阅读说明：本技术 一种木聚糖基复合保鲜膜及其制备方法 (Xylan-based composite preservative film and preparation method thereof ) 是由 苗庆显 刘庚玫 张琛 陈梦颖 陈礼辉 倪永浩 于 2021-09-14 设计创作，主要内容包括：本发明涉及一种食品保鲜膜,尤其涉及一种木聚糖基复合保鲜膜及其制备方法。本发明利用茶多酚与木聚糖、聚乙烯醇和山梨醇进行复配,获得木聚糖/聚乙烯醇/山梨醇/茶多酚复合保鲜膜母液,然后成膜制备水溶性木聚糖基复合保鲜膜。本发明利用茶多酚与木聚糖、聚乙烯醇和山梨醇进行复配,所用成膜材料全部为水溶性组分,可解决当前食品保鲜膜水溶性差、制备工艺复杂、成本高、应用不方便等问题。制备的木聚糖/聚乙烯醇/山梨醇/茶多酚复合膜具有无毒、水溶性好、制备工艺简单、成本低、应用简便以及具有良好保鲜和抑菌性能的优点。(The invention relates to a food preservative film, in particular to a xylan-based composite preservative film and a preparation method thereof. The invention utilizes tea polyphenol to be compounded with xylan, polyvinyl alcohol and sorbitol to obtain xylan/polyvinyl alcohol/sorbitol/tea polyphenol composite preservative film mother liquor, and then the water-soluble xylan-based composite preservative film is prepared by film forming. According to the invention, tea polyphenol, xylan, polyvinyl alcohol and sorbitol are compounded, and all film-forming materials are water-soluble components, so that the problems of poor water solubility, complex preparation process, high cost, inconvenience in application and the like of the current food preservative film can be solved. The prepared xylan/polyvinyl alcohol/sorbitol/tea polyphenol composite membrane has the advantages of no toxicity, good water solubility, simple preparation process, low cost, simple and convenient application and good fresh-keeping and antibacterial properties.)

1. A preparation method of a xylan-based composite preservative film is characterized by comprising the following steps: compounding tea polyphenol with xylan, polyvinyl alcohol and sorbitol to obtain xylan/polyvinyl alcohol/sorbitol/tea polyphenol composite preservative film mother liquor, and then forming a film to prepare the xylan-based composite preservative film.

2. The preparation method of the xylan-based composite preservative film according to claim 1, wherein: the method comprises the following steps:

step 1, preparing a mixed solution of polyvinyl alcohol, xylan and sorbitol: respectively stirring and dissolving polyvinyl alcohol, xylan and sorbitol in hot water, and then mixing and stirring the three solutions uniformly;

step 2, preparing a tea polyphenol solution: dissolving tea polyphenol in water to obtain tea polyphenol solution;

step 3, preparing a composite preservative film mother solution: mixing the tea polyphenol solution obtained in the step 2 with the mixed solution obtained in the step 1, and uniformly stirring to obtain a xylan/polyvinyl alcohol/sorbitol/tea polyphenol composite preservative film mother liquor;

and 4, step 4: and (3) coating the composite preservative film mother liquor obtained in the step (3) on the surfaces of fruits and vegetables, or pouring the composite preservative film mother liquor into a polytetrafluoroethylene surface dish, and naturally drying the composite preservative film mother liquor at room temperature to obtain the xylan-based composite preservative film.

3. The preparation method of the xylan-based composite preservative film according to claim 2, wherein: the alcoholysis degree of the polyvinyl alcohol adopted in the step 1 is 87% -89%.

4. The preparation method of the xylan-based composite preservative film according to claim 2, wherein: the molecular weight of the xylan in the step 1 is 500-25000 g/moL.

5. The preparation method of the xylan-based composite preservative film according to claim 2, wherein: the water adopted in the step 1 and the step 2 is deionized water.

6. The preparation method of the xylan-based composite preservative film according to claim 2, wherein: and 2, putting the tea polyphenol into deionized water, and stirring and dissolving the tea polyphenol in a constant-temperature water bath kettle at the temperature of 60 ℃.

7. The preparation method of the xylan-based composite preservative film according to claim 1, wherein: the amount of each component in the composite preservative film mother liquor in the step 3 is 40-60 parts of xylan, 30-50 parts of polyvinyl alcohol, 5-9 parts of sorbitol and 1-5 parts of tea polyphenol according to the mass parts.

8. The xylan-based composite wrap manufactured by the method according to any one of claims 1 to 7.

Technical Field

The invention relates to a food preservative film, in particular to a xylan-based composite preservative film and a preparation method thereof.

Background

Along with the improvement of living standard of people, the requirement on the freshness of food is also improved, and particularly, effective protection measures must be taken to ensure the freshness of vegetables and fruits for the foods which are easy to rot and deteriorate at normal temperature.

