Salt-reduced composite condensed fish oil microcapsule as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of salt-reduced composite condensed fish oil microcapsules, which comprises the following steps: embedding fish oil serving as a core material, soybean protein isolate serving as a first-layer wall material and sodium carboxymethyl cellulose serving as a second-layer wall material layer by layer. According to the salt-reduced composite condensed fish oil microcapsule and the application thereof, the core material is coated with two layers of different wall materials, so that the effects of stabilizing the core material and improving the encapsulation efficiency of the core material are achieved, and the problem of non-uniform embedding caused by single emulsification form of soybean protein isolate molecules is avoided; the functional property and the salty taste perception of the low-salt protein gel (0.2 M) can also be enhanced, and the salty taste value is increased by 28.38% and reaches the salinity level of 0.33 M. The fish oil microcapsule is prepared by compounding the soybean protein isolate and the sodium carboxymethyl cellulose, the salty taste of the low-salt protein gel is enhanced by optimizing the preparation process, and meanwhile, the mechanical strength of the low-salt protein gel is improved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to salt-reducing composite coacervated fish oil microcapsules and a preparation method and application thereof. Background Art

[0002] Regulating the spatial distribution of taste substances in the food matrix can trigger intermittent stimulation of taste receptor cells, reduce the adaptability of receptors to salty stimulation, reduce the amount of salt added without reducing the taste and other sensory properties, and enhance the perception of saltiness. In the food matrix, the interaction between components (such as proteins and polysaccharides) and sodium ions weakens the perception of saltiness. Therefore, it is challenging to reduce the salt content in semi-solid gel foods. Studies have shown that semi-solid gel foods with uneven salt distribution can be prepared by using alternating combinations of thin slices with different salt contents and thicknesses, but the implementation of this technology in the large-scale production of low-salt gel foods has limitations.

[0003] Colloidal dispersion systems with specific structures are widely used for the transfer and release of functional ingredients. The uneven distribution of gum arabic / soy protein isolate coacervates enhances the salty perception of pea starch-based gels. Therefore, electrostatic coacervation of proteins and polysaccharides can enhance salty perception while reducing sodium intake and achieve uneven distribution of sodium in the matrix. It is worth noting that differences in salty perception may also be related to the increase of the oil phase, thereby improving the mixing of sodium salt with saliva and accelerating the transmission of salt to the taste buds. For example, fish oil microcapsules with maltodextrin-chitosan as the wall material significantly enhance the salty perception of meat products. However, there is no direct relationship between the release rate of sodium and salty perception. Therefore, higher sodium release levels do not necessarily increase salty perception, and it remains challenging to directly enhance salty perception by adjusting the microcapsule wall material formulation and process. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] Another object of the present invention is to provide a method for preparing salt-reducing composite coacervated fish oil microcapsules, which uses fish oil as a core material, soy protein isolate as a first layer of wall material, and sodium carboxymethyl cellulose as a second layer of wall material, and is embedded layer by layer. The core material is coated with two layers of different wall materials, which not only has the effect of stabilizing the core material and improving the core material encapsulation rate, avoiding the problem of uneven embedding due to the single emulsification form of soy protein isolate molecules, but also can enhance the functional properties and saltiness perception of low-salt protein gel (0.2 M), and the saltiness value is increased by 28.38%, reaching a salinity level of 0.33 M.

[0006] Still another object of the present invention is to provide a salt-reduced complex coacervated fish oil microcapsule, which has a high encapsulation rate and can improve the mechanical strength of the gel.

[0007] Another object of the present invention is to provide the use of salt-reducing complex coacervate fish oil microcapsules as salt substitutes. The salt-reducing complex coacervate fish oil microcapsules of the present invention can reduce the amount of salt added in low-salt processed meat products, help enhance the functional properties and salty taste perception of low-salt protein gels, and are a good functional substance for replacing salt.

