Freeze-thaw resistant double-load emulsion filling gel micro powder as well as preparation method and application of freeze-thaw resistant double-load emulsion filling gel micro powder

Abstract

The invention discloses a freeze-thaw resistant double-load emulsion filling gel micro powder and a preparation method and application thereof, the freeze-thaw stability of emulsion filling gel is improved by increasing the content of low-viscosity polysaccharide araboxylan and adopting a greener and healthier mode; emulsion filling gel with good freeze-thaw stability is freeze-dried, ground and sieved to obtain micro powder with uniform particle size and good resolubility, and the micro powder has a better controlled release effect on fat-soluble nutrients.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and in particular relates to a freeze-thaw resistant double-loaded emulsion-filled gel micropowder and a preparation method and application thereof. Background Art

[0002] Functional foods with multiple bioactive ingredients and that can provide multiple health benefits have a broad market space. Emulsion-filled gel is an organic combination of O / W emulsion and hydrogel. The "double-loaded" emulsion-filled gel carrier that simultaneously loads fat-soluble and water-soluble nutrients can achieve the stabilization and precise delivery of the two nutrients, which is of great significance for the development and utilization of new functional food excipients with multiple functions. Studies have shown that beet pectin-soy protein isolate emulsion-filled gel can simultaneously encapsulate hydrophilic and lipophilic nutrients (CN113875979A). This method has the following limitations: ① The critical concentration of the gel is high, and the homogenizer is easily blocked during high-pressure homogenization; ② The particle size of the prepared primary emulsion is large, which may affect the bioaccessibility of the loaded fat-soluble nutrients; ③ The step-by-step gel method is cumbersome; ④ Large blocks of gel are prepared, which are not suitable for people with dysphagia or chewing difficulties, and cannot be more conveniently added to the food matrix as a functional excipient.

[0003] At present, most emulsion gel-based systems have high nutritional value and contain a large amount of water, which is easy to breed microorganisms and has a relatively short shelf life. Using certain drying methods to remove water from the gel base can effectively improve its storage stability. Compared with hydrogels, gel-based delivery systems with low water activity, such as dry gel blocks, gel-based powders or tablets, have smaller volume / weight and lower transportation / storage costs. In addition, the gel matrix environment with low water activity may provide longer-term stable protection and efficient delivery for the encapsulated active substances. Compared with other traditional drying methods (air drying, spray drying), gel-based delivery systems that carry heat-sensitive nutrients are more suitable for reducing moisture content using freeze-drying technology. Freeze-drying technology can keep the sample with good aroma and taste, and can maximize the retention of the biological activity of the loaded functional factors, but it has high requirements for the sample's anti-freeze-thaw ability. The freeze-thaw stability of emulsion-filled gels is crucial for their application in frozen or freeze-dried powder products, such as frozen desserts, frozen meat products, nutritional enhancers, etc. Under the inevitable temperature fluctuations and repeated freeze-thaw cycles in the supply chain, emulsion-filled gels are prone to de-oiling, water loss and flocculation. Researchers have found that increasing the salt ion concentration can improve the freeze-thaw stability of soy protein isolate emulsion-filled gels. However, too high a salt ion concentration is not conducive to human health and product production standards. It is urgent to seek a simpler, greener and harmless method to improve the freeze-thaw stability of emulsion-filled gels. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a freeze-thaw resistant double-loaded emulsion-filled gel micropowder.

[0007] In order to solve the above technical problems, the present invention provides the following technical solution: a method for preparing a freeze-thaw resistant double-loaded emulsion-filled gel micropowder, characterized in that: it comprises:

[0008] The oil and the protein solution are mixed evenly and homogenized at high speed to obtain a protein emulsion;

[0009] The protein is dispersed in deionized water and stirred evenly, and stored at low temperature overnight, and then immediately cooled after heat treatment, and then the pH is adjusted, and polysaccharide is added and stirred evenly to prepare a gel matrix;

[0010] The fat-soluble functional factors and the water-soluble functional factors are respectively embedded in the protein emulsion and the gel matrix, and then the gel inducer and laccase are added after the gel matrix and the protein emulsion are fully mixed, and the mixture is incubated in a water bath at room temperature to form an emulsion-filled gel, which is then frozen, dried, ground and sieved to obtain the freeze-thaw-resistant double-loaded emulsion-filled gel micropowder.

