Starch-plant polyphenol co-crystal, preparation method thereof and application thereof in functional food
By using low-temperature impact milling technology to form a eutectic structure between starch and plant polyphenols, the problems of polyphenol stability and sustained release are solved, achieving long-term release and efficient encapsulation of polyphenols, which is suitable for functional foods.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANCHANG UNIV
- Filing Date
- 2026-01-14
- Publication Date
- 2026-05-26
AI Technical Summary
In existing technologies, polyphenols such as proanthocyanidins have poor physicochemical stability, resulting in low bioavailability. The starch-polyphenol complexes prepared by traditional solution compounding methods have low binding rates and unstable structures, making it difficult to achieve effective sustained-release effects.
Low-temperature impact milling and mechanochemical grinding technology are used to form a co-crystal structure between starch and plant polyphenols. Through starch molecular chain breakage and low-temperature melting penetration, a physically embedded co-crystal structure is formed, which improves the stability and sustained-release performance of polyphenols.
It significantly improves the stability and sustained-release properties of polyphenols, achieving long-term release of polyphenols. It is suitable for functional foods such as low glycemic index steamed buns, and the preparation process is simple and efficient, preserving the activity of polyphenols.
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Figure CN122074652A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of functional food technology, specifically relating to a starch-plant polyphenol co-crystal, its preparation method, and its application in functional foods. In particular, it relates to the technology of using mechanical chemical grinding to form a co-crystal structure between starch and proanthocyanidins to improve the stability and sustained-release properties of polyphenols, and applying this co-crystal to functional flour products such as low glycemic index steamed buns. Background Technology
[0002] Polyphenols (especially proanthocyanidins) have attracted much attention in the development of functional foods for the prevention of chronic diseases due to their significant antioxidant, anti-inflammatory, antibacterial, and metabolic regulatory functions. Studies have shown that the antioxidant capacity of proanthocyanidins is 20 times that of vitamin C and 50 times that of vitamin E. However, their practical application is limited by their poor physicochemical stability and pharmacokinetic defects, resulting in a bioavailability that is often less than 5%, which seriously restricts the sustained efficacy. Starch, as an ideal delivery carrier, can form V-shaped single-helix inclusion complexes with polyphenols through hydrogen bonding and hydrophobic interactions. Recent studies have found that this complex structure can significantly enhance the performance of polyphenols. However, starch-polyphenol complexes prepared by traditional solution-based compounding methods have obvious defects, such as a compounding rate that is usually less than 30% and a tendency for crystal structure to collapse during hydrothermal treatment. This is mainly because the solution method makes it difficult to precisely control the degree of starch gelatinization, resulting in insufficient exposure of polyphenol binding sites. Mechanochemical milling offers a novel approach to solving these problems. This technology induces amorphization on the surface of starch granules through mechanical forces such as shear force and impact energy, causing starch molecular chains to break and expose more free hydroxyl groups. This generates localized high temperatures that promote the melting and penetration of polyphenols, forming mechanical activation sites that guide co-crystallization. The development of hypoglycemic steamed buns using co-crystallization is expected to reduce the starch digestibility rate (eGI) by more than 20%, providing a transformative solution for the industrial production of functional staple foods.
