A method for delaying starch retrogradation

Abstract

The present invention relates to a method for effectively delaying starch retrogradation, and belongs to the technical field of agricultural product processing. The present invention uses starch as a substrate, uses an enzyme with transglycosidation ability to pretreat starch, changes the chain length distribution of amylopectin, increases the proportion of short amylopectin branches, and effectively delays the long-term retrogradation of starch. Enzyme-modified starch is complexed with lipids to form a starch-lipid inclusion complex, which hinders the entanglement and accumulation of the amylose double helix during the retrogradation process, and effectively delays the short-term retrogradation of starch.

Description

Technical Field

[0001] The invention relates to a method for effectively delaying starch retrogradation, and belongs to the technical field of agricultural product processing. Background Art

[0002] Natural starch is a polymer macromolecule with a semi-crystalline structure, mainly composed of two D-glucan polymers, amylose and highly branched amylopectin. During the gelatinization process of starch, the structure of starch granules is destroyed, amylose escapes, and starch granules change from an ordered crystalline state to a disordered state. During the cooling process, the destroyed amylose and amylopectin chains are rearranged and gradually combined into different crystal structures, which is called starch retrogradation. As an important raw material in the food industry, starch retrogradation can lead to adverse consequences such as hardening of starchy foods, roughening of tissue, and deterioration of flavor, thereby affecting the shelf life of the product and causing economic losses. Therefore, taking effective technical means to delay starch retrogradation is of great significance to prolonging the shelf life of starchy foods and reducing economic losses.

[0003] Starch retrogradation can be divided into two stages. Short-term retrogradation is the process in which amylose forms a double helix structure through hydrogen bonds and orderly stacks to form crystals. Long-term retrogradation is the process in which the external short chains of amylopectin are orderly rearranged by relying on the crystal nucleus to form a stable crystal structure, using the crystals formed by short-term retrogradation as crystal nuclei. Therefore, the changes in the proportion of side branches of amylose and amylopectin are closely related to starch retrogradation. Related studies have shown that starch-lipid inclusion complexes can inhibit the formation of amylose double helix structure, reduce the number of crystal nuclei, and delay the short-term retrogradation of starch. Enzymes with transglycosidic ability can effectively change the proportion of side branches of amylopectin, increase the proportion of short branches, hinder amylopectin from forming crystals by relying on crystal nuclei, and effectively inhibit the long-term retrogradation of starch. However, it is difficult to effectively inhibit the short-term and long-term retrogradation of starch by simply adding lipids or using biological enzyme treatment. Summary of the invention

[0004] In view of the problem that it is difficult to effectively inhibit the short-term and long-term retrogradation of starch by simply adding lipids or using biological enzyme treatment, the present invention utilizes the transglycosidic effect of enzymes to change the chain length distribution of amylopectin combined with the starch-lipid inclusion complex formed between enzyme-modified starch and lipids to effectively regulate the short-term and long-term retrogradation of starch.

[0005] The technical solution of this application is as follows:

[0006] A method for delaying starch retrogradation comprises first enzymolyzing starch with an enzyme capable of transglycosidation, and then constructing a starch-lipid inclusion complex to obtain anti-retrogradation starch.

[0007] Preferably, the method specifically comprises the following steps:

[0008] (1) Enzyme pretreatment of starch: Add starch to a buffer solution to prepare a starch milk with a mass concentration of 5-10%, gelatinize and cool, add an enzyme with transglycosidation ability to perform enzymatic hydrolysis, and inactivate the enzyme after the reaction to obtain a starch hydrolyzate;

[0009] (2) Heating method to construct starch-lipid inclusion complex: add lipid to the starch hydrolysate obtained in step (1), and cool to room temperature after the reaction is completed;

[0010] (3) Alcohol washing and centrifugation: centrifuging the solution obtained in step (2), washing, centrifuging, and removing the supernatant to remove unreacted lipids in the system;

[0011] (4) Freeze-drying, grinding and sieving: The precipitate obtained by centrifugation in step (3) is freeze-dried, ground and sieved to obtain the resistant starch.

[0012] Preferably, the starch in step (1) is one of corn starch, wheat starch, tapioca starch, potato starch and pea starch.