[0011] As a preferred embodiment of the preparation method of the present invention, the oil and the protein solution are mixed evenly, wherein the mass ratio of oil to water is 1:9 to 2:8, the oil is at least one of corn oil, soybean oil, peanut oil or other vegetable oils, and the protein solution is at least one of soybean protein isolate solution, whey protein isolate solution and pea protein isolate solution.

[0012] As a preferred embodiment of the preparation method of the present invention, the high-speed shear homogenization comprises shearing for 3 to 5 minutes at 10,000 to 13,000 rpm and homogenization at 500 to 700 bar.

[0013] As a preferred solution of the preparation method of the present invention, wherein: the protein is dispersed in deionized water and stirred evenly, wherein the volume ratio of the protein emulsion to the deionized water is 10%.

[0014] As a preferred embodiment of the preparation method of the present invention, the heat treatment is followed by cooling immediately and then adjusting the pH, wherein the heat treatment temperature is 90 to 95° C. and the heat treatment time is 15 to 30 min; and the pH is adjusted to 7.0.

[0015] As a preferred embodiment of the preparation method of the present invention, the adding of polysaccharide is stirred evenly, wherein the polysaccharide is at least one of corn arabinoxylan, pectin, wheat bran polysaccharide and beet polysaccharide.

[0016] As a preferred embodiment of the preparation method of the present invention, the gelling agent and laccase are added after the gelling agent and the protein emulsion are fully mixed, wherein the mass ratio of the gelling agent to the protein emulsion is 9:1, and the gelling agent is at least one of gluconolactone GDL, an organic acid, and dilute hydrochloric acid.

[0017] As a preferred embodiment of the preparation method of the present invention, the water bath incubation has a water bath temperature of 25-40°C.

[0018] Another object of the present invention is to overcome the deficiencies in the prior art and provide a freeze-thaw resistant double-loaded emulsion-filled gel micropowder, characterized in that the average particle size of the freeze-thaw resistant double-loaded emulsion-filled gel micropowder is 36 to 38 μm.

[0019] Another object of the present invention is to overcome the deficiencies in the prior art and provide a freeze-thaw resistant double-loaded emulsion-filled gel micropowder for use in nutritionally enhanced functional excipients.

[0020] As a preferred embodiment of the application of the present invention, the double-loaded emulsion-filled gel micropowder as a functional excipient can simultaneously achieve high-efficiency encapsulation, stabilization and gastrointestinal controlled release of thermosensitive water-soluble and fat-soluble nutrients.

[0021] Beneficial effects of the present invention:

[0022] (1) The present invention improves the freeze-thaw stability of the emulsion-filled gel by increasing the content of low-viscosity polysaccharide arabinoxylan, which is safer, healthier and more controllable than the salt ion regulation method.

[0023] (2) The present invention freeze-dries, grinds and sieves the emulsion-filled gel with good freeze-thaw stability to obtain a micropowder with uniform particle size (about 30 microns) and good resolubility. The microparticles have a good controlled release effect on fat-soluble nutrients. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0025] Figure 1 The freeze-thaw stability test result and SEM characterization diagram of the double-loaded emulsion-filled gel prepared in the examples of the present invention are shown.

[0026] Figure 2 This is a structural diagram of the freeze-thaw resistant double-loaded emulsion-filled gel micropowder prepared in an embodiment of the present invention under an optical microscope.

[0027] Figure 3 The volume fraction and average particle size of the freeze-thaw resistant double-loaded emulsion-filled gel micropowder prepared in the embodiment of the present invention.