[0008] In order to achieve these purposes and other advantages according to the present invention, a method for preparing salt-reducing composite coacervation fish oil microcapsules is provided, which comprises: using fish oil as a core material, soy protein isolate as a first layer wall material, and sodium carboxymethyl cellulose as a second layer wall material, and embedding layer by layer.

[0009] Preferably, the method specifically comprises the following steps: Step 1, dissolving the soy protein isolate, adjusting the pH, adding sodium chloride to make the sodium ion concentration be 20-30 mM, heating in a water bath, and ultrasonically degassing to obtain a soy protein isolate stock solution; Step 2: Dissolve sodium carboxymethyl cellulose, heat in a water bath, add sodium chloride to make the sodium ion concentration be 20-30 mM, and stir to obtain a sodium carboxymethyl cellulose stock solution; Step 3, preparation of reduced-salt composite coacervate fish oil microcapsules: adding fish oil to the soy protein isolate stock solution obtained in step 1, homogenizing to obtain a primary emulsion, adding the sodium carboxymethyl cellulose stock solution obtained in step 2 to the primary emulsion to obtain a composite emulsion, adjusting the pH of the composite emulsion to 3-4, storing in a refrigerator at 0-4°C for 0.5-1.5 h to promote coacervation, centrifuging the coacervate, and freeze-drying to obtain reduced-salt composite coacervate fish oil microcapsules, wherein the volume ratio of fish oil to the total volume of the soy protein isolate stock solution and the sodium carboxymethyl cellulose stock solution is 1-2:1, and the volume ratio of the soy protein isolate stock solution to the sodium carboxymethyl cellulose stock solution is 8-10:1.

[0010] Preferably, step one specifically includes: S11, dissolving the soy protein isolate with deionized water, adjusting the pH to 9.0 with 0.1 M NaOH solution, and stirring for 20-40 min to fully hydrate the soy protein isolate; S12. Sodium chloride was added to make the sodium ion concentration 20-30 mM, and the mixture was heated in a water bath at 80°C for 5-15 min. The mixture was ultrasonically degassed at 120-140 W for 5-15 min to obtain a soy protein isolate stock solution with a mass volume percentage of 0.5-1.5%.

[0011] Preferably, step 2 specifically comprises: dissolving sodium carboxymethyl cellulose with deionized water, heating in a water bath at 35-45° C. for 50-70 min, adding sodium chloride to make the sodium ion concentration of the system 20-30 mM, and continuously stirring to promote full hydration of the polysaccharide to obtain a sodium carboxymethyl cellulose stock solution with a mass volume percentage of 0.5-1.5%.

[0012] Preferably, step three specifically comprises: adding fish oil to the soy protein isolate stock solution obtained in step one, homogenizing at a speed of 10000-14000 rpm for 1-3 min to obtain a primary emulsion, adding the sodium carboxymethyl cellulose stock solution obtained in step two to the primary emulsion to obtain a composite emulsion, immediately adjusting the pH of the composite emulsion to 3.5 with a 0.1 M HCl solution, storing in a refrigerator at 4°C for 1 h to promote coagulation, centrifuging the coagulated liquid at 800 g for 5 min, and freeze-drying at -40°C for 36 h to obtain reduced-salt composite coagulated fish oil microcapsules, wherein the volume ratio of fish oil to the total volume of the soy protein isolate stock solution and the sodium carboxymethyl cellulose stock solution is 1:1, and the volume ratio of the soy protein isolate stock solution to the sodium carboxymethyl cellulose stock solution is 10:1.

[0013] Preferably, in S12, the conditions for ultrasonic degassing treatment are: ultrasonic power is 130 W, and ultrasonic degassing time is 10 min.

[0014] Preferably, the fish oil is herring oil.

[0015] The object of the present invention can be further achieved by reducing salt and complex coacervating fish oil microcapsules.

[0016] Still another object of the present invention is to achieve the purpose by using the salt-reducing complex coacervated fish oil microcapsules as a salt substitute.

