003 Standard Oil Analysis Test Method” (edited by the Japan Oil Chemists' Society).

  Moreover, it is preferable that the amount of alkali added is such that the pH of the resulting alkali oil cake exceeds 10. When the pH of the alkaline oil cake exceeds 10, it is considered that most of γ-oryzanol in the raw material oil and fat forms a salt and easily moves to the alkaline oil cake layer. The upper limit is not particularly limited, but an amount that gives a pH of about 12 to 14 is sufficient.

  In the step (A), an oil-and-fat processed product having an oil layer and an alkaline oil cocoon layer containing a γ-oryzanol salt can also be obtained by layering an oil and fat on an alkaline oil cocoon containing a γ-oryzanol salt. . For example, an alkaline oil cake discharged in the production of rice oil is obtained, and an oil and fat processed product having an oil layer and an alkaline oil cake layer containing a γ-oryzanol salt is obtained by overlaying the oil and fat on this. it can. In addition, by adding alkali to the raw oil and fat containing γ-oryzanol, all the separated oil layer is removed by stirring, standing, etc., and only the alkaline oil soot layer is obtained, and this is overlaid with new oil and fat. May be.

  In the step (B), γ-oryzanol contained in the alkaline oil cocoon layer is transferred to the oil layer by adding an acid to the oil / fat treated product having the oil layer and the alkaline oil cocoon layer obtained in the step (A). . The acid to be added is not particularly limited. For example, hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, citric acid, lactic acid, malic acid, phytic acid, gluconic acid, tartaric acid, butyric acid, oxalic acid, fatty acid, deodorized distillate, etc. Is mentioned. These acids may use only 1 type and may use 2 or more types. Of these, sulfuric acid, phosphoric acid, fatty acid, and deodorized distillate are preferable, and sulfuric acid, phosphoric acid, and deodorized distillate are more preferable. The deodorized distillate is discharged in the deodorizing step in the production of edible fats and oils and is also referred to as scum oil. Since the deodorized distillate contains abundant tocopherols and sterols in addition to free fatty acids, if the deodorized distillate is used as an acid, the tocopherols and sterols in the γ-oryzanol-containing fat obtained by the production method of the present invention Can be strengthened.

  After adding and stirring the acid to the processed fats and oils having an oil layer and an alkali oil cocoon layer, the mixture is allowed to stand, centrifuged, etc., and again separated into an oil layer and an alkali oil cocoon layer, and the γ-oryzanol content of the upper layer Only the oil layer with increased is recovered. Although processing temperature is not specifically limited, Usually, it is about 60-100 degreeC, Preferably it is about 70-90 degreeC. The treatment time is not particularly limited, but is usually about 15 minutes to 2 hours, preferably about 30 minutes to 1 hour. In order to remove soap as much as possible from the obtained oil layer, after collecting the oil layer, water may be added thereto and stirred to remove the separated water layer (soap).

  The amount of acid added in the step (B) is not particularly limited, but it is preferable to add an amount of acid such that the pH of the alkaline oil soot layer is 10 or less. That is, after adding an acid and stirring, it is preferable to add an acid so that the pH of the alkali oil cocoon layer when it is separated into the oil layer and the alkali oil cocoon layer again becomes 10 or less. If the pH of the alkaline oil cocoon layer is 10 or less, it is considered that the γ-oryzanol salt contained in the alkaline oil cocoon layer is easily transferred to the oil layer as free γ-oryzanol. The upper limit is not particularly limited, and an acid may be added in such an amount that the pH of the alkali oil soot layer is about 1 to 3. However, when the pH of the alkaline oil cocoon layer becomes acidic, the fatty acid is released from the free fatty acid salt (soap) in the alkaline oil cocoon layer and moves to the oil layer, so the pH of the alkaline oil cocoon layer becomes 7 or more and 10 or less. More preferably, such an amount of acid is added.