[0028] Figure 4 This is a graph showing the controlled release results of water-soluble and fat-soluble nutrients by the double-loaded emulsion-filled gel micropowder prepared in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0032] The sources of raw materials used in the present invention are: soy protein isolate, purchased from Fuji Oil Co., Ltd.; COFCO Fortune corn oil, purchased from COFCO Group Co., Ltd.; laccase (38429, source Trametes versicolor) purchased from Sigma-Aldrich Company, USA; D-(+)-gluconolactone purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0033] Corn arabinoxylan, extracted in the laboratory, the extraction method is: grind corn bran into powder and pass through a 40-mesh sieve, mix the obtained corn bran powder with n-hexane (solid-liquid ratio = 1:7), and let it stand for 2 hours. Then remove the upper organic phase, place the precipitate in a 60℃ oven for hot air drying for 8 hours to obtain degreased corn bran powder. Mix the degreased corn bran powder with distilled water evenly (solid-liquid ratio = 1:10), boil for 30 minutes to gelatinize the starch in the bran, add high-temperature resistant α-amylase when the temperature drops to between 85 and 90℃, react for 30 minutes, and use iodine solution to check whether the starch in the solution has been completely hydrolyzed. Then add hydrochloric acid to adjust the pH of the mixed solution to 7, and add neutral protease (1500U / g bran) when the temperature rises to 50℃ to react for 3 hours. Filter and remove the supernatant, rinse the precipitate with boiling distilled water for 3-4 times, and then place the precipitate in a 65°C oven for hot air drying for 4 hours to obtain pretreated bran with oil and protein removed. Take 100g of pretreated dry bran powder (oil, protein and starch removed) and mix it thoroughly with 700mL NaOH solution (0.25M), and shake it in a constant temperature oscillator (25°C) at 150rpm in the dark for 4 hours. Centrifuge the reaction solution at 10000×g for 60 minutes and take the supernatant. Adjust the supernatant to pH=4 with 3M hydrochloric acid solution, centrifuge it again at 10000×g for 60 minutes, and take the supernatant. Slowly add 4 times the volume of anhydrous ethanol to the supernatant, and obtain a white flocculent precipitate after standing overnight, and freeze-dry to obtain corn arabinoxylan. The extraction method has mild conditions, and the ferulic acid content in the obtained corn arabinoxylan is 27.03±0.03μg / g, and the arabinose / xylose content is 0.82.

[0034] The instruments used in the embodiments of the present invention are: low-frequency nuclear magnetic resonance, Newmai PQ001 (Suzhou Newmai Analytical Instrument Co., Ltd.); Fourier transform infrared spectrometer SPECTRUM100, Perkin-Elmer, USA; scanning electron microscope S3400-2 Hitachi, Japan; optical microscope CX23 (Olympus, Tokyo, Japan).

[0035] Characterization and performance measurement methods in the embodiments of the present invention:

[0036] Low-frequency NMR: Low-field NMR measurements were performed using a Niumag desktop pulsed NMR analyzer PQ001. The instrument was equipped with a 0.5T permanent magnet, corresponding to a proton resonance frequency of 18 MHz at 32°C. Spin-spin relaxation time (T2) measurements were performed on gel samples using a Carr-Purcell-Meiboom-Gill (CPMG) sequence with an echo time of 0.2 ms, 6000 echoes, a period of 3000 ms, and 16 scans.

[0037] Fourier transform infrared spectroscopy determination method: Place spectrally pure potassium bromide in an oven at 105°C to dry. Weigh 200 mg of potassium bromide and mix with 3 mg of freeze-dried CFG, SPI, CFG gel, SPI gel and CFG-SPI double network gel samples, and grind them into fine powder in an agate mortar. Then put the mixed powder into a mold and use a tablet press to press the sample into a thin sheet (tablet pressing parameters: pressure 30MPa, 1min). Take out the thin sheet and place it in an infrared spectrometer for Fourier transform infrared spectroscopy detection. Potassium bromide is used as a blank control, and the spectral scanning range is 400cm -1 ~4000cm -1 OMINC 8.0 software was used to perform baseline correction and data analysis on the acquired data.

