Method for preparing electrospraying particles to improve stability of polyphenol

Abstract

This invention provides a method for preparing electrospraying particles to improve stability of polyphenol including the following steps: preparing a pectin-silica composite; adding polyphenolic compounds into the pectin-silica composite to prepare a core solution; and coaxial electrospraying the core solution and a shell solution to prepare electrospraying particles loaded polyphenol. This method utilizes a pectin-silica composite as a polyphenol loading carrier, improves the encapsulating efficiency of polyphenols, reduces the contact probability of polyphenols with oxygen and water, and improves the stability of polyphenols; and an acidic aqueous solution is used as a shell solution to synergize with the pectin-silica composite to further improve the stability of polyphenols.

Claims

1. A method for preparing electrospraying particles to improve stability of polyphenol comprising the following steps: preparing a pectin-silica composite; adding polyphenolic compounds into the pectin-silica composite to prepare a core solution; and coaxial electrospraying the core solution and a shell solution to prepare electrospraying particles loaded polyphenol.

2. The method for preparing the electrospraying particles to improve the stability of the polyphenol according to claim 1, wherein preparing the pectin-silica composite comprising the following steps: preparing a pectin solution: adding deionized water into pectin and stirring until the pectin is completely dissolved, and the pectin solution in an amount of 5%-10% by weight is prepared; preparing a silica suspension: adding the deionized water into a silica powder while stirring, and the silica suspension in an amount of 0.1%-0.5% by weight is prepared; and preparing the pectin-silica composite: adding the silica suspension in the amount of 0.1%-0.5% by weight into the pectin solution in the amount of 5%-10% by weight drop by drop while stirring, and the pectin-silica composite being obtained.

3. The method for preparing the electrospraying particles to improve the stability of the polyphenol according to claim 2, adding 0.1-0.5 g tea polyphenols into the pectin-silica composite and stirring, and the core solution being prepared.

4. The method for preparing the electrospraying particles to improve the stability of the polyphenol according to claim 1, wherein the shell solution is an acidic aqueous solution.

5. The method for preparing the electrospraying particles to improve the stability of the polyphenol according to claim 4, wherein the shell solution is the acidic aqueous solution of which pH is 4.

6. The method for preparing the electrospraying particles to improve the stability of the polyphenol according to claim 4, wherein the shell solution is an acetic acid solution in an amount of 5%-10%.

7. The method for preparing the electrospraying particles to improve the stability of the polyphenol according to claim 1, wherein electrospraying conditions comprise: electrostatic voltage: 16-18 kv; receiving distance: 13-16 cm; needle type of the core solution: inner diameter 0.6 mm, outer diameter 0.9 mm; needle type of the shell solution: inner diameter 0.12 mm, outer diameter 0.15 mm; room temperature: 20° C.-25° C.; and air humidity: 45%-65%.

8. The method for preparing the electrospraying particles to improve the stability of the polyphenol according to claim 1, comprising the following steps: preparing a pectin solution: adding deionized water into pectin and stirring until the pectin is completely dissolved, and the pectin solution in an amount of 10% by weight being prepared; preparing a silica suspension: adding the deionized water into a silica powder while stirring, and the silica suspension in an amount of 0.5% by weight being prepared; adding 0.5 g tea polyphenols into the pectin-silica composite and stirring for 2 hours in a magnetic stirrer, and the pectin-silica composite being prepared; and placing the pectin-silica composite on an electrospraying device as the core solution, taking an acetic acid solution in an amount of 10% by weight as the shell solution, and electrospraying particles loaded polyphenol being prepared; wherein electrospraying conditions comprise: electrostatic voltage: 18 kv; receiving distance: 16 cm; needle type of the core solution: inner diameter 0.6 mm, outer diameter 0.9 mm; needle type of the shell solution: inner diameter 0.12 mm, outer diameter 0.15 mm; room temperature: 25° C.; and air humidity: 65%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a preparation flowchart of an embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

(2) This invention is specifically described below with reference to the accompanying drawings and specific embodiments.

(3) As shown in FIG. 1, a method for preparing electrospraying particles to improve stability of polyphenol includes the following steps.

(4) Step One Prepare a Pectin-Silica Composite

(5) Preparing the pectin-silica composite includes the following steps: preparing a pectin solution: adding deionized water into pectin and stirring until the pectin is completely dissolved, and the pectin solution in an amount of 5%-10% by weight being prepared;

(6) preparing a silica suspension: adding the deionized water into a dry silica powder while stirring, and the silica suspension in an amount of 0.1%-0.5% by weight being prepared; and

(7) preparing a pectin-silica composite: adding the silica suspension in the amount of 0.1%-0.5% by weight into the pectin solution in the amount of 5%-10% by weight drop by drop while stirring, and the pectin-silica composite being obtained.

