High-resistance corn starch and preparation method thereof
By combining citric acid esterification and plasma-activated water with high-pressure steam treatment, the problem of low efficiency in traditional corn starch modification was solved, significantly increasing the content of resistant starch and improving the gelatinization properties of starch, thus expanding its application in food.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENYANG AGRI UNIV
- Filing Date
- 2025-12-26
- Publication Date
- 2026-04-21
AI Technical Summary
Traditional corn starch modification processes are inefficient, have limited ability to increase resistant starch content, and the modified starch is hard and prone to retrogradation after gelatinization, which limits its application in food.
A dual physical modification method combining chemical modification was employed, using citric acid esterification combined with low-pH plasma activation of water and high-pressure steam treatment of corn starch to shorten the modification time, increase the resistant starch content, and remove excess citric acid by washing to form stable resistant starch.
It significantly increased the resistant starch content of corn starch, improved the gelatinization characteristics of starch, reduced the retrogradation value and gelatinization temperature, and broadened its application range in food processing.
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Abstract
Description
Technical Field
[0001] This invention relates to a highly resistant corn starch and its preparation method, belonging to the field of food processing technology. Background Technology
[0002] Resistant starch is a type of starch that cannot be digested and absorbed by the human small intestine. Instead, it enters the large intestine and is fermented and utilized by intestinal flora, with physiological functions similar to dietary fiber. However, natural starch has a low resistant starch content, making it difficult to exert its intended nutritional and health benefits in specific populations. Corn, as the main raw material for starch production, ranks first in total grain production in China. However, the inherent characteristics of corn starch severely limit its application. Unmodified natural corn starch has a low resistant starch content and a hard texture, and it is prone to retrogradation after gelatinization, resulting in a rough texture in food products. Therefore, modifying corn starch to improve its functional properties (especially resistant starch content) has become an important way to promote the development of the corn starch industry towards higher value. Currently, starch is modified through physical, chemical, or biological methods. Traditional wet processing for citrate starch has the problem of excessively long processing times; for example, hot wet processing of corn starch requires 12 hours of heat treatment, while dry processing suffers from insufficient material mixing. Furthermore, in traditional processes, the dense crystalline regions of starch make it difficult for citric acid to penetrate, resulting in only a small amount of esterification occurring in the amorphous regions. This fails to form stable steric hindrance against digestion, leading to limited improvement in resistant starch content. Therefore, there is an urgent need to develop a highly efficient, green, and significantly improved corn starch modification technology to further broaden the application range of corn starch. Summary of the Invention
[0003] To address the technical problems of low efficiency and limited improvement in resistant starch content in existing modification processes, this invention provides a high-resistant corn starch and its preparation method. This invention achieves high-resistant corn starch through a combination of physical and chemical modification. Specifically, it employs citric acid esterification, combined with plasma-activated water rich in low pH and active substances instead of distilled water and high-pressure steam treatment, effectively shortening the corn starch modification time, inhibiting starch retrogradation, and increasing the resistant starch content.
[0004] Citric acid readily undergoes esterification under high temperature and suitable moisture conditions, dehydrating to form citric anhydride. During heating, citric anhydride adheres to starch to form starch-citric acid ester derivatives, increasing the content of resistant starch. By combining high-pressure steam and plasma-activated water treatment, the degree of citric acid esterification can be significantly improved, and excess citric acid can be washed away after modification, thereby achieving multiple goals such as cleaner labels, improved properties, and expanded applications.
[0005] A method for preparing high-resistant corn starch involves dissolving citric acid in water using plasma-activated methods to obtain a citric acid solution; then adding corn starch to the citric acid solution, subjecting it to high-pressure steam treatment, drying it, and when the moisture content reaches 10%, removing it, grinding it, washing it, drying it again, grinding it, and sieving it to obtain high-resistant corn starch.
[0006] In the above technical solution, the mass-to-volume ratio of citric acid to plasma-activated water in the citric acid solution is 1g : 25~28mL.
[0007] In the above technical solution, the mass-to-volume ratio of corn starch to citric acid solution is 5 g : 40~45 mL.
