JP2004166700A - Method for production of acidic oil-in-water type emulsified composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for production of an acidic oil-in-water type emulsified composition having substantial viscosity without increasing amount of thickener even in a formulation system tend to reduce viscosity and having an excellent emulsion stability for a long time. <P>SOLUTION: The method for production of the acidic oil-in-water type emulsified composition comprises an addition of an oil phase after subjecting to a mechanical treatment to increase 50% or more of the viscosity or 5-60% reducing solubility of egg yolk protein of water phase containing egg yolk. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a method for producing an acidic oil-in-water emulsion having a sufficient viscosity and a stable long-term emulsion system.

Acidic oil-in-water emulsions such as mayonnaises and dressings are produced by using egg yolk as an emulsifier, usually preparing an aqueous phase containing egg yolk, and then adding and emulsifying the oil phase. In recent years, the type of oil phase to be blended has been studied from the health perspective, and a blend with a low oil content has been proposed. In particular, it has been revealed that diglyceride has an obesity-preventing effect, a weight-gain suppressing effect, and the like (see Patent Document 1), and attempts have been made to mix it with various foods (see Patent Document 2). However, acidic oil-in-water emulsions such as mayonnaise and the like require emulsification stability, and the incorporation of diglyceride in the oil phase is a factor that results in instability of emulsification.
In industrial-scale mass processing, a water phase and an oil phase are mixed, pre-emulsified, and then manufactured through a fine emulsification step. However, when the load for raising the viscosity in the fine emulsification step is high, the shear energy becomes too high, and the phase may be changed from the O / W emulsion to the W / O emulsion, and it is difficult to perform stable production for a long time. Become. When ordinary fats and oils (triglycerides) are used as the oil phase, an O / W emulsion is easily formed, so that the phase inversion phenomenon hardly appears. However, when diglycerides are contained in fats and oils, there is a problem that phase inversion is likely to occur because diglycerides easily form a W / O emulsion.
In addition, since mayonnaise is used in a manner of being squeezed out of a bottle, it is necessary to have an appropriate viscosity. However, in such a formulation, there is a problem that the flavor is impaired if the amount of egg yolk is simply increased in order to improve the emulsion stability and viscosity.

  Therefore, in order to improve flavor and emulsion stability, a technique using enzyme-treated egg yolk as an emulsifier has been developed (see Patent Document 2). Techniques for improving the viscosity when using normal egg yolk include a method of heat-treating the yolk and a method of first mixing the whole amount of vinegar in the compound with the yolk (see Patent Documents 3 to 5). However, when the enzyme-treated egg yolk is used, or when the oil content in the emulsion is reduced, the viscosity is extremely reduced, and therefore, the heat treatment of the egg yolk or a method of mixing the whole amount of vinegar with the egg yolk cannot be solved.

  On the other hand, if a glyceride mixture containing diglyceride in a high concentration is used for the oil phase, it is reported that an edible oil-in-water emulsion having a rich flavor and a good flavor can be obtained even when the amount of fat is reduced. (See Patent Document 6).

  However, when an acidic oil-in-water emulsion such as mayonnaise in which the oil phase containing a high concentration of diglyceride is emulsified with egg yolk is stored, problems such as cracks, water separation, and reduction in gloss may occur. found. As a technique for solving this problem, for example, it has been reported that these problems can be solved by using lysophospholipid as 15% or more (based on phosphorus amount) of the total phospholipid in the acidic oil-in-water emulsion. (See Patent Document 7).

JP-A-4-300828 JP-A-62-29950 JP-B 1-444309 JP-A-9-172951 JP 2001-120221 A Japanese Patent No. 2848849 JP-A-2001-138

  In the case of producing an acidic oil-in-water emulsion such as mayonnaise, in a large-scale industrial-scale treatment, the emulsion is prepared through mixing and mixing a water phase and an oil phase, preliminary emulsification, and then a fine emulsification step. However, when the load for raising the viscosity in the fine emulsification step is high, the shear energy becomes too high, and the phase may be changed from the O / W emulsion to the W / O emulsion, and it is difficult to perform stable production for a long time. Become. When ordinary fats and oils (triglycerides) are used as the oil phase, an O / W emulsion is easily formed, so that the phase inversion phenomenon hardly appears. However, when diglycerides are contained in fats and oils, the phase transition is likely to occur because the interfacial tension of oil-water is low and a W / O emulsion is easily formed.

