A method for reducing the viscosity of potato starch

Abstract

This invention discloses a method for reducing the viscosity of potato starch, belonging to the fields of enzyme engineering and biomodified starch technology. This invention provides a method for preparing macrocyclodextrin by reacting starch with 4-α-glycosyltransferase, which is then added to potato starch to provide a suitable substrate for subsequent starch processing. This application in starch processing offers a new approach and has great potential and application prospects.

Description

Technical Field

[0001] This invention relates to a method for reducing the viscosity of potato starch, belonging to the field of enzyme engineering and biomodified starch technology. Background Technology

[0002] Potatoes, also known as spuds or yams, are now widely cultivated in over 150 countries and regions, and are a staple vegetable and grain crop in China. Potatoes provide a strong feeling of fullness and are widely enjoyed for their taste, largely due to the presence of potato starch. Potato starch is widely utilized because of its many unique properties. For example, its high viscosity makes it a common thickener; its high degree of polymerization (approximately 3000) and large particle size result in high swelling capacity and excellent water retention, making it suitable for puffed foods, meat products, and instant noodles. Furthermore, potato starch has low protein and fat residue, high phosphorus content, and a pure white color with natural phosphorescence, resulting in high solution transparency and improving the color and appearance of products. However, natural potato starch also has several drawbacks, such as easy aging, poor shear resistance, tendency to precipitate at low temperatures, and instability, which limit its application in practical industry. Modification treatment can significantly expand its application range. The viscosity of potatoes is actually one of the more important indicators among their many properties. Reducing viscosity while maintaining the sample's shear resistance is of great significance for expanding the applications of starchy foods, improving their performance, and meeting the requirements for healthy human consumption.

[0003] Typically, industry employs enzymatic, chemical, and physical modification methods to alter the physicochemical properties of natural starch, thereby improving its functional characteristics, meeting the demands of food processing, and expanding its applications. However, while chemical modification methods such as oxidation, cross-linking, etherification, and esterification introduce new chemical bonds to strengthen the molecular structure of native starch and partially improve its functional properties, they also cause significant environmental pollution and pose food safety risks. Enzymatic modification, due to its environmentally friendly and efficient advantages, is more favored in food processing.

[0004] 4-α-glycosyltransferase (4αGT, EC 2.4.1.25) is found in the glycoside hydrolase (GH) family of 13, 57, and 77. 4αGT exhibits four different types of reactions: disproportionation, cyclization, coupling, and hydrolysis. This enzyme catalyzes intramolecular glycosyltransferase reactions, i.e., the transfer of intramolecular dextran molecules to macrodextrins (cyclization). Macrodextrins, abbreviated as CA or LR-CD, are a general term for cyclic dextrans with a degree of polymerization greater than 9, linked by α-1,4 glycosidic bonds. Unlike other cyclodextrins, the structure of macrodextrins is not constant; it changes with changes in the guest molecule and solution state. This allows for more possibilities in their interaction with starch molecules, influencing starch gelatinization and gelation behavior. Summary of the Invention

[0005] The inventors have developed a method to reduce the viscosity of potato starch using macrocyclodextrin. This invention features a highly efficient preparation process, simple equipment, and excellent product results. The method described in this invention provides a way to reduce the viscosity of potato starch, and it is easy to operate, allowing for the production of potato starch with reduced viscosity in a short time. This makes it suitable for preparing sauces, salads, and other products, thus broadening its application range.

[0006] This invention first uses potato starch as raw material, adds an appropriate amount of 4-α-glycosyltransferase, selects a suitable addition amount and reaction time to produce macrocyclodextrin. After enzyme inactivation treatment, it is then treated with β-amylase and pullulanase for a period of time, followed by alcohol precipitation and drying to obtain the target product, macrocyclodextrin. Adding the prepared macrocyclodextrin to potato starch and gelatinizing it together can quickly yield potato starch with reduced viscosity.

[0007] The first objective of this invention is to provide a simple method for preparing macrocyclodextrin, wherein the method involves adding 4-α-glycosyltransferase to starch to react with starch, performing enzyme inactivation treatment after the reaction is completed, and then treating with β-amylase and pullulanase for a period of time, followed by alcohol precipitation and drying to obtain the target product macrocyclodextrin.

[0008] In one embodiment of the present invention, the amount of the 4-α-glycosyltransferase is 5-40 U / g. 淀粉 .

[0009] In one embodiment of the present invention, the amount of pullulanase used is 50-500 U / g. 淀粉， The amount of β-amylase added is 10-100 U / g. 淀粉 .

[0010] In one embodiment of the present invention, the reaction temperature is 68-95°C.

[0011] In one embodiment of the present invention, the reaction time of the 4-α-glycosyltransferase is 0.5-12 h.

[0012] In one embodiment of the present invention, the reaction time of the β-amylase and pullulanase is 4-24 h.

[0013] In one embodiment of the present invention, the alcohol precipitation is performed using ethanol, and the ratio of the reaction solution to ethanol is 1:1 to 1:10.