[0008] In the above technical solution, the plasma-activated water is prepared by the following method: distilled water is treated with a low-temperature plasma-activated water generator for 14-16 minutes.
[0009] In the above technical solution, the high-pressure steam treatment conditions are treatment at 121°C for 19-21 min in a high-pressure steam sterilizer.
[0010] In the above technical solution, the first drying condition is drying at 55℃ for 12~24 h.
[0011] In the above technical solution, the second drying condition is drying at 55℃ for 12~15 h.
[0012] In the above technical solution, the product is first washed three times with distilled water, and then washed once with ethanol to remove excess citric acid.
[0013] Another object of the present invention is to provide a highly resistant corn starch obtained by the above method.
[0014] Furthermore, the high-resistant corn starch contains 75% to 80% resistant starch.
[0015] The beneficial effects of this invention are: 1. Improved viscosity and gelatinization temperature: The high-resistant corn starch obtained by this invention exhibits a significant decrease in peak viscosity, a reduction in retrogradation value, and an increase in gelatinization temperature. This is attributed to the synergistic effect of active substances and acidic components in plasma-activated water with citric acid. This invention effectively optimizes the gelatinization behavior of starch; the improved starch is less prone to retrogradation and better meets the precise requirements of gelatinization processes in modern food processing.
[0016] 2. Increased resistant starch content: The high resistant corn starch obtained by this invention has a significantly increased resistant starch content, which is mainly due to the fact that citric acid esterification and plasma-activated water destroy the stable structure of slow-digesting starch, promoting its conversion into resistant starch. Attached Figure Description
[0017] Figure 1 The figure shows the effect of different modification methods on the gelatinization properties of corn starch. In the figure, NCS is native corn starch, HPS-DW-CCS is the corn starch obtained in Comparative Example 1, and HPS-PAW-CCS is the high-resistance corn starch obtained in Example 1.
[0018] Figure 2 The figure shows the effect of different modification methods on the digestibility of corn starch. NCS is native corn starch, HPS-DW-CCS is corn starch obtained in Comparative Example 1, and HPS-PAW-CCS is high-resistant corn starch obtained in Example 1. Detailed Implementation
[0019] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.
[0020] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.
[0021] Example 1 A method for preparing highly resistant corn starch includes the following steps: Distilled water was treated with a low-temperature plasma-activated water generator for 15 min to obtain plasma-activated water. 1.66 g of citric acid was dissolved in 45 mL of the plasma-activated water to obtain a citric acid solution. 5 g of corn starch was added to the citric acid solution and placed in an autoclave at 121°C for 20 min. After the reaction was complete, the mixture was removed, poured into a glass petri dish, and dried in a 55°C oven. When the moisture content of the sample reached 10%, it was removed, ground, washed three times with distilled water, and once with ethanol to remove excess citric acid. The mixture was then placed in an oven until completely dry, ground again, and passed through a 100-mesh sieve to obtain the final product.
[0022] Comparative Example 1 A method for preparing corn citrate starch by high-pressure steam distillation includes the following steps: Dissolve 1.66 g of citric acid in 45 mL of distilled water to obtain a citric acid solution. Add 5 g of corn starch to the citric acid solution prepared above, and place it in an autoclave at 121℃ for 20 min. After the reaction is complete, remove it and pour it into a glass petri dish, then place it in a 55℃ oven to dry. When the moisture content of the sample is 10%, remove it, grind it, wash it three times with distilled water and once with ethanol to remove excess citric acid, then place it in an oven to dry completely, grind it, and pass it through a 100-mesh sieve to obtain the final product.
[0023] Effects of different modification methods on the gelatinization properties of corn starch The corn starch obtained in Example 1 and Comparative Example 1 was subjected to gelatinization characteristics testing according to standard NY / T 3868-2021: 3 g of the sample was added to a test cylinder containing 25 g of distilled water. A stirrer was placed in the cylinder and the mixture was rapidly stirred up and down until the sample was completely dispersed and uniform. The sample was then placed in a rapid viscosity analyzer for measurement. The results are shown in Table 1 and... Figure 1 Gelatinization properties affect the cooking and eating quality of starchy foods. Figure 1 As shown in Table 1, the peak viscosity, minimum viscosity, decay value, final viscosity, and retrogradation value of modified corn starch were significantly reduced. The decrease in peak viscosity of HPS-DW-CCS and HPS-PAW-CCS may be due to the high temperature and pressure of the high-pressure steam destroying the crystalline and amorphous structures of the starch granules, causing partial degradation of the starch molecular chains and reducing the water absorption and swelling capacity of the granules. Comparing HPS-DW-CCS and HPS-PAW-CCS, the peak viscosity of HPS-PAW-CCS is higher than that of HPS-DW-CCS, which is speculated to be due to the cross-linking of starch molecules induced by plasma oxidation, which may have resulted in a higher peak viscosity.
