A modified coconut meal globulin and its preparation method and application

Abstract

The present invention provides a modified coconut meal globulin and a preparation method and application thereof, belonging to the technical field of coconut meal protein modification. Coconut meal globulin and polysaccharide are mixed in a mass ratio of 1: (0.25-4), stirred evenly to obtain a white suspension, hydrochloric acid is added for acidification, and the pH is adjusted to 3.5-4 to obtain the modified coconut meal globulin. Utilizing pH drive, the coconut meal globulin and gum arabic are compositely condensed, thereby improving the emulsification performance of the coconut meal globulin, making it exhibit properties similar to those of sodium caseinate, being able to more effectively emulsify the oil-water phase, and making the emulsion more uniform and stable. The modified coconut meal globulin provided by the present invention has a wide range of applications, and is not only suitable for the utilization of coconut meal, but also can be applied to the emulsification needs of other food industries and chemical industries, and has high application prospects and commercial value.

Description

Technical Field

[0001] The invention relates to the technical field of coconut meal protein modification, in particular to a modified coconut meal globulin and a preparation method and application thereof. Background Art

[0002] The coconut industry has potential but faces challenges in development and utilization. One of the main issues is the utilization of coconut meal as a by-product. Although coconut meal is rich in protein, it is currently mainly used as feed or directly discarded due to its poor palatability, which leads to environmental pollution and waste of protein resources. Globulin is the main component of protein in coconut meal and has high emulsification, but it is greatly affected by environmental factors and is prone to denaturation and aggregation, which limits its application. In order to overcome this problem, a variety of modification methods have been proposed, including physical, enzymatic and chemical modifications.

[0003] In the prior art, protein glycosylation is an effective means of emulsification modification. In this method, proteins form a viscoelastic adsorption layer on the surface of oil droplets to form a physical barrier to prevent the aggregation of droplets, thereby reducing the occurrence of coalescence and flocculation and keeping the emulsion stable. Polysaccharides reduce interfacial tension by changing the rheological properties of emulsions or forming a steric hindrance layer at the oil-water interface, thereby preventing emulsion flocculation and coalescence. The protein-polysaccharide complex is synergistically adsorbed on the interface of emulsion droplets, which can further improve the stability of the emulsion. These complexes are usually bound by covalent or non-covalent interactions, and non-covalent interactions include electrostatic interactions, hydrophobic interactions, hydrogen bonds, and van der Waals forces. These binding mechanisms allow protein-polysaccharide complexes to stabilize emulsions by changing interfacial behavior.

[0004] Patent CN116965478A discloses a method for preparing highly emulsifiable glycosylated soy protein isolate hydrolysate based on enzymolysis pretreatment-ultrasound combination. Soy protein isolate is moderately enzymolyzed by alkaline protease, and the enzymolyzed soy protein isolate and gum arabic are used as raw materials for Maillard reaction to prepare an enzymolyzed soy protein isolate gum arabic complex with excellent emulsifying properties in an ultrasonic-assisted environment. By combining enzymolysis pretreatment and ultrasonic treatment technology, the grafting degree of Maillard reaction between soy protein isolate and gum arabic is effectively improved, thereby significantly improving the emulsifying activity of soy protein isolate and the particle size distribution structure of the emulsion. However, its processing procedure is complicated, involving enzymolysis and ultrasonic treatment, and has high requirements for equipment and technology, which limits the promotion and application of the method. In addition, although the emulsifying properties are improved, in some cases, the emulsifying effect may be unstable or not as expected, and it is necessary to further optimize the processing conditions to obtain stable product performance.

[0005] Patent CN116369496A relates to a method for enhancing the emulsification properties of soy protein fibrils using gum arabic. The method first prepares soy protein fibrils and gum arabic solution, and then prepares the soy protein fibril-gum arabic complex. When 25% (v / v) gum arabic is added to the soy protein fibril emulsion, the emulsification properties and surface hydrophobicity of the emulsion are significantly improved, which is conducive to the practical application of the gum arabic soy protein fibril emulsion. However, its emulsification properties are still significantly different from those of sodium caseinate. Secondly, this method may be affected by factors such as the source of raw materials and processing technology, and further experiments and optimization are needed to ensure the stability and reliability of the product.

