JP2007074909A - Edible emulsion and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide new edible emulsion not requiring use of thickener, utilizing phospholipid and excellent in temporal stability: and to provide a method for producing the emulsion. <P>SOLUTION: The edible emulsion comprises an emulsification dispersant consisting mainly of a mixed liquid crystal obtained by mixing edible oil with phospholipid and fatty acid ester, as essential ingredient. The mixed liquid crystal preferably comprises such one as to be obtained by mixing soybean phospholipid with fatty acid sucrose ester, wherein mass fraction of the soybean phospholipid and the fatty acid sucrose ester are preferably set to 0.1≤Ws<0.8 assuming that the mass of the soybean phospholipid corresponds to M1, the mass of the fatty acid sucrose ester corresponds to M2, and the mass fraction Ws corresponds to M2/(M1+M2). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an edible emulsion excellent in temporal stability obtained for various edible oils and a method for producing the same.

  The emulsifier for food needs to be designated as a food additive since physiological safety is regarded as the most important, and has extremely large restrictions compared to an industrial emulsifier. Currently, the main food additives permitted in Japan are roughly classified into five types: synthetic additives glycerin fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, and natural additive lecithin. .

  When selecting an emulsifier in a complex system such as food, the combination of emulsifiers, the influence of coexisting substances on emulsification, and the mixing ratio must be examined. Moreover, in the emulsification of food, when a large amount of emulsifier is required, the flavor may be impaired, and preparation of a stable emulsion of edible vegetable oil is generally difficult. Therefore, in general, food emulsions are apparently stabilized by adding a thickener in order to suppress oil aggregation and separation (Non-patent Document 1).

By the way, phospholipids are representative lipids present in biological membranes such as biological cells and blood, and are excellent in biodegradability, physiological mildness, and emulsifying power. Used in fields such as agricultural chemicals and cosmetics. Phospholipids are soluble in organic solvents and insoluble in water. It is known that when this is dispersed in water, a lyotropic liquid crystal in which a hydrophilic group site and a hydrophobic group site are regularly aligned is formed and a lamellar structure is formed. Further, this bilayer membrane of phospholipid is used as an emulsifier, and changes into spherical vesicles called vesicles when subjected to ultrasonic waves or solvent substitution (Non-patent Document 2). Since this vesicle has a higher encapsulation rate than lamellar liquid crystals having a layered structure, it is expected to be put to practical use as a drug delivery (DDS) (Non-patent Document 3).
Edited by Japan Oil Chemists' Society Hiroshi Terada, Tetsuro Yoshida Liposome Springer Fairlark Tamio Yamakawa and others

  However, it has been confirmed that the phospholipid emulsion becomes unstable due to a change in the state of the bilayer liquid crystal after 3 months, that is, a gelation phenomenon, when the average particle size at the time of emulsion formation is larger than 800 nm. It is difficult to put edible oil into practical use as an emulsifying material. For this reason, when forming an edible emulsion using a phospholipid, the further device which stabilizes an emulsion is needed.

  The present invention has been made in view of the circumstances as described above, and provides a new edible emulsion that does not require the use of a thickener and has excellent temporal stability using a phospholipid, and a method for producing the same. This is the main issue.

  In the emulsification method using a general surfactant, the surfactant is adsorbed on the interface between oil and water, and the basic energy of the emulsification / dispersion method is to reduce the interfacial energy. Therefore, a large amount of an emulsifying dispersant is required. On the other hand, the present inventors do not dissolve the molecules of phospholipid in water, and the bilayer liquid crystal formed by the phospholipid itself adheres to the surface of the oil droplets by van der Waals force. , Forming a three-phase structure of an aqueous phase, forming an emulsion with excellent stability over time, and adding a predetermined surfactant to a phospholipid bilayer to form a mixed liquid crystal. It was found that it was possible to subdivide and avoid the gelation phenomenon, and the present invention was completed.

  That is, in order to achieve the above object, the edible emulsion according to the present invention contains an emulsifying dispersant containing, as an essential component, a mixed liquid crystal obtained by mixing a phospholipid and a fatty acid ester in edible oil. It is characterized (claim 1).