[0024] Compared to NCS (untreated corn starch), the two modified starches showed significantly lower retrogradation values: HPS-DW-CCS had a retrogradation value of 323, and HPS-PAW-CCS had a value of 371. This is because the ester groups introduced into the starch molecular chains by the citric acid esterification reaction disrupt the hydrogen bond sites between molecular chains, hindering the rearrangement and crystallization of starch molecules, thus effectively inhibiting starch retrogradation. The retrogradation value of HPS-PAW-CCS was slightly higher than that of HPS-DW-CCS. This is because the acidic components in the plasma-activated water can produce low-molecular-weight hydrolysis products, and the esterification reaction introduces steric hindrance into the starch molecules, thus hindering the orderly arrangement of starch molecules.
[0025] The gelatinization temperature of NCS was 75.85℃, and the peak viscosity time was 5.134 min, indicating that the crystalline structure of native starch granules is relatively weak, allowing them to begin gelatinization at a lower temperature and quickly reach peak viscosity. The gelatinization temperature of modified starch was significantly higher because high-pressure steam treatment rearranged the crystalline structure of the starch granules, forming a more stable crystal structure. Simultaneously, esterification modification enhanced intermolecular forces, requiring even higher temperatures to disrupt the crystal structure and gelatinize the starch granules.
[0026] The gelatinization temperature and peak time of HPS-PAW-CCS are lower than those of HPS-DW-CCS. This is because the active components of plasma-activated water can destroy part of the crystalline structure of starch granules, reduce the stability of the crystal structure, and enhance the expansion and breakage of starch granules in the aqueous medium. As a result, the gelatinization temperature is lowered and the peak time is shortened, which is more conducive to the gelatinization application of starch in food processing.
[0027] Table 1. Effects of different modification methods on the gelatinization properties of corn starch.
[0028] Effects of different modification methods on the digestibility of corn starch The digestibility of the modified corn starch obtained in Example 1 and Comparative Example 1 was determined: 200 mg of the sample (dry basis) was accurately weighed into a 50 mL centrifuge tube with a screw cap, and 15 mL of 0.2 mol / L acetate-sodium acetate buffer solution with pH 5.2 was added. After mixing, the mixture was placed in a boiling water bath for 30 min until complete gelatinization. After cooling to room temperature, 6 glass beads were added, and the mixture was placed in a 37°C constant temperature shaking water bath. Adipoglucosidase (30 U) and porcine pancreatic α-amylase (3 x 10⁻⁶ U) were added. 3 10 mL of the mixed enzyme (U) was placed in a 37℃ constant temperature water bath shaker and the time was accurately recorded. After hydrolysis for 20 min and 120 min respectively, 0.5 mL of the hydrolysate was taken out and placed in 4 mL of ethanol solution to inactivate the enzyme. The glucose content was determined by the DNS method, and RDS, SDS and RS were calculated according to the following formulas. The results are shown in Table 1 and 2. Figure 2 .
[0029]
[0030] Wherein, G0 represents the glucose content (mg) produced after 0 min of enzyme hydrolysis of the sample; G 20 The glucose content (mg) produced after 20 min of enzymatic hydrolysis of the sample to be tested; G 120 The glucose content (mg) produced after 120 min of enzymatic hydrolysis of the sample to be tested; TS is the total starch dry weight (mg).