[0006] The academic paper "Effects of glycation method on the emulsifying performance and interfacial behavior of coconut globulins-fucoidan complexes" studied the improvement of the emulsifying performance of coconut globulins by glycosylation with fucoidan. With the increase of glycosylation degree, the globulins modified with fucoidan have better emulsifying stability and higher viscosity. In addition, the complex forms a thicker interfacial layer at the oil-water interface. In the academic paper "Effect of glycosylation with sugar beet pectin on the interfacial behavior and emulsifying ability of coconut protein", a glycosylated coconut globulin-fucoidan (CGF) complex was prepared by wet heat method to evaluate its emulsifying performance and interfacial behavior. The results of the study showed that the glycosylated coconut globulin-fucoidan complex with high grafting degree has better emulsifying stability. The glycosylation process disclosed in the above papers is accompanied by Maillard reaction, which often has problems such as low grafting degree, long reaction time, and easy aggregation and denaturation of proteins, and its application is limited.

[0007] At present, there are many soy protein emulsifiers on the market, but their emulsification performance is unsatisfactory and they have a beany smell. There is no high-emulsification plant protein product with high commercial value that can be comparable to macromolecular emulsifiers such as sodium caseinate. Therefore, for the coconut industry, developing new technologies and products that can more effectively utilize coconut meal will help improve its commercial competitiveness and reduce resource waste. Summary of the invention

[0008] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and provide a modified coconut meal globulin and a preparation method and application thereof, which utilizes a simple and effective pH-driven method to compound with gum arabic, successfully improving the performance of coconut meal globulin and opening up a new way for the application of plant protein in dairy products.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] The first object of the present invention is to provide a method for preparing modified coconut meal globulin. Coconut meal globulin and polysaccharide are mixed in a mass ratio of 1: (0.25-4), stirred evenly to obtain a white suspension, hydrochloric acid is added for acidification, and the pH is adjusted to 3.5-4 to obtain modified coconut meal globulin.

[0011] Furthermore, the polysaccharide is gum arabic.

[0012] Furthermore, the coconut meal globulin is extracted from coconut meal.

[0013] The second object of the present invention is to provide a modified coconut meal globulin prepared by the above-mentioned preparation method.

[0014] Further, the suspension turbidity OD of the modified coconut meal globulin is 600nm It is 0.35~0.6.

[0015] The third object of the present invention is to provide an application of the modified coconut meal globulin in the preparation of coconut products and plant-based products with coconut flavor.

[0016] Furthermore, the modified coconut meal globulin is added in the form of powder, granules or liquid dissolved in water.

[0017] Furthermore, the amount of modified coconut meal globulin added is 0.7% to 0.9% by mass concentration.

[0018] The fourth object of the present invention is to provide a food emulsifier comprising the modified coconut meal globulin.

[0019] The fifth object of the present invention is to provide a food stabilizer, characterized in that it contains the modified coconut meal globulin mentioned above.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a modified coconut meal globulin and a preparation method and application thereof. The modified coconut meal globulin utilizes a pH-driven method to compound the coconut meal globulin with gum arabic, thereby improving the emulsification performance of the coconut meal globulin, making it exhibit properties similar to those of sodium caseinate, being able to more effectively emulsify the oil-water phase, and making the emulsion more uniform and stable. The modified coconut meal globulin achieves a more efficient emulsification effect and a more stable emulsion, providing a new solution for the development of the coconut industry. The modified coconut meal globulin provided by the present invention has a wide range of applications, and is not only suitable for the utilization of coconut meal, but can also be applied to the emulsification needs of other food industries and chemical industries, and has high application prospects and commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The turbidity at different pH values ​​and coconut meal protein-arabic gum ratios;

[0023] Figure 2 The average particle size diagram and macroscopic image of the emulsions with different concentrations of modified coconut meal globulin after heat treatment;

[0024] Figure 3 The polydispersity index and macroscopic images of emulsions with different complex concentrations stored at low temperatures;

