A method for preparing a starch gel with high water retention and flowability

Abstract

This invention discloses a method for preparing starch gels with high water retention and flowability, belonging to the field of biomodified starch technology. The invention involves adding cyclodextrin and cyclodextrin hydrolase to starch. The cyclodextrin includes β-cyclodextrin and γ-cyclodextrin. The cyclodextrin hydrolase hydrolyzes the cyclodextrin into maltodextrin oligosaccharides of corresponding degrees of polymerization in the system, thereby altering the structure of the starch molecular chains during gel formation and storage, and improving the water retention and rheological properties of the starch gel. Therefore, this invention effectively improves the water retention and flowability of starch gels by adding cyclodextrin and cyclodextrin hydrolase to the substrate, which is of great significance in food manufacturing.

Description

Technical Field

[0001] This invention relates to a method for preparing a starch gel with high water retention and flowability, belonging to the field of biomodified starch technology. Background Technology

[0002] Natural starch is insoluble in water at room temperature. When heated and gelatinized, starch granules transform from an ordered crystalline state to a disordered state. During cooling, amylose and amylopectin recombine into an ordered structure, macroscopically manifesting as the formation of a gel. Starch gel is a multidimensional network structure formed by the interconnected starch molecules; it is a special form of colloid, with properties between those of a solid and a liquid. Starch gels are widely used in food; for example, vermicelli, rice noodles, and rice vermicelli are traditional foods produced using the properties of starch gel, and these foods are popular with consumers. The water retention and flowability of starch gels are important factors determining food processing methods, and also affect the texture and sensory properties of the finished product. Therefore, adopting effective methods to improve the water retention and flowability of starch gels is of great significance in food manufacturing.

[0003] Currently, methods for improving the water retention and flowability of starch gels mainly include physical, chemical, and enzymatic methods. Enzymatic methods are favored due to their high efficiency, specificity, and environmental friendliness. Enzymes currently used to improve the texture of starchy foods mainly include α-amylase and maltodextrinase. α-amylase has strong random hydrolytic activity, easily leading to excessive hydrolysis of starch and destruction of the original texture of the food. Maltodextrinase, on the other hand, suffers from limitations such as a limited variety of available enzymes and high cost. Therefore, discovering other enzymes that can be used to improve the texture of starchy foods for preparing starch gels with high water retention and flowability is of great significance. Summary of the Invention

[0004] To address the aforementioned problems, this invention adds cyclodextrin and cyclodextrin hydrolase to starch. The cyclodextrin hydrolase hydrolyzes cyclodextrin into maltodextrin of the corresponding degree of polymerization in the system, thereby altering the structure of the starch molecular chain during starch gel formation and preservation, and improving the water retention and rheological properties of the starch gel.

[0005] The first objective of this invention is to provide a method for preparing a starch gel with high water retention and flowability. The method involves dispersing cyclodextrin in a buffer solution, reacting it with cyclodextrin hydrolase, then adding water and starch, mixing evenly, stirring and heating to gelatinize, and then cooling and storing.

[0006] In one embodiment of the present invention, the cyclodextrin is specifically β-cyclodextrin or γ-cyclodextrin.

[0007] In one embodiment of the present invention, the cyclodextrin hydrolase is numbered WP_048164969.1 in NCBI.

[0008] In one embodiment of the present invention, during the reaction of cyclodextrin with cyclodextrin hydrolase, 2-4 U of cyclodextrin hydrolase is added for every 100 mg of cyclodextrin.

[0009] In one embodiment of the present invention, the reaction temperature of the cyclodextrin and cyclodextrin hydrolase is controlled at 50-80°C, and the reaction time is controlled at 1-12h.

[0010] In one embodiment of the present invention, the amount of water and starch added is 1000-1800 mg of starch per 10 ml of water.

[0011] In one embodiment of the present invention, the amount of starch added corresponding to every 100 mg of cyclodextrin is 1000-2000 mg.

[0012] In one embodiment of the present invention, the starch is specifically corn starch, potato starch, cassava starch, sweet potato starch, pea starch, wheat starch, rice starch, mung bean starch, red bean starch, lotus seed starch, or chestnut starch.

