A method for preparing high resistant starch using quercetin

Abstract

The application discloses a method for preparing high-resistant starch by using quercetin; and comprises the following steps: removing total fat of starch: total fat in starch is extracted by using an organic solvent, i.e., n-propanol, in a high-temperature environment; after the extraction is completed, centrifugation is carried out, the obtained starch sample is washed with alcohol, dried, and finally collected and stored; the total-fat-removed starch is mixed with deionized water to configure a suspension with a certain concentration, mixed with quercetin with a certain proportion, subjected to ultrasonic treatment, then heated at high temperature and continuously stirred, and finally subjected to freeze-drying, grinding and sieving to obtain resistant starch. According to the application, the total fat is removed and the starch is subjected to ultrasonic treatment, so that more sites combined with quercetin are reserved, more quercetin-amylase complexes are formed, starch digestion is inhibited, high-resistant starch is prepared, and the development of low-GI healthy food is facilitated.

Description

Technical Field

[0001] This invention relates to the field of food technology, and more specifically, to a method for preparing highly resistant starch using quercetin. Background Technology

[0002] Starch, as an important renewable natural substance, is one of the main sources of carbohydrates in the human diet. Starch has many advantages, such as low cost and wide availability, and is widely used in the food industry. Many starch-based foods are also popular with consumers, such as rice and noodle products, as well as seasonings used for thickening sauces in daily meals. Based on the rate at which digestive enzymes hydrolyze starch to release glucose, starch is classified into rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). Rapidly digestible starch can cause a rapid rise in blood sugar levels after ingestion, which is detrimental to health. Slowly digestible starch helps maintain stable blood sugar levels, thus being more beneficial to health. Resistant starch is not digested and absorbed by the human body, but it can be fermented and utilized by microorganisms in the colon to produce natural short-chain fatty acids. This process not only helps maintain stable blood sugar levels but also lowers cholesterol levels and reduces the risk of stomach ulcers, colitis, and colon cancer. Therefore, resistant starch is considered a beneficial nutrient, offering potential benefits for promoting overall health.

[0003] With increasing public awareness of healthy eating, resistant starch has become a highly sought-after food ingredient, especially among consumers who need to control their blood sugar and weight, such as diabetics. Common methods for preparing resistant starch include starch source screening, cooking and cooling, and fermentation. However, existing methods may affect the taste and texture of food, reducing its overall palatability. Furthermore, the preparation process of resistant starch can be relatively complex, increasing production costs and posing a challenge to large-scale application. Therefore, finding simpler, more economical methods to prepare resistant starch while maintaining food quality to promote its widespread application in the food industry is a current research hotspot. Many natural substances, such as carbohydrates, amino acids, and flavonoids, are often used to improve the properties of starch. Plant flavonoids, as important bioactive substances, possess various biological activities such as antioxidant, anti-inflammatory, and anticancer properties, which are beneficial to human health and have been widely studied and applied in the food, biological, pharmaceutical, and chemical industries. Quercetin is a flavonoid compound naturally found in many plants. It possesses various pharmacological effects, including antioxidant, anti-inflammatory, anti-cancer, blood pressure-lowering, and blood sugar-lowering properties. It also acts as a natural preservative, enhancing food color, improving food quality, and extending shelf life. Furthermore, ultrasonic treatment, as a physical modification technique, has significant effects and advantages in modifying starch. Its high-frequency vibration can disrupt the starch molecular structure, adjust particle size, improve rheological properties, enhance hydrolysis reactions, and improve starch functionality. The advantages of ultrasonic treatment include high energy efficiency, fast reaction speed, good controllability, no calorific effect, and wide applicability. This makes ultrasonic treatment a green and efficient modification process in the food industry, providing new possibilities for the application of starch in food processing.

