Corn starch-whey protein isolate amyloid fiber compound with high digestion resistance as well as preparation method and application of corn starch-whey protein isolate amyloid fiber compound
By pretreating whey protein isolate solution with cysteine and pulsed electric field, combined with acid heat treatment and cogelatinization technology, a corn starch-whey protein isolate amyloid fiber complex was prepared, which solved the problem of postprandial hyperglycemia caused by rapid digestion of corn starch and achieved the preparation of high resistant starch and health protection effect.
Patent Information
- Application Number
- CN202511309023.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-12
- Publication Date
- 2025-12-09
AI Technical Summary
Corn starch is rapidly digested in the human body, leading to elevated postprandial blood sugar and increasing the risk of chronic diseases. Existing technologies are insufficient to effectively reduce starch digestibility.
A corn starch-whey protein isolate amyloid fiber complex was prepared by pretreating whey protein isolate solution with cysteine and pulsed electric field, followed by acid heat treatment and cogelatinization, and then adding quercetin for covalent cross-linking.
It increases the resistant starch content and reduces starch digestibility, and has the advantages of being environmentally friendly and easy to operate, making it suitable for large-scale production and applicable to foods for diabetic patients.
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Figure CN121086352A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of starch processing technology, specifically to a corn starch-whey protein isolate amyloid fiber complex with high digestibility, its preparation method, and its application. Background Technology
[0002] Corn starch is widely used in the food industry due to its advantages such as good biocompatibility, wide availability, renewable nature, low cost, and high yield. However, after corn starch is ingested, it is hydrolyzed into glucose by amylases in the human intestine, leading to elevated postprandial blood glucose levels and increasing the risk of chronic diseases such as type 2 diabetes, cardiovascular disease, and obesity. Based on in vitro hydrolysis time, starch is classified into rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). Ingestion of RDS causes a rapid rise in postprandial blood glucose. Previous studies have shown that intake of RS does not cause a rapid rise in postprandial blood glucose; therefore, increasing the RS content and decreasing the RDS content in starch can help maintain blood glucose levels and may be a key solution to diet-related chronic disease problems. Recent studies have shown that starch-protein interactions reduce starch digestibility, thereby preventing postprandial diabetic complications. Proteins interfere with nutritional properties and promote starch malabsorption by inhibiting enzyme binding sites and altering starch digestibility.
[0003] Whey protein isolate is a high-quality protein with a balanced amino acid composition, attracting increasing attention in the food and medical industries. Protein fibrillation is considered a promising method for altering the molecular structure of food proteins and has received widespread attention from researchers in recent years. Amyloid fibrils, with their high aspect ratio and high stiffness, facilitate the formation of entangled gel networks. Studies have shown that amyloid fibrils inhibit starch digestibility.
[0004] However, proteins typically have a more compact structure and lower solubility, which may limit their acidic hydrolysis in the early stages of fibrillation and lead to reduced fibrillation efficiency and conversion rate. Summary of the Invention
[0005] The main objective of this invention is to provide a corn starch-whey protein isolate amyloid fiber complex, its preparation method, and its application, in order to overcome the shortcomings of the prior art.
[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:
[0007] One aspect of the present invention provides a method for preparing a corn starch-whey protein isolate amyloid fiber complex, comprising:
[0008] Cysteine was mixed with whey protein isolate solution and pretreated with a pulsed electric field to obtain the treated whey protein isolate solution.
[0009] The treated whey protein isolate solution was subjected to high-speed shear-assisted acid-heat treatment to fibrose the whey protein isolate, resulting in whey protein isolate amyloid fibers.
[0010] Furthermore, the whey protein isolate amyloid fibers and corn starch suspension are co-gelatinized, and then quercetin is added to covalently crosslink the whey protein isolate amyloid fibers to obtain a corn starch-whey protein isolate amyloid fiber complex.
[0011] Another aspect of the present invention provides a corn starch-whey protein isolate amyloid fiber complex prepared by the aforementioned preparation method.
[0012] Another aspect of the present invention provides the application of the aforementioned corn starch-whey protein isolate amyloid fiber complex in the preparation of foods for diabetic patients.