Here, edible oil is assumed to be soybean oil, rapeseed oil, olive oil, rice squeeze oil, functional additive oil (tocopherol (vitamin E), limonene (fragrance)), etc. (Claim 5), Soybean phospholipid (soybean lecithin) and egg yolk phospholipid (egg yolk lecithin) are suitable. As the fatty acid ester to be mixed with phospholipid, fatty acid esters (glycerin fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, etc.) which are food additives are suitable (Claim 6). A mixed liquid crystal formed by mixing soybean phospholipid and fatty acid ester may be used (claim 2). In this case, when fatty acid sucrose ester is used as the fatty acid ester, the mass fraction of soybean phospholipid and fatty acid sucrose ester is M1, the mass of the soybean phospholipid, and the mass of the fatty acid sucrose ester is M2. When the rate Ws is expressed by M2 / (M1 + M2), it is preferably set in a range of 0.1 ≦ Ws <0.8.

  In addition, the composition of the edible emulsion may be such that the weight ratio is 0.05 to 20% of the phospholipid, 0.005 to 8.0% of the fatty acid ester, 10 to 90% of edible oil, and water balance. (Claim 4).

  In preparing the edible emulsion, the phospholipid and the fatty acid ester are mixed so as to have a predetermined mass fraction, and water is added so that the weight ratio of the phospholipid is a predetermined weight percent. Then, the dispersion is used as an aqueous phase, and an emulsion may be prepared so that the weight ratio of the oil phase is a predetermined weight percent (Claim 7). At this time, the dispersion is preferably stabilized by repeating the step of stirring the dispersion at a high temperature and then aging.

  As described above, according to the present invention, an emulsifying dispersant mainly composed of an amphiphilic substance composed of a mixed liquid crystal of phospholipid and a food emulsifier, specifically, soybean lecithin and a fatty acid ester is used as an edible oil. Therefore, it is possible to form an edible emulsion with excellent stability over time that does not cause a gelation phenomenon.

  The best mode of the present invention will be described below.

[Reagent used]
In the following experiments, the following reagents were used.
1. Nonionic surfactant
As a polyoxyethylene alkylether (C ₁₄ H ₂₉ (OC ₂ H ₄ ) ₈ OH; molecular weight 566.83 g · mol ⁻¹ ), a synthetic product (NIKKOL) was used as it was.

2. Phospholipids As the phospholipids, 1,2-Dimyristoyl-sn-gloycero-3-phosphocholine (hereinafter, DMPC; molecular weight 677.94 g · mol ⁻¹ ) represented by the following chemical formula ¹ was used as it was, and a synthetic product of Avanti Polar Lipids was used as it was. . This phospholipid is a two-chain zwitterionic surfactant.

3. Table 1 shows the food emulsifiers used. In addition, the chemical structure of soybean lecithin (SLP) in Chemical Formula 2, the molecular structure of sucrose fatty acid ester in Chemical Formula 3, the molecular structure of sorbitan fatty acid ester in Chemical Formula 4, the molecular structure of polyglycerin fatty acid ester in Chemical Formula 5, Chemical formula 6 shows the molecular structure of the fatty acid propylene glycol ester, respectively.
All provided were used as they were.

4). The water used was purified by ion-exchanged water (MILLPORE ultrapure equipment, Nihon Millipore) and then distilled water. The pH was 7.0 to 7.1 (25 ° C.).

5. Oil used
(1) As hexadecane, a synthetic product of ALDRICH (pure water 99% or more, d = 0.773 g · dm ⁻³ , molecular weight; 226.45 g · mol ⁻¹ ) was used as it was.
(2) Triolein (molecular weight; 885.43 g · mol ⁻¹ ) was purchased from Wako Pure Chemical Industries, Ltd.
(3) The liquid paraffin used was purchased from Wako Pure Chemical Industries, Ltd.
(4) The vegetable oil used was the same as that provided by Yokohama Yushi Kogyo Co., Ltd. Composition is soybean oil (C18: F ₂ ; 52.6%, C18; F ₁ ; 24.2%, C16; 10.7%), rapeseed oil (C18; F ₁ ; 61.3%, C18: F ₂ 20.2%, C18: F ₃ ; 9.0%), rice bran oil (C18; F ₁ ; 42.3%, C18: F ₂ ; 35.7%, C16; 16.1%). C is the carbon chain length and F is the number of unsaturations.

