A method for efficiently preparing high-foaming chickpea protein isolate by pulsed electric field

Abstract

The method discloses a method for efficiently preparing high-foaming chickpea protein isolate by a pulsed electric field, and belongs to the technical field of deep processing of food protein. The method uses a high-field pulsed electric field technology, and adjusts the medium conductivity by using a saturated calcium chloride solution to process the chickpea protein isolate. The electric field strength is 50-70 kV / cm, the frequency is 100-300 Hz, the pulse width is 6-10 mu s, the sample processing time is 3-6 min, and the conductivity is adjusted to 400-600 mu S / cm. The space structure of the high-foaming chickpea protein isolate obtained by the method is unfolded, the hydrophobic group is exposed, the protein structure is stable, and the foaming capacity is increased by 8.4 times compared with that of the original chickpea protein isolate. The method has remarkable effects, is green, non-toxic, simple to operate, and can be carried out at room temperature throughout the whole process. The processing process is time-saving and low in energy consumption, has good food processing application feasibility, and greatly expands the practical application of the isolated protein of miscellaneous beans in the field of foamy food.

Description

TECHNICAL FIELD

[0001] The present application relates to high-foaming ability of mixed bean protein, in particular to a method for efficiently preparing high-foaming ability of chickpea protein based on pulsed electric field, belonging to the technical field of food protein deep processing. BACKGROUND

[0002] Foam is a dispersion system formed by insoluble gas dispersed in liquid or molten solid, and the volume fraction of the internal phase gas is greater than 90%. In the production of foam-like foods such as ice cream, cakes, and butter, air bubbles can give the food ideal texture and unique properties, and are also an important factor in measuring the quality of the food. However, foam does not form spontaneously, and a large amount of surface active substances with amphiphilic properties, i.e. foaming agents, must be provided to maintain the stable dispersion state of the air bubbles on the basis of external mechanical action. Common chemical foaming agents with good performance, such as sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether sodium sulfate, and mono-diglycerides, are limited in use in the field of food processing due to their irritant and safety issues. Therefore, the food field tends to choose natural components of food origin as foaming agents, such as protein foaming agents.

[0003] Protein foaming agents can be divided into animal protein foaming agents and plant protein foaming agents according to the source of the protein. Compared with animal proteins, plant proteins have the advantages of environmental friendliness, low economic cost, and high health benefits. Among them, chickpea, as the third largest legume crop in the world, has attracted much attention due to its high nutritional value. Chickpea protein (CP) isolated from chickpea contains a large amount of essential amino acids for the human body, and has high protein digestibility and bioavailability; compared with soybean, chickpea is a mixed legume crop, and has low content of anti-nutritional ingredients and allergens, and higher nutritional value, and is theoretically a high-quality food ingredient with wide application potential. However, in the actual production process, commercial chickpea protein is treated under extreme conditions, and denaturation and aggregation occur to different degrees, the protein spatial structure is destroyed, and the hydrophobic group is folded inward, resulting in a significant reduction in the foaming ability of commercial CP, which generally cannot meet the production needs of foam-like foods. Therefore, how to green and efficiently prepare high-foaming ability of CP, improve the foaming ability of commercial CP, and improve its functional properties, is of great importance to expand the application of chickpea in the field of foam-like food processing, and is also an important problem to be solved in this field.

[0004] The prior art methods for improving the foaming property of proteins mainly include enzymatic hydrolysis, high-temperature heating and chemical modification. Chinese patent application CN101011101A discloses a method for improving the foaming property of soybean protein, which comprises adding a complex enzyme composed of rice koji protease, trypsin and papain into soybean protein isolate, and then performing stirring, centrifugation, concentration and freeze-drying to obtain the hydrolyzed soybean protein isolate, wherein the foaming property of the hydrolyzed soybean protein isolate is improved by 83.3% compared with that of the untreated soybean protein isolate. Chinese patent application CN108782944A discloses a method for improving the foaming property and foam stability of whey protein concentrate, which comprises heating the whey protein concentrate at a high temperature, mixing the heated whey protein concentrate with unheated whey protein concentrate, and then heating the mixture at a high temperature under acidic conditions, so that the foaming capacity of the obtained whey protein concentrate fiber polymer is improved by 47.73%-59.09% compared with that of the untreated whey protein concentrate. Chinese patent CN104957356B discloses a method for improving the foaming property of egg white protein, which comprises adding glucose into the egg white protein and heating, so that the foaming property of the modified egg white protein is improved by 24.7%.

