PREPARATION METHOD OF MODIFIED STARCH-LIPID BINARY COMPLEXES

Abstract

Preparation method of modified starch-lipid binary complexes is provided. The preparation method includes: subjecting native starch to chemical modification utilizing octenyl succinic anhydride; and preparing a starch suspension with a concentration of 7-20% by taking starch octenyl succinate and lipid as raw materials at a mass ratio of (10-200):1. The modified starch-lipid binary complexes can be efficiently prepared through an aqueous phase system. According to the preparation method, not only the complexing of starch with fatty acid or monoglyceride but also the complexing of starch with diglyceride can be effectively promoted during food processing. Compared with the traditional technologies, the starch-lipid complexes prepared based on the present disclosure are more efficient, better structured, and more potentially useful for enhancing food quality to improve human nutritional health.

Claims

1. A preparation method of modified starch-lipid binary complexes, comprising: (1) preparing a modified starch with octenyl succinic anhydride comprising taking corn starch into an aqueous ionic liquid to prepare a 10 wt% starch suspension, adjusting pH of the system to a pH of 8.0-8.5 by adding a sodium hydroxide solution with a concentration of 0.5 M, weighing octenyl succinic anhydride that accounts for 1%-9% of the mass of the starch on dry basis and adding into the starch suspension drop by drop within 2.5 h at a temperature of 25° C. to perform a modification reaction for modifying the corn starch, maintaining the modification reaction for 5 hours at a stirring rate of 200 rpm, adjusting pH of the reaction system to a pH of 6.0, centrifuging and washing the reaction mixture for 3 times, where the centrifuging is carried out for 10 minutes at a centrifugal force of 5,000 g, and the washing is carried out with distilled water and 70% ethanol alternately, then drying via vacuum at 40° C. for 12 hours to yield the modified starch with octenyl succinic anhydride, wherein the aqueous ionic liquid is prepared by mixing a 1-ethyl-3-methyl imidazole acetate ionic liquid with water at a mass ratio of 2:8; (2) preparing a modified starch-lipid suspension comprising adding the modified starch with octenyl succinic anhydride prepared in step (1) into distilled water to yield a 7-20 wt% suspension by stirring, then adding a lipid to yield the modified starch-lipid suspension by stirring, wherein a mass ratio of the lipid to the modified starch on a dry basis is 1:(10-200), and the lipid is a long-chain fatty acid or a glyceride; (3) heating the modified starch-lipid suspension obtained in step (2) in a magnetic stirring temperature control water bath for starch gelation and conducting freeze-drying and grinding, comprising 3A) in a preheating and uniform mixing stage, subjecting the modified starch-lipid suspension to preheating and stirring at a temperature of 50° C. at a stirring rate of 200 rpm for 2 min; 3B) in a heating and reaction stage, raising the temperature to 100° C. at a heating rate of 25° C./min, and carrying out a complexing reaction at a stirring rate of 260 rpm for 1 hours; 3C)in a cooling and formation stage, lowering the temperature to 25° C. at a cooling rate of 10° C./min and a stirring rate of 100 rpm to yield a gelatinized sample of a modified starch-lipid complex; and 3D) in a sample treating stage, rapidly placing the gelatinized sample in liquid nitrogen for cooling for 5 min, freeze-drying for 24 hours, grinding with a high-throughput liquid nitrogen freezing grinder with a rotor size of 6*Φ0.9 cm at a rotation speed of 10 cps for 10 min, and then sieving with a 100-mesh sieve to obtain the modified starch-lipid binary complexes.

2. The preparation method of modified starch-lipid binary complexes according to claim 1, wherein in step (2), adding the modified starch with octenyl succinic anhydride prepared in step (1) into distilled water, pre-mixing for 3 minutes and stirring at a stirring rate of 200 rpm to yield an 8 wt% suspension, then adding a lipid to yield the modified starch-lipid suspension by stirring for 2 minutes at a stirring rate of 260 rpm, wherein the mass ratio of the lipid to the modified starch on a dry basis is 1:200, 1:40, 1:20, and 1:10.