  Since most of the γ-oryzanol in the alkaline oil cocoon layer returns to the oil layer by the step (B), for example, when rice crude oil containing about 2% by mass of γ-oryzanol is used as the raw material fat, about 2 It becomes possible to produce rice oil containing mass% γ-oryzanol. In the technology for efficiently remaining γ-oryzanol contained in the raw oils and fats described in Patent Documents 1 to 4, γ-oryzanol remaining in the refined rice oil is at most about 1.4% by mass, and about 2% by mass. It is difficult to leave γ-oryzanol.

  In the step (A), an alkali is added to the raw oil and fat containing γ-oryzanol and separated into an oil layer and an alkaline oil soot layer containing γ-oryzanol salt to obtain a processed fat and oil, If a part is removed, higher concentration γ-oryzanol-containing fats and oils can be produced than the γ-oryzanol concentration of the raw material fats and oils. At this time, by appropriately increasing or decreasing the amount to be removed from the oil layer, it is possible to obtain γ-oryzanol-rich oil and fat having an arbitrary concentration. Moreover, after adding an alkali to the raw material fat containing γ-oryzanol in the step (A) and separating it into an oil layer and an alkaline oil soot layer containing γ-oryzanol salt, an oil-treated product was obtained. A part of the oil layer may be removed, and new oil may be added to the oil layer. At this time, if different types of fats and oils are added, blended fats and oils containing γ-oryzanol of any concentration can be obtained.

  In the step (A), when the fats and oils are overlaid on the alkaline oil cake containing the γ-oryzanol salt to obtain an oil-treated product, the fats and oils that do not originally contain γ-oryzanol or fats and oils with a low γ-oryzanol content are used. If it uses, arbitrary types of gamma-oryzanol containing fats and oils can be obtained. On the other hand, if γ-oryzanol-containing fats and oils are used as new fats and oils, a higher concentration of γ-oryzanol-containing fats and oils can be obtained. By repeatedly using the obtained γ-oryzanol-rich oil and fat as a new oil and fat again, an oil and fat containing a very high concentration of γ-oryzanol can be obtained.

The oil containing gamma-oryzanol used in the present invention is rice oil, palm oil, rapeseed oil, soybean oil, sesame oil, corn oil, cottonseed oil, coconut oil, olive oil, coconut oil, palm kernel oil, safflower oil, sunflower oil, almond 1 selected from the group consisting of oil, cashew oil, hazelnut oil, macadamia nut oil, mongongo oil, pecan oil, pine nut oil, walnut oil, camellia oil, tea oil, beef tallow, lard, chicken oil, horse oil and fish oil Preferably it is a seed or two or more oils.
The γ-oryzanol content of the γ-oryzanol-containing fat is not particularly limited, but it is preferably 2% by mass or more. More preferably 5% by mass or more, still more preferably 10% by mass or more, and particularly preferably 30% by mass or more. The upper limit of the γ-oryzanol content is not particularly limited, but it is possible to produce an oil containing about 60% by mass of γ-oryzanol.

(Quantitative determination of γ-oryzanol)
The concentration of γ-oryzanol in the frying oil can be measured by a known method. Examples of the γ-oryzanol concentration in the frying oil include the following methods.
Weigh 2-5 g of frying oil and make 100 mL with n-hexane. 2 mL of the sample is taken and the absorbance at 315 nm is measured for a sample diluted to 100 mL with n-hexane. When the weight of the frying oil is X (g) and the absorbance is A, the γ-oryzanol content G (%) can be obtained by the following equation.
G = (A × 5000) / (X × 359)

(Oil obtained by transesterification reaction)
The frying cooking oil 2 used in the present invention is preferably an oil and fat obtained by transesterifying the following (C1) and (C2) in a mass ratio of 5 to 30%.
(C1) Rice oil, palm oil, rapeseed oil, soybean oil, sesame oil, corn oil, cottonseed oil, coconut oil, olive oil, safflower oil, sunflower oil, almond oil, cashew oil, hazelnut oil, macadamia nut oil, mongongo oil, pecan One or more oils selected from the group consisting of oil, pine nut oil, walnut oil, camellia oil, tea oil, beef tallow, lard, chicken oil, horse oil and fish oil (C2) coconut oil, palm kernel One or more oils selected from the group consisting of oils and medium chain fatty acid triglycerides