[0005] However, the above prior art methods still have certain limitations.

[0006] (1) The enzymatic hydrolysis method is uncontrollable, and it is difficult to achieve a better reaction endpoint because of the over-hydrolysis of enzymes. Moreover, the cost of biological enzyme preparation is high, and the method has high cost.

[0007] (2) The high-temperature heating method has high energy consumption and low reaction efficiency, and the denaturation and aggregation of proteins caused by high temperature treatment can further deteriorate the functional properties of proteins.

[0008] (3) The chemical modification method needs to introduce other substances into the protein system, which has many side reactions, complex products, high separation and purification difficulty, and limited improvement effect on the foaming property of proteins.

[0009] (4) The above prior art methods do not improve the foaming property of chickpea protein isolate, and the methods are not specific for the present application. SUMMARY

[0010] The present application aims to overcome the shortcomings and deficiencies of the prior art, and provide an efficient preparation technology for high-foaming chickpea protein isolate with high foaming capacity, high purity, easy separation and other advantages.

[0011] The present application is realized by the following technical solutions.

[0012] A method for efficiently preparing high-foaming chickpea protein isolate by pulsed electric field, comprising the following steps:

[0013] (1) Dissolve the chickpea protein powder in distilled water, fully dissolve, add saturated calcium chloride solution to adjust the solution conductivity to 400-600uS / cm, and obtain a chickpea protein solution;

[0014] (2) Pump the chickpea protein solution into the pulse electric field treatment chamber through a flow pump, set the electric field strength of the pulse treatment system to 50-70kV / cm, the frequency to 100-300Hz, the pulse width to 6-10μs, and the treatment time to 3-6min, to obtain the chickpea protein treated by the pulse electric field;

[0015] (3) Perform water dialysis on the chickpea protein treated by the pulse electric field in a low-temperature environment at 4-8℃ for 48-72h, and perform vacuum freeze-drying to obtain the high-foaming chickpea protein isolate.

[0016] To further achieve the purpose of the application, preferably, the mass-volume ratio of the chickpea protein powder to distilled water is 1:8-1:10, with the mass unit being gram and the volume unit being milliliter.

[0017] Preferably, the fully dissolving is performed by using a 50-60℃ water bath heating combined with mechanical stirring, and the stirring time is 2-3h.

[0018] Preferably, the solution conductivity in step (1) is adjusted to 500-550uS / cm.

[0019] Preferably, the flow rate of the flow pump in step (2) is controlled to 30-60mL / min.

[0020] Preferably, the electric field strength of the pulse treatment system is 60-70kV / cm.

[0021] Preferably, the frequency of the pulse treatment system is 250-300Hz.

[0022] Preferably, the pulse width of the pulse treatment system is 8-10μs.

[0023] Preferably, the treatment time of the pulse treatment system is 5-6min.

[0024] Preferably, the dialysis bag used for dialysis has a specification of 3500Da, the pre-freezing temperature of the vacuum freeze-drying is-80℃, and the freeze-drying time is 48h.

[0025] Compared with the prior art, the application has the following advantages and beneficial effects:

[0026] (1) The pulse electric field treatment technology selected by the present application is a non-thermal processing physical technology, which has the advantages of green, non-toxic, uniform treatment, controllable process, simple operation and the like compared with the existing technology biological method and chemical method, and the entire pulse electric field treatment process is extremely short, only 5 minutes.