3. The preparation method of modified starch-lipid binary complexes according to claim 1, wherein the long-chain fatty acid is palmitic acid, and the glyceride is monoglyceride palmitate or diglyceride palmitate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 (A/B/C) shows X-ray diffraction patterns in Examples 1-9 and Comparative Examples 1-3, respectively.

[0024] FIG. 2 (A/B/C) shows Fourier transform infrared spectra in Examples 1-9 and Comparative Examples 1-3, respectively.

[0025] FIG. 3 (A/B/C) shows laser confocal Raman spectra in Examples 1-9 and Comparative Examples 1-3, respectively.

[0026] FIG. 4 shows laser scanning confocal staining images in Examples 1-9 and Comparative Examples 1-3, respectively.

DESCRIPTION OF THE EMBODIMENTS

[0027] The exemplary preferred embodiments of the present disclosure are described in more detail below to further illustrate the present disclosure. Although the exemplary preferred embodiments of the present disclosure are shown in the specification, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, the embodiments are provided to make the present disclosure understood more thoroughly and to make the scope of the present disclosure fully conveyed to technical persons in the field, to help the technical persons in the field to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solutions of the present disclosure.

[0028] In some embodiments, the present application provides the preparation method of modified starch-diglyceride complexes. The native starch is modified for improving the emulsifying ability of a starch molecular chain so that the complexing of the starch and a lipid (a long-chain fatty acid and a diglyceride) is promoted, and a binary complex is prepared. In particular, the preparation of a complex of the starch octenyl succinate and the diglyceride is promoted. This achieved a breakthrough in the preparation technology of starch-diglyceride complexes. The complexes prepared by the present application have better physical and chemical properties and nutritional functions, better quality, and structure, and can potentially improve the quality of food and the regulation and improvement of the nutrition and health of the human.

Example 1

[0029] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 1% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride (starch octenyl succinate).

[0030] Preparation of the modified starch-lipid suspension. The starch octenyl succinate was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare an 8 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the modified starch-lipid suspension, where a mass ratio of the lipid to the modified starch on dry basis was 1:20, and the palmitic acid (a long-chain fatty acid) was used as the lipid.

[0031] Preparation method of the binary complexes includes: 3A) in a preheating and uniform mixing stage, subjecting a modified starch-lipid suspension to preheating and stirring through a precise temperature control system at 50° C. at a stirring rate of 200 rpm for 2 min; 3B) in a heating and reaction stage, raising the temperature to 100° C. at a heating rate of 25° C./min, and carrying out a complexing reaction at a stirring rate of 260 rpm for 1 h; 3C) in a cooling and formation stage, lowering the temperature to 25° C. at a cooling rate of 10° C./min and a stirring rate of 100 rpm; and 3D) in a sample treating stage, rapidly placing an obtained gelatinized sample of a modified starch-lipid complex in liquid nitrogen for cooling for 5 min, conducting freeze-drying for 24 h, conducting grinding with a high-throughput liquid nitrogen freezing grinder (with a rotor size of 6*Φ0.9 cm) at a rotation speed of 10 cps for 10 min, and then conducting sieving with a 100-mesh sieve to obtain a binary complex of the modified starch with octenyl succinic anhydride and the palmitic acid.

Example 2

[0032] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 3% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0033] Preparation of the modified starch-lipid suspension and the added lipid are the same as those in Example 1.

[0034] Preparation method of the binary complexes is the same as that in Example 1.

Example 3

[0035] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 9% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0036] Preparation of the modified starch-lipid suspension and the added lipid are the same as those in Example 1.

[0037] Preparation method of the binary complexes is the same as that in Example 1.

Example 4

[0038] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 1% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0039] Preparation of the modified starch-lipid suspension. The starch octenyl succinate was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare an 8 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the modified starch-lipid suspension, where a mass ratio of the lipid to the modified starch on dry basis was 1:20, and the monoglyceride palmitate (a glyceride) was used as the lipid.