[0013] Preferably, the enzyme with transglycosidic ability described in step (1) is one of maltogenic amylase, glucan branching enzyme and transglucosidase; when the added enzyme is maltogenic amylase, the buffer refers to sodium acetate buffer with a pH of 6.8-7.0; when the added enzyme is glucan branching enzyme, the buffer refers to sodium acetate buffer with a pH of 6.0-6.5; when the added enzyme is transglucosidase, the buffer refers to sodium acetate buffer with a pH of 5.0-5.2.

[0014] Preferably, the lipid described in step (2) is one of octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid and octadecanoic acid; and the amount of lipid added is 2-10% of the dry weight of corn starch.

[0015] Preferably, the lipid described in step (2) needs to be dissolved in anhydrous ethanol before being added.

[0016] Preferably, the washing in step (3) refers to washing with ethanol.

[0017] Preferably, the freeze-drying condition in step (4) is vacuum freeze-drying.

[0018] Another object of the present invention is to protect the resistant retrogradation starch prepared by the above method.

[0019] Beneficial effects of the present invention

[0020] (1) The present invention uses starch as a substrate and uses an enzyme with transglycosidation ability to pretreat the starch, thereby changing the chain length distribution of amylopectin, increasing the proportion of short amylopectin branches, and effectively delaying the long-term retrogradation of starch.

[0021] (2) The present invention uses enzyme-modified starch to complex with lipids to form starch-lipid inclusion complexes, which hinder the entanglement and stacking of the amylose double helix during the retrogradation process and effectively delay the short-term retrogradation of starch.

[0022] (3) The present invention utilizes enzyme modification and starch-lipid inclusion complex construction to coordinately regulate the starch retrogradation process, improve the starch's anti-retrogradation ability, and extend the shelf life of starch foods. DETAILED DESCRIPTION

[0023] For a better understanding of the present invention, the embodiments of the present invention are further described below, but the embodiments of the present invention are not limited thereto.

[0024] Example 1

[0025] A method for effectively delaying starch retrogradation comprises the following steps:

[0026] (1) Treatment of corn starch with maltogenic amylase: corn starch was added to sodium acetate buffer at pH = 6.8-7.0 to prepare starch milk with a mass concentration of 5%; the starch milk was gelatinized at 90°C for 30 min, cooled to 50°C, 8 U / g of maltogenic amylase was added, and after enzymatic hydrolysis for 60 min, the starch milk was heated in a boiling water bath for 10 min to inactivate the enzyme;

[0027] (2) Construction of enzymatic corn starch-dodecanoic acid inclusion complex by heating method: dissolve 2% dodecanoic acid, which accounts for 2% of the dry weight of corn starch, in anhydrous ethanol and add it to the enzymatic hydrolyzate obtained in step (2), and heat it at 90°C for 60 minutes. After the reaction, cool the mixture to room temperature;

[0028] (3) Alcohol washing and centrifugation: Centrifuge the mixture obtained in step (2) at 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge. Repeat the operation twice.

[0029] (4) Freeze drying and grinding and sieving: The precipitate obtained in step (3) is subjected to vacuum freeze drying for 36 hours, and then ground and passed through an 80-mesh sieve to obtain an enzymatically hydrolyzed corn starch-dodecanoic acid inclusion complex.

[0030] Example 2

[0031] A method for effectively delaying starch retrogradation comprises the following steps:

[0032] (1) Treatment of corn starch with maltogenic amylase: corn starch was added to sodium acetate buffer at pH = 6.8-7.0 to prepare starch milk with a mass concentration of 5%; the starch milk was gelatinized at 90°C for 30 min, cooled to 50°C, 8 U / g of maltogenic amylase was added, and after enzymatic hydrolysis for 60 min, the starch milk was heated in a boiling water bath for 10 min to inactivate the enzyme;

[0033] (2) Construction of enzymatic corn starch-octadecanoic acid inclusion complex by heating method: 2% octadecanoic acid by dry weight of corn starch was dissolved in anhydrous ethanol and then added to the enzymatic hydrolyzate obtained in step (1), and heated at 90°C for 60 min. After the reaction, the mixture was cooled to room temperature;

[0034] (3) Alcohol washing and centrifugation: Centrifuge the mixture obtained in step (2) at 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge. Repeat the operation twice.

