Green process for the preparation of modified starches for replacing hydroxypropyl distarch phosphate

Abstract

The present application relates to starch production technical field, especially disclose a kind of green preparation method for modified starch for replacing hydroxypropyl distarch phosphate.The green preparation method, cassava starch is used as raw material, specifically includes the following steps: (1) cassava starch is mixed with water uniformly, and starch suspension is prepared;(2) adding alpha-amylase to starch suspension for glycosidic bond enzymolysis, then passivate enzyme activity;(3) the enzymatic hydrolysate is used to hexose oxidase and oligomeric glucan is subjected to lactonization reaction, then passivate enzyme activity;(4) the final enzymatic hydrolysate is centrifuged, washed with water, the precipitate is freeze-dried, and enzyme modified cassava starch is obtained.The paste viscosity, freeze-thaw stability, shear resistance, anti-aging and other chemical properties of the enzyme modified cassava starch prepared by the present application are close to or better than hydroxypropyl distarch phosphate, and the preparation process is simple, short cycle, green and safe, low in production cost, simple in equipment, suitable for industrial production, and safe and pollution-free during production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of starch production, and particularly relates to a green preparation method of modified starch for replacing hydroxypropyl distarch phosphate. BACKGROUND

[0002] China has very rich starch resources, and the total starch output in China in 2020 was 33.89 million tons. Starch as a food additive is based on its functional value for food processing, and provides certain properties required by food systems, such as shape or taste, thickening, gelling, adhesion and stability. In order to meet the processing or product requirements of a certain special food, the inherent properties of the original starch need to be controlled and modified to meet the needs of various special purposes. According to the structure and physicochemical properties of starch, chemical, physical or biological engineering methods are used to treat natural starch, so that it has properties suitable for a certain special purpose. Chemical modification method is widely used in food, medicine, material and other industries because it can significantly improve the physical and chemical processing performance of natural starch.

[0003] However, there are problems such as large amount of chemical reagents used in the process of manufacturing chemically modified starch, great harm of some chemical reagents (such as propylene oxide, acetic anhydride, etc.), difficulty in storage, unstable reaction, difficulty in treating wastewater, resulting in discontinuous production, serious environmental pollution, chemical reagent residues, food safety and other series of problems. Therefore, whether a better method can be found to replace chemically modified starch has become a research hotspot widely concerned at home and abroad in recent years.

[0004] Enzymatic modification is to treat starch with various enzyme preparations, so as to change the molecular size and structure of starch, chain length distribution and paste properties, etc. to form a specific granule or molecular form. However, there is almost no related research and product on the use of biological enzyme method to prepare green modified starch to replace chemically modified starch with stable properties, and it is still in a blank state.

[0005] Hydroxypropyl distarch phosphate is widely used in food industry, chemical industry and other fields as thickening agent, suspending agent and coating agent. The paste viscosity of hydroxypropyl distarch phosphate is stable, and it is particularly suitable for frozen food and instant food, so that the food has good water retention when stored at low temperature, and the heat resistance, acid resistance and shear resistance of the food can be enhanced. When used as thickening agent of meat juice, sauce, fruit juice and pudding, the food is smooth, thick, transparent, clear and free of particle structure, and has good freeze-thaw stability and boiling resistance, and good taste. However, as a chemically modified starch preparation, the preparation process of hydroxypropyl distarch phosphate is complex, the reaction is unstable, and the reaction reagent propylene oxide used is explosive, not easy to store, has great harm, and the generated wastewater is difficult to treat, which causes serious environmental pollution, and does not meet the sustainable development policy of China. Therefore, in order to replace hydroxypropyl distarch phosphate, the cassava starch is modified by using alpha-amylase and hexose oxidase complex enzyme method, and the high value-added, high performance, environmentally friendly and safe green enzyme modified starch which can replace hydroxypropyl distarch phosphate is developed, so as to promote the sustainable and healthy development of green modified starch industry in China. SUMMARY

[0006] In order to make up for the shortcomings of the prior art, the application provides a green preparation method of modified starch for replacing hydroxypropyl distarch phosphate, which has simple preparation process, safety, no pollution and low production cost.