  In order to prevent this phase inversion, there is a problem that simply reducing the share in the fine emulsification step does not make the viscosity of the product sufficient. In addition, when enzyme-treated egg yolk is used for emulsification stabilization, or when the oil content in the emulsion is further reduced, the viscosity is reduced, and a thickener may be added to prevent this. is there. However, when the amount of the thickener added is increased, there is also a problem that the flavor and texture are impaired and the quality of the product is reduced.

  Therefore, the present invention, when using diglyceride in the oil phase, even when using enzyme-treated egg yolk for emulsification stabilization, without increasing the thickener, having a sufficient viscosity, even longer An object of the present invention is to provide a method for producing an acidic oil-in-water emulsion having good emulsion stability.

  By the way, in order to improve the long-term storage stability of the acidic oil-in-water emulsion of mayonnaise, and to obtain the viscosity required as a product, it is conceivable to increase the amount of a thickener or to add a new additive. The same effect can be obtained when an oil phase containing a high concentration is used. However, there are problems such as loss of flavor and texture.

  Therefore, the present invention, even when using an oil phase containing a high concentration of diglyceride, without increasing the amount of thickeners and the addition of new additives, stable emulsion system for a long time, sufficient viscosity It is an object of the present invention to provide a method for producing an acidic oil-in-water emulsion having the same.

  Therefore, the present inventors conducted various studies on further stabilization of an emulsified system using egg yolk, and after preparing an aqueous phase containing egg yolk and before adding an oil phase, mechanically treating the emulsion to make the viscosity constant. It has been found that if the treatment is carried out to raise the solubility to a value higher than the range or to lower the solubility of the yolk protein, the viscosity of the acidic oil-in-water emulsion obtained by subsequent emulsification increases and the stability is further improved.

  That is, in the present invention, the oil phase is added after the water phase containing the yolk is mechanically treated to increase the viscosity by 50% or more or the yolk protein solubility by 5 to 60% as compared with that before the treatment. The present invention provides a method for producing an acidic oil-in-water emulsion.

  In addition, the present inventors have conducted various studies to solve the problems specific to the above-mentioned diglyceride-containing acidic oil-in-water emulsion, and usually mixed with the oil phase after adding the entire amount of the acidic substance to the water phase, Reduce the amount of acidic substances in the aqueous phase component before mixing with the phase to below a certain level, add the remaining acidic substances such as vinegar after mixing the aqueous phase component and the oil phase, and lower the pH by 1 or more. It has been found that when emulsification is carried out, the stability and viscosity are significantly improved. In addition, the effect of improving the stability and viscosity by adding most of the acidic substance at the end is hardly obtained in the acidic oil-in-water emulsion using triglyceride as an oil phase, and is hardly obtained in an acidic water containing an oil phase containing diglyceride. It was also found that the effect was peculiar to an oil-type emulsion.

  That is, the present invention provides a method for mechanically treating the aqueous phase containing egg yolk to increase the viscosity by 50% or more or to reduce the yolk protein solubility by 5 to 60% as compared with that before the treatment. And an oil phase containing 20% by weight or more of diglyceride and an acid phase, and then adding an acidic substance to lower the pH by 1 or more.

  By performing the treatment of the present invention, it is possible to increase the viscosity of the aqueous phase before emulsification, and the preliminary emulsified product, so that the load of increasing the viscosity in the fine emulsification step can be reduced, without causing phase inversion. This allows stable production of an emulsion having a sufficient viscosity. In addition, even in the case where the viscosity is reduced, such as when using an enzyme-treated egg yolk, without using a thickener, it has a sufficient viscosity, and further has a long-term good emulsion stability in an acidic oil-in-water type. An emulsion can be produced.