[0035] (4) Freeze drying and grinding and sieving: The precipitate obtained in step (3) is subjected to vacuum freeze drying for 36 hours, and then ground and passed through an 80-mesh sieve to obtain an enzymatically hydrolyzed corn starch-octadecanoic acid inclusion complex.

[0036] Example 3

[0037] A method for effectively delaying starch retrogradation comprises the following steps:

[0038] (1) Treatment of corn starch with maltogenic amylase: corn starch was added to sodium acetate buffer at pH = 6.0-6.5 to prepare starch milk with a mass concentration of 10%; the starch milk was gelatinized at 100°C for 60 min, cooled to 55°C, and 600 U / g of glucan branching enzyme was added. After enzymatic hydrolysis for 60 min, the starch milk was heated in a boiling water bath for 10 min to inactivate the enzyme;

[0039] (2) Construction of enzymatic corn starch-octadecanoic acid inclusion complex by heating method: 2% octadecanoic acid by dry weight of corn starch was dissolved in anhydrous ethanol and then added to the enzymatic hydrolyzate obtained in step (1), and heated at 90°C for 60 min. After the reaction, the mixture was cooled to room temperature;

[0040] (3) Alcohol washing and centrifugation: Centrifuge the mixture obtained in step (2) at 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge. Repeat the operation twice.

[0041] (4) Freeze drying and grinding and sieving: The precipitate obtained in step (3) is subjected to vacuum freeze drying for 36 hours, and then ground and passed through an 80-mesh sieve to obtain an enzymatically hydrolyzed corn starch-octadecanoic acid inclusion complex.

[0042] Example 4

[0043] A method for effectively delaying starch retrogradation comprises the following steps:

[0044] (1) Treatment of corn starch with maltogenic amylase: corn starch was added to sodium acetate buffer at pH = 5.0-5.2 to prepare starch milk with a mass concentration of 8%; the starch milk was gelatinized at 90°C for 30 min, cooled to 52°C, and then 1500 U / g of transglucosidase was added. After enzymatic hydrolysis for 240 min, the starch milk was heated in a boiling water bath for 10 min to inactivate the enzyme;

[0045] (2) Construction of enzymatic corn starch-octadecanoic acid inclusion complex by heating method: 2% octadecanoic acid by dry weight of corn starch was dissolved in anhydrous ethanol and then added to the enzymatic hydrolyzate obtained in step (1), and heated at 90°C for 60 min. After the reaction, the mixture was cooled to room temperature;

[0046] (3) Alcohol washing and centrifugation: Centrifuge the mixture obtained in step (2) at 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge. Repeat the operation twice.

[0047] (4) Freeze drying and grinding and sieving: The precipitate obtained in step (3) is subjected to vacuum freeze drying for 36 hours, and then ground and passed through an 80-mesh sieve to obtain an enzymatically hydrolyzed corn starch-octadecanoic acid inclusion complex.

[0048] Example 5

[0049] A method for effectively delaying starch retrogradation comprises the following steps:

[0050] (1) Treatment of corn starch with maltogenic amylase: corn starch was added to sodium acetate buffer at pH = 5.0-5.2 to prepare starch milk with a mass concentration of 7%; the starch milk was gelatinized at 90°C for 30 min, cooled to 55°C, and then 3000 U / g of transglucosidase was added. After enzymatic hydrolysis for 60 min, the starch milk was heated in a boiling water bath for 10 min to inactivate the enzyme;

[0051] (2) Construction of enzymatic corn starch-octadecanoic acid inclusion complex by heating method: 2% octadecanoic acid by dry weight of corn starch was dissolved in anhydrous ethanol and then added to the enzymatic hydrolyzate obtained in step (1), and heated at 90°C for 60 min. After the reaction, the mixture was cooled to room temperature;

[0052] (3) Alcohol washing and centrifugation: Centrifuge the mixture obtained in step (2) at 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge. Repeat the operation twice.

[0053] (4) Freeze drying and grinding and sieving: The precipitate obtained in step (3) is subjected to vacuum freeze drying for 36 hours, and then ground and passed through an 80-mesh sieve to obtain an enzymatically hydrolyzed corn starch-octadecanoic acid inclusion complex.

