阅读说明：本技术 一种海藻酸钠基复合膜及其制备方法 (Sodium alginate-based composite membrane and preparation method thereof ) 是由 王利强 张晨宇 马淑凤 李江阔 宋会民 王国平 沈倩如 吴依琳 刘龙飞 于 2021-03-17 设计创作，主要内容包括：本发明公开一种海藻酸钠基复合膜及其制备方法,涉及食品包装技术领域。本发明公开的海藻酸钠基复合膜是以海藻酸钠和明胶为主要成膜材料,以水滑石和纳米氧化锌为助剂,以增塑剂、交联剂为辅料配制成溶液,再经流延成膜制得,其制备方法包括：首先将海藻酸钠加去离子水在水浴锅中搅拌糊化,然后加入明胶,与水滑石和纳米氧化米高度分散的混合液共混,再加入增塑剂和交联剂,最后定容,配制好的混合溶液再经流延成膜制得。本发明提供的海藻酸钠基复合膜无毒无污染,化学性质稳定,具有优良的机械性能和抗菌性,并具有具有良好的生物相容性、热稳定性和可降解性,可广泛应用于冷鲜肉等食品的内包装。(The invention discloses a sodium alginate-based composite membrane and a preparation method thereof, and relates to the technical field of food packaging. The sodium alginate-based composite membrane disclosed by the invention is prepared by preparing a solution by using sodium alginate and gelatin as main membrane forming materials, hydrotalcite and nano zinc oxide as auxiliary agents and plasticizer and cross-linking agent as auxiliary materials, and then performing casting membrane forming, wherein the preparation method comprises the following steps of: firstly, adding sodium alginate into deionized water, stirring and pasting in a water bath kettle, then adding gelatin, blending with a mixed solution of hydrotalcite and nano oxidized rice which are highly dispersed, then adding a plasticizer and a cross-linking agent, finally fixing the volume, and performing casting film forming on the prepared mixed solution to obtain the sodium alginate nano oxidized rice film. The sodium alginate-based composite membrane provided by the invention is nontoxic and pollution-free, has stable chemical properties, excellent mechanical properties and antibacterial properties, good biocompatibility, thermal stability and degradability, and can be widely applied to inner packaging of foods such as chilled meat.)

1. The sodium alginate-based composite film is characterized in that sodium alginate and gelatin are used as main film forming materials, hydrotalcite and nano zinc oxide are used as auxiliary agents, a plasticizer and a cross-linking agent are used as auxiliary materials to prepare a solution, and then the solution is subjected to casting film forming to obtain the sodium alginate-based composite film.

2. The sodium alginate-based composite membrane of claim 1, which is prepared from the following raw materials in parts by weight: 2-4 parts of sodium alginate, 0-2 parts of gelatin, 0.2-1.0 part of hydrotalcite, 0.4-1.2 parts of nano zinc oxide, 0.4-1.2 parts of plasticizer, 0.04-0.2 part of cross-linking agent and 200 parts of deionized water.

3. The sodium alginate-based composite membrane according to claim 2, wherein the sodium alginate is natural polysaccharide sodium alginate.

4. The sodium alginate-based composite membrane according to claim 2, wherein the hydrotalcite is magnesium aluminum hydrotalcite.

5. The sodium alginate-based composite membrane according to claim 2, wherein the plasticizer is glycerin.

6. The sodium alginate-based composite membrane of claim 2, wherein the cross-linking agent is calcium chloride.

7. A method for preparing the sodium alginate-based composite membrane as claimed in claim 1 or 2, which comprises the following steps:

(1) weighing raw materials according to the parts by weight of the raw materials of the sodium alginate-based composite membrane;

(2) gelatinizing sodium alginate: adding sodium alginate into 90-110 parts of deionized water, and carrying out water bath gelatinization for 15-25 min at 50-70 ℃ to prepare a gelatinization solution;

(3) adding gelatin into the gelatinized solution prepared in the step (2), and stirring for 15-25 min at the stirring speed of 350-450 r/min to prepare a mixed solution A;

(4) dissolving hydrotalcite and nano zinc oxide in 40-60 parts of deionized water, and highly dispersing the deionized water and the nano zinc oxide by using an ultrasonic cell dispersing agent to prepare a mixed solution B;

(5) mixing the mixed solution A and the mixed solution B, and uniformly mixing to obtain a mixed solution C;

(6) adding a plasticizer and a cross-linking agent into the mixed solution C prepared in the step (5), adding 30-70 parts of deionized water, fixing the volume to 200mL, stirring for 10-15 min at a stirring speed of 350-450 r/min to prepare a mixed solution D;

(7) casting and film forming: pouring 45-55 mL of mixed solution D onto a dry and clean organic glass plate with the same size and surface, casting to form a film, then placing the film in a vacuum drying oven at the temperature of 40-70 ℃ for drying for 3-6 h, cooling and uncovering the film to obtain the sodium alginate-based composite film.