(8) Step Two add polyphenolic compounds into the pectin-silica composite to prepare a core solution. As one embodiment, polyphenolic compounds are tea polyphenols. Add 0.1-0.5 g tea polyphenols into the pectin-silica composite and stir, and the core solution is prepared. It should be noted that water-soluble polyphenols are applicable to this invention.

(9) Step Three coaxial electrospray the core solution and a shell solution to prepare electrospraying particles loaded polyphenol.

(10) As a preferred way, the shell solution is an acidic aqueous solution. Further preferably, the shell solution is the acidic aqueous solution of which pH is 4. As one embodiment, the shell solution is an acetic acid solution in an amount of 5%-10%.

(11) Electrospraying conditions include: electrostatic voltage: 16-18 kv; receiving distance: 13-16 cm; needle type of the core solution: inner diameter 0.6 mm, outer diameter 0.9 mm; needle type of the shell solution: inner diameter 0.12 mm, outer diameter 0.15 mm; room temperature: 20° C.-25° C.; and air humidity: 45%-65%.

(12) Principles:

(13) (1) In this invention, the pectin-silica composite is taken as the polyphenol loading carrier, the stability of polyphenols is improved by increasing the encapsulating efficiency of polyphenols and reducing the contact probability of polyphenols with oxygen and water.

(14) Specifically, due to the concentration of the solution used for electrospraying is relatively low, the concentration of the chain entanglement of pectin molecules in solution is insufficient. After the silica contacts with water, the surface of the silica forms hydrated layer with hydroxyl groups, which is bonded to the pectin through hydrogen bonds. A silica molecule is connected with several pectin molecules, which increases the number of entanglement of pectin molecules, enhances the stability of “Tylor cone” during electrospraying process, and improves the encapsulating efficiency of polyphenols. Taking the pectin-silica composite as wall material, on one hand, nano-fillers cause the “tortuous path” and “permeability area reduction” effect of small molecules. On the other hand, the addition of silica increases the relative crystallinity of pectin, reduces the frequency of movement of the pectin molecular chain, reduces the penetration rate of water molecules and oxygen, improves the barrier property of pectin to water vapor and oxygen, reduces the contact probability of polyphenols with oxygen and water, and improves the stability of polyphenols. Compared with the water vapor transmission rate (6.174×10.sup.−11 g/m s Pa) and oxygen transmission rate (3.762×10.sup.−3 g/m.sup.2 s) of pectin electrospraying particles, the water vapor transmission rate of pectin silica polymer is reduced to below 3.0×10.sup.−11 g/m s Pa, and the oxygen transmission rate is reduced to 2.8×10.sup.−3 g/m.sup.2 s.

(15) (2) In this invention, the acidic aqueous solution is taken as the shell solution, the pectin-silica composite and the polyphenol solution are taken as the core solution, coaxial electrospraying is used to encapsulate the polyphenol, and the stability of polyphenols is improved.

(16) Specifically, when the acidic aqueous solution is used as the shell solution, its low viscosity favors Coulomb fission, and the entire droplet is uniformly and completely dried. In acidic environment, the pectin-silica composite solution loaded with polyphenols can be evaporated evenly. By slowing down the formation of semi-solid state on the surface of droplets, acidic aqueous solution helps polymer molecules to diffuse into droplets, thereby eliminating the potential collapse of particles, such that round particles with round surfaces and compact interiors are produced, and the distribution of polyphenols on the surface of droplets is reduced. On the other hand, for the acidic aqueous solution, the distribution state of the silica electrospraying particles is adjusted by adjusting the intensity of interaction between silica molecules and hydrogen bonds between silica and pectin. Synergistic effect of acidic aqueous solution and pectin-silica composite further improves the stability of polyphenols. After 50 days, the retention rate of polyphenols when the pectin-silica is taken as the carrier can reach more than 70% compared with the retention rate of 42.2% while polyphenol in the pectin electrospraying particles.

(17) The following experiments verify the effect.

Embodiment One

(18) (1) preparing a pectin solution: adding deionized water into pectin and stirring in a magnetic stirrer until the pectin is completely dissolved, and the pectin solution in an amount of 5% by weight being prepared;

(19) (2) preparing a silica suspension: adding the deionized water into a dry silica powder while stirring, and the silica suspension in an amount of 0.1% by weight being prepared;

(20) (3) preparing a pectin-silica composite: adding the above-mentioned silica suspension into the pectin solution drop by drop while stirring, and the pectin-silica composite being prepared;

(21) (4) adding 0.1 g tea polyphenols into the pectin-silica composite and stirring for 2 hours in the magnetic stirrer; and

(22) (5) placing the solution prepared in step (4) on an electrospraying device as a core solution, taking an acetic acid solution in an amount of 5% by weight as a shell solution, and electrospraying particles loaded polyphenol 1 being prepared; wherein electrospraying conditions include: electrostatic voltage: 16 kv; receiving distance: 13 cm; needle type of the core solution: inner diameter 0.6 mm, outer diameter 0.9 mm; needle type of the shell solution: inner diameter 0.12 mm, outer diameter 0.15 mm; room temperature: 20° C.; and air humidity: 45%.