[0013] In one embodiment of the present invention, the temperature during starch gelatinization is controlled at 90-100°C and the heating time is 30-90 min.

[0014] In one embodiment of the present invention, the stirring speed during starch gelatinization is 300-1000 r / min.

[0015] In one embodiment of the present invention, the buffer solution used in the method is a phosphate buffer solution.

[0016] In one embodiment of the present invention, the pH of the buffer solution is 4-10.

[0017] In one embodiment of the present invention, the method involves dispersing 100 mg of β-cyclodextrin in a buffer solution, adding 3.32 U of cyclodextrin hydrolase, and reacting at 70°C for 3 hours. Starch solution is then added, mixed thoroughly, stirred, heated to gelatinize, and then cooled for storage. The amount of cyclodextrin hydrolase added is specified; the buffer solution is a phosphate buffer with a pH of 6.0; the gelatinization conditions are magnetic stirring at 95°C, a rotation speed of 500 r / min, and constant temperature heating for 60 minutes.

[0018] In one embodiment of the present invention, the method involves dispersing 100 mg of γ-cyclodextrin in a buffer solution, adding 3.32 U of cyclodextrin hydrolase, and reacting at 70°C for 3 hours. A starch solution is then added, mixed thoroughly, stirred, heated to gelatinize, and then cooled for storage. The amount of cyclodextrin hydrolase added is specified; the buffer solution is a phosphate buffer with a pH of 6.0; the gelatinization conditions are magnetic stirring at 95°C, a rotation speed of 500 r / min, and constant temperature heating for 60 minutes.

[0019] A second objective of this invention is to provide a modified starch gel with high water retention and flowability.

[0020] In one embodiment of the present invention, the modified starch gel is obtained by reacting cyclodextrin and cyclodextrin hydrolase, then adding it to a starch solution, mixing it evenly, heating to gelatinize, and then cooling and storing it.

[0021] In one embodiment of the present invention, the cyclodextrin is specifically β-cyclodextrin or γ-cyclodextrin.

[0022] A third objective of this invention is to provide an application of the above-mentioned modified starch gel in the production of starch-based foods.

[0023] In one embodiment of the present invention, the starch-based food includes vermicelli, rice noodles, rice sheets, and rice vermicelli.

[0024] A fourth objective of this invention is to provide an application of the above-described preparation method in improving the water retention and flow properties of starch gels.

[0025] Beneficial effects:

[0026] This invention improves the water retention and flow properties of starch gels. Adding β-cyclodextrin and cyclodextrin hydrolase, and γ-cyclodextrin and cyclodextrin hydrolase to starch as a substrate, respectively, increased the water retention of the samples, reaching 125.12% and 126.7% of that of the original starch, respectively, significantly better than samples with cyclodextrin added alone. From a rheological perspective, the storage modulus and loss modulus of the modified starch gel decreased, while the loss angle increased, indicating enhanced flowability and a greater degree of viscosity observed in the experiments. Attached Figure Description

[0027] Figure 1 This is a component analysis diagram of the system in Comparative Example 1.

[0028] Figure 2 The images show the state of the sample gels after 1 day of storage. From left to right, they are Comparative Example 2, Comparative Example 3, Example 1, Example 2, and Example 3.

[0029] Figure 3The images show the state of the sample gels after 3 days of preservation. From left to right, they are Comparative Example 2, Comparative Example 3, Example 1, Example 2, and Example 3.

[0030] Figure 4 The images show the state of the gel samples after 7 days of storage. From left to right, they are Comparative Example 2, Comparative Example 3, Example 1, Example 2, and Example 3.

[0031] Figure 5 The graph shows the results of low-field NMR testing of the sample gel. The horizontal axis represents the relaxation time T2 (ms), and the vertical axis represents the signal amplitude.

[0032] Figure 6 The image shows the results of low-field NMR testing of the sample gel.

