A high-performance potato protein continuous modification and purification preparation process

Abstract

The application discloses a kind of high-performance potato protein continuous modification purification preparation processes, belong to the field of potato protein extraction, solve the problem of low purity, low solubility of potato protein.Preparation process: the impurities in potato starch processing separation juice water are separated, and potato protein juice water is obtained;Potato protein juice water is heated to obtain potato wet protein;Potato wet protein is transferred to constant-temperature reaction tank containing alkaline solution to obtain potato protein alkali solution;The pH of potato protein alkali solution is adjusted to 4-6, so that the potato protein is fully precipitated, and the protease hydrolysate is obtained by protease hydrolysis and spray drying;Resuspend with water to obtain purified potato protein;Ultrasonic assisted method is used to modify potato protein;Spray drying.The potato protein prepared by the application is uniform in particle size, has good emulsifying property, good color, high purity, high nutritional value and greatly enhanced solubility, and can be applied to food processing to improve the utilization value of potato protein.

Description

Technical Field

[0001] This invention belongs to the field of potato protein extraction, specifically relating to a high-performance continuous modification and purification process for potato protein. Background Technology

[0002] Potato protein is a high-quality plant protein, containing a variety of essential amino acids, such as lysine, in high amounts, giving it high nutritional value. This makes potato protein a promising candidate for applications in food and other fields. Furthermore, potato protein has relatively low allergenicity, making it a potential alternative to soy protein. Adding potato protein to foods such as bread, noodles, dairy products, and meat products can improve their nutritional value and quality.

[0003] There are various methods for extracting potato protein, each with its own advantages and disadvantages. Ultrafiltration membranes utilize selective separation to separate potato protein from other impurities. This method can improve protein purity to some extent, but membrane fouling is a significant problem, and separation efficiency is affected by membrane pore size and operating conditions. Adding proteases hydrolyzes other components in potatoes, releasing potato protein. This method can improve protein extraction rate and purity, and operates under mild conditions with minimal damage to protein structure. However, enzyme costs are high, and enzymatic hydrolysis conditions require optimization. In recent years, Solanic in the Netherlands and Kemin in the United States have achieved the industrial-scale utilization of high molecular weight active potato protein for food and low molecular weight active potato protein for pharmaceuticals, becoming pioneers in the industrial production of food-grade / pharmaceutical-grade potato protein. However, expanded bed adsorption technology, a key technology for separating natural active proteins from potato starch processing juice, is difficult to industrialize due to the high cost of imported packing materials. Furthermore, expanded bed adsorption technology is currently subject to embargoes by Western countries as a technological challenge. Currently, thermal flocculation is widely used for extracting potato protein. Although traditional thermal flocculation achieves high protein recovery rates, the protein undergoes irreversible denaturation, its spatial structure is destroyed, and it loses its biological activity. Furthermore, the resulting product is dark in color, bitter in taste, and has low solubility, making it unsuitable for food and pharmaceuticals, and thus only used for low-value-added products. Moreover, the traditional thermal flocculation method yields low-cost potato protein (6000 yuan / ton), leading to its limited use in feed or fertilizer, resulting in significant waste and severely limiting its application prospects. Therefore, improving the purity and concentration of potato protein extracted by thermal flocculation has become a challenge in the industry. Summary of the Invention

[0004] The purpose of this invention is to provide a continuous modification and purification process for high-performance potato protein, which utilizes an ultrasonic-thermal assisted alkali dissolution and acid precipitation method to solve the problems of low purity and low solubility of potato protein, thereby achieving continuous production of high-performance potato protein.