[0027] (2) The method of the present application can be carried out at room temperature throughout the operation process, without introducing other impurities, and the conditions are mild and no side reactions are generated, so that the product does not need to be separated and purified, and has good feasibility for food industry processing application.

[0028] (3) The method of the present application significantly improves the pulse electric field treatment effect by using a specific calcium salt saturated solution to adjust the system conductivity, and the calcium ion can effectively induce the unfolding of the commercial protein aggregation structure and inhibit the reaggregation of the unfolded protein molecules, thereby improving the amphiphilic property of the protein and significantly improving the foaming property of the treated protein, and the high-foaming CP obtained has a maximum foaming capacity of 8.4 times higher than that of the original commercial CP, which is higher than most of the existing patent technologies.

[0029] (4) The high-foaming CP obtained by the present application provides a breakthrough technical guidance for the common problem of poor functional properties of commercial plant proteins, especially expanding the practical application of mixed bean plant proteins in the field of foam-like foods, and has strong practical significance. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a visual physical diagram of the foaming difference of Examples 1, 3, 5 and Comparative Examples 1-3.

[0031] Figure 2 It is the influence of the electric field strength of different pulse electric fields containing Examples 1, 3, 5 and Comparative Examples 1, 2 on the foaming property of chickpea protein isolate.

[0032] Figure 3 It is the endogenous fluorescence spectrum graph of Examples 1, 3, 5 and Comparative Examples 1, 2 at 280 nm. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the specific implementation manner and examples of the present application will be further provided below. It should be understood that the specific implementation manner described herein is only used to explain the present application, and is not used to limit the present application, and the described examples are only a part of the examples of the present application, not all examples.

[0034] The examples of the present application are related to the test method as follows:

[0035] I. Determination method of foaming property of protein solution:

[0036] A 1% (w / v) chickpea protein isolate solution 20 mL was placed in a glass cylinder with a diameter of 3 cm, foamed using a T25 homogenizer (IKA, Germany) at a speed of 8000 rpm for 2 min, and then immediately poured into a 50 mL graduated cylinder. The foaming capacity (FA) was calculated according to the following formula:

[0037]

[0038] V2 is the volume after foaming for 2 min. The entire experiment was repeated three times at room temperature (25 ± 0.2°C), and the results were averaged.

[0039] II. Method for measuring the endogenous fluorescence intensity of the protein solution:

[0040] A 1% (w / v, g / mL) chickpea protein isolate solution 0.9 mL was weighed and placed in a 10 mL centrifuge tube, 8.1 mL of distilled water was added, and the mixture was mixed uniformly using a vortex shaker to obtain a 1 mg / mL chickpea protein isolate solution. The endogenous fluorescence spectrum of the chickpea protein isolate solution was recorded using an RF-6000 fluorescence spectrophotometer (Shanghai Nanjing Technology Co., Ltd.) at an emission wavelength of 298-400 nm, an excitation wavelength of 280 nm, a scanning speed of 600 nm / min, and an excitation and emission slit width of 3 nm.

[0041] III. Method for measuring the secondary structure of the protein:

[0042] A 1% (w / v, g / mL) chickpea protein isolate solution was diluted with distilled water to 0.1 mg / mL and added to a cuvette. The spectral information of the protein solution at 190 nm-250 nm was measured using a J-1500 circular dichroism spectrometer (JASCO Co., Ltd., Japan), and the proportion of the secondary structure of the protein was calculated.

[0043] The following examples and comparative examples use samples that are chickpea protein isolate powder, purchased from Yantai Shuangta Food Co., Ltd., with a protein purity of more than 99.5%.

[0044] To address the problems of high cost, high energy consumption, difficult product separation, limited improvement effect (foaming capacity improvement rate not more than 100%), and the like, the present application features a processing method based on high-voltage pulsed electric field technology to prepare a high-foaming capacity commercial CP. The method is uniform, adjustable, controllable, green, efficient, and single-product, and is suitable for modern food industry production needs.