[0038] Scanning electron microscopy method: Field emission scanning electron microscopy (SEM) was used to observe the microstructure of the gel. All gel samples were cut into slices of about 1 mm, quickly frozen in liquid nitrogen, and then freeze-dried. The freeze-dried samples were fixed on the double-sided conductive carbon glue on the sample stage, and after gold spraying for 3 minutes, the acceleration voltage was set to 15 kV, and the focus, contrast, magnification and other parameters were appropriately adjusted to observe the samples.

[0039] Example 1

[0040] This embodiment provides a method for preparing a double-loaded emulsion-filled gel, comprising the following steps:

[0041] (1) The soy protein isolate solution (1.5%) was stirred for 5 h and stored at 4° C. overnight to achieve complete hydration of the soy protein isolate;

[0042] The corn oil and soybean protein isolate solution were fully mixed at an oil-water mass ratio of 1:9, sheared at 13000 rpm for 3 minutes in a high-speed shearing machine, and then homogenized at 700 bar in a high-pressure homogenizer at room temperature to prepare a stable soybean protein isolate emulsion.

[0043] (2) dispersing soy protein isolate powder in deionized water and stirring at room temperature for 3 h to prepare a 10% soy protein isolate solution, which was stored at 4° C. overnight until the soy protein isolate was fully hydrated;

[0044] The 10% soy protein isolate solution was then heat treated at 95°C for 30 min and then immediately cooled to 25°C in an ice bath.

[0045] (3) adjusting the pH value of a 10% soy protein isolate solution to 7.0, adding corn arabinoxylan powder, and stirring for about 6 hours to obtain a mixed solution of five components (soy protein isolate / corn arabinoxylan = 100 / 0, 99 / 1, 97 / 3, 95 / 5, 93 / 7) as a gel matrix;

[0046] The gel matrix was mixed evenly with the soy protein isolate emulsion obtained in step (1), and GDL (1%, w / w) and laccase (0.2 U / mg corn arabinoxylan) were added, and then transferred to a 25° C. water bath and incubated for 4 hours to form an emulsion-filled gel.

[0047] Example 2

[0048] This example is to test the freeze-thaw stability of the emulsion-filled gel prepared in Example 1, comprising the following steps:

[0049] The gel sample was frozen in a refrigerator at -18°C for 20 h and then thawed in a water bath at 25°C for 4 h to form a freeze-thaw cycle. In the actual measurement, the freeze-thaw cycle was repeated three times.

[0050] like Figure 1 As shown in A, all the soy protein isolate emulsion-filled gels had only one relaxation peak before freezing and thawing, indicating that the water molecules in the soy protein isolate emulsion-filled gels were mainly bound water. The peak relaxation time of the emulsion-filled gels increased with the decrease of the corn arabinoxylan content in the gel matrix, indicating that the reduction of the corn arabinoxylan content made the gel water holding capacity weaker.

[0051] After freeze-thaw treatment, the soy protein isolate emulsion-filled gel with low corn arabinoxylan content (97 / 3) turned into two relaxation peaks after freeze-thaw. One peak had a lower T2 relaxation time of 32.5ms, and the other peak had a higher transverse relaxation time of 329.3ms. This result shows that the bound water in the soy protein isolate emulsion-filled gel is partially converted into free water.

[0052] When the ratio of soy protein isolate / corn arabinoxylan is 95 / 5, the T value of soy protein isolate emulsion filled gel 21 34.5ms, T 22 After the same freeze-thaw treatment, the water molecules in the soy protein isolate emulsion filled gel with a high corn arabinoxylan ratio (soy protein isolate / corn arabinoxylan is 93 / 7) are still in a bound state (87.04ms).

[0053] The above results confirm that increasing the proportion of corn arabinoxylan can improve the water binding capacity of freeze-thaw emulsion filling gel.