[0005] The technical solution of this invention is: a continuous modification and purification process for preparing high-performance potato protein, comprising the following steps: S1. Impurity Removal: Potato starch is processed and separated into juice and impurities (small starch particles, fine fibers, and residues) using a horizontal centrifuge or a four-stage hydrocyclone to obtain potato protein juice. By utilizing the density difference between starch and protein, impurities and potato protein juice can be separated, reducing starch impurities from 1% to below 0.3%. S2. Protein extraction: The potato protein juice is heated to 100-110℃ using a steam heater and kept at the temperature for 10 min to denature the potato protein, break its spatial structure, and expose hydrophobic groups, thereby causing the protein to aggregate and precipitate. The precipitate is collected by centrifugation using a horizontal centrifuge to obtain low-purity potato wet protein. S3. Protein Purification and Modification: Wet potato protein was transferred to a constant-temperature reaction vessel containing an alkaline solution at 50-60℃ and reacted for 3 hours to remove impurity groups, yielding an alkaline potato protein solution. The pH of the alkaline potato protein solution was adjusted to 4-6 (near the isoelectric point) using HCl or citric acid, with continuous stirring to ensure complete precipitation of the potato protein. The residue was collected, hydrolyzed with protease, and then spray-dried to obtain the protease hydrolysate. After resuspending in water, the hydrolysate was homogenized in an elution tank at a water-to-hydrolysate volume ratio of 2-4:0.5. Centrifugation was performed, and this process was repeated 2-3 times to remove salts generated during the alkaline dissolution and acid precipitation process, reducing the salt concentration in the protein. The supernatant conductivity was increased to 50-500 μS / cm, yielding purified potato protein. Ultrasonic-assisted modification of the potato protein was then performed to increase its solubility. S4. Protein drying: After homogenizing the potato protein purified and modified in step S3, spray dry to obtain high-purity potato protein powder.

[0006] As a further improvement of the present invention, in step S2, the pH of the potato protein juice is adjusted to 4.5-5.5 (near the isoelectric point) before heating, so that the potato protein can flocculate and precipitate as much as possible.

[0007] As a further improvement of the present invention, in step S3, the mass ratio of the protein hydrolysate to the liquid is 2-4:0.5 when the protein hydrolysate is resuspended in water.

[0008] As a further improvement of the present invention, in step S3, the mass ratio of potato wet protein to alkaline solution is 1-1.5:0.5, the alkaline solution is NaOH or KOH, and the pH of the alkaline solution is 10-11.

[0009] As a further improvement of the present invention, in step S3, the pH of the potato protein alkaline solution is adjusted to 5.5. Under this condition, potato protein is more easily precipitated and the amount of protein precipitated is the largest.

[0010] As a further improvement of the present invention, in step S3, the ultrasonic frequency is set to 40 kHz, the ultrasonic time is 20 min, and the temperature is controlled at 45-55℃. Ultrasonic treatment may break some secondary bonds (such as hydrogen bonds and hydrophobic bonds) of protein molecules, resulting in a loose spatial structure, exposing more hydrophilic groups (such as hydroxyl, carboxyl, and amino groups), enhancing the interaction with water molecules (hydration), and thus improving solubility.

[0011] As a further improvement of the present invention, in step S3, the protease is a complex enzyme with an activity of 100,000 U-200,000 U, the mass concentration of the collected residue is 3%-5%, the pH value is adjusted to 8 during hydrolysis, the reaction temperature is 55°C, and the reaction time is 4 hours.

[0012] As a further improvement of the present invention, in step S4, the pH of the potato protein slurry is adjusted to 7 before spraying. This is because the dried potato protein powder is whiter when the pH is 7, and also because, considering food use, a pH of 7 avoids the isoelectric point of the potato protein, which can ensure that the protein is fully dissolved, has a delicate texture, and remains stable during storage, making it less prone to precipitation or denaturation.

[0013] As a further improvement of the present invention, in step S4, the concentration of potato protein slurry is controlled at 15% to 25%; the spray drying parameters are set as follows: inlet air temperature 150-180℃, outlet air temperature 80-85℃, 15-20 MPa, and drying time 20s.