By transesterifying (C1) and (C2) at the above ratio, oils and fats that are liable to generate bubbles when the gas 4 is added can be obtained. By using the fats and oils obtained by the transesterification reaction as the frying cooking oil 2, a sufficient amount of the foam layer 6 can be formed at the interface between the frying cooking oil 2 and the air.
A known method can be used as the transesterification method. Examples of known transesterification methods include the following methods.
(C1) and (C2) are charged at a molar ratio of 4: 1 in a normal reaction vessel equipped with a stirrer, a heating jacket, a baffle plate, and the like, and a catalyst such as sodium hydroxide is added and mixed with stirring. In a nitrogen gas atmosphere, for example, the transesterification reaction is performed by heating at about 180 to 260 ° C., preferably about 200 to 250 ° C., for about 0.5 to 15 hours, preferably about 1 to 3 hours. The reaction pressure is preferably normal pressure or reduced pressure. After completion of the reaction, the catalyst remaining in the reaction solution is neutralized, and purification treatment such as desalting, decoloring, and filtration is performed.

  The fats and oils obtained by the transesterification may be used alone, for example, rice oil, palm oil, rapeseed oil, soybean oil, sesame oil, corn oil, cottonseed oil, coconut oil, olive oil, coconut oil, palm kernel oil, Safflower oil, sunflower oil, almond oil, cashew oil, hazelnut oil, macadamia nut oil, mongongo oil, pecan oil, pine nut oil, walnut oil, camellia oil, tea oil, beef tallow, lard, chicken oil, horse oil and fish oil You may use it by mixing with 1 type, or 2 or more types of fats and oils from the group which consists of etc. When the fats and oils obtained by the transesterification reaction are used by mixing with other oils, the content in the frying oil 2 is preferably 5% by mass or more, and more preferably 10% by mass or more. 15% by mass or more is particularly preferable.

(Addition of medium-chain fatty acid triglycerides, etc.)
The frying oil 2 used in the present invention preferably contains one or more oils and fats selected from the group consisting of coconut oil, palm kernel oil, and medium chain fatty acid triglyceride (MCT). Since the frying oil 2 contains oils with a low molecular weight such as medium chain fatty acid triglycerides, foam is easily generated when the gas 4 is added, so that a sufficient amount of foam layer at the interface between the frying oil 2 and the air 6 can be formed.
Examples of the medium-chain fatty acid triglyceride used in the frying cooking oil 2 of the present invention include, for example, fatty acids having 6 to 12 carbon atoms, more preferably saturated fatty acids having 6 to 12 carbon atoms, and particularly preferably saturated fatty acids having 8 to 10 carbon atoms. It is done. The medium chain fatty acid triglyceride is preferably caproic acid, caprylic acid, capric acid or lauric acid, and particularly preferably caprylic acid or capric acid.
The content of one or more oils and fats selected from the group consisting of coconut oil, palm kernel oil and medium chain fatty acid triglyceride in the frying oil 2 is preferably 5 to 95% by mass, 7 More preferably, it is -95 mass%, and it is especially preferable that it is 10-90 mass%.

(Addition of MCT etc. and animal fat)
The frying cooking oil 2 used in the present invention includes the following (C2) and (C3), and preferably includes a mass ratio of (C2) and (C3) of 85:15 to 98: 2.
(C2) Palm oil, palm kernel oil and medium chain fatty acid triglyceride (C3) Animal fats such as bird skin, beef tallow, lard

The mixed oil produced from the above (C2) and (C3) uses (C2) as the frying oil, fried deep-fried soup containing the animal fat represented by (C3), and contains 2 to 15% of the components of animal fat. It can be manufactured by shifting the degree to (C2). By mixing (C2) and (C3) at the above ratio, foam is easily generated when the gas 4 is added, and therefore a sufficient amount of foam layer 6 is formed at the interface between the frying oil 2 and air. Can do.
The content of the mixed oil generated from the above (C2) and (C3) in the frying oil 2 is preferably 3% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more. It is particularly preferred that