[0003] Chinese patent CN201610231125.4 prepares starch-polyphenol composite nanoparticles through pullulanase enzymatic hydrolysis, alcohol titration, and freeze-drying. This process involves complex separation operations such as ultrafiltration and centrifugation, and relies on room-temperature oscillation adsorption, limiting polyphenol loading efficiency and binding stability. Chinese patent CN201611008242.0 stops enzymatic hydrolysis and pregelatinizes starch by high-temperature heating, combined with ultra-high pressure treatment to enhance apple polyphenol binding capacity. While this improves polyphenol stability, the high temperature may affect the activity of some heat-sensitive polyphenols, and it does not form a co-crystal structure with sustained-release properties. Chinese patent CN202411479866.5 requires multiple physical field treatments, including thermal gelatinization, microfluidization, ball milling, and high-temperature reaction, making the process cumbersome and energy-intensive. It focuses on the construction of the nanonetwork but does not highlight the stable and sustained-release advantages unique to co-crystals. Chinese patent CN202210027279.7 uses high amylose corn starch as a substrate and enhances the antibacterial effect through branching enzyme modification, but its core lies in reducing the GI value and antibacterial function, and it does not adequately optimize the sustained-release performance of polyphenols. Summary of the Invention
[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a starch-plant polyphenol co-crystal, its preparation method, and its application in functional foods. This invention utilizes mechanochemical milling to form a co-crystal structure between wheat starch and plant polyphenols (such as proanthocyanidins), significantly improving the stability and sustained-release properties of the plant polyphenols. Simultaneously, this invention also provides the application of this co-crystal in functional foods, particularly in functional flour products such as low-glycemic index steamed buns, to meet consumer demand for healthy functional foods.
[0005] This invention innovatively employs a co-crystal structure formed by starch and plant polyphenols (such as proanthocyanidins). The principle involves the mechanochemical action of a low-temperature impact mill, which breaks down starch molecular chains and exposes free hydroxyl groups. Simultaneously, the plant polyphenols partially melt at low temperatures and permeate into the helical cavities or amorphous regions of the starch, forming a composite system with a stable encapsulation structure. This structure achieves the sustained release and stabilization of polyphenols through physical encapsulation rather than traditional chemical bonding, belonging to a physical co-crystal form, possessing clear process controllability and structural characteristics. Furthermore, the preparation process of this invention is simpler and more efficient, eliminating the need for complex physical field treatments or multiple freeze-drying steps, and maximizing the preservation of polyphenol activity. The co-crystal structure endows the carrier with excellent sustained-release performance, enabling long-term release of polyphenols in functional food applications. This solves the problems of unstable loading rates and poor sustained-release effects in existing technologies, while also exhibiting higher structural stability and functional activity retention, making its application value in the functional food field even more prominent.
[0006] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing starch-plant polyphenol cocrystals, comprising the following steps: S1. Mix starch and plant polyphenols evenly to obtain a mixture; S2. Add the mixture to a low-temperature impact mill, add grinding media, and introduce inert gas into the low-temperature impact mill to subject the mixture to impact treatment so that starch and plant polyphenols undergo a co-crystallization reaction. S3. The co-crystal complex is purified and freeze-dried to obtain starch-plant polyphenol co-crystal.
[0007] This invention innovatively employs a low-temperature impact mill to process a mixture of starch and plant polyphenols. On one hand, an inert gas is introduced into the mill to maintain an inert environment and low temperature, reducing starch oxidation and plant polyphenol degradation. On the other hand, through grinding and impact, starch molecular chains break down, exposing free hydroxyl groups. Simultaneously, the low temperature promotes the melting and penetration of plant polyphenol molecules into the helical cavities or amorphous regions of the starch, thereby forming a starch-plant polyphenol co-crystal structure. Therefore, this invention can embed plant polyphenol molecules into the helical cavities or amorphous regions of starch to form a co-crystal, utilizing starch to encapsulate and protect the plant polyphenols, improving their bioavailability and achieving long-term release.
[0008] Optionally, in S1, the starch is at least one of wheat starch, corn starch, and potato starch, and the plant polyphenol is at least one of proanthocyanidins, tea polyphenols, and apple polyphenols.
[0009] Optionally, in S1, the mass ratio of starch to plant polyphenols is 1:0.1 to 1:0.3, and the method of mixing evenly is stirring, and the stirring time is 20 to 40 minutes.
[0010] Optionally, in S2, the temperature of the low-temperature impact mill is maintained below -40°C.
[0011] Optionally, in S2, the grinding media is zirconia balls with a particle size of 3-5 mm, the mass ratio of the mixture to the grinding media is 1:5 to 1:10, and the rotation speed of the grinding media is 300-500 rpm.