In the method of the present invention, egg yolk is used as an emulsifier, but enzyme-treated egg yolk can also be used to further improve emulsion stability. As the enzyme used for the enzyme treatment of the egg yolk, esterase, lipase, and phospholipase are preferable, lipase and phospholipase are more preferable, and phospholipase is particularly preferable. Among the phospholipases, phospholipase A, ie, phospholipase A ₁ and / or A ₂ is most preferred.
When the enzyme-treated egg yolk is used for the whole of the yolk, the conditions for the lyso ratio (the ratio of the lysophospholipid in all the phospholipids) to be 15% or more based on the phosphorus amount may be appropriately selected. Specifically, when the enzyme activity is 10,000 IU / mL, the amount of the enzyme added is preferably 0.0001 to 0.1% by weight, particularly preferably 0.001 to 0.01% by weight, based on the egg yolk, and the reaction temperature is 20%. The reaction time is preferably from 1 hour to 30 hours, particularly preferably from 5 hours to 25 hours. At the time of the reaction, an arbitrary substance such as salt addition or sugar addition may be added. When enzyme-treated egg yolk is used as a part of the egg yolk, the enzyme treatment conditions may be selected so that the total lyso ratio of the enzyme-untreated egg yolk and the enzyme-treated egg yolk is within the above range. Such an enzyme treatment is preferably performed at a stage before mixing and emulsifying each raw material.

  Egg yolk may be used as it is, or may be used in any form or form such as sterilization, freezing, pulverization, salt addition, and sugar addition. Egg white or whole eggs may be blended. In addition, similarly, in the case of enzyme-treated egg yolk, it can be used in any form.

  In the method of the present invention, first, an aqueous phase containing egg yolk is prepared. The content of egg yolk in the aqueous phase is preferably from 15 to 75% by weight, more preferably from 24 to 55% by weight, particularly preferably from 30 to 45% by weight in terms of liquid egg yolk from the viewpoint of flavor and emulsion stability. In addition, you may mix and add enzyme-treated egg yolk, whole egg, and egg white suitably.

  This aqueous phase contains water; vinegar such as rice vinegar, sake lees vinegar, apple vinegar, grape vinegar, grain vinegar, synthetic vinegar; salt; seasonings such as sodium glutamate; sugars such as sugar and starch syrup; Flavoring agents; various vitamins; organic acids such as citric acid and salts thereof; spices; juices of various vegetables or fruits such as lemon juice; xanthan gum, gellan gum, guar gum, tamarind gum, carrageenan, pectin, soy dietary fiber, tragacanth gum, etc. Thickening polysaccharides; starches such as potato starch, their decomposed products and their modified starches; water-soluble polysaccharides; synthetic emulsifiers such as sucrose fatty acid ester, sorbitan fatty acid ester, polyglycerin fatty acid ester, polysorbate, and soybean Protein emulsifiers such as proteins, milk proteins, wheat proteins, etc., or separated or degraded products of these proteins, Lecithin or natural emulsifiers of the enzymatic decomposition products or the like; can contain various phosphates and the like; dairy products such as milk. In the present invention, these can be appropriately compounded depending on the viscosity, physical properties, and the like of the target composition.

The method of the present invention is characterized in that the aqueous phase is mechanically treated to increase the viscosity by 50% or more or to reduce the yolk protein solubility by 5 to 60% as compared to before the treatment. The mechanical treatment includes stirring, shearing, mixing, homogenizing, kneading and the like. Among these, from the viewpoint of simplicity, a stirring treatment, particularly a strong stirring treatment is preferred. The strength of the stirring treatment is represented by shear energy, and is preferably from 35,000 to 2,000,000 m / s, particularly preferably from 70,000 to 1,000,000 m / s. Here, the shear energy referred to here is the circulation capacity per aqueous phase charged volume by stirring (= the number of times the aqueous phase circulates in the tank by stirring, hereinafter referred to as the "number of circulations") and the "outermost peripheral speed of the stirring blade". (“Technique of the New Stirring Technology” (1989) published by the Technical Information Association).
In addition, in consideration of productivity, when the stirring treatment is performed in the stirring tank, it is not necessary to wash the tank every time, and the raw material such as egg yolk may be added in a state where the emulsion of the previous batch remains.