[0045] It should be noted that as a new non-thermal processing technology, pulse electric field technology has been reported in the modification of proteins and has shown a wide range of application prospects. Studies have shown that pulse electric field technology can induce changes in protein structure, thereby improving some of its functional properties: for example, researchers use pulse electric field treatment to passivate or activate papain, pepsin, peroxidase, etc.; egg white protein and beta-lactoglobulin will be partially denatured under the treatment of 12.5kV / cm pulse, inducing the exposure of hydrophobic groups inside the protein structure, with stronger bioavailability; under the treatment of pulse electric field, the structure of ovalbumin and bovine serum albumin is unfolded, and protein aggregates can be formed through hydrophobic interaction and disulfide bond. In the improvement of the functional properties of proteins by pulse electric field treatment, there are fewer reports on the research of protein foaming, mainly focusing on food proteins with excellent foaming properties, for example, Zhao Wei et al. found that the foaming property of ovalbumin can be improved by 15%-30% and the foam stability can be improved by 35%-43% under the treatment of 25-35kV / cm pulse electric field for 300μs; Wang Rui et al. found that the foaming property of soy protein solution can be improved by 20% by using 5-10kV / cm pulse electric field alone. However, the effect of pulse electric field technology in improving the foaming property of proteins reported in the existing reports is relatively limited, which is considered to be mainly limited by the low conductivity of the treatment medium and the low voltage input of the electric field equipment.

[0046] It should be emphasized that compared with ovalbumin, egg white protein and soy protein which have high foaming properties, chickpea protein shows almost no foaming property (the foaming capacity of 1mg / mL CP solution is only about 10%). This is due to the uniqueness of the composition of CP protein structure (50-60% globulin, 20%-25% glutelin, 10% albumin), which is different from egg white protein mainly composed of water-soluble albumin and common legume seed protein mainly composed of salt-soluble globulin. The relatively high content of glutelin in CP is prone to aggregation in the gas-liquid-gas interface system, which destroys the interface balance and leads to low foaming capacity of CP. Currently, there is no report on the use of pulse electric field technology to treat chickpea protein isolate and improve its foaming property.

[0047] The present application uses high-voltage pulse electric field technology to treat CP, and through the regulation of conductivity by specific saturated calcium salt solution and the instantaneous action of high-voltage pulse electric field, the protein structure is unfolded, the aggregation of CP on the gas-liquid interface is reduced, and the amphiphilicity of CP is balanced, thereby efficiently preparing high-foaming CP in a green way and widening the application of mixed bean protein isolate as a functional aid in the field of foam food processing.

[0048] Specifically, the application uses specific pulsed electric field treatment conditions, mainly including high-voltage pulsed electric field intensity of 50-70 kV / cm, high duty cycle narrow pulse width of 6-10 s, short treatment time of 3-6 min, and using saturated calcium chloride solution to adjust to a suitable medium conductivity of 500-550 uS / cm, to modify the gas / liquid interface properties of chickpea protein isolate. Test results show that the fluorescence intensity of the commercial CP solution treated by the application is greatly improved, and the detectable tyrosine and other hydrophobic chromogenic amino acids in the protein solution are significantly increased, indicating that more protein hydrophobic groups are exposed under the action of the electric field; at the same time, the proportion of alpha-helix in the protein secondary structure decreases, and other structures such as beta-sheet, beta-turn and random coil increase, and the protein behaves more stably under the action of the pulsed electric field, that is, the protein will not easily form aggregates with poor interfacial properties through hydrophobic interaction. When an ultra-high strength external electric field is applied, by adjusting the saturated calcium salt solution to a suitable conductivity, a strong current passes through the medium to act on the protein instantaneously, the dipole moment between the protein molecules changes, the local electrostatic interaction and intermolecular force between the polypeptide chains and the polypeptide chains are destroyed, thereby causing the spatial conformation of the protein to change; at the same time, the unique weak gold property of calcium ions makes it difficult for them to form water and ions in the aqueous system, so they are more likely to be enriched around the protein molecules through electrostatic interaction, further destroying the electrostatic balance between and within the protein molecules, and inhibiting the formation of protein aggregates; in addition, the metal ions enriched around the protein have a synergistic effect of locally amplifying the electric field effect under the action of the pulsed electric field, significantly improving the effect of the pulsed electric field on the chickpea protein-calcium ion binding site. Therefore, the structure of CP is fully unfolded under the action of high-voltage pulsed electric field and calcium salt regulation, exposing the originally embedded hydrophobic region to form a stable folded protein structure, so that the hydrophobic groups and hydrophilic groups exposed at the gas / liquid interface of the protein reach a balance, which can significantly improve the amphiphilicity of commercial CP and better adsorb on the gas / liquid interface to stably form protein foam. The high-foaming CP obtained by the method of the application has an 8.4-fold increase in foaming capacity compared to the original commercial CP. The method of the application develops the nutritionally high and high-yield almost non-foaming chickpea protein into high-foaming chickpea protein isolate, which has important practical value.