[0017] The present invention has at least the following beneficial effects: First, the preparation method of the salt-reducing composite coacervate fish oil microcapsules of the present invention uses fish oil as the core material, soy protein isolate as the first layer wall material, and sodium carboxymethyl cellulose as the second layer wall material, which are embedded layer by layer. The core material is coated with two layers of different wall materials, which not only has the effect of stabilizing the core material and improving the core material encapsulation rate, avoiding the problem of uneven embedding due to the single emulsification form of soy protein isolate molecules, but also can enhance the functional properties and salty taste perception of low-salt protein gel (0.2 M), and the saltiness value is increased by 28.38%, reaching a salinity level of 0.33 M.

[0018] Second, the salt-reduced composite coacervated fish oil microcapsules of the present invention have a high encapsulation rate and can improve the mechanical strength of the gel.

[0019] Third, the salt-reducing composite coacervate fish oil microcapsules of the present invention can reduce the amount of salt added in low-salt processed meat products, help enhance the functional properties and salty taste perception of low-salt protein gels, and are a good functional substance for replacing salt.

[0020] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The electronic tongue analysis results of the myofibrillar protein gel prepared in Example 4 and Comparative Examples 6 to 10 of the present invention are shown; Figure 2 This is a physical picture of the salt-reducing composite coacervate fish oil microcapsules prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0025] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0026] Example 1 A method for preparing salt-reducing composite coagulation fish oil microcapsules comprises the following steps: Step 1: Dissolve soy protein isolate (SPI) in deionized water, adjust the pH to 9.0 with 0.1 M NaOH solution, and stir continuously for 30 min to fully hydrate the SPI, add sodium chloride to make the sodium ion concentration 25 mM, heat in a water bath at 80°C for 10 min, and use an ultrasonic cleaner to perform ultrasonic degassing at 130 W for 10 min to prepare a 1% (w / v) SPI stock solution; Step 2: Dissolve sodium carboxymethyl cellulose (CMC) in deionized water, heat in a 40°C water bath for 60 min, add sodium chloride to make the sodium ion concentration of the system 25 mM, and stir continuously for 120 min to promote full hydration of the polysaccharide to obtain a 1% (w / v) CMC stock solution; Step 3: Add herring oil to the 1% (w / v) SPI stock solution obtained in step 1, homogenize at 12000 rpm for 2 min to obtain a primary emulsion, add the 1% (w / v) CMC stock solution obtained in step 2 to the primary emulsion to obtain a composite emulsion, immediately adjust the pH of the composite emulsion to 3.5 with 0.1 M HCl solution, store in a 4°C refrigerator for 1 h to promote coagulation, centrifuge the coagulant at 800 g for 5 min, and freeze-dry at -40°C for 36 h to obtain reduced-salt composite coagulant fish oil microcapsules (SPI-CMC-FO), wherein the core-wall (core is herring oil, wall is SPI stock solution and CMC stock solution) ratio is 1:1 (v / v), and the mixing ratio of SPI stock solution to CMC stock solution is 10:1 (v / v).

[0027] Example 2 A method for preparing salt-reducing composite coagulation fish oil microcapsules comprises the following steps: The difference between this embodiment and Example 1 is that in step 1, an ultrasonic cleaner is used to perform ultrasonic degassing at 120 W for 10 min to prepare a 1% (w / v) SPI stock solution; in step 3, the core-to-wall ratio is 1:0.5 (v / v).

[0028] Example 3 The difference between this embodiment and Example 1 is that in step 1, an ultrasonic cleaner is used to perform ultrasonic degassing at 140 W for 10 min to prepare a 1% (w / v) SPI stock solution; in step 3, the core-to-wall ratio is 1:1.5 (v / v).

