A xanthan gum - zein - based Pickering emulsion and its preparation method

Abstract

The present invention discloses a xanthan gum - zein - based Pickering emulsion and a preparation method thereof, belonging to the field of emulsion preparation. In the present invention, zein particles are used as the main stabilizer of the oil - in - water (O / W) Pickering emulsion, and xanthan gum is used to improve the stabilizing effect of zein particles on the Pickering emulsion, and finally a stable xanthan gum - zein - based Pickering emulsion system is prepared. The emulsion system of the present invention can maintain stability at room temperature, under thermal sterilization, and cooking conditions when the addition amount of zein - xanthan gum particles is 0.4 mg / mL and the oil - phase fraction is 50 - 60%, maintaining the viscoelastic solid characteristics of the emulsion, and has great application potential as a fat substitute.

Description

Technical Field

[0001] The present invention relates to a xanthan gum - zein - based Pickering emulsion and a preparation method thereof, belonging to the technical field of emulsion preparation. Background Art

[0002] With the continuous improvement of living standards, people's intake of fat is increasing, and problems such as overweight and obesity are becoming more and more prominent. At the same time, obesity caused by a high - fat diet can lead to disorders of the intestinal flora and the occurrence of various metabolic diseases, such as cardiovascular diseases, diabetes, cancer, etc. Reducing fat intake is an effective means to solve this problem. However, directly removing fat from food will seriously affect the taste, flavor and storage stability of food, and reduce consumers' acceptance of food. Therefore, developing fat substitutes that can mimic the sensory and functional properties of fat and avoid the health hazards brought by a high - fat diet is one of the food development technologies that have received much attention in recent years.

[0003] The oil - in - water (O / W) emulsion system is an important form of oil in food, which can better maintain the unique lubricating taste and flavor of oil, and is commonly found in foods such as cream, mayonnaise, emulsified meat products, etc. In the case where the aqueous phase is the continuous phase, the O / W emulsion can be used as a fat substitute to effectively reduce the intake of oil. Food - grade Pickering emulsion is an emulsion system stabilized by solid particles made of food - grade natural macromolecules, which has excellent stability and safety, and has important application value as a fat substitute that meets the requirements of clean label.

[0004] However, the low emulsification efficiency, high cost and poor processing stability of the currently reported food - grade O / W Pickering emulsion are the key problems that need to be overcome urgently for its industrialization.

[0005] Zein is the main component in the by-products of corn starch processing. It is rich in sources and has a low degree of high-value utilization, showing great application potential in the development of Pickering emulsions. For example, the literature (Dai L, Sun C, Wei Y, et al. Characterization of Pickering emulsion gels stabilized by zein / gum arabic complex colloidal nanoparticles [J] Food Hydrocolloids, 2018, 74, 239-248.) prepared O / W Pickering emulsions using zein / gum arabic nanocomposite particles. When the particle dosage was 1%, the emulsion was only relatively stable at an oil phase fraction of 70% and was difficult to withstand heat treatment at higher temperatures; the literature (Jiratthitikan Sriprablom, Manop Suphantharika. Influence of xanthan gum on properties and stability of oil-in-water Pickering emulsions stabilized by zein colloidal particles [J]. Journal of Food Measurement and Characterization, 2022, 16, 2772–2781.) and the literature (Chen H, Wang Q, Rao Z, et al. The linear / nonlinear rheological behaviors of Pickering emulsion stabilized by Zein and Xanthan gum: Effect of interfacial assembly strategies) added xanthan gum to the O / W Pickering emulsions stabilized by zein nanoparticles. A relatively stable emulsion could be obtained only when the contents of zein nanoparticles and xanthan gum in the emulsion reached at least 1% and 0.5% respectively, and it was difficult to withstand heat treatment at higher temperatures.

[0006] It can be seen that the conventional method of using zein to prepare oil-in-water emulsions requires a high content of zein nanoparticles and xanthan gum and cannot achieve stability at high temperatures. Therefore, there is still an urgent need for an efficient method for preparing O / W Pickering emulsions to achieve high stability of the emulsion under common food processing conditions such as thermal sterilization and cooking while reducing the dosage of nanoparticles.

