Preparation of peanut protein-chitosan-tea polyphenol oil gel and application of peanut protein-chitosan-tea polyphenol oil gel in peanut butter

Abstract

The invention belongs to the technical field of food processing, and particularly discloses a preparation method of peanut protein-chitosan-tea polyphenol oleogel and application of the oleogel in peanut butter, peanut protein, chitosan and tea polyphenol are used as raw materials, an emulsion template method is adopted for preparing the oleogel, firstly, a peanut protein aqueous solution and a chitosan acetic acid solution are mixed, and then the oleogel is prepared. Adding tea polyphenol to form a composite solution, and freeze-drying to obtain composite particles; the compound particles are prepared into dispersion liquid, the dispersion liquid and peanut oil are homogenized according to a certain volume ratio of an oil phase to a water phase to form an emulsion template, the water phase is removed through pre-freezing and freeze-drying, and the oleogel is obtained. The oleogel prepared by the invention has better oil holding capacity and rheological property and shows good soft solid gel performance, and the oleogel is added into the peanut butter according to a certain proportion, so that the oil separation during the storage period can be reduced, and the increase of acid value and peroxide value can be slowed down, thereby improving the storage stability of the peanut butter.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a method for preparing peanut protein-chitosan-tea polyphenol oleogel and its application in peanut butter. It is a method for constructing peanut oil oleogel using peanut protein, chitosan and tea polyphenols as gelling agents through an emulsion template method, and the application of the oleogel in peanut butter. Background Technology

[0002] Peanut butter is a typical high-oil dispersed food, where solid particles coexist with the oil phase. During storage, the oil tends to rise to the surface and separate from the butter, accompanied by oxidative rancidity, leading to flavor degradation and a shortened shelf life. Current industrial methods often use hydrogenated vegetable oil or highly saturated plastic fats to improve consistency and stability. However, these solid fats often have a high content of saturated fatty acids, and some products may introduce trans fatty acids, making it difficult to meet the trends of health and clean labeling.

[0003] Oleogels are a type of structured lipid system that utilizes gelling agents to self-assemble into a three-dimensional network, fixing liquid vegetable oils into a near-solid state. Unlike chemical hydrogenation, oleogels typically do not alter the fatty acid composition of lipids and can be used as plastic fat substitutes in sauces, baked goods, and other foods. Currently commonly used oleogel agents include waxes, fatty acid derivatives, and proteins / polysaccharides. Among these, composite gelling agents constructed from natural biomolecules such as proteins, polysaccharides, and polyphenols possess both interfacial activity and antioxidant capacity, offering advantages such as being green and safe, widely available, and edible. However, achieving synergistic stabilization of "inhibiting oil separation + delaying oxidation" in complex systems such as peanut butter still requires further development.

[0004] Therefore, there is an urgent need to provide an oleogel and its application method that is constructed from natural raw materials, has a controllable preparation process, can simultaneously improve oil-soy sauce separation and delay oxidative rancidity in peanut butter systems. Summary of the Invention

[0005] This invention aims to provide a peanut protein-chitosan-tea polyphenol complex oleogel and its preparation method, and to apply it to peanut butter systems to improve storage stability. This oleogel can retain peanut oil by constructing a stable three-dimensional network structure without introducing animal-derived waxes / high-melting-point fats, thereby reducing oil separation and slowing oxidative deterioration in peanut butter during storage.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing peanut protein-chitosan-tea polyphenol oleogel involves using peanut protein, chitosan, and tea polyphenols as raw materials and employing an emulsion template method to prepare the oleogel. First, an aqueous solution of peanut protein is mixed with a chitosan acetic acid solution, and then tea polyphenols are added to form a composite solution. The composite particles are then freeze-dried to obtain composite particles. The composite particles are then formulated into a dispersion and homogenized with peanut oil at a certain volume ratio of oil phase to aqueous phase to form an emulsion template. The aqueous phase is removed by pre-freezing and freeze-drying to obtain the oleogel.

