A method for preparing a high solubility chickpea protein dispersion

Abstract

The application discloses a preparation method of high-solubility chickpea protein dispersion, and belongs to the technical field of food protein deep processing. The method comprises the following steps: (1) dispersing chickpea protein powder in deionized water, adjusting the pH to neutral, fully stirring, and standing overnight; (2) performing water bath heating, high-pressure homogenization and alkaline amino acid combined treatment on the chickpea protein dispersion obtained in the step (1), uniformly stirring, and obtaining modified chickpea protein dispersion; and (3) standing the chickpea protein dispersion obtained in the step (2) overnight, so that the high-solubility chickpea protein dispersion is obtained. The method provided by the application can make the solubility of the chickpea protein dispersion reach more than 85%, has the advantages of greenness, safety, high efficiency, continuous large-scale processing and production and the like compared with the prior art, and further expands the application value of the chickpea protein in the development of plant protein beverages and functional foods.

Description

Technical Field

[0001] This invention belongs to the field of food protein deep processing technology, specifically relating to a method for preparing a highly soluble chickpea protein dispersion. Background Technology

[0002] With economic and social development and changes in dietary structure, people's demand for plant-based protein foods is increasing. Chickpea protein, as a representative of emerging plant proteins, has attracted much attention due to its high yield, balanced amino acid composition, and low allergenicity. Solubility, as a fundamental physicochemical property of proteins, is a key factor determining their functional properties. However, the rigid structure of natural chickpea protein results in poor water solubility, greatly limiting its application in food processing. Especially during the production of commercial chickpea protein, the protein structure undergoes drastic changes during extraction and spray drying, with the globulin portion easily denatured, further reducing the solubility. Therefore, effectively improving the solubility of chickpea protein is a problem that must be solved to broaden its deep processing and utilization.

[0003] Currently, the main methods for improving the solubility of chickpea protein include ultrasonic treatment and pH shifting treatment. However, the application of ultrasonic technology is very limited because the cavitation effect is confined to a small area, making it difficult to promote its application in industrial production. pH shifting treatment involves extreme acidic or alkaline environments, which can lead to pollution problems and does not meet the needs of green production. Therefore, it is necessary to find greener, safer, and more efficient modification methods to improve the functional properties of chickpea protein.

[0004] High-pressure homogenization is an effective method for improving the functional properties of proteins, offering advantages such as low cost, mild processing conditions, and no harmful substances produced. It has been used in the beverage and dairy industries for many years and can be applied to large-scale continuous protein production. Heat treatment, as a universal and convenient processing method, can also improve the functional properties of proteins to some extent. Studies have shown that certain high-pressure homogenization or heat treatment can improve the solubility of chickpea protein. However, the effects of a single modification method are limited and cannot meet the actual needs of food processing.

[0005] In recent years, the role of small-molecule basic amino acids—arginine (Arg), lysine (Lys), and histidine (His)—in enhancing the functional properties of food proteins has increasingly attracted researchers' interest. As components of protein raw materials, introducing basic amino acids into protein systems is therefore a green modification method. Furthermore, L-Arg, L-Lys, and L-His can not only be used as flavoring additives in food production, but also play a positive role in human tissue and immune regulation. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing a highly soluble chickpea protein dispersion. It fully utilizes the comprehensive modification advantages of heat treatment combined with high-pressure homogenization and alkaline amino acid treatment on the structure of chickpea protein to establish a method for preparing a highly soluble chickpea protein dispersion.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following solution:

[0008] A method for preparing a highly soluble chickpea protein dispersion includes the following steps:

[0009] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion of a certain concentration, adjust the pH to neutral, stir thoroughly, and let stand overnight to allow the chickpea protein to be fully hydrated.

[0010] (2) The chickpea protein dispersion obtained in (1) above was subjected to water bath heating treatment;

[0011] (3) The chickpea protein dispersion after water bath heating was subjected to high pressure homogenization.

[0012] (4) Add alkaline amino acids to the chickpea protein dispersion after high-pressure homogenization and stir evenly to obtain modified chickpea protein dispersion.