[0040] Preparation method of the binary complexes includes: 3A) in a preheating and uniform mixing stage, subjecting a modified starch-lipid suspension to preheating and stirring through a precise temperature control system at 50° C. at a stirring rate of 200 rpm for 2 min; 3B) in a heating and reaction stage, raising the temperature to 100° C. at a heating rate of 25° C./min, and carrying out a complexing reaction at a stirring rate of 260 rpm for 1 h; 3C) in a cooling and formation stage, lowering the temperature to 25° C. at a cooling rate of 10° C./min and a stirring rate of 100 rpm; and 3D) in a sample treating stage, rapidly placing an obtained gelatinized sample of a modified starch-lipid complex in liquid nitrogen for cooling for 5 min, conducting freeze-drying for 24 h, conducting grinding with a high-throughput liquid nitrogen freezing grinder (with a rotor size of 6*Φ0.9 cm) at a rotation speed of 10 cps for 10 min, and then conducting sieving with a 100-mesh sieve to obtain a binary complex of the modified starch with octenyl succinic anhydride and the monoglyceride palmitate.

Example 5

[0041] Preparation of the modified starch with octenyl succinic anhydride is the same as that in Example 2.

[0042] Preparation of the modified starch-lipid suspension and the added lipid are the same as those in Example 4.

[0043] Preparation method of the binary complexes is the same as that in Example 4.

Example 6

[0044] Preparation of the modified starch with octenyl succinic anhydride is the same as that in Example 3.

[0045] Preparation of the modified starch-lipid suspension and the added lipid are the same as those in Example 4.

[0046] Preparation method of the binary complexes is the same as that in Example 4.

Example 7

[0047] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 1% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0048] Preparation of the modified starch-lipid suspension. The starch octenyl succinate was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare an 8 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the modified starch-lipid suspension, where a mass ratio of the lipid to the modified starch on dry basis was 1:20, and the diglyceride palmitate (a glyceride) was used as a lipid.

[0049] Preparation method of the binary complexes includes: 3A) in a preheating and uniform mixing stage, subjecting a modified starch-lipid suspension to preheating and stirring through a precise temperature control system at 50° C. at a stirring rate of 200 rpm for 2 min; 3B) in a heating and reaction stage, raising the temperature to 100° C. at a heating rate of 25° C./min, and carrying out a complexing reaction at a stirring rate of 260 rpm for 1 h; 3C) in a cooling and formation stage, lowering the temperature to 25° C. at a cooling rate of 10° C./min and a stirring rate of 100 rpm; and 3D) in a sample treating stage, rapidly placing an obtained gelatinized sample of a modified starch-lipid complex in liquid nitrogen for cooling for 5 min, conducting freeze-drying for 24 h, conducting grinding with a high-throughput liquid nitrogen freezing grinder (with a rotor size of 6*Φ0.9 cm) at a rotation speed of 10 cps for 10 min, and then conducting sieving with a 100-mesh sieve to obtain a binary complex of the modified starch with octenyl succinic anhydride and the diglyceride palmitate.

Example 8

[0050] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 3% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0051] Preparation of the modified starch-lipid suspension and the added lipid are the same as those in Example 7.

[0052] Preparation method of the binary complexes is the same as that in Example 7.

Example 9

[0053] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 9% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0054] Preparation of the modified starch-lipid suspension and the added lipid are the same as those in Example 7.

[0055] Preparation method of the binary complexes is the same as that in Example 7.

Comparative Example 1

[0056] Native corn starch was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare an 8 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the starch-lipid suspension, where a mass ratio of the lipid to the native starch on dry basis was 1:20, and the palmitic acid (a long-chain fatty acid) was used as the lipid.

[0057] Preparation method of the binary complexes is the same as that in Example 1.

Comparative Example 2

[0058] Native corn starch was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare an 8 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the starch-lipid suspension, where a mass ratio of the lipid to the native starch on dry basis was 1:20, and the monoglyceride palmitate (a glyceride) was used as a lipid.

[0059] Preparation method of the binary complexes is the same as that in Example 4.

