A polyphenol-nanoselenium modified starch compound and a preparation method and application thereof

Abstract

The application belongs to the technical field of modified starch, and particularly relates to a polyphenol-nano selenium modified starch compound and a preparation method and application thereof. The preparation method of the polyphenol-nano selenium modified starch compound comprises the following steps: step one, preparing resveratrol-nano selenium particles RSV-SeNPs and pterostilbene-nano selenium particles PTS-SeNPs respectively; and step two, mixing the RSV-SeNPs and the PTS-SeNPs with starch respectively, and carrying out pasting, drying and crushing to obtain RSV-SeNPs modified starch compound and PTS-SeNPs modified starch compound respectively. The polyphenol-nano selenium particles are used as a core modifier, the hydrogen bond interaction between the surface hydroxyl characteristics and starch molecules is utilized, the starch is mildly modified, and differentiated digestion characteristics (regulation trend of fast and slow digestion) are obtained. The mild composite method is adopted, harsh conditions such as high temperature, strong acid and strong base are not needed, the starch molecule skeleton is not damaged, the safety is high, and the method is suitable for food and health product systems.

Description

Technical Field

[0001] This invention belongs to the field of modified starch technology, and particularly relates to a polyphenol-nano selenium modified starch composite, its preparation method and application. Background Technology

[0002] Starch is a major source of dietary energy for the human body, and its digestion rate directly determines postprandial blood glucose levels and energy supply efficiency, which is closely related to metabolic health. Based on digestive kinetics, starch can be classified into rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). By regulating the proportions of starch digestible components, different functional needs such as blood sugar control, satiety, or rapid energy supply can be met. Therefore, the targeted regulation of starch digestibility is an important research direction in the field of food science.

[0003] Existing starch modification technologies mainly include physical modification, chemical modification, and enzymatic modification. Physical modification (such as moist heat and extrusion) requires harsh conditions, which can easily damage the natural structure of starch and limit the precision of regulation. Chemical modification (such as cross-linking and esterification) requires the introduction of chemical reagents, which poses a risk of byproduct residues and limits the safety of application. Enzymatic modification is costly and has a limited effect on regulating digestibility, making it difficult to achieve differentiated and precise regulation.

[0004] In recent years, the non-covalent interaction between natural active ingredients and starch for mild modification has become a research hotspot. Polyphenols, rich in phenolic hydroxyl groups, can alter starch gelatinization and enzymatic hydrolysis behavior through hydrogen bonding, thereby regulating digestive properties. Nano-selenium (SeNPs) possess both high bioactivity and low toxicity, and can be stabilized by polyphenol reduction to form a complex. This complex combines the antioxidant properties of polyphenols with the physiological activity of selenium, and has abundant surface hydroxyl groups, demonstrating the potential for interaction with starch.

[0005] Existing research mainly focuses on the modification of starch by single polyphenols or nano-selenium, and has not systematically explored the differential regulation of starch digestibility by polyphenol-nano-selenium complexes with different structures. There is a lack of mild, safe and targeted technical solutions for regulating the fast / slow digestibility of starch, which makes it difficult to meet the diversified development needs of functional foods. Summary of the Invention

[0006] The purpose of this invention is to provide a polyphenol-nano selenium modified starch composite, its preparation method and application. It uses polyphenol-nano selenium particles as the core modifier and utilizes the hydrogen bond interaction between the surface hydroxyl properties and starch molecules to mildly modify starch, thereby obtaining differentiated digestibility characteristics (the trend of regulating rapid and slow digestion).

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A method for preparing a polyphenol-nano-selenium modified starch composite, characterized by comprising the following steps:

[0009] Step 1: Preparation of RSV-SeNPs and PTS-SeNPs, specifically including the following steps:

[0010] (1) Weigh 0.01 g of resveratrol (RSV) and pterostilbene (PTS) into beakers, add 10 mL of phosphate buffer, and stir until completely dissolved to obtain resveratrol solution;

[0011] (2) Take 40 mL of 50 mM / L sodium selenate solution and slowly add it to the above resveratrol and pterostilbene solutions under stirring to make the solutions mix evenly;

[0012] (3) Add 10 mL of 50.5 mg / mL ascorbic acid solution to the mixed solution and stir well;

[0013] (4) Place the reaction system in a 40℃ water bath and stir for 1.0 h. During the reaction, the solution color gradually turns red, indicating that the nano-selenium particles have been generated.