[0012] Optionally, in S2, the feed rate of the mixture is 5-10 kg / h, the impact treatment time is 10-20 min, and the inert gas flow rate is 5-15 L / min.
[0013] Optionally, the particle size of the eutectic composite treated in S2 should be controlled below 10 μm (i.e., D). 90 ≤10μm), where D 50≤5μm, and the particle size distribution should be relatively concentrated (polydispersity index PDI ≤ 0.3); Secondly, the present invention provides a starch-plant polyphenol cocrystal, which is obtained by the preparation method described above.
[0014] The starch-plant polyphenol cocrystal prepared by this invention has a composite rate or encapsulation rate of about 55%, thereby realizing the encapsulation and protection of plant polyphenols by starch, improving the bioavailability of plant polyphenols, and achieving long-term release of plant polyphenols.
[0015] Thirdly, the present invention provides the application of the starch-plant polyphenol cocrystal in the preparation of functional foods.
[0016] The starch-plant polyphenol co-crystal structure of the present invention endows the carrier with excellent sustained-release properties, enabling long-term release of polyphenols in functional food applications.
[0017] Optionally, the functional food is a low glycemic index food.
[0018] Specifically, starch-plant polyphenol cocrystals can be used to prepare functional flour products such as low glycemic index steamed buns.
[0019] Fourthly, the present invention provides the application of the starch-plant polyphenol cocrystal in the preparation of antioxidant health products or pharmaceuticals.
[0020] The plant polyphenols of the present invention, such as proanthocyanidins, have antioxidant effects. Therefore, the starch-plant polyphenol cocrystal of the present invention can be used to prepare antioxidant health products or pharmaceuticals to achieve long-term release of plant polyphenols such as proanthocyanidins.
[0021] This invention has at least one of the following beneficial effects: (1) The present invention uses a low-temperature impact mill mechanical chemical grinding technology to make starch and plant polyphenols form a eutectic structure, which significantly improves the stability and sustained-release performance of polyphenols.
[0022] (2) The preparation process of the present invention does not require chemical reagents and is safe and environmentally friendly.
[0023] (3) The starch-plant polyphenol cocrystal prepared by the present invention can be widely used in functional foods, such as low glycemic index foods, which are suitable for people with diabetes, hyperglycemia and other conditions, and have significant health benefits.
[0024] (4) The starch-plant polyphenol cocrystal prepared by the present invention can also be used in the preparation of antioxidant health products or medicines to achieve long-term release of plant polyphenols such as proanthocyanidins. Attached Figure Description
[0025] Figure 1This is a flowchart illustrating the preparation process of wheat starch-plant polyphenol cocrystal in an embodiment of the present invention.
[0026] Figure 2 This is a schematic diagram of the low-temperature impact mill in Embodiment 1 of the present invention.
[0027] Figure 3 The above are the hydrolysis curves of the eutectic prepared in Example 1 and Comparative Example 1 of this invention.
[0028] Figure 4 The results are the glycemic index test results of the steamed buns prepared in Example 2 and Comparative Example 2 of this invention. Detailed Implementation
[0029] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0030] Example 1 A method for preparing wheat starch-plant polyphenol cocrystals, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps: Step 1: Select 15 kg of wheat starch extracted from high-quality strong gluten wheat produced in Henan Province for later use. Weigh out 3 kg of proanthocyanidins with a purity of 95% for later use; Step 2: Mix 15 kg of wheat starch with 3 kg of proanthocyanidins evenly and stir for 30 min to obtain a mixture.