By this treatment, it is necessary to increase the viscosity by 50% or more or to decrease the yolk protein solubility by 5 to 60% as compared to before the treatment. If the increase in viscosity is less than 50% or the decrease in egg yolk protein solubility is less than 5%, sufficient viscosity and long-term emulsion stabilization effect cannot be obtained. On the other hand, if the yolk protein solubility is reduced to 60% or more, a sufficient viscosity and emulsion stabilizing effect cannot be obtained.
The preferred rate of increase in viscosity is 100 to 500%, more preferably 150 to 300%. The preferred decrease rate of the yolk protein solubility is 10 to 30%.

  The mechanical treatment is particularly preferable because both the above-mentioned increase in viscosity and decrease in egg yolk protein solubility are obtained at the same time, and the flavor is maintained. Therefore, the physical properties (viscosity, long-term emulsion stability and flavor) of the acidic oil-in-water emulsion obtained by manipulating the mechanical treatment conditions can be controlled. As the mechanical treatment, a strong stirring treatment, particularly a stirring tank provided with various stirring blades, is preferable. The rotation direction of the stirring blade does not matter. Examples of other machines include a high-pressure homogenizer such as a mountain gourin and a microfluidizer, an ultrasonic emulsifier, a colloid mill, a line mill, a homomixer, a homohomomixer, and a milder. Note that heat may be generated by shearing force due to mechanical treatment.

  The mechanical treatment may treat only the yolk-derived component.However, in the case where water is blended in the formulation, if the water is added after the mechanical treatment of only the yolk-derived component, the constructed structure becomes Partially disintegrates, and the effect of improving viscosity is reduced. Therefore, when water is blended in the formulation, it is preferable to perform mechanical treatment in a state where a solid seasoning such as salt, sugar, sodium glutamate or the like is dispersed and dissolved in water and a component derived from egg yolk is mixed.

  After mechanical treatment, the oil phase is added. The oil phase is not particularly limited as long as it is a liquid oil at normal temperature, and examples thereof include soybean oil, corn oil, sunflower oil, sesame oil, cottonseed oil, rapeseed oil, safflower oil, palm oil, olive oil, grape seed oil, and the like. Can be In order to obtain an effect such as an obesity prevention effect and a weight suppression effect, it is preferable to use oils and fats containing 20% by weight or more, more preferably 30% by weight or more, particularly 35% by weight or more of diglyceride in the oil phase. . Further, the emulsion stabilizing effect of the method of the present invention is particularly remarkable when the oil phase is a fat or oil containing 20% by weight or more of diglyceride.

  Diglyceride also preferably has a low melting point, and specifically, the constituent fatty acid residue preferably has 8 to 24 carbon atoms, particularly preferably 16 to 22 carbon atoms. The amount of unsaturated fatty acid residues is preferably 55% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more of the total fatty acid residues. Diglyceride can be obtained by any method such as transesterification of glycerin with vegetable oil, animal oil or the like, or esterification of glycerin with fatty acids derived from the above-mentioned fats and oils. The reaction method may be any of a chemical reaction method using an alkali catalyst or the like, and a biochemical reaction method using an oil hydrolase such as lipase. The diglyceride content in the oil phase of the acidic oil-in-water emulsion of the present invention is preferably 20% by weight or more, particularly preferably 30% by weight or more, from the viewpoint of the effectiveness as a lipid metabolism-improved food (inhibiting neutral fat accumulation). The oil phase may contain monoglycerides, free fatty acids and the like in addition to triglycerides and diglycerides. In order to stabilize the emulsion, the oil phase may contain a high melting point fat, particularly a fat which is solid at room temperature.