[0054] Comparative Example 1

[0055] (1) Treatment of corn starch with maltogenic amylase: corn starch was added to sodium acetate buffer at pH = 6.8 to prepare a starch milk with a mass concentration of 5%. The starch milk was gelatinized at 90 °C for 30 min, cooled to 50 °C, and then 8 U / g maltogenic amylase was added. After enzymatic hydrolysis for 60 min, the starch milk was heated in a boiling water bath for 10 min to inactivate the enzyme, and then cooled to room temperature.

[0056] (2) Alcohol washing and centrifugation: centrifuge the mixture obtained in step (1) at 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge, repeating the operation twice;

[0057] (3) Freeze drying and grinding and sieving: The precipitate obtained in step (2) is subjected to vacuum freeze drying for 36 hours, and then ground and passed through an 80-mesh sieve to obtain enzymatically hydrolyzed corn starch.

[0058] Compared with Example 1, except that dodecanoic acid was not added to form the starch-lipid inclusion complex, the remaining operation steps were the same as those of Example 1.

[0059] Comparative Example 2

[0060] (1) Corn starch gelatinization: corn starch was added to sodium acetate buffer at pH = 6.8 to prepare a starch milk with a mass concentration of 5%; the starch milk was gelatinized at 90°C for 30 min;

[0061] (2) Construction of corn starch-dodecanoic acid inclusion complex by heating method: dissolve 2% dodecanoic acid in anhydrous ethanol and add it to the mixture obtained in step (1), and heat it at 90°C for 60 minutes. After the reaction, cool the mixture to room temperature;

[0062] (3) Alcohol washing and centrifugation: centrifuge the mixture obtained in step (2) at a speed of 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge, repeating the operation twice;

[0063] (4) Freeze drying and grinding and sieving: The precipitate obtained in step (3) is freeze-dried in vacuum for 36 hours, ground, and passed through an 80-mesh sieve to obtain a corn starch-dodecanoic acid inclusion complex.

[0064] Compared with Example 1, except that the starch is not pretreated with maltogenic amylase, the remaining operation steps are the same as those of Example 1.

[0065] Comparative Example 3

[0066] (1) Corn starch gelatinization: corn starch was added to sodium acetate buffer at pH = 6.8 to prepare a starch milk with a mass concentration of 5%; the starch milk was gelatinized at 90°C for 30 min;

[0067] (2) Corn starch-octadecanoic acid inclusion complex gelatinization method: 2% of the dry weight of corn starch is dissolved in anhydrous ethanol and then added to the mixture obtained in step (1), and heated at 90°C for 60 minutes. After the reaction, the mixture is cooled to room temperature;

[0068] (3) Alcohol washing and centrifugation: centrifuge the mixture obtained in step (2) at a speed of 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge, repeating the operation twice;

[0069] (4) Freeze drying and grinding and sieving: The precipitate obtained in step (3) is subjected to vacuum freeze drying for 36 hours, and then ground and passed through an 80-mesh sieve to obtain a corn starch-octadecanoic acid inclusion complex.

[0070] Compared with Example 2, except that the corn starch is not pretreated with maltogenic amylase, the remaining steps are the same as those in Example 2.

[0071] Comparative Example 4

[0072] (1) Corn starch gelatinization: corn starch was added to sodium acetate buffer at pH = 6.8 to prepare a starch milk with a mass concentration of 5%; the starch milk was gelatinized at 90 °C for 30 min and cooled to room temperature;

[0073] (2) Alcohol washing and centrifugation: centrifuge the starch paste obtained in step (1) at a speed of 5000 rpm for 10 min, discard the supernatant, wash the precipitate with ethanol, and centrifuge, repeating the operation twice;

[0074] (3) Freeze drying and grinding and sieving: The precipitate obtained in step (2) is vacuum freeze-dried for 36 hours, ground, and passed through an 80-mesh sieve to obtain a corn starch sample.

[0075] Compared with Example 1, except that maltogenic amylase pretreatment was not performed and dodecanoic acid was not added to form corn starch-lipid inclusion complex, the remaining operation steps were the same as those in Example 1.