[0033] Figure 7 The image shows the results of the gel rheology test on the sample. Detailed Implementation

[0034] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0035] The materials involved in the following embodiments are as follows:

[0036] α-Cyclodextrin, β-cyclodextrin, and γ-cyclodextrin were purchased from Aladdin Reagent (Shanghai) Co., Ltd.; the expression host and vector used for cyclodextrin hydrolase were purchased from BGI Genomics (Beijing) Co., Ltd.; and wheat starch was purchased from Hangzhou ProStar Starch Co., Ltd.

[0037] The specific methods for determining the water retention of starch gels involved in the following examples are as follows:

[0038] The water-holding capacity of starch gel was characterized by low-field NMR analysis. The transverse relaxation time T2 of the sample gel was determined using a CPMG pulse sequence on a low-field NMR spectrometer. The specific measurement procedure was as follows: echo time 0.401 ms, 8 cumulative pulses, 1024 sampling points, and relaxation decay time 1000-2000 ms. The obtained data were normalized using the instrument's built-in software, and T2 and T3 were obtained by fitting the data with the following single-exponential and composite-exponential models. 21 T 22 T 23 Parameters such as these.

[0039] Single exponential model:

[0040] Composite index model:

[0041] The specific methods for determining the rheological properties of starch gels involved in the following examples are as follows:

[0042] Experiments were conducted using a rotational rheometer. The linear viscoelastic region of the sample gel was determined by strain scanning. Within this region, appropriate strain values ​​were selected, followed by frequency scanning. Gel properties were investigated using elastic modulus (G), viscous modulus (G''), and loss angle. In the experiment, a 40 mm diameter plate was used as the mold, with a controlled gap of 1000 μm. The strain scanning conditions were: frequency of 1 rad / s, temperature of 30 °C, and strain range of 0.1%–100%. The frequency scanning conditions were: strain within the linear viscoelastic region, temperature of 30 °C, and frequency range of 0.1–100 rad / s.

[0043] Example 1:

[0044] 100 mg of α-cyclodextrin was dispersed in 1.8 mL of phosphate buffer (pH 6.0), and 0.2 mL (3.32 U) of cyclodextrin hydrolase was added. The mixture was reacted at 70 °C for 3 h. Then, 13 mL of ultrapure water and 1400 mg of wheat starch were added, mixed thoroughly, and placed in a magnetic stirrer. The temperature was set to 95 °C and the stirring speed to 500 rpm. The mixture was heated at this constant temperature for 60 min to gelatinize. After cooling, the mixture was stored at 4 °C for 7 days.

[0045] Example 2:

[0046] 100 mg of β-cyclodextrin was dispersed in 1.8 mL of phosphate buffer (pH 6.0), and 0.2 mL (3.32 U) of cyclodextrin hydrolase was added. The mixture was reacted at 70 °C for 3 h. Then, 13 mL of ultrapure water and 1400 mg of wheat starch were added, mixed thoroughly, and placed in a magnetic stirrer. The temperature was set to 95 °C and the stirring speed to 500 rpm. The mixture was heated at this constant temperature for 60 min to gelatinize. After cooling, the mixture was stored at 4 °C for 7 days.

[0047] Example 3:

[0048] 100 mg of γ-cyclodextrin was dispersed in 1.8 mL of phosphate buffer (pH 6.0), and 0.2 mL (3.32 U) of cyclodextrin hydrolase was added. The mixture was reacted at 70 °C for 3 h. Then, 13 mL of ultrapure water and 1400 mg of wheat starch were added, mixed thoroughly, and placed in a magnetic stirrer. The temperature was set to 95 °C and the stirring speed to 500 rpm. The mixture was heated at this constant temperature for 60 min to gelatinize. After cooling, the mixture was stored at 4 °C for 7 days.

[0049] Comparative Example 1:

[0050] 100, 160, 200, 240, and 300 mg of α-cyclodextrin were dispersed in 1.8 mL of phosphate buffer (pH 6.0), and 0.2 mL (3.32 U) of cyclodextrin hydrolase was added. The mixture was reacted at 70 °C for 3 h. The samples were analyzed using a Waters Maldi Synapt Q-TOF MS system, a differential detector, and an APS-2 Hypersil amino column (250 mm × 4.6 mm, 5 μm). The mobile phase was 70% (v / v) acetonitrile solution, the flow rate was set to 0.8 mL / min, the injection volume was 20 μL, and the column temperature was maintained at 30 °C.