[0007] The specific steps of this preparation method are as follows: (1) Prepare peanut protein solution A and chitosan solution B respectively, wherein the mass concentration of peanut protein solution A is 2% and the mass concentration of chitosan solution B is 2%; (2) Mix chitosan solution B and peanut protein solution A at a chitosan:peanut protein mass ratio of 1:20 to 1:5, and dilute with 0.1 mol / L acetic acid solution to make the peanut protein mass concentration in the mixture 1%; (3) Add tea polyphenols to the mixture obtained in step (2) to make the mass concentration of tea polyphenols 0.25% to 1%, and stir magnetically at room temperature for 1 h to obtain peanut protein-chitosan-tea polyphenol composite solution. (4) Freeze-dry the composite solution obtained in step (3) for 72 h to obtain peanut protein-chitosan-tea polyphenol complex solid particles; (5) Dissolve the solid particles obtained in step (4) in acetic acid solution and add peanut oil, control the mass concentration of the complex to be 0.5% to 2% and the volume ratio of oil phase to water phase to be 2:8 to 4:6 (that is, the volume ratio of peanut oil to complex dispersion is 2:8 to 4:6), and then use a high-speed homogenizer to shear at room temperature to obtain the emulsion template. (6) The emulsion template obtained in step (5) was pre-frozen at -80 ℃ for 2 h and then freeze-dried for 72 h to remove the aqueous phase. Then it was sheared at 3000 r / min for 15 s to obtain the peanut protein-chitosan-tea polyphenol oil gel.

[0008] Furthermore, in step (1), the peanut protein solution A is prepared using distilled water as the solvent, and the chitosan solution B is prepared using 0.1 mol / L acetic acid solution as the solvent. Both are magnetically stirred at room temperature for 2 hours and then hydrated overnight at 4°C. The overnight hydration refers to allowing the solution to stand at 4°C to fully absorb water, swell, and reach a stable solution state.

[0009] Furthermore, in step (2), the volume ratio of chitosan solution B to peanut protein solution A is 1:5, 1:10, or 1:20. 。

[0010] Furthermore, after adding tea polyphenols in step (3), the pH of the composite solution is adjusted to 4-7, preferably 5, using hydrochloric acid and / or sodium hydroxide; the mass concentration of tea polyphenols is preferably 1%.

[0011] Furthermore, the volume ratio of the oil phase to the water phase in step (5) is 2:8, 3:7, or 4:6.

[0012] Furthermore, in step (5), the emulsion template is prepared by shearing at 10,000 to 20,000 r / min for 5 min at room temperature using a high-speed homogenizer, preferably 15,000 r / min.

[0013] The peanut protein-chitosan-tea polyphenol oil gel prepared by the method of the present invention can be used in peanut butter. Adding the oil gel to peanut butter and stirring evenly can reduce oil separation during storage and slow down the increase of acid value and peroxide value, thereby improving the storage stability of peanut butter.

[0014] The present invention also provides a peanut butter comprising a peanut butter base and a peanut protein-chitosan-tea polyphenol oil gel prepared by the above method, wherein the amount of oil gel added is 0.5% to 5% of the peanut butter mass.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) By combining chitosan with peanut protein and introducing tea polyphenols, the emulsifying properties and free radical scavenging ability of the system can be significantly improved (see Figure 1 This provides a foundation for the subsequent construction of a stable emulsion template and olegel network; the microstructure of the complex changes significantly with the formulation ratio and the amount of tea polyphenols added (see...). Figure 2 This is conducive to forming a denser network framework.

[0016] (2) The "emulsion template-freeze-drying" route can effectively retain peanut oil at a relatively low addition amount; the appearance and formation state of the oleogel under different complex concentrations and oil-water ratios are shown in the figure. Figure 3 Its oil separation (oil seepage) level is shown in Figure 4 .

[0017] (3) Oil gels exhibit distinct gel characteristics and structural strength (see...) Figure 5 ), and exhibits shear-thinning isorheological properties (see Figure 6 Confocal results show that the oil phase is embedded in the network structure and distributed more evenly (see...). Figure 7 ).

[0018] (4) Adding oil gel to peanut butter can reduce the rate of oil separation during storage and slow down the increase of oxidation indicators such as acid value and peroxide value (see [link]). Figure 8 This improves the storage stability of peanut butter. Attached Figure Description

