A starch-lipid complex and a method of preparation

Abstract

The application discloses a starch-lipid complex and a preparation method thereof, and relates to the field of modified starches. The preparation method comprises the following steps: homogenizing an ethanol solution and starch to prepare starch milk, stirring and adjusting the pH to 10-11, then adjusting to neutral to obtain treated starch milk, ultrasonic treatment, centrifugation and water washing to obtain treated starch; homogenizing the treated starch with water to prepare a suspension, stirring after adding lipids under the condition of a temperature of 80-100 DEG C, cooling and recrystallization to prepare the starch-lipid complex. The starch molecules are dispiraled into single helix structure by the ethanol and alkali liquor cooperated ultrasonic treatment, and a V-shaped hydrophobic helical cavity structure is formed, so that more binding sites are provided for the lipid molecules. Compared with the starch-lipid complex prepared by the traditional hydrothermal treatment method, the starch-lipid complex has higher complex index and anti-digestibility, and when added into food, the starch-lipid complex can provide satiety while reducing the blood glucose index, so the starch-lipid complex has good application prospect.

Description

Technical Field

[0001] This invention relates to the field of modified starch, and more particularly to a starch-lipid complex and its preparation method. Background Technology

[0002] Starch, as a major carbohydrate in staple foods, plays an irreplaceable role as a primary source of energy for human metabolism. However, starch is also a major glycemic carbohydrate; the degree and speed of its digestion are risk factors for many diet-related metabolic chronic diseases. Excessive intake and long-term consumption of foods containing rapidly digestible starch can lead to a rapid rise in blood sugar levels, easily causing insulin response disorders. In recent years, due to increased food diversity and an unbalanced diet, the imbalance between energy intake and expenditure has led to a year-on-year increase in the number of people suffering from insulin resistance, diabetes, obesity, and other related metabolic syndromes. Studies have shown that Englyst et al. classified starch into three types based on in vitro simulated digestion and bioavailability: rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). Among these, foods with certain digestible properties (containing a certain amount of SDS and RS) can sustainably and slowly release energy, maintain postprandial blood glucose levels, improve the body's sensitivity to insulin, and promote gut health, which is crucial for human health. Therefore, how to regulate the rate and extent of starch digestion in the human digestive tract and reduce starch digestibility to meet people's pursuit of health has become a key scientific problem that the staple food industry urgently needs to solve in the context of the great health trend.

[0003] In recent years, research on starch-lipid complexes has become a hot topic. Starch-lipid complexes belong to RS5 type resistant starch, and their crystal structure mainly exhibits a "V" shape, which is also a marker for the formation of starch-lipid complexes in the system. Starch-lipid complexes increase the content of resistant starch to a certain extent while reducing the content of rapidly digestible starch, and have health benefits similar to dietary fiber, such as controlling blood sugar, improving gut microbiota, and increasing the nutritional value of food.

[0004] Traditional techniques typically employ hydrothermal treatment to prepare starch-lipid complexes. These complexes utilize hydrophobic interactions and hydrogen bonds between lipids and starch to form inclusion complexes, preventing direct contact between starch and amylase, thus delaying starch digestion and achieving resistance to digestion. However, the effects of traditional hydrothermal treatment on starch-lipid complexes are limited, exhibiting low integration rates and insignificant resistance. Therefore, based on the current research status and limitations of starch-lipid complexes, further improvements to the processing technology are needed to significantly enhance starch resistance to digestion. Summary of the Invention

[0005] This invention provides a starch-lipid complex and its preparation method, which uses ethanol and alkali synergistic ultrasonic treatment to promote the compounding of starch and lipids and improve the digestibility of the complex.

[0006] To address the aforementioned technical problems, one objective of this invention is to provide a method for preparing a starch-lipid complex, comprising the following steps:

[0007] (1) Prepare starch milk by homogenizing ethanol solution and starch, stirring and adding alkaline solution to adjust pH to 10-11, and after stirring the reaction is complete, add acid solution to adjust to neutral to obtain processed starch milk;

[0008] (2) The processed starch milk is subjected to ultrasonic treatment, centrifugation, and water washing to obtain processed starch;

[0009] (3) Mix water and the treated starch to prepare a suspension. Add lipids and stir to combine at a temperature of 80-100℃. Then cool and recrystallize. After centrifugation, washing with alcohol and drying, obtain starch-lipid complex.

[0010] This application employs ethanol and alkali to treat starch. The -OH groups in the alkali interact with the -OH groups on the glucose residues of starch, giving the particles a negative charge. The mutual repulsion between starch molecules promotes the swelling of starch particles, causing the double helix structure of starch to unwind into a single helix structure. Through hydrogen bonding between ethanol and starch molecules, excessive swelling of starch particles is inhibited, inducing the formation of a V-shaped hydrophobic helical cavity structure. This crystal structure is conducive to the migration and dispersion of lipid molecules, thus providing possibilities for diffusion, adsorption, and interaction between starch particles and lipid molecules. Subsequently, ultrasonic treatment is used to promote the expansion of the hydrophobic helical cavity of starch through cavitation effect and mechanical action, physically modifying the multi-level structure of starch particles and breaking and reorganizing molecular chains. The cavitation effect can induce the formation of micropores or cracks on the surface of starch particles, while the mechanical shear force can cause the starch molecular chains to break and the double helix structure to depolymerize, making the expansion of the hydrophobic cavity structure inside the starch more easily exposed, providing more binding sites for lipid molecules, and enabling starch and lipids to fully complex. Low-temperature cooling technology is used to further promote the formation of V-shaped starch-lipid complexes. This starch-lipid complex has a high complexation index and strong resistance to digestion.

[0011] As a preferred embodiment, in step (1), the starch is prepared by alkali extraction.

[0012] As a preferred embodiment, in step (1), the starch includes at least one of rice starch, corn starch, tapioca starch, glutinous rice starch, and potato starch.

[0013] As a preferred embodiment, in step (1), the method for preparing the starch includes the following steps:

[0014] After crushing the starch raw material to a particle size greater than 80 mesh, add a 0.1-0.3 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:(2-4). Stir for 1-3 hours, adjust the pH to neutral with an acid solution, centrifuge, wash with water, and then add ethanol to the precipitate at a solid-liquid mass ratio of 1:(1-2). Stir for 1-2 hours, centrifuge, wash with water, dry, and sieve to obtain starch.

[0015] As a preferred embodiment, in the method for preparing starch, the starch raw material is indica rice.

[0016] As a preferred embodiment, the indica rice contains 78.23 wt% total starch, 8.3 wt% protein, 0.54 wt% fat, 10.63 wt% moisture, and 0.51 wt% ash, and the indica rice contains 16.78 wt% amylose.

[0017] As a preferred embodiment, in the starch preparation method, the washing process involves adding water for washing, centrifuging at a rate of 3000-6000 r / min, and repeating the washing process 2-5 times.

[0018] As a preferred embodiment, in the starch preparation method, the centrifugation rate is 3000-8000 r / min.

[0019] As a preferred embodiment, in the starch preparation method, the drying temperature is 40-50℃ and the drying time is 10-15h.

[0020] As a preferred embodiment, in step (1), the concentration of ethanol in the ethanol solution is 60wt%-80wt%.

[0021] As a preferred embodiment, in step (1), the starch concentration in the starch milk is 0.05-0.5 g / mL.

[0022] As a preferred option, in step (1), the stirring reaction temperature is 25-45℃.

[0023] As a preferred option, in step (1), the stirring reaction time is 20-60 min.

[0024] As a preferred embodiment, in step (1), the stirring rate is 200-400 rpm.

[0025] As a preferred embodiment, in step (1), the alkali in the alkaline solution is at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, and potassium hydroxide, and the concentration of the alkali in the alkaline solution is 0.1-5 mol / L.

