Preparation method and application of sodium alginate-tapioca protein / isolated whey protein double network gel

Abstract

The application discloses a preparation method and application of a sodium alginate-cyperus esculeus protein / isolated whey protein double-network gel, and comprises the following steps: step 1, mixing cyperus esculeus protein, isolated whey protein and sodium alginate to prepare a compound; and step 2, adding gluconic acid-delta-lactone and calcium carbonate into the compound to promote gel formation, so as to obtain a sodium alginate-cyperus esculeus protein / isolated whey protein compound gel induced by calcium acetate coordination. Compared with a pure protein gel, the sodium alginate-cyperus esculeus protein / isolated whey protein compound gel has excellent performances in texture characteristics, rheological characteristics and the like, and the water retention of the compound gel is also better than that of the pure protein gel. Moreover, the double network has a good encapsulation rate for curcumin and has a good slow-release effect.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method and application of a sodium alginate-taro protein / isolated whey protein double-network gel, and belongs to the field of food processing. BACKGROUND

[0002] Taro protein (TNP) is a protein extracted from taro. Research shows that taro protein contains 18 kinds of amino acids, among which essential amino acids for human body account for 46.03%, which is much higher than the value (36%) specified in the WHO / FAO model and is higher than that of soybean protein (41.3%). Therefore, taro protein is a plant protein with high nutritional value and has extremely high industrial utilization value. Research shows that taro protein has good emulsifying property and foaming property, but the gelatinization property needs to be improved.

[0003] Sodium alginate is a natural anionic polysaccharide composed of 1,4-linked alpha-L-guluronate (G-block) and beta-D-mannuronate (M-block) residues. Sodium alginate can rapidly interact with cations under mild conditions to form a high-toughness gel with an "egg-box" structure. Adding sodium alginate to different protein systems can produce gel systems with different characteristic structures, and these systems have significant advantages, such as good water retention and higher strength. Therefore, sodium alginate is widely used in high-protein foods to adjust the texture, structure and stability of gelatinous products.

[0004] The delivery system of a single taro protein-based gel is unstable to environmental stimuli in the processing process and in vitro simulated digestion experiments, which limits its application to some extent. By adjusting the interaction between proteins and polysaccharides, the gelation mechanism and the formation conditions, a multi-scale and multi-gradient composite gel structure can be prepared, which can overcome the defects of single protein gel and form a more stable gel network. SUMMARY

[0005] The application aims to overcome the problems of low mechanical strength, poor water retention and rapid release of bioactive ingredients of a single taro protein gel system, and to provide a high-efficiency and stable bioactive ingredient delivery system for functional foods and medical carriers by constructing a sodium alginate-taro protein / isolated whey protein double-network structure and optimizing the texture characteristics, water retention capacity and slow-release performance of the gel.

[0006] TECHNICAL SCHEME

[0007] A preparation method of a sodium alginate-taro protein / isolated whey protein double-network gel, comprising the following steps:

[0008] 1) preparing a composite protein solution of taro protein and isolated whey protein;

[0009] 2) heating the complex protein solution in a constant temperature water bath to obtain a pretreated complex protein solution;

[0010] 3) adding sodium alginate powder to the pretreated complex protein solution and mixing uniformly to obtain a polysaccharide-protein complex solution;

[0011] 4) sequentially adding calcium carbonate and glucono-delta-lactone to the polysaccharide-protein complex solution to form a double network gel.

[0012] Further, in step 1, the sago protein and the isolated whey protein are mixed at a mass ratio of 2:8, dissolved in deionized water, and stirred for 30 minutes to configure a solution with a total protein concentration of 10%.

[0013] Further, in step 2, the heating condition is 85℃ constant temperature water bath heating for 30 minutes.

[0014] Further, in step 3, the amount of sodium alginate added is 0-0.3% of the total mass of the solution.

[0015] Further, in step 4, 20mM calcium carbonate (CaCO3) and 1.2% (w / w) glucono-delta-lactone (GDL) are added to the polysaccharide-protein complex solution, and after stirring and mixing for 5 minutes, the gel is formed by standing at 25℃ for 24 hours.

[0016] Beneficial effects

[0017] In the present application, the sodium alginate-sago protein / isolated whey protein double network gel prepared by acid-calcium induction is characterized and analyzed in terms of microstructure, texture characteristics, rheological properties, water holding capacity and curcumin encapsulation rate of pure protein gel and composite gel with different mass ratios, the influence of adding sodium alginate on the double network is discussed, and the differences of composite gel with different mass ratios are analyzed, which provides a theoretical basis for the application of sago protein composite gel.