(Emulsifier addition)
The frying cooking oil 2 used in the present invention preferably contains an emulsifier, preferably contains one or more selected from the group consisting of lecithin, monoglyceride, sugar ester and sorbitan, and adds lecithin. Is more preferable.
Examples of lecithin include high-purity lecithin, enzymatically decomposed lecithin, fractionated lecithin, hydrogenated lecithin, and the like, and any of them may be used.
By adding an emulsifier such as lecithin, monoglyceride, sugar ester, sorbitan, etc., the surface tension of the frying oil 2 is lowered. Thereby, it becomes easy to generate | occur | produce a foam in the oil 2 for frying, and the addition of the gas 4 can form the foam layer 6 of sufficient quantity in the interface of the oil 2 for frying and air.
The content of the emulsifier in the frying oil 2 is preferably 0.01% by mass, more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more. .

(Addition of gas)
The method for preventing deterioration of frying oil according to the present invention includes a step of adding a gas 4 into the frying oil 2. The gas 4 to be added to the frying oil 2 is not particularly limited as long as it has low reactivity with oil, and may be any gas other than oxygen-containing gas such as oxygen and air, but helium, neon, argon It is preferably one or more gases selected from the group consisting of nitrogen, water vapor and carbon dioxide, and nitrogen or water vapor is particularly preferred from the viewpoint of cost and simplicity of the apparatus.
When water vapor is used as the gas 4 to be added to the frying cooking oil 2, water may be added to the heated frying cooking oil 2, and steam may be generated by the heat of the frying cooking oil 2, or the water is heated in advance. It may be added as water vapor. The water used for generating water vapor may be any of hard water, soft water, tap water, and distilled water.
The gas 4 added to the frying oil 2 is preferably added in a high temperature state. The gas 4 is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and particularly preferably 140 ° C. or higher. By setting the gas 4 to the above temperature, the temperature difference between the gas 4 and the frying oil 2 is reduced, and there is an advantage that the temperature of the frying oil 2 is not changed by the addition of the gas 4.

(Gas addition amount)
The addition amount of the gas 4 may be 0.1 to 30 L / min, preferably 0.5 to 20 L / min, and preferably 1 to 10 L / min with respect to 1 kg of frying oil 2. It is particularly preferred. If the amount of gas 4 added is within the above range, a sufficient amount of foam layer 6 can be formed at the interface between the frying cooking oil 2 and the air while keeping the temperature of the frying cooking oil 2 at a high temperature.

(Gas addition device)
In the method for preventing deterioration of frying cooking oil according to the present invention, the gas 4 is added to the frying cooking oil 2 by the gas adding device 5. The gas addition device 5 is not particularly limited as long as the gas 4 produces a sufficient amount of foam in the frying oil 2. The gas addition device 5 adds the gas 4 supplied by a gas storage device such as a cylinder, a gas generation device including a liquid and a heating device, a gas generation device by mixing liquids, or the like to the frying cooking oil 2.
It is preferable to use an injection nozzle, a spray nozzle, a porous nozzle, etc. for the gas addition location where the gas addition device 5 adds gas to the frying oil 2. It is also preferable to form a plurality of pores in the gas addition device 5 and add the gas 4 from the pores. Since the gas addition apparatus 5 can generate fine bubbles by having the above configuration, a sufficient amount of the bubble layer 6 can be formed.

The addition location where the gas 4 is added to the frying oil 2 by the gas addition device 5 is not particularly limited as long as the gas 4 generates a sufficient amount of foam. The addition part may be provided inside the oil tank 1, and the gas 4 may be added inside the frying oil 2. Alternatively, the addition part may be provided outside the oil tank 1, and gas may be provided at the interface between the frying oil 2 and air. 4 may be added, but it is preferable to provide the addition location inside the oil tank 1. Moreover, the addition location of the gas 4 may be provided in one place, or a plurality of places may be provided.
By providing the addition location inside the oil tank 1, the addition location and the gas 4 are heated by the frying cooking oil 2. Thereby, since the gas 4 can be made into the temperature close | similar to the oil 2 for frying, there exists a merit that the temperature of the oil 2 for frying does not change by addition of the gas 4.
When providing the said addition location inside the oil tank 1, the said addition location may be provided in the bottom face vicinity of the oil tank 1, may be provided in the side part of the oil tank 1, and may be provided in the upper part of the oil tank 1.

