A method for preparing starch-lipid complex by combined pressurized heating and enzymatic hydrolysis, and products and applications thereof

Abstract

The present application relates to a kind of starch-lipid complex prepared by autoclaving combined enzymatic hydrolysis method and its product and application, the method comprises: (1) starch is mixed with water to obtain starch suspension, autoclaving is carried out in autoclave, and starch paste is obtained;(2) starch paste and pullulanase, isoamylase are mixed, and debranching reaction is carried out, and enzyme hydrolysis mixture is obtained;(3) enzyme hydrolysis mixture and alpha-amylase are mixed, and debranching starch paste is obtained;(4) debranching starch paste and lipid are mixed, and complex reaction is carried out, after reaction, crystallization treatment, microwave treatment are carried out, and the starch-lipid complex is obtained.The present application designs a kind of preparation method of starch-lipid complex, the technical scheme of first debranching, then endo after autoclaving can make three enzymes play maximum limit synergistic effect, realize the accurate cutting of starch molecule, lay foundation for preparing high-performance starch-lipid complex.

Description

Technical Field

[0001] This invention belongs to the field of functional food technology, and relates to a method for preparing starch-lipid complexes by pressure heating combined with enzymatic hydrolysis, as well as its products and applications. Background Technology

[0002] Resistant starch (RS) refers to starch and its degradation products that cannot be digested and absorbed by the human small intestine but can be fermented and utilized by intestinal flora in the large intestine. Based on their source and structural characteristics, resistant starch can be divided into five categories: RS1 (physically encapsulated starch), RS2 (natural resistant starch granules), RS3 (retrograded starch), RS4 (chemically modified starch), and RS5 (starch-lipid complex). Among them, RS5 resistant starch is a single-helix inclusion complex formed by the hydrophobic interaction between amylose and lipid molecules. It possesses outstanding advantages such as extremely high thermal stability, strong resistance to digestion, and good processing tolerance, and has broad application prospects in high-temperature processed foods such as baked and fried foods.

[0003] Existing methods for preparing starch-lipid complexes mainly include water bath heating, high-pressure cooking, extrusion, and microwave-assisted methods. However, these methods generally have the following technical defects: (1) Traditional water bath heating has low temperature and slow heat transfer, resulting in insufficient starch gelatinization and limited release of amylose, leading to low lipid complexation rate (usually less than 30%); (2) Although high-pressure cooking can improve the degree of gelatinization, it has high energy consumption and large equipment investment, and prolonged high temperature can easily lead to excessive degradation of starch molecules, producing a large amount of by-products such as maltose and glucose, reducing the yield; (3) Extrusion requires high equipment, and the shear and thermal effects are difficult to control precisely, resulting in poor batch stability of products; (4) Existing methods mostly use native starch directly to complex lipids without fully considering the steric hindrance effect of amylopectin on the complexation site, resulting in a large amount of amylopectin being unable to participate in helical inclusion, leading to low raw material utilization.

[0004] Therefore, developing a method for preparing RS5-type resistant starch that can efficiently release amylose, improve lipid complexation rate, reduce energy consumption, and is suitable for industrial scale-up is of great significance for promoting the industrial application of functional starch. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing starch-lipid complexes by pressure heating combined with enzymatic hydrolysis, as well as the products and applications thereof.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing starch-lipid complexes by pressure heating combined with enzymatic hydrolysis, the method comprising: (1) Mix starch with water to obtain a starch suspension, and perform pressure heat treatment in an autoclave to obtain starch paste; (2) Mix starch paste with pullulanase and isoamylase to carry out debranching reaction to obtain debranched starch paste; (3) Mix the debranched starch paste and α-amylase to obtain an enzymatically hydrolyzed mixture; (4) The enzymatic hydrolysate and lipids are mixed and subjected to a complex reaction. After the reaction, crystallization and microwave treatment are performed to obtain the starch-lipid complex.

