Toughening modification method of starch gel

Abstract

The invention provides a toughening modification method of starch gel, and relates to the technical field of starch processing. The toughening modification method provided by the invention comprises the following steps: soaking natural starch gel in a natural eutectic solvent, and separating to obtain toughened and modified starch gel. Solvent exchange is carried out between the natural eutectic solvent and water in the natural starch gel, so that a gel network is promoted to be subjected to microphase separation to improve the toughness of the starch gel, and further application of the natural starch gel in the food industry is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of starch processing, and particularly relates to a toughening modification method of starch gel. BACKGROUND

[0002] Starch is a natural polysaccharide widely existing in crops such as cereals and tubers, and has a wide source and low price. Starch is mainly composed of amylose and amylopectin, in which amylose is connected into linear molecules by alpha-1,4 glycosidic bonds, and amylopectin is highly branched. When starch is heated in water, starch granules swell by absorbing water, and the crystal structure is melted and amylose molecules are dissolved out. With the cooling of the starch solution, the dissolved amylose molecules are recombined by hydrogen bonds, and together with the swollen amylopectin, they form a starch hydrogel which encapsulates water molecules in it. Because the starch gel has a certain viscoelasticity, it is often used as a thickening agent, a stabilizer and a gelling agent in the food industry.

[0003] However, the gel three-dimensional network of natural starch gel is usually interwoven by strong hydrogen bond regions and weak hydrogen bond regions, and brittle fracture easily occurs when subjected to external force, which leads to poor toughness of the gel. Especially during storage, the continuous recrystallization of amylose molecules further strengthens the gel network, resulting in increased hardness and decreased toughness of the starch gel. These inherent defects seriously restrict the application of natural starch gel in the food industry. Therefore, it is urgent to provide a solution to improve the above problems. SUMMARY

[0004] The purpose of the present application is to provide a toughening modification method of starch gel, which promotes the microphase separation of the gel network by solvent exchange between natural deep eutectic solvent and water in the natural starch gel, thereby improving the toughness of the starch gel, and helps to improve the further application of natural starch gel in the food industry.

[0005] The present application provides a toughening modification method of starch gel, which comprises: soaking natural starch gel in natural deep eutectic solvent and then separating to obtain toughened and modified starch gel.

[0006] Optionally, the natural deep eutectic solvent comprises citric acid and D-sorbitol with a molar ratio of 1:1, lactic acid and D-(+)-glucose with a molar ratio of 5:1, and D-(+)-glucose and DL-malic acid with a molar ratio of 1:1.

[0007] Optionally, the natural starch gel is soaked in the natural deep eutectic solvent at 20-30 DEG C.

[0008] Optionally, the soaking in the natural deep eutectic solvent is for 0.5-2 hours.

[0009] Optionally, the natural starch gel is soaked in the natural deep eutectic solvent at a solid-liquid ratio of 0.2 g / mL-0.4 g / mL.

[0010] Optionally, the method for preparing the natural starch gel comprises: heating and gelatinizing the natural starch solution in a boiling water bath, and cooling to obtain the natural starch gel.

[0011] Optionally, the mass fraction of the starch in the natural starch solution is 15%-25%.

[0012] Optionally, the natural starch in the natural starch solution comprises one of corn starch, potato starch, cassava starch, and wheat starch.

[0013] Optionally, the heating and gelatinization is performed for 25 min-35 min.

[0014] Optionally, the cooling is performed for 0.1 h-2 h.

[0015] In a second aspect, the application further provides a high-toughness starch gel prepared by any of the above toughening modification methods. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Figure 1 is a diagram showing the shape and size of the starch gel in Example 1 and Comparative Example 1 of the application, which is subjected to tensile testing;

[0017] Figure 2 Figure 2 is a diagram showing the fracture state of the starch gel in Example 1 and Comparative Example 1 of the application, which is subjected to tensile testing;

[0018] Figure 3 Figure 3 is a diagram showing the microstructure of the starch gel in Example 1 and Comparative Example 1 of the application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme of the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are some embodiments of the application, rather than all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0020] The application provides a toughening modification method for a starch gel, which comprises: soaking a natural starch gel in a natural deep eutectic solvent, and separating the toughened and modified starch gel. In fact, when the natural starch gel is soaked in the natural deep eutectic solvent, the water wrapped in the natural starch gel can be exchanged with the natural deep eutectic solvent, thereby promoting the micro-phase separation of the natural starch gel, and effectively improving the toughness of the starch gel.

[0021] Specifically, the hydrogen bond donor and the hydrogen bond acceptor used in the natural deep eutectic solvent are both food-grade substances. Further, the natural deep eutectic solvent used includes citric acid and D-sorbitol in a molar ratio of 1:1, lactic acid and D-(+)-glucose in a molar ratio of 5:1, and D-(+)-glucose and DL-malic acid in a molar ratio of 1:1.

[0022] In some embodiments, the method for preparing the natural starch gel includes: heating and gelatinizing a natural starch solution in a boiling water bath and then cooling to obtain a natural starch gel. Specifically, the natural starch used includes one of corn starch, potato starch, tapioca starch, and wheat starch, and the mass fraction of the natural starch in the natural starch solution can be 15%-25%.

[0023] In some embodiments, the natural starch solution is heated and gelatinized in a boiling water bath for 25 min-35 min. Specifically, the heating treatment time during the heating and gelatinization process is long enough to completely gelatinize the natural starch. In addition, the natural starch gel is left to stand for 0.1 h-2.0 h after cooling to room temperature to improve the stability of the natural starch gel structure.