8. The preparation method of the sodium alginate-based composite membrane according to claim 7, wherein the water bath temperature is always kept between 50 and 70 ℃ in the stirring and blending processes of the steps (3) to (6).

9. The preparation method of the sodium alginate-based composite membrane according to claim 7, wherein the stirring speed in the stirring process of the step (2), the step (3) and the step (6) is 350-450 r/min.

Technical Field

The invention belongs to the technical field of food packaging, and particularly relates to a sodium alginate-based composite membrane and a preparation method thereof.

Background

With the development of socioeconomic, the consumption concept of the public is changed, and the sanitation and safety of the goods are more focused on at present, especially on the aspect of food. Plastic packaging materials are widely used for food packaging and preservation due to their low cost and stable performance. However, plastic packaging is not easily degraded when being abandoned in the environment after use, and waste disposal is difficult, which is easy to cause white pollution. In addition, part of plastic food packages easily generate harmful substances and peculiar smell, so that the quality of the food is influenced, and the toxic and harmful substances are migrated into the food and have potential risks to the health of human bodies after being eaten. In recent years, with the enhancement of environmental awareness and the improvement of requirements on food quality, a novel non-toxic and harmless functional composite packaging material is adopted to replace plastic packaging, so that the environmental pollution degree is reduced to the minimum, the more excellent comprehensive performance is exerted, and the novel trend of food packaging development is developed.

The sodium alginate-based composite membrane is a membrane with a porous network structure, which is formed by taking natural polysaccharide sodium alginate as a main membrane forming substance, realizing blending with an inorganic functional material hydrotalcite and an inorganic antibacterial agent nano zinc oxide and realizing the interaction between different molecules. Although the sodium alginate pure film has good biodegradability and compatibility and lower cost, the pure film has poor mechanical property, crisp quality and insufficient strength and elasticity. In order to further make up for the defects of the pure film, the functional composite film is generated, and compared with the pure film, the composite film not only can make up for the defects in performance, but also can be mutually cooperated to achieve excellent performance which the pure film does not have. The tensile strength, the elongation at break, the water solubility, the water vapor transmission rate, the light transmittance and the like of the composite film are more outstanding, and the packaging requirement can be met.

Disclosure of Invention

The invention aims to provide a sodium alginate-based composite membrane and a preparation method thereof, wherein the composite membrane has the advantages of wide raw material source, low price, good thermal stability, excellent antibacterial property, high transparency, good mechanical property and barrier property, capability of being dissolved in water and complete biodegradation.

In order to realize the aim of the invention, the invention provides a sodium alginate-based composite membrane, which is prepared by preparing a solution by using sodium alginate and gelatin as main membrane forming materials, hydrotalcite and nano zinc oxide as auxiliary agents and a plasticizer and a cross-linking agent as auxiliary materials and then carrying out casting to form a membrane.

Further, the sodium alginate-based composite membrane comprises the following raw materials in parts by weight: 2-4 parts of sodium alginate, 0-2 parts of gelatin, 0.2-1.0 part of hydrotalcite, 0.4-1.2 parts of nano zinc oxide, 0.4-1.2 parts of plasticizer, 0.04-0.2 part of cross-linking agent and 200 parts of deionized water.

Further, the sodium alginate is natural polysaccharide sodium alginate.

Further, the hydrotalcite is magnesium aluminum hydrotalcite.

Further, the plasticizer is glycerol.

Further, the cross-linking agent is calcium chloride.