[0007] The application is realized by the following technical scheme:

[0008] A green preparation method of modified starch for replacing hydroxypropyl distarch phosphate, which uses cassava starch as raw material and utilizes alpha-amylase and hexose oxidase for complex enzyme modification to prepare enzyme modified cassava starch, and specifically includes the following steps:

[0009] (1) uniformly mixing cassava starch and buffer solution, adjusting pH to prepare starch suspension;

[0010] (2) adding the starch suspension into alpha-amylase for glycosidic bond enzymolysis, and then passivating enzyme activity to obtain an enzyme solution;

[0011] (3) performing lactonization reaction on oligomeric dextran in the enzyme solution by using hexose oxidase, and then passivating enzyme activity to obtain a final enzyme solution;

[0012] (4) centrifuging and washing the final enzyme solution, freeze-drying the precipitate to obtain enzyme modified cassava starch.

[0013] The present application adopts alpha-amylase to partially hydrolyze the alpha-1,4-glycosidic bond inside starch, and the hydrolysis product is dextrin, oligomeric glucan, hexose sugar, etc.; then the hexose oxidase is used to oxidize the oligomeric glucan with different molecular weights under the condition of oxygen to generate the corresponding lactone substance; the chemical properties of the lactone mixture, such as paste viscosity, freeze-thaw stability, shear resistance, anti-aging, etc., are close to or better than hydroxypropyl distarch phosphate.

[0014] The more preferred technical scheme of the present application is:

[0015] In step (1), 10-30 g of starch is weighed, 200-400 mL of 0.01M sodium phosphate dibasic-sodium dihydrogen phosphate buffer solution is added to adjust the pH to 4.0-6.0, and the starch suspension is prepared by stirring in a 40-60℃ water bath.

[0016] Further preferably, 20 g of starch is weighed, 200 mL of sodium phosphate dibasic-sodium dihydrogen phosphate buffer solution is added to adjust the pH to 6.0, and the starch suspension is prepared by stirring in a 45℃ water bath.

[0017] In step (2), 2.5-5.5% of 20-40u / g of alpha-amylase based on the weight of the starch is added to the starch suspension, and the reaction is carried out for 30-120 min; then 1 mol / L sodium hydroxide solution is added to adjust the pH to 9-10 to terminate the enzyme reaction.

[0018] Further preferably, 5% of 20u / g of alpha-amylase based on the weight of the dry starch is added to the starch suspension, and the reaction is carried out for 30 min; then sodium hydroxide solution is added to adjust the pH to 9.5 to terminate the enzyme reaction.

[0019] In step (3), the pH of the enzyme solution is adjusted to 5.0-7.0 by using 0.01M sodium phosphate dibasic-sodium dihydrogen phosphate buffer solution, 1.5-5% of 20-60u / g of hexose oxidase based on the weight of the dry starch is added, and the reaction is carried out by stirring in a 20-40℃ water bath for 1-3h; after the reaction is completed, 1 mol / L sodium hydroxide solution is added to adjust the pH to 9-10 to terminate the enzyme reaction.

[0020] Further preferably, the pH of the enzyme solution is adjusted to 6.0, 5% of 20u / g of hexose oxidase based on the weight of the dry starch is added, and the reaction is carried out by stirring in a 25℃ water bath for 1h; after the reaction is completed, 1 mol / L sodium hydroxide solution is added to adjust the pH to 10 to terminate the enzyme reaction.

[0021] In step (4), after centrifugation of the final enzymatic hydrolysate at 5000-8000 rpm for 10-20 min, the precipitate is washed with three times the volume of water, and after washing three times, the precipitate is centrifuged again at 5000-8000 rpm for 10-20 min, and the precipitate is freeze-dried to obtain the enzyme-modified cassava starch.

[0022] Further preferably, after centrifugation of the final enzymatic hydrolysate at 8000 rpm for 10 min, the precipitate is washed with three times the volume of water, and after washing three times, the precipitate is centrifuged again at 6000 rpm for 10 min.

[0023] The present application is a green preparation method for replacing hydroxypropyl distarch phosphate, which uses a complex of alpha-amylase and hexose oxidase to modify cassava starch, solves various safety and environmental pollution problems that occur in the preparation process of chemically modified starch, and develops high-value, high-performance, environmentally friendly, safe green enzyme-modified starch that completely replaces hydroxypropyl distarch phosphate, which will promote the sustainable and healthy development of the green modified starch industry in China.

[0024] The enzyme-modified cassava starch prepared by the present application has chemical properties such as paste viscosity, freeze-thaw stability, shear resistance, and aging resistance that are close to or better than those of hydroxypropyl distarch phosphate, and has the advantages of simple preparation process, short cycle, green safety, low production cost, simple equipment, and suitability for industrial production, and is safe and pollution-free during production. BRIEF DESCRIPTION OF DRAWINGS

[0025] The present application will be further described below in conjunction with the accompanying drawings.