[0029] Example 4 Preparation of low-salt myofibrillar protein gels for filling salt-reduced complex coacervated fish oil microcapsules: Phosphate buffer (100 mM NaCl, 20 mM sodium phosphate, 1 mM EGTA and 2 mM MgCl2, pH 7.0) was used to extract beef myofibrillar protein (MP). The specific extraction steps were as follows: beef sample was added to four times the volume of phosphate buffer and homogenized at 90,000 rpm for 3 min. The resulting homogenized solution was heated at 4,000 rpm for 3 min. g The protein precipitate was obtained after centrifugation at 4000 rpm for 15 min. The above process was repeated three times. Four volumes of Triton X-100 solution (1%) were added to the precipitate. The mixture was homogenized at 4000 rpm for 1 min and then at 4000 rpm for 30 min. g The protein was precipitated by centrifugation at 4000 °C for 15 min. Finally, 4 volumes of 100 mM NaCl solution were added to wash the precipitate and the precipitate was centrifuged at 4000 °C for 15 min. gAfter centrifugation for 10 min, the precipitate was collected and the above process was repeated twice. The myofibrillar protein precipitate was added to 20 mM sodium phosphate buffer (pH 7.2) and placed in a 4 ℃ refrigerator. The protein concentration was determined by the biuret method. The temperature of the entire extraction process was maintained at 4 ℃.

[0030] The salt-reduced composite coacervate fish oil microcapsules (SPI-CMC-FO) prepared in Example 1 were dispersed in a 3% low-salt MP (0.2 M, myofibrillar protein) solution at a ratio of 1:3 (v / v) to prepare a composite MP sol (MP-SPI-CMC-FO). The MP sol was heated from 25°C to 75°C at a rate of 1°C / min and kept at 75°C for 20 min to obtain a low-salt myofibrillar protein gel filling the composite microcapsules.

[0031] Comparative Example 1 The difference between this embodiment and Example 1 is that no ultrasonic degassing treatment is performed in step 1.

[0032] Comparative Example 2 Step 1: Dissolve SPI in deionized water, adjust the pH to 9.0 with 0.1 M NaOH solution, and stir continuously for 30 min to fully hydrate SPI, add sodium chloride to make the sodium ion concentration 25 mM, and heat in a water bath at 80°C for 10 min to prepare a 1% (w / v) SPI stock solution; Step 2: Dissolve apple pectin (AP) in deionized water, heat in a 40°C water bath for 60 min, add sodium chloride to make the sodium ion concentration of the system 25 mM, and stir continuously to promote full hydration of the polysaccharide to prepare a 1% (w / v) AP stock solution; Step 3: Add herring oil to the 1% (w / v) SPI stock solution obtained in step 1, homogenize at 12000 rpm for 2 min to obtain a primary emulsion, add the 1% (w / v) AP stock solution obtained in step 2 to the primary emulsion to obtain a composite emulsion, immediately adjust the pH of the composite emulsion to 4 using 0.1 M HCl solution, store in a 4°C refrigerator for 1 h to promote coagulation, centrifuge the coagulant at 800 g for 5 min, and freeze-dry at -40°C for 36 h to obtain reduced-salt composite coagulant fish oil microcapsules, wherein the core-to-wall ratio is 1:1 (v / v), and the mixing ratio of the SPI stock solution to the AP stock solution is 5:1 (v / v).

[0033] Comparative Example 3 The difference between it and Comparative Example 2 is that: Step 3: add herring oil to the 1% (w / v) SPI stock solution obtained in step 1, homogenize at 12000 rpm for 2 min to obtain a primary emulsion, add the 1% (w / v) AP stock solution obtained in step 2 to the primary emulsion to obtain a composite emulsion, immediately adjust the pH of the composite emulsion to 3.5 with 0.1 M HCl solution, store in a refrigerator at 4°C for 1 h to promote coagulation, centrifuge the coagulant at 800 g for 5 min, and freeze-dry at -40°C for 36 h to obtain reduced-salt composite coagulant fish oil microcapsules (SPI-AP-FO), wherein the ratio of core wall (herring oil to SPI stock solution and AP stock solution) is 1:1 (v / v), and the mixing ratio of SPI stock solution to AP stock solution is 8:1 (v / v).