[0007] This invention creatively designs a method for preparing a starch-lipid complex. First, starch is subjected to pressure heating, then combined with enzymatic hydrolysis and mixed with lipids, followed by crystallization and microwave treatment to obtain the starch-lipid complex. Pressure heating fully gelatinizes starch granules and extends molecular chains; debranching enzymes hydrolyze α-1,6-glycosidic bonds on starch branches, "cutting" amylopectin into linear chains, providing more linear substrates for subsequent enzymatic hydrolysis or complexation reactions; α-amylase, as an endonuclease, hydrolyzes α-1,4-glycosidic bonds within starch, "cutting" long-chain linear starch into shorter fragments, regulating the molecular weight of the product. The specific technical scheme of first debranching and then endonucleating used in this invention allows the three enzymes to exert maximum synergistic effects, achieving precise "tailoring" of starch molecules, laying the foundation for preparing high-performance starch-lipid complexes. Simultaneously, this invention also performs crystallization and microwave treatment after the debranched starch paste and lipid complexation reaction, promoting the orderly stacking and recrystallization of V-shaped crystals, thereby obtaining a starch-lipid complex with high complexation rate and high digestibility.

[0008] Preferably, the starch in step (1) includes any one or a combination of at least two of corn starch, wheat starch, and potato starch.

[0009] Preferably, the starch suspension in step (1) has a mass percentage of 8-12% (e.g., 8%, 9%, 10%, 11%, 12%, etc.).

[0010] Preferably, the pressure heat treatment is a stepped heating and cooling pressure heat treatment, specifically: the first stage is maintained at 95-105℃ (e.g., 95℃, 100℃, 105℃, etc.) for 10-15 min (e.g., 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, etc.); the second stage is maintained at 110-125℃ (e.g., 110℃, 115℃, 120℃, 125℃, etc.) for 30-60 min (e.g., 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc.); and the third stage is maintained at 85-95℃ (e.g., 85℃, 90℃, 95℃, etc.) for 5-15 min (e.g., 5 min, 10 min, 15 min, etc.).

[0011] Preferably, before mixing the starch paste with pullulanase and isoamylase in step (2), the step further includes adjusting the pH of the starch paste to 4.0-6.0 (e.g., 4.0, 4.5, 5.0, 5.5, 6.0, etc.) using a pH adjuster.

[0012] Preferably, the pH adjuster includes acetic acid.

[0013] Preferably, the mass ratio of pullulanase to isoamylase in step (2) is 1:(0.5-3) (for example, it can be 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.).

[0014] Preferably, the total amount of pullulanase and isoamylase added in step (2) is 0.02-1.5% of the dry basis mass of the starch paste (for example, it can be 0.02%, 0.05%, 0.1%, 0.15%, 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, etc.).

[0015] Preferably, the temperature of the debranching reaction in step (2) is 50-60℃ (e.g., 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, etc.), and the time is 0.5-8 h (e.g., 0.5 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 5 h, 6 h, 8 h, etc.).

[0016] Preferably, the α-amylase in step (3) accounts for 0.25-1.0% of the dry basis mass of the debranched starch paste (e.g., 0.25%, 0.5%, 0.75%, 1.0%, etc.).

[0017] Preferably, the temperature of the mixing reaction in step (3) is 50-60℃ (e.g., 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, etc.), and the time is 20-90 min (e.g., 20 min, 30 min, 50 min, 70 min, 90 min, etc.).

[0018] Preferably, the lipids in step (4) include any one or a combination of at least two of the following: lauric acid, linoleic acid, glyceryl monostearate, glyceryl stearate, stearic acid, myristic acid, and palmitic acid.

[0019] Preferably, the lipid in step (4) is a combination of lauric acid and linoleic acid.

[0020] Preferably, the mass ratio of lauric acid to linoleic acid is (5-8):(2-5) (where the specific values ​​of 5-8 can be 5, 6, 7, 8, etc., and the specific values ​​of 2-5 can be 2, 3, 4, 5, etc.).