[Preparation of dispersion]
The mixed liquid crystal dispersion used as an emulsifier was prepared by the following two methods.
(1) Preparation of Mixed Liquid Crystal Dispersion Performed by the Inventor DMPC and surfactant were each uniformly dissolved in ethanol. Thereafter, in order to obtain a predetermined mixed composition, the surfactant / ethanol solution was added to the DMPC / ethanol solution and sufficiently stirred. Next, ethanol was removed under reduced pressure overnight at room temperature to prepare a mixed crystal of DMPC and a surfactant. Water was added to the mixed crystal and dispersed so that DMPC was 0.5 wt%. Next, the mixture was stirred with Vortex for 5 minutes, immersed in warm water at 35 ° C. for 5 minutes, then stirred with Vortex for 5 minutes, immersed in ice water for 5 minutes, and finally stirred with Vortex for 5 minutes. This operation was repeated three times, and the mixture was aged in a constant temperature bath at 35 ° C. where the lamellar liquid crystal of phospholipid DMPC was thermally stable (29.5 ° C.) or higher to obtain a stable mixed liquid crystal state.
(2) Preparation of mixed liquid crystal dispersion for practical use Add phospholipid SLP of food emulsifier and various food emulsifiers to a predetermined mass fraction, and add water so that SLP is 0.5 wt%. In addition, it was dispersed. The dispersion was stirred with a homogenizer for 5 minutes, immersed in warm water at 60 ° C. for 5 minutes, stirred with a homogenizer for 5 minutes, immersed in ice water for 5 minutes, and finally stirred with a homogenizer for 5 minutes. This was repeated three times and aged overnight at room temperature.

[Preparation of emulsion]
The emulsion was prepared by the following two methods.
(1) Preparation of Emulsion Performed by the Inventor Oil is added to the emulsifier phase so as to have a predetermined composition, and a bath-type ultrasonic generator (Elma) for 3 minutes with a finger-type ultrasonic generator (OHTAKE WOEKS 5202 PZT). Irradiated with TRANSSONIX 570) for 2 minutes. This operation was repeated twice to emulsify.
(2) Preparation of emulsion for practical use An oil phase is added to the emulsifier phase so as to have a predetermined mass ratio (added to the emulsifier phase so that the weight ratio of the oil phase becomes a predetermined weight percentage), and 16,000 with a homogenizer. The rotation was stirred for 5 minutes and emulsified.

[Measurement]
(1) Measurement of mixed bilayer film thickness (d-spacing) The mass of food emulsifier is used to examine the change in the long-face distance (001 plane, d-spacing) of phospholipid bilayers by the addition of food emulsifier and oil The mixed liquid crystal dispersion having the changed composition Ws and the emulsion having the changed oil concentration were measured with a scattering powder X-ray diffractometer (RAD-rA; Rigaku Corporation). The dispersion or emulsion was taken in a glass cell exclusively for XRD measurement and measured so as not to be dried. The measurement conditions are: output 40KV 50mA, Cukα measurement angle 2θ = 0.2 to 5.0 °, scan speed 1.0 ° / min, scan step 0.002 °, divergence slit 1/2 deg, scattering slit 1/6 deg. The light receiving slit was 0.15 mm.
(2) Measurement of phase transition temperature of mixed bilayer membrane In order to investigate the change of gel liquid crystal transition temperature Tm of phospholipid bilayer membrane by addition of food emulsifier, the mass composition Ws of food emulsifier was changed, and differential scanning calorimetry (SEIKO; DSC6100) was performed. About 50 μl of a sample was taken in a sealed cell made of aluminum having a volume of 70 μl, accurately weighed and sealed. The reference sample used approximately the same amount of water as the measurement sample. The measurement conditions were a temperature rising process at a temperature rising rate of 2 ° C. min ⁻¹ in a range of −5 to 90 ° C.
(3) Measurement of particle diameter The particle diameter of the emulsifier and the emulsion was measured with a dynamic light scattering photometer (FPAR-1000; Otsuka Electronics). The dispersion was performed using a dilute probe and a concentrated probe for the emulsion. The measurement temperature was room temperature similar to the storage temperature.
(4) Turbidity measurement of dispersion
In order to investigate the turbidity change of the dispersion due to the addition of the food emulsifier, it was measured by ultraviolet / visible spectroscopy (Nikko spectroscopy; V-570U best). The dispersion was fixed at 0.5 wt% SLP, and UV-vis measurement conditions were fixed at a wavelength of 480 nm, and the absorbance was measured.
(5) Shape observation of mixed liquid crystal In order to investigate the shape of the emulsifier bilayer, it was observed with a transmission electron microscope (JEOL; JEM-2000EX / FXII) using a negative staining method. The dispersion was dropped onto a Cu mesh with a support film, dried, and then ammonium molybdate was dropped and dried for 1 day, set on a TEM and observed. By using the negative staining method, the organic matter structure, which is usually difficult to observe due to the low electron density, is surrounded by an unstructured and high electron density molecular compound (ammonium molybdate), and the sample is placed between the sample and the support membrane. Add contrast and observe the structure and shape of the tissue.
(6) Stability of emulsion The stability of the prepared emulsion was visually observed by a stationary method. The mixture was allowed to stand at room temperature so as not to apply external force such as shaking and stirring. Changes over time were observed with a digital camera.