[0034] Comparative Example 4 Step 1: Dissolve SPI in deionized water, adjust the pH to 9.0 with 0.1 M NaOH solution, and stir continuously for 30 min to fully hydrate SPI, add sodium chloride to make the sodium ion concentration 25 mM, and heat in a water bath at 80°C for 10 min to prepare a 1% (w / v) SPI stock solution; Step 2: Dissolve sodium alginate (SA) in deionized water, heat in a 40°C water bath for 60 min, add sodium chloride to make the sodium ion concentration of the system 25 mM, and stir continuously to promote full hydration of the polysaccharide to prepare a 1% (w / v) SA stock solution; Step 3: add herring oil to the 1% (w / v) SPI stock solution obtained in step 1, homogenize at 12000 rpm for 2 min to obtain a primary emulsion, add the 1% (w / v) SA stock solution obtained in step 2 to the primary emulsion to obtain a composite emulsion, immediately adjust the pH of the composite emulsion to 4 using 0.1 M HCl solution, store in a 4°C refrigerator for 1 h to promote coagulation, centrifuge the coagulant at 800 g for 5 min, and freeze-dry at -40°C for 36 h to obtain reduced-salt composite coagulant fish oil microcapsules (SPI-SA-FO), wherein the ratio of core wall (herring oil to SPI stock solution and SA stock solution) is 1:1 (v / v), and the mixing ratio of SPI stock solution to SA stock solution is 10:1 (v / v).

[0035] Comparative Example 5 The difference between it and Comparative Example 4 is that: Step 3: add herring oil to the 1% (w / v) SPI stock solution obtained in step 1, homogenize at 12000 rpm for 2 min to obtain a primary emulsion, add the 1% (w / v) SA stock solution obtained in step 2 to the primary emulsion to obtain a composite emulsion, immediately adjust the pH of the composite emulsion to 3.5 with 0.1 M HCl solution, store in a 4°C refrigerator for 1 h to promote coagulation, centrifuge the coagulant at 800 g for 5 min, and freeze-dry at -40°C for 36 h to obtain reduced-salt composite coagulant fish oil microcapsules (SPI-SA-FO), wherein the ratio of core wall (herring oil to SPI stock solution and AP stock solution) is 1:1 (v / v), and the mixing ratio of SPI stock solution to SA stock solution is 8:1 (v / v).

[0036] Comparative Example 6 The difference between it and Example 4 is that the composite coacervate fish oil microcapsules (SPI-CMC-FO) prepared in Comparative Example 1 are dispersed in a 3% low-salt MP (0.2 M, myofibrillar protein) solution at a ratio of 1:3 (v / v) to prepare a composite MP sol (MP-SPI-CMC-FO), the MP sol is heated from 25°C to 75°C at a rate of 1°C / min, and kept at 75°C for 20 min to obtain the myofibrillar protein gel filling the composite microcapsules.

[0037] Comparative Example 7 The difference between it and Example 4 is that the composite coacervate fish oil microcapsules (SPI-AP-FO) prepared in Comparative Example 3 are dispersed in a 3% low-salt MP (0.2 M, myofibrillar protein) solution at a ratio of 1:3 (v / v) to prepare a composite MP sol (MP-SPI-AP-FO), the MP sol is heated from 25°C to 75°C at a rate of 1.5°C / min, and kept at 75°C for 20 min to obtain the myofibrillar protein gel filling the composite microcapsules.

[0038] Comparative Example 8 The difference between it and Example 4 is that the composite coacervate fish oil microcapsules (SPI-SA-FO) prepared in Comparative Example 4 are dispersed in a 3% low-salt MP (0.2 M, myofibrillar protein) solution at a ratio of 1:3 (v / v) to prepare a composite MP sol (MP-SPI-SA-FO), the MP sol is heated from 25°C to 75°C at a rate of 1°C / min, and kept at 75°C for 20 min to obtain the myofibrillar protein gel filling the composite microcapsules.

