Spaceflight purple corn citric acid esterified starch as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of starch modification, and particularly relates to spaceflight purple corn citric acid esterified starch as well as a preparation method and application thereof. The preparation method comprises the following steps: adding space purple corn starch subjected to heat-moisture treatment into a citric acid solution, uniformly stirring, adding alkali liquor to adjust the pH value, standing, drying, grinding, heating for reaction, washing a product after the reaction, and finally drying, grinding and sieving to obtain the space purple corn citric acid esterified starch. The prepared spaceflight purple corn citric acid esterified starch has a remarkable improvement effect on application in the fields of intestinal flora regulation, cardia-cerebrovascular diseases, immunity improvement, liver injury, fat accumulation and the like, meanwhile, the spaceflight purple corn starch is used as a raw material for preparation, the preparation cost is reduced, and the production cost is reduced. And the spaceflight purple corn starch is subjected to high-quality utilization, so that the additional value of the starch is improved, and the preparation method is simple and easy to implement.

Description

Technical Field

[0001] The invention belongs to the technical field of starch modification, and in particular relates to a space purple corn citric acid esterified starch and a preparation method and application thereof. Background Art

[0002] Citrate starch is obtained by esterification of starch and citric acid at a certain temperature and pH value. During esterification, citric acid also acts as a cross-linking agent. Therefore, after the starch hydroxyl groups are replaced by citric anhydride groups, the starch granules can be prevented from swelling and gelatinization during heating, and have the function of resisting enzyme degradation. This shows that after the starch molecule hydroxyl groups are replaced by citric acid carboxyl groups, the substituted groups make the overall structure of the starch hinder the attack of amylase and make the adjacent glycosidic bonds resist enzyme hydrolysis. Since citric acid is a non-toxic food additive that is nutritionally harmless, the citrate starch produced by using it as an esterifying agent and cross-linking agent can not only be safely used in different food systems, but also can be used to evaluate the quality of the final product, and can also play a role in increasing dietary fiber in food, and has a high application value.

[0003] Citrate starch is a starch derivative produced by the esterification reaction between citric anhydride and glucose hydroxyl groups in starch. The occurrence of esterification causes citric acid acyl groups to be connected to the starch molecular chain. After esterification with starch hydroxyl groups, citric acid acyl groups and starch molecules are linked together by covalent bonds, which enhances the intermolecular forces of starch and forms a huge spatial network structure. Even under high temperature conditions, the high bond energy of covalent bonds still connects starch molecules together, slows down the molecular movement rate, and it is difficult for water molecules to enter the starch molecules to form hydrogen bonds, resulting in an inhibitory effect on swelling. With the increase of the degree of esterification, the closer the connection between starch molecules, the stronger the ability to inhibit swelling. When it reaches a certain level, within 100°C, water molecules still cannot intervene between starch molecules, resulting in a non-gelatinization phenomenon.

[0004] Klaushofer et al. produced citrate starch with high freeze-thaw stability by dry method. Wepner et al. extracted 50.8% resistant starch from ordinary corn starch. Narkrugsa et al. produced citrate starch by steaming and extrusion. Yeo found through experiments that cross-linked resistant starch is not very thermally stable.

[0005] The Chinese patent application with patent application number: 201910827858.8 discloses a citrate starch and a preparation method thereof, wherein the preparation method of the citrate starch comprises the following steps: mixing starch and citric acid, adding deionized water and an alkaline catalyst to blend evenly, sealing and placing, and then putting into a subcritical extrusion device, and drying, crushing, sieving, and washing with alcohol to remove impurities to obtain a citrate starch with a degree of substitution ≥ 0.01. The invention uses subcritical water extrusion to prepare citrate starch with a degree of substitution of 0.01, and the obtained citrate starch has the defect of low esterified starch content.

[0006] The invention adopts innovative new aerospace purple corn starch as raw material. The starch of aerospace purple corn is different from ordinary starch and has the characteristics of long straight chain, short branch chain, large molecular weight and the like. It is an ideal raw material for preparing citric acid esterified starch. The shortcomings of the prior art can be overcome through raw material innovation and process optimization. A wet heat process is adopted and the reaction conditions are optimized. By creating suitable self-loading reaction conditions, citric acid ester starch with high substitution degree and strong thermal stability is prepared. Summary of the invention

[0007] Based on the above technical background, the main purpose of the present invention is to provide a method for high-quality utilization of an innovative raw material, aerospace purple corn starch. By optimizing the preparation method of citric acid esterified starch, citric acid ester starch with a high degree of substitution and strong thermal stability is prepared, and its application field is expanded.