[0014] As a further improvement of the present invention, in step S4, a homogenizer is used to break the potato protein particles to 30-150 mesh, which helps with subsequent spray drying and improves the solubility of the dried potato protein.

[0015] Potato protein is diluted with an alkaline solution and reacted at a constant temperature for a certain period of time to promote the separation of glycans from the protein. This hydrolyzes and breaks the chemical bonds connecting the glycans and protein in the potato protein, such as O-glycosidic bonds or N-glycosidic bonds, causing the glycans to detach from the protein, resulting in deglycosylated protein. Additionally, the alkaline solution reacts with the glycosidic alkaloids contained in the potato protein. The alkaline solution catalyzes the hydrolysis of the glycosidic bonds in the glycosidic alkaloids. Under alkaline conditions, hydroxide ions attack the glycosidic bonds, causing them to break and separating the glycosyl group from the aglycone.

[0016] This invention uses thermal flocculation to extract protein from potato processing juice, and combines this with a thermal synergistic alkali dissolution and acid precipitation method to purify potato protein. Compared with existing technologies, this invention has the following advantages: 1. Existing methods for extracting potato protein using thermal flocculation, due to their low purity (50%-75%), limit their use to feed and fertilizer. This invention combines thermal flocculation with alkali dissolution and acid precipitation for protein extraction and purification, achieving a protein purity of over 95% and a protein recovery rate of over 80%. This significantly improves the protein extraction rate, bringing the potato protein to food-grade purity and enabling high-value utilization of potato protein. The potato protein prepared using this method exhibits uniform particle size, good emulsification properties, good color, high purity, high nutritional value, and significantly enhanced solubility, making it suitable for food processing and improving the utilization value of potato protein.

[0017] 2. The invention reduces the particle size of thermally flocculant proteins, decreases the exposure of hydrophobic groups and free thiol groups in thermally flocculant proteins, thereby improving solubility and partially restoring protein structure and function.

[0018] 3. This invention directly uses the wet protein extracted by thermal flocculation for purification by ultrasonic-thermal assisted alkali dissolution and acid precipitation, reducing the intermediate drying steps of using a hot air drying system and effectively reducing the drying cost of the protein; the purification of protein powder increases the high-value utilization of potato protein.

[0019] 4. The potato protein preparation process of this invention is simple, involves less investment in production system equipment, has low operating costs, and is pollution-free. It can be used for the extraction and purification of potato protein and is suitable for large-scale industrial continuous production. Attached Figure Description

[0020] Figure 1 These are morphological diagrams of the potato protein purification and modification process in Example 1 of this invention; Figure 2 This is a comparison chart of the appearance and solubility of potato protein powder prepared in Example 2 of the present invention with hot-coagulated protein, potato protein hydrolysate, and potato protein extracted by EBA method. Figure 3 This is a secondary structure analysis diagram of potato protein powder prepared in Example 2 of the present invention, thermally coagulated protein, potato protein hydrolysate, and potato protein extracted by EBA method. Figure 4 This is a particle size distribution and analysis diagram of potato protein powder prepared in Example 2 of the present invention, thermally coagulated protein, potato protein hydrolysate, and potato protein extracted by EBA method. Figure 5 These are atomic force microscopy images of the potato protein powder prepared in Example 2 of this invention, along with thermally coagulated protein, potato protein hydrolysate, and potato protein extracted by the EBA method. Figure 6 This is a comparison chart of the foaming properties of potato protein powder prepared in Example 2 of the present invention with those of thermally coagulated protein, potato protein hydrolysate, and potato protein extracted by EBA method. Figure 7 This is a comparison chart of the emulsifying properties of potato protein powder prepared in Example 2 of the present invention with those of thermally coagulated protein, potato protein hydrolysate, and potato protein extracted by EBA method. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments.

[0022] Example 1 A continuous modification and purification process for preparing high-performance potato protein includes the following steps: S1. Impurity removal: Impurities are removed from the potato starch juice using a four-stage hydrocyclone to obtain potato protein juice.