[0007] Moreover, it is difficult to apply conventional emulsions as fat substitutes in high-temperature (cooking) environments. For example, CN 116806998 A can be applied to room-temperature 3D printing but cannot be used at high temperatures; the oil-in-water emulsion prepared by CN117099939A is only stable in the range of (-20 to 70 °C) and cannot be stabilized under cooking (100 °C). However, many conventional foods require high-temperature heating, such as sausages, grilled meats, zongzi, meat buns, etc. Therefore, it is very necessary to have a fat substitute suitable for high-temperature processing. When using a stable emulsion as a fat substitute, small-molecule gelling agents, emulsifiers, etc. are required, which are difficult to meet the requirements of a clean fat substitute, such as CN115349555B. Moreover, the addition of small-molecule gelling agents and emulsifiers will affect the taste and use of the fat substitute, and it is difficult to achieve a high proportion of substitution, such as CN116898010A. Therefore, there is still a need for an emulsion that is stable at high temperatures for preparing foods that are heated at high temperatures and does not require additional additives to affect the taste, etc. Summary of the Invention

[0008] [Technical Problem]

[0009] The emulsification effect and thermal processing stability of the O / W Pickering emulsion prepared from pure food-grade macromolecular particles are very poor and it is difficult to be used as a fat substitute for heat treatment (such as cooking).

[0010] Conventional emulsions used for fat substitutes need to add emulsifiers, gelling agents, etc., and it is difficult to meet the taste and use requirements when the substitution ratio is very high.

[0011] [Technical Solution]

[0012] To solve the above problems, the present invention provides a xanthan gum - zein-based Pickering emulsion and a preparation method thereof. Specifically, the present invention uses zein particles as the main stabilizer of the oil-in-water (O / W) Pickering emulsion, and uses xanthan gum to improve the emulsification efficiency of zein nanoparticles and improve their thermal stability effect on the Pickering emulsion, and finally prepares a stable xanthan gum (XG) - zein-based Pickering emulsion system. The emulsion system of the present invention can remain stable at room temperature, thermal sterilization, and cooking conditions when the addition amount of zein-xanthan gum particles is as low as 0.4 mg / mL and the oil phase fraction is 50 - 60%, maintaining the viscoelastic solid characteristics of the emulsion, and has great application potential as a fat substitute.

[0013] The first object of the present invention is to provide a method for preparing a xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion with good stability at room temperature, thermal sterilization, and cooking conditions, including the following steps:

[0014] (1) Drop the zein solution into the xanthan gum solution to obtain a zein-xanthan gum particle dispersion; then dry it to obtain zein-xanthan gum particles.

[0015] (2) Disperse the zein-xanthan gum particles in water as the aqueous phase, mix the aqueous phase and the oil phase, and perform high-speed shearing to obtain a xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion; wherein, the oil phase is medium-chain triglyceride or vegetable oil.

[0016] In one embodiment of the present invention, the concentration of the zein solution in step (1) is 10-60 mg / mL; specifically, zein is placed in an ethanol aqueous solution of 70-80% (v / v), and stirred at 300-1000 rpm for 30-100 min until the zein is fully dissolved.

[0017] In one embodiment of the present invention, the concentration of the xanthan gum solution in step (1) is 1-3 mg / mL; specifically, it is obtained by dissolving xanthan gum in water.

[0018] In one embodiment of the present invention, the dropping rate in step (1) is 0.5-1.5 mL / min.

[0019] In one embodiment of the present invention, the mass ratio of xanthan gum in the xanthan gum solution to zein in the zein solution in step (1) is 0.6:1-1:1.

[0020] In one embodiment of the present invention, the vegetable oil in step (2) includes one or more of peanut oil, soybean oil, corn oil, and rapeseed oil.

[0021] In one embodiment of the present invention, the concentration of the zein-xanthan gum particles in the aqueous phase in step (2) is 4-10 mg / mL.

[0022] In one embodiment of the present invention, the volume ratio of the oil phase to the aqueous phase in step (2) is 5:5-6:4.

[0023] In one embodiment of the present invention, the high-speed shearing in step (2) is performed at 10000-14000 rpm for 2-5 min.

[0024] The second object of the present invention is the xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion prepared by the method of the present invention.

[0025] The third object of the present invention is the application of the xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion of the present invention in the food field.

[0026] In one embodiment of the present invention, the foods include ice cream, salad dressing, mayonnaise, sausage, honey-roasted chicken strips, low-sugar and low-fat imitation cheese, etc.