[0008] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0009] The first aspect of the present invention is to provide a method for preparing aerospace purple corn citric acid esterified starch, the preparation method comprising the following steps:

[0010] Step 1, subjecting the aerospace purple corn starch to wet heat treatment, then adding it to the citric acid solution, stirring evenly, adding alkali solution to adjust the pH, and standing;

[0011] Step 2, after the self-assembly reaction is completed, the product is ground and then heated to react. After the reaction is terminated, the product after the reaction is washed, and finally dried, ground, and sieved to obtain the aerospace purple corn citrate esterified starch with a degree of substitution greater than 1.

[0012] Preferably, in step 1,

[0013] The wet heat treatment comprises: drying the aerospace purple corn starch, adjusting the moisture content of the aerospace purple corn starch to 10-40%, storing it at 20-30° C. for 10-15 hours, then heating it at 80-110° C. for 8-16 hours, cooling it and drying it to obtain the aerospace purple corn starch after wet heat treatment;

[0014] The aerospace purple corn starch treated with wet heat is added into a citric acid solution with a mass fraction of 40 to 70%, and the added amount of the citric acid is 10 to 60% of the added mass of the aerospace purple corn starch.

[0015] Preferably, in step 1,

[0016] NaOH solution was added to adjust the pH of the suspension to 1-3, and then the suspension was allowed to stand at 20-30°C to react for 15-20 hours.

[0017] Preferably, in step 2,

[0018] After the self-assembly reaction is allowed to stand, the mixture is dried at 60-110° C. until the moisture content is 5%-10%.

[0019] Preferably, in step 2,

[0020] After grinding, the temperature is raised to 80-150° C. and reacted for 3-16 hours.

[0021] Preferably, in step 2,

[0022] Water is added to the reaction product for washing, and the washed reaction product is dried at 60-110° C. to a moisture content of 5%-10%, and then ground, and passed through an 80-mesh sieve after grinding.

[0023] The second aspect of the present invention is to provide an aerospace purple corn citrate esterified starch having a degree of substitution greater than 1, which is prepared according to the method for preparing the aerospace purple corn citrate esterified starch described in the first aspect of the present invention.

[0024] The third aspect of the present invention is to provide an application of the aerospace purple corn citrate esterified starch described in the second aspect of the present invention in the fields of intestinal flora regulation, cardiovascular and cerebrovascular diseases, improving immunity, liver damage and fat accumulation.

[0025] The beneficial effects of the present invention are:

[0026] (1) The preparation method of the space purple corn citric acid esterified starch of the present invention is simple, and the space purple corn starch is used as a raw material for preparation, which not only reduces the preparation cost, but also makes high-quality use of the space purple corn starch, provides a suitable self-loading reaction condition, and the preparation process is green and environmentally friendly;

[0027] The invention can effectively improve the starch content and thermal stability of the aerospace purple corn citric acid esterified starch by subjecting the aerospace purple corn starch to a wet heat treatment.

[0028] (2) The aerospace purple corn citric acid esterified starch prepared by the preparation method can increase the content of TC, TG, and LDL-C in serum, improve the content of TC, TG, LDL-C, and HDL-C in serum, and has a good improvement effect on blood lipid indicators. At the same time, the aerospace purple corn citric acid esterified starch can increase the abundance of Bacteroidetes in the intestinal flora, reduce the abundance of Firmicutes, improve the intestinal flora, exert the comprehensive regulatory effect of the liver-gut axis, the immune-gut axis, and the heart-gut axis, enhance immunity, improve the formation and accumulation of vascular fat, and reduce the incidence of cardiovascular and cerebrovascular diseases.

[0029] (3) The aerospace purple corn citrate starch can significantly improve hyperlipidemia liver fatty lesions, regularly rearrange liver cells, and significantly improve liver damage and fat accumulation, indicating that the aerospace purple corn citrate starch prepared by the preparation method of the present invention has good application prospects in the field of improving liver damage and fat accumulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The TC test results of the control group, model group, simvastatin group and RS4 group in Experimental Example 1 are shown;

[0031] Figure 2 The TG test results of the control group, model group, simvastatin group and RS4 group in Experimental Example 1 are shown;

[0032] Figure 3 The LDL-C test results of the control group, model group, simvastatin group and RS4 group in Experimental Example 1 are shown;

[0033] Figure 4 The HDL-C test results of the control group, model group, simvastatin group and RS4 group in Experimental Example 1 are shown;

[0034] Figure 5 The test results of intestinal flora species in the feces of mice in the control group, model group, simvastatin group and RS4 group in Experimental Example 1 are shown.