[0018] In the present application, the sodium alginate-sago protein / isolated whey protein double network gel prepared by acid-calcium induction has excellent performance in terms of hardness, chewiness, water holding capacity, rheological properties, etc. compared with pure protein gel, and the encapsulation rate of curcumin of the composite gel is also better than that of pure protein gel, and can achieve sustained release in simulated gastrointestinal digestion. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present application is attached Figure 7 Figure, wherein:

[0020] Figure 1Gel texture profile a (hardness); b (adhesiveness); c (springiness); d (cohesiveness); e (resilience); f (cumulative specific energy); g (specific energy) for the gel provided in Example 2 of the present invention;

[0021] Figure 2 Water holding capacity profile for the gel provided in Example 2 of the present invention;

[0022] Figure 3 Modulus profile a (storage modulus); b (loss modulus) for the gel in Example 2 of the present invention;

[0023] Figure 4 Apparent viscosity profile for the gel provided in Example 2 of the present invention;

[0024] Figure 5 Microstructure profile for the gel provided in Example 2 of the present invention;

[0025] Figure 6 Encapsulation efficiency of curcumin in the gel provided in Example 2 of the present invention;

[0026] Figure 7 Release rate of curcumin in the gel provided in Example 2 of the present invention under simulated gastrointestinal digestion; DETAILED DESCRIPTION

[0027] The present invention is further described in the following specific examples, but the embodiments of the present invention are not limited thereto.

[0028] Example 1: Method for preparing a double network gel

[0029] 1) Preparing a complex protein solution of cyamopropagta tau subsp. Junggarica protein and isolated whey protein;

[0030] 2) Heating the complex protein solution in a constant temperature water bath to obtain a pretreated complex protein solution;

[0031] 3) Adding sodium alginate powder to the pretreated complex protein solution and mixing uniformly to obtain a polysaccharide protein complex solution;

[0032] 4) Adding calcium carbonate and gluconic acid-delta-lactone to the polysaccharide protein complex solution in sequence to form a double network gel.

[0033] Example 2: Preparation of a double network gel

[0034] The preparation of the gel in this example includes the following steps:

[0035] Step 1 : 0.2 g of cyampepsis tetragonoloba protein and 0.8 g of isolated whey protein were weighed into 10 mL of deionized water, stirred at 25 °C for 30 min, and hydrated at 4 °C overnight to allow the proteins to fully hydrate. The solution was heated in a water bath at 85 °C for 30 min and then cooled to room temperature. 20 mM calcium carbonate (CaCO3) and 1.2% (w / w) glucono-delta-lactone (GDL) were added, and the mixture was stirred until homogeneous. The mixture was then allowed to stand at 25 °C for 24 h to form a gel, which was labeled 0.

[0036] Step 2: 0.2 g of cyampepsis tetragonoloba protein and 0.8 g of isolated whey protein were weighed into 10 mL of deionized water, stirred at 25 °C for 30 min, and hydrated at 4 °C overnight to allow the proteins to fully hydrate. The solution was heated in a water bath at 85 °C for 30 min and then cooled to room temperature. 0.005 g of sodium alginate was added to the solution and stirred magnetically at 25 °C for 2 h. 20 mM calcium carbonate (CaCO3) and 1.2% (w / w) glucono-delta-lactone (GDL) were added, and the mixture was stirred until homogeneous. The mixture was then allowed to stand at 25 °C for 24 h to form a gel, which was labeled 0.05.

[0037] Step 3: 0.2 g of cyampepsis tetragonoloba protein and 0.8 g of isolated whey protein were weighed into 10 mL of deionized water, stirred at 25 °C for 30 min, and hydrated at 4 °C overnight to allow the proteins to fully hydrate. The solution was heated in a water bath at 85 °C for 30 min and then cooled to room temperature. 0.01 g of sodium alginate was added to the solution and stirred magnetically at 25 °C for 2 h. 20 mM calcium carbonate (CaCO3) and 1.2% (w / w) glucono-delta-lactone (GDL) were added, and the mixture was stirred until homogeneous. The mixture was then allowed to stand at 25 °C for 24 h to form a gel, which was labeled 0.1.

[0038] Step 4: 0.2 g of cyampepsis tetragonoloba protein and 0.8 g of isolated whey protein were weighed into 10 mL of deionized water, stirred at 25 °C for 30 min, and hydrated at 4 °C overnight to allow the proteins to fully hydrate. The solution was heated in a water bath at 85 °C for 30 min and then cooled to room temperature. 0.015 g of sodium alginate was added to the solution and stirred magnetically at 25 °C for 2 h. 20 mM calcium carbonate (CaCO3) and 1.2% (w / w) glucono-delta-lactone (GDL) were added, and the mixture was stirred until homogeneous. The mixture was then allowed to stand at 25 °C for 24 h to form a gel, which was labeled 0.15.