[0021] Preferably, the amount of lipid added in step (4) is 0.2-5% of the dry basis mass of the enzymatic hydrolysate mixture (e.g., 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, etc.).

[0022] Preferably, the temperature of the composite reaction in step (4) is 60-95℃ (e.g., 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, etc.), and the time is 30-120 min (e.g., 30 min, 50 min, 70 min, 90 min, 110 min, 120 min, etc.).

[0023] Preferably, the crystallization treatment is performed at a temperature of 1-20°C (e.g., 1°C, 5°C, 10°C, 15°C, 20°C, etc.) and for a time of 36-72 h (e.g., 36 h, 48 h, 60 h, 72 h, etc.).

[0024] Preferably, the power of the microwave processing is 500-700 W (e.g., 500 W, 550 W, 600 W, 650 W, 700 W, etc.), and the time is 5-10 min (e.g., 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.).

[0025] Preferably, step (4) further includes drying and pulverizing steps after microwave treatment.

[0026] Preferably, the drying temperature is 105-200℃ (e.g., 105℃, 110℃, 120℃, 140℃, 160℃, 180℃, 200℃, etc.), and the time is 2-24 h (e.g., 2 h, 6 h, 12 h, 18 h, 24 h, etc.).

[0027] Preferably, the mesh size of the pulverized material is 80-100 mesh (e.g., 80 mesh, 85 mesh, 90 mesh, 95 mesh, 100 mesh, etc.).

[0028] All other specific point values ​​not listed above within the numerical ranges mentioned above can be selected and are all within the protection scope of this invention. For the sake of brevity, they will not be described in detail here.

[0029] In a second aspect, the present invention provides a starch-lipid complex prepared by the method described in the first aspect.

[0030] Thirdly, the present invention provides the use of the starch-lipid complex as described in the second aspect in the preparation of low glycemic index products and / or food stabilizers.

[0031] Compared with the prior art, the present invention has the following beneficial effects: This invention creatively designs a method for preparing a starch-lipid complex. First, starch is subjected to pressure heating, then combined with enzymatic hydrolysis and mixed with lipids, followed by crystallization and microwave treatment to obtain the starch-lipid complex. Pressure heating fully gelatinizes starch granules and extends molecular chains; debranching enzymes hydrolyze α-1,6-glycosidic bonds on starch branches, "cutting" amylopectin into linear chains, providing more linear substrates for subsequent enzymatic hydrolysis or compounding reactions; α-amylase, as an endonuclease, hydrolyzes α-1,4-glycosidic bonds within starch, "cutting" long-chain amylose into shorter fragments, regulating the molecular weight of the product; these amylose chains interact hydrophobically with lipids during the cooling compounding stage, with the lipid hydrocarbon chains entering the single-helix hydrophobic cavity of the amylose, forming a stable V-shaped inclusion complex. The specific technical scheme of first debranching and then endonucleating used in this invention allows the three enzymes to exert maximum synergistic effects, achieving precise "tailoring" of starch molecules, laying the foundation for the preparation of high-performance starch-lipid complexes. In addition, after the debranched starch paste and lipid complex reaction, the present invention also carried out crystallization and microwave treatment to promote the orderly accumulation and recrystallization of V-shaped crystals, thereby obtaining a starch lipid complex with high complexation rate and high digestibility. Detailed Implementation

[0032] To further illustrate the technical means and effects of the present invention, the following describes the technical solution of the present invention in conjunction with preferred embodiments of the present invention. However, the present invention is not limited to the scope of the embodiments.

[0033] The pullulanase used in this invention was purchased from Novozymes, brand name Promozyme® D6; the isoamylase was purchased from Sigma, brand name E2412; and the α-amylase was purchased from Novozymes, brand name Termozyme® SC DS.