Comparative Example 3

[0060] Native corn starch was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare an 8 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the starch-lipid suspension, where a mass ratio of the lipid to the native starch on dry basis was 1:20, and the diglyceride palmitate (a glyceride) was used as a lipid.

[0061] Preparation method of the binary complexes is the same as that in Example 7.

[0062] Relevant test results of substances prepared in all the examples and comparative examples by the method of the present disclosure are as follows.

[0063] The degree of substitution (DS) of starch modified by different percentages (1%, 3%, and 9%) of octenyl succinic anhydride is determined.

[0064] 2.0 g of a sample was weighed, put into a 250 ml beaker, moistened with 10 ml of isopropanol, and stirred for 10 min. 15 mL of a 2.5 mol /L hydrochloric-isopropanol solution was added and stirred magnetically for 30 min. Then, 50 mL of a 90% isopropanol solution was added and stirred continuously for 10 min. The sample was transferred to a Buchner funnel and washed with 90% isopropanol until no Cl.sup.- was found (tested with 0.1 mol/L silver nitrate). Then, the sample was transferred to a 500 mL beaker, deionized water was added to reach 300 mL, and treatment was conducted in a boiling water bath for 20 min. 2 drops of a phenolphthalein reagent were dropped, and a 0.1 mol/L sodium hydroxide solution was added for titration under heating until the solution was turned into pink and the color was not changed within 30 s. The following formula is used for calculation: degree of substitution (DS) =0.1624*N/(1-0.21*N), where N refers to the mass of the 0.1 mol/L sodium hydroxide standard solution consumed (mmol).

[0065] The emulsifying ability of modified starch is determined.

[0066] A starch sample (1.5%, w/w) suspension was heated in a boiling water bath and stirred for 20 min. Soybean oil (which accounts for 5% of the mass of the starch suspension) was added to the starch suspension in a high-speed homogenizer (Ultra-Turrax T18) to prepare an oil-in-water (O/W) emulsion. Homogenization was conducted at 12,000 rpm at room temperature for a total of 4 times with 1.5 min for each time. Then, 50 .Math.L of an emulsion solution was evenly mixed with 5 mL of 0.1% sodium dodecyl sulfate to form a fine emulsion solution. The absorbance (A.sub.0) at 500 nm was measured with 0.1% sodium dodecyl sulfate as a blank control to determine the emulsifying activity. After an emulsion sample was placed for 20 min, the absorbance (A.sub.20) was measured again at 500 nm. The emulsifying stability is calculated according to the following formula: emulsifying stability (min)=20*A.sub.0/ (A.sub.0-A.sub.20).

[0067] The above results are shown in Table 1. With the increase of the added percentage of the octenyl succinic anhydride (1%-9%), the degree of substitution of an octenyl succinic anhydride group in the modified starch is gradually increased from 0.0071 to 0.0489, and the highest emulsifying activity and emulsifying ability reach 2.09 min and 1213.5 min, respectively, which are significantly improved in comparison with native starch.

TABLE-US-00001 Degree of substitution, emulsifying activity, and emulsifying ability of modified starch Name Degree of substitution Emulsifying activity Emulsifying stability (min) Native starch / 0.43 ± 0.02e 126.6 ± 9.5e 1%-Modified starch 0.0071 ± 0.0001c 0.94 ± 0.07d 207.6 ± 4.2d 3%-Modified starch 0.0210 ± 0.0003b 1.43 ± 0.10b 676.3 ± 8.2b 9%-Modified starch 0.0489 ± 0.0001a 2.09 ± 0.09a 1213.5 ± 80.7a Note: The data in the table are represented as mean ± standard deviation; the same suffix letter indicates no significant difference and different letters indicate significant differences (p < 0.05); and “/” indicates that no data is detected.

[0068] The complexing index of a complex sample is determined.