[0013] Compared with the prior art, the present invention has at least the following advantages:
[0014] 1) The preparation method provided by the present invention utilizes cysteine to treat whey protein isolate and further performs pulsed electric field pretreatment. Cysteine and pulsed electric field pretreatment synergistically promote the structural unfolding and subsequent fibrillation of whey protein isolate, thereby obtaining whey protein isolate amyloid fibers with rich content.
[0015] 2) The preparation method provided by the present invention covalently crosslinks quercetin and whey protein isolate amyloid fibers using a free radical method. Quercetin can act as a crosslinking agent between whey protein isolate amyloid fibers, forming a thicker amyloid fiber layer on the starch surface, which is beneficial to reducing starch digestibility. In addition, quercetin itself can also inhibit amylase activity, and can synergistically reduce starch digestibility with amyloid fibers.
[0016] 3) The corn starch-whey protein isolate amyloid fiber complex provided by this invention has a high RS content, which is of great practical significance for protecting human health and preventing diabetes and related metabolic problems. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1This is a schematic diagram illustrating the preparation process of a highly resistant corn starch-whey protein isolate amyloid fiber complex in a typical embodiment of the present invention.
[0019] Figure 2 This is a comparison graph of the intrinsic fluorescence intensity of the samples prepared in Comparative Examples 1-3;
[0020] Figure 3 This is a comparison graph of the ThT fluorescence intensity of the samples prepared in Comparative Examples 4-6;
[0021] Figure 4 This is a graph showing the effect of quercetin dosage on the inhibition rate of α-amylase. Detailed Implementation
[0022] In view of the problems existing in the prior art, the inventors of this case have conducted extensive and in-depth research and have provided a corn starch-whey protein isolate amyloid fiber complex and its preparation method.
[0023] The inventors in this case discovered that the structure of natural proteins can be altered through chemical modification, biological methods, and physical treatment. Cysteine, a naturally occurring amino acid, provides an environmentally friendly and non-toxic method for modifying protein structure. Cysteine can promote protein molecule unfolding and enhance its functional properties.
[0024] Furthermore, the inventors of this case have discovered that pulsed electric fields, as a novel non-thermal physical processing technology, have emerged in food processing, enabling the induction of structural changes in biomolecules using electric fields. Amyloid fibrils produced from proteins pretreated with cysteine and pulsed electric fields may exhibit better functional properties than those produced from naturally occurring proteins.
[0025] Based on this, the inventors of this case designed a corn starch-whey protein isolate amyloid fiber complex that can be used to reduce starch digestibility in diabetic patients.
[0026] The following will further explain the technical solution, its implementation process, and its principles. However, it should be understood that the specific embodiments disclosed below are merely exemplary of the present invention, and the present invention can be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as representative bases for different ways in which those skilled in the art to which the claims pertain may employ the invention in any suitable detailed embodiment.
[0027] As one aspect of the technical solution of this invention, a method for preparing a corn starch-whey protein isolate amyloid fiber complex includes:
[0028] Cysteine was mixed with whey protein isolate solution and pretreated with a pulsed electric field to obtain the treated whey protein isolate solution.
[0029] The treated whey protein isolate solution was subjected to high-speed shear-assisted acid-heat treatment to fibrose the whey protein isolate, resulting in whey protein isolate amyloid fibers.
[0030] Furthermore, the whey protein isolate amyloid fibers and corn starch suspension are co-gelatinized, and then quercetin is added to covalently crosslink the whey protein isolate amyloid fibers to obtain a corn starch-whey protein isolate amyloid fiber complex.
[0031] In some embodiments, the whey protein isolate solution is obtained by mixing whey protein isolate powder with phosphate buffer.
[0032] In some embodiments, the concentration of the whey protein isolate solution is 1-10 w / v.
[0033] In some embodiments, the mass ratio of cysteine to whey protein isolate in the whey protein isolate solution is 1:5 to 1:50.
[0034] In some implementations, the pulsed electric field pretreatment uses a pulsed electric field strength of 5-60 kV / cm and a pulsed electric field pretreatment time of 5-60 min.
