A preparation method of a starch-polyphenol inclusion complex

Abstract

The present invention provides a method for preparing a starch-polyphenol inclusion complex, which relates to the technical field of the food industry. The method for preparing the starch-polyphenol inclusion complex comprises the following steps: preparing a deep eutectic solvent; wherein, the deep eutectic solvent is food-grade; dissolving polyphenols in the deep eutectic solvent to obtain a polyphenol solution; mixing the polyphenol solution with a gelatinized starch solution, keeping the mixture at 80-100 °C for 20-40 min, then cooling to room temperature, separating and drying the solid matter to obtain the starch-polyphenol inclusion complex. By using a food-grade deep eutectic solvent, the overall product of the present invention meets the requirements of the food industry. At the same time, the deep eutectic solvent can dissolve polyphenols and inhibit the recrystallization of starch, thereby facilitating the formation of the starch-polyphenol inclusion complex driven by temperature changes.

Description

Technical Field

[0001] The present invention relates to the technical field of the food industry, and particularly relates to a method for preparing a starch-polyphenol inclusion complex. Background Art

[0002] After starch and polyphenols are complexed, a starch-polyphenol inclusion complex can be formed, and its structure is similar to that of a starch-lipid inclusion complex. Therefore, the starch-polyphenol inclusion complex also has resistance and is considered to be the fifth type of resistant starch similar to the starch-lipid inclusion complex. In addition, the formation of the starch-polyphenol inclusion complex can also improve the stability of polyphenols.

[0003] Currently, the cooking and gelatinization method is often used to prepare the starch-polyphenol inclusion complex, that is, starch is gelatinized at high temperature and then added to an ethanol solution containing polyphenols, and then the formation of the starch-polyphenol inclusion complex is driven by cooling. However, in fact, when using this method to prepare the starch-polyphenol inclusion complex, starch molecules tend to form a double helix, that is, recrystallize, with starch molecules, rather than complexing with polyphenol molecules to form a single helix inclusion complex.

[0004] Therefore, in the prior art, the dimethyl sulfoxide method and the alkali method are also used to prepare the starch-polyphenol inclusion complex. In the dimethyl sulfoxide method, generally, starch and polyphenols are dissolved in a dimethyl sulfoxide solution at about 90 °C, and the formation of the inclusion complex is driven by adding an appropriate amount of hot water to dilute the solution; in the alkali method, starch and polyphenols are dissolved in a high-temperature sodium hydroxide or potassium hydroxide solution, and then, after acidification, the formation of the inclusion complex is driven.

[0005] Both dimethyl sulfoxide and alkali solution can inhibit starch recrystallization and thus promote the formation of the starch-polyphenol inclusion complex. However, both dimethyl sulfoxide and alkali solution are difficult to be used in the food industry. Therefore, it is necessary to develop a method for preparing a starch-polyphenol inclusion complex without using dimethyl sulfoxide and alkali solution. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a starch-polyphenol inclusion complex. By dissolving polyphenols in a food-grade deep eutectic solvent, and then mixing the polyphenol solution with a gelatinized starch solution and driving the formation of the inclusion complex by cooling, a food-grade starch-polyphenol inclusion complex can be effectively prepared.

[0007] A method for preparing a starch-polyphenol inclusion complex provided by the present invention includes the following steps:

[0008] Prepare a deep eutectic solvent; wherein, the deep eutectic solvent is food-grade;

[0009] Dissolve polyphenols in the deep eutectic solvent to obtain a polyphenol solution;

[0010] Mix the polyphenol solution with the gelatinized starch solution, keep it at 80 - 100 °C for 20 - 40 min, then cool it to room temperature, separate and dry the solid matter to obtain the starch-polyphenol inclusion compound.

[0011] A preparation method of a starch-polyphenol inclusion compound provided by the present invention has the beneficial effect that by using a food-grade deep eutectic solvent, the overall product meets the requirements of the food industry. At the same time, the deep eutectic solvent can dissolve polyphenols and inhibit the recrystallization of starch, thus facilitating the formation of starch-polyphenol inclusion compounds driven by temperature changes.

[0012] Optionally, when preparing the deep eutectic solvent, the deep eutectic solvent includes betaine and citric acid with a molar ratio of 1:1, citric acid and glucose with a molar ratio of 1:1, citric acid and glycerol with a molar ratio of 1:2, or glucose and lactic acid with a molar ratio of 1:5.