[0014] (5) After the reaction is complete, the product is centrifuged at 10000 r / min for 30 min, the supernatant is discarded, and the precipitate is washed three times with deionized water to remove unreacted raw materials and by-products.

[0015] (6) The washed precipitate was placed in a freeze dryer and freeze-dried for 48 h to obtain red powder, which is RSV-SeNPs and PTS-SeNPs;

[0016] Step 2: Preparation of RSV-SeNPs and PTS-SeNPs modified starch complexes, specifically including the following steps:

[0017] (1) Weigh 1 g of potato starch (PS), 0.1 g of RSV-SeNPs and PTS-SeNPs respectively and mix them in 16 mL of deionized water to obtain a suspension;

[0018] (2) Heat the suspension at 95°C for 30 min until it is completely gelatinized, and then cool it naturally to room temperature to obtain a mixture;

[0019] (3) The treated mixture was freeze-dried for 48 h, then pulverized and passed through a 100-mesh sieve to obtain RSV-SeNPs and PTS-SeNPs modified starch complex.

[0020] This invention can directionally prepare two types of functionalized starch:

[0021] RSV-SeNPs modified starch: mainly slow digestion, with a moderate hydrolysis rate, suitable for functional foods that control sugar and promote satiety;

[0022] PTS-SeNPs modified starch: mainly for rapid digestion, with a high hydrolysis rate, suitable for foods that provide rapid energy.

[0023] The present invention has the following beneficial effects:

[0024] 1. This invention derives the directional and controllable influence on the internal structure of starch by comparing the interfacial interaction strength of two types of particles (high hydroxyl density vs. relatively low hydroxyl density), thereby achieving repeatable regulation of digestibility characteristics.

[0025] 2. This invention focuses the modification on the surface properties and interfacial effects of polyphenol-nanose selenium particles, rather than just describing changes in starch structure, thereby improving the explanatory power and controllability of the modification mechanism.

[0026] 3. This invention constructs an integrated characterization-functional closed loop: by means of FT-IR, XRD, 13C CP / MAS NMR and other methods, it quantitatively reveals how the particle interface interaction is transformed into changes in the SDS / RDS ratio and hydrolysis rate, with a more complete chain of evidence.

[0027] 4. This invention is the first to utilize the difference in the number of hydroxyl groups on the surface of RSV-SeNPs and PTS-SeNPs to achieve differentiated and controllable modification of starch with long-range crystallization and short-range ordered structure. The structural evolution law is clear and the modification mechanism is well understood.

[0028] 5. This invention uses a mild compounding method, which does not require harsh conditions such as high temperature, strong acid, or strong alkali, does not damage the starch molecular skeleton, has high safety, and is suitable for food and health product systems.

[0029] 6. This invention, while regulating starch structure and digestibility, introduces the synergistic function of polyphenols and nano-selenium, which can endow the starch system with certain antioxidant activity and enhance the added value of the product.

[0030] 7. The invention has a clear application prospect: the two types of functionalized starch can respectively meet the needs of slow digestion / fast digestion, and are suitable for sugar-controlled, satiety-type foods and rapid energy supply-type foods, and have cross-field application potential. Attached Figure Description

[0031] Figure 1 These are structural and morphological characterization diagrams of RSV-SeNPs and PTS-SeNPs in embodiments of the present invention;

[0032] Figure 2 The potential and particle size of RSV-SeNPs and PTS-SeNPs in the embodiments of the present invention;

[0033] Figure 3 The XRD patterns of RSV-SeNPs and PTS-SeNPs in this embodiment of the invention are shown.

[0034] Figure 4 The following are the FT-IR infrared spectra of RSV-SeNPs and PTS-SeNPs in the embodiments of the present invention;

[0035] Figure 5 XPS spectra of RSV-SeNPs and PTS-SeNPs in this embodiment of the invention;

[0036] Figure 6 Bioactivity analysis of RSV-SeNPs and PTS-SeNPs in the embodiments of the present invention;

[0037] Figure 7 The XRD patterns of the original starch, RSV-SeNPs and PTS-SeNPs modified starch complexes in the embodiments of the present invention are shown below.