[0035] In some embodiments, the preparation method specifically includes: adjusting the pH of the treated whey protein isolate solution to 2.0-5.0 with acid, then heating at 70-90°C for 2-24 hours to perform the acid heat treatment, and performing high shear treatment for 2-5 minutes at specific time intervals during the heating process, followed by continuing the reaction at 70-90°C to finally obtain whey protein isolate amyloid fibers, wherein the specific time is 5-30 minutes.
[0036] In some preferred embodiments, the acid includes, but is not limited to, one or more combinations of hydrochloric acid, phosphoric acid, acetic acid, and citric acid.
[0037] In some embodiments, the preparation method specifically includes: adding corn starch and whey protein isolate amyloid fibers to deionized water and stirring for 1-4 hours, then performing co-gelatinization treatment, cooling to room temperature after the treatment, adding hydrogen peroxide and ascorbic acid and reacting for 1-4 hours; then adding quercetin to continue the reaction to obtain a corn starch-whey protein isolate amyloid fiber complex.
[0038] In some embodiments, the corn starch suspension is obtained by mixing corn starch with water.
[0039] Furthermore, the preparation method specifically includes: mixing corn starch with water to form a corn starch suspension, and then mixing it with whey protein isolate amyloid fibers for co-gelatinization treatment.
[0040] In some embodiments, the concentration of the corn starch suspension is 3-10 w / v.
[0041] In some embodiments, the mass ratio of the whey protein isolate amyloid fibers to the corn starch in the corn starch suspension is 1:2 to 1:20.
[0042] In some embodiments, the cogelatinization treatment is performed at a temperature of 70-90°C for a time of 30-60 minutes.
[0043] In some embodiments, the mass ratio of quercetin to whey protein isolate amyloid cellulose is 1:2 to 1:30.
[0044] In some embodiments, the hydrogen peroxide is derived from an aqueous solution of hydrogen peroxide, the concentration of which is 1-10 mol / L.
[0045] In some embodiments, the ascorbic acid is derived from an aqueous solution of ascorbic acid, the concentration of which is 0.1-2 w / v.
[0046] In some implementation schemes, the reaction continues for 5-48 hours after the addition of quercetin.
[0047] For some more specific implementation plans, please refer to Figure 1 As shown, a method for preparing a corn starch-whey protein isolate amyloid fiber complex includes the following steps:
[0048] Step 1): Dissolve whey protein isolate powder in phosphate buffer solution with a pH of 8.5 and stir until homogeneous to obtain whey protein isolate solution. Add cysteine to the whey protein isolate solution and mix. Then, pretreat the above solution with a pulsed electric field to obtain whey protein isolate solution with cysteine and pulsed electric field pretreatment.
[0049] Step 2): Adjust the pH of the whey protein isolate solution obtained in Step 1) to 2.0-5.0 with hydrochloric acid, then heat at 70-90℃ for 2-24 hours with magnetic stirring. During the heating process, perform high shear treatment for 2-5 minutes at specific time intervals, and then continue the reaction at 70-90℃ to obtain whey protein isolate amyloid cellulose solution, which is then freeze-dried to obtain powder.
[0050] Step 3): Corn starch was dissolved in deionized water to prepare a corn starch suspension. The whey protein isolate amyloid fibers obtained in Step 2) and corn starch were added to deionized water and stirred for 1-4 hours before co-gelatinization. After co-gelatinization, the solution was cooled to room temperature, and hydrogen peroxide and ascorbic acid were added as a redox initiator system. Subsequently, quercetin was added to the above reaction solution to continue the reaction, yielding a corn starch-whey protein isolate amyloid fiber complex.
[0051] As another aspect of the technical solution of the present invention, it relates to a corn starch-whey protein isolate amyloid fiber complex prepared by the aforementioned preparation method.
[0052] In some preferred embodiments, the resistant starch content in the corn starch-whey protein isolate amyloid fiber complex is 42.78% to 48.97%.
[0053] As another aspect of the technical solution of the present invention, it also relates to the application of the aforementioned corn starch-whey protein isolate amyloid fiber complex in the preparation of various foods for diabetic patients.