[0027] The fourth object of the present invention is to provide a fat substitute that can be used at room temperature, for thermal sterilization, and for steaming processing, which uses xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion.

[0028] In one embodiment of the present invention, the xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion in the fat substitute can replace up to 75% by proportion.

[0029] The fifth object of the present invention is to provide a sausage that uses xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion.

[0030] In one embodiment of the present invention, the sausage is prepared by the following method:

[0031] Add pig fat mince and xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion as an animal fat substitute to pig lean meat mince, and then add sodium chloride solution, and stir to mix well;

[0032] Fill it into a plastic casing and seal it, steam it, and remove the plastic casing after cooling to room temperature to obtain the sausage;

[0033] Among them, the mass ratio of pig lean meat mince, pig fat mince, and xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion is 20:2 - 5:4 - 7;

[0034] The sodium chloride solution is an aqueous solution of sodium chloride, and the concentration is 0.5 - 1.5%;

[0035] The mass ratio of pig lean meat mince to sodium chloride solution is 20:0.2 - 0.4;

[0036] The steaming is carried out at 100°C for 10 minutes.

[0037] The sixth object of the present invention is to provide a method for improving the stability of oil-in-water Pickering emulsion under room temperature, thermal sterilization, and steaming conditions, which uses the xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion of the present invention.

[0038] [Beneficial effects]

[0039] (1)The present invention uses zein particles as the main stabilizer of the oil-in-water (O / W) Pickering emulsion, and xanthan gum is used to improve the stabilizing effect of zein particles on the Pickering emulsion, and finally a thermally stable xanthan gum-zein emulsion system is prepared. This emulsion system can still remain stable at room temperature, under thermal sterilization, and cooking conditions when the water content is as high as 50%, maintaining the viscoelastic solid characteristics of the emulsion, and has great application potential as a fat substitute.

[0040] (2)The xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion prepared by the present invention can be used as a fat substitute in thermally processed foods, such as: sausages, and the substitution ratio can be as high as more than 75%.

[0041] (3)The xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion of the present invention is pure food-grade, and no additional emulsifiers, gelling agents, etc. are required during the preparation process; it can also achieve the effect of being resistant to cooking; it can be used to prepare sausages, zongzi, etc., and has broad application prospects.

[0042] (4)The xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion of the present invention can remain stable at room temperature, under thermal sterilization, and cooking conditions when the addition amount of zein-xanthan gum particles is 0.4 mg / mL and the oil phase fraction is 50-60%, maintaining the viscoelastic solid characteristics of the emulsion, and has great application potential as a fat substitute. Description of the Drawings

[0043] Figure 1 SEM images of the nanoparticles in Examples 1, 2 and Comparative Examples 1, 3.

[0044] Figure 2 Surface potential test results of Examples 1, 2 and Comparative Examples 1, 3.

[0045] Figure 3 Emulsion stability test results of Examples 1, 2, 3, 4, 5 and Comparative Examples 1, 3, 4.

[0046] Figure 4 Rheological properties of the emulsions prepared in Examples 1-5.

[0047] Figure 5 States of the oil-water mixture after heat treatment in Comparative Example 2 and Comparative Example 5.

[0048] Figure 6 Fluorescent staining images of the emulsions prepared in Examples 1-5, where the gray is the oil phase and the black is the water phase. Detailed Description of the Invention

[0049] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0050] The raw materials used in the embodiments and comparative examples are:

[0051] Zein: water content ≤8%, purchased from Sigma-Aldrich;

[0052] Xanthan gum: USP grade, purchased from Aladdin;

[0053] Medium chain triglycerides (MCT): chain length 8-10 carbons; purchased from Jarrow, USA.

[0054] Test method:

[0055] 1. SEM test:

[0056] The sample to be tested was adhered to a conductive tape, and its surface was sprayed with gold. Its microstructure was observed by field emission scanning electron microscopy at an accelerating voltage of 5 kV.

[0057] 2. Surface potential test:

[0058] A dispersion of the sample to be tested was prepared with a concentration of 0.005%, and the particle surface potential was measured using a Malvern potential analyzer.

[0059] 3. Emulsion stability test:

[0060] After the emulsion was left to stand at room temperature for 24 hours, the stratification and demulsification of the emulsion were observed.