[0026] As a preferred embodiment, in step (1), the acid in the acid solution is at least one of hydrochloric acid, phosphoric acid, sulfuric acid, and acetic acid, and the concentration of the acid solution is 0.1-0.5 mol / L.

[0027] As a preferred option, in step (2), the ultrasonic power is 250-350W and the ultrasonic time is 15-30min.

[0028] As a preferred embodiment, in step (3), the concentration of starch in the suspension is 0.05-0.5 g / mL.

[0029] As a preferred embodiment, in step (3), the lipid is at least one of myristic acid, lauric acid, palmitic acid, stearic acid, oleic acid, and linoleic acid.

[0030] As a preferred embodiment, in step (3), the mass ratio of starch to lipids in the suspension is 1:(8-12).

[0031] As a preferred option, in step (3), the mixing and compounding time is 30-60 min.

[0032] As a preferred option, in step (3), the cooling recrystallization temperature is 3-5℃ and the time is 1-3h.

[0033] As a preferred option, in step (3), the drying is performed by freeze drying at -85 to -75°C for 12-36 hours.

[0034] As a preferred option, in step (3), the mesh size of the sieve is 80-100 mesh.

[0035] As a preferred option, in steps (2) and (3), the centrifugation rate is 3000-8000 r / min.

[0036] As a preferred option, in step (2), the water washing involves adding water for washing and then centrifuging at a rate of 3000-6000 r / min, and repeating the washing 2-5 times.

[0037] As a preferred option, in step (3), the alcohol washing involves adding ethanol for washing and then centrifuging at a rate of 3000-6000 r / min, and repeating the washing 2-5 times.

[0038] To solve the above-mentioned technical problems, the second objective of this invention is to provide a starch-lipid complex prepared by the above-mentioned method.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. This invention uses ethanol and alkali solution to pretreat starch, causing the double helix structure of starch molecules to unwind into a single helix structure, forming a V-shaped hydrophobic helical cavity structure. Subsequently, ultrasonic treatment is used to further expand the hydrophobic helical cavity structure of starch through cavitation effect and mechanical action, providing more binding sites for lipid molecules, so that starch and lipids can fully combine. Low temperature cooling technology is used to promote the formation of V-shaped starch-lipid complex. The prepared starch-lipid complex has a high complexation index and strong resistance to digestion.

[0041] 2. The present invention uses a green and environmentally friendly processing technology to prepare starch-lipid complexes. No toxic chemical reagents are used in the entire preparation process. The reaction process is simple, low-cost and environmentally friendly. The prepared starch-lipid complexes have a high complex index and good digestibility, which has obvious advantages compared with starch-lipid complexes prepared by traditional methods. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the preparation method of a starch-lipid complex in Example 1 of the present invention;

[0043] Figure 2: This is a statistical chart of the composite index of a starch-lipid complex in Example 1 and Comparative Examples 6-11 of the present invention (Note: RS - Comparative Example 1; GRS - Comparative Example 5; RSMA - Comparative Example 6; EA - RSMA - Comparative Example 7; US - RSMA - Comparative Example 8; EA - HH - RSMA - Comparative Example 10; AUS - RSMA - Comparative Example 9; EA - US - RSMA - Comparative Example 11; EA - US - RSMA - Example 1);

[0044] Figure 3 The starch-lipid complex in Example 1 and Comparative Examples 1, 5-11 of this invention was subjected to a temperature of 4000 cm⁻¹. -1 and 1000cm -1 Infrared spectra of absorption characteristic peaks between (Note: RS - Comparative Example 1; GRS - Comparative Example 5; RSMA - Comparative Example 6; EA - RSMA - Comparative Example 7; US - RSMA - Comparative Example 8; EA - HH - RSMA - Comparative Example 10; AUS - RSMA - Comparative Example 9; EA - US - RSMA - Comparative Example 11; EA - US - RSMA - Example 1);

[0045] Figure 4 The starch-lipid complex in Example 1 and Comparative Examples 1, 5-11 of this invention was subjected to a reaction at 1200 cm⁻¹. -1 and 800cm -1 Infrared spectra of absorption characteristic peaks between (Note: RS - Comparative Example 1; GRS - Comparative Example 5; RSMA - Comparative Example 6; EA - RSMA - Comparative Example 7; US - RSMA - Comparative Example 8; EA - HH - RSMA - Comparative Example 10; AUS - RSMA - Comparative Example 9; EA - US - RSMA - Comparative Example 11; EA - US - RSMA - Example 1);

[0046] Figure 5 : Raman spectra of a starch-lipid complex in Example 1 and Comparative Examples 1, 5-11 of the present invention (Note: RS - Comparative Example 1; GRS - Comparative Example 5; RSMA - Comparative Example 6; EA - RSMA - Comparative Example 7; US - RSMA - Comparative Example 8; EA - HH - RSMA - Comparative Example 10; AUS - RSMA - Comparative Example 9; EA - US - RSMA - Comparative Example 11; EA - US - RSMA - Example 1);

[0047] Figure 6 Raman spectra of a starch-lipid complex in Example 1 and Comparative Examples 1, 5-11 of this invention were measured at 480 cm⁻¹. -1Statistical chart of full width at half maximum (FWHM) of nearby characteristic peaks (Note: RS-Comparative Example 1; GRS-Comparative Example 5; RSMA-Comparative Example 6; EA-RSMA-Comparative Example 7; US-RSMA-Comparative Example 8; EA-HH-RSMA-Comparative Example 10; AUS-RSMA-Comparative Example 9; EA-US-RSMA-Comparative Example 11; EA-US-RSMA-Example 1);

[0048] Figure 7 X-ray diffraction patterns of a starch-lipid complex in Example 1 and Comparative Examples 1, 5-11 of the present invention (Note: RS - Comparative Example 1; GRS - Comparative Example 5; RSMA - Comparative Example 6; EA - RSMA - Comparative Example 7; US - RSMA - Comparative Example 8; EA - HH - RSMA - Comparative Example 10; AUS - RSMA - Comparative Example 9; EA - US - RSMA - Comparative Example 11; EA - US - RSMA - Example 1).

[0049] Figure 8 : Statistical charts showing the determination of V-type crystal content of a starch-lipid complex in Example 1 and Comparative Examples 1, 5-11 of the present invention (Note: RS - Comparative Example 1; GRS - Comparative Example 5; RSMA - Comparative Example 6; EA - RSMA - Comparative Example 7; US - RSMA - Comparative Example 8; EA - HH - RSMA - Comparative Example 10; AUS - RSMA - Comparative Example 9; EA - US - RSMA - Comparative Example 11; EA - US - RSMA - Example 1);

[0050] Figure 9 : These are statistical charts showing the determination of RS, SDS and RDS content in rice starch in Comparative Examples 1-4 of the present invention (Note: RS-Comparative Example 1; GRS-Comparative Example 5; RSMA-Comparative Example 6; EA-RSMA-Comparative Example 7; US-RSMA-Comparative Example 8; EA-HH-RSMA-Comparative Example 10; AUS-RSMA-Comparative Example 9; EA-US-RSMA-Comparative Example 11; EA-US-RSMA-Example 1).

[0051] Figure 10 : These are statistical charts showing the determination of RS, SDS and RDS content in a starch-lipid complex in Example 1 and Comparative Examples 1, 5-11 of the present invention (Note: RS-Comparative Example 1; GRS-Comparative Example 5; RSMA-Comparative Example 6; EA-RSMA-Comparative Example 7; US-RSMA-Comparative Example 8; EA-HH-RSMA-Comparative Example 10; AUS-RSMA-Comparative Example 9; EA-US-RSMA-Comparative Example 11; EA-US-RSMA-Example 1). Detailed Implementation

[0052] 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0054] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0055] As used in this article:

[0056] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0057] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0058] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0059] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the following embodiments and comparative examples are all commercially available, and the same raw materials were used in parallel experiments.