[0004] Numerous studies have shown that plant flavonoids can, to some extent, alter the conformation of starch molecules and inhibit the activity of digestive enzymes such as α-amylase, thereby inhibiting starch digestion. The effects of flavonoids such as quercetin on the preparation of resistant starch have been reported. For example, patent CN 107522790 A discloses a novel modified starch with both anti-digestion and antioxidant activities prepared from native starch through sequential carboxymethylation modification and quercetin covalent modification. Patent CN 104984346 A discloses that flavonoids such as quercetin can be used as α-glucosidase activity inhibitors. Patent CN 101831087 A discloses a method for preparing resistant starch, which uses starch as a raw material and adds an appropriate amount of quercetin during gelatinization to form a highly dispersed quercetin-starch complex, i.e., resistant starch. However, this preparation method requires strict reaction conditions and equipment (reflux condenser and constant pressure dropping funnel), making it difficult to implement industrially. Furthermore, the addition of ethanol during gelatinization heating may result in chemical residues, posing a food safety risk. Currently, there are no reports on removing total lipid molecules from starch itself to increase the binding sites between starch and quercetin. Moreover, with the assistance of ultrasonic treatment, the mechanical and thermal effects of ultrasound can lead to the breakage and dispersion of starch granules, increasing the surface area of ​​starch, which helps improve starch solubility and stability, enhances the interaction between starch molecules and quercetin, and thus prepares highly resistant starch. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing highly resistant starch using quercetin. This invention is the first to propose the removal of total starch lipids. Total starch lipids are divided into internal lipids and surface lipids, existing on the surface and inside the granules of natural starch. Internal lipids mostly exist in the form of amylose inclusion complexes, while surface lipids are usually in a free state or bound to the hydroxyl groups of starch molecules through ionic or hydrogen bonds. Removing total starch lipids exposes more amylose helical cavities within the starch. Ultrasonic treatment creates cavitation in a short time, generating high temperature and pressure, promoting the release of amylose during starch gelatinization and enhancing its interaction with quercetin at high temperatures. Based on this, after removing total starch lipids, modifying starch with quercetin under ultrasonic assistance promotes the entry of more hydrophobic quercetin into the amylose helical cavities, forming an amylose-quercetin complex. The present invention aims to significantly alter the conformation of starch molecules, hinder the binding of starch to digestive enzymes, and increase the encapsulation rate of quercetin to inhibit the activity of digestive enzymes, thereby ultimately achieving the goal of preparing highly resistant starch.

[0006] The objective of this invention is achieved through the following approach:

[0007] This invention provides a method for preparing high-resistant starch using quercetin. The method includes: adding quercetin to defatted starch (suspension), subjecting it to ultrasonic treatment, high-temperature heating treatment, and freeze-drying to obtain high-resistant starch.

[0008] In one embodiment of the present invention, the starch is ordinary starch containing amylose.

[0009] As one embodiment of the present invention, the organic extractant used for total fat removal is a mixed solvent of water and n-propanol with a volume ratio of 1:2 to 1:3.

[0010] As one embodiment of the present invention, the total fat removal extraction environment is 90-100℃, and the extraction time is 2-3h.

[0011] In one embodiment of the present invention, in the process of defatting, the ratio of starch to organic extractant is 1:5 to 1:10 (w / v).

[0012] As one embodiment of the present invention, the total fat content of the defatted starch suspension is 10-20% by mass.

[0013] In some implementation examples, the preparation of the defatted starch includes the following steps: extracting lipids from starch using an organic extractant at high temperature; centrifuging after extraction, and washing and drying the obtained starch sample with alcohol.

[0014] In one embodiment of the present invention, the alcohol washing is the washing of starch with anhydrous ethanol.

[0015] As one embodiment of the present invention, the amount of quercetin added is 4-5% (w / w) of the weight of defatted starch.

[0016] As one embodiment of the present invention, the ultrasonic treatment is performed by heating and stirring at 70-80°C with an ultrasonic power of 400-450W for 20 minutes.

[0017] As one embodiment of the present invention, the high-temperature heating treatment is heating and stirring at 90-100°C for 1-1.5 hours.

[0018] As one embodiment of the present invention, the freeze-drying conditions are a temperature of -50 to -40°C and a time of 40-50 hours.

[0019] In one embodiment of the present invention, the freeze-drying process further includes grinding and sieving steps. The grinding is performed using a universal grinding mill. The sieving is performed using an 80-100 mesh sieve.

[0020] The highly resistant starch prepared by the above method also falls within the scope of protection of this invention.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) This invention uses starch as a substrate and employs quercetin to form a complex with starch, thereby altering the conformation of starch molecules and inhibiting the activity of digestive enzymes during digestion to prepare resistant starch.