[0014] In one embodiment of the present invention, the drying method includes freeze drying, atmospheric pressure drying, spray drying, drum drying, or microwave drying.

[0015] The present invention utilizes the above method to prepare macrocyclodextrin.

[0016] The second objective of this invention is to provide an application of macrocyclodextrin in rapidly reducing the viscosity of potato starch. This involves adding macrocyclodextrin to starch and gelatinizing it together to quickly obtain potato starch with reduced viscosity.

[0017] In one embodiment of the present invention, the application specifically involves adding macrocyclodextrin to starch, adding water to prepare a starch milk, and then performing gelatinization treatment.

[0018] In one embodiment of the present invention, the starch includes potato starch, corn starch, cassava starch, wheat starch, rice starch, and pea starch.

[0019] In one embodiment of the present invention, the starch milk has a mass fraction of 1-40%.

[0020] In one embodiment of the present invention, the amount of macrodextrin added to the starch is 1%-50% (dry basis percentage).

[0021] This invention relates to a macrocyclodextrin prepared using the above method.

[0022] This invention applies the above-mentioned macrocyclodextrin to the food, chemical, and pharmaceutical fields.

[0023] Beneficial Effects: This invention provides a method for preparing macrodextrin using 4-α-glycosyltransferase and its application in reducing the viscosity of potato starch. Adding 5% (dry basis) of macrodextrin resulted in a 57% decrease in the viscosity of gelatinized potato starch, demonstrating a significant effect. Potatoes have high viscosity and are difficult to stir; the addition of macrodextrin effectively reduces viscosity, greatly improving the application characteristics of potato starch and holding significant importance for its use in food processing. Attached Figure Description

[0024] Figure 1 TOF-MS identification diagram of macrodextrin preparation

[0025] Figure 2 : Effect of adding different amounts of macrodextrin on potato starch viscosity (Figure)

[0026] Figure 3 : Effect of adding macrodextrin and other substances on potato starch viscosity (Figure)

[0027] Figure 4 : Effect of macrocyclodextrin addition on the static rheology of potato starch gelatinization

[0028] Figure 5 Effect of macrocyclodextrin addition on the static rheology of potato starch after gelatinization and 1 day of storage.

[0029] Figure 6 Effect of macrocyclodextrin addition on the static rheology of potato starch after gelatinization and 5 days of storage. Detailed Implementation

[0030] Preparation of macrocyclodextrin: A certain amount of potato starch was weighed and dissolved in Tris-HCl buffer (50mM, pH 7.5) to prepare a 4% potato solution. The solution was gelatinized by stirring in a boiling water bath for 30 min. After the solution was evenly dispersed, it was cooled to the reaction temperature. 10 U / g starch 4-α-glycosyltransferase was added (the reaction solution without enzyme was used as a blank; the rest of the operation was the same). The reaction was carried out at 75℃ for 8 h, then stopped by heating in a boiling water bath for 30 min. The reaction solution was collected after centrifugation at 8000g for 15 min at 4℃. β-amylase (30 U / g starch) and pullulanase (100 U / g starch) were added to the reaction solution to remove unreacted amylose. The reaction was terminated by heating in a boiling water bath for 30 min at 42 °C. The precipitate was removed by centrifugation at 8000 g for 30 min, and the supernatant was collected. Four times the volume of ethanol was added to the reaction solution, and the mixture was left to stand overnight at 4 °C. The mixture was then centrifuged at 8000 × g for 15 min, and the precipitate was collected. The precipitate was rinsed with anhydrous ethanol, dialyzed with deionized water for 48 h, and then lyophilized to obtain the LR-CD sample.

[0031] Macrocyclodextrin was added to potato starch according to the dry basis percentage, and the effects on its gelatinization and rheological properties were studied.

[0032] Example 1: Effect of macrocyclodextrin addition on potato starch viscosity

[0033] Accurately weigh 2g of potato starch, add 5% macrodextrin (dry basis percentage), add deionized water to 27g, and prepare a suspension with a mass fraction of approximately 7%. Stir the sample until completely dissolved and place it in a rapid viscosity analyzer (RVA). According to national standards, use a heating-cooling cycle to gelatinize the sample.

[0034] Example 2: Effect of macrocyclodextrin on potato starch viscosity after addition of other substances

[0035] Accurately weigh approximately 1.56 g of potato starch, add 1% macrocyclodextrin (dry basis percentage), and add deionized water to a final volume of 26.5 g to prepare a suspension with a mass fraction of approximately 6%. After the sample is completely dissolved, place it in a rapid viscosity analyzer (RVA) and gelatinize the sample using a heating-cooling cycle, referring to national standards.

[0036] Example 3: Effect of macrocyclodextrin addition on the rheology of potato starch after gelatinization

[0037] A 6% (w / v) modified potato starch milk was prepared, in which macrocyclodextrin was added at a dry basis mass ratio of 1%, 2%, 5%, and 10%. The mixture was stirred in a 90°C water bath for 30 minutes and then poured into a disposable petri dish with a diameter of 100 mm and a height of 10 mm. After cooling to room temperature, the gel sample was evenly placed on the rheometer testing platform.

