CN113292746B - Method for preparing nanostarch by emulsification of amino starch and surfactant - Google Patents

Abstract

The invention discloses a method for preparing nano starch by emulsification of aminated starch and a surfactant, belonging to the technical field of modified starch development. Based on that amino is introduced into starch molecules and then dispersed in water to perform acid-base response, a surfactant is added into the dispersed phase, the generated hydration action forms a protective layer on the surface of the starch molecules to weaken the hydrogen bond acting force between the starch molecules, the electrostatic repulsion force and the hydrogen bond acting force between protonated amino groups inside the starch molecules reach an ideal state within a certain concentration range to granulate, and the granularity and the monodispersion state of nano starch particles can be regulated and controlled by controlling the factors such as the pH value of a system, the type of the surfactant and the like and assisting ultrasonic treatment. The method can control the particle size and the potential of the nano starch by the restrictive degradation and modification of the starch raw material, and prepare the nano particles with high monodispersity. The method for preparing the nano starch has the characteristics of short time consumption, high efficiency and environmental protection.

Description

Method for preparing nanostarch by emulsification of amino starch and surfactant

technical field

A method for preparing nano-starch based on the emulsification of aminated starch and surfactant, relates to controlled hydrolysis of starch, silane coupling to prepare amino starch, surfactant emulsification and electrostatic-hydrogen bond force balance to prepare nano-starch, belonging to The technical field of modified starch development.

Background technique

In recent years, nanoparticles have unique physical and chemical properties due to their high surface area and nanometer size, and are widely used in medicine, environment, and food fields. Depending on the source of raw materials, nanoparticles can be divided into two types: organic and inorganic. Inorganic nanoparticles such as lead, mercury, and tin are so hard and stable that they do not degrade easily, potentially leading to many environmental toxicities. In contrast, bioderived organic nanoparticles with good water solubility, biocompatibility, degradability, and edible properties have received increasing attention. Among them, starch has become an ideal nanoparticle raw material due to its wide source, rich functional groups that can be modified, and low price.

As a derivative of starch, nanostarch mainly includes starch nanocrystals and starch nanoparticles. Using sulfuric acid to hydrolyze the amorphous region of starch granules, starch nanocrystals can be obtained, but the long time and low yield limit its industrial application; However, the disadvantages of high energy consumption, non-uniform particle size and use of organic solvents are common.

Based on the above problems in the process of preparing nano-starch and the final product, the present invention introduces amino groups into starch molecules, blends with surfactants and prepares nano-starch granules through its emulsification, and the method is simple, rapid, mild and energy-consumption. lower, which can partially solve the problems in the preparation process of nanostarch.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a new method for rapidly and efficiently preparing nano-starch, so as to realize on-demand control of nano-starch particle size and potential.

The technical scheme of the present invention is as follows: a method for preparing nano-starch based on the emulsification of aminoated starch and surfactant, using waxy corn starch as a raw material, firstly controlling the molecular weight of starch by hydrolysis of pullulanase to obtain a paste with a certain molecular weight range N-aminoethyl-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane or γ-aminopropyltrimethoxysilane is used to prepare aminostarch by silane-coupling dextrin. Nano starch is prepared by reacting sodium dodecyl sulfate or sodium dodecyl sulfonate with amino starch.

A method for preparing nano-starch based on the emulsification of aminoated starch and surfactant, is carried out according to the following steps;

(1) Controlled hydrolysis of starch:

Prepare 10%-30% (w/v) waxy corn starch milk with pH=3-7 acetate buffer, gelatinize at 121°C for 30min, add pullulanase to hydrolyze after cooling, and the hydrolysis time is 6 ～24h, control the glucose equivalent (DE) value of the hydrolyzate to be 5～15, boil to kill the enzyme and cool it to normal temperature for standby use; the addition amount of pullulanase is 80～240NPUN/g starch;

(2) preparation of amino starch:

The silane coupling agent is added to the above-mentioned starch hydrolyzed solution, the addition amount is 1～5% (v/v), the pH of the system is adjusted with acetic acid=1～5, and the temperature is controlled to be 20～60°C, and the reflux reaction is performed for 1～5%. 5h, after the reaction was completed, the obtained amino starch solution was stirred overnight, and then freeze-dried; the freeze-dried samples were subjected to Soxhlet extraction with anhydrous ethanol as a solvent, and hot air drying was performed after 5 to 7 times of siphon phenomenon, and the temperature was controlled as 30～60 ℃; obtain amino starch.

(3) Preparation of nano-starch:

Amino starch is mixed with 0.1-0.5% (v/v) acetic acid solution to prepare a 0.1-1% (w/v) amino-starch solution, and the pH of the system is adjusted to 2-8 with NaOH. Mix the surfactant with the above solution, control the mass ratio of amino starch to the surfactant to be 2:1～8:1, and stir for 10～20min (100rpm); and then perform ultrasonic treatment on this solution, and the processing power is 50～ 150W, temperature 0°C, treatment for 2s, interval of 5s, treatment for 3-10min, the particle size of nanostarch was finally measured to be 80-500nm, and the surface potential was 20-40mV.

Wherein the silane coupling agent described in step (2) is KH792 (NH ₂ (CH ₂ ) ₂ NH(CH ₂ ) ₃ Si(OCH ₃ ) ₃ ) or γ-aminopropyltriethoxysilane or γ-aminopropylamine Propyltrimethoxysilane.

Wherein the surfactant described in step (3) is sodium dodecyl sulfate or sodium dodecyl sulfonate.

Beneficial effects of the present invention:

(1) By controlling the reaction amount of the amino groups in the amino starch, the control of the particle size of the nano-starch can be easily realized;

(2) The preparation of nano-starch with surfactant and amino starch has high efficiency and low energy consumption, and is easy to realize industrialization.

Detailed ways

Example 1

Prepare 10% (w/v) waxy corn starch milk with pH=3 acetate buffer, gelatinize at 121°C for 30min, add 240NPUN/g pullulanase for hydrolysis after cooling, hydrolysis time is 6h, control hydrolysis The DE value of the liquid is 5. After boiling to kill the enzyme, it is cooled to room temperature for use.

1% (v/v) silane coupling agent KH792 (NH ₂ (CH ₂ ) ₂ NH(CH ₂ ) ₃ Si(OCH ₃ ) ₃ ) was mixed and added to the hydrolyzed solution, and the pH of the system was adjusted with acetic acid=1 , and control the temperature to 60 ℃, reflux reaction for 5h, after the reaction is completed, the obtained amino starch solution is stirred overnight and freeze-dried; Soxhlet extraction is performed on amino starch with absolute ethanol as a solvent, and after 5 times of siphon phenomenon Hot air drying was performed, and the temperature was controlled to 30°C.

Amino starch (0.1%, w/v) was dissolved in 0.1% (v/v) acetic acid aqueous solution to prepare amino starch solution, and the pH of the system was adjusted to 2 with NaOH. And surfactant (sodium lauryl sulfate) and above-mentioned solution are mixed, stir (100rpm) 10min, control aminostarch and surfactant mass ratio to be 8:1; And then carry out ultrasonic treatment to this solution, processing power is 150W, temperature 0℃, treatment for 2s, interval of 5s, treatment for 10min, the particle size of nanostarch was measured to be 80nm, and the surface potential was 20mV.

Example 2

Prepare 30% (w/v) waxy corn starch milk with pH=7 acetate buffer, gelatinize at 121°C for 30min, add 80NPUN/g pullulanase for hydrolysis after cooling, hydrolysis time is 24h, control hydrolysis The DE value of the liquid is 15. After boiling to kill the enzyme, it is cooled to room temperature for use.

