阅读说明：本技术 一种水包油凝胶Pickering乳液及其制备方法和用途 (Oil-in-water gel Pickering emulsion and preparation method and application thereof ) 是由 齐文慧 张志胜 淑英 饶伟丽 梁铁强 王晗 杨清蕊 于 2021-09-08 设计创作，主要内容包括：本发明是本发明所述的一种水包油凝胶Pickering乳液及其制备工艺及用途,方法包括如下步骤：第一步：天然蜡/植物油混合溶液的制备；第二步：纳米纤维素悬浮液的制备；第三步：乳液的制备。一种水包油凝胶Pickering乳液的用途是作为脂溶性营养物质的包埋递送体系进行使用或作为香肠中动物脂肪替代物以降低动物脂肪含量并提高香肠的冻融稳定性进行使用。本发明工艺克服了水包油Pickering乳液冻融稳定性差这一技术问题,显著提高了乳液冻融稳定性；所述的水包油凝胶Pickering乳液用于包埋递送脂溶性营养物质不仅可以提高营养素的贮藏稳定性,可提高营养物质的生物利用率；用于替代香肠中动物脂肪,不仅可降低动物脂肪的含量,与水包油Pickering乳液相比可显著提高香肠的冻融稳定性。(The invention relates to an oil-in-water gel Pickering emulsion and a preparation process and application thereof, wherein the method comprises the following steps: the first step is as follows: preparing a mixed solution of natural wax/vegetable oil; the second step is that: preparing a nano cellulose suspension; the third step: and (4) preparing an emulsion. An oil-in-water gel Pickering emulsion is used as an embedded delivery system of fat-soluble nutrient substances or as an animal fat substitute in sausages to reduce the content of animal fat and improve the freeze-thaw stability of the sausages. The process provided by the invention overcomes the technical problem of poor freezing and thawing stability of the oil-in-water Pickering emulsion, and remarkably improves the freezing and thawing stability of the emulsion; the oil-in-water gel Pickering emulsion is used for embedding and delivering fat-soluble nutrient substances, so that the storage stability of nutrients can be improved, and the bioavailability of the nutrient substances can be improved; the product is used for replacing animal fat in the sausage, not only can reduce the content of the animal fat, but also can obviously improve the freeze-thaw stability of the sausage compared with the oil-in-water Pickering emulsion.)

1. A preparation method of an oil-in-water gel Pickering emulsion is characterized by comprising the following steps:

the first step is as follows: preparation of natural wax/vegetable oil mixed solution

1) Weighing natural wax by a balance, and then adding the natural wax into the vegetable oil according to the proportion of 1.5-20% w/v to obtain a natural wax-vegetable oil mixture;

2) heating the natural wax-vegetable oil mixture for 10-30 min on a magnetic stirrer platform with the rotating speed of 90-120 rpm and the temperature set to 130-160 ℃ to melt and uniformly disperse the natural wax in the vegetable oil to obtain a solution I;

the second step is that: preparation of nanocellulose suspensions

1) Preparing a nano-cellulose suspension solution with the concentration of 0.05-2.0%, adjusting the pH value of the nano-cellulose suspension solution to 4.0-8.0, adjusting the concentration of sodium chloride to 0.0-1.0 mol/L, and stirring the solution uniformly by using a magnetic stirrer;

2) heating the prepared nano-cellulose suspension in a water bath kettle at the temperature of 55-95 ℃ for 15-30 min to make the temperature of the nano-cellulose suspension reach 55-95 ℃ to obtain a solution II;

the third step: preparation of the emulsion

1) Mixing the solution I and the solution II according to a volume ratio of 1: 9-4: 6 to obtain a solution III, stirring the solution III for 1-3 min by using an emulsification homogenizer at a rotating speed of 8000-15000 rpm, and then placing the solution III in a water bath kettle with a water temperature of 55-95 ℃ for homogenization by using a high-intensity ultrasonic processor, wherein the ultrasonic homogenization conditions are as follows: the amplitude pressure is 55-80%, and the time is 1.5-3.0 min (opening for 3 s/closing for 3s), so as to obtain a solution IV;

2) and immediately putting the obtained solution IV into an ice water bath for cooling for 10-30 min to obtain the oil-in-water gel Pickering emulsion.