[Emulsification with DMPC-C ₁₄ (EO) ₈ ]
Common surfactants form micelles and liquid crystals. It is known that long-chain alkanes are adsorbed and solubilized by surfactant micelles and hydrophobic groups of lamellar liquid crystals. Furthermore, when an alkane is added excessively, the alkane more than saturation solubilization will form an oil droplet. At this time, the surfactant forms an emulsion by orienting the hydrophilic group to the aqueous phase and the hydrophobic group to the oil droplet phase. However, DMPC-C ₁₄ (EO) ₈ composed of a mixed liquid crystal obtained by adding a surfactant to a phospholipid bilayer membrane used this time is composed of an oil phase, an emulsifier phase, and an aqueous phase due to an excess oil agent. Forms a three-phase structure and exhibits excellent stability at low concentrations. Furthermore, it has been reported that phospholipid lamellar liquid crystals exhibit a similar emulsification tendency even when oil agents such as hexadecane and octadecane are changed. Therefore, in order to examine whether these findings about the three-phase emulsification mechanism and stability are also applicable to the emulsification of soybean oil, the emulsifiability was investigated using saturated oil and unsaturated oil.

[Three-phase emulsification mechanism and stability]
FIG. 1 shows the emulsion and particle size of DMPC-C ₁₄ (EO) ₈ and hexadecane. Expressing the molar fraction of the hexadecane to phospholipid used as emulsifier as X _H, hexadecane at X _H ≦ 0.5 is solubilized in DMPC-C ₁₄ (EO) ₈ mixed crystal layer, becomes saturated solubilization state . When X _H > 0.5, hexadecane becomes excess oil and DMPC-C ₁₄ (EO) ₈ vesicle particles adhere to the surface of hexadecane oil droplets to form a three-phase emulsion consisting of an oil phase, an emulsifier phase, and an aqueous phase. It is considered. DMPC-C ₁₄ (EO) ₈ and hexadecane emulsions become cloudy when X _H ≦ 0.5 due to the three-phase emulsification mechanism, but become transparent when X _H > 0.5 and form an emulsion of very small particles. It has been reported.
Oils commonly used in food are natural vegetable oils that contain many mixtures. These are three-chain unsaturated oils. Therefore, it was investigated whether triolein was used to show a three-phase emulsification mechanism like hexadecane.

[Effect of oil]
FIG. 2 shows the emulsion and particle size of triolein with DMPC-C ₁₄ (EO) ₈ . Expressing the molar fraction of triolein to phospholipid as _{X 0,} triolein with X 0 <0.7 is solubilized in DMPC-C ₁₄ (EO) ₈ mixed crystal layer, becomes saturated solubilization conditions. When X ₀ > 0.7, it was revealed that DMPC-C ₁₄ (EO) ₈ single particles due to excess oil form a three-phase emulsion that adheres to the surface of the oil droplets.
The emulsion of triolein also forms a stable emulsion by the three-phase emulsification method like hexadecane, and the appearance becomes cloudy with X ₀ <0.7 and X ₀ > 0.8, but pale interference with X ₀ = 0.7 Light appeared, and the particle size became very small with 10 nm or less.
Unlike hexadecane, triolein had an emulsion particle size of X ₀ <0.7, the light scattering increased, and the appearance was turbid. However, very small particles were formed in a saturated solubilized state, and a nanoemulsion that was as stable as hexadecane could be prepared.

[Phospholipids-Preparation of edible emulsifiers using food emulsifiers]
From the above, it has been clarified that the mixed emulsifier of phospholipid-surfactant can prepare a stable nanoemulsion regardless of the type of oil. Therefore, an edible emulsifier was used instead of a surfactant to form a mixed membrane vesicle of phospholipid and food emulsifier, and an attempt was made to prepare a dispersion that can be used as a transparent nano-sized emulsifier.