[0038] Figure 8 The images show the FT-IR infrared spectra of native starch and two modified starch complexes in the embodiments of the present invention.

[0039] Figure 9 The images show the 13C CP / MAS NMR spectra of native starch and two modified starch complexes in the embodiments of the present invention.

[0040] Figure 10 The in vitro digestion rate in this embodiment of the invention (left); the components of PS, RSV-SeNPs@PS and PTS-SeNPs@PS (right). Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0042] This invention uses RSV-SeNPs (high hydroxyl density) and PTS-SeNPs (lower hydroxyl density) as controls to analyze the influence of interfacial interaction strength on starch structure evolution.

[0043] Key points for interpreting characterization results:

[0044] RSV-SeNPs: FT-IR hydroxyl peak changes, weakening of long-range crystallization in XRD, weakening of crystallization signal in NMR, and bias towards slow digestion (SDS-dominated) in in vitro digestion tests.

[0045] PTS-SeNPs: The same characterization showed a more pronounced depolymerization trend, NMR / XRD indicated increased fragility of the crystal regions, and in vitro digestion tests showed a bias towards rapid digestion (RDS-dominated).

[0046] By comparison, it is clear that the "modified subject" is the core driver, starch is just a receptor, and the structural changes come from the difference in the intensity of interaction at the particle interface, thereby achieving the directionality of functional output.

[0047] in,

[0048] FT-IR: Changes in the hydroxyl peak and other characteristic peaks demonstrate that the hydrogen bond network at the starch-granule interface has been rearranged or partially broken, indicating that the modification occurs at the molecular level through interfacial interactions.

[0049] XRD: Changes in the crystallization characteristics of starch were observed, indicating the degree and direction of modification in the long-range crystallization region; at the same time, attention was paid to the relative changes in the short-range ordered structure, reflecting the influence of interfacial interactions on the local structure.

[0050] 13 C CP / MAS NMR: Used to qualitatively / quantitatively assess the relative intensity changes of crystalline region signals and short-range ordered signals, further supporting structural evolution caused by interfacial interactions.

[0051] In vitro digestion studies: The modified products are evaluated in an in vitro digestion model to obtain the trend of their impact on rapid and slow digestion, providing functional evidence for applications.

[0052] Example 1: Preparation of RSV-SeNPs and PTS-SeNPs

[0053] (1) Weigh 0.01 g of resveratrol (RSV) and pterostilbene (PTS) into beakers, add 10 mL of phosphate buffer, and stir until completely dissolved to obtain resveratrol solution;

[0054] (2) Take 40 mL of 50 mM / L sodium selenate solution and slowly add it to the above resveratrol and pterostilbene solutions under stirring to make the solutions mix evenly;

[0055] (3) Add 10 mL of 50.5 mg / mL ascorbic acid solution to the mixed solution and stir well;

[0056] (4) The reaction system was placed in a 40℃ water bath and stirred at a constant temperature for 1.0 h. During the reaction, the solution gradually turned red, indicating that the nano-selenium particles had been generated.

[0057] (5) After the reaction is complete, the product is centrifuged at 10000 r / min for 30 min, the supernatant is discarded, and the precipitate is washed three times with deionized water to remove unreacted raw materials and by-products.

[0058] (6) The washed precipitate was placed in a freeze dryer and freeze-dried for 48 h to obtain red powder, namely RSV-SeNPs and PTS-SeNPs.

[0059] After testing, such as Figure 1 As shown, both types of selenium nanoparticles were successfully formed, clearly demonstrating that the products are morphologically independent and have well-defined boundaries at the nanoscale. Among them, RSV-SeNPs are regular spherical with smooth surfaces, concentrated particle size distribution, and good dispersibility; while PTS-SeNPs are mainly rod-shaped particles, with slight aggregation of multiple particles visible in local areas, and their dispersion uniformity is slightly lower than that of RSV-SeNPs.

[0060] like Figure 2 As shown, RSV-SeNPs have uniform particle size and better dispersion stability, while PTS-SeNPs have smaller particle size but slightly poorer uniformity. Both are negatively charged. The differences in polyphenol substituents significantly regulate the particle size, polydispersity index and surface potential of the selenium nanoparticles.