[0024] In some embodiments, the natural starch is added to the natural deep eutectic solvent at a solid-liquid ratio of 0.2 g / mL-0.4 g / mL and soaked for 0.5 h-2 h at 20℃-30℃ to perform the toughening modification.

[0025] Embodiment 1

[0026] The embodiment 1 provides a method for toughening modification of a starch gel, including:

[0027] S1, dispersing 20 g of corn starch in 100 mL of distilled water to obtain a natural starch solution, heating the natural starch solution in a boiling water bath for 30 min to completely gelatinize the starch, and then leaving the natural starch solution to stand at room temperature for 0.5 h to obtain a natural starch gel;

[0028] S2, mixing 192.13 g of citric acid and 182.17 g of D-sorbitol, heating and stirring in a 90℃ water bath environment for 1 h to obtain a uniform and clear natural deep eutectic solvent;

[0029] S3, immersing the starch gel in the natural deep eutectic solvent at a solid-liquid ratio of 0.2 g / mL, leaving the starch gel to stand at room temperature of 25℃ for 0.5 h, and then taking out to obtain a high-toughness starch gel.

[0030] Embodiment 2

[0031] This embodiment 2 provides a toughening modification method of starch gel, which is different from embodiment 1 in that, in step S2, after 90.08 g of lactic acid is mixed with 36.03 g of D-(+)-glucose and heated and stirred in a 90°C water bath environment for 1 h, a uniform and clear natural deep eutectic solvent is prepared; in step S3, after standing at room temperature of 25°C for 2 h, a high-toughness starch gel is taken out.

[0032] Embodiment 3

[0033] This embodiment 3 provides a toughening modification method of starch gel, which is different from embodiment 1 in that, in step S2, after 180.16 g of D-(+)-glucose and 134.09 g of DL-malic acid are mixed and heated and stirred in a 90°C water bath environment for 1 h, a uniform and clear natural deep eutectic solvent is prepared; in step S3, after standing at room temperature of 25°C for 1 h, a high-toughness starch gel is taken out.

[0034] Comparative Example 1

[0035] This comparative example 1 provides a preparation method of a natural starch gel, which comprises: dispersing 20 g of corn starch in 100 mL of distilled water to prepare a natural starch solution, heating the natural starch solution in a boiling water bath for 30 min to completely gelatinize the starch, and then standing at room temperature for 0.5 h to prepare a natural starch gel.

[0036] Performance detection

[0037] The high-toughness starch gel prepared in embodiment 1 and the natural starch gel prepared in comparative example 1 are subjected to tensile property testing, which comprises: respectively shaping the high-toughness starch gel and the natural starch gel into dumbbell shapes as shown in Figure 1 , clamping the two ends of the gel in the length direction using clamping arms in a TA-XTplus texture analyzer, and then recording the tensile distance at the time of gel fracture and taking a gel image at the time of fracture as shown in Figure 2 , and calculating the elongation at break of the gel.

[0038] As can be seen from Figure 2 , the natural starch gel prepared in comparative example 1 is fractured at a tensile distance of 7.5 mm, and the calculated elongation at break is 46.98% and the fracture stress is 11.23 g, while the high-toughness starch gel prepared in embodiment 1 is fractured at a tensile distance of 38.9 mm, and the calculated elongation at break is 388.73% and the fracture stress is 385.36 g, which shows that the high-toughness starch gel provided by the present application can effectively improve the toughness of the gel.

[0039] Structural characterization is performed on the high-toughness starch gel prepared in embodiment 1 and the natural starch gel prepared in comparative example 1 as shown inFigure 3 It can be seen from FIG. 1 that the native starch gelatin (A) in Comparative Example 1 has a clear gel network structure, while the high-toughness starch gelatin (B) in Example 1 has no network structure, which indicates that the gel network can be changed and the toughness can be improved after the native starch gelatin is soaked in the deep eutectic solvent. Figure 3 Figure 3 Figure 3

[0040] While the embodiments of the present application have been described in detail above, it is apparent to those skilled in the art that various modifications and changes can be made to the embodiments without departing from the scope and spirit of the present application as described in the claims. Moreover, the present application described herein can have other embodiments and be practiced or implemented in various ways.​​​

Claims

1. A method for toughening and modifying starch gel, characterized in that, include: The toughened and modified starch gel was obtained by immersing the natural starch gel in a natural eutectic solvent and then separating it.

2. The toughening modification method according to claim 1, characterized in that, The natural eutectic solvents include citric acid and D-sorbitol in a molar ratio of 1:1, lactic acid and D-(+)-glucose in a molar ratio of 5:1, and D-(+)-glucose and DL-malic acid in a molar ratio of 1:

1.

3. The toughening modification method according to claim 1, characterized in that, The natural starch gel was soaked in a natural eutectic solvent at 20℃-30℃; and / or, soaked in a natural eutectic solvent for 0.5h-2h; and / or, the natural starch gel was soaked in a natural eutectic solvent at a solid-liquid ratio of 0.2g / mL-0.4g / mL.

4. The toughening modification method according to claim 1, characterized in that, The method for preparing the natural starch gel includes: heating a natural starch solution in a boiling water bath to gelatinize it and then cooling it to obtain a natural starch gel; preferably, the starch mass fraction in the natural starch solution is 15%-25%.

5. The toughening modification method according to claim 4, characterized in that, The natural starch in the natural starch solution includes one of corn starch, potato starch, cassava starch, and wheat starch; and / or, it is heated and gelatinized for 25 min-35 min; and / or, it is cooled and allowed to stand for 0.1 h-2 h.

6. A high-toughness starch gel prepared by the toughening modification method according to any one of claims 1 to 5.

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