[0054] observe Figure 1 B found that after freeze-thawing, the absorption bands of hydroxyl groups in the emulsion-filled gels with low corn arabinoxylan content (soy protein isolate / corn arabinoxylan mass ratio of 95 / 5 and 97 / 3) changed from 3297 cm -1 Move to 3299cm -1 , from 3291cm-1 Move to 3299cm -1 The shift of the absorption peak of hydroxyl to a higher wave number indicates that freeze-thaw treatment causes the hydroxyl in the gel to move to a free state. This may be because freeze-thaw treatment weakens the interaction between the gel matrix and water molecules.

[0055] In the FTIR spectrum of the soy protein isolate emulsion filled gel, the vibrations of the amide I band and the amide III band are located at 1659 cm -1 and 1242cm -1 After freeze-thawing, the characteristic peak of the amide III band of the emulsion-filled gel sample with the lowest corn arabinoxylan content (soy protein isolate / corn arabinoxylan mass ratio of 97 / 3) changed from 1242 cm -1 Shift to a lower wave number of 1240 cm -1 , the absorption peak of amide I band is from 1659cm -1 Red shifted to 1663 cm -1 , indicating that the β-folding in the secondary structure of soy protein isolate increased during the freeze-thaw process of the emulsion-filled gel, and the aggregation degree of protein molecules was further strengthened. When the soy protein isolate / corn arabinoxylan ratio was 93 / 7 and 95 / 5, the absorption peak position of the amide I band did not change significantly after freeze-thaw treatment, and the peak intensity was slightly weakened, indicating that the increase in the corn arabinoxylan content in the gel matrix may inhibit the freezing denaturation of soy protein isolate.

[0056] The SEM images of the soy protein isolate emulsion-filled gel before freeze-thaw show (e.g. Figure 1 C), the pore size becomes larger after freeze-thaw. This phenomenon occurs because low temperature causes the water in the gel to freeze, forming low-density ice crystals embedded in the gel network. The maturation of ice crystal austenite increases the average pore size inside the gel. In addition, the large expansion pressure generated during the freeze-thaw process destroys the gel network structure. The increase in temperature promotes the melting of ice crystals and the phase separation of gel and water. This is also the reason why the water retention of the gel deteriorates after freeze-thaw. The network pore size decreases with the increase of corn arabinoxylan content. After freeze-thaw treatment, the pore size becomes larger and the gel structure is destroyed.

[0057] The pore walls of the latex-filled gel with a high corn arabinoxylan content became thicker and rougher after freeze-thawing. The latex-filled gel with a low corn arabinoxylan content showed different degrees of phase separation between the corn arabinoxylan network and the soy protein isolate network after freeze-thawing. The possible reason is that the freezing treatment can further aggravate the formation of soy protein isolate aggregates in the matrix, causing the soy protein isolate network structure to reorganize, and finally forming a rough and unevenly distributed protein network. The aggregation and reorganization of soy protein isolate exposed the corn arabinoxylan network that was originally interpenetrating with it, and the interaction between corn arabinoxylan and soy protein isolate was correspondingly weakened, which eventually led to the phase separation of the corn arabinoxylan network and the soy protein isolate network in the corn arabinoxylan-soy protein isolate double network gel.

[0058] Example 3

[0059] This embodiment provides a preparation, characterization, and performance measurement of a freeze-thaw resistant double-loaded emulsion-filled gel micropowder, comprising the following steps:

[0060] (1) The soy protein isolate solution (1.5%) was stirred for 5 h and stored at 4° C. overnight to achieve complete hydration of the soy protein isolate;

[0061] The corn oil and soybean protein isolate solution were fully mixed at an oil-water mass ratio of 1:9, sheared at 13000 rpm for 3 minutes in a high-speed shearing machine, and then homogenized at 700 bar in a high-pressure homogenizer at room temperature to prepare a stable soybean protein isolate emulsion.