[0061] like Figure 3 As shown, sodium selenite exhibits typical crystalline diffraction peaks, while RSV-SeNPs and PTS-SeNPs both show amorphous broadened diffraction peaks, confirming that both polyphenols were successfully modified to prepare amorphous selenium nanoparticles.

[0062] like Figure 4 As shown, Fourier transform infrared spectroscopy confirmed that both resveratrol and pterostilbene successfully prepared selenium nanoparticles through redox reactions, and the difference in substituents led to significant differences in the interaction strength between the two and the selenium nanoparticles.

[0063] like Figure 5 As shown, XPS results confirmed that both RSV-SeNPs and PTS-SeNPs were successfully synthesized, and due to differences in polyphenol substituents, the two showed significant differences in surface chemical composition, selenium valence state distribution, and binding strength.

[0064] like Figure 6 As shown, both RSV-SeNPs and PTS-SeNPs exhibit good concentration-dependent antioxidant activity. Among them, RSV-SeNPs showed significantly higher scavenging rates of H2O2 and ABTS free radicals than PTS-SeNPs, demonstrating superior antioxidant capacity.

[0065] Example 2 Preparation of RSV-SeNPs and PTS-SeNPs modified starch complexes

[0066] 1 g of potato starch (PS), 0.1 g of RSV-SeNPs, and 0.1 g of PTS-SeNPs were weighed and mixed in 16 mL of deionized water. The suspension was heated at 95 °C for 30 min until completely gelatinized, and then allowed to cool naturally to room temperature. The treated mixture was freeze-dried for 48 h, pulverized after drying, and passed through a 100-mesh sieve to obtain the RSV-SeNPs and PTS-SeNPs modified starch complex.

[0067] like Figure 7 As shown, native starch exhibits typical B-type crystallization characteristic peaks; the intensity of the B-type peaks of the two complexes decreases and the peak shape broadens, and short-range ordered weak diffraction peaks appear at 2θ≈23° and 29°.

[0068] like Figure 8 As shown, compared to the original starch, the intensity of the hydroxyl characteristic peak of the complex is reduced, indicating that the hydrogen bond network between starch molecules is disrupted and new interactions are formed.

[0069] like Figure 9 As shown, the original starch exhibits a distinct crystalline region and double helix characteristic signal at the corresponding chemical shift; after modification, the crystalline signal weakens, while the amorphous and short-range ordered signals are relatively enhanced, and the change trends of the two complexes are significantly different.

[0070] like Figure 10 As shown, the introduction of RSV-SeNPs and PTS-SeNPs altered the digestive behavior of starch, promoting its hydrolysis in a simulated gastrointestinal environment. RSV-SeNPs predominantly consisted of slowly digestible starch (SDS), while PTS-SeNPs predominantly consisted of slowly digestible starch (RDS), resulting in increased hydrolysis rates.

[0071] Table 1. Particle size, zeta potential, and polydispersity index (PDI) of RSV-SeNPs and PTS-SeNPs.

[0072] RSV-SeNPs 452.33±70.61 -28.30±1.34 0.24±0.06 PTS-SeNPs 422.23±45.75 -29.03±0.28 0.30±0.13

[0073] As shown in Table 1, in terms of particle size and dispersibility, the average particle size of PTS-SeNPs (422.23 nm) is smaller than that of RSV-SeNPs (452.33 nm), but the polydispersity index (PDI=0.24) of RSV-SeNPs is significantly lower than that of PTS-SeNPs (PDI=0.30). This indicates that RSV-SeNPs have more uniform particle size and better dispersion stability. Regarding surface charge, both exhibit strong negative potentials, consistent with the characteristics of stable colloidal systems.