2. The method of claim 1, wherein the vegetable oil is one of soybean oil, sunflower oil, rapeseed oil, peanut oil, olive oil, and almond oil.

3. The method for preparing the oil-in-water gel Pickering emulsion according to claim 2, wherein the nanocellulose is one of nanocellulose crystals, nanocellulose fibers, bacterial nanocellulose and modified nanocellulose.

4. The method for preparing the oil-in-water gel Pickering emulsion as claimed in claim 3, wherein the modified nanocellulose is one of acetylated nanocellulose, TEMPO oxidized bacterial cellulose and type II nanocrystalline cellulose ester.

5. The method for preparing the oil-in-water gel Pickering emulsion according to claim 1, wherein the natural wax is one of beeswax, spermaceti wax, Chinese insect wax, rice bran wax, carnauba wax, sugar cane wax, candelilla wax and nut shell wax as a gel factor.

6. Use of an oil-in-water gel Pickering emulsion according to any of claims 1 to 5 as an embedded delivery system for fat-soluble nutrients.

7. Use of an oil-in-water gel Pickering emulsion according to any of claims 1 to 5 as an animal fat substitute in sausages to reduce the animal fat content of the sausages and to increase the freeze-thaw stability of the sausages.

Technical Field

The invention relates to the technical field of gel, in particular to an oil-in-water gel Pickering emulsion and a preparation method and application thereof.

Background

Waxes are classified as lipids because they are non-polar and soluble in organic solvents, they self-assemble at room temperature to form crystalline materials, and thus, can be used as gelators to prepare oleogels for use in the pharmaceutical, cosmetic and food industries. Vegetable and animal waxes have replaced insoluble polymers due to their natural, solvent-free and low cost nature, which has attracted attention in the food industry because of its natural source of use in cleaning label products, and food industry scientists have made food grade oils (such as safflower oil, soybean oil, olive oil, etc.) into semi-solid oleogel systems by direct methods at room temperature by adding food grade natural waxes.

Emulsions are multi-scale, complex thermodynamically unstable systems composed of immiscible liquid phases, which are kinetically stable by the addition of emulsifiers. The traditional emulsifier is mostly a chemical polymer emulsifier, mainly comprises sucrose ester, monoglyceride and the like, and has the defects of relatively poor emulsifying property, large using amount, unsuitable HLB value, poor emulsifying effect of the single emulsifier, complex use, low consumer acceptance and the like. Emulsions stabilized with solid particles are generally called Pickering emulsions, which have wide applications in the fields of biomedicine, food processing, cosmetics, petroleum industry, agriculture, environmental protection and the like, based on the advantages of small emulsifier dosage, low cost, small harm to human bodies, high stability and the like. In recent years, the construction of a delivery system by taking an oil-in-water Pickering emulsion prepared by taking nano-cellulose as a stabilizer as a template has become a research hotspot in the fields of food, medicine and the like, but the application of the oil-in-water Pickering emulsion is limited by the defects of poor freeze-thaw stability and difficult emulsification of the oil-in-water Pickering emulsion.

Complex food systems are usually composed of a water phase and an oil phase, and oil gels are often required to be present in the food system in the form of an emulsion for improved product quality due to thermodynamic incompatibility of oil gels and water. In addition, compared to the oleogel, the Pickering emulsion of the oil-in-water gel can improve the bioavailability of hesperidin.

In order to improve the use of oleogels, emulsions in medicine and food bodies, the applicant has designed a new type of emulsion similar to solid lipid particles: oil-in-water gel Pickering emulsion using oil gel as disperse phase instead of partially or completely solidified fat and solid particle nano cellulose as stabilizer.