[0031] Step 3: Add the mixture to a commercially available low-temperature impact mill. The schematic diagram of the low-temperature impact mill is shown below. Figure 2 As shown; the feed rate of the mixture is 5 kg / h, the grinding chamber temperature is controlled at -40℃, zirconia balls (particle size 3~5 mm) are added as grinding media, the mass ratio of the mixture to the grinding media is 1:5, the grinding media rotation speed is 400 rpm, inert gas (nitrogen) is introduced during the grinding process to maintain the inert environment in the chamber, the gas flow rate is 10 L / min to reduce starch oxidation and proanthocyanidin degradation, the impact time is 15 min, and a co-crystal complex is obtained; Step 3: Wash and purify the co-crystal complex (wash with cold anhydrous ethanol to remove unbound proanthocyanidins), collect the precipitate by centrifugation, and freeze-dry to obtain the final co-crystal; Step 4: Perform performance testing on the prepared eutectic.
[0032] The eutectic composite treated with low-temperature impact milling should meet the following physical properties: Regarding particle size distribution, measured using a laser particle size analyzer, D... 50≤ 5μm, D 90 ≤ 10μm; Scanning electron microscopy (SEM) observation showed that the particles were irregularly plate-like or spherical, with no obvious aggregation on the surface; X-ray diffraction (XRD) patterns showed obvious diffraction peaks near 2θ = 13°, 20°, and 22°, indicating the formation of a V-shaped crystalline structure; Differential scanning calorimetry (DSC) detected that the melting peak shifted towards the high temperature direction, indicating that the eutectic structure was stable.
[0033] Example 2 A method for preparing a low glycemic index steamed bun includes the following steps: Step 1: Take 500 g of wheat starch-proanthocyanidin cocrystals prepared in Example 1, add 5 g of arabinoxylan (addition amount is 1%), add an appropriate amount of water (mass ratio of flour to water is 1:0.5), add 5 g of yeast, and mix in a dough mixer for 10-15 min to form a smooth dough.
[0034] Step 2: Place the dough in an environment of 30℃ and 85% humidity to ferment for 1-2 hours, until the dough volume expands to about twice its original size.
[0035] Step 3: Take out the fermented dough, deflate it, divide it into several small portions, knead them into the shape of steamed buns, put them in a steamer, and let them rise for 20-30 minutes at 30℃ and 85% humidity.
[0036] Step 4: After proofing, steam over high heat for 15-20 minutes, turn off the heat and let it sit for 3-5 minutes before taking it out to get low glycemic index steamed buns.
[0037] Comparative Example 1 The traditional solution method for preparing starch-proanthocyanidin complex includes the following steps: Step 1: Weigh out 15 kg of wheat starch and 3 kg of proanthocyanidins, the same as in Example 1.
[0038] Step 2: Add wheat starch to an appropriate amount of water to prepare a 10% starch solution. Heat to 60°C and stir until the starch is completely gelatinized. Then add proanthocyanidins and continue stirring for 30 minutes to ensure the proanthocyanidins are fully mixed with the starch.
[0039] Step 3: The mixed solution is spray-dried (inlet temperature 180℃, outlet temperature 80℃) to obtain starch-proanthocyanidin complex.
[0040] Step 4: Perform performance testing on the prepared composite.
[0041] Comparative Example 2 The traditional method for preparing steamed buns without added proanthocyanidins includes the following steps: Step 1: Take 500 g of regular wheat flour, add 5 g of arabinoxylan, add an appropriate amount of water (the mass ratio of flour to water is 1:0.5), and then add 5 g of yeast. Mix in a dough mixer for 10-15 minutes to form a smooth dough.
[0042] Step 2: Follow steps 2-4 in Example 2 to obtain traditional steamed buns.
[0043] Comparative Example 3 The difference from Example 1 is that a "common ball mill" is used instead of a "low-temperature impact mill". The processing parameters of the common ball mill are: grinding temperature 25°C, no inert gas is introduced, the grinding media is 3-5 mm zirconia balls, the mass ratio of the mixture to the grinding media is 1:5, the rotation speed is 400 rpm, the feed rate is 10 kg / h, and the grinding time is 15 min.
[0044] Everything else is the same as in Example 1.
[0045] Then, steamed buns were prepared according to the method in Example 2.