[0039] Step 5: 0.2 g of cyampepsis tetragonoloba protein and 0.8 g of separated whey protein were weighed into 10 mL of deionized water, stirred at 25°C for 30 minutes, and hydrated at 4°C overnight to fully hydrate the proteins; heated in a water bath at 85°C for 30 minutes, and cooled to room temperature; 0.02 g of sodium alginate was added to the solution and stirred magnetically at 25°C for 2 h; 20 mM calcium carbonate (CaCO3) and 1.2% (w / w) glucono-delta-lactone (GDL) were added, and after stirring and mixing evenly, the mixture was left to stand at 25°C for 24 hours to obtain a gel sample, which was marked as 0.2.

[0040] Step 6: 0.2 g of cyampepsis tetragonoloba protein and 0.8 g of separated whey protein were weighed into 10 mL of deionized water, stirred at 25°C for 30 minutes, and hydrated at 4°C overnight to fully hydrate the proteins; heated in a water bath at 85°C for 30 minutes, and cooled to room temperature; 0.025 g of sodium alginate was added to the solution and stirred magnetically at 25°C for 2 h; 20 mM calcium carbonate (CaCO3) and 1.2% (w / w) glucono-delta-lactone (GDL) were added, and after stirring and mixing evenly, the mixture was left to stand at 25°C for 24 hours to obtain a gel sample, which was marked as 0.25.

[0041] Step 7: 0.2 g of cyampepsis tetragonoloba protein and 0.8 g of separated whey protein were weighed into 10 mL of deionized water, stirred at 25°C for 30 minutes, and hydrated at 4°C overnight to fully hydrate the proteins; heated in a water bath at 85°C for 30 minutes, and cooled to room temperature; 0.03 g of sodium alginate was added to the solution and stirred magnetically at 25°C for 2 h; 20 mM calcium carbonate (CaCO3) and 1.2% (w / w) glucono-delta-lactone (GDL) were added, and after stirring and mixing evenly, the mixture was left to stand at 25°C for 24 hours to obtain a gel sample, which was marked as 0.3.

[0042] The gel samples in the above steps were characterized and described in detail, and the specific results are as follows:

[0043] Texture properties and water holding capacity test

[0044] Texture test: A texture analyzer (Brookfield CT3, TPA mode) was used to determine the hardness and chewiness of the gel. The test parameters were: probe diameter 5 mm, test speed 0.5 mm / s, load 4.0 g, test distance 3 mm.

[0045] The results showed that the hardness of the 0.25% sodium alginate gel was 401.67 g, and the chewiness was 6.09 mJ Figure 1 a, 1d), which was significantly higher than that of the gel without the addition of sodium alginate (hardness 232.00 g, chewiness 2.86 mJ);

[0046] Water holding capacity test: The gel sample was placed in a centrifuge tube (15 mL) with filter paper at the bottom, and then centrifuged at 6000 rpm for 10 min. The water separated after centrifugation was carefully sucked out with a syringe and dried with filter paper. The ratio of the weight of the gel remaining in the centrifuge tube to the initial gel weight was calculated as the WHC. The calculation formula is as follows:

[0047] WHC = M1 / M2 x 100%

[0048] wherein M1 = the mass of the gel after centrifugation; M2 = the mass of the gel before centrifugation.

[0049] The WHC of the 0.25% sodium alginate gel was 82.46%( Figure 2 ), which was 16.9% higher than that of the gel without the addition of sodium alginate (70.50%).

[0050] Rheological property test

[0051] Frequency sweep: The test was performed at 25°C and 1% strain using a rheometer (DHR-1).

[0052] In the whole frequency range, the G' of all samples was greater than G", and both G' and G" increased with the increase of frequency, indicating that the gel structure was dominated by elasticity. The storage modulus (G') of the 0.25% sodium alginate gel reached 2850 Pa( Figure 3 a), which was significantly higher than the loss modulus (G" = 210 Pa), indicating that the gel was dominated by an elastic network;

[0053] Shear rate sweep: The apparent viscosity of the sample was recorded in the range of 0.1-100 S-1.

[0054] All gel samples had shear thinning properties, and the apparent viscosity decreased with the increase of shear rate. The addition of sodium alginate could enhance the shear thinning behavior of the composite gel, and the apparent viscosity increased significantly in a concentration-dependent manner with the increase of the concentration of sodium alginate. With the increase of the concentration of sodium alginate from 0.05% to 0.25%, the peak viscosity of the composite gel increased from 14134.9 Pa·s to 25301.4 Pa·s( Figure 4 ), and the peak apparent viscosity of the gel reached 25301.4 Pa·s, which was 78.9% higher than that of the gel without the addition of sodium alginate (14134.9 Pa·s);

[0055] Characterization of gel microstructure

[0056] The prepared gel sample was cut into small pieces (10 mm x 10 mm x 5 mm) and fixed with 2.5% (w / v) glutaraldehyde and freeze-dried. The dried sample after freeze-drying was sprayed with vacuum ion sputtering, and the microstructure of the gel sample was observed under a scanning electron microscope at 10 kV with a magnification of 100 times.

