Preparation method of resistant dextrin with different starch sources

Abstract

The invention relates to the field of food processing, in particular to a preparation method of resistant dextrin with different starch sources. According to the invention, corn starch, wheat starch, pea starch and cassava starch are used as raw materials, and the addition amounts of alpha-amylase, transglucosidase and branched glycosyltransferase are controlled to prepare the resistant dextrin with different starch sources. Compared with a traditional acid heating method, the method has the advantages that alpha-1, 4 glucosidic bonds can be effectively reduced, alpha-1, 6 glucosidic bonds and other non-starch glucosidic bonds can be increased, the branch structure of the resistant dextrin is increased, and the resistant components of the resistant dextrin are increased. Different starches are used for preparing the resistant dextrin, and a high-quality starch source for preparing the resistant dextrin can be found out.

Description

Technical Field

[0001] The invention relates to the field of food processing, and in particular to a method for preparing resistant dextrins from different starch sources. Background Art

[0002] As people's living standards improve, the demand for high-quality food continues to grow, and the consumption of high-calorie, high-fat and refined foods has increased significantly, which has led to a decrease in dietary fiber intake, followed by an increase in the prevalence of chronic diseases such as coronary heart disease and diabetes. Dietary fiber is the seventh essential nutrient for humans and is essential for improving human nutritional status and regulating body functions.

[0003] Resistant dextrin is a soluble dietary fiber prepared from starch. Resistant dextrin has special physiological functions, such as lowering blood sugar, enhancing satiety, regulating intestinal bacterial growth, and improving the clinical manifestations of polycystic ovary syndrome. The resistance of resistant dextrin lies in its internal branching structure, which prevents it from being hydrolyzed by digestive enzymes, thereby producing resistance to digestion. In addition to the α-1, 4 bonds and α-1, 6 bonds existing in starch itself, resistant dextrin also has many non-starch glycosidic bonds. The dense distribution area of ​​new glycosidic bonds and α-1, 6 bonds is the main reason for digestive enzyme resistance. Resistant dextrin has good processing performance, a slightly sweet taste, and is acid-resistant, pressure-resistant, heat-resistant, frost-resistant, browning-resistant and storage-resistant. Therefore, it is widely used in food and can be used as a raw material to make bread, biscuits and beverages. Different starch sources can be used to prepare resistant dextrin, but the most studied one is corn resistant dextrin, and there is little research on the preparation of resistant dextrin from other starch sources. The structural characteristics and physiological functions of resistant dextrin are related to the raw materials and their starch composition. Therefore, the selection of raw materials is crucial. In addition, transaminase and branching enzyme can promote the generation of branched structures in resistant dextrin and increase the resistance components of resistant dextrin. Adding new enzymes during the preparation process is of great help in producing high-quality resistant dextrin. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing resistant dextrins from different starch sources. The present invention utilizes the combined action of α-amylase, transglucosidase and branched glycosyltransferase to improve the branching structure of resistant dextrin, prepare resistant dextrins from different starch sources with high branching degree, and improve digestibility.

[0005] The present invention is achieved through the following technical solutions: A method for preparing resistant dextrins from different starch sources comprises the following steps: S1, after starch is dissolved in distilled water, hydrochloric acid is added to the starch solution for acidification and filtration, and then dried to obtain acidified starch; S2, placing the acidified starch at high temperature to react to obtain pyrodextrin; S3, dissolving the pyrodextrin in water, adding α-amylase to the pyrodextrin solution, heating it in a water bath, then adding transglucosidase and branched glycosyltransferase, and continuing the reaction to obtain an enzymolysis solution; S4. Add ethanol solution to the enzymatic hydrolyzate for alcohol precipitation to obtain resistant dextrin.

[0006] As a preferred embodiment, in step S1, the addition ratio of starch and distilled water is limited to 10g starch: 15mL distilled water; The concentration of the hydrochloric acid is 0.5 mol / L, and the ratio of the hydrochloric acid solution to distilled water is 1:15.

[0007] The drying temperature is 70° C., and the water activity of the acidified starch is less than 0.1. In a moisture environment with a water activity of less than 0.1, various microorganisms do not carry out life activities and will not cause reactions that affect food quality.