[0060] The indica rice used in the following examples and comparative examples is "Quanyou 9028" indica rice containing 78.23 wt% total starch, 8.3 wt% protein, 0.54 wt% fat, 10.63 wt% moisture, and 0.51 wt% ash, and specifically contains 16.78 wt% amylose.

[0061] Example 1

[0062] A method for preparing a starch-lipid complex, such as Figure 1 As shown, it includes the following steps:

[0063] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0064] (2) Add a 70wt% ethanol solution to the rice starch obtained in step (1) and homogenize to prepare a rice starch milk with a concentration of 0.1g / mL. Place it in a magnetic constant temperature water bath and stir. Control the temperature at 40℃ and the speed at 250rpm. During the stirring process, slowly add a 3.0mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:1 to adjust the pH to about 10.6. Continue stirring for 30min. After stirring is completed, add a 0.3mol / L HCl aqueous solution to adjust the pH to neutral to obtain the processed rice starch milk.

[0065] (3) The processed rice starch milk obtained in step (2) was placed in an ultrasonic crusher at room temperature. The ultrasonic power was 300W and the ultrasonic time was 20min. The probe was placed about 5cm below the liquid surface. During the ultrasonic treatment, a low temperature water bath was used to control the reaction temperature and the water in the water bath was changed every 10min. After the ultrasonic treatment, the rice starch milk was centrifuged at 6000r / min for 20min. The supernatant was discarded and then washed with distilled water. The mixture was centrifuged at 4000r / min for 10min. The washing and centrifugation were repeated twice to obtain the processed rice starch.

[0066] (4) Add distilled water to the treated rice starch obtained in step (3) and homogenize to prepare a suspension with a concentration of 0.1 g / mL. Then, add lipids according to the mass ratio of lipids to treated rice starch of 1:10. Myristic acid was selected as the lipid. Stir for 5 min at a speed of 550 rpm and stir at 90°C for 45 min in a water bath. Place the mixed solution at 4°C to cool and recrystallize for 2 h. Centrifuge at 4000 r / min for 20 min. Then wash with anhydrous ethanol to remove unreacted lipids and centrifuge at 4000 r / min for 10 min. Repeat the ethanol washing and centrifugation twice. Then place the precipitate at -80°C for rapid freezing. After complete freezing, freeze dry for 24 h. After drying, pulverize and pass through an 80 mesh sieve to obtain the starch-myristic acid complex. The sample was named EA-US-RSMA.

[0067] Comparative Example 1

[0068] A method for preparing rice starch includes the following steps:

[0069] Rice was pulverized into rice flour with a particle size greater than 80 mesh. It was then soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3 and stirred for 2 hours. The pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution, and the mixture was centrifuged at 4000 rpm for 10 minutes. The supernatant was discarded, and the mixture was washed and centrifuged three times. Anhydrous ethanol was then added at a solid-liquid mass ratio of 1:1, and the mixture was stirred for 1 hour. The mixture was then centrifuged at 4000 rpm for 10 minutes, and the supernatant was discarded. The mixture was washed and centrifuged three times to obtain a white rice starch precipitate. This precipitate was then dried in an oven at 45°C for 12 hours, pulverized, and passed through an 80-mesh sieve to obtain rice starch, which was named RS.

[0070] Comparative Example 2

[0071] A method for preparing rice starch includes the following steps:

[0072] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0073] (2) Add 70wt% ethanol solution to the rice starch obtained in step (1) and homogenize to prepare rice starch milk with a concentration of 0.1g / mL. Place it in a magnetic constant temperature water bath and stir. Control the temperature at 40℃ and the speed at 250rpm. During the stirring process, slowly add 3.0mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:1 to adjust the pH to about 10.6. Continue stirring for 30min. After stirring, add 0.3mol / L HCl aqueous solution to adjust the pH to neutral. Then centrifuge the rice starch milk at 6000r / min for 20min, discard the supernatant, then add distilled water to wash, centrifuge at 4000r / min for 10min, repeat the washing and centrifugation twice to obtain the processed rice starch. The sample is named EA10.

[0074] Comparative Example 3

[0075] A method for preparing rice starch includes the following steps:

[0076] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0077] (2) Add 70wt% ethanol solution to the rice starch obtained in step (1) and homogenize to prepare rice starch milk with a concentration of 0.1g / mL. Place it in a magnetic constant temperature water bath and stir. Control the temperature at 40℃ and the speed at 250rpm. During the stirring process, slowly add 3.0mol / L NaOH aqueous solution at a solid-liquid mass ratio of 2:1 to adjust the pH to about 9.4. Continue stirring for 30min. After stirring, add 0.3mol / L HCl aqueous solution to adjust the pH to neutral. Then centrifuge the rice starch milk at 6000r / min for 20min, discard the supernatant, then add distilled water to wash, centrifuge at 4000r / min for 10min, repeat the washing and centrifugation twice to obtain the processed rice starch. The sample is named EA9.

[0078] Comparative Example 4

[0079] A method for preparing rice starch includes the following steps:

[0080] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0081] (2) Add 70wt% ethanol solution to the rice starch obtained in step (1) and homogenize to prepare rice starch milk with a concentration of 0.1g / mL. Place it in a magnetic constant temperature water bath and stir. Control the temperature at 40℃ and the speed at 250rpm. During the stirring process, slowly add 2.0mol / L NaOH aqueous solution at a solid-liquid mass ratio of 2:1 to adjust the pH to about 8.5. Continue stirring for 30min. After stirring, add 0.3mol / L HCl aqueous solution to adjust the pH to neutral. Then centrifuge the rice starch milk at 6000r / min for 20min, discard the supernatant, then add distilled water to wash, centrifuge at 4000r / min for 10min, repeat the washing and centrifugation twice to obtain the processed rice starch. The sample is named EA8.

[0082] Comparative Example 5

[0083] A method for preparing gelatinized rice starch includes the following steps:

[0084] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0085] (2) Add distilled water to the rice starch obtained in step (1) and homogenize to prepare a suspension with a concentration of 0.1 g / mL. Heat in a water bath at 90°C for 45 min. Then cool the gelatinized system at 4°C for 2 h and recrystallize. Centrifuge at 4000 r / min for 20 min. Then freeze the precipitate at -80°C. After it is completely frozen, freeze dry for 24 h. After drying, pulverize and pass through an 80-mesh sieve to obtain gelatinized rice starch. The sample is named GRS.

[0086] Comparative Example 6

[0087] A method for preparing a starch-lipid complex includes the following steps:

[0088] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0089] (2) Add distilled water to the rice starch obtained in step (1) and homogenize to prepare a suspension with a concentration of 0.1 g / mL. Then, add lipids at a mass ratio of 1:10 to rice starch. The lipid used is myristic acid. Stir for 5 min at a speed of 550 rpm and stir at 90°C for 45 min in a water bath. Cool the mixture at 4°C for 2 h to recrystallize. Centrifuge at 4000 r / min for 20 min. Then wash with anhydrous ethanol to remove unreacted lipids and centrifuge at 4000 r / min for 10 min. Repeat the ethanol washing and centrifugation twice. Then place the precipitate at -80°C for rapid freezing. After complete freezing, freeze dry for 24 h. After drying, pulverize and pass through an 80 mesh sieve to obtain the starch-myristic acid complex. The sample is named RSMA.

[0090] Comparative Example 7

[0091] A method for preparing a starch-lipid complex includes the following steps:

[0092] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0093] (2) Add 70wt% ethanol solution to the rice starch obtained in step (1) and homogenize to prepare rice starch milk with a concentration of 0.1g / mL. Place it in a magnetic constant temperature water bath and stir. Control the temperature at 40℃ and the speed at 250rpm. During the stirring process, slowly add 3.0mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:1 to adjust the pH to about 10.6. Continue stirring for 30min. After stirring, add 0.3mol / L HCl aqueous solution to adjust the pH to neutral. Then centrifuge the rice starch milk at 6000r / min for 20min, discard the supernatant, then add distilled water to wash, centrifuge at 4000r / min for 10min, repeat the washing and centrifugation twice to obtain the processed rice starch.