[0057] Gel without sodium alginate: Figure 5 ) : microstructure was layered, with large and irregular pores; network crosslinking density was low, and the structure was loose. Gel with 0.25% sodium alginate: Figure 5 ) : showed a uniform honeycomb-like porous structure, with significantly reduced pore size; the pores were uniformly distributed, and the network was dense and interconnected between fibers, forming a stable double network crosslinking system. The addition of sodium alginate significantly improved the microstructure of the gel, enhancing the mechanical strength and water holding capacity of the gel by filling the protein network pores and forming a polysaccharide-protein double network (Examples 2, 3).

[0058] Curcumin loading and release performance

[0059] Curcumin encapsulation rate determination: 1 g of gel was dispersed in 9 mL of anhydrous ethanol and ultrasonically extracted for 20 minutes. After centrifugation (6000 rpm for 10 minutes), the supernatant was taken and the absorbance at 425 nm was determined.

[0060] The encapsulation rate of the 0.25% sodium alginate gel was 92.17% ( Figure 6 ), which was 15.5% higher than that of the single protein gel (79.82%);

[0061] Gastrointestinal simulated digestion: The release rate was tested in simulated gastric juice (pH 2.5) and intestinal juice (pH 7.5). After 120 minutes of gastric digestion, the release rate of curcumin was 25.44%; after 60 minutes of intestinal digestion, the release rate was 47.53% ( Figure 7 ), which was significantly better than that of the single protein gel.

[0062] The above results show that, compared with protein gel, the hardness, chewiness, water holding capacity, and encapsulation rate of curcumin of the double network gel with added sodium alginate are significantly improved. The double network gel with added sodium alginate has a stronger gel structure, and increasing the concentration of sodium alginate can effectively enhance the properties of the double network gel. It was observed by scanning electron microscopy that, with the addition of sodium alginate, the pore size of the composite gel gradually decreased and the distribution became more uniform. The gastrointestinal simulation experiment showed that the sodium alginate-protein double network gel had a good protective effect on curcumin in the gastric simulation stage, and successfully achieved the slow release of curcumin in the intestinal simulation stage. Therefore, the sodium alginate-isolated whey protein / oysster protein double network gel can be used as an effective biomaterial for loading and slow releasing bioactive ingredients.

[0063] The above describes preferred embodiments of the present application, and the above-described examples are merely preferred specific embodiments of the present application, but the embodiments of the present application are not limited to the above-described examples. It should be noted that for ordinary skilled persons in the art, various changes and modifications can be made without departing from the spirit and scope of the present application, and these changes and modifications should be considered as falling within the protection scope of the present application.

Claims

1. A process for the preparation of a sodium alginate-tapioca protein / isolated whey protein double network gel, characterized in that, The method comprises the following steps: 1) preparing a complex protein solution of cyperus esculentus protein and isolated whey protein; In step 1), cyperus esculentus protein and isolated whey protein are mixed at a mass ratio of 2:8, dissolved in deionized water, and prepared into a solution with a total protein concentration of 10%; 2) heating the complex protein solution in a constant temperature water bath to obtain a pretreated complex protein solution; 3) adding sodium alginate powder to the pretreated complex protein solution and mixing uniformly to obtain a polysaccharide-protein complex solution; The amount of sodium alginate added in step 3) is 0.05-0.3% of the total mass of the solution; 4) sequentially adding calcium carbonate and glucono-delta-lactone to the polysaccharide-protein complex solution to form a double network gel.

2. The method for preparing a dual-network gel according to claim 1, characterized in that, The heating condition in step 2) is 85℃ constant temperature water bath heating for 30 minutes.

3. The method of preparing a dual-network gel according to claim 1, wherein In step 4), 20mM calcium carbonate and 1.2% w / w glucono-delta-lactone are added, and after stirring and mixing uniformly, the gel is formed by standing at 25℃ for 24 hours.

4. A sodium alginate-tapioca protein / isolated whey protein dual network gel, characterized in that, The double network gel is prepared according to the preparation method of any one of claims 1-3.

5. Use of a sodium alginate-tapioca protein / isolated whey protein double network gel according to claim 4, characterized in that For loading bioactive ingredients.

6. Use according to claim 5, characterized in that, The bioactive ingredient is curcumin.

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