A preparation method of the sodium alginate-based composite membrane specifically comprises the following steps:

(1) weighing raw materials according to the parts by weight of the raw materials of the sodium alginate-based composite membrane;

(2) gelatinizing sodium alginate: adding sodium alginate into 90-110 parts of deionized water, and carrying out water bath gelatinization for 15-25 min at 50-70 ℃ to prepare a gelatinization solution;

(3) adding gelatin into the gelatinized solution prepared in the step (2), and stirring for 15-25 min at the stirring speed of 350-450 r/min to prepare a mixed solution A;

(4) dissolving hydrotalcite and nano zinc oxide in 40-60 parts of deionized water, and highly dispersing the deionized water and the nano zinc oxide by using an ultrasonic cell dispersing agent to prepare a mixed solution B;

(5) mixing the mixed solution A and the mixed solution B, and uniformly mixing to obtain a mixed solution C;

(6) adding a plasticizer and a cross-linking agent into the mixed solution C prepared in the step (5), adding 30-70 parts of deionized water, fixing the volume to 200mL, stirring for 10-15 min at a stirring speed of 350-450 r/min to prepare a mixed solution D;

(7) casting and film forming: pouring 45-55 mL of mixed solution D onto a dry and clean organic glass plate with the same size and surface, casting to form a film, then placing the film in a vacuum drying oven at the temperature of 40-70 ℃ for drying for 3-6 h, cooling and uncovering the film to obtain the sodium alginate-based composite film.

Further, the water bath temperature in the stirring and blending processes of the steps (3) to (6) is always kept between 50 and 70 ℃.

Further, the stirring speed in the stirring processes of the step (2), the step (3) and the step (6) is 350-450 r/min.

The invention achieves the following beneficial effects:

1. the sodium alginate-based composite film prepared by the invention is a colorless transparent film in appearance, the light transmittance is 72.51-88.73%, the tensile strength is 5.16-23.72 MPa, the elongation at break is 9.68-47.82%, the water vapor transmittance is 1.35-2.72 g/mm/(m 2 d/kPa), and the water solubility is 20.48-51.53%.

2. According to the invention, by adding the inorganic functional material hydrotalcite and the inorganic antibacterial agent nano zinc oxide, the mechanical property of the sodium alginate-based functional composite membrane is improved, and simultaneously, the barrier property of the composite membrane is also improved, so that the surface of the composite membrane is smooth and uniform and has no holes and cracks.

3. The main raw materials and the auxiliary agent for preparing the sodium alginate-based composite membrane are nontoxic, harmless and degradable materials, wherein the sodium alginate has wide sources and low price, and the hydrotalcite and the nano zinc oxide are inorganic materials and are substances harmless to the environment and human bodies, so that the prepared composite membrane is an environment-friendly material.

4. The sodium alginate-based composite membrane prepared by the invention has high transparency, luster, beautiful appearance, good mechanical property and barrier property, and can be made into films with different thicknesses and mechanical properties according to the needs. The sodium alginate-based composite film has excellent antibacterial property, can be applied to food inner packaging, is suitable for packaging fruits, milk, chilled meat, aquatic products and other food, and can effectively prolong the shelf life of the food.

5. The sodium alginate-based composite membrane prepared by the invention can be dissolved in water, can be completely biodegraded in the environment, and cannot cause any pollution to the environment.

6. The production method of the invention is safe, simple in process flow, low in production cost, capable of being widely popularized in the market and good in market prospect.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the preparation process, an electric stirrer is adopted for operation during stirring, and the electric stirrer adopts a JB-200-S digital display rotating speed electric stirrer manufactured by Shanghai specimen model factory; the stirring reaction is carried out in a water bath kettle, and the water bath kettle is controlled by adopting a YJ501 super constant-temperature water bath kettle manufactured by Ronghua instruments manufacturing Limited company of Jintan City in Jiangsu province.

The mechanical property of the invention is measured by adopting an LRX Plus type universal electronic material testing machine manufactured by LLOYD company in UK; the transmittance was measured by using a UV-2802 type UV-visible spectrophotometer manufactured by Uygur instruments Inc.

The sodium alginate-based composite membrane of the present invention will be further described with reference to the following specific examples.

Example 1

The sodium alginate-based composite membrane comprises the following raw materials: 3g of sodium alginate, 1g of gelatin, 0.4g of hydrotalcite, 1g of nano zinc oxide, 1g of glycerol, 0.08g of calcium chloride and 200mL of deionized water.