[0013] (5) Let the modified chickpea protein dispersion obtained in (4) stand overnight to obtain a highly soluble chickpea protein dispersion.

[0014] Furthermore, the chickpea protein dispersion in step (1) has a mass fraction of 5.0%.

[0015] Furthermore, in step (1), the pH is adjusted by HCl and / or NaOH.

[0016] Furthermore, in step (1), the stirring conditions are magnetic stirring at 600 rpm at 25°C for 2 to 2.5 hours.

[0017] Furthermore, the static temperature condition in step (1) is 4°C.

[0018] Furthermore, in step (2), the water bath heating conditions are: heating temperature 80-100℃, heating time 30-60min, preferably, the water bath heating conditions are 80℃, 30min.

[0019] Furthermore, in step (3), the high-pressure homogenization conditions are: homogenization pressure 60-100 MPa, homogenization times 2-4 times, preferably, homogenization pressure 80 MPa, homogenization times 2 times.

[0020] Furthermore, in step (3), before the high-pressure homogenization process, the chickpea protein dispersion treated by the water bath heating is cooled to room temperature using pre-cooling water; during the high-pressure homogenization process, the temperature of the system is controlled using a cooling water circulation system.

[0021] Furthermore, in step (4), the basic amino acid is L-Arg, L-Lys, or L-His. Preferably, the basic amino acid is L-Arg, and the mass fraction added is 0.5% to 1.0%.

[0022] Furthermore, in step (4), the stirring conditions are magnetic stirring at 600 rpm at 25°C for 2 to 2.5 hours.

[0023] Furthermore, in step (5), the settling conditions are the same as in step (1).

[0024] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention synergistically modifies chickpea protein by using heat treatment combined with high-pressure homogenization and alkaline amino acid treatment. Heat treatment promotes the exposure of active protein groups (hydrophobic groups, thiol groups, etc.), causing protein aggregates to extend. The high-speed shearing, impact, and collision mechanical forces generated by high-pressure homogenization, combined with short-term thermal effects, further decompose insoluble protein aggregates and promote the unfolding of protein secondary structures and the disruption of non-covalent bonds, thereby further improving protein solubility. The protein structural changes caused by heat treatment combined with high-pressure homogenization create favorable conditions for the subsequent interaction between alkaline amino acids and chickpea protein. Alkaline amino acids can increase the number of negative charges on the protein surface and enhance the electrostatic repulsion between protein molecules to inhibit protein aggregation, thereby significantly improving the solubility of chickpea protein dispersions.

[0025] The water bath heating treatment, high-pressure homogenization, and alkaline amino acid modification methods employed in this invention enable the chickpea protein dispersion to achieve a solubility of over 85%, providing excellent preconditions for its deep processing and utilization in food. Compared to existing technologies, this method offers advantages such as being green, safe, and efficient, and allows for large-scale and continuous processing. Furthermore, the introduction of alkaline amino acids can produce beneficial health effects on the human body; therefore, this invention also has significant reference value for the development of functional plant protein beverages. Attached Figure Description

[0026] Figure 1 The figure shows the solubility of chickpea protein dispersions in Example 1 and Comparative Examples 1-6; lowercase letters (ag) in the figure indicate significant differences between different treatment groups (P<0.05).

[0027] Figure 2The figure shows the solubility of chickpea protein dispersions in Example 2 and Comparative Examples 1-6; lowercase letters (ag) in the figure indicate significant differences between different treatment groups (P<0.05).

[0028] Figure 3 The figure shows the solubility of chickpea protein dispersions in Example 3 and Comparative Examples 1-6; lowercase letters (af) in the figure indicate significant differences between different treatment groups (P<0.05).

[0029] Figure 4 The images show the appearance of chickpea protein dispersions from Example 1 and Comparative Examples 1-6 (AF corresponds to Comparative Examples 1-6, G is Example 1, wherein the mass fraction of L-Arg added is 0.5%).