[0034] Example 1 This embodiment provides a starch-lipid complex, prepared by the following method: (1) Mix corn starch and water to prepare a starch suspension with a starch content of 10%, place it in an autoclave for pressure heat treatment, first maintain at 100℃ for 15 min, then maintain at 121℃ for 45 min, and then cool down to 90℃ and maintain for 10 min to obtain starch paste. (2) The pH of the starch paste was adjusted to 4.5 using 1 M acetic acid, and then mixed with pullulanase and isoamylase in a mass ratio of 2:1. The total amount of the two enzymes added was 0.9% of the dry weight of the starch paste. After mixing, the starch paste was debranched by shaking in a water bath at 60°C for 3 h. (3) Mix the debranched starch paste and α-amylase, with α-amylase accounting for 0.5% of the dry weight of the debranched starch paste, and hydrolyze in a water bath at 60°C for 40 min to obtain the hydrolysate mixture; (4) The enzymatic hydrolysate and 5% of the dry weight of the mixture of lipids (lauric acid and linoleic acid in a mass ratio of 7:3) were mixed and reacted at a temperature of 70°C and stirred in a water bath for 30 min. After the reaction, the mixture was aged and crystallized at 4°C for 48 h, and then microwaved for 10 min at a microwave power of 600 W. After that, the mixture was dried at 105°C for 6 h and pulverized through a 100-mesh sieve to obtain the starch-lipid complex.

[0035] Example 2 This embodiment provides a starch-lipid complex, prepared by the following method: (1) Mix corn starch and water to prepare a starch suspension with a starch content of 12%, place it in an autoclave for pressure heat treatment, first maintain at 95℃ for 10 min, then maintain at 121℃ for 45 min, and then cool down to 85℃ and maintain for 8 min to obtain starch paste. (2) The pH of the starch paste was adjusted to 4.5 using 1 M acetic acid, and then mixed with pullulanase and isoamylase in a mass ratio of 1:1. The total amount of the two enzymes added was 0.8% of the dry weight of the starch paste. After mixing, the starch paste was debranched by shaking in a water bath at 60°C for 5 h. (3) Mix the debranched starch paste and α-amylase, with α-amylase accounting for 0.25% of the dry weight of the debranched starch paste, and hydrolyze in a water bath at 60°C for 30 min to obtain the hydrolysate mixture; (4) The enzymatic hydrolysate and 5% of the dry weight of the mixture of lipids (lauric acid and linoleic acid in a mass ratio of 6:4) were mixed and reacted at 85°C. The mixture was stirred in a water bath for 30 min. After the reaction, the mixture was aged and crystallized at 4°C for 48 h. Then it was microwaved for 10 min at a microwave power of 700 W. After that, it was dried at 105°C for 6 h and pulverized through a 100-mesh sieve to obtain the starch-lipid complex.

[0036] Example 3 This embodiment provides a starch-lipid complex, prepared by the following method: (1) Mix corn starch and water to prepare a starch suspension with a starch content of 8%, place it in an autoclave for pressure heat treatment, first maintain at 100℃ for 10 min, then maintain at 121℃ for 50 min, and then cool down to 85℃ and maintain for 12 min to obtain starch paste. (2) The pH of the starch paste was adjusted to 4.5 using 1 M acetic acid, and then mixed with pullulanase and isoamylase in a mass ratio of 1:2. The total amount of the two enzymes added was 0.9% of the dry weight of the starch paste. After mixing, the starch paste was debranched by shaking in a water bath at 60°C for 3 h. (3) Mix the debranched starch paste and α-amylase, with α-amylase accounting for 1% of the dry weight of the debranched starch paste, and hydrolyze in a water bath at 60°C for 20 min to obtain the hydrolysate mixture. (4) The enzymatic hydrolysate and 5% of the dry weight of the mixture of lipids (lauric acid and linoleic acid in a mass ratio of 7:3) were mixed and reacted at 60°C. The mixture was stirred in a water bath for 60 min. After the reaction, the mixture was aged and crystallized at 4°C for 48 h. Then it was microwaved for 8 min at a microwave power of 600 W. After that, it was dried at 105°C for 6 h and pulverized through a 100-mesh sieve to obtain the starch-lipid complex.