[0023] S2. Protein extraction: Adjust the pH of the potato protein juice to 5.5, then heat the potato protein juice to 110°C using a steam heater and maintain the temperature for 10 min to denature the potato protein, break its spatial structure, and expose hydrophobic groups, thereby causing the protein to aggregate and precipitate. Collect the precipitate by centrifugation using a horizontal centrifuge to obtain low-purity potato wet protein.

[0024] S3. Protein purification and modification: Wet potato protein was transferred to a constant-temperature reaction vessel containing an alkaline solution (0.1-0.3M NaOH), and the temperature was set at 60℃. The reaction was maintained at this temperature for 3 hours to remove impurity groups. (4000...) Centrifuge at 10 r / min for 10 min to obtain potato protein alkaline solution; adjust the pH of potato protein alkaline solution to 1-14 with HCl, stirring constantly to ensure complete precipitation of potato protein, collect the residue to obtain potato protein precipitates at different pH, hydrolyze with protease and spray dry to obtain protease hydrolysate. The protease used is a complex enzyme with an activity of 100,000 U-200,000 U, the mass concentration of the residue (potato protein precipitate) is 5%, the pH is adjusted to 8, the reaction temperature is 55℃, and the reaction time is 4 h. Resuspend with an equal volume of water and transfer to an elution tank for homogenization, centrifuge and precipitate, repeat this process 3 times for desalting until the conductivity of the supernatant reaches 400 μS / cm to obtain purified potato protein; modify potato protein using ultrasound-assisted method, with ultrasound frequency set at 40 kHz, ultrasound time at 20 min, and temperature controlled at 45℃.

[0025] S4. Protein Drying: The potato protein slurry purified and modified in step S3 is homogenized, and the potato protein particles are crushed to 120 mesh using a homogenizer. The concentration of the potato protein slurry is controlled at 20%, and the pH of the potato protein slurry is adjusted to 7. Spray drying is then carried out with the following parameters: inlet air temperature 160℃, outlet air temperature 85℃, 20 MPa, and drying time 20s, to obtain high-purity potato protein powder.

[0026] In step S3, during acid precipitation, the amount of potato protein precipitated at different pH levels was compared. 1g of the prepared potato protein powder was weighed and dissolved in 10ml of water. The color changes of the protein solution in water under different pH conditions were observed. After standing for 2 hours, the suspension characteristics of different potato protein powders were compared.

[0027] Figure 1 These are images showing the properties of potato protein during the purification and modification process in this embodiment. A shows the suspension of potato protein under different NaOH concentrations during alkali dissolution; the NaOH concentration is labeled on the bottle in the image. B shows the precipitation of potato protein at different pH values ​​during acid precipitation; the pH value is labeled on the bottle in the image. C shows the color change of the dried protein powder at different pH values; the pH value is labeled on the bottle in the image. Figure 1 As shown in Figure A, with increasing NaOH concentration, the potato protein precipitate gradually decreases while the solubility gradually increases. At 0.3M, the potato protein precipitate disappears, and the potato protein is completely dissolved. Figure 1 As shown in B, the precipitation of potato protein is greatest at pH 4-5, because 4-5 is the isoelectric point of potato protein. When pH < 4, the precipitation of potato protein gradually decreases as pH decreases; when pH > 6, the precipitation of potato protein gradually decreases as pH increases. Figure 1 As shown in B, at pH 1-2, potato protein is mostly dissolved, with relatively little suspended protein. At pH 3-5, potato protein powder exhibits the worst suspension properties, with most of the protein powder settling. At pH 6-7, potato protein powder exhibits the best suspension properties. Above pH 8, the suspended protein content gradually decreases with increasing pH. Figure 1 As shown in Figure C, during acid precipitation, the protein solution changes from orange-yellow (pH 1-2) to white (pH 4-6) to brown (pH 7-14) as the pH increases. Studies on the effect of pH on the color of potato protein powder show that at pH 7, the protein powder is whitish; when pH > 7, the color gradually turns light red as the pH increases; and when pH < 7, the color gradually turns pale yellow as the pH decreases.