[0074] Table 2 Fitting data of C-1 peaks for PS, RSV-SeNPs@PS, and PTS-SeNPs@PS

[0075] PS 75.87% 24.13% RSV-SeNPs 79.05% 20.95% PTS-SeNPs 84.23% 15.77%

[0076] Further fitting analysis of the C-1 peak was performed, and the fitting data are shown in Table 2. In RSV-SeNPs, RSV contains three free phenolic hydroxyl groups, which can form strong hydrogen bonds with starch molecules. While gently disrupting the long-range double-helix crystalline region of starch, it stabilizes the local short-range ordered helical structure. Therefore, the proportion of the helical region slightly increased from 75.87% of pure starch to 79.05%, while the proportion of the amorphous region decreased from 24.13% to 20.95%. The intensity of the -OH stretching vibration peak in FT-IR weakened, reflecting the rearrangement of the hydrogen bond network. The characteristic B-type peak in XRD weakened, but the short-range ordered peak was obvious, which is consistent with the result of the increased proportion of the helical region. In PTS-SeNPs, PTS contains methoxy substituents, resulting in weak hydrogen bonding with starch. This weakens the long-range and short-range ordered structure of starch, causing the original regular crystals of starch to transform into a large number of loose and random helical structures. Consequently, the proportion of helical regions increases significantly to 84.23%, while the proportion of amorphous regions decreases to 15.77%. The area of ​​the -OH peak in FT-IR is significantly reduced, indicating that the starch hydrogen bond network is greatly disrupted. The B-type characteristic peak in XRD has basically disappeared, and the short-range ordered peak is weak. These results corroborate each other.

[0077] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a polyphenol-nano selenium-modified starch composite, characterized in that, Includes the following steps: Step 1: Prepare resveratrol-selenium nanoparticles (RSV-SeNPs) and pterostilbene-selenium nanoparticles (PTS-SeNPs) separately; Step 2: The RSV-SeNPs and PTS-SeNPs are mixed with starch respectively, and then gelatinized, dried and pulverized to obtain RSV-SeNPs modified starch complex and PTS-SeNPs modified starch complex respectively.

2. The preparation method according to claim 1, characterized in that, Step one specifically includes: (1) Weigh 0.01 g of resveratrol and pterostilbene respectively, add 10 mL of phosphate buffer and stir to dissolve, to obtain resveratrol solution and pterostilbene solution; (2) Measure 40 mL of 50 mM / L sodium selenate solution and slowly add it to the two solutions mentioned above under stirring, and mix them evenly; (3) Add 10 mL of 50.5 mg / mL ascorbic acid solution to the mixed solution and stir evenly; (4) Place the reaction system in a 40℃ water bath and stir for 1.0 h; (5) After the reaction is completed, centrifuge at 10000 r / min for 30 min, discard the supernatant, and wash the precipitate with deionized water 3 times; (6) Freeze-dry the washed precipitate for 48 h to obtain red powder, which is RSV-SeNPs and PTS-SeNPs.

3. The preparation method according to claim 1, characterized in that, In step two, the starch is potato starch.

4. The preparation method according to claim 1, characterized in that, Step two specifically includes: (1) Weigh 1 g of potato starch and 0.1 g of RSV-SeNPs or PTS-SeNPs respectively, mix them in 16 mL of deionized water to obtain a suspension; (2) Heat the suspension at 95°C for 30 min until it is completely gelatinized, and then let it cool naturally to room temperature; (3) Freeze-dry the cooled mixture for 48 h, pulverize it after drying, and pass it through a 100-mesh sieve to obtain RSV-SeNPs modified starch complex or PTS-SeNPs modified starch complex.

5. The polyphenol-nano-selenium modified starch composite prepared by the preparation method according to any one of claims 1-4, characterized in that, The composite uses polyphenol-selenium nanoparticles as the core modifier, and modifies starch through hydrogen bonding interactions between the hydroxyl groups on the surface of the polyphenol-selenium nanoparticles and starch molecules.

6. The polyphenol-nano-selenium modified starch composite according to claim 5, characterized in that, The RSV-SeNPs modified starch complex is mainly digested slowly with a moderate hydrolysis rate, making it suitable for functional foods that control sugar intake or provide satiety.

7. The polyphenol-nano-selenium modified starch composite according to claim 5, characterized in that, The PTS-SeNPs modified starch complex is primarily digestible with a high hydrolysis rate, making it suitable for foods that provide rapid energy.

8. The application of the polyphenol-nano selenium modified starch composite according to any one of claims 5-7 in the preparation of functional foods.

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