[0076] The starch samples obtained in Examples 1-2 and Comparative Examples 1-4 were subjected to retrogradation property determination:

[0077] Determination method of retrogradation properties:

[0078] The retrogradation properties of starch are characterized by the retrogradation enthalpy of starch. The retrogradation enthalpy of the retrogradation sample is determined by differential scanning calorimetry (DSC) under the purge and protection of high-purity nitrogen. The determination method is as follows: the freeze-dried starch powder prepared in Examples 1-2 and Comparative Examples 1-4 is mixed with water to prepare a starch milk with a mass percentage of 10%, gelatinized at 95°C for 30 minutes, cooled to room temperature, and then placed in a 4°C refrigerator for sealed storage for 13 days to allow it to retrograde. The retrogradation sample is vacuum freeze-dried for 48 hours, ground and sieved through an 80-mesh sieve. 2 mg of the retrogradation sample powder is mixed with 6 μL of deionized water in an aluminum crucible, sealed, and equilibrated at room temperature for 12 hours. After equilibration, the crucible is scanned from 20°C to 120°C at a heating rate of 10°C / min, and an empty crucible is used for comparison. The enthalpy value is calculated from the DSC curve using Netzsch analysis software. (The larger the retrogradation enthalpy value, the higher the degree of retrogradation of the sample and the weaker the anti-retrogradation ability).

[0079] Table 1 Regeneration enthalpy of samples prepared in Examples 1-2 and Comparative Examples 1-4

[0080]

[0081] As can be seen from Table 1, the enzymatic corn starch-dodecanoic acid / octadecanoic acid inclusion complex prepared by chelating corn starch treated with maltogenic amylase with lipids in the present invention has a retrogradation enthalpy of only 0.29 J / g (Example 1) and 0.32 J / g (Example 2), which is significantly lower than that of Comparative Examples 1-4, indicating that the samples prepared by this method have good anti-retrogradation ability. When dodecanoic acid is not added to form the inclusion complex, the retrogradation enthalpy of the sample increases compared with Example 1 (Comparative Example 1), indicating that the formation of the starch-lipid inclusion complex can inhibit starch retrogradation to a certain extent. When corn starch is not pretreated with maltogenic amylase, the retrogradation enthalpy of the sample increases significantly compared with Examples 1 and 2 (Comparative Examples 2 and 3), indicating that the increase in the proportion of short branches of amylopectin can effectively delay starch retrogradation. When corn starch is not pretreated with maltogenic amylase and dodecanoic acid is not added, the retrogradation enthalpy value of the sample is the largest (Comparative Example 4), which indicates that the synergistic treatment of enzyme modification and starch-lipid inclusion complex construction can effectively regulate the starch retrogradation process. The modified starch prepared by this method has good anti-retrogradation ability.

Claims

1. A method for delaying starch retrogradation, characterized in that: Firstly, the starch is enzymatically hydrolyzed with an enzyme capable of transglycosidation, and then a starch-lipid inclusion complex is constructed to obtain the anti-retrogradation starch; specific The following steps are involved: (1) Enzyme pretreatment of starch: starch is added to sodium acetate buffer to prepare starch milk with a mass concentration of 5%-10%, gelatinized at 90°C for 30 minutes, cooled to 50°C, and then an enzyme with transglycosidation ability is added for enzymatic hydrolysis. After the reaction is completed, the starch is heated in a boiling water bath for 10 minutes to inactivate the enzyme, thereby obtaining a starch hydrolysate; the enzyme with transglycosidation ability is one of glucan branching enzyme and transglucosidase; when the added enzyme is glucan branching enzyme, the buffer refers to sodium acetate buffer with a pH of 6.0-6.5; when the added enzyme is transglucosidase, the buffer refers to sodium acetate buffer with a pH of 5.0-5.2; (2) Heating method to construct starch-lipid inclusion complex: dissolve lipid in anhydrous ethanol and add it to the starch hydrolysate obtained in step (1), heat at 90°C for 60 min, and cool to room temperature after the reaction is completed; (3) Alcohol washing and centrifugation: The solution obtained in step (2) is centrifuged, the precipitate is washed with ethanol, centrifuged, and the supernatant is removed to remove unreacted lipids in the system; (4) Freeze-drying, grinding and sieving: The precipitate obtained by centrifugation in step (3) is vacuum freeze-dried, ground and sieved to obtain the resistant starch.

2. The method for delaying starch retrogradation according to claim 1, characterized in that: The starch in step (1) is one of corn starch, wheat starch, tapioca starch, potato starch and pea starch.

3. The method for delaying starch retrogradation according to claim 1, characterized in that: The lipid described in step (2) is one of octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid and octadecanoic acid; the amount of lipid added is 2%-10% of the dry weight of corn starch.

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