[0061] 4. Test of rheological properties:

[0062] The viscosity, storage modulus and loss modulus of the emulsion were measured by rheological analyzer, and the changes of viscoelasticity of the emulsion at different treatment temperatures (room temperature, 65°C, 100°C) were analyzed.

[0063] 5. Fluorescence microscope test:

[0064] The water phase in the emulsion is stained with fast green, and then a fluorescence microscope is used to observe whether the emulsion is an O / W emulsion or an O / W emulsion. In the microscope image of the stained emulsion, the oil phase appears gray and the water phase appears black.

[0065] 6. Texture test:

[0066] The sausages prepared with fat replacers were cut into cylinders with a height of 1 cm and their hardness, viscoelasticity, elasticity, chewiness and cohesion were measured using a texture analyzer.

[0067] 7. Stability test:

[0068] After storing the prepared emulsion at room temperature (20 - 30 °C) for 2 weeks, observe the layering of the emulsion.

[0069] 8. Sensory test:

[0070] Cut the sausage prepared with the fat substitute into cylinders with a height of 1 cm, and evaluate the sensory properties by 8 trained volunteers.

[0071] For sensory evaluation, the evaluation criteria are as shown in Table 1 below:

[0072] Table 1

[0073]

[0074] Example 1

[0075] A method for preparing a xanthan gum - zein - based oil - in - water (O / W) Pickering emulsion, comprising the following steps:

[0076] (1) Place zein in an 80% (v / v) ethanol aqueous solution, stir at 500 rpm for 30 min until zein is fully dissolved to obtain a zein solution with a concentration of 40 mg / mL; dissolve xanthan gum in water to obtain a xanthan gum solution with a concentration of 2 mg / mL;

[0077] At a stirring speed of 500 rpm, drop the zein solution into the xanthan gum solution at a rate of 1 mL / min, such that the mass ratio of xanthan gum to zein is 0.6:1 to obtain a zein - xanthan gum particle dispersion; then dry to obtain zein - xanthan gum particles (zein - xanthan gum nanoparticles);

[0078] (2) Disperse the zein - xanthan gum particles in water as the aqueous phase, and medium - chain triglyceride as the oil phase. Mix the oil phase and the aqueous phase at a volume ratio of 6:4, such that the total concentration of zein - xanthan gum particles in the oil - water two - phase is 4 mg / mL, and perform high - speed shearing at 12000 rpm for 2 min to obtain a xanthan gum - zein - based oil - in - water (O / W) Pickering emulsion.

[0079] Example 2

[0080] Adjust the mass ratio of xanthan gum to zein in step (1) of Example 1 to 0.8:1, and keep the others the same as in Example 1 to obtain a xanthan gum - zein - based oil - in - water (O / W) Pickering emulsion.

[0081] Example 3

[0082] Adjust the medium-chain triglyceride (MCT) in step (2) of Example 1 to corn oil, and keep the others the same as in Example 1 to obtain a xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion.

[0083] Example 4

[0084] Adjust the volume ratio of the oil phase to the water phase in step (2) of Example 1 to 5:5, and keep the others the same as in Example 1 to obtain a xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion.

[0085] Example 5

[0086] Adjust the total concentration of zein - xanthan gum particles in the oil and water phases in step (2) of Example 1 to 6 mg / mL, and keep the others the same as in Example 1 to obtain a xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion.

[0087] Comparative Example 1

[0088] Omit the xanthan gum solution in step (1) of Example 1, and keep the others the same as in Example 1;

[0089] Specifically as follows:

[0090] (1) Place zein in an 80% (v / v) ethanol aqueous solution, stir at 500 rpm for 30 min until zein is fully dissolved to obtain a zein solution with a concentration of 40 mg / mL;

[0091] At a stirring speed of 500 rpm, drop the zein solution into water at a rate of 1 mL / min to obtain a zein particle dispersion; then dry to obtain zein particles;

[0092] (2) Disperse zein particles in water as the water phase, and medium-chain triglyceride as the oil phase. Mix the oil phase and the water phase at a volume ratio of 6:4 to make the total concentration of zein particles in the oil and water phases 4 mg / mL, and perform high-speed shearing at 12000 rpm for 2 min to obtain a zein-based oil-in-water (O / W) Pickering emulsion.