[0019] Figure 1 The results show the effects of different chitosan-peanut protein blend ratios and tea polyphenol additions on (a) emulsifying activity index (EAI), (b) emulsifying stability index (ESI), (c) ABTS radical scavenging rate, and (d) OH radical scavenging rate of the system; (Note: different lowercase letters indicate significant differences between groups (p < 0.05), and the same letter indicates no significant difference) Figure 2 Microstructure characterization of peanut protein-chitosan-tea polyphenol complexes under different chitosan-peanut protein blending ratios and tea polyphenol addition amounts; Figure 3 The appearance morphology of oleogels prepared under different complex mass concentrations (0.5%–2%) and different oil phase:water phase volume ratios (2:8, 3:7, 4:6) is shown in the figure. Figure 4 The graph shows the oil exudation (oil seepage / oil leakage) rate of oleogels under different composite mass concentrations and different oil-to-water volume ratios; (Note: different lowercase letters indicate significant differences between groups (p < 0.05), and the same letter indicates no significant difference) Figure 5 The figure shows the dynamic rheological results of olegels (storage modulus G′ and loss modulus G″ as a function of strain) under different composite mass concentrations. Figure 6 The graph shows the change in apparent viscosity of olegels with shear rate under different composite mass concentrations. Figure 7 Confocal laser scanning microscopy images of oleogels under different complex concentrations (protein phase, oil phase, and overlay). Figure 8 The graph shows the changes in oil separation rate, acid value, and peroxide value of peanut butter during storage when the amount of oleogel added varies. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0021] Example 1: Preparation of peanut protein-chitosan-tea polyphenol composite solution and composite particles (1) Preparation of peanut protein solution A: Weigh peanut protein (peanut protein isolate), dissolve it in distilled water and adjust the mass concentration to 2%, stir magnetically at room temperature for 2 h and then hydrate at 4 ℃ overnight.

[0022] (2) Preparation of chitosan solution B: Weigh chitosan, dissolve it in 0.1 mol / L acetic acid solution and adjust the mass concentration to 2%, stir magnetically at room temperature for 2 h and then hydrate at 4 ℃ overnight.

[0023] (3) Mix chitosan solution B with peanut protein solution A according to the chitosan: peanut protein ratio of 1:20, 1:10 or 1:5, and make up the difference with 0.1 mol / L acetic acid solution to make the peanut protein concentration in the mixture 1%.

[0024] (4) Add tea polyphenols to the mixture in step (3) to make the mass concentration of tea polyphenols 0.25%, 0.5% or 1%, and adjust the pH of the system to 4 to 7 (preferably pH=5.0). Stir magnetically at room temperature for 1 h to obtain a composite solution.

[0025] (5) The obtained composite solution was placed in a freeze dryer and freeze-dried for 72 h to obtain peanut protein-chitosan-tea polyphenol composite solid particles.

[0026] The systems prepared using the above-mentioned different ratios and amounts of tea polyphenols exhibit the following emulsifying properties and antioxidant capacity: Figure 1 As shown, the microstructure changes of the complex are as follows: Figure 2 As shown. Example 2: Preparation of Emulsion Template (1) Dissolve the solid particles of the composite obtained in Example 1 in acetic acid solution to prepare composite solutions with a mass concentration of 0.5%, 1%, 1.5% or 2%, respectively.

[0027] (2) Add peanut oil to the complex solution according to the oil phase:water phase volume ratio of 2:8, 3:7 or 4:6.

[0028] (3) The emulsion template was prepared by shearing at room temperature using a high-speed homogenizer with a shearing speed of 10,000 to 20,000 r / min and a shearing time of 5 min (preferably 15,000 r / min and 5 min).

[0029] (4) The emulsion template was pre-frozen at -80 °C for 2 h and then freeze-dried for 72 h to remove the aqueous phase. The resulting solid was sheared at 3000 r / min for 15 s to obtain an oleogel. Example 3: Preparation and structural characterization of oleogel (1) The emulsion template obtained in Example 2 was pre-frozen at -80 °C for 2 h and then freeze-dried for 72 h to remove the aqueous phase. The resulting solid was sheared at 3000 r / min for 15 s to obtain an oleogel.

[0030] (2) The appearance of oleogels obtained under different complex concentrations and oil-to-aqueous phase volume ratios is as follows: Figure 3As shown; the results of oleogel oil separation rate are as follows. Figure 4 As shown.

[0031] (3) Dynamic strain scanning of the oleogel was performed using a rheometer. The results of the storage modulus G′ and loss modulus G″ are as follows: Figure 5 As shown; the results of apparent viscosity changing with shear rate are as follows: Figure 6 As shown.

[0032] (4) The distribution of protein and oil phases in the oleogel was observed using confocal microscopy, and the results are as follows: Figure 7 As shown. Example 4: Application of oleogloss in peanut butter (1) Take peanut butter base (homemade or commercially available peanut butter), add the oil gel prepared in Example 2, and add the oil gel at 0, 1%, 1.5% or 2% of the peanut butter mass, and stir evenly.

[0033] (2) Optionally, in order to simulate the thermal stress effect during processing and storage, the sample is subjected to temperature cycling treatment: after heating at 100 ℃ for 10 min, it is taken out, stirred evenly, and cooled to room temperature, and the process is repeated twice.