[0069] A starch-lipid complex (0.4 g) was weighed and added into a 50 mL centrifuge tube, and then distilled water was added to reach a total weight of 5.0 g. After vortex treatment was conducted, a uniform suspension was heated in a boiling water bath at a magnetic stirring rate of 200 rpm until complete gelatinization of starch. After cooling was conducted to room temperature, 25 mL of distilled water was added, and uniform vortex mixing was conducted for 2 min before centrifugation (3,000 g, 15 min). 600 .Math.L of supernatant was taken out and transferred to a test tube, and 15 mL of distilled water and 2 mL of an iodine solution (prepared by adding 2.0% of KI and 1.3% of I.sub.2 in distilled water) were added. The ultraviolet absorbance was measured at 690 nm. The native corn starch treated with the above method was used as a control. The complexing index is calculated according to the following formula: complexing index

[00001]$\left(\text{\%}\right)\text{=100*}\left({\text{absorbance}}_{\text{control}}{\text{-absorbance}}_{\text{starch-lipid}}\right)/{\text{absorbance}}_{\text{control}}\text{.}$

[0070] The above results are shown in Table 2. In the comparative examples, after the native starch is subjected to a complexing reaction with palmitic acid, monoglyceride palmitate, and diglyceride palmitate separately, the complexing interaction between the native starch and the monoglyceride palmitate (in Comparative Example 2) is higher than that between the native starch and the palmitic acid (in Comparative Example 1), and a complex of the native starch and the diglyceride palmitate (in Comparative Example 3) is not produced. After the native starch is modified by the octenyl succinic anhydride, the complexing effect of the modified starch and various lipids is enhanced. Compared with Comparative Example 1 and Comparative Example 3, the complexing interaction in Examples 1-3 and Examples 7-9 is significantly enhanced, the complexing index is significantly increased, and the complexing index in Comparative Example 1 or Comparative Example 3 is increased from 21.6% or 8.6% to 93.3% or 93.2%. Moreover, with the increase of the modification degree (degree of substitution) of the octenyl succinic anhydride, the effect of improving the complexing index of the modified starch and a long-chain fatty acid or a glyceride, especially the efficiency of complexing interaction with the diglyceride palmitate (in Examples7-9), is better.

TABLE-US-00002 Complexing index of starch-lipid binary complexes (%) Name Complexing index (%) Palmitic acid Monoglyceride palmitate Diglyceride palmitate Native starch Comparative Example 1 Comparative Example 2 Comparative Example 3 21.6 ± 0.9d 89.1 ± 0.8d 8.6 ± 0.7d 1%-Modified starch Example 1 Example 4 Example 7 79.6 ± 0.4c 91.2 ± 0.3c 80.3 ± 0.5c 3%-Modified starch Example 2 Example 5 Example 8 91.4 ± 0.2b 93.0 ± 0.4b 90.5 ± 0.6b 9%-Modified starch Example 3 Example 6 Example 9 93.3 ± 0.3a 95.1 ± 0.3a 93.2 ± 0.4a Note: The data in the table are represented as mean ± standard deviation, and the same suffix letter indicates no significant difference and different letters indicate significant differences (p < 0.05).

[0071] The crystal structure of a native starch-lipid complex and a modified starch-lipid complex is detected by using an X-ray diffractometry (D8 Advance) of Bruker in Germany (as shown in FIG. 1). According to test results, it is shown that compared with binary complexes prepared from the native starch in Comparative Examples 1-3, binary complexes prepared from the starch octenyl succinate in Examples 1-3, Examples 4-6, and Examples 7-9 have stronger characteristic diffraction peaks (12.9° and 19.8°) of V-type crystallites. It is indicated that the binary complexes prepared from the modified starch in the examples consist of V-type crystalline complexes with stable structures and large numbers, and with the improvement of the emulsifying activity of the starch modified by octenyl succinic anhydride, the structure and number of the binary complexes are also gradually stabilized and improved.