[0013] Optionally, when preparing the deep eutectic solvent, when the deep eutectic solvent is betaine and citric acid with a molar ratio of 1:1, it includes the following steps: mix betaine and citric acid at a molar ratio of 1:1 and keep it at 100 °C for 55 - 65 min to obtain the deep eutectic solvent;

[0014] When the deep eutectic solvent is citric acid and glucose with a molar ratio of 1:1, it includes the following steps: mix citric acid and glucose at a molar ratio of 1:1 and keep it at 90 °C for 55 - 65 min to obtain the deep eutectic solvent;

[0015] When the deep eutectic solvent is citric acid and glycerol with a molar ratio of 1:2, it includes the following steps: mix citric acid and glycerol at a molar ratio of 1:2 and keep it at 100 °C for 55 - 65 min to obtain the deep eutectic solvent;

[0016] When the deep eutectic solvent is glucose and lactic acid with a molar ratio of 1:5, it includes the following steps: mix glucose and lactic acid at a molar ratio of 1:5 and keep it at 90 °C for 55 - 65 min to obtain the deep eutectic solvent.

[0017] Optionally, when dissolving polyphenols in the deep eutectic solvent, the polyphenols include one of genistein, quercetin, naringin, gallic acid, ferulic acid, and caffeic acid.

[0018] Optionally, after dissolving polyphenols in the deep eutectic solvent to obtain a polyphenol solution, the concentration of the polyphenols in the polyphenol solution is 0.015 - 0.025 g / mL.

[0019] Optionally, before mixing the polyphenol solution with the gelatinized starch solution, perform the following steps: mix starch and water and disperse them, then heat them in a boiling water bath to obtain the gelatinized starch solution.

[0020] Optionally, after mixing and dispersing starch with water, the concentration of the starch is

[0021] Optionally, after mixing the polyphenol solution with the gelatinized starch solution, the mass ratio of polyphenol in the polyphenol solution to gelatinized starch in the gelatinized starch solution is Description of the Drawings

[0022] Figure 1 It is a flowchart of a method for preparing a starch-polyphenol inclusion complex provided in an embodiment of the present invention;

[0023] Figure 2 It is an X-ray diffraction pattern of the starch-polyphenol inclusion complex prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention. Detailed Description of the Invention

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention belongs. The words such as "including" used herein are intended to mean that the elements or items appearing before this word cover the elements or items listed after this word and their equivalents, without excluding other elements or items.

[0025] The embodiments of the present invention provide a method for preparing a starch-polyphenol inclusion complex, which includes the following steps:

[0026] S1. Prepare a deep eutectic solvent; wherein, the deep eutectic solvent is food-grade;

[0027] S2. Prepare a polyphenol solution: dissolve polyphenol in the deep eutectic solvent to obtain a polyphenol solution;

[0028] S3. Prepare a starch-polyphenol inclusion complex: mix the polyphenol solution with the gelatinized starch solution, keep it at 80-100 °C for 20-40 min, then cool it to room temperature, separate and dry the solid matter to obtain the starch-polyphenol inclusion complex.

[0029] Actually, since the deep eutectic solvent is a food-grade raw material, the prepared starch-polyphenol inclusion complex also meets the food-grade requirements and can be applied to the food industry.

[0030] In some embodiments, when performing step S1, the deep eutectic solvent includes betaine and citric acid with a molar ratio of 1:1, citric acid and glucose with a molar ratio of 1:1, citric acid and glycerol with a molar ratio of 1:2, or glucose and lactic acid with a molar ratio of 1:5.

[0031] Specifically, when preparing the deep eutectic solvent, the betaine, citric acid, glucose, glycerol, and lactic acid selected are all commercially available food-grade products.

[0032] In some embodiments, when the deep eutectic solvent is betaine and citric acid with a molar ratio of 1:1, when performing step S1, it includes the following steps: mixing betaine and citric acid in a molar ratio of 1:1 and keeping it at 100 °C for 55 - 65 min to obtain the deep eutectic solvent.

[0033] In some embodiments, when the deep eutectic solvent is citric acid and glucose with a molar ratio of 1:1, when performing step S1, it includes the following steps: mixing citric acid and glucose in a molar ratio of 1:1 and keeping it at 90 °C for 55 - 65 min to obtain the deep eutectic solvent.

[0034] In some embodiments, when the deep eutectic solvent is citric acid and glycerol with a molar ratio of 1:2, when performing step S1, it includes the following steps: mixing citric acid and glycerol in a molar ratio of 1:2 and keeping it at 100 °C for 55 - 65 min to obtain the deep eutectic solvent.