  The oil phase may further contain a plant sterol having a blood cholesterol lowering effect. The combined use of diglyceride and plant sterol synergistically increases the blood cholesterol lowering effect, and can further enhance the usefulness as a food for improving lipid metabolism. Examples of plant sterols include α-sitosterol, β-sitosterol, stigmasterol, ergosterol, campesterol and the like. In addition, these fatty acid esters, ferulic acid esters, and glycosides can also be used. In the present invention, one or more of these can be used. The content of the plant sterol in the acidic oil-in-water emulsion is preferably 1.2 to 10% by weight, particularly preferably 2 to 5% by weight.

  The weight ratio of the oil phase to the aqueous phase is preferably from 10 to 80:90 to 20, and more preferably from 35 to 75:65 to 25.

After the addition of the oil phase, pre-emulsification is performed as necessary, and the emulsion is finely emulsified to obtain an acidic oil-in-water emulsion. Examples of the fine emulsifier include a high-pressure homogenizer such as mountain gourin and a microfluidizer, an ultrasonic emulsifier, a colloid mill, an azihomomixer, and a milder.
In this fine emulsification step, a large share is applied to the emulsion, but the share also increases as the flow rate increases. Therefore, the present invention is effective when the production scale is large, for example, when the flow rate in the fine emulsification step is 1 kg / min or more, particularly 2 kg / min or more.
Generally, the viscosity of commercially available mayonnaise is about 180 Pa · s, but the viscosity of the mayonnaise produced by the method of the present invention is preferably in the range of 160 to 220 Pa · s.

In the present invention, the aqueous phase containing egg yolk is mechanically treated to increase the viscosity by 50% or more compared to before the treatment or to reduce the yolk protein solubility by 5 to 60%, It is preferable to produce an acidic oil-in-water emulsion by mixing an oil phase containing at least 20% by weight of diglyceride (hereinafter simply referred to as%), and then adding an acidic substance to lower the pH by 1 or more.
At this time, the point is to suppress the amount of acidic substances added to the aqueous phase before mixing with the oil phase to a certain amount or less. In particular, for vinegar (containing 10% acetic acid) among the acidic substances, the amount added to the aqueous phase is 2% or less, preferably 1% or less, more preferably 0%, based on 100% of the whole system, and the rest is oil. It is preferably added after mixing with the phase. Here, the oil phase is an oil or fat containing 20% or more of diglyceride, and preferably has a low melting point. The diglyceride used here is preferably the same as described above. The oil phase may contain a plant sterol as described above. As the yolk used here, those similar to the above can be mentioned.

  The weight ratio of the oil phase to the aqueous phase is preferably from 10 to 80:90 to 20, more preferably from 35 to 75:65 to 25, as described above.

  After mixing the aqueous and oily phases, acidic substances are added to lower the pH by one or more. Examples of acidic substances used here include vinegar such as rice vinegar, sake lees vinegar, apple vinegar, grape vinegar, grain vinegar, and synthetic vinegar; organic acids and salts thereof such as citric acid and succinic acid; various vegetables and fruits such as lemon juice Juice and the like. Among them, vinegar is particularly preferable. The acidic substance not containing vinegar is preferably added to the aqueous phase before being mixed with the oil phase.

  The acidic substance may be added in such an amount as to lower the pH by 1 or more. For example, in the case of vinegar (containing 10% acetic acid), it is preferable to add the acidic substance so as to be 3 to 10%, particularly 5 to 8% in the emulsion. .

  The pH of the aqueous phase after the addition of the acidic substance is preferably 2 to 6, particularly preferably 3 to 5, from the viewpoint of the balance between flavor and storage stability.