[0049] Example 1

[0050] A method for efficiently preparing high-foaming chickpea protein isolate by pulsed electric field, specifically comprising the following steps:

[0051] (1) Mix chickpea protein isolate powder and distilled water at a ratio of 1:10 (w / v, g / mL), mechanically stir for 3 hours under the condition of 60°C water bath heating to make the protein fully dissolved, and add appropriate amount of saturated calcium chloride solution to adjust the conductivity of the protein solution to 500 uS / cm.

[0052] (2) The CP solution treated in step (1) is pumped into a pulse electric field treatment chamber, the electric field strength of the pulse treatment system is set to 50 kV / cm, the frequency is 250 Hz, the pulse width is 8 μs, and the sample treatment time is 5 min.

[0053] (3) The CP solution treated in step (2) is dialyzed in a 4°C environment for 48 h, and then vacuum freeze-dried to obtain the sample of Example 1.

[0054] According to the determination method of the foaming property of the protein solution, the foaming property of the CP obtained in this embodiment 1 is 69%, which is 5.9 times higher than that of the initial CP (10%).

[0055] Example 2

[0056] A method for efficiently preparing high-foaming chickpea protein isolate by pulse electric field, specifically comprising the following steps:

[0057] (1) Chickpea protein isolate powder is mixed with distilled water at a ratio of 1:10 (w / v, g / mL), mechanically stirred at 60°C water bath heating condition for 3 hours to fully dissolve the protein, and an appropriate amount of calcium chloride saturated solution is added to adjust the conductivity of the protein solution to 400 uS / cm.

[0058] (2) The CP solution treated in step (1) is pumped into a pulse electric field treatment chamber, the electric field strength of the pulse treatment system is set to 60 kV / cm, the frequency is 100 Hz, the pulse width is 6 μs, and the sample treatment time is 3 min.

[0059] (3) The CP solution treated in step (2) is dialyzed in a 4°C environment for 48 h, and then vacuum freeze-dried to obtain the sample of Example 2.

[0060] According to the determination method of the foaming property of the protein solution, the foaming property of the CP obtained in this embodiment 2 is 75%, which is 6.5 times higher than that of the initial CP (10%).

[0061] Example 3

[0062] A method for efficiently preparing high-foaming chickpea protein isolate by pulse electric field, specifically comprising the following steps:

[0063] (1) Chickpea protein isolate powder is mixed with distilled water at a ratio of 1:10 (w / v, g / mL), mechanically stirred at 60°C water bath heating condition for 3 hours to fully dissolve the protein, and an appropriate amount of calcium chloride saturated solution is added to adjust the conductivity of the protein solution to 500 uS / cm.

[0064] (2) The CP solution treated in step (1) is pumped into a pulsed electric field treatment chamber, the electric field strength of the pulse treatment system is set to 60 kV / cm, the frequency is 250 Hz, the pulse width is 8 μs, and the sample treatment time is 5 min.