[0037] Example 4 This embodiment provides a starch-lipid complex. The preparation method differs from that of Example 1 only in that step (1) is: corn starch and water are mixed to prepare a starch suspension with a starch content of 10%, which is placed in an autoclave for pressure heat treatment and maintained at 121°C for 70 min to obtain starch paste. With other conditions kept constant, the starch-lipid complex was obtained.

[0038] Example 5 This embodiment provides a starch-lipid complex. The preparation method differs from that of Example 1 only in that lauric acid is not added in step (4), and the reduced mass of lauric acid is allocated to linoleic acid. All other conditions remain unchanged.

[0039] Example 6 This embodiment provides a starch-lipid complex. The preparation method differs from that of Example 1 only in that linoleic acid is not added in step (4), and the reduced mass of linoleic acid is allocated to lauric acid. All other conditions remain unchanged.

[0040] Comparative Example 1 This comparative example provides a starch-lipid complex, which is prepared by the following method: (1) Mix corn starch and water to prepare a starch suspension with a starch content of 10%. Use 1 M acetic acid to adjust the pH of the starch paste to 4.5. Then mix pullulanase and isoamylase with a mass ratio of 2:1. The total amount of the two enzymes added is 1% of the dry weight of the starch paste. After mixing, the mixture is subjected to debranching reaction by shaking in a water bath at 60°C for 3 h to obtain debranched starch paste. (2) Mix the debranched starch paste and α-amylase, with α-amylase accounting for 0.5% of the dry weight of the debranched starch paste, and hydrolyze in a water bath at 60°C for 40 min to obtain the hydrolysate mixture; (3) The enzymatic hydrolysate and 5% of the dry weight of the mixture of lipids (lauric acid and linoleic acid in a mass ratio of 7:3) were mixed and reacted at 70°C. The mixture was stirred in a water bath for 30 min. After the reaction, the mixture was aged and crystallized at 4°C for 48 h. Then it was microwaved for 10 min at a microwave power of 600 W. After that, it was dried at 105°C for 6 h and pulverized through a 100-mesh sieve to obtain the starch-lipid complex.

[0041] Comparative Example 2 This comparative example provides a starch-lipid complex, which is prepared by the following method: (1) Mix corn starch and water to prepare a starch suspension with a starch content of 10%, and heat it in a boiling water bath for 70 min to gelatinize it, so as to obtain starch paste; (2) The pH of the starch paste was adjusted to 4.5 using 1 M acetic acid, and then mixed with pullulanase and isoamylase in a mass ratio of 2:1. The total amount of the two enzymes added was 1% of the dry weight of the starch paste. After mixing, the starch paste was subjected to debranching reaction by shaking in a water bath at 60°C for 3 h to obtain debranched starch paste. (3) Mix the debranched starch paste and α-amylase, with α-amylase accounting for 0.5% of the dry weight of the debranched starch paste, and hydrolyze in a water bath at 60°C for 40 min to obtain the hydrolysate mixture; (4) The enzymatic hydrolysate and 5% of the dry weight of the mixture of lipids (lauric acid and linoleic acid in a mass ratio of 7:3) were mixed and reacted at a temperature of 70°C and stirred in a water bath for 30 min. After the reaction, the mixture was aged and crystallized at 4°C for 48 h, and then microwaved for 10 min at a microwave power of 600 W. After that, the mixture was dried at 105°C for 6 h and pulverized through a 100-mesh sieve to obtain the starch-lipid complex.

[0042] Comparative Example 3 This comparative example provides a starch-lipid complex. The preparation method differs from that of Example 1 only in that pullulanase is not added in step (2). The reduced mass of pullulanase is proportionally allocated to isoamylase and α-amylase, while other conditions remain unchanged.

[0043] Comparative Example 4 This comparative example provides a starch-lipid complex. The preparation method differs from that of Example 1 only in that isoamylase is not added in step (2), and the reduced mass of isoamylase is proportionally allocated to pullulanase and α-amylase, while other conditions remain unchanged.