[0035] In some embodiments, when the deep eutectic solvent is glucose and lactic acid with a molar ratio of 1:5, when performing step S1, it includes the following steps: mixing glucose and lactic acid in a molar ratio of 1:5 and keeping it at 90 °C for 55 - 65 min to obtain the deep eutectic solvent.

[0036] Actually, when any one of the components in any combination of betaine and citric acid, citric acid and glucose, citric acid and glycerol, and glucose and lactic acid is heated alone, its melting point is higher than 100 °C, while after combination, they can form a eutectic at 100 °C to obtain a clear and uniform liquid.

[0037] In some embodiments, after performing step S1, the deep eutectic solvent is naturally cooled to room temperature. Actually, the deep eutectic solvent can also be uniformly cooled to room temperature by means such as water cooling and air cooling.

[0038] In some embodiments, when dissolving polyphenols in the deep eutectic solvent in step S2, the polyphenols include one of genistein, quercetin, naringin, gallic acid, ferulic acid, and caffeic acid. Actually, any specific polyphenol substance of food grade can be selected as the polyphenols, and the specific polyphenols can be selected from commercially available conventional products.

[0039] In some embodiments, when dissolving polyphenols in the deep eutectic solvent in step S2, a single polyphenol can be dissolved in the deep eutectic solvent, or multiple polyphenols can be dissolved in the same deep eutectic solvent, so as to prepare an inclusion complex of starch with multiple polyphenols.

[0040] In some embodiments, after step S2 is executed, the concentration of polyphenols in the polyphenol solution is 0.015 - 0.025 g / mL.

[0041] In some embodiments, referring to Figure 1 , before mixing the polyphenol solution with the gelatinized starch solution in step S3, the following steps are executed:

[0042] S0. Prepare the gelatinized starch solution: Mix starch and water and disperse them, then heat in a boiling water bath to obtain the gelatinized starch solution.

[0043] Actually, after step S0 is executed, the concentration of starch is Specifically, the addition amount of starch is necessary to be able to completely gelatinize and be able to completely include polyphenols.

[0044] In some embodiments, after mixing the polyphenol solution with the gelatinized starch solution in step S3, the mass ratio of polyphenols in the polyphenol solution to gelatinized starch in the gelatinized starch solution is In this way, the gelatinized starch can play a good inclusion role on polyphenols, and at the same time, the deep eutectic solvent in the polyphenol solution can inhibit the recrystallization of the gelatinized starch.

[0045] In some embodiments, after mixing the polyphenol solution with the gelatinized starch solution in step S3, the mixed solution is rapidly stirred at a rotation speed of 15000 - 20000 rpm, so that the polyphenol solution and the gelatinized starch solution are fully mixed, and polyphenols, the deep eutectic solvent and gelatinized starch can fully contact, which is beneficial to the formation of the starch-polyphenol inclusion complex. Specifically, the mixed solution after mixing the polyphenol solution with the gelatinized starch solution can be stirred at a rotation speed of 17000 rpm for 8 - 10 min.

[0046] In some embodiments, after mixing the polyphenol solution with the gelatinized starch solution in step S3, the mixed solution is kept warm in an environment of 80 - 100 °C for 20 - 40 min, and kept stirring to improve the dispersion uniformity of polyphenols and gelatinized starch, and then naturally cooled to room temperature and the solid is separated, and the solid is dried to obtain the starch-polyphenol inclusion complex. Actually, during the cooling process, the inclusion effect of gelatinized starch on polyphenols can be driven.

[0047] In some embodiments, after cooling to room temperature in step S3, the mixed solution is kept warm at room temperature for 2 h to improve the inclusion effect of gelatinized starch on polyphenols.

[0048] In some embodiments, when separating and drying the solid matter in step S3, after centrifuging the mixed solution cooled to room temperature at a speed of 4000 rpm for 15 min, the solid matter is filtered out and dried at 50 °C for 10 min to obtain the starch-polyphenol inclusion complex.

[0049] In some embodiments, when separating and drying the solid matter in step S3, the separated solid matter can be washed with deionized water to remove the polyphenol substances that failed to be included.