[0054] In summary, this invention involves adding cysteine to a whey protein isolate solution and pretreating it with a pulsed electric field. Subsequently, acid-heat treatment induces the cysteine and the pretreated whey protein isolate to undergo fibrillation, forming amyloid fibers. These fibers are then co-gelatinized with a corn starch solution, followed by the addition of quercetin to obtain a corn starch-whey protein isolate amyloid fiber complex. Specifically, the synergistic effect of cysteine and pulsed electric field treatment promotes the unfolding of the whey protein isolate. Quercetin reacts with the nucleophilic groups of several amino acids, such as tryptophan and cysteine, in the amyloid fibers, thereby inducing covalent cross-linking between quercetin and the whey protein isolate amyloid fibers through these reactive groups.
[0055] The corn starch-whey protein isolate amyloid fiber complex prepared by this invention has a high resistant starch content, which solves the disadvantage of high glycemic index of corn starch. Moreover, the pulsed electric field and cogelatinization treatment in the preparation process have the advantages of being environmentally friendly, simple to operate, and flexible to adjust, making it suitable for large-scale production and market promotion.
[0056] The present invention is further illustrated below by way of examples, but the invention is not limited to the scope of the examples described. All reagents and raw materials used in the following examples are commercially available, and test methods not specifically specified are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.
[0057] Example 1
[0058] A method for preparing a highly resistant corn starch-whey protein isolate amyloid fiber complex includes the following steps:
[0059] (1) Preparation of whey protein isolate amyloid fibers pretreated with cysteine and pulsed electric field
[0060] 2g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 5% (w / v) protein solution. 0.05g of cysteine was added to the whey protein isolate solution and mixed for 0.5h. The solution was then treated with a pulsed electric field of 5kV / cm for 15min. Subsequently, the pH of the whey protein isolate solution treated with the pulsed electric field was adjusted to 2.0 with 6M HCl solution. The solution was heated in a water bath at 90℃ for 4h. During the heating process, high shear treatment was performed for 2min every 10min. The reaction was then continued at 90℃. After heating was completed, the solution was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0061] (2) Preparation of corn starch-whey protein isolate amyloid fiber complex
[0062] 3g of corn starch and 0.5g of whey protein isolate amyloid fibers were dissolved in 100mL of deionized water and stirred for 1 hour. The mixture was then heated at 90℃ for 30 minutes with stirring, and cooled to room temperature after heating. Hydrogen peroxide aqueous solution (2mol / L) and ascorbic acid aqueous solution (1w / v%) were added to the above solution and reacted for 1 hour. Subsequently, 0.05g of quercetin was added and reacted for 5 hours to obtain a highly resistant corn starch-whey protein isolate amyloid fiber complex.
[0063] Example 2
[0064] A method for preparing a highly resistant corn starch-whey protein isolate amyloid fiber complex includes the following steps:
[0065] (1) Preparation of whey protein isolate amyloid fibers pretreated with cysteine and pulsed electric field
[0066] 2g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. 0.4g of cysteine was added to the whey protein isolate solution and mixed for 2h. The solution was then treated with a pulsed electric field of 30kV / cm for 30min. Subsequently, the pH of the whey protein isolate solution treated with the pulsed electric field was adjusted to 2.0 with 6M HCl solution. The solution was heated in a water bath at 90℃ for 12h. During the heating process, high shear treatment was performed for 3min every 5min. The reaction was then continued at 90℃. After heating was completed, the solution was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0067] (2) Preparation of corn starch-whey protein isolate amyloid fiber complex
[0068] 10 g of corn starch and 5 g of whey protein isolate amyloid fibers were dissolved in 100 mL of deionized water and stirred for 2 h. The mixture was then heated at 90 °C for 30 min with stirring, and cooled to room temperature after heating. Hydrogen peroxide aqueous solution (1 mol / L) and ascorbic acid aqueous solution (0.1 w / v%) were added to the above solution and reacted for 2 h. Subsequently, 2.5 g of quercetin was added and reacted for 24 h to obtain a highly resistant corn starch-whey protein isolate amyloid fiber complex.