[0025] Figure 4 The emulsification index graph and macroscopic image of emulsions with different complex concentrations stored for 7 days;

[0026] Figure 5 The particle size distribution diagram of emulsions with different complex concentrations stored for 7 days. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0028] The coconut meal globulin involved in the present invention is extracted from coconut meal, and the specific process is: coconut meal is mixed with 0.5M NaCl in a ratio of 1:20 (g / mL), and stirred continuously at 50°C for 4 hours. Subsequently, centrifugation is performed at 4°C with a rotation speed of 10,000r / min for 30 minutes to remove insoluble residues. Then, the supernatant is collected by filtering with a 100-mesh nylon cloth to obtain a globulin fraction. The pH value of the obtained supernatant is adjusted to 4.3, and HCl is used to precipitate the globulin. The precipitate is neutrally washed and then freeze-dried. Finally, the obtained product is stored at -4°C until use.

[0029] When the modified coconut meal globulin of the present invention is used in the preparation of coconut milk products, the dairy products include coconut milk, cream and cheese. The modified coconut meal globulin can be added in the form of powder, granules or liquid soluble in water.

[0030] In the present invention, the food emulsifier means a substance that can improve the surface tension between various constituent phases in the emulsion to form a uniform dispersion or emulsion. It can be applied to foods such as cakes, margarine, ice cream, beverages, and dairy products. The food emulsifier containing modified coconut meal globulin provided by the present invention can be used in cakes to make fat evenly dispersed and prevent oil from seeping out; it can be used in ice cream to obtain an ice cream product with a dry, loose texture, good shape retention, and smooth surface; it can be used in yogurt to increase its gelling ability and hardness, making it taste better, thereby improving product quality; it can be used in milk solid beverages, it has good foaming properties, which can further improve product quality; it can be used in meat products. It can improve the water holding capacity of meat products.

[0031] The food stabilizer in the present invention refers to a type of food additive that can shape food and maintain a stable shape and texture. The food stabilizer containing modified coconut meal globulin provided by the present invention can be used in ice cream to obtain an ice cream product with good shape retention and stable storage period.

[0032] Example 1

[0033] This embodiment provides a method for preparing modified coconut meal globulin.

[0034] The specific steps are as follows:

[0035] First, coconut meal globulin (1.0%, w / v) was dissolved in deionized water and stirred continuously overnight at 600 rpm to ensure adequate hydration. Subsequently, the mixture was centrifuged at 6000 rpm for 15 minutes to remove undissolved substances or impurities. At the same time, gum arabic (1.0%, w / v) was dissolved in deionized water and stirred overnight at 500 rpm. Then, the solution was filtered using a filter membrane with a pore size of 0.45 μm to remove suspended solids or large particle impurities. Next, coconut meal globulin and gum arabic were mixed in a volume ratio of 1:1 and stirred continuously for 1 hour at 500 rpm to form a uniform white suspension, i.e., a globulin-gum arabic complex. Finally, high concentration hydrochloric acid was used to acidify the mixtures in different proportions, and the pH of the system was adjusted from 7.0 to 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, and 7.0, respectively, and the turbidity of the composite solution at different pH values ​​was measured.

[0036] Example 2

[0037] This embodiment provides a method for preparing modified coconut meal globulin.

[0038] The specific steps are basically the same as those in Example 1, except that the coconut meal globulin and gum arabic are mixed in a volume ratio of 1:2.

[0039] Example 3

[0040] This embodiment provides a method for preparing modified coconut meal globulin.

[0041] The specific steps are basically the same as those in Example 1, except that the coconut meal globulin and gum arabic are mixed in a volume ratio of 1:4.

[0042] Example 4

[0043] This embodiment provides a method for preparing modified coconut meal globulin.

[0044] The specific steps are basically the same as those in Example 1, except that the coconut meal globulin and gum arabic are mixed in a volume ratio of 1:0.5.

[0045] Example 5

[0046] This embodiment provides a method for preparing modified coconut meal globulin.

[0047] The specific steps are basically the same as those in Example 1, except that the coconut meal globulin and gum arabic are mixed in a volume ratio of 1:0.25.