[0034] (3) The samples were subjected to accelerated storage at 30±1 ℃ for 60 days. Samples were taken every 15 days to determine the oil separation rate, acid value, and peroxide value. The results are as follows: Figure 8 As shown. (I) Performance evaluation of the ternary composite in Experimental Example 1 Figure 1 , Figure 2 ) Peanut protein-chitosan-tea polyphenol composite solutions were prepared by adding tea polyphenols to chitosan and peanut protein at ratios of 1:20, 1:10, and 1:5, respectively, to achieve mass concentrations of 0.25%, 0.5%, and 1%. The emulsifying activity index, emulsifying stability index, and free radical scavenging ability of the obtained samples were determined, and the results are as follows: Figure 1 As shown in the figure. The results indicate that, within the testing scope of this invention, when the ratio of chitosan to peanut protein is 1:5 and the mass concentration of tea polyphenols is 1%, the composite system exhibits superior performance in terms of emulsification properties, emulsification stability, and free radical scavenging ability.

[0035] Further observation of the microstructure of the complex yielded the following results: Figure 2 As shown in the figure, the results indicate that with the increase of both tea polyphenol and chitosan content, the complex structure tends to become denser and exhibits a three-dimensional network characteristic. Compared with the amount of tea polyphenol, the chitosan:peanut protein ratio has a more significant impact on the formation of the complex network structure. Under conditions of no chitosan or low chitosan content, the complex is more prone to aggregation and exhibits an irregular branched structure, a phenomenon consistent with the trend of changes in emulsifying properties. (II) Experimental Example 2: Optimization of oil-water phase ratio and complex concentration ( Figure 3 , Figure 4 ) The above ternary complex was dissolved in acetic acid solution to obtain complex solutions with mass concentrations of 0.5%, 1%, 1.5%, and 2%, respectively. Peanut oil was then added, and the oil-to-water volume ratio was controlled at 2:8, 3:7, and 4:6, respectively, to prepare emulsion templates and further obtain oleogels. The morphology of the oleogels under different preparation conditions is shown below. Figure 3 As shown in the figure. The results show that when the mass concentration of the composite is 1.5% and 2%, the oleogel exhibits good molding state at different oil phase:water phase volume ratios; when the mass concentration of the composite is 1%, a well-molded oleogel can also be formed at an oil phase:water phase volume ratio of 2:8 or 3:7.

[0036] The oil leakage rate test method for oleogloss is as follows: Weigh 1.5 g of oleogloss and place it in a 2 mL centrifuge tube. Centrifuge at 10000 r / min for 15 min at 10 ℃. After centrifugation, remove the surface-precipitated oil. The oil leakage rate is calculated using the following formula:

[0037] Where m0 is the mass of the empty centrifuge tube (g), m1 is the total mass of the centrifuge tube and sample after the sample is added (g), and m2 is the total mass of the centrifuge tube and remaining material after centrifugation to remove the separated oil (g).

[0038] Oil leakage rate results of oleogel under different conditions are as follows Figure 4 As shown. The results indicate that, within the testing scope of this invention, when the oil phase:water phase volume ratio is 2:8 and the composite mass concentration is 2%, the oil gel leakage rate is low.

[0039] (III) Experimental Example 3: Rheological and Microstructural Characterization of Olegels ( Figure 5 , Figure 6 , Figure 7 ) Rheological tests were performed on olegels prepared with different composite mass concentrations. Strain scanning results are shown below. Figure 5 As shown, the oleogel network structure is gradually destroyed as the strain increases, and the modulus shows a decreasing trend. Under the test conditions, the storage modulus G′ of each sample is higher than the loss modulus G″, exhibiting solid-like characteristics.

[0040] The shearing scan results are as follows Figure 6 As shown, the apparent viscosity of the olegel generally increases with increasing complex concentration; simultaneously, all samples exhibit shear thinning characteristics with increasing shear rate. The results indicate that increasing the complex concentration is beneficial for enhancing the strength of the olegel network structure, enabling it to possess rheological behavior similar to that of traditional plastic fats.

[0041] Under the condition that the oil phase:water phase volume ratio was fixed at 2:8, confocal microscopy was used to observe oleogels with different complex concentrations, and the results are as follows: Figure 7 As shown in the figure, the results indicate that the peanut oil phase is dispersed and embedded in the complex network structure; with increasing complex concentration, the network structure becomes more uniform and denser, thus being more conducive to the retention and fixation of the oil phase.