[0035] Figure 6 Photographs of liver HE staining of the control group, model group, simvastatin group, and RS4 group in Experimental Example 1 are shown. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below, and the characteristics and advantages of the present invention will become clearer and more distinct with the description.

[0037] The first aspect of the present invention is to provide a method for preparing aerospace purple corn citric acid esterified starch, the preparation method comprising the following steps:

[0038] Step 1: subjecting the aerospace purple corn starch to wet heat treatment, then adding it to the citric acid solution, stirring evenly, adding alkali solution to adjust the pH, and allowing it to stand for self-packaging;

[0039] Step 2: After self-assembly, grind and stir, then heat and react. After the reaction is terminated, wash, dry, grind and sieve to obtain aerospace purple corn citric acid esterified starch.

[0040] The above steps are described in detail below.

[0041] In step 1, the wet heat treatment includes: drying the aerospace purple corn starch, adjusting the moisture content of the aerospace purple corn starch to 10-40%, storing it at 20-30° C. for 10-15 hours, then heating it at a temperature of 80-110° C. for 8-16 hours, cooling it and drying it to obtain the aerospace purple corn starch after wet heat treatment.

[0042] Preferably, the wet heat treatment comprises: drying the aerospace purple corn starch, adjusting the moisture content of the aerospace purple corn starch to 10-40%, storing it at 25°C for 12 hours, then heating it at 90°C for 12 hours, cooling it and drying it to obtain the aerospace purple corn starch after wet heat treatment.

[0043] Add the aerospace purple corn starch after wet heat treatment into a citric acid solution with a mass fraction of 40-70%, and the amount of citric acid added is 10-60% of the mass of the aerospace purple corn starch. After stirring evenly, add NaOH solution to adjust the suspension to a pH of 1-3, and then let it stand at 20-30°C for 15-20 hours.

[0044] Preferably, the aerospace purple corn starch after wet heat treatment is added to a 50% by mass citric acid solution, wherein the amount of citric acid added is 50% of the mass of the aerospace purple corn starch added. After stirring evenly, a 10M NaOH solution is added to adjust the pH of the suspension to 1-3, and then the suspension is allowed to stand at 25°C for 17 hours.

[0045] The citric acid used in the present invention is a non-toxic food additive and can enhance the human body's intake of organic acids.

[0046] In step 2, after standing, the mixture is dried at 40-60° C. for 10-15 hours until the moisture content of the suspension is 5%-10%, the dried mixture is ground, and then reacted at 80-150° C. for 20-25 hours. After the reaction, water is added to the reaction product for washing to remove unreacted citric acid, and the washed reaction product is dried at 40-60° C. for 20-25 hours, then ground, and passed through an 80-mesh sieve after grinding to obtain aerospace purple corn citrate esterified starch.

[0047] Preferably, after standing, the mixture is dried at 50°C for 12 hours until the moisture content of the suspension is 5% to 10%, the dried mixture is ground, and then reacted at 130°C for 22 hours. After the reaction, distilled water is added to the reaction product for washing to remove unreacted citric acid, and the washed reaction product is dried at 50°C for 24 hours, followed by grinding, and passed through an 80-mesh sieve to obtain aerospace purple corn citrate esterified starch.

[0048] The second aspect of the present invention is to provide a space purple corn citrate esterified starch prepared according to the method for preparing a space purple corn citrate esterified starch according to the first aspect of the present invention.

[0049] The third aspect of the present invention is to provide an application of the second aspect of the present invention, which exerts the comprehensive regulatory effects of aerospace purple corn citrate starch on regulating the liver-gut axis, immune-gut axis, and heart-gut axis, enhances immunity, improves vascular fat formation and accumulation, and reduces the incidence of cardiovascular and cerebrovascular diseases.

[0050] Example

[0051] The present invention is further described below by means of specific examples. These embodiments are only intended to illustrate the present invention but are not intended to limit the scope of the present invention.

[0052] Example 1

[0053] The aerospace purple corn starch was dried, and the moisture content of the aerospace purple corn starch was adjusted to 10-40%, and then stored at 25°C for 12 hours, and then heated at 90°C for 12 hours, cooled and dried to obtain the aerospace purple corn starch after wet heat treatment, and the aerospace purple corn starch after wet heat treatment was added to a citric acid solution with a mass fraction of 50%, wherein the amount of citric acid was 40% of the dry weight of the starch. After stirring evenly, the suspension was adjusted to pH 1-3 with a 10M NaOH solution, and then transferred to a stainless steel tray and placed at 25°C for 16 hours. Then it was placed in an oven and dried at 50°C for 12 hours until the moisture content of the suspension was 5%-10%. The mixture was ground and reacted in an air oven at a temperature of 130°C for 22 hours. After the reaction was completed, it was taken out, and the dry mixture was washed with 3L distilled water to remove the unreacted citric acid. The washed starch was dried at 50°C for 24 hours, and finally ground into powder with a grinder, and passed through an 80-mesh sieve to obtain the aerospace purple corn citric acid esterified starch.