[0048] Comparative Example 1

[0049] This comparative example provides a method for preparing coconut meal globulin.

[0050] The specific steps are basically the same as those in Example 1, except that the coconut meal globulin and gum arabic are mixed in a volume ratio of 1:0.

[0051] The results are as follows Figure 1As shown in the figure, coconut meal globulin-gum arabic produces four discrete phases due to the change of turbidity at different pH. In the pH 1.5-2.0 phase region, the turbidity of the solution increases with the increase of pH. This is because the reaction sites on the gum arabic sugar chain are protonated and the net negative charge decreases, indicating that a soluble complex of coconut meal globulin-gum arabic is formed. However, the density of the soluble complex is low and the interaction is weak; in the pH 2.0-4.0 phase region, the turbidity increases rapidly, indicating that an insoluble complex is formed. And when the coconut meal globulin / gum arabic ratio is 2:1, the maximum turbidity is observed at the pH value (pHopt, 3.5) when the amount of insoluble complex reaches the maximum. This trend is mainly due to the fact that as the pH value increases, the globulin and gum arabic have opposite charges, and complex coagulation occurs through electrostatic interaction, and charge balance is reached at pHopt. In the pH 4.0-5.5 phase region, the globulin is near the isoelectric point, resulting in an increase in the number of insoluble complexes; in the pH 5.5-7.0 phase region, the turbidity of the solution decreased significantly, because the globulin and gum arabic are negatively charged at this time, and the charges repel each other, resulting in a decrease in turbidity. In general, when the globulin / gum arabic ratio is 2:1, the maximum turbidity is observed at pHopt (3.5), at which the number of coconut meal globulin-gum arabic complexes formed is the largest.

[0052] In order to better explore the emulsifying properties of the modified coconut meal globulin of the present invention, the inventors conducted the following research:

[0053] The modified coconut meal globulin prepared in Example 4 was dispersed in deionized water at different concentrations (0.5%, 0.7% and 0.9%) to prepare suspensions. At the same time, a coconut meal globulin suspension with a concentration of 0.5% was prepared as a blank group (blank), and a sodium caseinate suspension with a concentration of 0.5% was prepared as a control group (SC). Subsequently, coconut oil (φ=40%) was added to each suspension and subjected to 400w ultrasonic treatment for 10 min to prepare an emulsion. Finally, the freshly prepared emulsion was stored at 4°C.

[0054] 1. Thermal stability

[0055] The emulsion was placed in a water bath and heated at two different temperatures and times (63°C / 30 min, 95°C / 10 min). After heating, the emulsion was cooled to room temperature and its average particle size and macrostructure were analyzed.

[0056] The results are as follows Figure 2As shown in the figure, the average particle size of all samples increased significantly after heat treatment, and only the blank treatment group showed oil-water separation. When the temperature was increased from room temperature to pasteurization temperature (63°C), the average particle size of the emulsion in the treatment group with a complex concentration of 0.7% increased by 42.1%. When the temperature was further increased to the heat processing temperature (95°C), the average particle size of the emulsion increased further. Compared with the SC treatment group, there was no significant difference in the average particle size change of the emulsion with a complex concentration of 0.7% treated at 63°C, while the average particle size of the blank group and the treatment groups with different concentrations changed greatly; after treatment at 95°C, the average diameter of the emulsions of different sample groups increased significantly, which may mean that the stability of the complex under high temperature treatment was affected, and it was more suitable for heating treatment at pasteurization temperature. These results show that the appropriate concentration of globulin-gum arabic complex can more effectively improve the thermal stability of the emulsion.

[0057] 2. Refrigerated and frozen storage stability

[0058] The fresh emulsion was transferred to a sample bottle and frozen in a refrigerator at -20°C and 4°C for 24 hours. The sample was then thawed and its polydispersity index was analyzed using a laser particle size analyzer and its macrostructure was observed.