[Determination of food emulsifier to be added]
The phospholipid SLP to be used formed 363 nm vesicles in water from DLS and TEM observation, and the appearance was yellow. Therefore, in order to prepare transparent and nano-sized dispersions, we examined suitable additives from food emulsifiers approved by the Ministry of Health and Welfare.
Currently, five types of food emulsions are recognized: fatty acid glycerin ester, fatty acid propylene glycol ester, fatty acid sorbitan ester, fatty acid sucrose ester, and soybean phospholipid. Table 2 shows the physical properties of the food emulsifiers used this time.

FIG. 3 shows the appearance of the SLP-food emulsifier mixed system. The appearance of the dispersion varied depending on the type of food emulsifier. The glycerin ester did not change in appearance, and the sorbitan ester increased in turbidity. However, in the SLP-MSE system, the appearance changed significantly between Ws = 0.6 and Ws = 0.7, and it became transparent. MSE has the highest hydrophilicity compared to other emulsifiers, and is completely dissolved in water, so it is considered that compatibility with the SLP bilayer increases. Therefore, when preparing a transparent nanoemulsion, it was decided to use MSE as a food emulsifier.

[Examination of physical properties of SLP-MSE mixed membrane dispersion]
(XRD measurement results)
FIG. 4 shows the results of measuring the X-ray intensity of the SLP-MSE mixed system while changing the mass fraction (Ws) of MSE. FIG. 5 shows the mass fraction (Ws) of MSE in the emulsifier and the SLP. The relationship of bimolecular film thickness is shown. The bilayer thickness of SLP decreased continuously to Ws = 0.7, became discontinuous when 0.7 <Ws <0.8, and the peak was broken into two when Ws = 0.8. Thus, the reason why the film thickness d varies depending on the film composition is considered as follows. That is, MSE is solubilized in the bilayer membrane of phospholipid, and a space is generated due to the difference in chain length of the hydrophobic group, and d-spacing is considered to decrease from about 5.3 nm to about 4.3 nm due to the action of intermolecular force. It was. After that, the mixed film forms a saturated mixed crystal at Ws = 0.7, the particle diameter becomes almost constant 100 nm, MSE is excessively present at Ws> 0.7, and the bilayer film that cannot be maintained is When Ws = 0.8, two film states were obtained, and respective peaks were given.
(DLS measurement result)
FIG. 6 shows the relationship between the mass fraction (Ws) of MSE in the emulsifier and the particle diameter of the dispersion. The particle diameter decreased from 363 nm to 99.0 nm when Ws <0.6 with the addition amount of MSE, and two peaks were observed when Ws> 0.7. It was found that the solubilization of MSE in the bilayer film formed a mixed film vesicle with small particles due to the change in the structure of the film. The particle diameter of Ws ≧ 0.7 is measured by the dynamic light scattering method. As a result, the two peaks are about 4 nm and about 100 nm. Therefore, it is considered that a part of the vesicle changes to a rod shape.
From the above, the SLP-MSE dispersion has a mixed vesicle when Ws ≦ 0.6 and a mixed film lamellar liquid crystal when 0.6 <Ws ≦ 0.7 because the SLP bilayer is maintained when Ws ≦ 0.7. Was confirmed to form.
(TEM observation)
Furthermore, in order to observe the dispersion particles, FIGS. 7 to 10 show TEM photographs. The dispersion of SLP alone confirmed 363 nm particles by DLS measurement, but TEM observation revealed that vesicles having a distribution in size were formed. By adding MSE, vesicles based on SLP were confirmed when Ws ≦ 0.5, and vesicles and lamellar liquid crystals were formed when 0.5 <Ws ≦ 0.7, and lamellar liquid crystals were formed when Ws> 0.7. . Since the hydrophilic base of MSE is larger than SLP, the hydrophilic base cannot enter the bilayer membrane. On the other hand, SLP forms a multi-layer, and when MSE is added, the outer membrane has a close-packed structure first, and when further added, the particles are subdivided to increase the surface area and form small vesicles. It is considered that when the SLP film is saturated, the curvature cannot be maintained and a rod-like lamellar liquid crystal is formed.
(Turbidity and appearance)
FIG. 11 shows the relationship between the mass percent composition and turbidity. Since MSE was dissolved in water alone, the dispersion concentration of SLP in water was always kept constant at 0.5 wt%, and turbidity measurement was performed at a fixed wavelength of 480 nm. The turbidity of the dispersion decreased significantly when 0.4 <Ws <0.7 and became constant when Ws ≧ 0.7. From the TEM photograph, the turbidity is considered to be derived from SLP because it matches the region where the shape of the mixed film vesicle changes to the mixed film lamella liquid crystal.
From the above, it was found that the addition of MSE causes a structural change in the SLP bilayer film, the mixed film vesicles are subdivided, and when further added, a mixed film lamellar liquid crystal is formed. As a result, as shown in FIG. 12, a dispersion liquid forming nano-sized particles by transparent SLP-MSE could be prepared.