[0051] Comparative Example 2:

[0052] Dissolve 1500 mg of wheat starch in 15 mL of ultrapure water, mix well, and place in a magnetic stirrer. Set the temperature to 95℃ and the speed to 500 rpm. Heat at a constant temperature for 60 minutes to gelatinize. After cooling, store at 4℃ for 7 days.

[0053] Comparative Example 3:

[0054] Disperse 100 mg of glucose in 15 mL of ultrapure water, add 1400 mg of wheat starch, mix well, and place in a magnetic stirrer. Set the temperature to 95℃ and the speed to 500 rpm. Heat at a constant temperature for 60 min to gelatinize. After cooling, store at 4℃ for 7 days.

[0055] Comparative Example 4:

[0056] 100 mg of β-cyclodextrin was dispersed in 2 mL of phosphate buffer (pH 6.0) and reacted at 70 °C for 3 h. Then, 13 mL of ultrapure water and 1400 mg of wheat starch were added, mixed thoroughly, and placed in a magnetic stirrer. The temperature was set to 95 °C and the stirring speed to 500 rpm. The mixture was heated at this constant temperature for 60 min to gelatinize. After cooling, it was stored at 4 °C for 7 days.

[0057] Comparative Example 5:

[0058] 100 mg of α-cyclodextrin was dispersed in 2 mL of phosphate buffer (pH 6.0) and reacted at 70 °C for 3 h. Then, 13 mL of ultrapure water and 1400 mg of wheat starch were added, mixed thoroughly, and placed in a magnetic stirrer. The temperature was set to 95 °C and the stirring speed to 500 rpm. The mixture was heated at this constant temperature for 60 min to gelatinize. After cooling, it was stored at 4 °C for 7 days.

[0059] The results are as follows:

[0060] The results confirmed that maltohexasose was produced during the preparation of high water-holding and flowable starch gel using α-cyclodextrin as a raw material. Furthermore, under 3 hours of reaction, the system with a substrate concentration of 50 mg / mL exhibited the highest maltohexasose concentration. Therefore, selecting a substrate concentration of 50 mg / mL is reasonable for enzymatic reactions. Figure 1 ).

[0061] The gel formation process of the above samples was photographed during the preparation process, at times of storage of 1 day, 3 days, and 7 days, as shown below. Figure 2 , Figure 3 , Figure 4 As shown. (From left to right, they are Comparative Example 2, Comparative Example 3, Example 1, Example 2, and Example 3).

[0062] The water retention and rheological properties of different sample gels were determined according to the above method. The effect of adding α-cyclodextrin to Comparative Example 5 without adding cyclodextrin hydrolase was not significantly different from that of Example 1. Compared with Comparative Example 2, the relaxation times T2 of bound water and immobile water in Comparative Examples 3 and 4 were both reduced, indicating that water and starch in the system were more tightly bound, and the addition of glucose restricted the free movement of water. Simultaneously, the peak area of ​​immobile water decreased, indicating a reduction in water content. The relaxation times of the systems in Examples 1 and 2 remained essentially unchanged; the relaxation time of the sample in Example 3 decreased significantly, indicating that the free movement of water in the system was restricted, and the increased water content indicated enhanced water retention. Figure 5 ; Figure 6 The peak area of ​​non-flowing water in the sample was the largest, much higher than that of bound water and free water. Analysis of the non-flowing water content showed that Comparative Example 3 and Example 1 both decreased to varying degrees, Comparative Example 4 remained almost unchanged, while Examples 2 and 3 showed a significant increase. This indicates that the samples containing β-cyclodextrin and cyclodextrin hydrolase, and γ-cyclodextrin and cyclodextrin hydrolase, exhibited the greatest improvement in water retention, reaching 125.12% and 126.7% of the original starch, respectively. Furthermore, the effect was significantly better than that of samples with added glucose and samples with added β-cyclodextrin alone (Table 1).