[0054] Example 2

[0055] The preparation of aerospace purple corn citric acid esterified starch was carried out in a manner similar to Example 1, except that the amount of citric acid used was 10% of the dry weight of the starch.

[0056] Example 3

[0057] The preparation of aerospace purple corn citric acid esterified starch was carried out in a manner similar to Example 1, except that the amount of citric acid used was 20% of the dry weight of the starch.

[0058] Example 4

[0059] The preparation of aerospace purple corn citric acid esterified starch was carried out in a similar manner to Example 1, except that the amount of citric acid used was 30% of the dry weight of the starch.

[0060] Example 5

[0061] The preparation of aerospace purple corn citric acid esterified starch was carried out in a manner similar to Example 1, except that the amount of citric acid used was 50% of the dry weight of the starch.

[0062] Example 6

[0063] The preparation of aerospace purple corn citric acid esterified starch was carried out in a manner similar to Example 1, except that the amount of citric acid used was 60% of the dry weight of the starch.

[0064] Example 7

[0065] The aerospace purple corn starch is dried, and the moisture content of the aerospace purple corn starch is adjusted to 40%. Then, it is stored at 25°C for 12 hours, then heated at 100°C for 12 hours, cooled and dried to obtain the aerospace purple corn starch after wet heat treatment. The aerospace purple corn starch after wet heat treatment is added to a citric acid solution with a mass fraction of 40%, wherein the amount of citric acid is 40% of the dry weight of the starch. After stirring evenly, the suspension is adjusted to pH 1-3 with a 10M NaOH solution, and then transferred to a stainless steel tray and placed at 20°C for 20 hours. Then it is placed in an oven and dried at 40°C for 15 hours until the moisture content is 5%-10%. The mixture is ground and reacted in an air oven at a temperature of 80°C for 25 hours. After the reaction is completed, it is taken out, and the dry mixture is washed with 3L distilled water to remove the unreacted citric acid. The washed starch is dried at 40°C for 25 hours, and finally ground into powder with a grinder, and passed through an 80-mesh sieve to obtain the aerospace purple corn citric acid esterified starch.

[0066] Example 8

[0067] The aerospace purple corn starch was dried, and the moisture content of the aerospace purple corn starch was adjusted to 10%, and then stored at 25°C for 12h, then heated at 100°C for 12h, cooled and dried to obtain the aerospace purple corn starch after wet heat treatment. The aerospace purple corn starch after wet heat treatment was added to a citric acid solution with a mass fraction of 70%, wherein the amount of citric acid was 40% of the dry weight of the starch. After stirring evenly, the suspension was adjusted to pH 1-3 with a 10M NaOH solution, and then transferred to a stainless steel tray and placed at 30°C for 15 hours. Then it was placed in an oven and dried at 60°C for 10 hours until the moisture content was 5%-10%. The mixture was ground and reacted in an air oven at a temperature of 150°C for 20 hours. After the reaction was completed, it was taken out, and the dry mixture was washed with 3L distilled water to remove the unreacted citric acid. The washed starch was dried at 60°C for 20 hours, and finally ground into powder with a grinder, and passed through an 80-mesh sieve to obtain the aerospace purple corn citric acid esterified starch.

[0068] Experimental example

[0069] Experimental Example 1 Animal Experiment

[0070] 40 SD rats were selected and divided into a control group, a model group, a simvastatin group and an RS4 group, with an average of 10 rats in each group. The model was established by feeding with a high-fat diet: the specific operation was that the control group was fed with ordinary feed all the time, and the other three groups were fed with a high-fat diet. After four weeks of feeding, a hyperlipidemia model was formed. Then the RS4 group and the simvastatin group were treated by gavage for 4 weeks. The RS4 group was gavaged with the aerospace purple corn citrate starch prepared in Example 1, and the simvastatin group was gavaged with simvastatin. Then the animals were killed, and serum was taken to determine the four blood lipids in the serum (TC, TG, LDL-C, HDL-C), the liver was stained with HE, and the types of intestinal flora in the feces were determined. The test results of TC are as follows. Figure 1 As shown, the test results of TG are as follows Figure 2 As shown, the test results of LDL-C are as follows Figure 3 As shown, the test results of HDL-C are as follows Figure 4 As shown in Figure 2, the test results of intestinal flora species in feces are as follows Figure 5 As shown, the liver HE staining photos are as follows Figure 6 As shown, Figure 6 From left to right in the figure are the control group, model group, simvastatin group, and RS4 group.