[0028] Example 2 A continuous modification and purification process for preparing high-performance potato protein includes the following steps: S1. Impurity removal: Impurities are removed from the potato starch juice using a four-stage hydrocyclone to obtain potato protein juice.

[0029] S2. Protein extraction: Adjust the pH of the potato protein juice to 4.5, then heat the potato protein juice to 100°C using a steam heater and maintain the temperature for 10 min to denature the potato protein, break its spatial structure, and expose hydrophobic groups, thereby causing the protein to aggregate and precipitate. Collect the precipitate by centrifugation using a horizontal centrifuge to obtain low-purity potato wet protein.

[0030] S3. Protein Purification and Modification: Wet potato protein was transferred to a constant-temperature reaction vessel containing 0.3M NaOH at 60℃ for 3 hours to remove impurity groups. The mixture was then centrifuged at 4000 r / min for 10 min to obtain a potato protein alkaline solution. The pH of the potato protein alkaline solution was adjusted to 5 using HCl, with continuous stirring to ensure complete precipitation of the potato protein. The residue was collected, hydrolyzed with protease, and then spray-dried to obtain the protease hydrolysate. A complex enzyme with an activity of 100,000 U-200,000 U was used. The concentration of the residue (potato protein precipitate) was 3%. The pH was adjusted to 8 during hydrolysis, the reaction temperature was 55℃, and the reaction time was 4 hours. After resuspending in an equal volume of water, the mixture was transferred to an elution tank for homogenization at 4000 r / min. Centrifuge for 10 min at a 900 rpm for desalting, repeating this process twice until the supernatant conductivity reaches 500 μS / cm to obtain purified potato protein. The potato protein is then modified using an ultrasonic-assisted method, with the ultrasonic frequency set at 40 kHz, the ultrasonic time at 20 min, and the temperature controlled at 45 ℃.

[0031] S4. Protein Drying: The potato protein slurry purified and modified in step S3 is homogenized and crushed to 150 mesh using a homogenizer (speed 8000 r / min, homogenization time 30 min). The concentration of the potato protein slurry is controlled at 25%. The pH of the potato protein slurry is adjusted to 7 and spray dried. The spray drying parameters are set as follows: inlet air temperature 150℃, outlet air temperature 80℃, 15 MPa, drying time 20s, to obtain high-purity potato protein powder.

[0032] Evaluation of pH-Modified Purification The potato protein powder (pH-IMPP) prepared in this embodiment was compared with thermally flocculated protein (HF-PP), potato protein hydrolysate (PPH), and potato protein extracted by the EBA method (natural active potato protein, EBA-PP).

[0033] (I) Effect of pH-modified purification on the solubility of thermally flocculated proteins The appearance and solubility comparison chart of pH-IMPP, HF-PP, PPH, and EBA-PP prepared in this embodiment is shown in the figure. Figure 2As shown, EBA-PP exhibited the highest solubility (1.009 mg / mL), while HF-PP showed negligible solubility (0.003 mg / mL). This is attributed to protein denaturation caused by heat treatment, which reduces solubility. Notably, PPH and pH-IMPP showed significantly increased solubility (0.353 mg / mL and 0.360 mg / mL, respectively). Protein solubility increased significantly with increasing pH towards alkalinity due to extensive denaturation caused by electrostatic repulsion and deamidation. When the pH returned to neutral, the protein partially renatured but did not fully recover its native structure; therefore, its solubility was lower than under alkaline conditions but still much higher than that of HF-PP. Although thermal aggregation significantly reduces solubility and may impair functional properties, subsequent enzymatic or pH modification can improve the solubility of thermally flocculated proteins and restore some of their functional properties.