[0044] Comparative Example 5 This comparative example provides a starch-lipid complex. The preparation method differs from that of Example 1 only in that α-amylase is not added in step (2), and the reduced mass of α-amylase is proportionally allocated to pullulanase and isoamylase, while other conditions remain unchanged.

[0045] Comparative Example 6 This comparative example provides a starch-lipid complex, which is prepared by the following method: (1) Mix corn starch and water to prepare a starch suspension with a starch content of 10%, place it in an autoclave for pressure heat treatment, first maintain at 100℃ for 15 min, then maintain at 121℃ for 45 min, and then cool down to 90℃ and maintain for 10 min to obtain starch paste. (2) The pH of the starch paste was adjusted to 4.5 using 1 M acetic acid, and then mixed with α-amylase. The α-amylase accounted for 0.5% of the dry weight of the debranched starch paste. The mixture was hydrolyzed in a water bath at 60°C for 40 min to obtain the hydrolyzed mixture. (3) Mix the enzymatic hydrolysis mixture with pullulanase and isoamylase in a mass ratio of 2:1. The total amount of the two enzymes added is 1% of the dry mass of the enzymatic hydrolysis mixture. After mixing, the mixture is subjected to debranching reaction by shaking in a water bath at 60°C for 3 h to obtain debranched starch paste. (4) The debranched starch paste and 5% of the dry weight of the debranched starch paste (lauric acid and linoleic acid in a mass ratio of 7:3) were mixed and reacted. The reaction temperature was 70℃, and the mixture was stirred in a water bath for 30 min. After the reaction, the mixture was aged and crystallized at 4℃ for 48 h, and then microwaved for 10 min at a microwave power of 600 W. After that, the mixture was dried at 105℃ for 6 h, pulverized and passed through a 100-mesh sieve to obtain the starch-lipid complex.

[0046] Comparative Example 7 This comparative example provides a starch-lipid complex, which is prepared by the following method: (1) Mix corn starch and water to prepare a starch suspension with a starch content of 10%. Adjust the pH of the starch suspension to 4.5 using 1 M acetic acid. Then mix pullulanase and isoamylase in a mass ratio of 2:1. The total amount of the two enzymes added is 1% of the dry weight of the starch paste. After mixing, debranching reaction is carried out by shaking in a water bath at 60°C for 3 h to obtain debranched starch paste. (2) Mix the debranched starch paste and α-amylase, with α-amylase accounting for 0.5% of the dry weight of the debranched starch paste, and hydrolyze in a water bath at 60°C for 40 min to obtain the hydrolysate mixture; (3) The enzymatic hydrolysate was placed in an autoclave for pressure heat treatment. First, it was maintained at 100℃ for 15 min, then at 121℃ for 45 min, and then cooled to 90℃ for 10 min to obtain starch paste. (4) The starch paste and lipids (lauric acid and linoleic acid in a mass ratio of 7:3) accounting for 5% of the dry weight of the starch paste were mixed and reacted. The reaction temperature was 70℃, and the mixture was stirred in a water bath for 30 min. After the reaction, the mixture was aged and crystallized at 4℃ for 48 h, and then microwaved for 10 min at a microwave power of 600 W. After that, the mixture was dried at 105℃ for 6 h, pulverized and passed through a 100-mesh sieve to obtain the starch-lipid complex.

[0047] Comparative Example 8 This comparative example provides a starch-lipid complex. The preparation method differs from that of Example 1 only in that step (4) is changed to: mixing the enzymatically hydrolyzed mixture with 5% of the dry weight of the mixture of lipids (lauric acid and linoleic acid in a mass ratio of 7:3) for a composite reaction. The reaction temperature is 70°C, and the mixture is stirred in a water bath for 30 min. After the reaction, the mixture is aged and crystallized at 4°C for 72 h, then dried at 105°C for 6 h, and pulverized through a 100-mesh sieve to obtain the starch-lipid complex.