[0094] (3) Add distilled water to the treated rice starch obtained in step (2) and homogenize to prepare a suspension with a concentration of 0.1 g / mL. Then, add lipids according to the mass ratio of lipids to treated rice starch of 1:10. The lipid used is myristic acid. Stir for 5 min at a speed of 550 rpm and stir at 90°C for 45 min in a water bath. Place the mixed solution at 4°C to cool and recrystallize for 2 h. Centrifuge at 4000 r / min for 20 min. Then wash with anhydrous ethanol to remove unreacted lipids and centrifuge at 4000 r / min for 10 min. Repeat the ethanol washing and centrifugation twice. Then place the precipitate at -80°C for rapid freezing. After complete freezing, freeze dry for 24 h. After drying, pulverize and pass through an 80 mesh sieve to obtain the starch-myristic acid complex. The sample is named EA-RSMA.

[0095] Comparative Example 8

[0096] A method for preparing a starch-lipid complex includes the following steps:

[0097] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0098] (2) Add distilled water to the rice starch obtained in step (1) and homogenize to prepare rice starch milk with a concentration of 0.1 g / mL. Then place it in an ultrasonic crusher at room temperature with an ultrasonic power of 300 W and an ultrasonic time of 20 min. Place the probe about 5 cm below the liquid surface. During the ultrasonic treatment, use a low temperature water bath to control the reaction temperature and change the water in the water bath every 10 min. After the ultrasonic treatment, centrifuge the rice starch milk at 6000 r / min for 20 min, discard the supernatant, then add distilled water to wash, centrifuge at 4000 r / min for 10 min, repeat the washing and centrifugation twice to obtain the processed rice starch.

[0099] (3) Add distilled water to the treated rice starch obtained in step (2) and homogenize to prepare a suspension with a concentration of 0.1 g / mL. Then, add lipids at a mass ratio of 1:10 to the treated rice starch. The lipid used is myristic acid. Stir for 5 min at a speed of 550 rpm and stir at 90°C for 45 min in a water bath. Cool the mixture at 4°C for 2 h to recrystallize. Centrifuge at 4000 r / min for 20 min. Then wash with anhydrous ethanol to remove unreacted lipids and centrifuge at 4000 r / min for 10 min. Repeat the ethanol washing and centrifugation twice. Then place the precipitate at -80°C for rapid freezing. After complete freezing, freeze dry for 24 h. After drying, pulverize and pass through an 80 mesh sieve to obtain the starch-myristic acid complex. The sample is named US-RSMA.

[0100] Comparative Example 9

[0101] A method for preparing a starch-lipid complex includes the following steps:

[0102] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0103] (2) Add distilled water to the rice starch obtained in step (1) to prepare a rice suspension with a concentration of 0.1 g / mL. Add 3.0 mol / L NaOH solution slowly according to the mass ratio of rice suspension to NaOH solution of 1:1 to adjust the pH to about 10.6. Then place it in an ultrasonic crusher at room temperature with an ultrasonic power of 300W and an ultrasonic time of 20 min. Place the probe about 5 cm below the liquid surface. Use a low temperature water bath to control the reaction temperature during the ultrasonic treatment and change the water in the water bath every 10 min. After the ultrasonic treatment, add 0.3 mol / L HCl aqueous solution to adjust the pH to neutral. Then centrifuge the rice starch milk at 6000 r / min for 20 min, discard the supernatant, add distilled water to wash, centrifuge at 4000 r / min for 10 min, repeat the washing and centrifugation twice to obtain the processed rice starch.

[0104] (3) Add distilled water to the treated rice starch obtained in step (2) and homogenize to prepare a suspension with a concentration of 0.1 g / mL. Then, add lipids according to the mass ratio of lipids to treated rice starch of 1:10. Myristic acid was selected as the lipid. Stir for 5 min at a speed of 550 rpm and stir at 90°C for 45 min in a water bath. Place the mixed solution at 4°C to cool and recrystallize for 2 h. Centrifuge at 4000 r / min for 20 min. Then wash with anhydrous ethanol to remove unreacted lipids and centrifuge at 4000 r / min for 10 min. Repeat the ethanol washing and centrifugation twice. Then place the precipitate at -80°C for rapid freezing. After complete freezing, freeze dry for 24 h. After drying, pulverize and pass through an 80 mesh sieve to obtain the starch-myristic acid complex. The sample was named AUS-RSMA.

[0105] Comparative Example 10

[0106] A method for preparing a starch-lipid complex includes the following steps:

[0107] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0108] (2) Add a 70wt% ethanol solution to the rice starch obtained in step (1) and homogenize to prepare a rice starch milk with a concentration of 0.1g / mL. Place it in a magnetic constant temperature water bath and stir. Control the temperature at 40℃ and the speed at 250rpm. During the stirring process, slowly add a 3.0mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:1 to adjust the pH to about 10.6. Continue stirring for 30min. After stirring is completed, add a 0.3mol / L HCl aqueous solution to adjust the pH to neutral to obtain the processed rice starch milk.

[0109] (3) The processed rice starch milk obtained in step (2) was placed in a high-pressure homogenizer at room temperature. The homogenization pressure was 100 MPa and the homogenization time was 10 min. After the high-pressure homogenization was completed, the rice starch milk was centrifuged at 6000 r / min for 20 min. The supernatant was discarded, and then distilled water was added for washing. The mixture was centrifuged at 4000 r / min for 10 min. The washing and centrifugation were repeated twice to obtain the processed rice starch.

[0110] (4) Add distilled water to the treated rice starch obtained in step (3) and homogenize to prepare a suspension with a concentration of 0.1 g / mL. Then, add lipids according to the mass ratio of lipids to treated rice starch of 1:10. Myristic acid was selected as the lipid. Stir for 5 min at a speed of 550 rpm and stir at 90°C for 45 min in a water bath. Place the mixed solution at 4°C to cool and recrystallize for 2 h. Centrifuge at 4000 r / min for 20 min. Then wash with anhydrous ethanol to remove unreacted lipids and centrifuge at 4000 r / min for 10 min. Repeat the ethanol washing and centrifugation twice. Then place the precipitate at -80°C for rapid freezing. After complete freezing, freeze dry for 24 h. After drying, pulverize and pass through an 80 mesh sieve to obtain the starch-myristic acid complex. The sample was named EA-HH-RSMA.

[0111] Comparative Example 11

[0112] A method for preparing a starch-lipid complex includes the following steps:

[0113] (1) The rice was crushed into rice flour with a particle size greater than 80 mesh. Then, it was soaked in a 0.1 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:3. After stirring for 2 hours, the pH was adjusted to 7.0 with a 0.1 mol / L HCl aqueous solution. After centrifugation at 4000 r / min for 10 min, the supernatant was discarded. The mixture was washed and centrifuged 3 times. Then, anhydrous ethanol was added at a solid-liquid mass ratio of 1:1. After stirring for 1 hour, the mixture was centrifuged at 4000 r / min for 10 min. After discarding the supernatant, the mixture was washed and centrifuged 3 times to obtain white rice starch precipitate. Then, it was dried in an oven at 45℃ for 12 hours, crushed and passed through an 80 mesh sieve to obtain rice starch.

[0114] (2) Add a 70wt% ethanol solution to the rice starch obtained in step (1) and homogenize to prepare a rice starch milk with a concentration of 0.1g / mL. Place it in a magnetic constant temperature water bath and stir. Control the temperature at 40℃ and the speed at 250rpm. During the stirring process, slowly add a 3.0mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:1 to adjust the pH to about 10.6. Continue stirring for 30min to obtain the processed rice starch milk.