  After the addition of the acidic substance, the mixture is uniformly mixed and emulsified to complete the preliminary emulsification, and then finely emulsified to obtain an acidic oil-in-water emulsion. Examples of the fine emulsifier include a high-pressure homogenizer such as a mountain gourin and a microfluidizer, an ultrasonic emulsifier, a colloid mill, an azihomomixer, and a milder, as described above. For mixing and emulsifying various raw materials, there are a batch type production system in which a mixing tank is used and a continuous type production system in which various types of raw materials are continuously fed to a mixer. Further, since the viscosity of general commercially available mayonnaise is about 180 Pa · s, it is preferable that the viscosity of mayonnaise as a final product is also in the range of 160 to 220 Pa · s.

  According to the method of the present invention, it is possible to obtain an acidic oil-in-water emulsion in which the emulsion stability is maintained for a long time. Examples of the acidic oil-in-water emulsion include, but are not limited to, dressing, semi-solid dressing, emulsified liquid dressing, mayonnaise, salad dressing, French dressing, etc. as defined by the Japanese Agricultural Standards (JAS). It is not something that is widely referred to as mayonnaise or dressing.

Example 1
An oil phase and an aqueous phase having the compositions shown in Table 1 were prepared according to the following method so that the total amount was 4.7 kg. First, a purified salt, white sugar, sodium glutamate, mustard powder and citric acid dispersed in water (hereinafter referred to as “seasoned dispersion water”; the same applies hereinafter) and an enzyme-treated egg yolk are added to a mixer having stirring blades. The mixture was stirred for 15 minutes at a rotation speed of 800 r / min using a stirring blade having a blade diameter of 0.144 m under reduced pressure (20 kPa) while adjusting the temperature to 20 ° C. to perform a strong stirring treatment. The amount of seasoning dispersion water charged is 1.23 kg, and the specific gravity of seasoning dispersion water is 1100 kg / m ³ . From the above, the shear energy was defined as “the number of circulations” × “the outermost peripheral speed of the stirring blade”. Therefore, from this condition, the shear energy is calculated by the following equation (published by the Technical Information Association of Japan, Actual "(1989)).
・ Number of circulations = Circulation capacity / Preparation capacity Circulation capacity (m ³ ) = Projection flow coefficient × Blade diameter (m) ³ × Number of rotations (r / min) × Time (min)
= 1 x 0.144 ³ x 800 x 15 = 35.8
Charge capacity (m ³ ) = charge weight (kg) / specific gravity (kg / m ³ ) = 1.23 / 1100 = 0.00112
-Outermost peripheral speed of stirring blade (m / s) = stirring blade diameter (m) x 3.14 x rotation speed (r / min) / 60
= 0.144 x 3.14 x 800/60 = 6
・ Shear energy (m / s) = Circulating capacity / Charging capacity x Outermost peripheral speed of stirring blade
= 35.8 / 0.00112 x 6 = 192000
(The “projection flow coefficient” is a coefficient that varies depending on the shape of the blade, the type of liquid, the temperature, and the like, but in the case of the present application, it is set to 1 for clarification of the definition.)
The viscosity and the protein solubility were measured in each step by the following methods. Next, a soybean polysaccharide dispersed in a 2% oil phase (oil containing a high amount of diglyceride) was added to a mixer, and the mixture was stirred at the same stirring speed for 3 minutes and uniformly mixed, and the stirring peripheral speed was 3 m / s. The remaining oil phase was added with stirring. The pH of the emulsion at this time was 5.5. Thereafter, 10% brewed vinegar was added and mixed to obtain a pre-emulsion having a pH of 4.1. This was finely emulsified with a colloid mill (MZ80: manufactured by FRYMA) at 4200 r / min with a clearance of 0.25 mm to produce mayonnaise (finely emulsified product) having an average emulsified particle diameter of 2.1 μm.

Example 2
In Example 1, mayonnaise was prepared under the same conditions as in Example 1 except that the temperature of strongly stirring the egg yolk and the seasoning dispersion water was 40 ° C, and the subsequent steps were prepared at 20 ° C and pre-emulsified. The viscosity of the dispersion of the egg yolk and the seasoning dispersion water was measured after adjusting the temperature to 20 ° C.