[0039] Comparative Example 9 Preparation of low-salt myofibrillar protein gel: Low-salt MP (0.2 M, myofibrillar protein) sol was heated from 25°C to 75°C at a rate of 1°C / min and kept at 75°C for 20 min to obtain low-salt myofibrillar protein gel.

[0040] Comparative Example 10 Preparation of high-salt myofibrillar protein gel: High-salt MP (0.6 M, myofibrillar protein) sol was heated from 25 °C to 75 °C at a rate of 1 °C / min and kept at 75 °C for 20 min to obtain low-salt myofibrillar protein gel.

[0041] Performance Experiment 1. Encapsulation efficiency of microcapsules: In Examples 1 to 3 and Comparative Examples 1 to 5, the encapsulation efficiency of the salt-reducing composite coacervated fish oil microcapsules was determined. The encapsulation efficiency (EE, %) was calculated using the surface oil and total oil content. The calculation formula is: EE = (Wto-Wso) / Wto×100% Wherein, Wto represents the theoretical total oil content, and Wso represents the oil content on the surface of microcapsules.

[0042] The measurement results are shown in Table 1 below.

[0043] Table 1 Encapsulation efficiency of fish oil microcapsules (%) As shown in Table 1, the optimization of the ultrasonic-assisted degassing conditions of the SPI stock solution can significantly improve the encapsulation efficiency of the microcapsules for fish oil. Combined with the optimization of the core-to-wall ratio and the control of the sodium concentration of the system as defined in the present invention, the encapsulation efficiency of the microcapsules for fish oil is significantly enhanced. The encapsulation efficiency of the microcapsules prepared by combining apple pectin (AP) with sodium alginate (SA) polysaccharides and soy protein isolate for fish oil is weaker than that of sodium carboxymethyl cellulose (CMC).

[0044] 2. Electronic tongue analysis: The taste difference of protein gel was measured by SA402B electronic tongue for the myofibrillar protein gel of composite microcapsules obtained in Example 4 and Comparative Examples 6 to 10, the low-salt myofibrillar protein gel without fish oil microcapsules, and the high-salt myofibrillar protein gel without fish oil microcapsules. The specific steps are as follows: the myofibrillar protein gel sample was homogenized with ultrapure water (the mass ratio of gel sample to pure water was 1:100), the sample solution was filtered with a 0.45 μm microporous filter membrane, and the filtrate was transferred to a small beaker for testing. Each gel sample was tested four times, and the taste difference of the gel samples was distinguished by analyzing the response signal in the sensor.

[0045] The test results are as follows Figure 1As shown in Figure 1, the electronic tongue simulates the human taste perception system by integrating multiple sensors, each of which can detect different chemical or physical stimuli, thereby achieving taste recognition of specific substances. Figure 1 As shown, effective taste indicators include saltiness, umami, sourness, bitterness, astringency and richness. The saltiness of Example 4 is significantly higher than that of Comparative Examples 6 to 8, and the saltiness of Example 4 is significantly higher than that of the low-salt myofibrillar protein gel in Comparative Example 9 without the addition of fish oil microcapsules, indicating that the myofibrillar protein composite gel prepared by the salt-reducing composite coacervate fish oil microcapsules formed based on soy protein isolate and sodium carboxymethyl cellulose as wall materials can achieve the enhancement of saltiness in a low-salt environment. The saltiness of the myofibrillar protein gel filled with composite microcapsules prepared in Comparative Example 6 is not as good as that of Example 4. This is because ultrasonic degassing was not performed during the preparation of the composite microcapsules in Comparative Example 6, resulting in slightly poor solubility of soy protein isolate, and weak encapsulation efficiency and stability of the composite microcapsules.

[0046] In addition, from Figure 1 The specific values ​​of the electronic tongue test show that the saltiness of the low-salt myofibrillar protein gel without fish oil microcapsules in Comparative Example 9 and the high-salt myofibrillar protein gel without fish oil microcapsules in Comparative Example 10 are -14.94 and -1.43, respectively. Compared with the saltiness of the low-salt myofibrillar protein gel (0.2 M) without fish oil microcapsules, the saltiness of Example 4 (-10.67) increased by 28.58% {(-14.94-(-10.67)) / (-14.94)}, reaching a salinity level of 0.33 M, reflecting that the composite coacervate fish oil microcapsules prepared by the present invention have the ability to effectively enhance the saltiness.