[0062] (2) dispersing soy protein isolate powder in deionized water and stirring at room temperature for 3 h to prepare a 10% soy protein isolate solution, which was stored at 4° C. overnight until the soy protein isolate was fully hydrated;

[0063] The 10% soy protein isolate solution was then heat treated at 95°C for 30 min and then immediately cooled to 25°C in an ice bath.

[0064] (3) adjusting the pH value of a 10% soy protein isolate solution to 7.0, adding corn arabinoxylan powder, and stirring for about 6 hours to obtain a mixed solution of five components (soy protein isolate / corn arabinoxylan = 100 / 0, 99 / 1, 97 / 3, 95 / 5, 93 / 7) as a gel matrix;

[0065] β-carotene and riboflavin were embedded in soy protein isolate emulsion and gel matrix, respectively. The embedding rate and loading amount of riboflavin and β-carotene in the emulsion-filled gel-based powder are shown in Table 1.

[0066] Then, the soy protein isolate emulsion and the gel matrix were evenly mixed, and GDL (1%, w / w) and laccase (0.2U / mg corn arabinoxylan) were added, and the mixture was transferred to a 25°C water bath and incubated for 4 hours to form an emulsion-filled gel. The mixture was freeze-dried at -60°C for 24 hours, ground with a mortar, and passed through a 200-mesh sieve to prepare a powder.

[0067] Table 1

[0068]

[0069] The double-loaded emulsion-filled gel-based powder has a high loading of riboflavin and β-carotene, ranging from 23.9 to 24.8 mg / g and 181.3 to 187.1 μg / g, respectively, with an embedding rate of more than 90.6%. With the increase of the proportion of corn fiber gum in the matrix, the embedding rate and loading of riboflavin and β-carotene in the powder both show an increasing trend. When the soy protein isolate / corn fiber gum increases to 93 / 7, the embedding rate of riboflavin in the powder reaches a maximum of 99.4%.

[0070] Dissolve 0.1g of the powder in 5g of deionized water and observe its microscopic morphology under a microscope. Figure 2 As shown in the figure, all emulsion-filled gel micropowder particles have a typical gel network structure, and oil droplets are embedded in the network. The gel particles are uniformly yellow as a whole, and no dispersed oil droplets are found outside the gel particles, proving that the emulsified oil droplets are stably fixed inside the gel network structure, and the powder preparation process has no significant effect on them, and no escape occurs. It further shows that after the powder is redissolved in water, the network structure is highly stable and can still effectively embed functional factors of different properties such as water-soluble vitamin B2 and fat-soluble β-carotene, making it a "dual-carrier" delivery system with good application performance.

[0071] 0.1g of powder was re-dissolved in 5g of deionized water, and the particle size distribution of oil droplets in the digestive juice was determined using a Malvern Mastersizer 3000. The refractive index of the oil phase was 1.47, the refractive index of the dispersed phase (water) was 1.33, and the relative refractive index was 1.105. The average particle size of the powder re-dissolved particles was determined using the volume weighted average method (D4,3). The results are shown in Figure 3 As shown in the figure, the particle size of the emulsion gel-based powder with a mass ratio of soy protein isolate / corn fiber gum of 93 / 7 after reconstitution is unimodal, and the average particle size is about 36-38μm. The particle size of the emulsion gel-based powder with a mass ratio of soy protein isolate / corn fiber gum of 95 / 5 and 93 / 7 after reconstitution is bimodal. Although the average particle size is larger than that of the emulsion gel-based powder with a mass ratio of 93 / 7, a small peak appears at about 10μm. In general, after all granular powders are reconstituted in water, the particle size distribution is in the range of 36-44μm.

[0072] Example 4

[0073] This embodiment provides a method for determining the controlled release effect of a double-loaded emulsion-filled gel micropowder on fat-soluble nutrients, comprising the following steps:

[0074] Oral stage: 7.5 mL of simulated saliva (SSF) containing 30 mg / mL mucin and 7.5 mL of the initial sample were thoroughly mixed at 37°C, and then the pH of the mixture was adjusted to 6.8 and continuously stirred at 100 rpm in a shaker for 10 min.