Comparative Example 1
Mayonnaise was prepared under the same conditions as in Example 1, except that the stirring time between the yolk and the seasoning dispersion water was 1 minute. The shear energy at this time is 13000 m / s.

(Preparation of enzyme-treated egg yolk)
Salt concentration of 10% egg yolk solution 750 g, water 150 g, and mixed salt 15 g, was preheated sufficiently at the reaction temperature, adding the amount of phospholipase A ₂ as shown in Table 2 with respect to liquid egg yolk, to obtain enzymatic decomposition yolk Was. Table 1 shows the reaction time, reaction temperature, and lyso conversion. The lyso conversion was calculated by the following method. First, the reaction product was repeatedly extracted with a mixed solvent of chloroform / methanol (3: 1) to obtain all lipids in the reaction product. The obtained lipid mixture was subjected to thin-layer chromatography, and one-dimensional = chloroform: methanol: water (65:25:49), two-dimensional = two-dimensional thin-layer chromatography using butanol: acetic acid: water (60:20:20). The amount of phosphorus in the phospholipids obtained by fractionating various phospholipids was calculated by using a commercially available measurement kit (permanganate ashing method, phospholipid test Wako, manufactured by Wako Pure Chemical Industries, Ltd.). The lysolation ratio (%) was calculated by (total amount of phosphorus in lysophospholipid fraction / total amount of phosphorus in total phospholipid fraction) × 100.

(Viscosity measurement method)
The viscosity is measured in each step, using a B-type viscometer (BH type: Tokyo Keiki),
・ Pre-emulsion and refined emulsion are measured using rotor No. 6, 2r / min, measured value after 30 seconds,
-For a dispersion to which the oil phase other than the pre-emulsion and the fine emulsion was not added in total, the measured values after 30 seconds after rotor No. 2, 20 r / min were used. In addition, the viscosity value at the time of sampling after 15 seconds of stirring was adopted as the point of time when the egg yolk and seasoning water became uniform.

(Protein solubility measurement method)
In general, egg yolk proteins are present in the form of lipoproteins bound to phospholipids. After dissolving and dispersing in saline or the like, centrifugation is performed to classify the supernatant into a supernatant and a precipitate. Is called low-density lipoprotein, and the sediment fraction is called high-density lipoprotein. It is also said that general proteins are hydrophobized by denaturation treatment such as heating, and their solubility in water is reduced. Therefore, in the present application, the degree of denaturation of the yolk protein is first dissolved and dispersed in water to remove insoluble substances by centrifugation, and the supernatant is again dissolved and dispersed in saturated saline and centrifuged. The protein in the dissolved fraction was considered to be native protein and was defined as protein solubility. That is, as the protein denaturation progresses, the protein solubility decreases. The actual measurement method is shown below.