[0093] Comparative Example 2

[0094] Omit the zein solution in step (1) of Example 1, and keep the others the same as in Example 1;

[0095] Specifically as follows:

[0096] (1) Dissolve xanthan gum in water to obtain a xanthan gum solution with a concentration of 2 mg / mL;

[0097] (2) Using xanthan gum solution as the aqueous phase and medium-chain triglyceride as the oil phase, mix the oil phase and the aqueous phase at a volume ratio of 6:4, and perform high-speed shearing at 12,000 rpm for 2 min to obtain an oil-water mixture.

[0098] It was found that: using xanthan gum solution alone could not form nanoparticles nor form an O / W emulsion.

[0099] Comparative Example 3

[0100] Adjust the mass ratio of xanthan gum to zein in step (1) of Example 1 to 0.2:1, and keep the others the same as in Example 1 to obtain a xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion.

[0101] Comparative Example 4

[0102] Adjust the volume ratio of the oil phase to the aqueous phase in step (2) of Example 1 to 7:3, and keep the others the same as in Example 1 to obtain a xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion.

[0103] Comparative Example 5

[0104] Adjust the total concentration of zein - xanthan gum particles in the oil and water phases in step (2) of Example 1 to 2 mg / mL, and keep the others the same as in Example 1 to obtain a xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion.

[0105] Perform performance tests on the emulsions obtained in Examples 1 - 5 and Comparative Examples 1 - 5, and the test results are as follows:

[0106] Figure 1 SEM images of the nanoparticles in Examples 1, 2 and Comparative Examples 1, 3. From Figure 1 It can be seen that: the zein - xanthan gum nanoparticles in Examples 1, 2 and Comparative Example 3 have a spherical morphology, and the particles are dispersed in the xanthan gum matrix structure; the zein nanoparticles in Comparative Example 1 have a spherical morphology, and the particles show serious aggregation; compared with the zein nanoparticles, the dispersibility of the zein - xanthan gum nanoparticles is significantly improved.

[0107] Figure 2 Surface potential test results of Examples 1, 2 and Comparative Examples 1, 3. From Figure 2It can be seen that: in Example 1, when the ratio of xanthan gum to zein was 0.6:1, the surface of zein-xanthan gum nanoparticles was negatively charged, and the net charge value was 53.23 mV; in Example 2, when the ratio of xanthan gum to zein was 0.8:1, the surface of zein-xanthan gum nanoparticles was negatively charged, and the net charge value was 57.23 mV; in Comparative Example 3, when the ratio of xanthan gum to zein was 0.2:1, the surface of zein-xanthan gum nanoparticles was negatively charged, and the net charge value was 51.30 mV; this shows that the introduction of xanthan gum effectively increased the electrostatic repulsion between particles, thereby preventing particle aggregation; in Comparative Example 1, the surface of zein nanoparticles was negatively charged, and the net charge value was 6.25 mV, and the electrostatic repulsion between particles was weak, unable to prevent particle aggregation.

[0108] Figure 3 Results of emulsion stability tests for Examples 1, 2, 3, 4, 5 and Comparative Examples 1, 3, 4. From Figure 3 It can be seen that: in Examples 1 and 2, zein-xanthan gum nanoparticles effectively improved the emulsifying effect of zein nanoparticles on O / W emulsions; in Example 3, the emulsion remained stable after changing the oil phase from MCT to corn oil; in Example 4, the emulsion remained stable after adjusting the volume ratio of the oil phase to the water phase from 6:4 to 5:5; in Example 5, the emulsion remained stable after increasing the addition amount of zein-xanthan gum nanoparticles from 0.4 mg / mL to 0.6 mg / mL; the emulsions prepared in Examples 1-5 still maintained good stability after storage at room temperature for 2 weeks, and no layering phenomenon was observed; in Comparative Example 1, due to severe aggregation of zein particles, it was unable to disperse evenly at the oil-water interface and exert its emulsifying effect; in Comparative Example 3, zein-xanthan gum nanoparticles effectively improved the emulsifying effect of zein nanoparticles on O / W emulsions at room temperature, however, this emulsion showed layering after heat treatment and was not suitable as a fat substitute in thermally processed foods; in Comparative Example 4, obvious oil phase precipitation was observed in the emulsion prepared with zein-xanthan gum nanoparticles at room temperature, indicating poor emulsion stability and not suitable for further application in foods.