[0046] Comparative Example 4 The difference from Example 1 is that the "impact time" in step 2 is changed to 5 minutes, while the rest is the same as in Example 1.
[0047] Then, steamed buns were prepared according to the method in Example 2.
[0048] Comparative Example 5 The difference from Example 1 is that the "impact time" in step 2 is changed to 25 minutes, while the rest is the same as in Example 1.
[0049] Then, steamed buns were prepared according to the method in Example 2.
[0050] Comparative Example 6 The difference from Example 1 is that the "grinding media speed" in step 2 is changed to 100 rpm, while the rest is the same as in Example 1.
[0051] Then, steamed buns were prepared according to the method in Example 2.
[0052] Comparative Example 7 The difference from Example 1 is that the "grinding media speed" in step 2 is changed to 700 rpm, while the rest is the same as in Example 1.
[0053] Then, steamed buns were prepared according to the method in Example 2.
[0054] Comparative Example 8 The difference from Example 1 is that the "grinding chamber temperature" in step 2 is changed to -20℃, while the rest is the same as in Example 1.
[0055] Then, steamed buns were prepared according to the method in Example 2.
[0056] The properties of the substances prepared in Examples 1-2 and Comparative Examples 1-8 were measured and characterized.
[0057] 1. The hydrolysis rates of the cocrystal prepared in Example 1, the complex prepared in Comparative Example 1, and the substances prepared in Comparative Examples 3-8 were determined. The determination method was as follows: 0.5 g of sample (cocrystal prepared in Example 1, Comparative Example 1, and Comparative Examples 3-8) was accurately weighed, 20 mL of acetate-sodium acetate buffer solution at pH 5.2 was added, and the mixture was placed in a 37℃ constant temperature water bath for 10 min to equilibrate. 1 mL of α-amylase (activity 1000 U / mL) was added, and the reaction was shaken. 2 mL samples were taken at 0, 20, 40, 60, 80, 100, 120, 160, and 180 min, respectively, and the reaction was immediately terminated by adding 1 mL of 0.5 mol / L HCl solution. The reducing sugar content was determined by the DNS method, and the hydrolysis rate was calculated.
[0058] Hydrolysis rate (%) = (mass of reducing sugars generated / mass of reducing sugars generated from complete hydrolysis of starch in the sample) × 100%.
[0059] The results are as follows Figure 3 As shown in Table 1, Figure 1 The hydrolysis curves show that the starch-plant polyphenol cocrystal prepared in Example 1 of this invention exhibits a significantly delayed hydrolysis rate during in vitro digestion, and its final hydrolysis rate is significantly lower than that of Comparative Example 1 (conventional solution method complex). Table 1 shows that the final hydrolysis rate of Example 1 is also significantly lower than that of Comparative Examples 3-8 (control groups with different process parameters), indicating that the cocrystal structure effectively inhibits the hydrolysis of starch by amylase, demonstrating good slow-release and enzymatic resistance.
[0060] Table 1. Hydrolysis rates of Examples 1, Comparative Examples 1 and 3-8 at different time points 2. The encapsulation efficiency of the cocrystal prepared in Example 1, the complex prepared in Comparative Example 1, and the substances prepared in Comparative Examples 3-8 was determined. The determination method was as follows: a certain mass (m1, approximately 0.1 g) of dried sample was accurately weighed, 10 mL of 70% ethanol solution was added, and the mixture was vortexed for 10 minutes to extract the unencapsulated free proanthocyanidins. The sample was then centrifuged at 5000 rpm for 10 minutes. The supernatant was collected, and the absorbance was measured at 760 nm using the Folin-phenol method. The mass of free proanthocyanidins (m2) was calculated according to the proanthocyanidin standard curve. The encapsulation efficiency (EE%) was calculated using the following formula: EE%=[(1 [m2 / (m1×initial proanthocyanidin addition ratio)]×100% The results are shown in Table 2. The encapsulation efficiency of the cocrystal prepared in Example 1 was approximately 55.2%, while the encapsulation efficiency of the composite obtained by the traditional solution method was only 28.5%. Therefore, the encapsulation efficiency of the cocrystal prepared by the method of this invention is much higher than that of the traditional solution method. Similarly, the encapsulation efficiency of the cocrystal prepared in Example 1 was also higher than that of Comparative Examples 3-8 (control groups with different process parameters), indicating that different processing conditions can also affect the encapsulation efficiency.