[0071] from Figure 1-Figure 4It can be seen that the TC, TG, and LDL-C contents of the model group rats were significantly higher than those of the control group (p<0.01). Compared with the model group, the RS4 group can significantly reduce the content of TC, TG, and LDL-C (p<0.01) in serum, and the HDL-C (p<0.05) of the RS4 group is higher than that of the model group. The above results show that after treatment with the aerospace purple corn citrate starch of Example 1 of the present invention, the blood lipid indexes of the rats have improved to varying degrees, indicating that the aerospace purple corn citrate starch of the present invention can improve the content of TC, TG, LDL-C, and HDL-C in serum, and has a good improvement effect on blood lipid indexes.

[0072] from Figure 5 It can be seen that compared with the control group, the abundance of Bacteroidetes in the model group was significantly reduced, and the abundance of Firmicutes was significantly increased (P<0.01). Compared with the model group, after the treatment of aerospace purple corn citrate starch, the abundance of Bacteroidetes in the intestinal flora of the RS4 group increased, the abundance of Firmicutes decreased, and the ratio of Firmicutes / Bacteroidetes decreased, indicating that the aerospace purple corn citrate starch of the present invention helps to increase the abundance of Bacteroidetes and reduce the abundance of Firmicutes. It exerts the comprehensive regulatory effects of the liver-gut axis, immune-gut axis, and heart-gut axis, enhances immunity, improves the formation and accumulation of vascular fat, and reduces the incidence of cardiovascular and cerebrovascular diseases.

[0073] from Figure 6 It can be seen that no morphological changes were observed in the liver of the rats in the control group. In contrast, a large number of morphological changes occurred around the liver tissue of the rats in the model group, manifested as diffuse vesicular fatty degeneration, disordered cell arrangement, and enlarged adipocytes, indicating that a large number of fat droplets accumulated in the liver. There were no obvious changes in the liver of the rats in the RS4 group, indicating that after intervention with aerospace purple corn citrate starch, fatty lesions in the liver of hyperlipidemic rats can be significantly improved, and liver cells can be rearranged regularly, indicating that the aerospace purple corn citrate starch of the present invention can significantly improve liver damage and fat accumulation in mice in the model group.

[0074] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing aerospace purple corn citrate esterified starch, characterized in that: The preparation method comprises the following steps: Step 1, subjecting the aerospace purple corn starch to wet heat treatment, then adding it to the citric acid solution, stirring evenly, adding alkali solution to adjust the pH, and standing; Step 2, drying after standing, heating after grinding to react, washing the reaction product, and finally drying, grinding and sieving to obtain aerospace purple corn citrate esterified starch.

2. The preparation method according to claim 1, characterized in that: In step 1, The wet heat treatment comprises: drying the aerospace purple corn starch, adjusting the moisture content of the aerospace purple corn starch to 10-40%, storing it at 20-30° C. for 10-15 hours, then heating it at 80-110° C. for 8-16 hours, cooling it and drying it to obtain the aerospace purple corn starch after wet heat treatment; The aerospace purple corn starch treated with wet heat is added into a citric acid solution with a mass fraction of 40 to 70%, and the added amount of the citric acid is 10 to 60% of the added mass of the aerospace purple corn starch.

3. The preparation method according to claim 1, characterized in that: In step 1, NaOH solution was added to adjust the pH of the suspension to 1-3, and then the suspension was allowed to stand at 20-30°C to react for 15-20 hours.

4. The preparation method according to claim 1, characterized in that: In step 2, after the reaction is allowed to stand, the mixture is dried at 60-110° C. to a moisture content of 5%-10%.

5. The preparation method according to claim 1, characterized in that: In step 2, after grinding, the temperature is raised to 80-150° C. and reacted for 3-16 hours.

6. The preparation method according to claim 1, characterized in that: In step 2, Water is added to the reaction product for washing, and the washed reaction product is dried at 60-110° C., then ground and passed through an 80-mesh sieve.

7. A spaceflight purple corn citric acid esterified starch prepared according to the preparation method according to any one of claims 1 to 6.

8. An application of the aerospace purple corn citrate esterified starch as claimed in claim 7 in the fields of intestinal flora regulation, cardiovascular and cerebrovascular diseases, improving immunity, liver damage and fat accumulation.

Images