[0115] (3) Place the processed rice starch milk obtained in step (2) in an ultrasonic crusher at room temperature, with an ultrasonic power of 300W and an ultrasonic time of 20min. Place the probe about 5cm below the liquid surface. Use a low-temperature water bath to control the reaction temperature during the ultrasonic treatment and change the water in the water bath every 10min. After the ultrasonic treatment is completed, ultrasonic rice starch milk is obtained.

[0116] (4) The ultrasonic rice starch milk obtained in step (3) was added to the lipid at a mass ratio of 1:10 (the lipid was myristic acid). The stirring time was 5 min and the speed was 550 rpm. The mixture was stirred at 90°C for 45 min in a water bath. The mixture was cooled and recrystallized at 4°C for 2 h. It was centrifuged at 4000 r / min for 20 min. Then anhydrous ethanol was added to wash away unreacted lipids. 0.3 mol / L HCl aqueous solution was added to adjust the pH to neutral. The mixture was centrifuged at 4000 r / min for 10 min. The ethanol washing and centrifugation were repeated twice. The precipitate was then placed at -80°C for rapid freezing. After it was completely frozen, it was freeze-dried for 24 h. After drying, it was pulverized and passed through an 80-mesh sieve to obtain the starch-myristic acid complex. The sample was named EA-US-ARSMA.

[0117] Performance testing

[0118] 1. Starch-lipid complex complex index: Weigh 1.0 g of the sample prepared in Example 1 or Comparative Examples 1, 6-11 into a 50 mL centrifuge tube, add distilled water to prepare a 10% suspension, then place the centrifuge tube in an 80℃ water bath and heat and stir for 30 min to allow the sample to completely gelatinize. After cooling to room temperature, a gelatinized starch sample is obtained. Add 50 mL of distilled water to the gelatinized starch sample, vortex for 2 min to mix, centrifuge at 4000 r / min for 10 min, take 0.5 mL of the supernatant, add 15 mL of distilled water and 2 mL of iodine solution (2.0% KI + 1.3% I2) respectively, mix well, let stand for 10 min for color development, and measure the absorbance values ​​A0 and A of the gelatinized starch sample at 690 nm. Each sample is measured three times. The gelatinized starch sample of Comparative Example 1 is used as the control group. The complex index (CI) is calculated according to the following formula:

[0119]

[0120] In the formula, A0 is the absorbance of the gelatinized starch sample in Comparative Example 1, A is the absorbance of the gelatinized starch sample in Example 1 or Comparative Examples 6-11, and the composite index CI is as follows: Figure 2 As shown.

[0121] like Figure 2As shown, the composite index of the conventionally prepared starch-lipid complex (RSMA) in Comparative Example 6 was 48.55%. Compared with Comparative Example 6, the composite of Example 1, which was treated with ethanol and alkali followed by ultrasonic treatment, had a higher composite index of 73.77%. This may be because the ethanol and alkali treatment caused the starch double helix structure to unwind into a single helix structure, inducing the starch to form a V-shaped hydrophobic cavity structure, which is beneficial for the adsorption between starch particles and lipid molecules. Ultrasonic treatment can induce the transformation of the starch molecule's double helix structure into a single helix structure, making the expansion of the hydrophobic cavity structure inside the starch more easily exposed, which is beneficial for the adsorption and interaction between starch particles and lipid molecules, and synergistically improves the starch-lipid composite effect.

[0122] Furthermore, compared to Example 1, the complexation indices of Comparative Example 7 (treated with ethanol and alkali alone, EA-RSMA) and Comparative Example 8 (treated with ultrasound alone, complex, US-RSMA) were 59.24% and 54.22%, respectively, indicating a decrease in the complexation index. This suggests that compared to single treatment with ethanol and alkali or ultrasound treatment, the combination of ethanol and alkali with ultrasound treatment can synergistically promote the formation of more hydrophobic cavity structures by starch molecules, thereby facilitating the adsorption and complexation between starch and lipid molecules.

[0123] Comparative Example 9, which involved dissolving rice starch in alkali followed by ultrasonic treatment (AUS-RSMA), showed a composite index of 67.21%, lower than that of Example 1. This is because Example 1 used ethanol and alkali to treat the starch simultaneously. The interaction between the -OH groups in the alkali solution and the -OH groups on the glucose residues of the starch granules caused the granules to acquire a negative charge. The mutual repulsion between starch molecules promoted the swelling of the starch granules and caused the double helix structure of the starch to unwind. Ethanol simultaneously inhibited the swelling of the starch granules, thus maintaining the integrity of the granules. The combined effect of the alkali solution and ethanol allowed the starch to maintain its granule shape while promoting the formation of a hydrophobic helical cavity structure, which, together with the subsequent ultrasonic treatment, improved the composite index between starch granules and lipid molecules. In contrast, in Comparative Example 9, after the alkali solution swollen the starch granules, it could not effectively inhibit the swelling to maintain the integrity of the granules, resulting in an incomplete starch morphology and thus affecting the subsequent composite index with lipids.

[0124] Compared to Example 1, Comparative Example 10 used high-pressure homogenization instead of ultrasonic treatment (EA-HH-RSMA). High-pressure homogenization forces the starch suspension through a narrow homogenization valve under high pressure, generating strong mechanical forces that induce the depolymerization and breakage of starch molecular chains, thereby altering the multi-scale structure of starch. In Example 1, ultrasonic treatment utilizes the cavitation effect and strong shear force generated by the periodic compression and expansion of sound waves in the liquid, leading to the breakage of starch molecular chains and the depolymerization of the double helix structure, thus altering the multi-scale structure of starch. The ultrasonic treatment in Example 1 exhibits a higher composite index than the high-pressure homogenization treatment in Comparative Example 10, indicating that the synergistic effect of ultrasonic treatment combined with ethanol and alkali treatment is optimal.

[0125] In Comparative Example 11, the starch granules and lipid molecules complexed under alkaline conditions (EA-US-ARSMA), with a complexation index of 70%, which was lower than the complexation index of starch granules and lipid molecules under neutral conditions in Example 1. This is because hydrophobic interactions are the core driving force for the formation of starch-lipid complexes. Under neutral pH conditions, myristic acid lipids typically maintain a neutral molecular state, which has high hydrophobicity. The internal cavity structure of amylose molecules is also mainly a hydrophobic environment. Therefore, under neutral conditions, lipid molecules can form starch-lipid complexes with amylose through hydrophobic interactions. Under alkaline conditions, the carboxyl group (R-COOH) in myristic acid lipid molecules undergoes deprotonation, transforming into a carboxylate ion (R-COO-), which is a negatively charged hydrophilic ion. This significantly reduces the hydrophobicity of the myristic acid lipid molecule itself. Simultaneously, there may be electrostatic repulsion between the negatively charged myristic acid lipid molecule and the uncharged or slightly negatively charged amylose. The combined effect of these two factors significantly weakens the binding driving force between the myristic acid lipid molecule and the internal cavity structure of amylose, thereby interfering with and reducing the complexation effect of starch and myristic acid lipid.

[0126] 2. Infrared Spectroscopy of Starch-Lipid Complex: Infrared spectroscopy analysis of Sample 1 and Comparative Examples 1 and 5-11 was performed using a Fourier Transform Infrared Spectrometer (Nicolet 6700, Thermo Nicolet, USA). The test conditions were as follows: wavelength range 650 cm⁻¹. -1 -4000cm -1 The resolution is 4cm. -1 Using air as the blank scanning background, 64 scans were performed. The collected spectra were analyzed using OMNIC software (OMNIC 8.0), with a 1200 cm⁻¹ depth selected. -1 -800cm -1 The regional infrared spectrum was subjected to Fourier self-deconvolution processing with a bandwidth set to 23 cm⁻¹. -1 The enhancement factor was set to 2.3 to obtain the deconvolution spectrum. The sample was viewed at 1047 cm⁻¹. -1 and 1022cm -1 The peak intensity, calculate R 1047 / 1022 To characterize the short-range ordered structure of the sample, the infrared spectroscopy results are as follows: Figure 3-4 As shown.

