CN-121991415-A - Structure-reinforced starch-based aerogel with improved porosity as well as preparation method and application thereof

Abstract

The invention discloses a structure-enhanced starch-based aerogel for improving porosity, a preparation method and application thereof, wherein the aerogel comprises enzyme modified starch and natural starch, the enzyme modified starch is obtained by adopting a complex enzyme system formed by a plurality of amylase to improve the natural starch. The method comprises the steps of S1, modifying natural starch through a composite enzyme system to obtain enzyme modified starch, S2, mixing the enzyme modified starch and the natural starch according to a proportion, adding water to form a composite suspension, carrying out gelatinization treatment to obtain a gelatinized starch system, and S3, carrying out gelatinization, freezing and drying treatment to the gelatinized starch system to obtain aerogel. The aerogel can be used in a thermal insulation material, an adsorption material, a biological-based structural material or a functional porous material. The molecular structure of the starch is controllably regulated through the synergistic effect of different enzyme systems, so that the porosity, structural uniformity and mechanical stability of the aerogel are obviously improved on the premise of not introducing a chemical cross-linking agent.

Inventors

• YANG JIN
• ZHAO XIANGJIE
• HUANG XINRUI
• QIN KAILI
• YANG RONGLING
• SHAO CANCAN
• LI YANG

Assignees

• 淮阴工学院

Dates

Publication Date

20260508

Application Date

20260214

Claims (10)

1. 1. The structure-enhanced starch-based aerogel with improved porosity is characterized by comprising enzyme modified starch and natural starch, wherein the enzyme modified starch is obtained by improving the natural starch by adopting a composite enzyme system formed by a plurality of amylase.
2. 2. The enhanced porosity, structurally reinforced, starch-based aerogel according to claim 1, wherein the mass ratio of enzyme modified starch to native starch is (0.5-4): 9.5-6.
3. 3. The enhanced porosity, structurally reinforced starch-based aerogel according to claim 2, wherein the complex enzyme system is a two-enzyme synergistic system or a three-enzyme synergistic system, the two-enzyme synergistic system being a combination of an alpha-amylase and a dextrinase, or a combination of an alpha-amylase and a pullulanase, the three-enzyme synergistic system comprising at least an alpha-amylase, a dextrinase and a glucoamylase.
4. 4. The enhanced porosity, structurally reinforced starch-based aerogel of claim 2, wherein the native starch is one or more of canna starch, corn starch, wheat starch, potato starch, tapioca starch, pea starch, rice starch.
5. 5. The enhanced porosity, structurally reinforced, starch-based aerogel according to claim 2, further comprising structural reinforcement units comprising 2% -5% of the total dry basis mass of the enzyme modified starch and natural starch.
6. 6. The enhanced porosity structurally reinforced starch-based aerogel according to claim 5, wherein the structural reinforcement units comprise cellulose nanofibers and/or bacterial cellulose.
7. 7. A method for preparing the enhanced porosity structural starch-based aerogel according to claims 1-6, comprising the following specific steps: s1, modifying natural starch through a complex enzyme system to obtain enzyme modified starch; S2, mixing the enzyme modified starch and the natural starch according to a proportion, adding water to form a composite suspension, and heating to more than 95 ℃ to perform gelatinization treatment to obtain a gelatinized starch system; and S3, gelatinizing, freezing and drying the gelatinized starch system to obtain the aerogel.
8. 8. The method for preparing a structurally reinforced starch-based aerogel having increased porosity according to claim 7, wherein the structural reinforcement units are added in a water-dispersed form during the gelatinization process in step S2.
9. 9. The method for preparing a structurally reinforced starch-based aerogel having improved porosity according to claim 7, wherein the specific steps of step S1 are as follows: S11, dispersing natural starch in water to prepare a starch water dispersion system with the mass fraction of 5-20wt%; s12, adding a single enzyme system or a two-enzyme/three-enzyme synergistic modification system into the dispersion system under the stirring condition, and performing partial enzymolysis reaction under the mild condition, wherein the reaction temperature of the enzymolysis reaction is 40-55 ℃; the pH value is 4.5-5.5 during the reaction, and the reaction time is 4-10h.
10. 10. Use of a structurally reinforced starch-based aerogel of enhanced porosity according to claims 1-6 in a thermal insulation material, an adsorption material, a bio-based structural material or a functional porous material.