Disclosure of Invention

The invention aims to overcome the problems of thermodynamic incompatibility and difficult emulsification of a semisolid oil gel system and water and poor thermal stability of an oil-in-water Pickering emulsion, adopts nanocellulose (nanocellulose crystals, nanocellulose fibers, bacterial nanocellulose and the like) as a solid particle emulsifier, prepares the oil-in-water Pickering emulsion with good performance by a heating-homogenizing combined technology, and has good application in the aspects of embedding and delivering fat-soluble nutrient substances, reducing the animal fat content in sausages and improving the freeze-thaw stability of the sausages;

in order to achieve the purpose, the invention provides a preparation method of an oil-in-water gel Pickering emulsion, which comprises the following steps:

the first step is as follows: preparation of natural wax/vegetable oil mixed solution

1) Weighing natural wax by a balance, and then adding the natural wax into the vegetable oil according to the proportion of 1.5-20% w/v to obtain a natural wax-vegetable oil mixture;

2) heating the natural wax-vegetable oil mixture for 10-30 min on a magnetic stirrer platform with the rotating speed of 90-120 rpm and the temperature set to 130-160 ℃ to melt and uniformly disperse the natural wax in the vegetable oil to obtain a solution I;

the second step is that: preparation of nanocellulose suspensions

1) Preparing a nano-cellulose suspension solution with the concentration of 0.05-2.0%, adjusting the pH value of the nano-cellulose suspension solution to 4.0-8.0, adjusting the concentration of sodium chloride to 0.0-1.0 mol/L, and stirring the solution uniformly by using a magnetic stirrer;

2) heating the prepared nano-cellulose suspension in a water bath kettle at the temperature of 55-95 ℃ for 15-30 min to make the temperature of the nano-cellulose suspension reach 55-95 ℃ to obtain a solution II;

the third step: preparation of the emulsion

1) Mixing the solution I and the solution II according to a volume ratio of 1: 9-4: 6 to obtain a solution III, stirring the solution III for 1-3 min by using an emulsification homogenizer at a rotating speed of 8000-15000 rpm, and then placing the solution III in a water bath kettle with a water temperature of 55-95 ℃ for homogenization by using a high-intensity ultrasonic processor, wherein the ultrasonic homogenization conditions are as follows: the amplitude pressure is 55-80%, and the time is 1.5-3.0 min (opening for 3 s/closing for 3s), so as to obtain a solution IV;

2) and immediately putting the obtained solution IV into an ice water bath for cooling for 10-30 min to obtain the oil-in-water gel Pickering emulsion.

In particular, the vegetable oil is one of soybean oil, sunflower seed oil, rapeseed oil, peanut oil, olive oil and almond oil.

In particular, the nano-cellulose is one of nano-cellulose crystal, nano-cellulose fiber, bacterial nano-cellulose and modified nano-cellulose.

In particular, the modified nano-cellulose is one of acetylated nano-cellulose fiber, TEMPO oxidized bacterial cellulose and II type nanocrystalline cellulose ester.

Preferably, the natural wax is one of beeswax, spermaceti wax, Chinese insect wax, rice bran wax, carnauba wax, sugar cane wax, candelilla wax and nut shell wax as a gel factor.

An oil-in-water gel Pickering emulsion is used as an embedded delivery system of fat-soluble nutrient substances.

An oil-in-water gel Pickering emulsion is used as an animal fat substitute in sausages to reduce the animal fat content in the sausages and improve the freeze-thaw stability of the sausages.

The invention has the beneficial effects that:

the oil-in-water gel Pickering emulsion and the preparation process and application thereof are convenient and fast to operate, the technical problem of poor freeze-thaw stability of the oil-in-water Pickering emulsion is solved, the semisolid oil gel is used for replacing liquid vegetable oil as a disperse phase to prepare the oil-in-water gel Pickering emulsion, and the problem of poor freeze-thaw stability of the emulsion is obviously improved;

the oil-in-water gel Pickering emulsion is used for embedding and delivering fat-soluble nutrient substances, so that the freeze-thaw stability of the nutrient substances can be improved, and the bioavailability of the nutrient substances can be improved;

the oil-in-water gel Pickering emulsion is used for replacing animal fat in the sausage, and compared with the oil-in-water gel, the freeze-thaw stability of the sausage can be obviously improved.