Embodiment Two

(23) (1) preparing a pectin solution: adding deionized water into pectin and stirring in a magnetic stirrer until the pectin is completely dissolved, and the pectin solution in an amount of 10% by weight being prepared;

(24) (2) preparing a silica suspension: adding the deionized water into a dry silica powder while stirring, and the silica suspension in an amount of 0.5% by weight being prepared;

(25) (3) preparing a pectin-silica composite: adding the above-mentioned silica suspension into the pectin solution drop by drop while stirring, and the pectin-silica composite being prepared;

(26) (4) adding 0.5 g tea polyphenols into the pectin-silica composite and stirring for 2 hours in the magnetic stirrer; and

(27) (5) placing the solution prepared in step (4) on an electrospraying device as a core solution, taking an acetic acid solution in an amount of 10% by weight as a shell solution, and electrospraying particles loaded polyphenol 2 being prepared; wherein electrospraying conditions include: electrostatic voltage: 18 kv; receiving distance: 16 cm; needle type of the core solution: inner diameter 0.6 mm, outer diameter 0.9 mm; needle type of the shell solution: inner diameter 0.12 mm, outer diameter 0.15 mm; room temperature: 25° C.; and air humidity: 65%.

Embodiment Three

(28) (1) preparing a pectin solution: adding deionized water into pectin and stirring in a magnetic stirrer until the pectin is completely dissolved, and the pectin solution in an amount of 8% by weight being prepared;

(29) (2) preparing a silica suspension: adding the deionized water into a dry silica powder while stirring, and the silica suspension in an amount of 0.3% by weight being prepared;

(30) (3) preparing a pectin-silica composite: adding the above-mentioned silica suspension into the pectin solution drop by drop while stirring, and the pectin-silica composite being prepared;

(31) (4) adding 0.3 g tea polyphenols into the pectin-silica composite and stirring for 2 hours in the magnetic stirrer; and

(32) (5) placing the solution prepared in step (4) on an electrospraying device as a core solution, taking an acetic acid solution in an amount of 8% by weight as a shell solution, and electrospraying particles loaded polyphenol 3 being prepared;

(33) wherein electrospraying conditions include: electrostatic voltage: 18 kv; receiving distance: 15 cm; needle type of the core solution: inner diameter 0.6 mm, outer diameter 0.9 mm; needle type of the shell solution: inner diameter 0.12 mm, outer diameter 0.15 mm; room temperature: 25° C.; and air humidity: 65%.

Embodiment Four

(34) (1) preparing a pectin solution: adding deionized water into pectin and stirring in a magnetic stirrer until the pectin is completely dissolved, and the pectin solution in an amount of 10% by weight being prepared;

(35) (2) preparing a silica suspension: adding the deionized water into a dry silica powder while stirring, and the silica suspension in an amount of 0.5% by weight being prepared;

(36) (3) preparing a pectin-silica composite: adding the above-mentioned silica suspension into the pectin solution drop by drop while stirring, and the pectin-silica composite being prepared;

(37) (4) adding 0.5 g tea polyphenols into the pectin-silica composite and stirring for 2 hours in the magnetic stirrer; and

(38) (5) placing the solution prepared in step (4) on an electrospraying device as a core solution, and electrospraying particles loaded polyphenol 4 being prepared; wherein electrospraying conditions include: electrostatic voltage: 18 kv; receiving distance: 16 cm; needle type of the core solution: inner diameter 0.6 mm, outer diameter 0.9 mm; needle type of the shell solution: inner diameter 0.12 mm, outer diameter 0.15 mm; room temperature: 25° C.; and air humidity: 65%.

(39) Compared with Embodiment Two, Embodiment Four does not use the acidic aqueous solution as the shell solution for coaxial electrospraying.

(40) Samples 1-4 and pectin electrospraying particles are separately subjected to barrier property experiments and polyphenol retention rate experiments.

(41) Experiment of water vapor transmission rate: the electrospraying particles are made into a wafer with a diameter of 2.5 cm by using the tablet press machine and are sealed at the test cup. In the test cup, 3 g anhydrous CaCl.sub.2 is placed, and then the cup is placed in the environment with relative humidity (RH) of 90% and temperature of 40 C. The weight of the cup is tested every 1.5 h for 24 h. Then the water vapor transmission rate is calculated according to formula 1.