[Examination of three-phase emulsification]
An attempt was made to create an edible emulsion by the three-phase emulsification method using the dispersion prepared above. The dispersions used were SLP 0.5 wt% having different shapes, Ws = 0.5 vesicle region, Ws = 0.6 vesicle and lamellar liquid crystal region, and Ws = 0.7 lamella region.
Tables 3 and 4 show, for comparison, an example of emulsification of soybean oil using an SLP-only system when the emulsification temperature is set to room temperature and 50 ° C. In Tables 5 to 7, emulsification examples of soybean oil by the SLP-MSE mixed system are as follows: vesicle region of Ws = 0.5, vesicle and lamellar liquid crystal region of Ws = 0.6, lamella of Ws = 0.7 In each of the areas, the case where the emulsification temperature is set to room temperature is shown.

13-17 shows the stability of the emulsion by a stationary method with the external appearance of an emulsion. In the SLP alone system, the oil was separated from the oily phase 3 days after preparation. However, in the emulsion using the SLP-MSE mixed film liquid crystal, coacervation occurred in 1 day, and a stable oil emulsion was maintained even after 120 days without a free oil phase.

  Even under coacervation, the emulsifier nanoparticles adhere stably to the oil droplet interface in the three-phase emulsification method, so there is a distance between the oil droplets in the emulsion, and intermolecular force does not work between the oil droplets, Coalescence hardly occurs and the emulsion exists stably. Therefore, the emulsion prepared with the SLP-MSE mixed liquid crystal was stably maintained in the emulsion state for 120 days after the occurrence of the coacervation phenomenon by the three-phase emulsification method. The reason why the mixed liquid crystal of SLP-MSE becomes more stable than SLP alone is thought to be because the cohesive force of the molecules in the bilayer film becomes stronger due to the coexistence of MSE, and the film becomes hydrophobic and stabilized.

In the emulsion with a general surfactant, when the amount of oil increases, the liquid crystal peak of the liquid crystal formed by the surfactant disappears because the liquid crystal of the surfactant has the hydrophobic groups aligned in the oil droplets. However, it has been reported that the emulsion by the three-phase emulsification method maintains the liquid crystal peak in the bilayer film even after the addition of oil. Therefore, in order to confirm that the emulsion by SLP-MSE forms a three-phase structure, the results of XRD measurement of Ws = 0.5, Ws = 0.6, Ws = 0.7 are shown in FIGS. Indicated. The bilayer thickness of the SLP-MSE mixed film liquid crystal is Ws = 0.5 and 4.52 nm is 4.55 nm in the emulsion, Ws = 0.6 and 4.37 nm is 4.72 nm in the emulsion, and Ws = 0. 7 changed 4.26 nm to 4.33 nm in the emulsion. Since the bilayer thickness of the emulsion was slightly wider than that of the dispersion, the oil was solubilized in the bilayer membrane, and it was confirmed that the liquid crystal bilayer membrane was maintained after the oil was added. . FIG. 21 shows the relationship between oil concentration and SLP-MSE mixed liquid crystal film thickness using an emulsion of SLP-MSE with Ws = 0.6. The SLP-MSE mixed liquid crystal film thickness of the dispersion is about 4.3 nm, and gradually spreads as oil is added, and becomes about 4.5 nm after 10 wt%. Thereafter, there was no change in the emulsion state despite the increase in the oil component.
As a result, the three-phase emulsification method using SLP-MSE mixed liquid crystal has succeeded in creating an edible emulsion that is easier to prepare and more stable than conventional emulsification techniques using surfactants.

[Difference of emulsion due to shape change of dispersion]
As described above, it was confirmed that the shape of the dispersion was different depending on the mixing ratio of SLP-MSE. In order to investigate whether this change in shape affects the stability of the emulsion or the emulsification method, particle size measurement was performed. Went.
FIG. 22 shows changes in oil concentration and particle size due to differences in the shape of the dispersion. In the vesicle region where Ws = 0.5, the particle diameter increased after 40 wt%. The lamellar region with Ws = 0.6 was constant at about 200 nm, and the lamellar region with Ws = 0.7 was discontinuous. For this reason, it was suggested that it may depend on the shape of the dispersion.