[0059] The results are as follows Figure 3 As shown in the figure, it can be seen that all samples caused different degrees of demulsification under refrigeration and freezing treatment, and the polydispersity index increased significantly. In addition, compared with the emulsion in the blank treatment group, the addition of gum arabic significantly improved the refrigeration and freezing stability of globulin. It is worth noting that the polydispersity index is relatively small when the concentration of the globulin-gum arabic complex is 0.7%, and there is no significant difference in the polydispersity index of the emulsion in the sodium caseinate treatment group. When the concentration of the complex continues to increase, the excess complex will form flocculation, causing the polydispersity index of the emulsion to increase. These results show that at appropriate concentrations, the globulin-gum arabic complex can more effectively improve the refrigeration and freezing stability of the emulsion.

[0060] 3. Emulsion stability

[0061] Fresh emulsions with different treatments were filled into sample bottles. The stability of the emulsions was evaluated by the emulsification index after storage at room temperature for 7 days.

[0062] The emulsification index and appearance of different samples placed at room temperature for 7 days are as follows: Figure 4As shown. It can be seen that all emulsions have undergone stratification, indicating that the emulsion is a thermodynamically unstable system. In addition, the globulin without the addition of gum arabic showed a thicker whey layer, and the top emulsion layer (52%) and the bottom whey layer (48%) can be clearly observed. With the increase of the concentration of the complex, the fat floating rate of all emulsions showed a decreasing trend. When the concentration of the complex increased to 0.7% and 0.9%, enough complexes were distributed at the oil phase interface and tightly combined with the oil droplets, increasing the stability of the emulsion. The emulsion stability at this time was similar to that of the sodium caseinate treatment group. These results show that at appropriate concentrations, the globulin-gum arabic complex can more effectively improve the emulsification stability of the emulsion.

[0063] 4. Storage stability

[0064] The storage stability of the emulsion was evaluated by measuring the change in particle size distribution of the sample group and the control group after storage at room temperature (25° C.) for 7 days using a particle size analyzer for comparison.

[0065] The droplet size distribution results of fresh emulsion and emulsion stored for 7 days are as follows Figure 5 As shown. We can observe that the peak of the emulsion droplet size distribution shifted to the right after 7 days of storage, indicating that the droplets aggregated over time. In particular, the emulsion particle size of the blank group changed greatly, and the droplet size distribution was large, showing poor storage stability. Under the treatment of the complex concentration of 0.7%, the emulsion particle size changed less, showing a particle size distribution similar to that of the sodium caseinate treatment group. However, under the treatment of the complex concentration of 0.9%, the presence of excess complexes in the solution promoted the aggregation of droplets and did not show good storage stability.

[0066] In summary, the present invention uses sodium caseinate as a positive control and conducts comparative studies with modified coconut meal globulin. By comparing their emulsifying properties, the similarities and differences between modified coconut meal globulin and commercial emulsifiers can be revealed, further verifying the potential application value of modified coconut meal globulin in the food industry.

[0067] For matters not mentioned above, the prior art applies.

[0068] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing modified coconut meal globulin, characterized in that: Mix coconut meal globulin and gum arabic in a mass ratio of 1: (0.25-2), stir evenly to obtain a white suspension, add hydrochloric acid to acidify, adjust the pH to 3.5-4, and obtain modified coconut meal globulin; The turbidity OD of the suspension of the modified coconut meal globulin 600nm It is 0.35~0.

6.

2. The preparation method according to claim 1, characterized in that The coconut meal globulin is extracted from coconut meal.

3. A modified coconut meal globulin, characterized in that: The method is prepared by the preparation method described in any one of claims 1 to 2, wherein the mass ratio of the coconut meal globulin to gum arabic is 1:0.

5.

4. Use of the modified coconut meal globulin as claimed in claim 3 in the preparation of coconut products and plant-derived products with coconut flavor.

5. The use according to claim 4, characterized in that The modified coconut meal globulin is added in the form of powder, granules or liquid dissolved in water.

6. The use according to claim 5, characterized in that The amount of modified coconut meal globulin added is 0.7% to 0.9% by mass concentration.

7. A food emulsifier, characterized in that: The invention comprises the modified coconut meal globulin as claimed in claim 3.

8. A food stabilizer, characterized in that The invention comprises the modified coconut meal globulin as claimed in claim 3.

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