[0008] As a preferred solution, in step S2, the acidified starch is heated at 170° C. for 3.5 hours to obtain pyrodextrin. The high temperature of 170° C. can gelatinize the starch to a greater extent, while the degree of Maillard reaction and saccharification reaction is relatively small.

[0009] As a preferred embodiment, in step S2, the addition ratio of pyrodextrin and distilled water is limited to 5 g pyrodextrin: 10 mL distilled water; The addition amount of the α-amylase is 20-100 U / starch dry weight (g); The water bath heating condition was 70°C for 2 h; The amount of transglucosidase added is 50-200 U / starch dry weight (g), and the amount of branched glycosyltransferase added is 200 U / starch dry weight (g); The subsequent reaction temperature was 56°C for 16 h.

[0010] Among them, 70℃ is the optimum temperature for α-amylase, and 56℃ is the optimum temperature for transglucosidase. At this temperature, the enzyme activity is the highest and the enzymatic reaction can occur more fully.

[0011] As a preferred embodiment, in step S4, the ethanol solution is 95% ethanol, the volume ratio of the ethanol solution to the enzymatic hydrolysate is 1:1, and the resistant dextrin is obtained after 4 times of alcohol precipitation.

[0012] As a preferred embodiment, the starch is corn, wheat, pea and tapioca starch.

[0013] The beneficial effects of the present invention are: Compared with the traditional acid-heat method, the present invention adds transaminase during the preparation process, which can effectively reduce α-1,4 glycosidic bonds, increase α-1,6 glycosidic bonds and other non-starch glycosidic bonds, increase the branch structure of resistant dextrin, and improve the resistance component of resistant dextrin. Alpha-amylase, transglucosidase and branching glycosyltransferase cooperate with each other, and α-amylase provides conditions for transaminase and branching enzyme to prepare multiple branches. Alpha-amylase breaks the α-1,4 glycosidic bonds in the starch structure in advance, releasing small molecules, and transglucosidase and branching glycosyltransferase jointly aggregate free small molecule polymers onto glucan, while α-amylase does not prevent the occurrence of such reactions. Therefore, the three enzymes complement each other and work together to prepare highly branched resistant dextrin. In addition, the present invention uses different starches to prepare resistant dextrin, and can find out the high-quality starch source for preparing resistant dextrin. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the nuclear magnetic resonance spectrum of the resistant dextrin prepared in Example 5-8. DETAILED DESCRIPTION

[0015] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Example 1 Weigh 10g corn starch and dissolve it in 15mL water, then add 1mL of 0.5mol / L HCl solution to the starch suspension. Filter the acidified starch solution on filter paper for 8h, and dry the filtered acidified starch in a 70℃ oven until the water activity is less than 0.1. Then, keep the acidified starch at 170℃ for 3.5h to obtain pyrodextrin. Dissolve pyrodextrin in 2 times the volume of water based on dry weight, add 20U / starch dry weight (g) α-amylase to the pyrodextrin solution and react in a 70℃ water bath for 2h, then add 50U / starch dry weight (g) transglucosidase and 200U / starch dry weight (g) branched glycosyltransferase and react at 56℃ for 16h, and finally use 95% ethanol to precipitate four times to obtain the resistant dextrin product.

[0017] Example 2 Weigh 10g corn starch and dissolve it in 15mL water, then add 1mL of 0.5mol / L HCl solution to the starch suspension. Filter the acidified starch solution on filter paper for 8h, and dry the filtered acidified starch in a 70℃ oven until the water activity is less than 0.1. Then, keep the acidified starch at 170℃ for 3.5h to obtain pyrodextrin. Dissolve pyrodextrin in 2 times the volume of water based on dry weight, add 20U / starch dry weight (g) α-amylase to the pyrodextrin solution and react in a 70℃ water bath for 2h, then add 200U / starch dry weight (g) transglucosidase and 200U / starch dry weight (g) branched glycosyltransferase and react at 56℃ for 16h, and finally use 95% ethanol to precipitate four times to obtain the resistant dextrin product.

[0018] The difference between the preparation method of Example 2 and Example 1 is that the addition amount of α-amylase and transglucosidase is 20 U / starch dry weight (g) and 200 U / starch dry weight (g), respectively. The other conditions are all the same.