[0072] The short-range molecular ordered structure of a native starch-lipid complex and a modified starch-lipid complex is detected by using a Fourier transform infrared spectrometer (IS50) of Bruker in Germany (as shown in FIG. 2 and Table 3). According to test results, it is shown that compared with the binary complexes prepared from the native starch in Comparative Examples 1-3, the binary complexes prepared from the starch octenyl succinate in Examples 1-3, Examples 4-6, and Examples 7-9 have better short-range molecular order, and with the increase of the degree of substitution of the starch modified by octenyl succinic anhydride, the short-range molecular order of the binary complexes is significantly improved. The IR ratio of absorbance at 1047/1022 cm.sup.-1 of the binary complexes increased, indicating that the short-range structural order of the binary complexes of the present application was significantly improved.

TABLE-US-00003 IR ratio of absorbances at 1047/1022 cm.sup.-1 of the starch-lipid binary complexes Name IR ratio of absorbances at 1047/1022 cm.sup.-1 Palmitic acid Monoglyceride palmitate Diglyceride palmitate Native starch Comparative Example 1 Comparative Example 2 Comparative Example 3 0.50 ± 0.01d 0.65 ± 0.00d 0.41 ± 0.01d 1%-Modified starch Example 1 Example 4 Example 7 0.62 ± 0.01c 0.67 ± 0.01c 0.59 ± 0.02c 3%-Modified starch Example 2 Example 5 Example 8 0.67 ± 0.00b 0.69 ± 0.01b 0.62 ± 0.01b 9%-Modified starch Example 3 Example 6 Example 9 0.69 ± 0.02a 0.72 ± 0.01a 0.67 ± 0.01a Note: The data in the table are represented as mean±standard deviation, and the same suffix letter indicates no significant difference and different letters indicate significant differences (p < 0.05).

[0073] The short-range ordered structure of a native starch-lipid complex and a modified starch-lipid complex is detected by using a laser confocal Raman imaging spectrometer (Renishaw Invia) of Renishaw in Britain (as shown in FIG. 3 and Table 4). According to test results, it is shown that compared with the binary complexes prepared from the native starch in Comparative Examples 1-3, the binary complexes prepared from the starch octenyl succinate in Examples 1-3, Examples 4-6, and Examples 7-9 have better short-range molecular order, and with the increase of the degree of substitution of the starch modified by octenyl succinic anhydride, the short-range molecular order of the binary complexes is significantly improved. The full width at half-maximum at 480 cm.sup.-1 of the complexes decreased, indicating that the short-range structure order of the binary complexes of the present application was significantly improved.

TABLE-US-00004 Full width at half-maximum at 480 cm.sup.-1 of the starch-lipid binary complexes Name Full width at half-maximum at 480 cm.sup.-.sup.1 Palmitic acid Monoglyceride palmitate Diglyceride palmitate Native starch Comparative Example 1 Comparative Example 2 Comparative Example 3 20.53 ± 0.29d 17.64 ± 0.29d 23.95 ± 0.74d 1%-Modified starch Example 1 Example 4 Example 7 18.56 ± 0.25c 16.67 ± 0.16c 19.07 ± 0.06c 3%-Modified starch Example 2 Example 5 Example 8 17.64 ± 0.21b 15.90 ± 0.08b 18.34 ± 0.19b 9%-Modified starch Example 3 Example 6 Example 9 16.08 ± 0.11a 15.58 ± 0.28a 17.38 ± 0.06a Note: The data in the table are represented as mean ± standard deviation, and the same suffix letter indicates no significant difference and different letters indicate significant differences (p < 0.05).

[0074] The morphology and structure of actual samples of a native starch-lipid complex and a modified starch-lipid complex are analyzed by using a laser scanning confocal microscope (TCSSP5) of Leica in Germany (as shown in FIG. 4). According to test results, it is shown that (a starch structure shows green fluorescence, a lipid structure shows red fluorescence and a complex structure shows yellow fluorescence) the samples of the binary complexes prepared from the native starch in Comparative Examples 1-3 show poor aggregates or mixtures (as shown by green fluorescence) in actual morphology, and although the sample in Comparative Example 2 has a complex with a rod-shaped structure, the number of the complexes is relatively small. However, the samples of the binary complexes prepared from the starch octenyl succinate in Examples 1-3, Examples 4-6, and Examples 7-9 show a larger number of complexes with a real rod-shaped morphology and structure (a rod-like structure as shown by yellow fluorescence), and all the samples in Example 3, Example 6, and Example 9 have more binary complexes. A binary complex of the starch octenyl succinate and a lipid is prepared by the method of the present disclosure for the first time, and the real morphology and structure are photographed.