[0038] Depend on Figure 4 It can be seen that the addition of macrocyclodextrin has a significant decreasing effect on the viscosity of potato starch after gelatinization, and this effect is positively correlated with the amount added.

[0039] Example 4: Effect of macrocyclodextrin addition on rheology of potato starch 1 day after gelatinization

[0040] A 6% (w / v) modified potato starch milk was prepared, to which macrodextrin was added at dry weight ratios of 1%, 2%, 5%, and 10%. The mixture was stirred in a 90°C water bath for 30 min, then poured into disposable petri dishes with a diameter of 100 mm and a height of 10 mm. The mixture was then refrigerated at 4°C for 1 day to form a gel. The gel samples were then evenly placed on the rheometer testing platform.

[0041] Depend on Figure 5 It can be seen that after adding macrocyclodextrin, the viscosity of potato starch gelatinized and placed at 4°C for 1 day showed a significant decreasing trend, and this was positively correlated with the amount added.

[0042] Example 5: Effect of macrocyclodextrin addition on the rheology of potato starch after 5 days of gelatinization

[0043] A 6% (w / v) modified potato starch milk was prepared, to which macrodextrin was added at dry weight ratios of 1%, 2%, 5%, and 10%. The mixture was stirred in a 90°C water bath for 30 min, then poured into disposable petri dishes with a diameter of 100 mm and a height of 10 mm. The mixture was then refrigerated at 4°C for 5 days to form a gel. The gel samples were then evenly placed on the rheometer testing platform.

[0044] Depend on Figure 6It can be seen that after adding macrocyclodextrin, the viscosity of potato starch gelatinized and placed at 4℃ for 5 days showed a significant decreasing trend, and this was positively correlated with the amount added.

[0045] Comparative Example 1:

[0046] The specific steps are the same as in Example 1, except that the mass fraction of LR-CD added is 1% or 2%, while the other conditions remain unchanged, and the control is native starch.

[0047] Depend on Figure 2 It was found that the peak viscosity of potato starch decreased significantly after the addition of macrodextrin compared to the original potato starch. When the macrodextrin addition was 1%, 2%, and 5%, the peak viscosity of potato starch decreased by 21%, 35%, and 57%, respectively. Furthermore, with the increase of LR-CD addition, the viscosity of potato starch decreased significantly, both the peak viscosity and the trough viscosity. This indicates that during the gelatinization process of potato starch, macrodextrin participates in the amorphous arrangement and rearrangement of starch molecules, leading to a decrease in starch viscosity. Moreover, the retrogradation value decreases with increasing macrodextrin addition, which results in weak gelation ability after gelatinization and cooling.

[0048] Comparative Example 2:

[0049] Referring to Example 2, macrocyclodextrin was replaced with maltose, maltodextrin, α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, while other conditions remained unchanged. Native starch was used as the control.

[0050] Depend on Figure 3 The results showed that, compared with maltose, α-CD, β-CD, γ-CD, and maltodextrin (MD), the same amount of macrocyclodextrin LR-CD had a more significant effect on the viscosity of potato starch after gelatinization. The viscosity of the starch paste decreased with increasing LR-CD content. This may be because the starch structure is disrupted during gelatinization, and the starch molecules become disordered. Macrocyclodextrin participates in the rearrangement of starch chains; its flexible structure and relatively large cavities allow it to entangle with starch molecules, resulting in a decrease in starch paste viscosity.

[0051] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. An application of a macrocyclodextrin in reducing the peak viscosity of potato starch, characterized in that, Preparation of the macrocyclodextrin: Potato starch was dissolved in 50 mM, pH 7.5 Tris-HCl buffer to prepare a 4% potato solution. The solution was gelatinized by stirring in a boiling water bath for 30 min. After the solution was evenly dispersed, it was cooled to the reaction temperature. 10 U / g starch 4-α-glycosyltransferase was added. The reaction was carried out at 75℃ for 8 h, then stopped by heating in a boiling water bath for 30 min. The reaction solution was collected after centrifugation at 8000g for 15 min at 4℃. 30 U / g starch β-amylase and 100 U / g starch pullulanase were added to the reaction solution to remove unreacted linear starch. The powder was reacted at 42℃ for 8 hours, then heated in a boiling water bath for 30 minutes to terminate the reaction. The mixture was then centrifuged at 8000g for 30 minutes to remove the precipitate. The supernatant was collected, and 4 times its volume of ethanol was added to the reaction solution. The mixture was left to stand overnight at 4℃, centrifuged at 8000×g for 15 minutes, and the precipitate was collected. The precipitate was rinsed with anhydrous ethanol, dialyzed against deionized water for 48 hours, and then freeze-dried to obtain the final product. The application involves adding macrocyclodextrin to starch, adding water to prepare a starch slurry, and then performing gelatinization. The mass fraction of the starch slurry is 6%-7%, and the amount of macrocyclodextrin added to the starch is 1%-10% (dry basis).

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