[0030] Figure 5 The images show the appearance of chickpea protein dispersions from Example 2 and Comparative Examples 1-6 (AF corresponds to Comparative Examples 1-6, G is Example 2, wherein the mass fraction of L-Arg added is 0.8%).

[0031] Figure 6 The images show the appearance of chickpea protein dispersions from Example 3 and Comparative Examples 1-6 (AF corresponds to Comparative Examples 1-6, G is Example 3, wherein the mass fraction of L-Arg added is 1.0%).

[0032] Figure 7 The microstructures of chickpea protein dispersions in Example 3 and Comparative Examples 1-6 are shown (AF corresponds to Comparative Examples 1-6, G is Example 3, wherein the mass fraction of L-Arg added is 1.0%).

[0033] Figure 8 The particle size of chickpea protein dispersions in Example 3 and Comparative Examples 1-6 is shown; lowercase letters (af) in the figure indicate significant differences between different treatment groups (P<0.05). Detailed Implementation

[0034] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0035] In the following examples, chickpea protein powder was purchased from Shaanxi Panier Biotechnology Co., Ltd., with a purity of over 80%; L-Arg was purchased from Shanghai Yuanye Biotechnology Co., Ltd., with a purity of over 98%. The instruments and equipment used were: SCIENTZ-207A high-pressure homogenizer (Ningbo Xinzhi Biotechnology Co., Ltd.); Nano ZS90 nanoparticle size potential analyzer (Malvin Ltd., UK); TU-1810 UV-Vis spectrophotometer (Beijing Purkinje General Instrument Co., Ltd.); and FV3000 laser confocal microscope (Olympus Corporation, Japan).

[0036] The testing and characterization methods involved in the embodiments and comparative examples of this invention are as follows:

[0037] Solubility determination: Chickpea protein was diluted to 10 mg / mL with deionized water. 5 mL of the chickpea protein dispersion was centrifuged at room temperature (4000 rpm / min, 10 min). The protein concentration of the supernatant was determined using the biuret method. A standard curve of protein concentration was prepared using bovine serum albumin. Solubility was calculated using the following formula:

[0038] Solubility (%) = Protein concentration in supernatant / Initial concentration of protein dispersion × 100

[0039] Particle size determination: Chickpea protein was diluted to 1 mg / mL with 0.01 M phosphate buffer (pH=7), and the particle size of chickpea protein was determined by dynamic light scattering. The results are expressed as average particle size values.

[0040] Microstructure determination: Chickpea protein was diluted to 5 mg / mL with deionized water, and 0.1% (w / v) rhodamine B was added for staining in the dark for 30 min. The sample was then observed under a confocal laser scanning microscopy (CLSM). The detection conditions were as follows: excitation wavelength 561 nm, emission wavelength range 570–620 nm, and objective lens magnification 10x.

[0041] Appearance observation: After the modified chickpea protein dispersion was left to stand overnight, its appearance was photographed with a smartphone.

[0042] Example 1

[0043] A method for preparing a highly soluble chickpea protein dispersion, comprising the following steps:

[0044] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0045] (2) The chickpea protein dispersion obtained in (1) above was heated in a water bath at 80°C for 30 min and homogenized twice under high pressure at 80 MPa. Then, 0.5% L-Arg basic amino acids were added and stirred until homogeneous.

[0046] (3) The dispersion obtained in (2) was left to stand overnight at 4°C to obtain a highly soluble chickpea protein dispersion.

[0047] Example 2

[0048] A method for preparing a highly soluble chickpea protein dispersion, comprising the following steps:

[0049] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0050] (2) The chickpea protein dispersion obtained in (1) above was heated in a water bath at 80°C for 30 min and homogenized twice under high pressure at 80 MPa. Then, 0.8% L-Arg basic amino acids were added and stirred until homogeneous.

[0051] (3) The dispersion obtained in (2) was left to stand overnight at 4°C to obtain a highly soluble chickpea protein dispersion.