When providing the said addition location inside the oil tank 1, it is preferable to provide a mesh in the vicinity of the said addition location. When the gas 4 added from the addition part passes through the mesh, the bubbles of the gas 4 are refined, and a sufficient amount of the foam layer 6 can be formed at the interface between the frying oil 2 and the air. The mesh is preferably 40 to 200 mesh / inch, and more preferably 60 to 120 mesh / inch.
The method for preventing deterioration of frying oil according to the present invention preferably includes a stirrer 7 and a stirrer 8. By providing the stirrer 7 and the stirrer 8, the foam generated by the added gas 4 is refined by the stirrer 7, and a sufficient amount of the foam layer 6 is formed at the interface between the frying oil 2 and the air. Can do. Moreover, since the said refined | miniaturized foam is fully spread | diffused with the stirring element 7, a foam can be spread over any part of the interface of the oil 2 for frying cooking, and air.
The stirrer 7 and the stirrer 8 may be physically connected as illustrated in FIG. 1 or may be provided separately as illustrated in FIG. The stirrer 7 may be driven by the power of the stirrer 8 or may be driven by the magnetic force of the stirrer 8.
In addition, the stirrer 8 may be comprised integrally with the apparatus 3 for a heating, and may be comprised as a different body. Moreover, the oil tank 1 and the heating device 3 may have a stirring function.

(Generation of bubbles)
By adding the gas 4 into the frying oil 2, bubbles are generated. The size of the bubbles is not particularly limited, but is preferably fine. The average size of the bubbles may be, for example, 0.01 to 2000 μm, preferably 0.05 to 1500 μm, and more preferably 0.1 to 1000 μm. The size of the bubbles is preferably uniform.
(Foam layer)
The foam layer 6 is generated by adding a gas 4 into the frying cooking oil 2. That is, the gas 4 added to the frying cooking oil 2 generates bubbles, but the bubbles rise to the interface between the frying cooking oil 2 and the air due to the convection of the frying cooking oil 2, and the frying cooking oil 2 A foam layer 6 is formed at the air interface. Contact between the frying oil 2 and air (particularly oxygen) can be prevented. Further, when the bubbles disappear, the gas 4 is released, and a gas layer is also formed between the bubble layer 6 and the air. The gas layer can also prevent contact between the bubble layer 6 and air. Thereby, deterioration (oxidation) of the frying oil 2 can be prevented.
The foam layer 6 may occupy 30 to 100% with respect to the area of the interface between the frying oil 2 and air, preferably 50 to 100%, more preferably 80 to 100%. preferable. When the occupation ratio of the foam layer 6 is within the above range, the frying oil 2 and air are blocked by the foam layer 6, and deterioration of the frying oil 2 can be efficiently prevented.
The thickness of the foam layer 6 is preferably 3 mm or more, more preferably 5 mm or more, and particularly preferably 10 mm or more. When the thickness of the foam layer 6 is within the above range, the frying oil 2 and air are blocked by the foam layer 6, and deterioration of the frying oil 2 can be efficiently prevented.
The bubble layer 6 is generated by the addition of the gas 4 and disappears rapidly when the addition of the gas 4 is stopped. That is, the foam layer 6 in the present invention is derived from the foam generated by the addition of the gas 4 to the frying cooking oil 2 and is not derived from the foam generated by the deterioration of the frying cooking oil 2. The amount of foam generated can be controlled by the amount of gas 4 added to the frying oil 2.

By using the method for preventing deterioration of frying cooking oil of the present invention, deterioration (oxidation) of frying cooking oil can be prevented. More specifically, the foam layer 6 is formed at the interface between the frying cooking oil 2 and the air to prevent the frying cooking oil 2 from coming into contact with air (particularly oxygen). Moreover, when the foam disappears, the gas 4 is released, but since the layer of the gas 4 is formed between the foam layer 6 and the air, the frying oil that has formed the foam comes into contact with the air. Can also be prevented. Thereby, deterioration of the frying oil 2 can be prevented.
With the method for preventing deterioration of frying cooking oil according to the present invention, it is possible to suppress a decrease in vitamin E content in frying cooking oil 2. That is, consumption of vitamin E due to deterioration of frying oil can be suppressed.
Moreover, the increase in the peroxide (POV) in the frying oil 2 can be prevented by the method for preventing deterioration of frying oil according to the present invention. That is, an increase in POV concentration due to deterioration of frying oil can be suppressed.
As described above, according to the method for preventing deterioration of frying cooking oil of the present invention, adverse health effects caused by intake of deteriorated frying cooking oil can be prevented. Moreover, since the same frying cooking oil can be used repeatedly, the cost required for cooking can be reduced and the burden on the environment can be reduced.