[0069] Example 3
[0070] A method for preparing a highly resistant corn starch-whey protein isolate amyloid fiber complex includes the following steps:
[0071] (1) Preparation of whey protein isolate amyloid fibers pretreated with cysteine and pulsed electric field
[0072] 2g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. 0.2g of cysteine was added to the whey protein isolate solution and mixed for 1 hour. The solution was then treated with a pulsed electric field of 60kV / cm for 20 minutes. Subsequently, the pH of the whey protein isolate solution treated with the pulsed electric field was adjusted to 3.0 with 6M HCl solution. The solution was heated in a water bath at 90°C for 8 hours. During the heating process, high shear treatment was performed for 5 minutes every 30 minutes. The reaction was then continued at 90°C. After heating was completed, the solution was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0073] (2) Preparation of corn starch-whey protein isolate amyloid fiber complex
[0074] 3g of corn starch and 1g of whey protein isolate amyloid fibers were dissolved in 100mL of deionized water and stirred for 3 hours. The mixture was then heated at 90℃ for 30 minutes with stirring, and cooled to room temperature after heating. Hydrogen peroxide aqueous solution (5mol / L) and ascorbic acid aqueous solution (0.5w / v%) were added to the above solution and reacted for 1 hour. Subsequently, 0.1g of quercetin was added and the reaction was carried out for 10 hours to obtain a highly resistant corn starch-whey protein isolate amyloid fiber complex.
[0075] Example 4
[0076] A method for preparing a highly resistant corn starch-whey protein isolate amyloid fiber complex includes the following steps:
[0077] (1) Preparation of whey protein isolate amyloid fibers pretreated with cysteine and pulsed electric field
[0078] 1 g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 1% (w / v) protein solution. 0.02 g of cysteine was added to the whey protein isolate solution and mixed for 6 h. The solution was then treated with a pulsed electric field of 5 kV / cm for 60 min. Subsequently, the pH of the whey protein isolate solution treated with the pulsed electric field was adjusted to 5.0 with 6 M HCl solution. The solution was heated in a water bath at 70 °C for 24 h. During the heating process, high shear treatment was performed for 4 min every 20 min. The reaction was then continued at 70 °C. After heating was completed, the solution was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0079] (2) Preparation of corn starch-whey protein isolate amyloid fiber complex
[0080] 10 g of corn starch and 0.5 g of whey protein isolate amyloid fibers were dissolved in 100 mL of deionized water and stirred for 4 h. The mixture was then heated at 70 °C for 60 min with stirring, and cooled to room temperature after heating. Hydrogen peroxide aqueous solution (10 mol / L) and ascorbic acid aqueous solution (2 w / v%) were added to the above solution and reacted for 1 h. Subsequently, 0.02 g of quercetin was added and reacted for 5 h to obtain a highly resistant corn starch-whey protein isolate amyloid fiber complex.
[0081] Example 5
[0082] A method for preparing a highly resistant corn starch-whey protein isolate amyloid fiber complex includes the following steps:
[0083] (1) Preparation of whey protein isolate amyloid fibers pretreated with cysteine and pulsed electric field
[0084] 3g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare an 8% (w / v) protein solution. 0.6g of cysteine was added to the whey protein isolate solution and mixed for 1 hour. The solution was then treated with a pulsed electric field of 20kV / cm for 10 minutes. Subsequently, the pH of the whey protein isolate solution treated with the pulsed electric field was adjusted to 2.0 with 6M HCl solution. The solution was heated at 80°C for 2 hours in a water bath. During the heating process, high shear treatment was performed for 3 minutes every 15 minutes. The reaction was then continued at 80°C. After heating was completed, the solution was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0085] (2) Preparation of corn starch-whey protein isolate amyloid fiber complex
[0086] 5 g of corn starch and 1 g of whey protein isolate amyloid fiber were dissolved in 100 mL of deionized water and stirred for 3 h. The mixture was then heated at 80 °C for 40 min with stirring, and cooled to room temperature after heating. Hydrogen peroxide aqueous solution (10 mol / L) and ascorbic acid aqueous solution (2 w / v%) were added to the above solution and reacted for 4 h. Subsequently, 0.04 g of quercetin was added and reacted for 48 h to obtain a highly resistant corn starch-whey protein isolate amyloid fiber complex.