[0023] (2) The present invention uses a method of extracting total starch lipids with high temperature organic reagents. Removing total starch lipids can expose more amylose helical cavities, allowing more quercetin monomers with hydrophobic groups to enter the amylose helical cavities, forming more V-shaped amylose-quercetin complexes and enhancing the resistance of starch.

[0024] (3) This invention uses ultrasonic treatment to form cavitation in a short time, generating high heat and high pressure, which promotes the release of amylose during starch gelatinization and strengthens its interaction with quercetin at high temperature, inhibiting starch digestion and preparing high resistant starch, which is helpful for the development of low GI health foods. Attached Figure Description

[0025] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0026] Figure 1 This invention provides a method for rapidly digesting starch content in an embodiment of the present invention.

[0027] Figure 2 The content of resistant starch is shown in the embodiments of the present invention.

[0028] Figure 3 This invention provides a comparative example of rapid digestion of starch content.

[0029] Figure 4 The content of resistant starch in the comparative example of this invention is shown. Detailed Implementation

[0030] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0031] The samples obtained in Examples 1-4 and Comparative Examples 1-10 were subjected to a starch digestibility test. 550 mg (dry basis) of the sample was boiled in a test tube with 10 mL of distilled water for 20 min. Then, 10 mL of sodium acetate buffer (0.5 M), 50 mg of guar gum, and 15 glass beads were added to the test tube. Next, a mixed enzyme solution was prepared consisting of the supernatant (4.5 g of pancreatic enzyme from porcine pancreas dissolved in 30 mL of distilled water) and 3.9 mL of amylase. The mixed enzyme solution (5 mL) was added to each sample tube, and the test tubes were shaken in a 37°C water bath. After 20 min and 120 min, 0.5 mL of the hydrolysate was mixed with 20 mL of 80% ethanol to terminate the reaction. The amount of glucose released was determined using a GOPOD assay kit. Glucose content was determined colorimetrically at a wavelength of 510 nm. The proportions of RDS, SDS, and RS in the mixture were calculated using the Englyst method: %RDS = %SD20, %SDS = %SD120 - %SD20, %RS = 100% - (%RDS + %SDS). %SD20 refers to the proportion of starch digested in 20 min, and %SD120 refers to the proportion of starch digested in 120 min. The results are as follows: Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown.

[0032] Example 1

[0033] This embodiment relates to a method for preparing highly resistant starch using quercetin, the steps of which are as follows:

[0034] Step 1: Prepare a lipid extraction reagent by mixing the organic solvent n-propanol and water at a volume ratio of 3:1.

[0035] Step 2: Remove total starch lipids. Prepare a starch suspension by mixing ordinary corn starch with lipid extraction reagent at a material-to-liquid ratio of 1:10 (w / v). Extract at 95℃ with magnetic stirring for 2 hours. After extraction, centrifuge (3000 x g, 15 min). Wash the obtained starch sample with alcohol, air dry, and finally collect and store the starch.

[0036] Step 3: Mix defatted starch with deionized water to prepare a 10% (w / w) defatted starch suspension. Mix the suspension with a certain proportion of quercetin and vortex. The amount of quercetin added is 5% (w / w) of the starch weight to obtain a quercetin and defatted starch premix. Place the premix in an ultrasonic processor, set the ultrasonic power to 400W, heat at 70℃ and stir for 20 minutes to obtain a quercetin and defatted starch mixture.

[0037] Step 4: Heat the quercetin and defatted starch mixture from Step 3 at 90°C with continuous stirring for 1.5 hours to obtain the quercetin and defatted starch complex. Freeze-dry the complex at -45°C for 45 hours. Grind the complex and pass it through a 100-mesh sieve to obtain the sample.