[0034] (II) Effect of pH-modified purification on the secondary structure of thermally flocculated proteins Table 1 shows the proportions of the secondary structures of pH-IMPP, HF-PP, PPH, and EBA-PP obtained in this embodiment.

[0035] Changes in chemical bonding and secondary structure in protein samples were detected by Fourier transform infrared spectroscopy (FTIR). Figure 3 This is a secondary structure analysis diagram of pH-IMPP, HF-PP, PPH, and EBA-PP prepared in this embodiment, where A is the Fourier transform infrared spectrum of the above samples; B, C, D, and E are Gaussian curve fitting diagrams of the amide I region of the proteins in the above samples. Figure 3 As shown, in the amide I region (1600-1700 cm⁻¹), all proteins exhibit a distinct peak at approximately 1652 cm⁻¹, a characteristic of secondary structure. The presence of typical protein characteristic peaks (amide I and amide II) indicates that the secondary structure of EBA-PP is well preserved and unchanged (e.g., Figure 3 As shown in Figure A). Curve fitting analysis of the amide I region showed that the proportions of α-helices (15.32%), β-sheets (25.87%), β-turns (23.62%), and random coils (18.51%) in EBA-PP were higher than those in HF-PP (α-helices: 14.68%; β-sheets: 22.31%; β-turns: 20.49%; random coils: 15.32%). Conversely, heating increased the content of aggregated chains from 16.67% to 27.20% (as shown in Figure A). Figure 3B. As shown in Table 1). These findings indicate the formation of protein aggregates and confirm the heat-induced transition of potato protein to a more rigid and aggregated conformation. Significant changes in the secondary structure of potato protein were observed after pH purification modification. pH modification significantly disrupted the hydrogen bond network, resulting in a significant decrease in β-sheet content from 22.31% to 18.37% (e.g., ...). Figure 3 (B. As shown in Table 1). Simultaneously, the relative proportion of random coil structures increased from 15.32% to 17.09%, indicating enhanced molecular disorder and partial unfolding. After pH purification modification, the α-helix content increased (from 14.68% to 16.58%), indicating enhanced structural compactness of HF-PP, while the aggregated β-chain content decreased (from 27.20% to 22.50%). These results indicate that pH purification modification can restore some of the secondary structure of thermoflocculated proteins, thereby increasing the solubility of potato protein.

[0036] (III) Effects of pH-modified purification on protein particle size distribution and zeta potential Particle size distribution and Zeta potential analysis were used to investigate aggregation phenomena in HF-PP, pH-IMPP, PPH and EBA-PP. Figure 4 This diagram shows the particle size distribution and analysis of pH-IMPP, HF-PP, PPH, and EBA-PP prepared in this embodiment. A represents the particle size distribution of HF-PP, B represents the particle size distribution of pH-IMPP, C represents the particle size distribution of PPH, D represents the particle size distribution of EBA-PP, E compares the average particle size of pH-IMPP with HF-PP, PPH, and EBA-PP, F compares the polydispersity index of pH-IMPP with HF-PP, PPH, and EBA-PP, and G shows the zeta potential analysis of pH-IMPP with HF-PP, PPH, and EBA-PP.

[0037] The average diameter of HF-PP is approximately 1062.8 nm, and it has a high polydispersity index (PDI) (0.489). Figure 4(As shown in E), indicating widespread thermally induced aggregation. Despite the relatively large average particle size of the EBA-PP system (approximately 1720 nm), the PDI remained low (0.332), suggesting that EBA-PP can form large, highly homogeneous aggregates or supramolecular assemblies under native conditions. In contrast, PPH exhibited a significantly smaller particle size, averaging 171.2 nm, and the lowest PDI (0.096), indicating the formation of small, highly dispersed peptide-protein fragments due to proteolytic cleavage. pH-IMPP showed a moderate particle size (approximately 399.48 nm) and a low polydispersity index (0.065), suggesting partial unfolding and deagglomeration during pH changes. Under neutral conditions far from the isoelectric point, the electrostatic repulsion between protein molecules was significantly enhanced, promoting protein structure unfolding and resulting in a smaller particle size. Compared to the control group, HP-PP modification significantly reduced the polydispersity index, indicating that enzymatic hydrolysis and pH changes promoted the formation of a more uniform particle distribution.