Drawings

FIG. 1 is a flow chart of the preparation of an oil-in-water gel Pickering emulsion;

FIG. 2 is a schematic structural diagram of an oil-in-water gel Pickering emulsion prepared according to the present invention;

FIG. 3 is a graph of the appearance and appearance of the oil-in-water gel Pickering emulsion prepared in example 1, example 2 and example 3 after being placed at room temperature for 24 h;

FIG. 4 is the microstructure under a polarizing microscope of the oil-in-water gel Pickering emulsion prepared in example 1, example 2, example 3 after being left at room temperature for 24 h;

FIG. 5 is a macro-topography of a Pickering emulsion of oil-in-water gel and a common Pickering emulsion of oil-in-water. Wherein, the (a) is oil-in-water Pickering emulsion, the (b) is oil-in-water gel Pickering emulsion, and the times of freeze-thawing-0, 1, 2 and 3 mean that the times of freeze-thawing cycle are respectively 0, 1, 2 and 3;

FIG. 6 is a polarizing microscope image of a Pickering emulsion of an oil-in-water gel and a common Pickering emulsion of oil-in-water. Wherein, the (a) is oil-in-water Pickering emulsion, the (b) is oil-in-water gel Pickering emulsion, and the times of freeze-thawing-0, 1, 2 and 3 mean that the times of freeze-thawing cycle are respectively 0, 1, 2 and 3.

Detailed Description

Example 1

A preparation method of an oil-in-water gel Pickering emulsion comprises the following steps:

the first step is as follows: preparation of beeswax/peanut oil mixed solution

1) Weighing beeswax by a balance, and then adding the beeswax into peanut oil according to the proportion of 10.0% w/v to obtain a beeswax-peanut oil mixture;

2) heating the beeswax-peanut oil mixture on a magnetic stirrer platform with the rotation speed of 100rpm and the temperature set at 130 ℃ for 15min to melt the beeswax and uniformly disperse the beeswax in the peanut oil to obtain a solution I;

the second step is that: preparation of bacterial cellulose suspension

2) Preparing a bacterial cellulose suspension solution with the concentration of 0.5%, adjusting the pH value of the bacterial cellulose suspension solution to 7.0, adjusting the concentration of sodium chloride to 0.5mol/L, and stirring the solution uniformly by using a magnetic stirrer;

2) heating the prepared nano-cellulose suspension in a water bath at the temperature of 75 ℃ for 15min to enable the temperature of the nano-cellulose suspension to reach 75 ℃ to obtain a solution II;

the third step: preparation of the emulsion

2) Mixing the solution I and the solution II in a volume ratio of 2:8 to obtain a solution III, stirring the solution III with an emulsification homogenizer at a rotating speed of 12000rpm for 1min, then placing the solution III in a water bath kettle with a water temperature of 75 ℃ and homogenizing the solution III by a high-intensity ultrasonic processor, wherein the ultrasonic homogenization conditions are as follows: amplitude pressure of 65% and time of 2min (3 s on/3 s off) to obtain solution IV;

2) and immediately putting the obtained solution IV into an ice water bath for cooling for 10min to obtain the oil-in-water gel Pickering emulsion.

Example 2

A preparation method of an oil-in-water gel Pickering emulsion comprises the following steps:

the first step is as follows: preparation of rice bran wax/soybean oil mixed solution

1) Weighing rice bran wax by a balance, and then adding the rice bran wax into soybean oil according to the proportion of 5% w/v to obtain a rice bran wax-soybean oil mixture;