[0038] Results: The ordinary starch prepared in this experiment contained 64.64% rapidly digestible starch and 30.85% resistant starch. In comparison, the ordinary starch without quercetin contained 95.98% rapidly digestible starch and 2.11% resistant starch (Comparative Example 1); the ordinary starch with quercetin contained 86.37% rapidly digestible starch and 10.73% resistant starch (Comparative Example 2); and the defatted ordinary starch without quercetin contained 86.68% rapidly digestible starch and 10.01% resistant starch (Comparative Example 3). The defatted ordinary starch with quercetin contained... The readily digestible starch content in defatted regular starch was 74.66% and the resistant starch content was 18.45% (Comparative Example 4). The readily digestible starch content in regular starch without quercetin after ultrasonic treatment was 94.69% and the resistant starch content was 2.66% (Comparative Example 5). The readily digestible starch content in regular starch with quercetin after ultrasonic treatment was 80.93% and the resistant starch content was 15.69% (Comparative Example 6). The readily digestible starch content in defatted regular starch without quercetin after ultrasonic treatment was 85.58% and the resistant starch content was 3.93% (Comparative Example 7). The readily digestible starch content in defatted waxy starch with quercetin after ultrasonic treatment was 91.31% and the resistant starch content was 2.36% (Comparative Example 8). The readily digestible starch content in regular starch with only surface fat removed, ultrasonic treatment, and quercetin added was 85.92% and the resistant starch content was 9.63% (Comparative Example 9). In this embodiment, the rapidly digestible starch content is significantly reduced, while the resistant starch content is significantly increased.

[0039] Example 2

[0040] This embodiment relates to a method for preparing highly resistant starch using quercetin. The method is the same as in Example 1, except that:

[0041] In step 2, the magnetic stirring temperature is 90℃.

[0042] Implementation results: such as Figure 1 and 2 As shown, the ordinary starch prepared in this embodiment contains 64.62% rapidly digestible starch and 30.60% resistant starch, which is not significantly different from that in Example 1.

[0043] Example 3

[0044] This embodiment relates to a method for preparing highly resistant starch using quercetin. The method is the same as in Example 1, except that:

[0045] In step 2, the magnetic stirring temperature is 100℃.

[0046] Implementation results: such as Figure 1 and 2 As shown, the ordinary starch prepared in this embodiment contains 64.31% rapidly digestible starch and 30.82% resistant starch, which is not significantly different from that in Example 1.

[0047] Example 4

[0048] This embodiment relates to a method for preparing highly resistant starch using quercetin. The method is the same as in Example 1, except that:

[0049] In step 4, the ultrasonic power is set to 450W, and the mixture is heated and stirred at 80℃ for 20 minutes.

[0050] Implementation results: such as Figure 1 and 2 As shown, the ordinary starch prepared in this embodiment has a rapidly digestible starch content of 63.96% and a resistant starch content of 30.90%, which is not significantly different from that in Example 1.

[0051] Comparative Example 1

[0052] This comparative example relates to a method for preparing highly resistant starch, the steps of which are as follows:

[0053] Step 1: Mix ordinary corn starch with deionized water to prepare a 10% (w / w) starch suspension, and heat it at 70°C while stirring continuously for 20 minutes.

[0054] Step 2: Heat the starch from Step 1 at 90℃ with continuous stirring for 1.5 hours. Freeze-dry at -45℃ for 45 hours, grind, and pass through a 100-mesh sieve to obtain the sample.

[0055] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 95.98%, and the resistant starch content is 2.11%. The rapidly digestible starch content of this comparative example is much higher than that of Example 1, and the resistant starch content of this comparative example is much lower than that of Example 1. This indicates that the natural starch without added quercetin has a fast digestion rate and a low resistant starch content.

[0056] Comparative Example 2

[0057] This comparative example relates to a method for preparing highly resistant starch using quercetin, the steps of which are as follows:

[0058] Step 1: Mix ordinary corn starch with deionized water to prepare a 10% (w / w) starch suspension. Mix the suspension with a certain proportion of quercetin and vortex. The amount of quercetin added is 5% (w / w) of the starch weight. Heat at 70°C and stir continuously for 20 minutes to obtain a mixture of quercetin and starch.

[0059] Step 2: The quercetin and starch mixture from Step 1 is heated at 90℃ and stirred continuously for 1.5 hours to obtain a quercetin-starch complex. It is then freeze-dried at -45℃ for 45 hours, ground, and passed through a 100-mesh sieve to obtain the sample.

[0060] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 86.37%, and the resistant starch content is 10.73%. The rapidly digestible starch content of this comparative example is much higher than that of Example 1, and the resistant starch content is much higher than that of Comparative Example 1, but lower than that of Example 1. This indicates that quercetin can reduce the digestion rate of starch, but the effect is very limited, and the resistant starch content in the obtained starch is low.