[0087] Comparative Example 1
[0088] Preparation of whey protein isolates pretreated with pulsed electric field:
[0089] 2g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. This solution was then treated with a pulsed electric field of 20 kV / cm for 6 hours to obtain pulsed electric field pretreated whey protein isolate.
[0090] Comparative Example 2
[0091] Preparation of cysteine-treated whey protein isolate:
[0092] 2g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. 0.4g of cysteine was added to the whey protein isolate solution and mixed for 2 hours to obtain cysteine-treated whey protein isolate.
[0093] Comparative Example 3
[0094] Preparation of whey protein isolate pretreated with cysteine and pulsed electric field:
[0095] 2 g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. 0.4 g of cysteine was added to the whey protein isolate solution and mixed for 2 h. The solution was then treated with a pulsed electric field of 20 kV / cm for 6 h to obtain cysteine-pretreated and pulsed electric field-treated whey protein isolate.
[0096] Comparative Example 4
[0097] Preparation of whey protein isolate amyloid fibers pretreated with pulsed electric field:
[0098] 2 g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. This solution was treated with a pulsed electric field of 20 kV / cm for 6 h. Subsequently, the pH of the whey protein isolate solution treated with the pulsed electric field was adjusted to 2.0 with 6 M HCl solution, and then heated in a water bath at 90 °C for 12 h. After heating, it was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0099] Comparative Example 5
[0100] Preparation of cysteine-treated whey protein isolate amyloid fibers:
[0101] 2 g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. 0.4 g of cysteine was added to the whey protein isolate solution and mixed for 2 h. Subsequently, the pH of the whey protein isolate solution treated with a pulsed electric field was adjusted to 2.0 with 6 M HCl solution, and heated in a water bath at 90 °C for 12 h. After heating, it was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0102] Comparative Example 6
[0103] Preparation of whey protein isolate amyloid fibrils pretreated with cysteine and pulsed electric field:
[0104] 2 g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. 0.4 g of cysteine was added to the whey protein isolate solution and mixed for 2 h, followed by treatment with a pulsed electric field of 20 kV / cm for 6 h. Subsequently, the pH of the pulsed electric field-treated whey protein isolate solution was adjusted to 2.0 with 6 M HCl solution, and the solution was heated in a water bath at 90 °C for 12 h. After heating, the solution was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0105] Comparative Example 7
[0106] Preparation of corn starch-whey protein isolate amyloid fiber complex:
[0107] 2g of whey protein isolate was dissolved in phosphate buffer with a pH of 8.5 to prepare a 2% (w / v) protein solution. Then, the pH of the whey protein isolate solution was adjusted to 2.0 with 6M HCl solution and heated in a water bath at 90°C for 4 hours. After heating, it was immediately placed in ice water to cool and obtain whey protein isolate amyloid filaments.
[0108] 3g of corn starch and 0.5g of whey protein isolate amyloid cellulose were dissolved in 100mL of deionized water and stirred until homogeneous. The mixture was heated at 90℃ for 30min with stirring, and then cooled to room temperature after heating. Hydrogen peroxide and ascorbic acid were added to the above solution and reacted for 1h. Subsequently, 0.01g of quercetin was added and reacted for 4h to obtain the corn starch-whey protein isolate amyloid cellulose complex.
[0109] Comparative Example 8
[0110] Preparation of corn starch-pulsed electric field pretreated whey protein isolate amyloid fiber complex:
[0111] 2g of whey protein isolate was dissolved in phosphate buffer with a pH of 8.5 to prepare a 2% (w / v) protein solution. The solution was treated with a pulsed electric field strength of 20kV / cm for 3h. Subsequently, the pH of the whey protein isolate solution treated with the pulsed electric field was adjusted to 2.0 with 6M HCl solution. The solution was heated in a water bath at 90℃ for 4h. After heating, it was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0112] 3g of corn starch and 0.5g of whey protein isolate amyloid cellulose were dissolved in 100mL of deionized water and stirred until homogeneous. The mixture was heated at 90℃ for 30min with stirring, and then cooled to room temperature after heating. Hydrogen peroxide and ascorbic acid were added to the above solution and reacted for 1h. Subsequently, 0.01g of quercetin was added and reacted for 4h to obtain the corn starch-whey protein isolate amyloid cellulose complex.