[0127] like Figure 3 The results showed that, compared with the RS sample of Comparative Example 1, the starch-lipid complexes (RSMA, EA-RSMA, US-RSMA, EA-HH-RSMA, AUS-RSMA, EA-US-ARSMA, EA-US-RSMA) of Examples 1 and Comparative Examples 6-11 all had a range of 2850 cm⁻¹. -1and 1700cm -1 The presence of distinct absorption peaks indicates that the lipid molecules enter the helical cavity of the starch molecule through hydrophobic interactions, forming a starch-lipid complex. The starch-lipid complexes (RSMA, EA-RSMA, US-RSMA, EA-HH-RSMA, AUS-RSMA, EA-US-ARSMA, EA-US-RSMA) in Examples 1 and Comparative Examples 6-11 showed no new absorption peaks or changes in the positions of characteristic peaks, indicating that the starch did not form new chemical bonds or functional groups after treatment with ethanol and alkali, or ultrasonic or high-pressure homogenization.

[0128] Studies have shown that starch at 1047 cm⁻¹ -1 and 1022cm -1 The changes in peak intensity of nearby infrared absorption characteristic peaks reflect the changes in starch crystalline structure and amorphous structure, respectively. Therefore, R 1047 / 1022 (1047cm -1 / 1022cm -1 The ratio of (to / to) can be used to characterize the short-range ordered structure of starch surface. The wavenumber of the characteristic absorption peak corresponding to this test sample is 1051 cm⁻¹. -1 and 1020cm -1 .like Figure 4 As shown in Comparative Example 6, the conventional preparation of starch-lipid complex (RSMA) is performed using R... 1051 / 1020 The value was 0.64; compared to Comparative Example 6, the R of the powder-lipid complex (EA-US-RSMA) in Example 1, which was treated with ethanol and alkali followed by ultrasonic treatment, was significantly higher. 1051 / 1020 Significantly improved, to 1.55.

[0129] Furthermore, compared to Example 1, Comparative Example 7, which used ethanol and alkali alone, and Comparative Example 8, which used ultrasonic treatment alone, prepared starch-lipid complexes (EA-RSMA, US-RSMA) with higher R... 1051 / 1020 The values ​​were 0.87 and 0.75 respectively, which were significantly reduced. This indicates that the ultrasonic treatment using a combination of ethanol and alkali in Example 1 can synergistically form more hydrophobic cavity structures for starch molecules, promote adsorption and recombination between starch and lipid molecules, and thus form a single helix and locally densely arranged ordered structure in the system.

[0130] Comparative Example 9 involved dissolving rice starch with alkali followed by ultrasonic treatment (AUS-RSMA), and its R... 1051 / 1020The value was 1.24, lower than that of Example 1. This is because Example 1 used ethanol and alkali to treat starch simultaneously. The alkali solution promoted the swelling of starch granules, causing the double helix structure of starch to unwind, while ethanol simultaneously inhibited the swelling of starch granules, thus maintaining the integrity of the granules. The combined effect of the alkali solution and ethanol allowed starch molecules to form a hydrophobic helical cavity structure while maintaining the granule shape, improving the adsorption and recombination of starch granules with lipid molecules, thereby forming a single helix and locally densely arranged ordered structure within the system. In contrast, in Comparative Example 9, after the alkali solution swollen the starch granules, it could not effectively inhibit the swelling to maintain the integrity of the granules. The incomplete starch morphology affected subsequent recombination with lipids, reducing the formation of single helices and locally densely arranged ordered structures within the system.

[0131] Compared to Example 1, Comparative Example 10 uses high-pressure homogenization instead of ultrasonic treatment (EA-HH-RSMA). High-pressure homogenization forces the starch suspension through a narrow homogenization valve under high pressure, generating strong mechanical forces that induce the depolymerization and breakage of starch molecular chains, thereby altering the multi-scale structure of starch. The ultrasonic treatment in Example 1 utilizes the cavitation effect and strong shear force generated by the periodic compression and expansion of sound waves in the liquid, leading to the breakage of starch molecular chains and the depolymerization of the double helix structure, thus altering the multi-scale structure of starch. The R... 1051 / 1020 Compared to the R of the high-pressure homogenization treatment in Comparative Example 10 1051 / 1020 The higher value indicates that the synergistic effect of ultrasonic treatment combined with ethanol and alkali treatment is optimal.

[0132] 3. Raman spectroscopy of starch-lipid complex: Raman spectroscopy analysis of samples from Example 1 and Comparative Examples 1 and 5-11 was performed using a laser confocal Raman spectrometer (Invia Reflex, Renishaw, UK). The instrument was calibrated before testing, and the silicon wafer was placed at 520 cm⁻¹. -1 Weigh an appropriate amount of sample and spread it evenly on a glass slide. Then, place the slide in the sample slot and adjust the focus to ensure a clear image of the sample. Turn off the white light and perform a Raman test under a laser light source. The Raman test conditions are as follows: a 785nm green diode laser light source with a resolution of 7cm. -1 The scanning range is 3200cm. -1 -100cm -1 The Raman spectrum was analyzed and processed using Omnic software to obtain the sample 480 cm⁻¹. -1 The full width at half maximum (FWHM) is used to characterize the short-range ordered structure of the starch-lipid complex sample. Raman spectroscopy results are as follows: Figure 5-6 As shown.

[0133] like Figure 5As shown, no new absorption peaks or changes in the positions of characteristic peaks appeared in the starch-lipid complexes (RSMA, EA-RSMA, US-RSMA, EA-HH-RSMA, AUS-RSMA, EA-US-ARSMA, EA-US-RSMA) of Example 1 and Comparative Examples 6-11, indicating that no new chemical bonds or functional groups were generated in starch after treatment with ethanol and alkali, or ultrasonic or high-pressure homogenization.

[0134] Studies have shown that 480 cm⁻¹ in Raman spectra -1 The nearby characteristic peaks are closely related to the short-range ordered structure of starch, and their full width at half maximum (FWHM) shows a strong negative correlation with the degree of short-range ordering of the starch structure. That is, the higher the degree of short-range ordering of the starch structure, the higher its FWHM. -1 The smaller the FWHM of the nearby characteristic peaks, the better. Figure 6 As shown, the FWHM of the conventionally prepared starch-lipid complex (RSMA) in Comparative Example 6 was 13.79; compared with Comparative Example 6, the FWHM of the starch-lipid complex (EA-US-RSMA) in Example 1, which was treated with ethanol and alkali and then ultrasonically treated, was significantly reduced to 1.55.

[0135] Furthermore, compared to Example 1, the FWHM of starch-lipid complexes (EA-RSMA and US-RSMA) prepared by Comparative Example 7 using ethanol and alkali alone and Comparative Example 8 using ultrasonic treatment alone were significantly improved, reaching 12.45 and 13.166 respectively. This indicates that the ultrasonic treatment using ethanol and alkali in Example 1 can synergistically form more hydrophobic cavity structures for starch molecules, promoting adsorption and recombination between starch and lipid molecules, thereby significantly increasing the degree of short-range ordering in the system, which is consistent with the results of short-range ordered structures in infrared spectroscopy.

[0136] Comparative Example 9, which involved dissolving rice starch with alkali followed by ultrasonic treatment (AUS-RSMA), achieved an FWHM of 10.74, an improvement over Example 1. This is because Example 1 used both ethanol and alkali to treat the starch. The alkali promoted the swelling of starch granules, causing the double helix structure of starch to unwind, while ethanol inhibited the swelling, thus maintaining granule integrity. The combined effect of the alkali and ethanol allowed starch molecules to form hydrophobic helical cavities while maintaining granule morphology, enhancing the adsorption and recombination of starch granules with lipid molecules. This resulted in the formation of single-helical and locally densely arranged ordered structures within the system. In contrast, in Comparative Example 9, the alkali solution, after swelling the starch granules, failed to effectively inhibit swelling and maintain granule integrity. The incomplete starch morphology affected subsequent recombination with lipids, reducing the formation of single-helical and locally densely arranged ordered structures within the system.