5% (v/v) silane coupling agent KH792 (NH ₂ (CH ₂ ) ₂ NH(CH ₂ ) ₃ Si(OCH ₃ ) ₃ ) was mixed and added to the hydrolyzed solution, and the pH of the system was adjusted with acetic acid=5 , control the temperature to 20 ℃, reflux reaction for 1h, after the reaction is completed, the obtained amino starch solution is stirred overnight, and freeze-dried; Soxhlet extraction is performed on the amino starch with absolute ethanol as a solvent, and the siphon phenomenon occurs 7 times. Hot air drying treatment, the temperature is controlled to 60 ℃.

Amino starch (1%, w/v) was dissolved in a 0.5% (v/v) acetic acid aqueous solution to prepare an amino starch starch solution, and the pH of the system was adjusted to 8 with NaOH. And surfactant (sodium dodecyl sulfonate) is mixed with above-mentioned solution, stirred 20min (100rpm), control aminostarch and surfactant mass ratio to be 2:1; And then carry out ultrasonic treatment to this solution, processing power It was 50W, the temperature was 0°C, the treatment was 2s, the interval was 5s, and the treatment was 3min. The particle size of the nanostarch was measured to be 500nm, and the surface potential was 40mV.

Claims (5)

1. A method for preparing nano starch based on emulsification of aminated starch and surfactant is characterized by comprising the following steps;

(1) starch controlled hydrolysis:

preparing 10-30% waxy corn starch milk by mass to volume ratio with an acetic acid buffer solution with pH = 3-7, gelatinizing for 30min at 121 ℃, cooling, adding pullulanase for hydrolysis for 6-24 h, controlling equivalent weight (DE value) of grapes in the hydrolysate to be 5-15, boiling to inactivate enzyme, and cooling to normal temperature for later use;

(2) preparation of amino starch:

adding a silane coupling agent into the starch hydrolysate, wherein the adding amount is 1-5% by volume, the pH of an acetic acid adjusting system is = 1-5, the temperature is controlled to be 20-60 ℃, reflux reaction is carried out for 1-5 h, the obtained amino starch solution is stirred overnight after the reaction is finished, and then freeze drying is carried out; carrying out Soxhlet extraction on a freeze-dried sample by taking absolute ethyl alcohol as a solvent, carrying out hot air drying treatment after 5-7 times of siphoning, and controlling the temperature to be 30-60 ℃; obtaining amino starch;

(3) preparing nano starch:

mixing amino starch with 0.1-0.5% by volume of acetic acid solution to prepare 0.1-1% by mass of amino starch solution, and adjusting the pH of the system to be 2-8 by NaOH; mixing a surfactant with the solution, controlling the mass ratio of the amino starch to the surfactant to be 2: 1-8: 1, and stirring at the rotating speed of 100rpm for 10-20 min; and then carrying out ultrasonic treatment on the solution to finally obtain the nano starch with the particle size of 80-500 nm and the surface potential of 20-40 mV.

2. The method for preparing nano starch based on the emulsification of aminated starch and surfactant according to claim 1, wherein the pullulanase in step (1) is added in an amount of 80-240 NPUN/g starch.

3. The method for preparing nano starch based on the emulsification of aminated starch and surfactant according to claim 1, wherein the silane coupling agent in step (2) is KH792 (NH)₂(CH₂)₂NH(CH₂)₃Si(OCH₃)₃) Or gamma-aminopropyltriethoxysilane or gamma-aminopropyltrimethoxysilane.

4. The method for preparing nano starch based on the emulsification of aminated starch and surfactant according to claim 1, wherein the surfactant in step (3) is sodium lauryl sulfate or sodium lauryl sulfate.

5. The method for preparing nano starch based on the emulsification of aminated starch and surfactant according to claim 1, wherein the ultrasonic treatment power in step (3) is 50-150W, the temperature is 0 ℃, the treatment time is 2s, the interval is 5s, and the treatment time is 3-10 min.