Description

Structure-reinforced starch-based aerogel with improved porosity as well as preparation method and application thereof Technical Field The invention relates to the technical field of bio-based porous materials, in particular to a structure-reinforced starch-based aerogel with improved porosity, a preparation method and application thereof. Technical Field Aerogels are a class of solid materials having a three-dimensional, continuous porous structure, generally exhibiting high porosity, low density, and large specific surface area. In recent years, along with the continuous promotion of green materials and sustainable development concepts, the preparation of bio-based aerogel by taking natural polymers as raw materials gradually becomes a research hot spot. The starch is used as a natural polysaccharide material which is wide in source, low in price, renewable and biodegradable, and has good application potential in the aerogel field. In the prior art, the starch-based aerogel is generally prepared through steps of starch dispersion, gelatinization, gelation, freeze drying and the like, and has potential application value in the fields of food contact packaging, adsorption and slow release carriers, heat insulation materials, biomedical materials and the like. However, starch-based aerogels still suffer from significant disadvantages in terms of structural stability and mechanical properties compared to inorganic aerogels or synthetic polymeric aerogels, limiting their further use. In particular, the aerogel constructed from the purely natural starch system is structurally weak. Natural starch is mainly composed of amylose and amylopectin, and the molecules thereof form a three-dimensional network structure by virtue of hydrogen bonding. Because the molecular chains have stronger rigidity and ordered structure, the gel network is easy to collapse or shrink in the freeze drying process, so that the pore size distribution is uneven, the pore wall is thinned and even broken, and the prepared aerogel often has the problems of limited porosity, higher density and insufficient mechanical strength, and is difficult to meet the requirements of light weight and structural stability. In the research, it was found that the porosity of the aerogel could be increased by enzymolysis, but the porosity was not uniform and the structure was severely collapsed, because the randomness of enzymolysis, the porosity increase did improve the density and the space property, but the mechanical property was reduced. In order to solve the problems, a part of the prior art carries out chemical modification on starch molecules by introducing a chemical crosslinking agent so as to improve the crosslinking density and structural stability of a gel network. For example, the mechanical properties of the aerogel can be improved to a certain extent by adopting crosslinking agents such as epichlorohydrin, glutaraldehyde and the like to treat the starch. However, such methods generally have the disadvantages that, on the one hand, chemical cross-linking agents have a certain toxicity, reaction byproducts or residues thereof are difficult to completely remove, migration may occur in food or pharmaceutical systems, and there is a safety hazard, and, on the other hand, chemical modification processes increase process complexity and environmental burden, which is unfavorable for the development of green and sustainable materials. The Chinese patent document CN111172221A discloses a preparation method and application of modified starch, which relate to the technical field of starch preparation, wherein beta-amylase is added into starch gelatinization liquid for modification, branching enzyme is added for continuous modification after enzyme deactivation, pullulanase is added for continuous modification after enzyme deactivation, enzymatic hydrolysate is subjected to alcohol precipitation after enzyme deactivation, and the precipitate is dried to obtain the modified starch. However, the prior art has uneven branching degree, insufficient crosslinking density and uneven distribution of functional groups, which may lead to uncontrollable degradation behavior of the material. In contrast, enzymatic modification has received attention in recent years as a mild, controllable and environmentally friendly means of modifying starch. The starch molecules are partially hydrolyzed by enzyme preparations such as alpha-amylase, so that partial crystal area structures can be destroyed, and the solubility and gelatinization performance of the starch are improved. However, the prior researches focus on enzymolysis modification of a single enzyme system, and the method often leads to excessive breakage of starch molecular chains, so that a formed gel network structure is loose, and sufficient mechanical strength is difficult to obtain while high porosity is maintained. In addition, in the prior art, few reports are about the technical proposal that the molecular stru