[0137] Compared to Example 1, Comparative Example 10 used high-pressure homogenization instead of ultrasonic treatment (EA-HH-RSMA). High-pressure homogenization involves forcing the starch suspension through a narrow homogenization valve under high pressure, generating strong mechanical forces that induce the depolymerization and breakage of starch molecular chains, thereby altering the multi-scale structure of starch. In Example 1, ultrasonic treatment utilizes the cavitation effect and strong shear force generated by the periodic compression and expansion of sound waves in the liquid, leading to the breakage of starch molecular chains and the depolymerization of the double helix structure, thus altering the multi-scale structure of starch. The FWHM of the ultrasonic treatment in Example 1 was lower than that of the high-pressure homogenization treatment in Comparative Example 10, indicating that the synergistic effect of ultrasonic treatment combined with ethanol and alkali treatment is optimal.

[0138] 4. X-ray diffraction of starch-lipid complex: X-ray diffraction analysis was performed on samples from Example 1 and Comparative Examples 1, 5-11 using an X-ray diffractometer (MAX2500VL, Rigaku Corporation, Japan). The X-ray diffractometer test conditions were as follows: Cu-Kα radiation at a wavelength of 0.1542 nm, voltage of 40 kV, current of 40 mA, diffraction angle (2θ) scanning range of 5°-50°, scanning rate of 5° / min, and step size of 0.05°. The crystallinity of the samples was calculated using MDI Jade 9 software, and the V-type crystal content of the starch complex samples was calculated using PeakFit 4.12 software for peak fitting of the X-ray diffraction patterns. The crystallinity test results are shown below. Figure 7-8 As shown.

[0139] like Figure 7As shown, the RS sample of Comparative Example 1 exhibits distinct characteristic peaks at 15.4°, 17.4°, 18.2°, and 23.2°, indicating a typical type A crystalline structure. Compared to RS, the GRS sample of Comparative Example 5 shows a smaller characteristic peak at 20.3°, suggesting that GRS has an A+V crystalline structure. This may be because starch molecules form starch-lipid complexes with endogenous lipids under the influence of heat and water molecules. Compared to GRS, the starch-lipid complexes (RSMA, EA-RSMA, US-RSMA, EA-HH-RSMA, AUS-RSMA, EA-US-ARSMA, EA-US-RSMA) of Examples 1 and Comparative Examples 6-11 all show distinct characteristic peaks at 7.9°, 13.5°, and 20.3°, indicating that the starch-lipid complexes have a type V crystalline structure. Furthermore, the starch-lipid complexes (RSMA, EA-RSMA, US-RSMA, EA-HH-RSMA, AUS-RSMA, EA-US-ARSMA, EA-US-RSMA) of Example 1 and Comparative Examples 6-11 all exhibited two distinct characteristic diffraction peaks at diffraction angles of 2θ of 21.8° and 24.2°, which are caused by the aggregation of free lipid molecules. No new characteristic peaks appeared in the starch-lipid complexes (RSMA, EA-RSMA, US-RSMA, EA-HH-RSMA, AUS-RSMA, EA-US-ARSMA, EA-US-RSMA) of Example 1 and Comparative Examples 6-11, indicating that ethanol and alkali treatment, as well as ultrasonic or high-pressure homogenization, do not alter the crystalline structure.

[0140] like Figure 8 As shown, the content of V-type crystals in the conventionally prepared starch-lipid complex (RSMA) of Comparative Example 6 was 4.49%; compared with Comparative Example 6, the content of V-type crystals in the starch-lipid complex (EA-US-RSMA) of Example 1, which was treated with ethanol and alkali and then ultrasonically treated, was significantly increased to 13.65%.

[0141] Furthermore, the starch-lipid complexes (EA-RSMA and US-RSMA) prepared by Comparative Example 7 using ethanol and alkali alone, and Comparative Example 8 using ultrasonic treatment alone, were significantly reduced, by 8.16% and 6.68%, respectively. This indicates that the ultrasonic treatment using ethanol and alkali in Example 1 can synergistically unwind the double helix structure of starch molecules into a single helix structure, induce starch molecules to form more hydrophobic cavity structures, and further expand the hydrophobic cavity structure, thereby promoting the entry of lipid molecules into the hydrophobic cavity structure of starch molecules to form a single helix complex. The single helix structure is closely related to the formation of V-shaped crystal structure, and therefore has a high degree of V-shaped crystallinity.

[0142] Comparative Example 9, which involved dissolving rice starch in alkali followed by ultrasonic treatment (AUS-RSMA), showed a V-type crystal content of 11.07%, lower than that of Example 1. This is because Example 1 used both ethanol and alkali to treat the starch. The alkali promoted the swelling of starch granules, causing the double helix structure of starch to unwind, while ethanol inhibited the swelling, thus maintaining granule integrity. The combined effect of the alkali and ethanol allowed starch molecules to form a hydrophobic single-helix cavity structure while maintaining granule morphology. This single-helix structure is closely related to the formation of V-type crystal structure, resulting in a high degree of V-type crystallinity. In contrast, in Comparative Example 9, the alkali solution, after swelling the starch granules, could not effectively inhibit swelling to maintain granule integrity, thus reducing the single-helix structure within the system.

[0143] Compared to Example 1, Comparative Example 10 used high-pressure homogenization instead of ultrasonic treatment (EA-HH-RSMA). High-pressure homogenization forces the starch suspension through a narrow homogenization valve under high pressure, generating strong mechanical forces that induce the depolymerization and breakage of starch molecular chains, thereby altering the multi-scale structure of starch. In Example 1, ultrasonic treatment utilizes the cavitation effect and strong shear force generated by the periodic compression and expansion of sound waves in the liquid, leading to the breakage of starch molecular chains and the depolymerization of the double helix structure, thus changing the multi-scale structure of starch. The V-crystal content of the ultrasonic treatment in Example 1 was higher than that of the high-pressure homogenization treatment in Comparative Example 10, indicating that the synergistic effect of ultrasonic treatment combined with ethanol and alkali treatment is optimal.

[0144] 5. Digestive performance of starch-lipid complex: Weigh 1.0 g of the sample from Example 1 or Comparative Examples 1-11 into a 100 mL centrifuge tube and add 5 glass beads (simulating the gastrointestinal peristalsis environment). Add 20 mL of sodium acetate buffer (0.5 mol / L, pH = 5.2), followed by 10 mL of mixed enzymatic hydrolysate (290 U / mL porcine pancreatic α-amylase and 15 U / mL saccharifying enzyme). Vortex for 2 min to mix. Place the 100 mL centrifuge tube in a constant temperature shaking water bath at 37°C and 150 rpm for enzymatic hydrolysis. At the start of timing, 1.0 mL of the reaction solution was added to a 10 mL centrifuge tube at 0 min, 20 min, and 120 min. After adding 5 mL of anhydrous ethanol to inactivate the enzyme, the tubes were centrifuged at 4000 rpm for 10 min. Then, 0.25 mL of the supernatant was aspirated and the absorbance of the supernatant at 510 nm was measured using a glucose assay kit and a microplate reader (M200PRO, TECAN, Switzerland). The contents of rapidly digestible starch, slowly digestible starch, and resistant starch in the starch-lipid complex sample were calculated according to the following formula:

[0145] RDS(%) = G 20 ×0.9×100%

[0146] SDS(%) = (G120 -G 20 )×0.9×100%

[0147] RS (%) = 100% - RDS - SDS

[0148] In the formula, G 20 The glucose content (mmol / L) in the starch-lipid complex sample after 20 min of enzymatic hydrolysis. 120 The glucose content (mmol / L) in the starch-lipid complex sample after 120 min of enzymatic hydrolysis is given. RSD represents the percentage of rapidly digested starch; SDS represents the percentage of slowly digested starch; and RS represents the percentage of resistant starch. The test results for RSD, SDS, and RS are shown below. Figure 9-10 As shown.