[0075] Thermal properties of a native starch-lipid complex and a modified starch-lipid complex are analyzed by using a high-sensitivity differential scanning calorimeter (200 F3) of Netzsch in Germany. The above results are shown in Table 5. According to the analysis of test results, it is shown that a binary complex of starch octenyl succinate and a lipid has a better melting temperature (T.sub.pII) and a larger enthalpy value (ΔH). Compared with the complexes prepared from the native starch (in Comparative Examples 1-3), the complexes in Examples 1-3, Examples 4-6, and Examples 7-9 have excellent thermal stability and more ordered crystal structures.

Example 10

[0076] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 1% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0077] Preparation of the modified starch-lipid suspension. The starch octenyl succinate was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare a 7 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the modified starch-lipid suspension, where a mass ratio of the lipid to the modified starch on dry basis was 1:10, and the diglyceride palmitate (a glyceride) was used as the lipid.

[0078] Preparation method of the binary complexes is the same as that in Example 4.

Example 11

[0079] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 1% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0080] Preparation of the modified starch-lipid suspension. The starch octenyl succinate was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare a 20 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the modified starch-lipid suspension, where a mass ratio of the lipid to the modified starch on dry basis was 1:40, and the diglyceride palmitate (a glyceride) was used as the lipid.

[0081] Preparation method of the binary complexes is the same as that in Example 4.

Example 12

[0082] Preparation of the modified starch with octenyl succinic anhydride. Corn starch was prepared into a 10 wt% starch suspension with an aqueous ionic liquid; then a sodium hydroxide solution with a concentration of 0.5 M was added for adjusting the pH value of the system to 8.0-8.5; octenyl succinic anhydride that accounts for 1% of the mass of the starch on dry basis was weighed and added drop by drop into the system within 2.5 h for modifying the starch at a temperature of 25° C.; the modification reaction was carried out at a stirring rate of 200 rpm for 5 h; after the reaction was completed, the pH value of the system was adjusted to 6.0; centrifuging and washing were conducted to the reaction mixture for 3 times; where every time, the centrifuging was conducted for 10 min at a centrifugal force of 5,000 g; the washing was conducted with deionized water and 70% ethanol alternately; and then drying was conducted in a vacuum drying oven at 40° C. for 12 h to obtain the modified starch with octenyl succinic anhydride.

[0083] Preparation of the modified starch-lipid suspension. The starch octenyl succinate was premixed with deionized water at a stirring rate of 200 rpm for 3 min to prepare an 8 wt% starch suspension, and then a lipid was added for stirring at a rate of 260 rpm for 2 min to yield the modified starch-lipid suspension, where a mass ratio of the lipid to the modified starch on dry basis was 1:200, and the diglyceride palmitate (a glyceride) was used as the lipid.

[0084] Preparation method of the binary complexes is the same as that in Example 4.

[0085] After detection, various indexes of the binary complexes prepared in the above three examples indicate that the binary complexes of examples 10-12 are better than those prepared by complexing with the common starch. Moreover, the preparation method of the present disclosure is simple and easy to operate.

[0086] Based on the analysis of the above test data and results, the present disclosure provides the preparation method of modified starch-lipid binary complexes with high efficiency. Compared with traditional methods for preparing complexes, the method of the present application has the advantage that the technical barrier of complexing interaction between starch and a diglyceride is broken through achieving the complexing without adding any exogenous additives, and greatly improves the complexing efficiency of the starch and a lipid. The modified starch-lipid complexes prepared by the present application have a better V-type crystalline structure, short-range structure order, and thermal stability than a native starch-lipid complex, and can potentially improve the quality of food and the regulation and improvement of the nutrition and health of the human.