[0061] Comparative Example 3

[0062] This comparative example relates to a method for preparing highly resistant starch, the steps of which are as follows:

[0063] Step 1: Prepare a lipid extraction reagent by mixing the organic solvent n-propanol and water at a volume ratio of 3:1.

[0064] Step 2: Remove total starch lipids. Prepare a starch suspension by mixing ordinary corn starch with lipid extraction reagent at a material-to-liquid ratio of 1:10 (w / v). Extract at 95℃ with magnetic stirring for 2 hours. After extraction, centrifuge (3000 x g, 15 min). Wash the obtained starch sample with alcohol, air dry, and finally collect and store the starch.

[0065] Step 3: Mix the defatted starch collected in Step 2 with deionized water to prepare a 10% (w / w) starch suspension, and heat it at 70°C while stirring continuously for 20 min.

[0066] Step 4: Heat the defatted starch from Step 3 at 90℃ with continuous stirring for 1.5 hours. Freeze-dry at -45℃ for 45 hours, grind, and pass through a 100-mesh sieve to obtain the sample.

[0067] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 86.68%, and the resistant starch content is 10.01%. The rapidly digestible starch content of this comparative example is much higher than that of Example 1, while the resistant starch content is much lower than that of Example 1. This indicates that removing lipids from starch can inhibit starch digestion to a certain extent, but the resistant starch content is still low.

[0068] Comparative Example 4

[0069] This comparative example relates to a method for preparing highly resistant starch using quercetin, the steps of which are as follows:

[0070] Step 1: Prepare a lipid extraction reagent by mixing the organic solvent n-propanol and water at a volume ratio of 3:1.

[0071] Step 2: Remove total starch lipids. Prepare a starch suspension by mixing ordinary corn starch with lipid extraction reagent at a material-to-liquid ratio of 1:10 (w / v). Extract at 95℃ with magnetic stirring for 2 hours. After extraction, centrifuge (3000 x g, 15 min). Wash the obtained starch sample with alcohol, air dry, and finally collect and store the starch.

[0072] Step 3: Mix the defatted starch collected in Step 2 with deionized water to prepare a 10% (w / w) starch suspension. Mix the suspension with a certain proportion of quercetin and vortex. The amount of quercetin added is 5% (w / w) of the starch weight. Heat at 70°C and stir continuously for 20 minutes to obtain a mixture of quercetin and defatted starch.

[0073] Step 4: Heat the mixture of quercetin and defatted starch from Step 3 at 90°C with continuous stirring for 1.5 hours to obtain the quercetin-defatted starch complex. Freeze-dry at -45°C for 45 hours, grind, and pass through a 100-mesh sieve to obtain the sample.

[0074] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 74.66%, and the resistant starch content is 18.45%. The rapidly digestible starch content of this comparative example is much higher than that of Example 1, and the resistant starch content is much higher than that of Comparative Example 1, but lower than that of Example 1. This indicates that removing starch lipids can enhance the inhibitory effect of quercetin on starch digestion and increase the resistant starch content, but the resistant starch content is much lower than that of Example 1.

[0075] Comparative Example 5

[0076] This comparative example relates to a method for preparing highly resistant starch, the steps of which are as follows:

[0077] Step 1: Mix ordinary corn starch with deionized water to prepare a 10% (w / w) starch suspension. Place the suspension in an ultrasonic processor, set the ultrasonic power to 400W, heat at 70°C and stir for 20 minutes to obtain a mixture of quercetin and starch.

[0078] Step 2: Heat the starch from Step 1 at 90℃ with continuous stirring for 1.5 hours. Freeze-dry at -45℃ for 45 hours, grind, and pass through a 100-mesh sieve to obtain the sample.

[0079] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 94.69%, and the resistant starch content is 2.66%. The rapidly digestible starch content of this comparative example is much higher than that of Example 1, and the resistant starch content is much lower than that of Example 1. This indicates that ultrasonic treatment alone has a relatively small effect on inhibiting starch digestion.

[0080] Comparative Example 6

[0081] This comparative example relates to a method for preparing highly resistant starch using quercetin, the steps of which are as follows:

[0082] Step 1: Mix ordinary corn starch with deionized water to prepare a 10% (w / w) starch suspension. Mix the suspension with a certain proportion of quercetin and vortex. The amount of quercetin added is 5% (w / w) of the starch weight. Place the suspension in an ultrasonic processor, set the ultrasonic power to 400W, heat at 70℃ and stir for 20 minutes to obtain a mixture of quercetin and starch.