  In the method for preventing deterioration of oil for frying according to the present invention, the ingredients can be fried by adding the ingredients. The ingredients may be fried as they are, or may be fried and cooked with flour, bread crumbs or the like. Ingredients used in the present invention include, for example, croquettes, tonkatsu, fried chicken, fried chicken, ham cutlet, deep-fried, Tatsuta fried, fritter, fried seafood, fried meat, fried vegetables, fried oysters, deep-fried fish cake, deep-fried fish, deep-fried fish Fried, scissor fried, scotch egg, tempura, french fries, fried meat dumplings, pre-fried tempura, samosa, fried bread, fried rice crackers (fried rice crackers, etc.), fried snack, fried chicken, sweet potato fried, American dog, curry bread, Examples include donuts, piroshki, dumplings, and spring rolls.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

(Reference Example 1) Production of palm oil with high oryzanol content (1) Step (A)
1000 g of rice oil that has undergone the degumming and dewaxing process is heated to 40 ° C., 16.86 g of a 25.5 mass% aqueous sodium hydroxide solution and 33.73 g of water are added, and the mixture is stirred for 30 minutes to separate into an oil layer and an alkaline oil slag layer .

(2) Process (B)
All of the oil layer was removed to obtain an alkaline oil layer. Add 120 g of RBD palm oil (acid value: 0) to 120 g of the obtained alkali oil cocoon layer, add 40 g of deodorized distillate (scum oil), heat to 80 ° C. with stirring, and centrifuge to remove the oil layer. 1040 g was obtained. Warm water at 40 ° C. was added to the obtained oil layer, centrifuged again, and soap was removed to obtain acid-treated oil.

(3) Decoloring step 20 g of activated clay was added to the acid-treated oil, heated to 8000 Pa and 120 ° C., and then filtered to obtain a decolorized oil.

(4) Deodorizing step The decolorized oil was heated to 1300 Pa and 240 ° C to remove odorous components, thereby obtaining oryzanol-containing palm oil.

(Reference Example 2) Production of rice oil with high oryzanol content (1) Step (A)
100 kg of rice oil that has undergone the degumming and dewaxing process is heated to 40 ° C., 1.69 kg of a 25.5% by weight aqueous sodium hydroxide solution and 3.37 kg of water are added, and the mixture is stirred for 30 minutes to form an oil layer and an alkaline oil soot layer. separated.

(2) Process (B)
0.82 kg of 75% phosphoric acid aqueous solution was added to this, heated to 80 ° C. with stirring, and then centrifuged to obtain 90 kg of an oil layer. Warm water at 40 ° C. was added to the obtained oil layer, centrifuged again, and soap was removed to obtain acid-treated oil.

(3) Decolorization process 4.5 kg of activated clay was added to the acid-treated oil, heated to 8000 Pa and 120 ° C. and then filtered to obtain a decolorized oil.

(4) Deodorizing step The decolorized oil was heated to 1300 Pa and 240 ° C to remove odorous components, and rice oil with a high oryzanol content was obtained.

(Heating of cooking oil for frying)
500 g of frying oil was placed in an aluminum block thermostatic bath, and the oil temperature was maintained at 180 ° C. while stirring relatively gently with a magnetic stirrer. After the oil temperature reached a predetermined temperature, steam was added to the frying cooking oil. The foam generated from the frying oil was stirred with a magnetic stirrer to make fine foam. Ingredients were not added to the cooking oil.
An injection nozzle was provided inside the aluminum block thermostatic chamber, near the bottom surface, and gas was added from here. A fixed amount of distilled water (1 ml / min) was supplied to the frying oil using a metered water pump. Since the spray nozzle was heated to the same temperature as the oil inside the frying oil, the supplied distilled water was added as steam to the frying oil.