[0031] Depend on Figure 2As shown in Table 2, the content of rapidly digestible starch in the modified corn starch decreased compared to the original corn starch. This is because the high temperature and pressure of the high-pressure steam destroyed the crystalline regions of the starch granules, causing some crystalline starch to transform into an amorphous form. However, the subsequent citric acid esterification reaction prevented the expansion and gelatinization of the corn starch granules during heating, thus limiting the binding ability of digestive enzymes to the starch granules. In contrast, HPS-PAW-CCS had a higher content of rapidly digestible starch than HPS-DW-CCS. This is because plasma-activated water-active substances (hydrogen peroxide, ozone) promote pits, cracks, and surface roughness, making it easier for amylase to enter the granules and contact starch molecules, thereby improving enzymatic hydrolysis efficiency to some extent.
[0032] Compared to native corn starch, HPS-DW-CCS has a higher content of slowly digestible starch. This is likely because the high-pressure steam treatment partially rearranges the crystalline structure of the starch granules, resulting in a more compact arrangement of starch molecular chains. The mild effect of citric acid esterification modification does not destroy this crystalline structure, only introducing ester groups on the surface of the molecular chains. Amylases have difficulty penetrating it quickly and can only hydrolyze it slowly, thus significantly increasing the content of slowly digestible starch. In contrast, HPS-PAW-CCS has a low content of slowly digestible starch, possibly due to the abundant H+ in PAW. + Due to the tight arrangement of the chains, the ions induce the formation of additional hydrogen bonds between the double helixes and enhance the crystal structure. At the same time, the plasma-activated active substances in the water promote the diffusion and penetration of citric acid into the starch molecules and accelerate the esterification reaction with starch. This makes the ester groups on the starch molecular chains more densely distributed and the degree of cross-linking higher, forming a dense network structure that is difficult for amylase to hydrolyze. The SDS component, which could originally be slowly hydrolyzed, is further converted into resistant starch.
[0033] Compared to the other two corn starches, HPS-PAW-CCS has a higher resistant starch content. The moisture content, temperature, and acidity of the plasma-activated water treatment affect the amorphous regions of the starch, resulting in shorter chains with higher fluidity. Therefore, there is a higher rearrangement as a new double helix structure. The plasma-activated water disrupts the stable structure of slowly digestible starch, promoting its conversion to resistant starch. HPS-DW-CCS has the lowest resistant starch content, only 59.24226%. This is because the core function of the high-pressure steam combined with distilled water citric acid esterification modification is to induce the starch to form a stable B-type crystalline structure, thereby increasing the content of slowly digestible starch, rather than resistant starch. Under this modification method, the degree of cross-linking of starch molecules is lower, and the retrogradation effect is weaker, therefore the RS content is lower than that of NCS and HPS-PAW-CCS.
[0034] Table 2. Results of the effects of different modification methods on the digestibility of corn starch.
Claims
1. A method for preparing highly resistant corn starch, characterized in that: Citric acid was dissolved in water using plasma activation to obtain a citric acid solution. Then, corn starch was added to the citric acid solution, treated with high-pressure steam, dried, and when the moisture content was 10%, it was taken out, ground, washed, dried again, ground, and sieved to obtain high-resistance corn starch.
2. The preparation method according to claim 1, characterized in that: The mass-to-volume ratio of citric acid to plasma-activated water in the citric acid solution is 1 g : 25~28 mL.
3. The preparation method according to claim 1, characterized in that: The mass-to-volume ratio of corn starch to citric acid solution is 5 g : 40~45 mL.
4. The preparation method according to claim 1, characterized in that: The plasma-activated water is prepared by treating distilled water with a low-temperature plasma-activated water generator for 14-16 minutes.
5. The preparation method according to claim 1, characterized in that: The high-pressure steam treatment conditions are: treatment at 121°C for 19-21 min in a high-pressure steam sterilizer.
6. The preparation method according to claim 1, characterized in that: The first drying conditions were 55 ℃ for 12-24 h; the second drying conditions were 55 ℃ for 12-15 h.
7. The preparation method according to claim 1, characterized in that: Wash three times with distilled water, then wash once with ethanol to remove excess citric acid.
8. The highly resistant corn starch prepared by the method according to any one of claims 1 to 7.
9. The high-resistance corn starch according to claim 8, characterized in that: The high-resistant corn starch contains 75% to 80% resistant starch.