[Phospholipids-Stability of edible emulsions with food emulsifiers]
General surfactants have different stability depending on oil, pH and temperature. Therefore, in order to examine the stability of the edible emulsion by SLP-MSE created as described above, the oil, pH, and storage temperature were changed. 23 to 25 show the stability of the emulsion method by the appearance of the emulsion. In addition to soybean oil that has been studied so far, olive oil, rice bran oil, vegetable oil such as rapeseed oil, and other common oils such as liquid paraffin, oily functional substances tocopherol (vitamin E), and limonene were emulsified.
Table 8 shows the results. All oils were coacervated and then stable for 150 days. As for the pH change, the stability was examined at pH 5 or less used in foods. Similar to the emulsion without additives, it was stable for 150 days.

  The temperature change was performed at −20 ° C., room temperature, and 50 ° C. Those stored at 50 ° C. had oil agglomeration after 30 days. FIGS. 26 and 27 show the results of XRD measurement for examining changes in the SLP-MSE mixed liquid crystal film. As shown in FIG. 27, at 30 days, the system stored at 50 ° C. had three peaks. This is presumably because the peak derived from the SLP-MSE mixed liquid crystal film was divided into two peaks derived from SLP and an MSE peak. That is, it shows that oil aggregation occurred because the mixed liquid crystal film was broken, and it can be assumed that the stability of the emulsion essentially depends on the stability of the SLP-MSE mixed liquid crystal film.

[Stability of diluted emulsion]
Food emulsifiers are required to form stable emulsions at low concentrations. Therefore, we examined whether to dilute the edible emulsion created in this study to form a stable emulsion with a low concentration of emulsifier.
FIG. 28 shows the results of diluting the emulsion created in FIG. 16 10 times and observing the particle size and appearance. The particle size was constant at about 200 nm in all concentrations, and was almost the same as the emulsion before dilution, forming a stable emulsion. In general surfactants, when diluted with water, surfactant molecules adsorbed on the surface of the oil droplets are released due to a decrease in the surfactant concentration in the aqueous solution, so that the oil is separated. However, since the edible emulsion created by the three-phase emulsification method emulsifies oil by adhering fine particles, the oil droplets and the emulsifier phase are stably dispersed in water. Therefore, the dilution did not affect the stability, and a low-concentration translucent edible emulsion could be created.

[Stability due to difference in carbon chain length of fatty acid ester]
Although the above-mentioned sucrose fatty acid ester showed the example in case carbon chain length is 14, Table 9 shows the result emulsified using sucrose fatty acid ester from which carbon chain length differs. Different carbon chain lengths did not affect stability, and a stable emulsion could be formed.

[Stability by type of lecithin]
In the above description, an example using soybean lecithin (SLP) was shown, but Table 10 shows an example of emulsification of soybean oil by a mixed system of egg yolk lecithin and sucrose myristic acid ester. A stable emulsion could be formed even in egg yolk lecithin.

[Stability of edible emulsions depending on the type of emulsifier for food]
In the above, the case where sucrose fatty acid ester is used as a food emulsifier to be mixed with soybean lecithin (SLP) has been shown, but the food emulsifier (fatty acid ester species) to be mixed with soybean lecithin (SLP) is made different so that the soybean oil An example of emulsification is shown in Table 11. In any food emulsifier, a stable edible emulsion could be formed.

  In the above, an example has been shown in which an edible emulsion is formed using an emulsifying dispersant containing a mixed liquid crystal in which a phospholipid and a fatty acid ester are mixed as a main component, but instead of the mixed liquid crystal described above, starch is used. It was possible to form a stable edible emulsion even when emulsified with a sugar polymer such as or chitosan. Table 12 shows emulsification examples of soybean oil, rapeseed oil, olive oil and rice squeeze oil by starch, and Table 13 shows emulsification examples of soybean oil by chitosan.

[Conclusion]
As described above, a stable emulsion of edible vegetable oil has been difficult to prepare conventionally, but the following results could be obtained by this method.
1. By making soy lecithin and fatty acid ester into a mixed liquid crystal, an excellent fine particle emulsifier could be obtained.
2. The mixed liquid crystal fine particle emulsifier was able to stably emulsify edible vegetable oil up to 90 wt% of the oil component.
3. The prepared edible emulsion has a three-phase emulsion structure.
4). The emulsion prepared with soybean oil becomes a translucent emulsion having a size of about 150 nm, and a new practical application of the emulsification technique is expected.