(Measurement)
The oryzanol content (hereinafter referred to as OZ (%)) in the frying oil was measured by the following method.
Weigh 2-5 g of frying oil and make 100 mL with n-hexane. 2 mL of the sample is taken and the absorbance at 315 nm is measured for a sample diluted to 100 mL with n-hexane. When the weight of the frying oil is X (g) and the absorbance is A, the γ-oryzanol content G (%) was determined by the following equation.
G = (A × 5000) / (X × 359)

The acid value in the oil for frying (hereinafter referred to as AV (mgeq / kg)) is described in “2003 Standard Oil Analysis Test Method” (edited by the Japan Oil Chemists' Society, hereinafter referred to as “Standard Oil Analysis Method”). According to the method of, it measured by titration. However, alkali blue indicator was used for the frying cooking oil containing γ-oryzanol.
The peroxide value in the frying oil (hereinafter referred to as POV (mgeq / kg)) was measured by a method according to the standard fat analysis method.
ΔPOV was determined by (POV content at each time) − (POV content at 0 hour heating time).
The content of vitamin E (hereinafter referred to as VE) in the frying oil was determined by summing the contents of tocopherol and tocotrienol. The contents of tocopherol and tocotrienol in the frying cooking oil were determined by a method according to the standard fat analysis method.
The VE residual rate (%) was determined by (VE at 8 hours after the start of heating) / (VE at 0 hour after the start of heating) × 100.
The area occupied by the foam layer was calculated by taking a picture of the state of foam generation 10 minutes after the start of feeding distilled water to frying cooking oil and analyzing the image. The thickness of the foam layer was calculated by image analysis of a bubble generation state 10 minutes after the start of feeding the distilled water.

(Evaluation)
In the present specification, when the analysis value of POV at a heating time of 8 hours is +2.5 or less with respect to the analysis value of POV at a heating time of 0 hour, the evaluation of POV is evaluated as ◯. In addition, when the VE residual rate (%) at the heating time of 8 hours was 80 or more, the evaluation of VE was evaluated as ◯.

Example 1
The oryzanol-rich palm oil produced in Reference Example 1 was used as the frying oil. Water vapor was added to the frying oil until 8 hours had elapsed from the start of heating to form a foam layer at the interface between the frying oil and air. For 30 minutes from the elapse of 8 hours from the start of heating, the addition of the gas into the frying oil was stopped, and no steam bubbles were generated. After the temperature of the frying oil became constant at 180 ° C., about 50 ml of the frying oil was collected at an elapsed time of 0 hours, 4 hours, 8 hours, and 8 hours and a half, and the components were measured.

(Example 2)
The experiment was conducted under the same conditions as in Example 1 except that high-oryzanol-containing palm oil produced in Reference Example 1 and having a composition different from that in Example 1 was used as the frying cooking oil.
The results are shown in Table 1.

(Evaluation)
In both Examples 1 and 2, the numerical values of POV and ΔVE were improved at 8 hours from the start of heating compared to the values at the start of heating. After the addition of gas was stopped when 8 hours from the start of heating, the numerical values of POV and ΔVE both deteriorated, and the frying oil deteriorated (oxidized). Therefore, it turned out that deterioration of the oil for frying cooking can be prevented by a foam layer. Similarly, the amount of OZ in the frying oil was also suppressed until 8 hours after the start of heating, but it was found that the amount decreased rapidly after the addition of gas was stopped after 8 hours from the start of heating. (See FIGS. 3 and 4).
In both Example 1 and Example 2, the AV after the start of heating was at a level that had no problem at all with respect to the standards of the Food Sanitation Law.

(Example 3)
As the frying oil, the oryzanol-rich rice oil produced in Reference Example 2 was used. Water vapor was added to the frying oil until 8 hours had passed since the start of heating. At an elapsed time of 0 hour, 4 hours, and 8 hours, about 50 ml of frying oil was sampled and the ingredients were measured.