[0047] 3. Protein gel texture characteristics: The protein gel strength of the myofibrillar protein gel filled with the composite microcapsules obtained in Example 4 and Comparative Examples 6 to 10, the low-salt myofibrillar protein gel without the addition of fish oil microcapsules, and the high-salt myofibrillar protein gel without the addition of fish oil microcapsules were measured. The specific steps are: using a TA.XT PLUS / 50 physical property tester equipped with a P / 0.5R cylindrical probe (diameter 12.7 mm) to analyze the texture characteristics of the myofibrillar protein gel (height 18 mm, diameter 20 mm) of the composite microcapsules, at room temperature, applying a trigger force of 5 g in a continuous cycle (5 seconds interval) to compress the myofibrillar protein gel to 50% of its initial height, wherein the pre-test speed, test speed and post-test speed are set to 1 mm / s, 1 mm / s and 10 mm / s, respectively.

[0048] The test results are shown in Table 2 below.

[0049] Table 2 Texture characteristics of myofibrillar protein gel Texture properties are important characteristics for evaluating the mechanical strength of protein gels. The mechanical strength of Example 4 of the present invention and Comparative Examples 6 to 10 was observed by measuring the texture properties. As shown in Table 2, the chewiness of Example 4 and Comparative Example 6 is 0.246 N and 0.217 N, respectively, indicating that the fish oil microcapsules formed by ultrasonic treatment during the preparation of the SPI stock solution require more energy from chewing to a swallowable state for the composite gel. The hardness and cohesiveness of Example 4 are significantly higher than those of Comparative Examples 6 to 8, and the hardness and chewiness of Example 4 are significantly higher than those of the low-salt myofibrillar protein gel in Comparative Example 9 to which no fish oil microcapsules are added. By comparison, the use of ultrasonic treatment and polysaccharide substrate optimization during the preparation of the SPI stock solution improves the strength and mechanical strength of the molecular bonding in the system of the protein gel, indicating that the encapsulation of fish oil can improve the mechanical strength of the gel while achieving flavor enhancement.

[0050] 4. Protein gel strength: The protein gel strength of the myofibrillar protein gel filled with the composite microcapsules obtained in Example 4 and Comparative Examples 6 to 10, the low-salt myofibrillar protein gel without the addition of fish oil microcapsules, and the high-salt myofibrillar protein gel without the addition of fish oil microcapsules were measured. The specific steps are: a TA.XT PLUS / 50 physical property tester (Stable Micro System Co., London, UK) equipped with a P / 0.5 probe (diameter 12.7 mm) was used to measure the gel strength of the myofibrillar protein gel of the composite microcapsules, wherein the test parameters were set as follows: a trigger force of 5 g, a pre-test and test speed of 1.0 mm / s, and a post-test speed of 3.0 mm / s.

[0051] The test results are shown in Table 3 below.

[0052] Table 3 Gel strength of myofibrillar protein gel The gel strength indicates the initial force required to destroy the gel, reflects the density of the gel structure, and corresponds to the texture characteristics of the composite gel. The gel strength of Example 4 of the present invention and Comparative Examples 6 to 10 was observed by measuring the gel strength. As shown in Table 3, the gel strength of Example 4 is significantly higher than that of Comparative Examples 6 to 9, and the gel strength of Example 4 is significantly higher than that of the low-salt myofibrillar protein gel in Comparative Example 9 without adding fish oil microcapsules, indicating that the gel strength can be improved by encapsulating fish oil. In summary, it is reliable to enhance the saltiness of low-salt protein gel by filling composite microcapsules.