[0050] Example 1

[0051] Embodiment 1 of the present invention provides a preparation method of a starch-polyphenol inclusion complex, including the following steps:

[0052] S0. 5.0 g of starch is uniformly dispersed in 90 mL of distilled water and transferred to a boiling water bath for heating for 30 min to completely gelatinize the starch, obtaining a gelatinized starch solution;

[0053] S1. After mixing 117.146 g (1 mol) of betaine and 192.13 g (1 mol) of citric acid, keep it at 100 °C for 1 h to form a uniform and clear eutectic solvent;

[0054] S2. 0.2 g of polyphenol is dissolved in 10 mL of the eutectic solvent, and after stirring and dissolving, a polyphenol solution is obtained; wherein, the polyphenol is specifically genistein;

[0055] S3. The polyphenol solution is added to the gelatinized starch solution, and kept in a water bath environment at 90 °C for 30 min, taken out and naturally cooled to 25 °C and kept for 2 h, centrifuged at a speed of 4000 rpm for 15 min, the solid matter is filtered out and washed and dried to obtain the starch-polyphenol inclusion complex; wherein, the starch-polyphenol inclusion complex is specifically a polyphenol-genistein inclusion complex.

[0056] Example 2

[0057] Embodiment 2 of the present invention provides a preparation method of a starch-polyphenol inclusion complex. The difference from Embodiment 1 is that in step S1, after mixing 19.21 g (0.1 mol) of citric acid and 18.02 g (0.1 mol) of glucose, keep it at 90 °C for 1 h to form a uniform and clear eutectic solvent; in step S2, the polyphenol is specifically quercetin; in step S3, the starch-polyphenol inclusion complex is specifically a polyphenol-quercetin inclusion complex.

[0058] Example 3

[0059] Example 3 of the present invention provides a method for preparing a starch-polyphenol inclusion complex, which is different from Example 1 in that in step S0, 8.0 g of starch is uniformly dispersed in 90 mL of distilled water and transferred to a boiling water bath for heating for 30 min to completely gelatinize the starch, obtaining a gelatinized starch solution; in step S1, 19.21 g (0.1 mol) of citric acid and 18.07 g (0.2 mol) of glycerol are mixed and kept at 100 °C for 1 h to form a homogeneous and clear eutectic solvent; in step S2, the polyphenol is specifically naringin; in step S3, the starch-polyphenol inclusion complex is specifically a polyphenol-naringin inclusion complex.

[0060] Example 4

[0061] Example 4 of the present invention provides a method for preparing a starch-gallic acid inclusion complex, which is different from Example 1 in that in step S1, 45.04 g (0.5 mol) of lactic acid and 18.02 g (0.1 mol) of glucose are mixed and kept at 90 °C for 1 h to form a homogeneous and clear eutectic solvent; in step S2, the polyphenol is specifically gallic acid; in step S3, the starch-polyphenol inclusion complex is specifically a polyphenol-gallic acid inclusion complex.

[0062] Comparative Example 1

[0063] Comparative Example 1 of the present invention provides a method for preparing a starch-polyphenol inclusion complex, which is different from Example 1 in that step S1 is not carried out, and 10 mL of ethanol is used instead of 10 mL of the eutectic solvent in step S2.

[0064] Comparative Example 2

[0065] Comparative Example 2 of the present invention provides a method for preparing a starch-polyphenol inclusion complex, which is different from Example 2 in that step S1 is not carried out, and 10 mL of ethanol is used instead of 10 mL of the eutectic solvent in step S2.

[0066] Comparative Example 3

[0067] Comparative Example 3 of the present invention provides a method for preparing a starch-polyphenol inclusion complex, which is different from Example 3 in that step S1 is not carried out, and 10 mL of ethanol is used instead of 10 mL of the eutectic solvent in step S2.

[0068] Comparative Example 4

[0069] Comparative Example 4 of the present invention provides a method for preparing a starch-polyphenol inclusion complex, which is different from Example 4 in that step S1 is not carried out, and 10 mL of ethanol is used instead of 10 mL of the eutectic solvent in step S2.

[0070] Performance Test

[0071] The starch-polyphenol inclusion complexes prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to crystal structure analysis using an X-ray diffractometer. The specific operation is as follows: A copper target Cu Kα (λ = 0.15406 nm) was selected, with a power of 1600 W (40 kV × 40 mA). An NaI crystal scintillation counter was used to measure the intensity of the X-ray. The scanning range was 4° - 35°, and the scanning speed was 4° / min. The results are as Figure 2 shown.