[0065] (3) The CP solution treated in step (2) is dialyzed in a 4℃ environment for 48 h, and then vacuum freeze-dried to obtain the sample of Example 3.

[0066] According to the determination method of the foaming property of the protein solution, the foaming property of the CP obtained in this embodiment 3 is 90%, which is 8 times higher than that of the initial CP (10%).

[0067] Example 4

[0068] A method for efficiently preparing high-foaming chickpea protein isolate by pulsed electric field, specifically comprising the following steps:

[0069] (1) Chickpea protein isolate powder is mixed with distilled water at a ratio of 1:10 (w / v, g / mL), and mechanically stirred at 60℃ water bath heating condition for 3 hours to fully dissolve the protein. During the stirring process, an appropriate amount of calcium chloride saturated solution is added to adjust the conductivity of the protein solution to 600 uS / cm.

[0070] (2) The CP solution treated in step (1) is pumped into a pulsed electric field treatment chamber, the electric field strength of the pulse treatment system is set to 65 kV / cm, the frequency is 300 Hz, the pulse width is 10 μs, and the sample treatment time is 6 min.

[0071] (3) The CP solution treated in step (2) is dialyzed in a 4℃ environment for 48 h, and then vacuum freeze-dried to obtain the sample of Example 4.

[0072] According to the determination method of the foaming property of the protein solution, the foaming property of the CP obtained in this embodiment 4 is 92.5%, which is 8.25 times higher than that of the initial CP (10%).

[0073] Example 5

[0074] A method for efficiently preparing high-foaming chickpea protein isolate by pulsed electric field, specifically comprising the following steps:

[0075] (1) Chickpea protein isolate powder is mixed with distilled water at a ratio of 1:10 (w / v, g / mL), and mechanically stirred at 60℃ water bath heating condition for 3 hours to fully dissolve the protein. During the stirring process, an appropriate amount of calcium chloride saturated solution is added to adjust the conductivity of the protein solution to 500 uS / cm.

[0076] (2) The CP solution treated in step (1) was pumped into the pulse electric field treatment chamber, and the electric field strength of the pulse treatment system was set to 70 kV / cm, the frequency was 250 Hz, the pulse width was 8 μs, and the sample treatment time was 5 min.

[0077] (3) The CP solution treated in step (2) was dialyzed in a 4℃ environment for 48 h, and then vacuum freeze-dried to obtain the sample of Example 5.

[0078] According to the determination method of protein solution foaming property, the foaming property of the CP obtained in Example 5 was 94%, which was 8.4 times higher than that of the initial CP (10%).

[0079] Comparative Example 1

[0080] The specific steps of the present comparative example are as follows:

[0081] (1) Chickpea protein isolate powder was mixed with distilled water at a ratio of 1:10 (w / v, g / mL), and mechanical stirring was carried out at 60℃ water bath heating condition for 3 hours to fully dissolve the protein.

[0082] (2) The CP solution of step (1) was dialyzed in a 4℃ environment for 48 h, and then vacuum freeze-dried to obtain the sample of Comparative Example 1.

[0083] The present comparative example did not undergo pulse electric field treatment and did not add calcium chloride saturated solution to adjust the conductivity. The CP of Comparative Example 1 was the initial CP, and the foaming property was determined to be 10%.

[0084] Comparative Example 2

[0085] The specific steps of the present comparative example are as follows:

[0086] (1) Chickpea protein isolate powder was mixed with distilled water at a ratio of 1:10 (w / v, g / mL), and mechanical stirring was carried out at 60℃ water bath heating condition for 3 hours to fully dissolve the protein. During the stirring process, an appropriate amount of calcium chloride saturated solution was added to adjust the conductivity of the protein solution to 500 uS / cm.

[0087] (2) The CP solution treated in step (1) was pumped into the pulse electric field treatment chamber, and the electric field strength of the pulse treatment system was set to 20 kV / cm, the frequency was 250 Hz, the pulse width was 8 μs, and the sample treatment time was 5 min.