2) heating the rice bran wax-soybean oil mixture on a magnetic stirrer platform with the rotation speed of 90rpm and the temperature set at 160 ℃ for 10min to melt and uniformly disperse the rice bran wax in the soybean oil to obtain a solution I;

the second step is that: preparation of type II nanocellulose ester suspensions

3) Preparing a II type nanometer cellulose ester suspension solution with the concentration of 1.0 percent, adjusting the pH value of the II type nanometer cellulose ester suspension solution to 8.0, adjusting the concentration of sodium chloride to 0.3mol/L, and stirring the solution to be uniform by using a magnetic stirrer;

2) heating the prepared II type nano cellulose ester suspension in a water bath kettle at the temperature of 85 ℃ for 15min to ensure that the temperature of the nano cellulose suspension reaches 85 ℃ to obtain a solution II;

the third step: preparation of the emulsion

3) Mixing the solution I and the solution II according to a volume ratio of 3:7 to obtain a solution III, stirring the solution III for 2min by using an emulsification homogenizer at a rotating speed of 10000rpm, then placing the solution III in a water bath kettle with a water temperature of 85 ℃ and homogenizing the solution III by using a high-intensity ultrasonic processor, wherein the ultrasonic homogenization conditions are as follows: amplitude pressure 70% and time 1.5min (on 3 s/off 3s) to obtain solution IV;

2) and immediately putting the obtained solution IV into an ice water bath for cooling for 20min to obtain the oil-in-water gel Pickering emulsion.

Example 3

A preparation method of an oil-in-water gel Pickering emulsion comprises the following steps:

the first step is as follows: preparation of carnauba wax/sunflower seed oil mixed solution

1) Weighing carnauba wax by a balance, and then adding the carnauba wax into sunflower seed oil according to the proportion of 15% w/v to obtain a carnauba wax-sunflower seed oil mixture;

2) heating the mixture of carnauba wax and sunflower seed oil on a magnetic stirrer platform with the rotation speed of 110rpm and the temperature set at 150 ℃ for 20min to melt and uniformly disperse carnauba wax in sunflower seed oil to obtain a solution I;

the second step is that: preparation of acetylated nanocellulose fiber suspension

4) Preparing an acetylated nanocellulose fiber suspension solution with the concentration of 2.0%, adjusting the pH value of the acetylated nanocellulose fiber suspension solution to 6.0, adjusting the concentration of sodium chloride to 0.2mol/L, and stirring the solution to be uniform by using a magnetic stirrer;

2) heating the prepared acetylated nano cellulose fiber suspension in a water bath kettle at 86 ℃ for 20min to enable the temperature of the nano cellulose suspension to reach 86 ℃ to obtain a solution II;

the third step: preparation of the emulsion

4) Mixing the solution I and the solution II in a volume ratio of 4:6 to obtain a solution III, stirring the solution III for 2min by using an emulsification homogenizer at a rotating speed of 11000rpm, then placing the solution III in a water bath kettle with a water temperature of 86 ℃ and homogenizing the solution III by using a high-intensity ultrasonic processor, wherein the ultrasonic homogenization conditions are as follows: amplitude pressure of 65% and time of 2.0min (3 s/3 s) to obtain solution IV;

2) and immediately putting the obtained solution IV into an ice water bath for cooling for 20min to obtain the oil-in-water gel Pickering emulsion.

Example 4

This example evaluates oil-in-water gel Pickering emulsions as an embedded delivery system for fat-soluble nutrients.

The first step is as follows: preparation of a beeswax/olive oil mixed solution containing beta-carotene

1) Weighing beeswax on a balance, and then adding the beeswax into olive oil according to the proportion of 10% w/v to obtain a beeswax-olive oil mixture;

2) heating the mixture of beeswax and olive oil on a magnetic stirrer platform with rotation speed of 100rpm and temperature set at 140 deg.C for 15min (adding 1.0mg/mL beta-carotene during heating for 13 min) to disperse the system uniformly to obtain solution I;

the second step is that: preparation of nanocellulose suspensions

Preparing a II type nanocrystalline cellulose ester suspension solution with the concentration of 0.9%, adjusting the pH value of the nano cellulose suspension solution to 6.0, adjusting the concentration of sodium chloride to 0.1mol/L, and stirring the solution uniformly by using a magnetic stirrer;