[0063] Table 1 Summary of Low-Field NMR Data

[0064]

[0065] The loss tangent (Tanδ), also known as the loss factor, is the ratio of the loss modulus (G″) to the storage modulus (G′). It characterizes the relative strength of the viscous and elastic properties of a sample. A larger Tanδ value indicates a higher proportion of viscosity and stronger flowability, while a smaller value indicates a higher proportion of elasticity. The results show that compared to Comparative Example 2, the loss factors of Examples 1, 2, 3, and 3 are all increased, with the following effect: Example 3 > Example 2 > Comparative Example 3 > Example 1. Figure 7(Table 2). The results above indicate that, compared with the original starch gel, the modified starch gel exhibits more fluid properties, and the system shows more viscosity than elasticity.

[0066] Table 2. Loss angle variation in rheological testing.

[0067]

[0068] In summary, the method for preparing a high water-holding and flowable gel provided by this invention shows that the samples with the addition of β-cyclodextrin and cyclodextrin hydrolase and γ-cyclodextrin and cyclodextrin hydrolase to the substrate exhibit the greatest improvement in water retention, reaching 125.12% and 126.7% of the original starch, respectively, which is significantly better than the samples with cyclodextrin added alone. From a rheological perspective, the modified starch gels with the addition of β-cyclodextrin and cyclodextrin hydrolase and γ-cyclodextrin and cyclodextrin hydrolase show decreased storage modulus and loss modulus, while the loss angle increases significantly, indicating that the modified starch gels have enhanced flowability and exhibit more viscosity in the experiments.

[0069] 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. A method for preparing a starch gel with high water retention and flowability, characterized in that, The method involves dispersing β-cyclodextrin or γ-cyclodextrin in a buffer solution, reacting it with cyclodextrin hydrolase, then adding a starch solution, mixing thoroughly, stirring, heating to gelatinize, and cooling for storage. During the reaction between cyclodextrin and cyclodextrin hydrolase, 2-4 U of cyclodextrin hydrolase is added per 100 mg of cyclodextrin, the reaction temperature is 50-80℃, and the reaction time is 1-12 h.

2. The method according to claim 1, characterized in that, The buffer solution is a phosphate buffer solution with a pH of 4-10.

3. The method according to claim 1, characterized in that, In the method described, the amount of starch added corresponding to every 100 mg of cyclodextrin is 1000-2000 mg.

4. The method according to claim 1, characterized in that, The starch specifically refers to corn starch, potato starch, cassava starch, sweet potato starch, pea starch, wheat starch, rice starch, mung bean starch, red bean starch, lotus seed starch, or chestnut starch.

5. The method according to claim 1, characterized in that, During starch gelatinization, the temperature should be controlled at 90-100℃, the heating time at 30-90 minutes, and the stirring speed at 300-1000 r / min.

6. The method according to claim 1, characterized in that, The method involves dispersing β-cyclodextrin in a buffer solution, adding cyclodextrin hydrolase, reacting at 50-80℃ for 1-12 hours, adding starch solution, mixing thoroughly, stirring, heating to gelatinize, and then cooling and storing. The amount of cyclodextrin hydrolase added is 2-4 U per 100 mg of cyclodextrin. The buffer solution is a phosphate buffer with a pH of 4-10. The gelatinization conditions are a temperature controlled at 90-100℃, a heating time of 30-90 minutes, and a stirring speed of 300-1000 r / min.

7. A modified starch gel with high water retention and flowability, characterized in that, The modified starch gel is obtained by reacting cyclodextrin and cyclodextrin hydrolase according to the method described in claim 1, then adding it to a starch solution, mixing it evenly, heating to gelatinize, and then cooling and storing it.

8. The application of the modified starch gel according to claim 7 in the production of starch-based foods, characterized in that, The starch-based foods include vermicelli, rice noodles, rice sheets, and rice vermicelli.

9. The application of the method for preparing the high water retention and flowability starch gel according to any one of claims 1 to 6 in improving the water retention and rheological properties of starch gel.

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