[0038] The zeta potential of proteins indicates the electrostatic stability of the suspension. EBA-PP showed a slightly stronger negative charge (-19.22 mV), sufficient to maintain moderate electrostatic repulsion, but insufficient to prevent the formation of large proto-aggregates. HF-PP exhibited the lowest surface charge (-14.28 mV), due to thermally induced denaturation, exposure of hydrophobic regions, and subsequent hydrophobic folding and disulfide bond exchange. HF-PP produced the largest and most heterogeneous aggregates, forming irregular micron-sized clusters. The decreased zeta potential (-14.28 mV) indicates weakened electrostatic repulsion, which favors flocculation, consistent with the widely reported thermal aggregation pathway of globular proteins. pH-IMPP enhanced the surface negative charge (-23.48 mV), indicating its relatively small and uniformly distributed particles, as electrostatic repulsion became more effective as the system moved away from the isoelectric point. pH changes away from the isoelectric point increased ionization of surface residues, increasing the zeta potential. PPH significantly enhanced the absolute value of the zeta potential (-25.25 mV).

[0039] (iv) Effect of pH-modified purification on AFM Figure 5 These are atomic force microscopy (AFM) images of the pH-IMPP, HF-PP, PPH, and EBA-PP samples prepared in this embodiment. The scanning range of the samples is 5 × 5 μm. AFM imaging revealed significant differences in the nanoscale structure of the four potato protein powders. Figure 5As shown, PPH and EBA-PP exhibit smooth, spherical particles with clear boundaries and minimal surface defects. These particles are uniformly distributed, indicating good dispersibility and no aggregation. In contrast, HF-PP and pH-IMPP show irregular, large aggregates with collapsed and wrinkled structures. Furthermore, HF-PP still has some undissolved particles on the surface of its irregular aggregates. HF-PP and pH-IMPP exhibit a broad and uneven height distribution, especially HF-PP, indicating a more disordered structure and a higher degree of protein-protein cross-linking. Mild protein extraction conditions preserved the native conformation of EBA-PP; PPH modification restored some of its native activity and reduced the degree of protein particle aggregation; thermal induction caused structural collapse in HF-PP; and pH-IMPP restored some of the native activity of HF-PP.

[0040] (v) Effects of pH-modified purification on foaming capacity and foam stability Figure 6 This is a comparison chart of the foaming properties of pH-IMPP, HF-PP, PPH, and EBA-PP prepared in this embodiment. In the chart, A is a photograph of the foaming of the above samples, B is the foaming capacity data of the above samples, and C is the foam stability data of the above samples. Figure 6 As shown, EBA-PP exhibited the strongest foaming ability, indicating its strong air-drawing capacity. HF-PP, however, showed a significant decrease in foaming ability to 42%, likely due to the formation of large aggregates that limited interfacial diffusion and adsorption. In contrast, HF-PP showed a slight increase in foam stability (92.33%), suggesting that the aggregated protein network facilitated the formation of a robust interfacial film. pH-IMPP partially recovered its foaming ability (80%), indicating improved dispersibility and interfacial activity through pH adjustment. However, its foam stability plummeted to 83%, possibly related to excessive electrostatic repulsion and weakened intermolecular interactions, leading to interfacial film instability. PPH showed only moderate foaming ability (44.3%), but relatively high foam stability (85%), suggesting that the residual aggregated structure still plays a significant role in foam stability.