2) heating the prepared II type nanocrystalline cellulose ester suspension in a water bath kettle at the temperature of 80 ℃ for 20min to ensure that the temperature of the II type nanocrystalline cellulose ester suspension reaches 80 ℃ to obtain a solution II;

the third step: preparation of beta-carotene-embedding emulsions

Mixing the solution I and the solution II according to a volume ratio of 4:6 to obtain a solution III, stirring the solution III for 2min by using an emulsification homogenizer at a rotating speed of 10000rpm, then placing the solution III in a water bath kettle with a water temperature of 80 ℃ and homogenizing the solution III by using a high-intensity ultrasonic processor, wherein the ultrasonic homogenization conditions are as follows: amplitude pressure of 55% and time of 2.0min (3 s/3 s) to obtain solution IV;

2) and immediately putting the obtained solution IV into an ice-water bath for cooling for 20min to obtain the beta-carotene embedded oil-in-water gel Pickering emulsion.

The embedding rate of beta-carotene in the oil-in-water gel Pickering system obtained by detection is 97.1%, the retention rate of beta-carotene stored at 37 ℃ for 15 days can reach 76.7%, and meanwhile, the retention rate of the oil-in-water Pickering emulsion system prepared under the same condition can be detected to be only 65.9% after the oil-in-water Pickering emulsion system is stored at 37 ℃ for 15 days.

In particular, the container holding the sample was completely covered with aluminum foil throughout the experiment to avoid exposure to light.

Example 5

Refer to example 1 preparation scheme. The freeze-thaw stability of the prepared oil-in-water gel Pickering emulsion (beeswax concentration in soybean oil of 9.0% w/v, oil gel/nanocellulose crystal suspension ratio of 4:6, pH 6.0, sodium chloride concentration of 0.1mol/L) was compared with the common oil-in-water Pickering emulsion (soybean oil/nanocellulose crystal suspension ratio of 4:6, pH 6.0, sodium chloride concentration of 0.1 mol/L).

The freeze-thaw treatment method comprises the following steps: putting 100mL of the emulsion into a 150mL beaker, and freezing the beaker in a constant-temperature refrigerator at-18 ℃ for 24 hours; after freezing, unfreezing for 24 hours at 4 ℃; such freeze-thaw cycle is repeated 0-3 times.

As shown in fig. 5 and 6, it was found that: compared with the common oil-in-water Pickering emulsion, the freeze-thaw stability of the oil-in-water gel Pickering emulsion is obviously improved.

Example 6

The pork sausage formula is shown in table 1:

the oil-in-water gel Pickering emulsion (the beeswax concentration in soybean oil is 9.0% w/v, the ratio of the oil gel to the nano-cellulose crystals is 4:6, the pH value is 6.0, and the sodium chloride concentration is 0.1mol/L) or the common oil-in-water Pickering emulsion (the soybean oil/the nano-cellulose crystals is 4:6, the pH value is 6.0, and the sodium chloride concentration is 0.1mol/L) is used for completely replacing 16% of pig backfat in pork sausages to prepare emulsified sausages (the formula is shown in the table 1), and the emulsion composition in the substitution scheme is shown in the table 2:

for meat emulsion before sausage cooking, compared with oil-in-water Pickering emulsion, the oil-in-water gel Pickering emulsion can obviously reduce the total juice loss of the meat emulsion and fat in the total juice loss by replacing fat, and improve the water holding capacity of the meat emulsion, as shown in Table 3:

for the sausage after the sausage is cooked, the texture parameters show that compared with the oil-in-water Pickering emulsion, the oil-in-water gel Pickering emulsion can obviously improve the hardness and chewiness of the sausage after the freeze-thaw treatment by replacing animal fat in the sausage, as shown in Table 4:

in conclusion, the oil-in-water gel Pickering emulsion can reduce the content of animal fat in the sausage by replacing the animal fat in the sausage, and simultaneously improves the freeze-thaw stability of the sausage compared with the oil-in-water Pickering emulsion.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.