[0113] Comparative Example 9
[0114] Preparation of corn starch-cysteine pretreated whey protein isolate amyloid fiber complex:
[0115] 2g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. 0.05g of cysteine was added to the whey protein isolate solution and mixed for 0.5h. Subsequently, the pH of the cysteine-treated whey protein isolate solution was adjusted to 2.0 with 6M HCl solution. The solution was heated at 90°C in a water bath for 4h. After heating, it was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0116] 3g of corn starch and 0.5g of whey protein isolate amyloid cellulose were dissolved in 100mL of deionized water and stirred until homogeneous. The solution was heated at 90℃ for 30min with stirring, and then cooled to room temperature after heating. Hydrogen peroxide and ascorbic acid were added to the solution and reacted for 1h, followed by the addition of 0.01g of quercetin and reaction for 4h to obtain the corn starch-whey protein isolate amyloid cellulose complex.
[0117] Comparative Example 10
[0118] Preparation of corn starch-pulsed electric field and cysteine pretreated whey protein isolate amyloid fiber complex (without quercetin):
[0119] 2g of whey protein isolate was dissolved in phosphate buffer at pH 8.5 to prepare a 2% (w / v) protein solution. 0.05g of cysteine was added to the whey protein isolate solution and mixed for 0.5h. The solution was then treated with a pulsed electric field of 20kV / cm for 3h. Subsequently, the pH of the whey protein isolate solution treated with the pulsed electric field was adjusted to 2.0 with 6M HCl solution. The solution was heated in a water bath at 90℃ for 4h. After heating, it was immediately cooled in ice water to obtain whey protein isolate amyloid filaments.
[0120] Dissolve 3g of corn starch and 0.5g of whey protein isolate amyloid fibers in 100mL of deionized water and stir until homogeneous. Heat at 90℃ for 30min while stirring. After heating, cool to room temperature to obtain corn starch-whey protein isolate amyloid fiber complex.
[0121] Please see Figure 2 As shown, the intrinsic fluorescence intensity of the samples prepared in Comparative Examples 1-3 is compared. After synergistic treatment with cysteine and pulsed electric field, the maximum fluorescence emission peak shows a significant red shift and the fluorescence intensity decreases significantly, indicating that cysteine and pulsed electric field treatment unfolds the whey protein isolate structure.
[0122] Please see Figure 3 The figure shows a comparison of ThT fluorescence intensity of the samples prepared in Comparative Examples 4-6. ThT fluorescence spectroscopy is a sensitive and accurate method for monitoring the formation of amyloid fibrils. β-sheet structure is positively correlated with amyloid fibril content. The increased fluorescence intensity of whey isolate amyloid fibrils after synergistic treatment with cysteine and pulsed electric field indicates an increase in the content of β-sheets formed after synergistic treatment with cysteine and pulsed electric field, thus increasing the fibril content.
[0123] Please see Figure 4 The figure shown is a graph illustrating the effect of quercetin dosage on the inhibition rate of α-amylase, demonstrating that quercetin itself has a certain inhibitory effect on amylase activity.
[0124] Please refer to Table 1. The absorbance ratio of 1047 to 1022 (R1047 / 1022) can be used to characterize the short-range ordered structure of starch. The R values of the starch complexes prepared in Examples 1-3 and Comparative Examples 7-9 are shown in Table 1. 1047 / 1022 The values and relative RC values are shown in Table 1:
[0125] Table 1: R values for different samples 1047 / 1022Value and relative RC value
[0126]
[0127] As shown in Table 1, compared with Comparative Examples 7-10, the starch complexes prepared in Examples 1-3 exhibited higher short-range order. Higher short-range order is more beneficial for reducing starch digestibility. Relative crystallinity (RC) can be used to characterize the long-range ordered structure of starch. Compared with Comparative Examples 7-9, the complexes prepared in Examples 1-3 exhibited higher long-range order, and higher long-range order is more beneficial for reducing starch digestibility.