[0088] (3) The CP solution treated in step (2) was dialyzed in a 4℃ environment for 48 h, and then vacuum freeze-dried to obtain the sample of Comparative Example 2.

[0089] Comparative Example 2 is a low electric field strength treatment condition control. According to the method for determining the foaming property of a protein solution, the foaming property of the CP obtained in Comparative Example 2 was 12.5%, which was only increased by 25% compared to the initial CP (10%).

[0090] Comparative Example 3

[0091] The specific steps of the comparative example are as follows:

[0092] (1) The chickpea protein isolate powder was mixed with distilled water at a ratio of 1:10 (w / v, g / mL) and mechanically stirred at 60°C in a water bath for 3 hours to fully dissolve the protein.

[0093] (2) The CP solution treated in step (1) was pumped into a pulse electric field treatment chamber, and the electric field strength of the pulse treatment system was set to 50 kV / cm, the frequency was 250 Hz, the pulse width was 8 μs, and the sample treatment time was 5 min.

[0094] (3) The CP solution treated in step (2) was dialyzed at 4°C for 48 h, and then vacuum freeze-dried to obtain the Comparative Example 3 sample.

[0095] Comparative Example 3 did not add a saturated calcium chloride solution to adjust the conductivity, and the conductivity of the original protein solution was measured to be 84.58 uS / cm. The foaming property of the CP in Comparative Example 3 was measured to be 25%, which was 1.5 times higher than that of the initial CP (10%).

[0096] Figure 1 A visual physical diagram of the foaming property differences of the inventive examples and comparative examples. In Example 1, the electric field strength of the pulse electric field was 50 kV / cm and the frequency was 250 Hz, and the foaming property of the CP solution was 69%, which was 5.9 times higher than that of Comparative Example 1. Under the same electric field conditions, the foaming capacity of Comparative Example 3, which did not add a saturated calcium chloride solution to adjust the conductivity, was only increased by 1.5 times compared to Comparative Example 1, indicating that adding a saturated calcium chloride solution to adjust the conductivity can further improve the foaming capacity of the CP. In Example 5, the electric field strength of the pulse electric field was 70 kV / cm and the frequency was 250 Hz, and the foaming capacity of the CP solution treated under this condition was significantly higher than that of the other treatments, and the foaming capacity was increased by 8.4 times compared to Comparative Example 1, indicating that under the electric field strength treatment of 50-70 kV / cm, the foaming property of the CP solution will increase with the increase of the input energy of the pulse electric field.

[0097] Figure 2 The foaming property differences of the CP solution after treatment under different electric field strength conditions, Figure 2The several groups of protein solutions shown in the processing, in addition to the electric field intensity of the pulse electric field is different, other process conditions are the same as example 1. As can be seen from the figure, when the electric field intensity of the pulse electric field is 20kV / cm (i.e. comparative example 2), the foaming property of the CP solution is 12.5%, which is only increased by 25% compared with the original CP, indicating that under the lower electric field intensity, the processing mode of the present technology cannot achieve better improvement effect; when the electric field intensity of the pulse electric field is 50kV / cm, the foaming property of the CP solution is 69%, which is increased by 5.9 times compared with the original CP, which has a significant improvement effect; when the electric field intensity of the pulse electric field is increased to 60-70kV / cm, the foaming amount of the CP solution treated under this condition is the largest, also close to the processing saturation, and the foaming capacity is increased by 8.4 times compared with comparative example 1. Therefore, the processing condition of the electric field intensity is preferably 60-70kV / cm.

[0098] Figure 3 For the fluorescence spectrum of the inventive examples and comparative examples, the maximum fluorescence intensity wavelength of comparative example 1 is 324nm, and the fluorescence intensity is the lowest; the fluorescence intensity of comparative example 2, example 1, example 3, example 5 is improved in turn, and the maximum emission wavelength appears red shift. This shows that the pulse electric field treatment leads to the unfolding of the structure of the protein, and the tyrosine and other hydrophobic amino acids located inside the protein are gradually exposed to the aqueous solution, thereby the amphiphilicity of the CP is significantly improved, and then the foaming capacity is greatly improved, and the improvement amplitude increases with the increase of the electric field intensity of the pulse electric field in the range of 50-70kV / cm.