[0149] like Figure 9 As shown, the SDS and RS contents in the RS sample of Comparative Example 1 were 17.94% and 14.49%, respectively. Comparative Examples 2-4 were rice starch samples treated with ethanol and different alkaline solutions (EA10, EA9, EA8). Compared with the RS sample of Comparative Example 1, the RS contents in Comparative Example 4 sample EA8 and Comparative Example 3 sample EA9 showed no significant change, while the SDS contents increased. In Comparative Example 2 sample EA10, the SDS and RS contents increased significantly, reaching 23.11% and 16.71%, respectively. This is because under appropriate alkaline conditions, the hydroxyl groups on the surface of starch granules undergo deprotonation, weakening the hydrogen bonds between the double helixes. The double helix structure unwinds into a single helix, forming a hydrophobic helical cavity structure. Due to steric hindrance, the helical cavity structure hinders the approach of α-amylase, thus improving the starch's resistance to digestion.

[0150] like Figure 10 As shown, in Comparative Example 6, the SDS content and RS content in the conventionally prepared starch-lipid complex (RSMA) were 18.11% and 32.01%, respectively. Compared with Comparative Example 6, the SDS content and RS content in the starch-lipid complex (EA-US-RSMA) of Example 1, which was treated with ethanol and alkali and then ultrasonically treated, were significantly increased to 40.76% and 32.49%, respectively.

[0151] Furthermore, compared to Example 1, the SDS and RS contents of starch-lipid complexes (EA-RSMA and US-RSMA) prepared by Comparative Example 7 (treated with ethanol and alkali alone) and Comparative Example 8 (treated with ultrasound alone) were significantly reduced, at 35.22% and 25.93%, and 34.50% and 23.24%, respectively. This indicates that the combined ultrasonic treatment with ethanol and alkali in Example 1 can synergistically help starch molecules form more hydrophobic cavity structures and further expand these structures. This promotes the entry of lipid molecules into the hydrophobic cavity structures of starch molecules to form single-helix complexes, which in turn promotes a tighter arrangement of starch molecular chains, thereby reducing the rate and extent of starch hydrolysis and improving the anti-digestion properties of starch.

[0152] Comparative Example 9, which involved dissolving rice starch with alkali followed by ultrasonic treatment (AUS-RSMA), showed SDS and RS contents of 38.45% and 29.49%, respectively, lower than that of Example 1. This is because Example 1 used both ethanol and alkali to treat the starch. The alkali promoted starch granule swelling and unwinding of the starch double helix structure, while ethanol inhibited swelling, thus maintaining granule integrity. The combined effect of alkali and ethanol allowed starch molecules to form hydrophobic single-helix cavities while maintaining granule shape. Lipid molecules entered these cavities to form single-helix complexes, promoting tighter chain arrangement and reducing the rate and extent of starch hydrolysis, thereby improving the starch's resistance to digestion. In contrast, the alkali solution in Comparative Example 9, after swelling the starch granules, failed to effectively inhibit swelling and maintain granule integrity, reducing the formation of hydrophobic cavities and thus lowering the starch's resistance to digestion.

[0153] Compared to Example 1, Comparative Example 10 used high-pressure homogenization instead of ultrasonic treatment (EA-HH-RSMA). High-pressure homogenization involves forcing the starch suspension through a narrow homogenization valve under high pressure, generating strong mechanical forces that induce the depolymerization and breakage of starch molecular chains, thereby altering the multi-scale structure of starch. In Example 1, ultrasonic treatment utilizes the cavitation effect and strong shear force generated by the periodic compression and expansion of sound waves in the liquid, leading to the breakage of starch molecular chains and the depolymerization of the double helix structure, thus altering the multi-scale structure of starch. The SDS and RS contents of the ultrasonic treatment in Example 1 were higher than those of the high-pressure homogenization treatment in Comparative Example 10, indicating that the synergistic effect of ultrasonic treatment combined with ethanol and alkali treatment is optimal.

[0154] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for preparing a starch-lipid complex, characterized in that, Includes the following steps: (1) Prepare starch milk by homogenizing ethanol solution and starch, stir and add alkaline solution to adjust pH to 10-11, and after stirring the reaction is complete, add acid solution to adjust to neutral to obtain processed starch milk; (2) The processed starch milk is subjected to ultrasonic treatment, centrifugation, and water washing to obtain processed starch; (3) Mix water and the treated starch and homogenize to prepare a suspension. Add lipids and stir to combine at a temperature of 80-100 °C. Then cool and recrystallize. After centrifugation, alcohol washing and drying, starch-lipid complex is obtained. In step (1), the concentration of ethanol in the ethanol solution is 60wt%-80wt%, the concentration of starch in the starch milk is 0.05-0.5 g / mL, the stirring reaction temperature is 25-45 ℃, the stirring reaction time is 20-60 min, and the stirring rate is 200-400 rpm. In step (2), the ultrasonic power is 250-350 W and the ultrasonic time is 15-30 min; In step (3), the lipid is at least one of myristic acid, lauric acid, palmitic acid, stearic acid, oleic acid, and linoleic acid. The mass ratio of starch to lipid in the suspension is 1:(8-12). The concentration of starch in the suspension is 0.05-0.5 g / mL. The stirring and compounding time is 30-60 min.

2. The method for preparing the starch-lipid complex according to claim 1, characterized in that, In step (1), the starch is prepared by alkaline extraction. And / or, in step (1), the starch includes at least one of rice starch, corn starch, tapioca starch, glutinous rice starch, and potato starch.

3. The method for preparing the starch-lipid complex according to claim 2, characterized in that, In step (1), the method for preparing the starch includes the following steps: After crushing the starch raw material to a particle size greater than 80 mesh, add a 0.1-0.3 mol / L NaOH aqueous solution at a solid-liquid mass ratio of 1:(2-4). Stir for 1-3 h, adjust the pH to neutral with an acid solution, centrifuge, wash with water, and then add ethanol to the precipitate at a solid-liquid mass ratio of 1:(1-2). Stir for 1-2 h, centrifuge, wash with water, dry, and sieve to obtain starch.

4. The method for preparing the starch-lipid complex according to claim 1, characterized in that, In step (1), the alkali in the alkaline solution is at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, and potassium hydroxide, and the concentration of the alkali in the alkaline solution is 0.1-5 mol / L; And / or, in step (1), the acid in the acid solution is at least one of hydrochloric acid, sulfuric acid, acetic acid, and phosphoric acid, and the concentration of the acid solution is 0.1-0.5 mol / L.

5. The method for preparing the starch-lipid complex according to claim 1, characterized in that, In step (3), the cooling recrystallization temperature is 3-5 ℃ and the time is 1-3 h; And / or, in step (3), drying is performed by freeze-drying at -85 to -75 °C for 12-36 h; And / or, in step (3), the sieve mesh size is 80-100 mesh.

6. The method for preparing the starch-lipid complex according to claim 1, characterized in that, In steps (2) and (3), the centrifugation rate is 3000-8000 r / min.

7. The method for preparing the starch-lipid complex according to claim 6, characterized in that, In step (2), the water washing involves adding water and then centrifuging at a rate of 3000-6000 r / min, and repeating the washing 2-5 times. And / or, in step (3), alcohol washing is to add ethanol for washing and then centrifuge at a rate of 3000-6000 r / min, and repeat the washing 2-5 times.

8. A starch-lipid complex prepared by the method for preparing starch-lipid complex according to any one of claims 1-7.

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