[0042] (iv) Experimental Example 4: Effect of Oil Gel Addition Amount on the Storage Stability of Peanut Butter Figure 8 ) The oil gel was added to the peanut butter at mass fractions of 0%, 1%, 1.5%, and 2%, and stirred thoroughly. To simulate the effects of thermal stress during processing and storage, the samples were subjected to temperature cycling: heated at 100 °C for 10 min, then removed, stirred thoroughly, and cooled to room temperature; this process was repeated twice. Subsequently, the samples were placed at 30 ± 1 °C for 60 days of accelerated storage, with samples taken every 15 days to determine the oil separation rate, acid value, and peroxide value. The results are as follows: Figure 8 As shown in the figure. The results indicate that, within the testing scope of this invention, an oil gel addition of 2% is more effective in reducing peanut oil precipitation and delaying the rise in oxidation indicators.

Claims

1. A method for preparing peanut protein-chitosan-tea polyphenol oleogloss, characterized in that, Oil gels were prepared using peanut protein, chitosan, and tea polyphenols as raw materials via an emulsion template method. First, an aqueous solution of peanut protein was mixed with a chitosan acetic acid solution, and then tea polyphenols were added to form a composite solution. The composite particles were then freeze-dried to obtain composite particles. The composite particles were then formulated into a dispersion and homogenized with peanut oil at a certain volume ratio of oil phase to aqueous phase to form an emulsion template. The aqueous phase was removed by pre-freezing and freeze-drying to obtain the oil gel.

2. The preparation method according to claim 1, characterized in that, Includes the following steps: (1) Prepare peanut protein solution A and chitosan solution B respectively, wherein the mass concentration of peanut protein solution A is 2% and the mass concentration of chitosan solution B is 2%; (2) Mix chitosan solution B and peanut protein solution A at a chitosan:peanut protein mass ratio of 1:20 to 1:5, and dilute with 0.1 mol / L acetic acid solution to make the peanut protein mass concentration in the mixture 1%; (3) Add tea polyphenols to the mixture obtained in step (2) to make the mass concentration of tea polyphenols 0.25% to 1%, and stir magnetically at room temperature for 1 h to obtain peanut protein-chitosan-tea polyphenol composite solution. (4) Freeze-dry the composite solution obtained in step (3) for 72 h to obtain peanut protein-chitosan-tea polyphenol complex solid particles; (5) Dissolve the solid particles obtained in step (4) in acetic acid solution and add peanut oil, control the mass concentration of the complex to be 0.5% to 2% and the volume ratio of peanut oil to complex dispersion to be 2:8 to 4:6, and then use a high-speed homogenizer to shear at room temperature to obtain the emulsion template. (6) The emulsion template obtained in step (5) was pre-frozen at -80 ℃ for 2 h and then freeze-dried for 72 h to remove the aqueous phase. Then it was sheared at 3000 r / min for 15 s to obtain the peanut protein-chitosan-tea polyphenol oil gel.

3. The preparation method according to claim 2, characterized in that, In step (1), the peanut protein solution A was prepared using distilled water as the solvent, and the chitosan solution B was prepared using 0.1 mol / L acetic acid solution as the solvent. After being magnetically stirred at room temperature for 2 h, the two solutions were allowed to stand at 4 ℃ overnight for hydration.

4. The preparation method according to claim 2, characterized in that, In step (2), the volume ratio of chitosan solution B to peanut protein solution A is 1:5, 1:10, or 1:

20. 。 5. The preparation method according to claim 2, characterized in that, After adding tea polyphenols in step (3), the pH of the composite solution is adjusted to 4-7 using hydrochloric acid and / or sodium hydroxide.

6. The preparation method according to claim 2, characterized in that, The volume ratio of chitosan solution B to peanut protein solution A is 1:5, the mass concentration of tea polyphenols in step (3) is 1%, and the pH of the composite solution is 5.

0.

7. The preparation method according to claim 2, characterized in that, The volume ratio of the oil phase to the water phase in step (5) is 2:8, 3:7 or 4:

6.

8. The preparation method according to claim 2, characterized in that, In step (5), the emulsion template is prepared by shearing at 10,000 to 20,000 r / min for 5 min at room temperature using a high-speed homogenizer, preferably 15,000 r / min.

9. The application of the peanut protein-chitosan-tea polyphenol oleogloss prepared according to the preparation method of claims 1-8 in peanut butter, characterized in that, Adding oil gel to peanut butter and stirring well can reduce oil separation during storage and slow down the increase in acid value and peroxide value, thereby improving the storage stability of peanut butter.

10. A peanut butter, characterized in that, The product comprises peanut butter base and peanut protein-chitosan-tea polyphenol oleogel prepared by the preparation method according to any one of claims 1 to 8, wherein the amount of oleogel added is 0.5% to 5% of the peanut butter mass.

Images