[0109] Figure 4 Rheological properties of the emulsions prepared in Examples 1-5. From Figure 4It can be seen that: the storage modulus G' of the emulsions prepared in Examples 1-5 is greater than the loss modulus G" after being treated under the conditions of room temperature and 65°C pasteurization, indicating that the emulsions exhibit stable viscoelastic solid characteristics; after being treated under the condition of boiling at 100°C, the storage modulus G' of the emulsions prepared in Examples 2, 3, and 5 is greater than the loss modulus G", indicating that the emulsions still exhibit stable viscoelastic solid characteristics. For the emulsions prepared in Examples 1 and 4, the storage modulus G' and the loss modulus G" cross each other, indicating that the emulsions can still maintain partial viscoelastic solid characteristics. Therefore, the emulsions prepared in Examples 1-5 can all be used to replace semi-solid characteristic oils and fats such as animal oils and shortening in food processing.

[0110] Figure 5 Shows the states of the oil-water mixtures in Comparative Example 2 and Comparative Example 5 after heat treatment. Figure 5 It can be seen that: for the emulsion of Comparative Example 2, significant phase separation occurs in the mixture system at room temperature and after heat treatment, and it is not suitable to be used as a fat substitute; for Comparative Example 5, the emulsion does not delaminate after being treated at room temperature and under the condition of 65°C pasteurization, but the emulsion delaminates after being treated under the condition of boiling at 100°C, indicating that the emulsion is not suitable for replacing animal fats in food processing.

[0111] Figure 6 Is the fluorescence staining diagram of the emulsions prepared in Examples 1-5, where the gray color represents the oil phase and the black color represents the water phase. Figure 6 It can be seen that: the emulsions prepared in Examples 1-5 are indeed oil-in-water emulsions.

[0112] Comparative Example 6

[0113] Adjust the xanthan gum in Example 1 to gallic acid, and keep the others the same as in Example 1.

[0114] It was found that:

[0115] Gallic acid cannot improve the dispersibility of zein and cannot form a stable O / W emulsion.

[0116] Comparative Example 7

[0117] Adjust the zein in Example 1 to myofibrillar protein, and keep the others the same as in Example 1.

[0118] It was found that:

[0119] Xanthan gum and myofibrillar protein cannot form nanoparticles and cannot be used to prepare O / W emulsions.

[0120] Comparative Example 8

[0121] Adjust the volume ratio of the oil phase to the water phase in step (2) of Example 1 to 8:2, and keep the others the same as in Example 1.

[0122] It was found that:

[0123] The emulsion showed significant stratification at room temperature and could not form a stable O / W emulsion.

[0124] Comparative Example 9

[0125] The xanthan gum in Example 1 was adjusted to arabic gum, and the others were kept the same as in Example 1.

[0126] It was found that:

[0127] The prepared zein-arabic gum nanoparticles could not form a stable O / W emulsion.

[0128] Comparative Example 10

[0129] A method for preparing an emulsion, comprising the following steps:

[0130] Disperse 1.25 g of zein in 100 mL of water, adjust the pH value to 7, and magnetically stir at 600 r / min for 3 h to form a zein particle suspension;

[0131] Disperse 0.75 g of xanthan gum in 100 mL of water, and magnetically stir at 600 r / min for 3 h until completely dissolved to form a xanthan gum solution;

[0132] Mix 20 mL of the zein particle suspension with 20 mL of the xanthan gum solution, perform high-speed shearing at 8000 rpm for 1 min, then add 60 mL of corn oil, and perform high-speed shearing at 12000 rpm for 2 min.

[0133] It was found that:

[0134] This method could not form a stable O / W emulsion.

[0135] Comparative Example 11

[0136] A method for preparing xanthan gum - zein-based oil-in-water (O / W) Pickering emulsion, comprising the following steps:

[0137] Place zein in an 80% (v / v) ethanol aqueous solution, stir at 500 rpm for 30 min until the zein is fully dissolved to obtain a zein solution with a concentration of 40 mg / mL; at a stirring speed of 500 rpm, drop the zein solution into water at a rate of 1 mL / min to obtain a zein particle dispersion; then dry to obtain zein particles;

[0138] Disperse zein nanoparticles in water as the aqueous phase, and use medium-chain triglycerides as the oil phase. Mix the oil phase and the aqueous phase at a volume ratio of 6:2, and perform high-speed shearing at 12,000 rpm for 2 min to obtain a zein-based oil-in-water (O / W) Pickering emulsion;

[0139] Dissolve xanthan gum in water to obtain a xanthan gum solution with a concentration of 2 mg / mL;

[0140] Then add the xanthan gum aqueous solution to the zein-based oil-in-water (O / W) Pickering emulsion so that the final volume ratio of the oil phase to the aqueous phase is 6:4, the total concentration of zein particles in the oil and water phases is 4 mg / mL, and the mass ratio of xanthan gum to zein is 0.6:1. Perform high-speed shearing at 12,000 rpm for 2 min to obtain a xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion.