[0048] Test Example 1 This test case describes the structural characterization and basic performance determination of the starch-lipid complexes of Examples 1-6 and Comparative Examples 1-8.

[0049] (1) Determination of Composite Index (CI) The starch-lipid complexes from Examples 1-6 and Comparative Examples 1-8 were used as test samples. 0.1 g (dry basis) of each sample was accurately weighed, and 4.9 mL of distilled water was added. The samples were treated at 121°C for 30 min to achieve complete gelatinization. After cooling, 10 mL of distilled water was added, and the mixture was centrifuged at 4000 r / min for 10 min. 0.5 mL of the supernatant was collected, and 15 mL of distilled water and 2 mL of iodine solution (containing 2% KI and 1% I2, w / v) were added. The absorbance was measured at 620 nm using the unadded starch sample as a blank control.

[0050] The formula for calculating the composite index is as follows: CI (%) = (A0 - A1) / A0 × 100 Where A0 is the absorbance of the control and A1 is the absorbance of the sample. The test results are shown in Table 1.

[0051] (2) Yield determination Weigh the input starch raw material (M1) and the final dried complex (M2) separately. The calculation formula is as follows: Yield (%) = M2 / M1 × 100% The test results are shown in Table 1. The results showed that the starch-lipid complex prepared by this invention has an excellent complexation index, high lipid content, and good yield. Furthermore, the step-by-step heating and cooling pressurization method used in this invention achieves better technical results than direct heating and cooling in a single step. The combined use of two lipids in this invention can also result in a higher lipid content. If the enzyme used in this invention is changed, or the reaction sequence is altered, or microwave pretreatment is omitted, both the complexation index and lipid content of the complex will decrease significantly.

[0052] Test Example 2 This test case evaluates the functional properties of the starch-lipid complexes of Examples 1-6 and Comparative Examples 1-8.

[0053] (1) Determination of resistant starch content The starch-lipid complexes from Examples 1-6 and Comparative Examples 1-8 were used as test samples. 100 mg of each sample was accurately weighed and placed in a 50 mL centrifuge tube. 4.0 mL of a pancreatin-amylase mixed enzyme solution (containing 10 mg / mL pancreatin and 3 U / mL amylase) was added, and the mixture was incubated at 160 r / min in a 37℃ water bath. At 0, 20, and 120 min, 0.1 mL of the digest was taken, and 0.9 mL of anhydrous ethanol was added to terminate the reaction. The mixture was centrifuged at 3500 g for 10 min. 0.1 mL of the supernatant was taken, and the absorbance was measured at 510 nm using the GOPOD reagent. The total starch content of the samples was determined using a total starch kit. The total starch content was calculated using the following formula: RDS (%) = (G 20 -FG)×0.9×100 / TS SDS (%) = (G 120 -G 20 ) × 0.9 × 100 / TS RS (%) = TS - RDS - SDS In the formula, FG represents the free glucose content (%) in the sample; G 20 G 120 The percentage of glucose hydrolyzed at 20 min and 120 min are respectively; TS is the total starch content in the sample (g / 100g).

[0054] The test results are shown in Table 2.

[0055] (2) Storage stability test The starch-lipid complexes of Examples 1-6 and Comparative Examples 1-8 were used as test samples. 5 g of each sample was stored in a 40℃ constant temperature drying oven. Samples were taken and measured on days 0, 14, and 28. Each time, 0.05 g of sample was accurately weighed into a 15 mL centrifuge tube, 5 mL of anhydrous ethanol was added, the mixture was vortexed, sonicated for 10 min, and centrifuged at 4000 r / min for 5 min. The supernatant was collected, and the lipid content was determined by gas chromatography. The lipid retention rate was calculated using the following formula: Lipid retention rate (%) = (Lipid content in the sample after storage / Lipid content in the initial sample) × 100% A higher lipid retention rate indicates better storage stability of the complex.