[0026] The present application will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 Appearance diagram of transparency and viscosity of 5% enzyme-modified starch paste and hydroxypropyl distarch phosphate paste

[0028] Figure 2 Appearance diagram of freeze-thaw stability of 5% enzyme-modified starch paste and hydroxypropyl distarch phosphate paste. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described in detail below in conjunction with specific examples, in order to facilitate the understanding of the present application, but are not limited to the present application.

[0030] Example 1: A green preparation method for modified starch that replaces hydroxypropyl distarch phosphate, which specifically includes the following steps:

[0031] (1) 20 g of cassava starch is weighed, 200 ml of 0.01 M sodium phosphate dibasic-sodium dihydrogen phosphate buffer is added to adjust the pH to 6.0, and the starch suspension is prepared by stirring in a 45℃ water bath.

[0032] (2) Add 1g of α-amylase (20u / g) and react for 30min. Then add 1mol / L sodium hydroxide solution to adjust the pH to 9.5 to terminate the reaction;

[0033] (3) Adjust the pH of the α-amylase hydrolysate to 6.0 using 0.01M disodium hydrogen phosphate-sodium dihydrogen phosphate buffer, add 1g of hexose oxidase (20u / g), and stir in a 25℃ water bath for 1h. After the reaction is complete, add 1mol / L sodium hydroxide solution to adjust the pH to 10 to terminate the reaction;

[0034] (4) After centrifuging the hexose oxidase hydrolysate in an 8000r centrifuge for 10 min, add three times the volume of water of the final hydrolysate to wash the precipitate. After washing three times with water, centrifuge again at 6000r for 10 min. After freeze-drying the centrifuged precipitate, enzyme-modified cassava starch with a yield of 89.24% was obtained.

[0035] The 5% enzyme-modified cassava starch paste prepared in this example had a peak viscosity of 552 cP and a freeze-thaw stability water absorption rate of 43.981%, while the 5% hydroxypropyl distarch phosphate paste had a peak viscosity of 515 cP and a freeze-thaw stability water absorption rate of 42.361%. Furthermore, the disintegration value (152 cP) of the enzyme-modified cassava starch paste, which characterizes the shear resistance of starch paste, was significantly higher than that of the hydroxypropyl distarch phosphate paste (47 cP), indicating that the enzyme-modified cassava starch paste has superior shear resistance. Conversely, the recovery value (167 cP) of the enzyme-modified cassava starch paste, which characterizes the aging degree of starch paste, was significantly lower than that of the hydroxypropyl distarch phosphate paste (302 cP), indicating that the enzyme-modified cassava starch paste has superior anti-aging ability compared to the hydroxypropyl distarch phosphate paste.

[0036] Example 2: A green preparation method for modified starch as an alternative to hydroxypropyl distarch phosphate, specifically including the following steps:

[0037] (1) Weigh 10g of cassava starch, add 200ml of 0.01M disodium hydrogen phosphate-sodium dihydrogen phosphate buffer to adjust the pH to 5.0, and place it in a 50℃ water bath and stir to prepare a starch suspension;

[0038] (2) Add 0.3g α-amylase (30u / g) and react for 60min. Then add 1mol / L sodium hydroxide solution to adjust the pH to 10 to terminate the enzyme reaction;

[0039] (3) Adjust the pH of the α-amylase hydrolysate to 5.8 using 0.01M disodium hydrogen phosphate-sodium dihydrogen phosphate buffer, add 0.3g of hexose oxidase (30u / g), and stir in a 35℃ water bath for 2h. After the reaction is complete, add 1mol / L sodium hydroxide solution to adjust the pH to 9 to terminate the enzyme reaction;

[0040] (4) The hexose oxidase enzyme solution was centrifuged in an 8000r centrifuge for 10 min, then the precipitate was washed with three times the volume of water, and the precipitate was washed three times with water and then centrifuged at 8000r for 10 min. The centrifugal precipitate was freeze-dried to obtain 85.18% yield of enzyme-modified cassava starch.

[0041] The 5% enzyme-modified cassava starch paste prepared in this example has a peak viscosity of 682cP, a freeze-thaw stability water absorption rate of 45.112%, a disintegration value (176cP), and a rebound value (207cP).