[0019] Example 3 The difference from the preparation method of Example 1 is that the addition amounts of α-amylase and transglucosidase are 20 U / starch dry weight (g) and 500 U / starch dry weight (g), respectively. The other conditions are all the same.

[0020] Comparative Example 1 The difference from the preparation method of Example 1 is that no transglucosidase is added, and the other conditions are all the same.

[0021] Examples 1-3 and Comparative Example 1 explored the effect of no added transglucosidase on the product of resistant dextrin. The results are shown in Table 1.

[0022] Table 1: The role of transglucosidase is to connect the small molecules broken from the α-1,4 glycosidic bond to the main chain in the form of a branched chain using the α-1,6 glycosidic bond. When the amount of transglucosidase added is 50U / starch dry weight (g), the α-1,4 glycosidic bond content is as high as 61.13%; when the amount of transglucosidase added is 200U / starch dry weight (g), the α-1,4 glycosidic bond accounts for 58.13%. When the amount of transglucosidase added is adjusted to 500U / starch dry weight (g), the α-1,6 glycosidic bond content only increases slightly, and the α-1,4 glycosidic bond does not decrease significantly, indicating that the amount of transglucosidase added is 200U / starch dry weight (g) to reach a certain saturation state, which can greatly improve the branching structure of resistant dextrin.

[0023] Example 4 The difference from the preparation method of Example 2 is that the addition amounts of α-amylase and transglucosidase are 40 U / starch dry weight (g) and 200 U / starch dry weight (g), respectively. The other conditions are all the same.

[0024] Example 5 The preparation method is basically the same as that of Example 2, except that the addition amounts of α-amylase and transglucosidase are 100U / starch dry weight (g) and 200U / starch dry weight (g), respectively. Figure 1 .

[0025] Comparative Example 2 The difference from the preparation method of Example 2 is that α-amylase is not added, and the other conditions are all the same.

[0026] Examples 2, 4, 5 and Comparative Example 2 investigated the effects of different amounts of α-amylase added on the products of resistant dextrin. The results are shown in Table 2.

[0027] Table 2: As shown in Table 2, with the increase of the amount of α-amylase added, the α-1,4 glycosidic bond in the resistant dextrin structure is significantly reduced, and the α-1,6 glycosidic bond content increases significantly. In Comparative Example 2, no α-1,4 glycosidic bond is added, only transglucosidase and branched glycosyltransferase are added, and there is no obvious branching degree of resistant dextrin, indicating that α-1,4 glycosidic bond is a prerequisite for transglucosidase and branched glycosyltransferase to play a role.

[0028] Comparative Example 3 The difference from Example 5 is that no branched glycosyltransferase was added, and the other conditions were all the same.

[0029] Example 5 and Comparative Example 3 investigated the effects of different amounts of added branched glycosyltransferase on the products of resistant dextrin. The results are shown in Table 3.

[0030] Table 3: As shown in Table 3, the addition of branched glycosyltransferase can improve the branching structure of resistant dextrin. In Example 5, the proportion of α-1,4 glycosidic bonds is 54.74%, while the proportion of α-1,4 glycosidic bonds in Comparative Example 3 is 56.68%, indicating that after adding branched glycosyltransferase, the branching degree of resistant dextrin can be increased while reducing the α-1,4 glycosidic bonds.

[0031] Example 6 The difference between Example 6 and Example 5 is that the starch used is wheat starch, and the other conditions are exactly the same. The nuclear magnetic resonance spectrum of the resistant dextrin prepared in Example 6 can be found at Figure 1 .

[0032] Example 7 The difference between Example 7 and Example 5 is that the starch used is pea starch, and the other conditions are exactly the same. The nuclear magnetic resonance spectrum of the resistant dextrin prepared in Example 7 is shown in Figure 1 .

[0033] Example 8 The difference between Example 8 and Example 5 is that the starch used is cassava starch, and the other conditions are exactly the same. The nuclear magnetic resonance spectrum of the resistant dextrin prepared in Example 8 is shown in Figure 1 .