The preparation method of the sodium alginate-based composite membrane comprises the following steps: adding 3g of sodium alginate into 100mL of deionized water, setting the stirring speed to be 350-450 r/min, carrying out water bath gelatinization for 20min at 60 ℃ to obtain a gelatinization solution, adding 1g of gelatin, and stirring for 20min to obtain a mixed solution A; weighing 0.4g of hydrotalcite and 1g of nano zinc oxide, dissolving in 50mL of deionized water, and highly dispersing by using an ultrasonic cell dispersion machine to prepare a mixed solution B; mixing the mixed solution A and the mixed solution B to prepare a mixed solution C; weighing 1g of glycerol and 0.08g of calcium chloride, adding the glycerol and the calcium chloride into the mixed solution C, stirring the mixture for 20min in a water bath at the temperature of 60 ℃, wherein the stirring speed is 350-450 r/min, fixing the volume to 200ml by using deionized water, and stirring the mixture for 10min in the water bath to obtain mixed solution D; and (3) casting the mixed solution D on an organic glass plate to form a film, setting the temperature of a drying oven to be 50 ℃, drying for 3-6 h, cooling, and then uncovering the film to obtain the sodium alginate-based composite film.

The casting film forming method of the embodiment is as follows: pouring 45-55 mL of the mixed solution D onto a dry and clean organic glass plate with the same size and surface, and performing tape casting to form a film.

According to detection, the performance of the sodium alginate-based composite membrane in the embodiment is as follows: 22.61MPa of tensile strength, 37.85 percent of breaking elongation, 1.98 g/mm/(m 2 d/kPa) of water vapor transmission rate, 32.92 percent of water solubility and 84.51 percent of light transmittance.

Example 2

The sodium alginate-based composite membrane comprises the following raw materials: 2.5g of sodium alginate, 1.5g of gelatin, 0.4g of hydrotalcite, 0.8g of nano zinc oxide, 1g of glycerol, 0.08g of calcium chloride and 200mL of deionized water.

The preparation method of the sodium alginate-based composite membrane comprises the following steps: adding 2.5g of sodium alginate into 100mL of deionized water, gelatinizing in a water bath at 60 ℃ for 20min, adding 1.5g of gelatin, and stirring for 20 min; weighing 0.4g of hydrotalcite and 0.8g of nano zinc oxide, dissolving in 50mL of deionized water, and highly dispersing by using an ultrasonic cell dispersion machine; blending the two obtained solutions; weighing 1g of glycerol and 0.08g of calcium chloride, adding the glycerol and the calcium chloride into the blended solution, stirring in a water bath for 20min, fixing the volume to 200ml with deionized water, stirring in a water bath for 10min, casting a film on an organic glass plate, setting the temperature of a drying box to be 50 ℃, drying, cooling and uncovering the film to obtain the sodium alginate-based composite film.

According to detection, the performance of the sodium alginate-based composite membrane in the embodiment is as follows: the tensile strength is 19.71MPa, the elongation at break is 32.83 percent, the water vapor transmission rate is 1.71 g.mm/(m 2 d.kPa), the water solubility is 28.64 percent, and the light transmittance is 85.79 percent.

Example 3

The sodium alginate-based composite membrane comprises the following raw materials: 3.5g of sodium alginate, 0.5g of gelatin, 0.6g of hydrotalcite, 1g of nano zinc oxide, 1g of glycerol and 0.08g of calcium chloride.

The preparation method of the sodium alginate-based composite membrane comprises the following steps: adding 3.5g of sodium alginate into 100mL of deionized water, gelatinizing in a water bath at 60 ℃ for 20min, adding 0.5g of gelatin, and stirring for 20 min; weighing 0.6g of hydrotalcite and 1g of nano zinc oxide, dissolving in 50mL of deionized water, and highly dispersing by using an ultrasonic cell dispersion machine; blending the two obtained solutions; weighing 1g of glycerol and 0.08g of calcium chloride, adding the glycerol and the calcium chloride into the blending solution, stirring in a water bath for 20min, fixing the volume to 200ml by using deionized water, stirring in a water bath for 10min, casting a film on an organic glass plate, setting the temperature of a drying box to be 50 ℃, drying, cooling and uncovering the film to obtain the sodium alginate-based composite film.

Through detection, the performance of the sodium alginate-based composite membrane of the embodiment is as follows: 17.33MPa of tensile strength, 26.59 percent of breaking elongation, 1.75 g.mm/(m 2 d.kPa) of water vapor transmission rate, 33.29 percent of water solubility and 85.01 percent of light transmittance.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.