[0083] Step 2: The quercetin and starch mixture from Step 1 is heated at 90℃ and stirred continuously for 1.5 hours to obtain a quercetin-starch complex. It is then freeze-dried at -45℃ for 45 hours, ground, and passed through a 100-mesh sieve to obtain the sample.

[0084] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 80.93%, and the resistant starch content is 15.69%. The rapidly digestible starch content of this comparative example is much higher than that of Example 1, and the resistant starch content is much lower than that of Example 1, but higher than that of Comparative Example 1. This indicates that ultrasonic treatment can enhance the inhibitory effect of quercetin on starch digestion to a certain extent, but the effect is not ideal, and the resistant starch content is still low.

[0085] Comparative Example 7

[0086] This comparative example relates to a method for preparing highly resistant starch, the steps of which are as follows:

[0087] Step 1: Prepare a lipid extraction reagent by mixing the organic solvent n-propanol and water at a volume ratio of 3:1.

[0088] Step 2: Remove total starch lipids. Prepare a starch suspension by mixing ordinary corn starch with lipid extraction reagent at a material-to-liquid ratio of 1:10 (w / v). Extract at 95℃ with magnetic stirring for 2 hours. After extraction, centrifuge (3000 x g, 15 min). Wash the obtained starch sample with alcohol, air dry, and finally collect and store the starch.

[0089] Step 3: Mix the defatted starch collected in Step 2 with deionized water to prepare a 10% (w / w) starch suspension. Place the suspension in an ultrasonic processor, set the ultrasonic power to 400W, heat at 70°C and stir for 20 minutes.

[0090] Step 4: Heat the defatted starch from Step 3 at 90℃ with continuous stirring for 1.5 hours. Freeze-dry at -45℃ for 45 hours, grind, and pass through a 100-mesh sieve to obtain the sample.

[0091] Implementation results: Figure 3 and Figure 4 It can be seen that the rapid digestible starch content of this comparative example is 85.58%, and the resistant starch content is 3.93%. The rapid digestible starch content of this comparative example is much higher than that of Example 1, and the resistant starch content is much lower than that of Example 1, indicating that the removal of starch fat and ultrasonic treatment have little inhibitory effect on starch digestion.

[0092] Comparative Example 8

[0093] Step 1: Prepare a lipid extraction reagent by mixing the organic solvent n-propanol and water at a volume ratio of 3:1.

[0094] Step 2: Remove total starch lipids. Prepare a starch suspension by mixing waxy corn starch and lipid extraction reagent at a ratio of 1:10 (w / v). Extract at 95℃ with magnetic stirring for 2 hours. After extraction, centrifuge (3000 x g, 15 min). Wash the obtained starch sample with alcohol, air dry, and finally collect and store the starch.

[0095] Step 3: Mix the defatted starch collected in Step 2 with deionized water to prepare a 10% (w / w) defatted starch suspension. Mix the suspension with a certain proportion of quercetin and vortex. The amount of quercetin added is 5% (w / w) of the starch weight to obtain a quercetin and defatted starch premix. Place the premix in an ultrasonic processor, set the ultrasonic power to 400W, heat at 70℃ and stir for 20 minutes to obtain a quercetin and defatted starch mixture.

[0096] Step 4: The mixture of quercetin and defatted starch from Step 3 is heated at 90°C and stirred continuously for 1.5 hours to obtain a quercetin-defatted starch complex. The complex is then freeze-dried, ground, and sieved to obtain the sample.

[0097] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 91.31%, and the resistant starch content is 2.36%. The rapidly digestible starch content of this comparative example is much higher than that of Example 1, and the resistant starch content is much lower than that of Example 1. This indicates that quercetin mainly prepares resistant starch by forming a complex with amylose, and cannot play a role in waxy starch without amylose, resulting in a lower resistant starch content in the obtained starch.

[0098] Comparative Example 9

[0099] This comparative example relates to a method for preparing highly resistant starch using quercetin, the steps of which are as follows:

[0100] Step 1: Prepare a lipid extraction reagent by mixing the organic solvent n-propanol and water at a volume ratio of 3:1.