0.15 g of the yolk dispersion containing the enzyme-treated egg yolk or the enzyme-treated egg yolk and each seasoning dispersion water (at the beginning of strong stirring and after strong stirring) is precisely weighed in a sample bottle, and 15 g of distilled water 1) is weighed and mixed. 1.5 g of this solution is placed in a 2 mL centrifuge tube, and the first centrifugation is performed at 15000 r / min for 30 min to remove insoluble substances. After 0.15 g of the upper layer after the centrifugation is precisely weighed in a 2 mL centrifuge tube, 1.5 g of a saturated saline solution is precisely added and mixed, and then the second centrifugation is performed at 20,000 r / min for 1 hour. The centrifugal separator used was a HIMAC centrifuge TYPE SCR20BB (manufactured by Hitachi, Ltd.) and the rotor used was RPR20-3-1169. After the centrifugation, 1 mL of the upper layer (undenatured protein portion) was precisely weighed in a sample bottle, 2 mL of distilled water was precisely weighed, and the concentration thereof was adjusted. Then, ammonium sulfate was measured with a nitrogen analyzer (TN-05; manufactured by Mitsubishi Chemical). Was used as a calibration curve, and the nitrogen concentration was measured. To convert the nitrogen concentration into a protein concentration, the conversion coefficient was multiplied by 7.94 to calculate the protein concentration. In addition, the protein concentration in the enzyme-treated egg yolk used in Example 1 was diluted with seasoning dispersion water mixed during the vigorous stirring treatment, and distilled water was used for centrifugation twice before nitrogen analysis. Each is diluted with a saturated saline solution, and also diluted with distilled water at the time of nitrogen analysis. Therefore, the protein concentration obtained from the nitrogen analyzer is the concentration diluted by these treatments, and the finally used protein solubility is calculated by the following formula in consideration of concentration correction to offset these dilution treatments. Was used.
Protein solubility [%] = ((enzyme-treated egg yolk blending amount at stirring [%] + seasoning dispersion water blending amount at stirring [%]) / enzyme-treated egg yolk blending amount at stirring [%]) x ((enzyme treatment) Egg yolk dispersion amount [g] + distilled water amount 1) [g]) / enzyme-treated yolk dispersion amount [g]) x ((upper sample amount after first centrifugation [g] + saturated saline addition amount [g]) ) / Amount of upper layer sample after first centrifugation [g]) × ((amount of upper layer sample after second centrifugation [g] + amount of distilled water 2) [g]) / upper layer after second centrifugation Sample amount [g]) x (conversion coefficient 7.94) x (nitrogen concentration [%])
As the initial value, the solubility at the time of sampling after 15 seconds of stirring was adopted as the time when the egg yolk and the seasoning water became uniform.

(Stability evaluation method)
Evaluation of emulsification stability of mayonnaise (finely emulsified product) was performed by precisely weighing 30 g of mayonnaise stored at 20 ° C. for 1 month in a 50 mL centrifuge tube, and performing centrifugal separation at 15000 r / min for 30 min. The amount of oil released to the upper layer was measured and calculated as an oil-off amount according to the following equation.

  Oil-off amount (%) = free oil amount after centrifugation (g) / (mayonnaise amount (g) precisely weighed in a centrifuge tube × oil phase amount (67%)) × 100 (%)

(PH measurement method)
The pH of the emulsified product was measured at 20 ° C. using a “PH Controller FD-02” (manufactured by Tokyo Glass Machinery Co., Ltd.) as a pH meter by a usual method.

  The results are shown in Table 3. As is clear from this, when the aqueous phase containing the yolk was stirred until the viscosity increased by 50% or more, or the yolk protein solubility was reduced by 5 to 60%, and the oil phase was added and emulsified, the viscosity and It can be seen that the emulsion stability is particularly excellent.

Claims (7)

  An acidic oil-in-water type in which the aqueous phase containing egg yolk is mechanically treated to increase the viscosity by 50% or more compared to before the treatment or to reduce the yolk protein solubility by 5 to 60%, and then the oil phase is added. A method for producing an emulsion.   The method for producing an acidic oil-in-water emulsion according to claim 1, wherein the oil phase is an oil phase containing 20% by weight or more of diglyceride.   The aqueous phase containing egg yolk is mechanically treated to increase the viscosity by 50% or more compared to before the treatment or to reduce the yolk protein solubility by 5 to 60%, and the obtained aqueous phase and diglyceride are reduced to 20% by weight. A method for producing an acidic oil-in-water emulsion in which the above-mentioned oil phase is mixed, and an acidic substance is added to lower the pH by 1 or more.   The method for producing an acidic oil-in-water emulsion according to claim 3, wherein the acidic substance is mainly composed of vinegar.   The method for producing an acidic oil-in-water emulsion according to any one of claims 1 to 4, wherein the egg yolk is an enzyme-treated egg yolk.   The method for producing an acidic oil-in-water emulsion according to claim 5, wherein the enzyme-treated egg yolk is egg yolk treated with an enzyme selected from esterase, lipase, and phospholipase.   The method for producing an acidic oil-in-water-based emulsion according to any one of claims 1 to 6, wherein the acidic oil-in-water-based emulsion is a mayonnaise.