[0052] Example 3

[0053] A method for preparing a highly soluble chickpea protein dispersion, comprising the following steps:

[0054] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0055] (2) The chickpea protein dispersion obtained in (1) above was heated in a water bath at 80°C for 30 min and homogenized twice under high pressure at 80 MPa. Then, 1.0% L-Arg basic amino acids were added and stirred until homogeneous.

[0056] (3) The dispersion obtained in (2) was left to stand overnight at 4°C to obtain a highly soluble chickpea protein dispersion.

[0057] Comparative Example 1: Heat-treated chickpea protein dispersion

[0058] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0059] (2) The chickpea protein dispersion obtained in (1) above was subjected to a water bath heating treatment at 80°C for 30 min;

[0060] (3) Let the dispersion obtained in (2) stand overnight at 4°C.

[0061] Comparative Example 2: High-pressure homogenized chickpea protein dispersion

[0062] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0063] (2) The chickpea protein dispersion obtained in (1) above was subjected to high-pressure homogenization at 80 MPa twice;

[0064] (3) Let the dispersion obtained in (2) stand overnight at 4°C.

[0065] Comparative Example 3: Chickpea Protein Dispersion Treated by Heat Treatment Combined with High-Pressure Homogenization

[0066] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0067] (2) The chickpea protein dispersion obtained in (1) above is first subjected to water bath heating at 80°C for 30 min, and then subjected to high pressure homogenization at 80 MPa twice.

[0068] (3) Let the dispersion obtained in (2) stand overnight at 4°C.

[0069] Comparative Example 4: Chickpea protein dispersion treated with alkaline amino acids

[0070] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0071] (2) The chickpea protein dispersion obtained in (1) above was subjected to alkaline amino acid treatment (adding L-Arg with a mass fraction of 0.5%, 0.8%, and 1.0%) and stirred evenly;

[0072] (3) Let the dispersion obtained in (2) stand overnight at 4°C.

[0073] Comparative Example 5: Chickpea protein dispersion treated with heat treatment combined with alkaline amino acids

[0074] (1) Disperse chickpea protein powder in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0075] (2) The chickpea protein dispersion obtained in (1) above was subjected to water bath heating treatment (80℃, 30min) and alkaline amino acid treatment (adding L-Arg with a mass fraction of 0.5%, 0.8%, and 1.0%), and stirred evenly;

[0076] (3) Let the dispersion obtained in (2) stand overnight at 4°C.

[0077] Comparative Example 6: Chickpea protein dispersion treated with high-pressure homogenization combined with alkaline amino acids

[0078] (1) Disperse chickpea protein in deionized water to form a chickpea protein dispersion with a mass fraction of 5.0%. Adjust the pH to neutral, stir thoroughly, and then let stand overnight at 4°C to allow the chickpea protein to fully hydrate.

[0079] (2) The chickpea protein dispersion obtained in (1) above was subjected to high pressure homogenization (80 MPa, twice) and alkaline amino acid treatment (adding L-Arg with a mass fraction of 0.5%, 0.8%, and 1.0%), and stirred evenly;

[0080] (3) Let the dispersion obtained in (2) stand overnight at 4°C.

[0081] like Figure 1-3 As shown, the solubility of chickpea protein dispersions in Comparative Examples 1-5 was all below 50%, indicating that single treatment with heat, high-pressure homogenization, and L-Arg, or heat combined with L-Arg treatment, cannot prepare highly soluble chickpea protein dispersions. Although the solubility of Comparative Example 6 was improved compared to Comparative Examples 1-5, its value was still below 85%, thus not meeting the needs of practical applications. Among all treatment groups, Examples 1-3 had the highest solubility, all above 85%, indicating that the combined treatment of heat, high-pressure homogenization, and L-Arg can synergistically improve the solubility of chickpea protein dispersions, thereby preparing highly soluble chickpea protein dispersions.