[0101] Step 2: Remove surface lipids from starch. Prepare a starch suspension by mixing ordinary corn starch with lipid extraction reagent at a material-to-liquid ratio of 1:10 (w / v) and continuously stir at room temperature for 2 hours. After extraction, centrifuge (3000 x g, 15 min). Wash the obtained starch sample with alcohol, air dry, and finally collect and store the starch.

[0102] Step 3: Mix the defatting starch collected in Step 2 with deionized water to prepare a 10% (w / w) defatting starch suspension. Mix the suspension with a certain proportion of quercetin and vortex. The amount of quercetin added is 5% (w / w) of the starch weight. Place the suspension in an ultrasonic processor, set the ultrasonic power to 400W, heat at 70℃ and stir for 20 minutes to obtain a mixture of quercetin and defatting starch.

[0103] Step 4: Heat the mixture of quercetin and defatting starch from Step 3 at 90°C with continuous stirring for 1.5 hours to obtain the quercetin-defatting starch complex. Freeze-dry at -45°C for 45 hours, grind, and pass through a 100-mesh sieve to obtain the sample.

[0104] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 85.92%, and the resistant starch content is 9.63%. The rapidly digestible starch content of this comparative example is much higher than that of Example 1, and the resistant starch content is much lower than that of Example 1. This indicates that simply removing surface lipids cannot sufficiently enhance the binding of quercetin to starch, resulting in a lower resistant starch content in the obtained starch.

[0105] Comparative Example 10

[0106] This comparative example relates to a method for preparing highly resistant starch using quercetin, the steps of which are as follows:

[0107] Step 1: Prepare the extraction reagent by mixing the organic solvent ethanol and water at a volume ratio of 3:1.

[0108] Step 2: Prepare a starch suspension by mixing ordinary corn starch with extraction reagent at a ratio of 1:10 (w / v), and extract with magnetic stirring at 95℃ for 2 hours. After extraction, centrifuge (3000 x g, 15 min), wash the obtained starch sample with alcohol, air dry, and finally collect and store the starch.

[0109] Step 3: Mix the defatted starch collected in Step 2 with deionized water to prepare a 10% (w / w) defatted starch suspension. Mix the suspension with a certain proportion of quercetin and vortex. The amount of quercetin added is 5% (w / w) of the starch weight. Place the suspension in an ultrasonic processor, set the ultrasonic power to 400W, heat at 70℃ and stir for 20 minutes to obtain a mixture of quercetin and defatted starch.

[0110] Step 4: Heat the quercetin and defatted starch mixture from Step 3 at 90°C with continuous stirring for 1.5 hours to obtain the quercetin and defatted starch complex. Freeze-dry the complex at -45°C for 45 hours. Grind the complex and pass it through a 100-mesh sieve to obtain the sample.

[0111] Implementation results: Figure 3 and Figure 4 It can be seen that the rapidly digestible starch content of this comparative example is 76.42%, and the resistant starch content is 20.29%. The rapidly digestible starch content of the comparative example is much higher than that of Example 1, and the resistant starch content is much lower than that of Example 1. This indicates that ethanol pretreatment of starch does not enhance the binding of quercetin to starch, and the resulting starch has a low resistant starch content.

[0112] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for preparing highly resistant starch using quercetin, characterized in that, The method includes: adding quercetin to defatted starch, subjecting it to ultrasonic treatment, high-temperature heating treatment, and freeze-drying to obtain high-resistant starch; The starch is ordinary starch containing amylose, and the amount of quercetin added is 4-5% w / w of the total fattened starch. The ultrasonic treatment is performed by heating and stirring at 70-80 ℃ for 20 min with an ultrasonic power of 400-450 W; the high-temperature heating treatment is performed by heating and stirring at 90-100 ℃ for 1-1.5 h. The organic extractant used for total fat removal is a mixed solvent of water and n-propanol with a volume ratio of 1:2 to 1:

3. The total fat removal process is carried out at 90-100℃ for 2-3 hours.

2. The preparation method according to claim 1, characterized in that, In the process of defatting total fat, the ratio of starch to organic extractant in liquid is 1:5-1:10 w / v.

3. The preparation method according to claim 1, characterized in that, The freeze-drying conditions are a temperature of -50 to -40°C and a time of 40 to 50 hours.

4. A highly resistant starch prepared by the method according to any one of claims 1-3.

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