(42) $\mathrm{WVP}=\frac{\Delta m\times d}{A\times \Delta t\times \Delta P}$

(43) In the formula, WVP is the water vapor transmission rate (×10.sup.−11 g/m s Pa), Δm is the weight gain of the cup (g), d is the thickness of the electrospraying particle wafer (m), A is the area of the wafer (m2), Δt is the test time (s), and ΔP is the internal and external water vapor pressure difference (Pa) of the membrane

(44) Experiment of oxygen transmission rate: the electrospraying particles are made into a diameter of 2.5 cm by using the tablet press machine and are sealed at the test cup. 1 g iron powder, 2 g activated carbon, and 3 g NaCl are placed in the cup. and then the cup is placed in the environment with relative humidity (RH) of 75% and temperature of 25 C for 48 h. Then the oxygen transmission rate is calculated according to formula 2.

(45) $\mathrm{OP}=\frac{m-m_0}{A\times t}$

(46) In the formula, OP is the oxygen transmission rate (×10.sup.−3 g/m.sup.2 s), m is the mass of the cup after oxygen adsorption (g), m.sub.0 is the original mass of the cup (g), A is the area of the wafer (m.sup.2), and t is the test time (s).

(47) Experiment of polyphenol retention rate: 5 g electrospraying particles are placed in the environment with relative humidity (RH) of 90% and temperature of 30° C. The content of polyphenols in 1 g electrospraying particles is determined by high performance liquid chromatography every ten days. The first determination of polyphenol content is taken as the standard, which is recorded as 100% the retention rate of polyphenols, and then the retention rate of polyphenols in subsequent particles is calculated according to formula 3.

(48) $R\%=\frac{m}{m_0}\times 100\%$

(49) In the formula, m is the polyphenol content in electrospraying particles after storage, and m.sub.0 is the polyphenol content in the initial electrospraying particles.

(50) The experimental results are shown in Table 1.

(51) TABLE-US-00001 TABLE 1 Barrier properties of different samples water vapor oxygen transmission rate transmission rate (×10.sup.−11 g/m s Pa) (×10.sup.−3 g/m.sup.2 s) Pectin 6.174 3.762 electrospraying particles Sample 1 2.985 2.842 Sample 2 3.072 2.762 Sample 3 2.868 2.821 Sample 4 4.618 3.484

(52) As can be seen from the results in Table 1, the addition of silica increases the relative crystallinity of pectin, reduces the frequency of movement of the pectin molecular chain, reduces the penetration rate of water molecules and oxygen, improves the barrier property of pectin to water vapor and oxygen, reduces the contact probability of polyphenols with oxygen and water, and improves the stability of polyphenols.

(53) TABLE-US-00002 TABLE 2 Effects of different polymer carriers on the retention rate of polyphenols 10 d 20 d 30 d 40 d 50 d Pectin 100% 83.1% 62.5% 51.8% 42.2% electrospraying particles Sample 1 100% 92.6% 85.7% 79.7% 72.3% Sample 2 100% 96.4% 87.6% 80.6% 71.6% Sample 3 100% 94.3% 86.2% 80.1% 72.9% Sample 4 100% 81.2% 74.8% 65.4% 57.5%

(54) From the above table, it can be known that the acidic aqueous solution and pectin-silica composite have synergistic effect on the stability of polyphenol. After 50 days, the retention rate of polyphenols when the pectin-silica is taken as the carrier can reach more than 70% compared with the retention rate of 42.2% while polyphenol in the pectin electrospraying particles.

(55) In this invention, the pectin-silica composite is taken as the polyphenol loading carrier, the stability of polyphenols is improved by increasing the encapsulating efficiency of polyphenols and reducing the contact probability of polyphenols with oxygen and water. In acidic environment, the pectin-silica composite solution loaded with polyphenols can be evaporated evenly. By slowing down the formation of semi-solid state on the surface of droplets, acidic aqueous solution helps polymer molecules to diffuse into droplets, thereby eliminating the potential collapse of particles, such that round particles with round surfaces and compact interiors are produced, and the distribution of polyphenols on the surface of droplets is reduced. On the other hand, for the acidic aqueous solution, the distribution state of the silica electrospraying particles is adjusted by adjusting the intensity of interaction between silica molecules and hydrogen bonds between silica and pectin. Synergistic effect of acidic aqueous solution and pectin-silica composite further improves the stability of polyphenols.

(56) The basic principles, main features and advantages of this invention are shown and described above. Those skilled in the prior art should understand that the above-mentioned embodiments do not restrict the invention in any form, and any technical solutions obtained by equivalent substitution or equivalent transformation falls within the protection scope of this invention.