FIG. 1 is a diagram showing the emulsion and particle size of DMPC-C ₁₄ (EO) ₈ and hexadecane. FIG. 2 is a diagram showing the emulsion and particle diameter of triolein with DMPC-C ₁₄ (EO) ₈ . FIG. 3 is a photograph showing the appearance of the SLP-food emulsifier mixed system. FIG. 4 is a diagram showing the results of XRD measurement of a mixed SLP-MSE system by changing the mass fraction (Ws) of MSE. FIG. 5 is a graph showing the relationship between the mass fraction (Ws) of MSE in the emulsifier and the bilayer thickness of SLP. FIG. 6 is a graph showing the relationship between the mass fraction (Ws) of MSE in the emulsifier and the particle diameter of the dispersion. FIG. 7 is a TEM photograph observing the dispersion particles. FIG. 8 is a TEM photograph observing the dispersion particles. FIG. 9 is a TEM photograph observing the dispersion particles. FIG. 10 is a TEM photograph in which the dispersion particles are observed. FIG. 11 is a diagram showing the relationship between the mass percent composition and turbidity. FIG. 12 is a photograph of the SLP-MSE mixed system observed with the mass fraction (Ws) of SLP and MSE changed. FIG. 13 is a photograph showing the stability of the emulsion by the standing method in the appearance of the emulsion. FIG. 14 is a photograph showing the stability of the emulsion by the standing method as the appearance of the emulsion. FIG. 15 is a photograph showing the stability of the emulsion by the standing method as the appearance of the emulsion. FIG. 16 is a photograph showing the stability of the emulsion by the standing method as the appearance of the emulsion. FIG. 17 is a photograph showing the stability of the emulsion by the standing method as the appearance of the emulsion. FIG. 18 is a diagram showing the results of XRD measurement when the mass fraction (Ws) between SLP and MSE is 0.5. FIG. 19 is a diagram showing the results of XRD measurement when the mass fraction (Ws) between SLP and MSE is 0.6. FIG. 20 is a diagram showing the results of XRD measurement when the mass fraction (Ws) between SLP and MSE is 0.7. FIG. 21 is a diagram showing the relationship between the oil concentration and the SLP-MSE mixed liquid crystal film thickness when an emulsion of SLP-MSE with Ws = 0.6 is used. FIG. 22 is a diagram showing changes in oil concentration and particle size due to differences in the shape of the dispersion. FIG. 23 is a photograph showing the stability of the emulsion by the standing method in the appearance of the emulsion. FIG. 24 is a photograph showing the stability of the emulsion by the standing method in the appearance of the emulsion. FIG. 25 is a photograph showing the stability of the emulsion by the standing method with the appearance of the emulsion. FIG. 26 is a diagram showing the result of XRD measurement for examining the SLP-MSE mixed liquid crystal film change. FIG. 27 is a diagram showing the results of XRD measurement on the 30th day. FIG. 28 is a diagram showing the results of diluting the emulsion created in FIG. 16 ten times and observing the particle size and appearance.

Claims (7)

An edible emulsion comprising, as an essential component, an emulsifying dispersant mainly composed of a mixed liquid crystal obtained by mixing phospholipid and fatty acid ester in edible oil. The edible emulsion according to claim 1, wherein the mixed liquid crystal is formed by mixing soybean phospholipid and a fatty acid ester. The fatty acid ester is a fatty acid sucrose ester, and the mass fraction of the soybean phospholipid and the fatty acid sucrose ester is M1, the mass of the soybean phospholipid is M1, the mass of the fatty acid sucrose ester is M2, and the mass fraction is Ws. 3 is M2 / (M1 + M2), the edible emulsion according to claim 2, wherein 0.1 ≦ Ws <0.8 is set. The weight ratio is composed of 0.05 to 20% of the phospholipid, 0.005 to 8.0% of the sugar ester, 10 to 90% of edible oil, and a water balance. Edible emulsion. The edible emulsion according to claim 1, wherein the edible oil is soybean oil, rice squeeze oil, olive oil, rapeseed oil, or a functional additive oil. The edible emulsion according to claim 2, wherein the fatty acid ester is glycerin fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, or propylene glycol fatty acid ester. A phospholipid and a fatty acid ester are mixed so as to have a predetermined mass fraction, and water is added and dispersed so that the weight ratio of the phospholipid is a predetermined weight percent. A method for producing an edible emulsion, characterized in that the emulsion is prepared so that the weight ratio thereof is a predetermined weight percent.