[0042] Example 3: A green preparation method of modified starch as an alternative to hydroxypropyl distarch phosphate, which specifically comprises the following steps:

[0043] (1) Weigh 30g of cassava starch, add 400ml of 0.01M disodium hydrogen phosphate-sodium dihydrogen phosphate buffer to adjust the pH to 4.0, and prepare a starch suspension in a 60°C water bath.

[0044] (2) Add 1.2g of α-amylase (40u / g) and react for 120min. Then add 1mol / L sodium hydroxide solution to adjust the pH to 10 to terminate the enzyme reaction;

[0045] (3) Adjust the pH of the α-amylase enzyme solution to 7.0 with 0.01M disodium hydrogen phosphate-sodium dihydrogen phosphate buffer, add 1.2g of hexose oxidase (50u / g), and stir in a 40°C water bath for 2h. After the reaction is completed, add 1mol / L sodium hydroxide solution to adjust the pH to 9 to terminate the enzyme reaction;

[0046] (4) The hexose oxidase enzyme solution was centrifuged in an 8000r centrifuge for 20 min, then the precipitate was washed with three times the volume of water, and the precipitate was washed three times with water and then centrifuged at 6000r for 10 min. The centrifugal precipitate was freeze-dried to obtain 80.65% yield of enzyme-modified cassava starch.

[0047] The 5% enzyme-modified cassava starch paste prepared in this example has a peak viscosity of 490cP, a freeze-thaw stability water absorption rate of 44.102%, a disintegration value (110cP), and a rebound value (174cP).

[0048] Comparative Example 1: A green preparation method of modified rice starch, which specifically comprises the following steps:

[0049] (1) Weigh 20g of rice starch, add 200ml of 0.01M disodium hydrogen phosphate-sodium dihydrogen phosphate buffer to adjust the pH to 6.0, and prepare a starch suspension in a 45°C water bath.

[0050] (2) Add α-amylase (20 u / g) and react for 30 min. Then add 1 mol / L sodium hydroxide solution to terminate the reaction by adjusting the pH to 9.5;

[0051] (3) Adjust the pH of the α-amylase enzyme solution to 6.0 by using 0.01M sodium phosphate dibasic-sodium phosphate buffer, add hexose oxidase (20 u / g), and place in a 25°C water bath for stirring reaction for 1 h. After the reaction is completed, add 1 mol / L sodium hydroxide solution to terminate the reaction by adjusting the pH to 10;

[0052] (4) After centrifugation of the hexose oxidase enzyme solution in an 8000r centrifuge for 10 min, wash the precipitate with three times the amount of water, wash three times with water, and then centrifuge at 6000r for 10 min again. After freeze-drying of the centrifugal precipitate, enzyme-modified rice starch with a yield of 82.98% is obtained.

[0053] The 5% enzyme-modified rice starch paste prepared in this example has a peak viscosity of 205 cP, a freeze-thaw stability water absorption rate of 69.332%, a disintegration value (123 cP), and a rebound value (84.00 cP).

[0054] Comparative Example 2: A green preparation method of modified pea starch, which specifically comprises the following steps:

[0055] (1) Take 20 g of pea starch, add 200 ml of 0.01M sodium phosphate dibasic-sodium phosphate buffer to adjust the pH to 6.0, and place in a 45°C water bath for stirring to prepare a starch suspension;

[0056] (2) Add α-amylase (20 u / g) and react for 30 min. Then add 1 mol / L sodium hydroxide solution to terminate the reaction by adjusting the pH to 9.5;

[0057] (3) Adjust the pH of the α-amylase enzyme solution to 6.0 by using 0.01M sodium phosphate dibasic-sodium phosphate buffer, add hexose oxidase (20 u / g), and place in a 25°C water bath for stirring reaction for 1 h. After the reaction is completed, add 1 mol / L sodium hydroxide solution to terminate the reaction by adjusting the pH to 10;

[0058] (4) After centrifugation of the hexose oxidase enzyme solution in an 8000r centrifuge for 10 min, wash the precipitate with three times the amount of water, wash three times with water, and then centrifuge at 6000r for 10 min again. After freeze-drying of the centrifugal precipitate, enzyme-modified pea starch with a yield of 86.11% is obtained.

[0059] The 5% enzyme-modified pea starch paste prepared in this example has a peak viscosity of 126 cP, a freeze-thaw stability water absorption rate of 72.636%, a disintegration value (7 cP), and a rebound value (56 cP).