[0056] The test results are shown in Table 2. Test results show that the starch-lipid complex prepared using the method of the present invention has excellent resistant starch content and maintains good lipid retention rate after being stored at 40°C for 28 days, exhibiting excellent stability. However, the pressure heat treatment method, enzymatic hydrolysis reaction, lipid selection, and specific reaction sequence in the preparation method of the present invention have a significant impact on the resistant starch content and stability. Changing the corresponding reaction conditions will lead to a significant decrease in the technical effect.

[0057] The applicant declares that the technical solution of this invention is illustrated by the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

[0058] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0059] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for preparing starch-lipid complexes by pressure heating combined with enzymatic hydrolysis, characterized in that, The method includes: (1) Mix starch with water to obtain a starch suspension, and perform pressure heat treatment in an autoclave to obtain starch paste; (2) Mix starch paste with pullulanase and isoamylase to carry out debranching reaction to obtain debranched starch paste; (3) Mix the debranched starch paste and α-amylase to obtain an enzymatically hydrolyzed mixture; (4) The enzymatic hydrolysate and lipids are mixed and subjected to a complex reaction. After the reaction, crystallization and microwave treatment are performed to obtain the starch-lipid complex.

2. The method according to claim 1, characterized in that, The starch mentioned in step (1) includes any one or a combination of at least two of corn starch, wheat starch, and potato starch; Preferably, the starch suspension in step (1) has a mass percentage content of 8-12%; Preferably, the pressure heat treatment is a stepped heating and cooling pressure heat treatment, specifically: the first stage is maintained at 95-105℃ for 10-15 min, the second stage is maintained at 110-125℃ for 30-60 min, and the third stage is maintained at 85-95℃ for 5-15 min.

3. The method according to claim 1 or 2, characterized in that, Before mixing the starch paste with pullulanase and isoamylase in step (2), the process also includes adjusting the pH of the starch paste to 4.0-6.0 using a pH adjuster. Preferably, the pH adjuster includes acetic acid.

4. The method according to any one of claims 1-3, characterized in that, The mass ratio of pullulanase to isoamylase in step (2) is 1:(0.5-3); Preferably, the total amount of pullulanase and isoamylase added in step (2) is 0.02-1.5% of the dry weight of the starch paste; Preferably, the debranching reaction in step (2) is carried out at a temperature of 50-60°C for 0.5-8 h.

5. The method according to any one of claims 1-4, characterized in that, The α-amylase in step (3) accounts for 0.25-1.0% of the dry weight of the debranched starch paste; Preferably, the temperature of the mixing reaction in step (3) is 50-60℃ and the time is 20-90 min.

6. The method according to any one of claims 1-5, characterized in that, The lipids mentioned in step (4) include any one or a combination of at least two of the following: lauric acid, linoleic acid, glyceryl monostearate, glyceryl stearate, stearic acid, myristic acid, and palmitic acid; Preferably, the lipid in step (4) is a combination of lauric acid and linoleic acid; Preferably, the mass ratio of lauric acid to linoleic acid is (5-8):(2-5).

7. The method according to any one of claims 1-6, characterized in that, The amount of lipid added in step (4) is 0.2-5% of the dry weight of the enzymatic hydrolysate mixture; Preferably, the temperature of the composite reaction in step (4) is 60-95℃ and the time is 30-120 min; Preferably, the crystallization treatment is carried out at a temperature of 1-20°C for a time of 36-72 h; Preferably, the microwave processing power is 500-700 W and the time is 5-10 min.

8. The method according to any one of claims 1-7, characterized in that, Step (4) after microwave treatment also includes drying and pulverizing steps; Preferably, the drying temperature is 105-200℃ and the time is 2-24 h; Preferably, the mesh size of the pulverized material is 80-100 mesh.

9. The starch-lipid complex prepared by the method according to any one of claims 1-8.

10. The use of the starch-lipid complex according to claim 9 in the preparation of low glycemic index products and / or food stabilizers.

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