[0061] Table 2 Comparison of encapsulation rates in Example 1, Comparative Example 1, and Comparative Examples 3-8 3. The glycemic index of the low glycemic index steamed bun prepared in Example 2 and the traditional steamed bun prepared in Comparative Example 2 were determined. The determination method was as follows: Ten healthy volunteers (aged 20-30 years, BMI 18.5-23.9) were selected and fasted for 12 hours before the experiment. The volunteers were given 50 g of samples containing available carbohydrates (steamed buns prepared in Example 2 and Comparative Example 2) and 50 g of glucose (reference material). Venous blood of 2 mL was collected before consumption (0 min) and at 10, 20, 30, 60, 90 and 120 min after consumption. After centrifugation to separate the serum, the blood glucose concentration was determined by glucose oxidase method. The blood glucose-time curve was plotted and the area under the curve (AUC) was calculated.
[0062] Sample GI value = (sample AUC / glucose AUC) × 100 The results are as follows Figure 4 As shown, the low glycemic index steamed bun prepared using the co-crystal of the present invention (Example 2) caused a significantly lower rate and magnitude of blood glucose rise in human trials than the conventional steamed bun (Comparative Example 2) and other comparative example groups. Its calculated GI value decreased by more than 20%, which confirms that the co-crystal has the function of regulating postprandial blood glucose response in real food systems and verifies its application potential in low glycemic index foods.
[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing starch-plant polyphenol cocrystals, characterized in that, Includes the following steps: S1. Mix starch and plant polyphenols evenly to obtain a mixture; S2. Add the mixture to a low-temperature impact mill, add grinding media, and introduce inert gas into the low-temperature impact mill to subject the mixture to impact treatment so that starch and plant polyphenols undergo a co-crystallization reaction to obtain a co-crystallized complex. S3. The co-crystal complex is purified and freeze-dried to obtain starch-plant polyphenol co-crystal.
2. The preparation method according to claim 1, characterized in that, In S1, the starch is at least one of wheat starch, corn starch, and potato starch, and the plant polyphenol is at least one of proanthocyanidins, tea polyphenols, and apple polyphenols.
3. The preparation method according to claim 1, characterized in that, In S1, the mass ratio of starch to plant polyphenols is 1:0.1 to 1:0.3, and the method of mixing evenly is stirring, with the stirring time being 20 to 40 minutes.
4. The preparation method according to claim 1, characterized in that, In S2, the temperature of the low-temperature impact mill is maintained below -40°C, the grinding media is zirconia balls with a particle size of 3~5 mm, the mass ratio of the mixture to the grinding media is 1:5~1:10, and the rotation speed of the grinding media is 300-500 rpm.
5. The preparation method according to claim 1, characterized in that, In S2, the feed rate of the mixture is 5-10 kg / h, the impact treatment time is 10-20 min, and the inert gas flow rate is 5-15 L / min.
6. The preparation method according to claim 1, characterized in that, The D of the co-crystal complex obtained in S2 50 ≤5μm, D 90 ≤10μm.
7. A starch-plant polyphenol cocrystal, characterized in that, It is obtained by the preparation method described in any one of claims 1 to 6.
8. The application of the starch-plant polyphenol cocrystal as described in claim 7 in the preparation of functional foods.
9. The application according to claim 8, characterized in that, The functional food mentioned is a low glycemic index food.
10. The use of the starch-plant polyphenol cocrystal according to claim 7 in the preparation of antioxidant health products or pharmaceuticals.