[0041] (vi) Emulsification performance analysis Figure 7 This is a comparison chart of the emulsifying properties of pH-IMPP, HF-PP, PPH, and EBA-PP prepared in this embodiment. In the chart, A is a photograph of the emulsified samples, B is the emulsifying activity index of the samples, and C is the emulsifying stability index of the samples. Figure 7As shown, EBA-PP exhibited a relatively high emulsifying activity index (EAI, 26.37 m² / g) and a high emulsifying stability index (ESI, 52.81 min), indicating an optimal balance between interfacial adsorption and the formation of a stable interfacial film. In contrast, HF-PP significantly reduced emulsifying performance, with a marked decrease in both EAI (17.18 m² / g) and ESI (36.77 min). pH-IMPP significantly restored emulsifying activity, with EAI increasing to 25.56 m² / g, comparable to that of the native protein. However, the ESI remained low (15.81 min), suggesting that pH adjustment improved adsorption kinetics but failed to rebuild an interfacial film with cohesiveness and mechanical strength. Notably, PPH had a low EAI (27.24 m² / g) but a high ESI (28.68 min). This inverse relationship suggests that emulsifying activity and stability are controlled by different mechanisms.

[0042] In summary, the potato protein purified and modified using the method of this invention exhibits significantly improved functional properties and enhanced solubility, making it a high-performance potato protein suitable for food processing.

Claims

1. A continuous modification and purification process for preparing high-performance potato protein, characterized in that, Includes the following steps: S1. Impurity removal: The potato starch is processed to separate the juice and impurities, resulting in potato protein juice; S2. Protein extraction: Heat potato protein juice to 100-110℃, maintain the temperature to coagulate, collect the precipitate, and obtain wet potato protein. S3. Protein Purification and Modification: Wet potato protein was transferred to a constant-temperature reaction vessel containing an alkaline solution at 50-60℃ to remove impurity groups, yielding an alkaline potato protein solution. The pH of the alkaline potato protein solution was adjusted to 4-6 to allow for complete precipitation of the potato protein. The residue was collected, hydrolyzed with protease, and then spray-dried to obtain protease hydrolysate. The hydrolysate was resuspended in water and homogenized in an elution tank at a water-to-hydrolysate volume ratio of 2-4:0.

5. Centrifugation was performed, and this process was repeated 2-3 times until the conductivity of the supernatant reached 50-500 μS / cm, yielding purified potato protein. The potato protein was then modified using an ultrasonic-assisted method. S4. Protein drying: After homogenizing the potato protein purified and modified in step S3, spray dry to obtain potato protein powder.

2. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S2, the pH of the potato protein juice is adjusted to 4.5-5.5 before heating.

3. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S3, the mass ratio of the protein hydrolysate to the liquid is 2-4:0.5 when the protein hydrolysate is resuspended in water.

4. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S3, the mass ratio of potato wet protein to alkaline solution is 1-1.5:0.5, the alkaline solution is NaOH or KOH, and the pH of the alkaline solution is 10-11.

5. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S3, the pH of the potato protein alkaline solution is adjusted to 5.

5.

6. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S3, the ultrasonic frequency is set to 40 kHz, the ultrasonic time is 20 min, and the temperature is controlled at 45-55℃.

7. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S3, a complex enzyme with an activity of 100,000 U-200,000 U is used for the protease, the mass concentration of the collected residue is 3%-5%, the pH value is adjusted to 8 during hydrolysis, the reaction temperature is 55℃, and the reaction time is 4h.

8. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S4, the pH of the potato protein slurry is adjusted to 7 before spraying.

9. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S4, the concentration of potato protein slurry is controlled at 15% to 25%; the spray drying parameters are set as follows: inlet air temperature 150-180℃, outlet air temperature 80-85℃, 15-20 MPa, and drying time 20s.

10. The continuous modification and purification process for preparing high-performance potato protein according to claim 1, characterized in that: In step S4, the potato protein particles are broken down to 30-150 mesh using a homogenizer.

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