[0099] Table 1 is the difference of the secondary structure of the protein of the CP solution after being treated under different electric field intensity conditions, the protein solutions shown in table 1 are treated except that the electric field intensity of the pulse electric field is different, other process conditions are the same as example 1. As can be seen from the table, after the pulse electric field treatment, with the increase of the electric field intensity of the pulse electric field, the content of the α-helix of the protein is significantly reduced, and the content of the β-sheet, β-turn and random coil is increased.

[0100] Table 1

[0101]

[0102] Note: all tests in table 1 are consistent in process conditions except the electric field intensity of the pulse electric field.

[0103] The above has made a detailed description of the present application and described the examples, but the present application is not limited thereto, and those skilled in the art can obviously make various forms of changes and innovations according to the above description, as long as they are within the scope protected by the claims of the present application.

Claims

1. A method for efficiently preparing high foaming chickpea protein isolate by pulsed electric field, characterized in that It comprises the following steps: (1) Dissolve chickpea protein powder in distilled water, fully dissolve, add saturated calcium chloride solution to adjust the solution conductivity to 400-600 uS / cm, and obtain a chickpea protein solution; (2) Pump the chickpea protein solution into the pulse electric field treatment chamber through a flow pump, set the electric field strength of the pulse treatment system to 50-70 kV / cm, the frequency to 100-300 Hz, the pulse width to 6-10 μs, and the treatment time to 3-6 min, to obtain a pulse electric field treated chickpea protein; (3) Water dialyze the pulse electric field treated chickpea protein in a low temperature environment of 4-8℃ for 48-72 h, and obtain high-foaming chickpea protein isolate through vacuum freeze drying.

2. The method of claim 1, wherein the high foaming chickpea protein isolate is prepared by the pulsed electric field, and the method is characterized by, The mass-volume ratio of the chickpea protein powder to distilled water is 1:8-1:10, with the mass unit being gram and the volume unit being milliliter.

3. The method of claim 1, wherein the high foaming chickpea protein isolate is prepared by the pulsed electric field. The fully dissolving is achieved by using a 50-60℃ water bath heating combined with mechanical stirring, with the stirring time being 2-3 h.

4. The method of claim 1, wherein the high foaming chickpea protein isolate is prepared by the pulsed electric field. In step (1), the solution conductivity is adjusted to 500-550 uS / cm.

5. The method of claim 1, wherein the pulse electric field is applied at a voltage of 0.5 to 2 kV, a current of 0.5 to 2 mA, a frequency of 100 to 1,000 Hz, and a pulse width of 0.1 to 1 ms. In step (2), the flow rate of the flow pump is controlled to be 30-60 mL / min.

6. The method of claim 1, wherein the high foaming chickpea protein isolate is prepared by the method of pulse electric field, and the method is characterized by, The electric field strength of the pulse treatment system is 60-70 kV / cm.

7. The method of claim 1, wherein the high foaming chickpea protein isolate is prepared with high efficiency by pulsed electric field. The frequency of the pulse treatment system is 250-300 Hz.

8. The method of claim 1, wherein the high foaming chickpea protein isolate is prepared with high efficiency by pulsed electric field. The pulse width of the pulse treatment system is 8-10 μs.

9. The method of claim 1, wherein the high foaming chickpea protein isolate is prepared with high efficiency by pulsed electric field. The treatment time of the pulse treatment system is 5-6 min.

10. The method of claim 1, wherein the high foaming chickpea protein isolate is prepared with high efficiency by pulsed electric field. The dialysis bag used for dialysis has a specification of 3500 Da, the pre-freezing temperature of vacuum freeze drying is-80℃, and the freeze drying time is 48 h.

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