[0060] Table 1 is the properties of enzyme modified cassava starch paste and hydroxypropyl distarch phosphate paste and freeze-thaw water absorption rate

[0061]

[0062] The present application uses alpha-amylase and hexose oxidase to prepare a green preparation method of enzyme modified cassava starch to replace hydroxypropyl distarch phosphate. The paste viscosity, freeze-thaw stability, shear resistance, anti-aging and other chemical properties of the prepared enzyme modified cassava starch are close to or better than those of hydroxypropyl distarch phosphate. Currently, the production of hydroxypropyl distarch phosphate requires propylene oxide, sodium trimetaphosphate, and a large amount of acid and alkali liquid, and the cost of reagents is about 3000 yuan / ton, while salt and other by-products are also produced. The alpha-amylase and hexose oxidase used in the present application cost about 3000 yuan / ton. In addition to the main product of enzyme modified cassava starch, only a small amount of by-products such as glucose, maltose, maltodextrin, and maltotriose are produced. The process is simple, green and safe, and the performance is stable.

[0063] In the above embodiments, the best mode of the present application is described. It is obvious that many changes can be made under the inventive concept of the present application. Here, it should be noted that any changes made under the inventive concept of the present application will fall within the scope of the present application.

Claims

1. A green process for the preparation of modified starches for replacement of hydroxypropyl distarch phosphate, characterized by: The application discloses a method for preparing enzyme modified cassava starch by using cassava starch as raw material and by means of complex enzyme modification of alpha-amylase and hexose oxidase. (1) uniformly mixing the cassava starch with a buffer solution, adjusting pH to prepare a starch suspension; (2) adding 2.5-5.5% of alpha-amylase based on the weight of the starch and 20-40 u / g to the starch suspension for glycosidic bond enzymolysis, and reacting for 30-120 min; then adding 1 mol / L sodium hydroxide solution to adjust pH to 9-10 to terminate the enzyme reaction, and obtaining an enzyme solution; (3) adjusting the pH of the enzyme solution to 5.0-7.0 by using 0.01M sodium phosphate dibasic-sodium phosphate monobasic buffer solution, adding 1.5-5% of hexose oxidase based on the weight of the starch and 20-60 u / g for lactonization reaction, stirring in a 20-40℃ water bath for 1-3h, adding 1 mol / L sodium hydroxide solution to adjust pH to 9-10 to terminate the enzyme reaction after the reaction is completed, and obtaining a final enzyme solution; (4) centrifuging the final enzyme solution, washing with water, freezing and drying the precipitate to obtain the enzyme modified cassava starch.

2. The method for green production of modified starch according to claim 1, characterized in that: In step (1), 10-30g of starch is weighed, 200-400mL of 0.01M sodium phosphate dibasic-sodium phosphate monobasic buffer solution is added to adjust pH to 4.0-6.0, and the starch suspension is prepared by stirring in a 40-60℃ water bath.

3. The method for green production of modified starch according to claim 1, characterized in that: In step (4), after the final enzyme solution is centrifuged at 5000-8000rpm for 10-20min, the precipitate is washed with three times the volume of water, and after washing for three times, the precipitate is centrifuged at 5000-8000rpm for 10-20min again; and the enzyme modified cassava starch is obtained by freezing and drying the precipitate after centrifugation.

4. The method for green production of modified starch according to claim 2, characterized in that: 20g of starch is weighed, 200mL of sodium phosphate dibasic-sodium phosphate monobasic buffer solution is added to adjust pH to 6.0, and the starch suspension is prepared by stirring in a 45℃ water bath.

5. The method of claim 1, wherein the modified starch is produced in a green state. 5% of alpha-amylase based on the weight of the starch and 20u / g are added to the starch suspension, and the reaction is carried out for 30min; then sodium hydroxide solution is added to adjust pH to 9.5 to terminate the enzyme reaction.

6. The method of claim 1, wherein the modified starch is produced in a green state. The pH of the enzyme solution is adjusted to 6.0, 5% of hexose oxidase based on the weight of the starch and 20u / g are added, the reaction is carried out by stirring in a 25℃ water bath for 1h, and 1 mol / L sodium hydroxide solution is added to adjust pH to 10 to terminate the enzyme reaction after the reaction is completed.

7. The method of claim 3, wherein the modified starch is produced in a green state. After the final enzyme solution is centrifuged at 8000rpm for 10min, the precipitate is washed with three times the amount of water, and after washing for three times, the precipitate is centrifuged at 6000rpm for 10min again.

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