[0087] The basic principle, main characteristics, and advantages of the present disclosure are shown and described above. It should be understood by technical persons in the industry that the present disclosure is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only intended to illustrate the principle of the present disclosure. Various changes and improvements to the present disclosure may also be made without departing from the spirit and scope of the present disclosure, and all the changes and improvements shall fall within the protection scope of the present disclosure as required. The protection scope of the present disclosure as required is defined by the attached claims and equivalents thereof.

[0088] All structural changes made from the concept of the present disclosure without creative effort fall within the protection scope of the present disclosure.

TABLE-US-00005 Thermal properties of starch octenyl succinate and starch-lipid binary complexes Name T.sub.oI(°C) T.sub.pI(°C) T.sub.cI(°C) ΔH.sub.I(J/g) T.sub.oII(°C) T.sub.pII(°C) T.sub.cII(°C) ΔH.sub.II(J/g) ΔH(J/g) Comparative Example 1 97.7 ± 0.2a 105.4 ± 0.1a 110.9 ± 0.4a 0.5 ± 0.1d / / / / 0.5 ± 0.1d Example 1 95.2 ± 0.1d 99.5 ± 0.2d 104.4 ± 0.2c 1.2 ± 0.0c 107.2 ± 0.1c 111.1 ± 0.1c 120.5 ± 0.1c 1.7 ± 0.1b 2.9 ± 0.1c Example 2 95.8 ± 0.3c 101.7 ± 0.1c 106.5 ± 0.0b 4.6 ± 0.1b 110.8 ± 0.2b 116.6 ± 0.1b 123.4 ± 0.2b 3.2 ± 0.1a 7.8 ± 0.1b Example 3 96.8 ± 0.1b 104.6 ± 0.6b 107.2 ± 0.1b 5.0 ± 0.3a 114.3 ± 0.1a 119.0 ± 0.1a 125.2 ± 0.4a 3.3 ± 0.2a 8.3 ± 0.2a Comparative Example 2 94.3 ± 0.1a 97.8 ± 0.1a 103.6 ± 0.5a 5.3 ± 0.1a / / / / 5.3 ± 0.1d Example 4 91.4 ± 0.0b 97.0 ± 0.0b 101.9 ± 0.1b 5.0 ± 0.0b 109.3 ± 0.1b 114.6 ± 0.2a 116.5 ± 0.2c 1.5 ± 0.1b 6.5 ± 0.1c Example 5 89.8 ± 0.0b 94.6 ± 0.3c 98.7 ± 0.2c 3.8 ± 0.1c 103.4 ± 0.3c 110.8 ± 0.0c 118.4 ± 0.1b 4.7 ± 0.1a 8.5 ± 0.0b Example 6 83.3 ± 0.1d 92.8 ± 0.1d 98.3 ± 0.1c 5.1 ± 0.1b 111.0 ± 0.1a 112.6 ± 0.1b 120.6 ± 0.3a 4.9 ± 0.2a 10.0 ± 0.2a Comparative Example 3 / / / / / / / / / Example 7 95.1 ± 0.1a 99.9 ± 0.1a 107.8 ± 0.1a 3.3 ± 0.1a 109.6 ± 0.3a 113.8 ± 0.1a 116.3 ± 0.4b 1.6 ± 0.2c 4.9 ± 0.1c Example 8 94.1 ± 0.1b 99.6 ± 0.1b 107.3 ± 0.1b 2.9 ± 0.1b 108.3 ± 0.2b 112.6 ± 0.1b 116.8 ± 0.5b 3.3 ± 0.1b 6.2 ± 0.1b Example 9 93.8 ± 0.0c 97.5 ± 0.1c 101.2 ± 0.1c 0.3 ± 0.1c 107.7 ± 0.1b 113.5 ± 0.1a 118.0 ± 0.1a 7.4 ± 0.1a 7.7 ± 0.1a Note: The data in the table are represented as mean ± standard deviation; the same suffix letter indicates no significant difference and different letters indicate significant differences (p < 0.05); and “/” indicates that no data is detected.