[0034] The glycosidic bond distribution inside the resistant dextrins prepared in Examples 5 to 8 is shown in Table 4: Table 4: Among the four samples, pea resistant dextrin has the least α-1,4 glycosidic bonds, which is 47.44%. The α-1,4 bonds in corn resistant dextrin, wheat resistant dextrin and cassava resistant dextrin are quite different from those in pea resistant dextrin, indicating that the main chain structure is destroyed and a large-scale rearrangement occurs during the transformation of pea starch into resistant dextrin, forming a multi-branched structure. The content of branched starch in pea starch is as high as more than 60%, and starch with low amylose content itself has more α-1.6 bonds, which may hinder the hydrolysis of the α-1,4 bonds of the main chain by amylase, and also affect the subsequent transglycosylation and repolymerization process, so a part of the α-1,4 bonds is retained. Although resistant dextrin still has about 50% α-1,4 bonds, it has a strong resistance to digestion, which may be due to steric hindrance.

[0035] The above description is only used to explain the preferred embodiments of the present invention. In Example 5, 100 U / starch dry weight (g) α-amylase, 200 U / starch dry weight (g) transglucosidase and 200 U / starch dry weight (g) branched glycosyltransferase are determined to be the optimal preparation conditions. In the embodiment, pea starch is the optimal starch source for preparing resistant dextrin.

[0036] The present invention uses corn, wheat, pea and cassava starch as raw materials, controls the addition amount of α-amylase and transglucosidase to prepare resistant dextrins from different starch sources. Compared with the traditional acid-heat method, the present invention adds transglucosidase and branched glycosyltransferase during the preparation process, which can effectively reduce α-1,4 glycosidic bonds, increase α-1,6 glycosidic bonds and other non-starch glycosidic bonds, increase the branching structure of resistant dextrin, and improve the resistance components of resistant dextrin. The present invention uses different starches to prepare resistant dextrin, and can find out high-quality starch sources for preparing resistant dextrin.

Claims

1. A method for preparing resistant dextrins from different starch sources, characterized in that: The following steps are involved: S1, after starch is dissolved in distilled water, hydrochloric acid is added to the starch solution for acidification and filtration, and then dried to obtain acidified starch; S2, placing the acidified starch at high temperature to react to obtain pyrodextrin; S3, dissolving the pyrodextrin in water, adding α-amylase to the pyrodextrin solution, heating it in a water bath, then adding transglucosidase and branched glycosyltransferase, and continuing the reaction to obtain an enzymolysis solution; S4. Add ethanol solution to the enzymatic hydrolyzate for alcohol precipitation to obtain resistant dextrin.

2. The method for preparing resistant dextrins from different starch sources according to claim 1, characterized in that: In step S1, the addition ratio of starch and distilled water is limited to 10g starch: 15mL distilled water; The concentration of the hydrochloric acid is 0.5 mol / L, and the ratio of the hydrochloric acid solution to distilled water is 1:

15.

3. The method for preparing resistant dextrins from different starch sources according to claim 1, characterized in that: In step S1, the drying temperature is 70°C, and the water activity of the acidified starch is lower than 0.

1.

4. The method for preparing resistant dextrins from different starch sources according to claim 1, characterized in that: In the step S2, the acidified starch is heated at 170° C. for 3.5 hours to obtain pyrodextrin.

5. The method for preparing resistant dextrins from different starch sources according to claim 1, characterized in that: In step S3, the addition ratio of pyrodextrin and distilled water is limited to 5 g pyrodextrin: 10 mL distilled water.

6. The method for preparing resistant dextrins from different starch sources according to claim 1, characterized in that: The addition amount of the α-amylase is 20-100 U / starch dry weight (g); The added amount of the transglucosidase is 50-200 U / starch dry weight (g); The addition amount of branched glycosyltransferase was 200 U / starch dry weight (g).

7. The method for preparing resistant dextrins from different starch sources according to claim 1, characterized in that: The water bath heating condition was 70°C for 2 h; the subsequent reaction temperature was 56°C for 16 h.

8. The method for preparing resistant dextrins from different starch sources according to claim 1, characterized in that: In the step S4, the ethanol solution is 95% ethanol, the volume ratio of the ethanol solution to the enzymatic hydrolysate is 1:1, and the resistant dextrin is obtained after 4 alcohol precipitations.

9. The method for preparing resistant dextrins from different starch sources according to claim 1, characterized in that: The starches are corn, wheat, pea and tapioca starch.

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