[0128] Please refer to Table 2. The resistant starch RS content, SDS content, and RDS content data of the starch complexes obtained in Examples 1-3 and Comparative Examples 7-9 are shown in Table 2:
[0129] Table 2: Starch composition of different samples
[0130]
[0131] As shown in Table 2, compared with Comparative Examples 7-10, the starch complexes prepared in Examples 1-3 have higher resistant starch (RS) and SDS content and lower RDS content.
[0132] In addition, the inventors of this case also conducted experiments with the other conditions listed in this specification, referring to the aforementioned embodiments, and similarly obtained corn starch-whey protein isolate fiber complex that can reduce starch digestibility, and obtained relatively ideal results in all cases.
[0133] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for preparing a corn starch-whey protein isolate amyloid fiber complex, characterized in that, include: Cysteine was mixed with whey protein isolate solution and pretreated with a pulsed electric field to obtain the treated whey protein isolate solution. The treated whey protein isolate solution was subjected to high-speed shear-assisted acid-heat treatment to fibrose the whey protein isolate, resulting in whey protein isolate amyloid fibers. Furthermore, the whey protein isolate amyloid fibers and corn starch suspension are co-gelatinized, and then quercetin is added to covalently crosslink the whey protein isolate amyloid fibers to obtain a corn starch-whey protein isolate amyloid fiber complex.
2. The preparation method according to claim 1, characterized in that: The whey protein isolate solution is obtained by mixing whey protein isolate powder with phosphate buffer. And / or, the concentration of the whey protein isolate solution is 1-10 w / v%. And / or, the mass ratio of cysteine to whey protein isolate in the whey protein isolate solution is 1:5 to 1:50; And / or, the pulse electric field pretreatment uses a pulse electric field strength of 5-60 kV / cm and a pulse electric field pretreatment time of 5-60 min.
3. The preparation method according to claim 1, characterized in that, Specifically, it includes: The pH of the treated whey protein isolate solution was adjusted to 2.0-5.0 with acid, and then heated at 70-90°C for 2-24 hours. During the heating process, high shear treatment was performed for 2-5 minutes at specific time intervals, and then the reaction was continued at 70-90°C to finally obtain whey protein isolate amyloid fibers, wherein the specific time was 5-30 minutes. Preferably, the acid includes one or more combinations of hydrochloric acid, phosphoric acid, acetic acid, and citric acid.
4. The preparation method according to claim 1, characterized in that, Specifically, it includes: Corn starch and whey protein isolate amyloid fibers were added to deionized water and stirred for 1-4 hours for co-gelatinization. After the process was completed, the mixture was cooled to room temperature, and hydrogen peroxide and ascorbic acid were added for 1-4 hours. Quercetin was then added to continue the reaction, resulting in a corn starch-whey protein isolate amyloid fiber complex.
5. The preparation method according to claim 4, characterized in that, include: Corn starch is mixed with water to form a corn starch suspension, and then mixed with whey protein isolate amyloid fibers for co-gelatinization. Preferably, the concentration of the corn starch suspension is 3-10 w / v%.
6. The preparation method according to claim 4, characterized in that: The mass ratio of whey protein isolate amyloid fiber to corn starch is 1:2 to 1:
20.
7. The preparation method according to claim 4, characterized in that: The cogelatinization process is carried out at a temperature of 70-90℃ for 30-60 minutes.
8. The preparation method according to claim 4, characterized in that: The mass ratio of quercetin to whey protein isolate amyloid fibers is 1:2 to 1:30; And / or, the hydrogen peroxide is derived from an aqueous solution of hydrogen peroxide, the concentration of which is 1-10 mol / L; and / or, the ascorbic acid is derived from an aqueous solution of ascorbic acid, the concentration of which is 0.1-2 w / v%. And / or, the reaction continues for 5-48 hours after the addition of quercetin.
9. A corn starch-whey protein isolate amyloid fiber complex prepared by any one of the preparation methods described in claims 1-8; Preferably, the resistant starch content in the corn starch-whey protein isolate amyloid fiber complex is 42.78-48.97%.
10. The use of the corn starch-whey protein isolate amyloid fiber complex according to claim 9 in the preparation of food for diabetic patients.