[0141] The results showed that:

[0142] It was impossible to form a stable O / W emulsion.

[0143] Comparative Example 12

[0144] A method for preparing a xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion, comprising the following steps:

[0145] Place zein in an 80% (v / v) ethanol aqueous solution and stir at 500 rpm for 30 min until the zein is fully dissolved to obtain a zein solution with a concentration of 40 mg / mL; at a stirring speed of 500 rpm, drop the zein solution into water at a rate of 1 mL / min to obtain a zein particle dispersion; then dry to obtain zein particles;

[0146] Dissolve xanthan gum in water to obtain a xanthan gum solution with a concentration of 2 mg / mL;

[0147] Use the xanthan gum solution as the aqueous phase and medium-chain triglycerides as the oil phase. Mix the oil phase and the aqueous phase at a volume ratio of 6:2 and perform high-speed shearing at 12,000 rpm for 2 min to obtain a xanthan gum-based oil-water mixture;

[0148] Then add zein nanoparticles to this mixed system so that the final volume ratio of the oil phase to the aqueous phase is 6:4, the total concentration of zein particles in the oil and water phases is 4 mg / mL, and the mass ratio of xanthan gum to zein is 0.6:1. Perform high-speed shearing at 12,000 rpm for 2 min to obtain a xanthan gum-zein-based oil-in-water (O / W) Pickering emulsion.

[0149] The results showed that:

[0150] A stable O / W emulsion cannot be formed.

[0151] Example 6

[0152] Use the xanthan gum - zein - based oil - in - water (O / W) Pickering emulsion prepared in Example 1 to prepare sausages;

[0153] The specific steps are as follows:

[0154] Add 4.5 g of minced pork fat and 4.5 g of the emulsion prepared in Example 1 as an animal fat substitute to 20 g of minced lean pork, and then add 0.3 g (1%) of sodium chloride solution, and stir for 1 min to fully mix;

[0155] Fill it into a plastic casing and seal it, take it out after steaming at 100 °C for 10 min, and remove the plastic casing after cooling to room temperature to obtain sausages.

[0156] Example 7

[0157] Adjust the minced pork fat in Example 6 to 2.25 g and the emulsion to 6.75 g, and keep the others the same as in Example 6 to obtain sausages.

[0158] Comparative Example 13

[0159] Adjust the lard in Example 6 to 0 g and the emulsion to 10 g, and keep the others the same as in Example 6 to obtain sausages.

[0160] Comparative Example 14

[0161] Adjust the lard in Example 6 to 10 g and the emulsion to 0 g, and keep the others the same as in Example 6 to obtain sausages.

[0162] Perform performance tests on the prepared sausages, and the test results are as follows:

[0163] Table 2

[0164]

[0165] As can be seen from Table 2: When the substitution ratio of the fat substitute for animal fat does not exceed 75%, the prepared meat sausages have little difference from the meat sausages conventionally prepared with animal fat and lean pork in terms of hardness, adhesiveness, and cohesiveness, but are slightly higher than the meat sausages prepared by the traditional method in terms of elasticity and chewiness; when completely using the emulsion developed by this technology to replace animal fat, the hardness, elasticity, and chewiness of the prepared meat sausages are significantly increased compared with the meat sausages prepared by the traditional method;

[0166] Table 3

[0167]

[0168] As can be seen from Table 3, when the emulsion is used to replace no more than 75% of animal fat, the prepared meat sausage has no peculiar smell or bad taste compared with the conventional meat sausage, and has better elasticity in taste; it shows that the xanthan gum - zein emulsion can be successfully used as an efficient fat substitute.