[0075] Gastric stage: 15 mL of the sample after simulated oral digestion was thoroughly mixed with 15 mL of simulated gastric fluid (SGF) (containing 2 mg / mL NaCl, 7 ml / L HCl, and 3.2 mg / mL pepsin). The pH value of the sample was adjusted to 2.0 and stirred continuously at 100 rpm for 2 h to simulate the gastric digestion process.

[0076] Small intestine stage: 30 ml of the sample from the gastric digestion stage was adjusted to pH 7.4 and thoroughly mixed with 1.5 ml of saline solution (containing 36.7 mg / mL CaCl2 and 18.7 mg / mL NaCl), 2.5 mL of pancreatic enzyme solution (24 mg / mL) and 3.5 mL of bile salt solution (54 mg / mL), and then digested in simulated intestinal fluid (SIF) at 100 rpm and 37°C for 2 h.

[0077] At the end of the reaction, the digestion solution was passed through a mesh sieve with a pore size of 1 mm. 15 mL of the sieved digestion solution was taken and 5 mL of extraction solution (n-hexane: ethanol = 3:2, v / v) was used to extract the β-carotene released in the digestion solution. After the digestion solution was centrifuged, the supernatant was taken to directly determine the riboflavin content release.

[0078] The results of the test are as follows Figure 4 As shown in the figure, riboflavin in the double-loaded emulsion-filled gel-based powder was rapidly released by 74% to 81% in the first 20 minutes in the stomach, and then slowly released. After 2 hours of simulated gastric digestion, the release amount was as high as 81% to 87%. The release amount of β-carotene in the powder decreased with the increase of the proportion of CFG in the gel matrix. This shows that the proportion of CFG has a good regulatory effect on the release of β-carotene in the gel carrier.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 3 is that the freeze drying in step (3) is replaced by microwave drying, and the remaining steps are the same as those in Example 3, to obtain a gel powder, in which the effective embedding rate of water-soluble and fat-soluble nutrients is low; and the emulsion-filled gel is prone to collapse during the drying process, and the micropowder obtained by subsequent grinding has poor rehydration stability.

[0081] Comparative Example 2

[0082] The freeze drying in step (3) was replaced by hot air drying, and the remaining steps were the same as those in Example 3 to obtain a gel powder, in which the effective embedding rate of water-soluble and fat-soluble nutrients was low; and the emulsion-filled gel was prone to collapse during the drying process, and the micropowder obtained by subsequent grinding had poor rehydration stability.

[0083] Comparative Example 3

[0084] The difference between this comparative example and Example 3 is that the laccase in step (3) is replaced by tyrosinase, and the remaining steps are the same as those in Example 3 to obtain a gel powder. However, the cross-linking degree of the emulsion-filled gel induced by the low-activity tyrosinase is not high, the porosity of the prepared gel micropowder is large, and the embedding rate of water-soluble nutrients is low.

[0085] Comparative Example 4

[0086] The difference between this comparative example and Example 3 is that the laccase in step (3) is replaced by glutaminase, and the remaining steps are the same as those in Example 3 to obtain a gel powder. However, the prepared gel has poor freeze-thaw stability, and severe phase separation occurs during the freezing process, resulting in severe damage to the gel structure. The final micropowder has a low encapsulation rate for water-soluble and fat-soluble nutrients, and has poor stability after rehydration.

[0087] Comparative Example 5

[0088] The difference between this comparative example and Example 3 is that the GDL in step (3) is replaced by dilute hydrochloric acid or citric acid, and the remaining steps are the same as those in Example 3 to obtain a gel powder. However, the resulting emulsion-filled gel network has a larger pore size, poor water retention, and a higher proportion of free water, resulting in poor freeze-thaw stability of the emulsion-filled gel. Severe phase separation and protein recombination are likely to occur during the freezing process, resulting in severe damage to the gel structure. The final micropowder has a low encapsulation rate for water-soluble and fat-soluble nutrients, and has poor stability after rehydration.