[0082] from Figure 4-6It can be seen that the chickpea protein dispersions in Comparative Examples 1-5 exhibited significant phase separation, with sedimentation at the bottom and a clearer upper and middle portion. This is because the chickpea protein dispersions under these conditions contained a large number of insoluble protein particles, which settled to the bottom of the centrifuge tube under gravity, consistent with their low solubility. The chickpea protein dispersions in Examples 1-3 did not show stratification; the protein dissolved well in the aqueous solution, exhibiting the most uniform dispersion. This further demonstrates that highly soluble chickpea protein dispersions can be successfully prepared through heat-combined high-pressure homogenization and L-Arg treatment.

[0083] from Figure 7 As can be seen, in Comparative Example 1, the chickpea protein dispersion exhibits irregular large clumps, which may be due to protein aggregation. Figures (B)-(C) show that the number of large aggregates in the chickpea protein dispersion is significantly reduced after high-pressure homogenization. After high-pressure homogenization and L-Arg treatment, no large particle aggregates were observed in the chickpea protein dispersion, but the particle distribution was still not uniform. The chickpea protein dispersion treated with heat, high-pressure homogenization, and L-Arg showed the most uniform, dense, and consistent distribution of small particles, indicating that the combined treatment can maximally decompose chickpea protein aggregates. This is beneficial for increasing the contact area between protein and water molecules, thereby significantly improving solubility.

[0084] from Figure 8 It can be seen that the chickpea protein dispersion treated with heat and high pressure homogenization combined with L-Arg achieved a minimum particle size of approximately 220 nm, significantly lower than that of comparative examples 1-6. This indicates that the combined treatment synergistically reduces the particle size of the chickpea protein dispersion, consistent with the results observed by laser confocal scanning microscopy. This is likely because heat and high pressure homogenization promotes the stretching of protein molecules and the exposure of active groups, creating favorable conditions for the binding of L-Arg to protein molecules. L-Arg can inhibit aggregation by enhancing the electrostatic repulsion on the surface of protein molecules, thereby further accelerating the decomposition of large molecular aggregates. The reduction in particle size facilitates the contact between protein and water molecules, thus improving solubility, which is also corroborated by the solubility results.

[0085] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high solubility chickpea protein dispersion, characterized by The method comprises the following steps: (1) dispersing chickpea protein powder in deionized water to form a chickpea protein dispersion with a certain concentration, adjusting the pH to neutral, stirring thoroughly, and standing overnight to fully hydrate the chickpea protein; (2) performing water bath heating treatment on the chickpea protein dispersion obtained in (1); (3) performing high-pressure homogenization treatment on the chickpea protein dispersion after water bath heating treatment; (4) adding an alkaline amino acid to the chickpea protein dispersion after high-pressure homogenization treatment, stirring thoroughly, and obtaining a uniform modified chickpea protein dispersion; (5) standing the modified chickpea protein dispersion obtained in (4) overnight to obtain a high-solubility chickpea protein dispersion with a solubility of ≥ 85%; In step (1), the mass fraction of the chickpea protein dispersion is 5.0%; In step (2), the heat treatment conditions are: heating temperature 80-100 ℃, heating time 30-60 min; In step (3), the high-pressure homogenization treatment conditions are: homogenization pressure 60-100 MPa, homogenization times 2-4 times; In step (4), the alkaline amino acid is L-Arg, and the addition mass fraction is 0.5-1.0%.

2. The method for preparing the highly soluble chickpea protein dispersion according to claim 1, characterized in that: In step (1), the pH is adjusted by HCl and / or NaOH.

3. The method for preparing the highly soluble chickpea protein dispersion according to claim 1, characterized in that: In step (1), the stirring conditions are magnetic stirring at a speed of 600 rpm at 25 ℃ for 2-2.5 h.

4. The method for preparing the highly soluble chickpea protein dispersion according to claim 1, characterized in that: In step (1), the standing temperature is 4 ℃.

5. The method for preparing the highly soluble chickpea protein dispersion according to claim 1, characterized in that: In step (4), the stirring conditions are magnetic stirring at a speed of 600 rpm at 25 ℃ for 2-2.5 h.

6. The method for preparing the highly soluble chickpea protein dispersion according to claim 1, characterized in that: In step (5), the standing conditions are the same as in step (1).

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