[0072] The starch-polyphenol inclusion complexes prepared in Examples 1-4 and Comparative Examples 1-4 were dissolved in dimethyl sulfoxide respectively, and the polyphenol content in the inclusion complexes was determined by the Folin-Ciocalteu method. The results are shown in Table 1.

[0073] Table 1 Polyphenol content of the inclusion complexes in Examples 1-4 and Comparative Examples 1-4

[0074] Polyphenol content (mmol / g starch) Polyphenol content (mmol / g starch) Example 1 23.7 Comparative Example 1 2.1 Example 2 17.9 Comparative Example 2 1.2 Example 3 26.2 Comparative Example 3 1.9 Example 4 15.4 Comparative Example 4 1.4

[0075] See Figure 2 It can be seen that the starch-polyphenol inclusion complexes prepared in Examples 1-4 showed diffraction peaks at 7°, 13° and 20°, which were V-type crystals, indicating that starch and polyphenol substances formed inclusion complexes. While the starch-polyphenol inclusion complexes prepared in Comparative Examples 1-4 showed diffraction peaks at 14.3°, 17.0°, 19.6°, 22.0° and 24.1°, which were B+V-type crystals, and the B-type peaks were significantly stronger than the V-type peaks, indicating that in Comparative Examples 1-4, starch tended to recrystallize rather than complex with polyphenols to form inclusion complexes. See Table 1, it can be known that compared with the comparative examples, the method provided in Examples 1-4 can achieve a better and higher inclusion effect on polyphenol substances.

[0076] Although the embodiments of the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are all within the scope and spirit of the present invention described in the claims. Moreover, the present invention described herein can have other embodiments and can be implemented or realized in various ways.

Claims

1. A method for preparing a starch-polyphenol inclusion complex, characterized in that, It includes the following steps: Prepare a deep eutectic solvent; wherein, the deep eutectic solvent is food-grade and includes betaine and citric acid with a molar ratio of 1:1, citric acid and glucose with a molar ratio of 1:1, citric acid and glycerol with a molar ratio of 1:2, or glucose and lactic acid with a molar ratio of 1:5; Dissolve polyphenols in the deep eutectic solvent to obtain a polyphenol solution; Mix the polyphenol solution with the gelatinized starch solution, keep it at 80 - 100 °C for 20 - 40 min, then cool it to room temperature, separate and dry the solid matter to obtain a starch-polyphenol inclusion complex.

2. The preparation method according to claim 1, wherein When preparing the deep eutectic solvent, when the deep eutectic solvent is betaine and citric acid with a molar ratio of 1:1, it includes the following steps: mix betaine and citric acid with a molar ratio of 1:1 and keep it at 100 °C for 55 - 65 min to obtain the deep eutectic solvent; When the deep eutectic solvent is citric acid and glucose with a molar ratio of 1:1, it includes the following steps: mix citric acid and glucose with a molar ratio of 1:1 and keep it at 90 °C for 55 - 65 min to obtain the deep eutectic solvent; When the deep eutectic solvent is citric acid and glycerol with a molar ratio of 1:2, it includes the following steps: mix citric acid and glycerol with a molar ratio of 1:2 and keep it at 100 °C for 55 - 65 min to obtain the deep eutectic solvent; When the deep eutectic solvent is glucose and lactic acid with a molar ratio of 1:5, it includes the following steps: mix glucose and lactic acid with a molar ratio of 1:5 and keep it at 90 °C for 55 - 65 min to obtain the deep eutectic solvent.

3. The preparation method according to claim 1, characterized in that, When dissolving polyphenols in the deep eutectic solvent, the polyphenols include one of genistein, quercetin, naringin, gallic acid, ferulic acid, and caffeic acid.

4. The preparation method according to claim 1 or 3, characterized in that, After dissolving polyphenols in the deep eutectic solvent to obtain a polyphenol solution, the concentration of the polyphenols in the polyphenol solution is 0.015 - 0.025 g / mL.

5. The preparation method according to claim 1, wherein Before mixing the polyphenol solution with the gelatinized starch solution, perform the following steps: mix starch and water and disperse them, then heat them in a boiling water bath to obtain a gelatinized starch solution.

6. The preparation method according to claim 5, wherein After mixing and dispersing starch with water, the concentration of the starch is g / mL.

7. The preparation method according to claim 1, wherein After mixing the polyphenol solution and the gelatinized starch solution, the mass ratio of polyphenol in the polyphenol solution to gelatinized starch in the gelatinized starch solution is .

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