[0089] Comparative Example 6

[0090] The difference between this comparative example and Example 3 is that the laccase GDL and laccase in step (3) are replaced by tyrosinase and dilute hydrochloric acid, and the remaining steps are the same as Example 3 to obtain a gel powder. However, the emulsion-filled gel network has a large pore size, a rough pore wall, poor water retention, and a high free water ratio, resulting in poor freeze-thaw stability of the emulsion-filled gel, and protein reorganization and phase separation are prone to occur during the freezing process, resulting in serious damage to the gel structure. The micropowder prepared by freeze-drying and grinding has a low embedding rate for water-soluble and fat-soluble nutrients, a poor controlled release ability, and poor stability after rehydration, and is not suitable for use as a functional auxiliary material with stable performance in food matrices.

[0091] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the present invention.

Claims

1. A method for preparing a freeze-thaw resistant double-loaded emulsion-filled gel micropowder, characterized in that: include, The oil and the protein solution are mixed evenly and homogenized at high speed to obtain a protein emulsion; The protein is dispersed in deionized water and stirred evenly, and stored at low temperature overnight, and then immediately cooled after heat treatment, and then the pH is adjusted, and polysaccharide is added and stirred evenly to prepare a gel matrix; The fat-soluble functional factors and the water-soluble functional factors are respectively embedded in the protein emulsion and the gel matrix, and then the gel matrix and the protein emulsion are fully mixed, and then a gel inducer and laccase are added, and the mixture is incubated in a water bath to form an emulsion-filled gel, and then the mixture is frozen, dried, ground, and sieved to obtain the freeze-thaw-resistant double-loaded emulsion-filled gel micropowder.

2. The preparation method according to claim 1, characterized in that: The oil and the protein solution are mixed evenly, wherein the mass ratio of oil to water is 1:9-2:8, the oil is at least one of corn oil, soybean oil, peanut oil or other vegetable oils, and the protein solution is at least one of soybean protein isolate solution, whey protein isolate solution and pea protein isolate solution.

3. The preparation method according to claim 1, characterized in that: The high-speed shearing homogenization includes shearing for 3 to 5 minutes at 10,000 to 13,000 rpm and homogenization at 500 to 700 bar.

4. The preparation method according to claim 1, characterized in that: The protein is dispersed in deionized water and stirred evenly, wherein the volume ratio of the protein emulsion to the deionized water is 10%.

5. The preparation method according to claim 1, characterized in that: The method is immediately cooled after the heat treatment, and then the pH is adjusted, wherein the heat treatment temperature is 90-95° C. and the heat treatment time is 15-30 min; and the pH is adjusted to 7.

0.

6. The preparation method according to claim 1, characterized in that: The adding of polysaccharide and stirring are uniform, wherein the polysaccharide is at least one of corn arabinoxylan, pectin, wheat bran polysaccharide and beet polysaccharide.

7. The preparation method according to claim 1, characterized in that: The gel matrix and the protein emulsion are fully mixed and then a gel inducer and laccase are added, wherein the mass ratio of the gel matrix to the protein emulsion is 9:1, and the gel inducer is at least one of gluconolactone GDL, an organic acid, and dilute hydrochloric acid.

8. The preparation method according to claim 1, characterized in that: The water bath incubation, wherein the temperature of the water bath is 25-40°C.

9. The freeze-thaw resistant double-loaded emulsion-filled gel micropowder prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The average particle size of the freeze-thaw resistant double-loaded emulsion-filled gel micropowder is 36-38 μm.

10. Use of the freeze-thaw resistant double-loaded emulsion-filled gel micropowder as claimed in claim 9 in a nutritionally enhanced functional auxiliary material, characterized in that: The double-loaded emulsion-filled gel micropowder as a functional excipient can simultaneously achieve high-efficiency embedding, stabilization and gastrointestinal controlled release of heat-sensitive water-soluble and fat-soluble nutrients.

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