[0169] Example 8

[0170] Use the xanthan gum - zein - based oil - in - water (O / W) Pickering emulsion of Example 1 to prepare honey - roasted chicken strips. The specific steps are as follows:

[0171] (1) Grind the chicken breast, add auxiliary materials and stir evenly, and then marinate; among them, the auxiliary materials include a sugar substitute, seasonings and the emulsion prepared in Example 1 as a fat substitute, and the mass ratio of the three is 0.3:6:1.5; the sugar substitute is trehalose and xylitol with a mass ratio of 1:1; the seasonings are egg white, fish sauce, pepper, monosodium glutamate and glycerol with a mass ratio of 8:2:0.2:0.7:5;

[0172] (2) Shape the marinated chicken into chicken strips, and dry them at 75 °C for 16 h;

[0173] (3) Brush a layer of the auxiliary materials in step (1) on the surface of the dehydrated and dried chicken strips, and then bake them at 120 °C for 14 min to obtain honey - roasted chicken strips; among them, the mass ratio of the auxiliary materials to the chicken is 5.5:1.

[0174] The performance of the honey - roasted chicken strips is consistent with the texture and taste of the conventional chicken strips.

[0175] Example 9

[0176] Use the xanthan gum - zein - based oil - in - water (O / W) Pickering emulsion of Example 1 to prepare low - sugar and low - fat imitation cheese:

[0177] The imitation cheese is prepared from the following raw materials by weight percentage: based on 100 of the protein mixture, 5% of functional sugar alcohol, 5% of xanthan gum - zein - based oil - in - water (O / W) Pickering emulsion, 0.2% of transglutaminase, 2.5% of emulsifying salt, and 0.3% of compound stabilizer;

[0178] The preparation method is: mixing raw materials → adding water and emulsifying salt, mixing at room temperature for 1 min → adding compound stabilizer → heat treatment and continuous stirring (80 °C / 5 - 8 min) → homogenizing and melting the block to make the pH between 8.0 and 8.5 → adding acidulant → adjusting the pH to 5.4 - 6.0 → hot filling the mold → cooling → storage (-4 to 4 °C) → finished product.

[0179] The performance of the imitation cheese is consistent with the texture and taste of the conventional cheese.

[0180] In summary, the native gum-zein-based oil-in-water (O / W) Pickering emulsion prepared by the present invention can be used for processing at room temperature, thermal sterilization, and high-temperature environments.

[0181] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A method for improving the stability of an oil-in-water Pickering emulsion under room temperature, heat sterilization, and cooking conditions, characterized in that: The steps include: (1) dropping a zein solution into a xanthan gum solution to obtain a zein-xanthan gum particle dispersion; and then drying to obtain zein-xanthan gum particles; The concentration of the zein solution is 10-60 mg / mL, the concentration of the xanthan gum solution is 1-3 mg / mL; the mass ratio of xanthan gum in the xanthan gum solution to zein in the zein solution is 0.8:1-1:1; the dropping speed is 0.5-1.5 mL / min; (2) dispersing zein-xanthan gum particles in water as an aqueous phase, mixing the aqueous phase and the oil phase, and shearing at high speed to obtain a xanthan gum-zein based oil-in-water (O / W) Pickering emulsion; The oil phase is medium-chain triglycerides or vegetable oil, and the volume ratio of the oil phase to the water phase is 6:4; the total concentration of zein-xanthan gum particles in the oil and water phases is 4 mg / mL.

2. The method according to claim 1, characterized in that The zein solution in step (1) is obtained by placing zein in a 70-80% (v / v) ethanol aqueous solution and stirring at 300-1000 rpm for 30-100 min until the zein is fully dissolved.

3. The method according to claim 1, characterized in that The vegetable oil in step (2) includes one or more of peanut oil, soybean oil, corn oil and rapeseed oil.

4. The method according to claim 1, characterized in that: In step (2), the high-speed shearing is carried out at 10000-14000 rpm for 2-5 min.

5. A xanthan gum-zein based oil-in-water (O / W) Pickering emulsion prepared by the method according to any one of claims 1 to 4.

6. Application of the xanthan gum-zein based oil-in-water (O / W) Pickering emulsion according to claim 5 in the food field.

7. A fat substitute that can be used for room temperature, heat sterilization, and steaming processing, characterized in that: The xanthan gum-zein based oil-in-water (O / W) Pickering emulsion described in claim 5 is used.

8. A sausage, characterized in that: The xanthan gum-zein based oil-in-water (O / W) Pickering emulsion described in claim 5 is used.

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