[0053] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. A method for preparing salt-reducing composite coagulation fish oil microcapsules, characterized in that: include: Fish oil is used as the core material, soy protein isolate is used as the first layer wall material, and sodium carboxymethyl cellulose is used as the second layer wall material, and the encapsulation is performed layer by layer.

2. The preparation method according to claim 1, characterized in that The specific steps include: Step 1, dissolving the soy protein isolate, adjusting the pH, adding sodium chloride to make the sodium ion concentration be 20-30 mM, heating in a water bath, and ultrasonically degassing to obtain a soy protein isolate stock solution; Step 2: Dissolve sodium carboxymethyl cellulose, heat in a water bath, add sodium chloride to make the sodium ion concentration 20-30 mM, and stir to obtain a sodium carboxymethyl cellulose stock solution; Step 3, preparation of reduced-salt composite coacervate fish oil microcapsules: adding fish oil to the soy protein isolate stock solution obtained in step 1, homogenizing to obtain a primary emulsion, adding the sodium carboxymethyl cellulose stock solution obtained in step 2 to the primary emulsion to obtain a composite emulsion, adjusting the pH of the composite emulsion to 3-4, storing in a refrigerator at 0-4°C for 0.5-1.5 h to promote coacervation, centrifuging the coacervate, and freeze-drying to obtain reduced-salt composite coacervate fish oil microcapsules, wherein the volume ratio of fish oil to the total volume of the soy protein isolate stock solution and the sodium carboxymethyl cellulose stock solution is 1-2:1, and the volume ratio of the soy protein isolate stock solution to the sodium carboxymethyl cellulose stock solution is 8-10:

1.

3. The preparation method according to claim 2, characterized in that: Step 1 specifically includes: S11, dissolving the soy protein isolate with deionized water, adjusting the pH to 9.0 with 0.1 M NaOH solution, and stirring for 20-40 min to fully hydrate the soy protein isolate; S12. Sodium chloride was added to make the sodium ion concentration 20-30 mM, and the mixture was heated in a water bath at 80°C for 5-15 min, and then ultrasonically degassed at 120-140 W for 5-15 min to obtain a soy protein isolate stock solution with a mass volume percentage of 0.5-1.5%.

4. The preparation method according to claim 2, characterized in that: Step 2 specifically includes: dissolving sodium carboxymethyl cellulose with deionized water, heating in a water bath at 35-45°C for 50-70 min, adding sodium chloride to make the sodium ion concentration of the system 20-30 mM, stirring continuously for 120 min to promote full hydration of the polysaccharide, and preparing a sodium carboxymethyl cellulose stock solution with a mass volume percentage of 0.5-1.5%.

5. The preparation method according to claim 2, characterized in that: Step three specifically includes: adding fish oil to the soy protein isolate stock solution obtained in step one, homogenizing at a speed of 10000-14000 rpm for 1-3 min to obtain a primary emulsion, adding the sodium carboxymethyl cellulose stock solution obtained in step two to the primary emulsion to obtain a composite emulsion, immediately adjusting the pH of the composite emulsion to 3.5 with a 0.1 M HCl solution, storing it in a refrigerator at 4°C for 1 h to promote coagulation, centrifuging the coagulant at 800 g for 5 min, and freeze-drying it at -40°C for 36 h to obtain salt-reduced composite coagulant fish oil microcapsules, wherein the volume ratio of fish oil to the total volume of the soy protein isolate stock solution and the sodium carboxymethyl cellulose stock solution is 1:1, and the volume ratio of the soy protein isolate stock solution to the sodium carboxymethyl cellulose stock solution is 10:

1.

6. The preparation method according to claim 3, characterized in that: In S12, the conditions for ultrasonic degassing treatment are: ultrasonic power is 130 W, and ultrasonic degassing time is 10 min.

7. The preparation method according to claim 1, characterized in that: The fish oil is herring oil.

8. Salt-reduced complex coacervated fish oil microcapsules prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the salt-reducing complex coacervated fish oil microcapsules as claimed in claim 8 as a salt substitute.

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