Example 4
The experiment was conducted under the same conditions as in Example 3 except that high-oryzanol-containing palm oil produced in Reference Example 1 and having a composition different from that of Example 1 was used as the frying cooking oil.

(Examples 5 and 6)
The experiment was conducted under the same conditions as in Example 3 except that high-oryzanol-containing rice oil produced in Reference Example 2 and having a composition different from that in Example 3 was used as the frying cooking oil.

(Example 7)
The same conditions as in Example 3 except that γ-oryzanol was added to a mixed oil of rapeseed oil and medium-chain fatty acid triglyceride (MCT) (mixing ratio 80:20 (v / v)) as the frying oil. The experiment was conducted.
The results of Examples 3 to 7 are shown in Table 2.

(Evaluation)
In all of Examples 3 to 7, both POV and ΔVE showed good numerical values. Therefore, it was found that the frying layer can prevent deterioration (oxidation) of the frying oil. Moreover, the reduction | decrease of OZ by frying cooking could also be suppressed.
In all of Examples 3 to 7, the AV after the start of heating was at a level that had no problem at all with respect to the standards of the Food Sanitation Law.

(Comparative Examples 1-15)
The experiment was performed under the same conditions as in Example 3 except that the frying oil was set as described in Table 3. In Comparative Examples 1 to 15, a commercial product was used as the frying oil. The results are shown in Table 3.

(Evaluation)
None of Comparative Examples 1 to 15 had excellent values for both POV and ΔVE.

  According to the method for preventing deterioration of oil for frying food of the present invention, the deterioration of oil for frying can be prevented and the cost required for frying can be reduced, which is industrially useful.

DESCRIPTION OF SYMBOLS 1 Oil tank 2 Oil for frying 3 Heating equipment 4 Gas 5 Gas addition apparatus 6 Foam layer 7 Stirrer 8 Stirrer

Claims (10)

Heating the frying cooking oil filled in the frying cooker;
Having a step of adding gas to the frying oil,
A method for preventing deterioration of frying cooking oil in which a foam layer is formed at the interface between frying cooking oil and air.   The method for preventing deterioration of frying cooking oil according to claim 1, wherein the foam layer occupies 50 to 100% of the area of the interface between frying cooking oil and air.   The method for preventing deterioration of frying cooking oil according to claim 1 or 2, wherein the foam layer occupies 80 to 100% of the area of the interface between frying cooking oil and air.   The method for preventing deterioration of frying cooking oil according to any one of claims 1 to 3, wherein the frying oil is γ-oryzanol-containing fat.   γ-Oryzanol-containing fat is rice oil, palm oil, rapeseed oil, soybean oil, sesame oil, corn oil, cottonseed oil, coconut oil, olive oil, coconut oil, palm kernel oil, safflower oil, sunflower oil, almond oil, cashew oil, One or more selected from the group consisting of hazelnut oil, macadamia nut oil, mongogo oil, pecan oil, pine nut oil, walnut oil, camellia oil, tea oil, beef tallow, lard, chicken oil, horse oil and fish oil The method for preventing deterioration of oil for frying according to claim 4, wherein the oil is oil.   The method for preventing deterioration of frying cooking oil according to claim 4 or 5, wherein the γ-oryzanol-containing fat contains 2% by mass or more of γ-oryzanol.   The method for preventing deterioration of frying cooking oil according to any one of claims 1 to 6, wherein the frying cooking oil contains one or more selected from the group consisting of lecithin, monoglyceride, sugar ester and sorbitan.   The frying oil for frying according to any one of claims 1 to 7, wherein the frying oil contains one or more oils and fats selected from the group consisting of coconut oil, palm kernel oil, and medium chain fatty acid triglyceride (MCT). Oil deterioration prevention method.   The method for preventing deterioration of frying cooking oil according to any one of claims 1 to 8, wherein the foam layer is generated by adding a gas to the frying cooking oil.   The method for preventing deterioration of frying cooking oil according to any one of claims 1 to 9, wherein the gas is one or more selected from the group consisting of helium, neon, argon, nitrogen, water vapor and carbon dioxide.

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