At present, plastic films which are difficult to degrade and are made of organic polymer materials are mostly used as preservative films in daily life, and can cause secondary pollution to food and environment. In order to solve the problems, biodegradable preservative films are also researched and prepared in the follow-up process, for example, polylactic acid, sodium alginate, collagen, starch, cellulose and the like are used as film forming materials, and chitosan, plant polyphenol and other antibacterial materials are added. Hemicellulose is one of three major components of plant resources, is a natural carbohydrate, is abundant in nature, and is not fully utilized at present. Compared with cellulose, polylactic acid, starch and other materials, the hemicellulose (broad-leaved wood and crop straw residues and bamboo wood are mainly xylan according to different raw materials, and the softwood is mainly polymannan) has the advantages of high molecular chain branching degree and low molecular weight, and is good in water solubility and processability. After the preservative film mother solution taking hemicellulose as a base material is coated on the surfaces of fruits and vegetables, the preservative film mother solution can be used after being washed by water when being eaten, and the hemicellulose can be naturally biodegraded after being dissolved in water, so that the preservative film mother solution does not bring harm to human bodies, and avoids secondary pollution to the environment.

In order to improve the strength and the barrier property of the xylan film, polyvinyl alcohol with good film forming property, chemical stability and barrier property can be added to prepare the xylan composite film. Generally, the degree of alcoholysis of polyvinyl alcohol has a greater effect on its solubility than the degree of polymerization. At present, most of composite preservative films with preservation and antibacterial properties take chitosan as an antibacterial agent, and research on the preparation of the composite preservative films by mixing plant polyphenol and chitosan has achieved a certain preservation effect.

Disclosure of Invention

The invention aims to solve the problems that the existing food preservative film is poor in water solubility, complex in preparation process, high in cost, inconvenient to apply and the like.

The invention is realized by the following steps:

the invention firstly provides a preparation method of a xylan-based composite preservative film, which comprises the steps of compounding tea polyphenol with xylan, polyvinyl alcohol and sorbitol to obtain xylan/polyvinyl alcohol/sorbitol/tea polyphenol composite preservative film mother liquor, and then forming a film to prepare the xylan-based composite preservative film.

Further, the method comprises the steps of:

step 1, dissolving polyvinyl alcohol, xylan and sorbitol: respectively stirring and dissolving polyvinyl alcohol, xylan and sorbitol in hot water, and then mixing and stirring the three solutions uniformly;

step 2, dissolving tea polyphenol: dissolving tea polyphenol in water to obtain tea polyphenol solution;

step 3, preparing a composite preservative film mother solution: mixing the tea polyphenol solution obtained in the step 2 with the mixed solution obtained in the step 1, and uniformly stirring to obtain a xylan/polyvinyl alcohol/sorbitol/tea polyphenol composite preservative film mother liquor;

and 4, step 4: and (3) coating the composite preservative film mother liquor obtained in the step (3) on the surfaces of fruits and vegetables, or pouring the composite preservative film mother liquor into a polytetrafluoroethylene surface dish, and naturally drying the composite preservative film mother liquor at room temperature to obtain the xylan-based composite preservative film.

Further, the alcoholysis degree of the polyvinyl alcohol adopted in the step 1 is 87% -89%.

Further, the molecular weight of xylan in step 1 is 500-10000 g/moL.

Further, the water used in step 1 and step 2 is deionized water.

Further, the tea polyphenol obtained in the step 2 is put into deionized water and is stirred and dissolved in a constant-temperature water bath kettle at the temperature of 60 ℃.

Furthermore, the composite preservative film mother liquor in the step 3 comprises 40-60 parts of xylan, 30-50 parts of polyvinyl alcohol, 5-9 parts of sorbitol and 1-5 parts of tea polyphenol according to mass parts.

The invention also provides the xylan-based composite preservative film prepared by the preparation method.

The invention has the following advantages:

the xylan/polyvinyl alcohol/sorbitol/tea polyphenol composite preservative film prepared by the invention has the advantages of water solubility, no toxicity, natural degradation, no toxicity, good water solubility, simple preparation process, good biodegradability, low cost, simple and convenient application, and good preservation and antibacterial performance. The composite preservative film prepared by the invention can be directly used for preserving various fruits and vegetables, can be washed off in water, has no residue on the fruits and vegetables, has the antibacterial and preservative effects, and is a functional composite film with excellent performance.

Drawings

The invention will be further described with reference to the following examples with reference to the accompanying drawings.

FIG. 1 is a graph showing the preservation effect of the composite preservative film prepared in example 1 of the present invention before and after coating on cherry tomatoes for 15 days; wherein the left image is after coating and the right image is before coating.

FIG. 2 is a diagram showing the preservation effect of the composite preservative film prepared in example 1 of the present invention on cherry tomatoes coated with different preservative film mother solutions; wherein the left picture is coated with a fresh-keeping composite membrane mother liquor containing xylan/polyvinyl alcohol/tea polyphenol, and the right picture is coated with a fresh-keeping composite membrane mother liquor containing xylan/polyvinyl alcohol/tea polyphenol/sorbitol.

FIG. 3 is a diagram of the bacteriostatic effect of the composite preservative film prepared in example 1 of the present invention in a bacteriostatic test on Escherichia coli by a punching method; wherein the left graph is after coating the fresh-keeping composite membrane mother liquor, and the right graph is before coating the fresh-keeping composite membrane mother liquor.

FIG. 4 is a diagram of the bacteriostatic effect of the composite preservative film prepared in example 1 of the present invention in a bacteriostatic test on Escherichia coli by a punching method; wherein the left picture is coated with a fresh-keeping composite membrane mother liquor containing xylan/polyvinyl alcohol/tea polyphenol, and the right picture is coated with a fresh-keeping composite membrane mother liquor containing xylan/polyvinyl alcohol/tea polyphenol/sorbitol.

FIG. 5 is a graph showing the effect of solubility of the composite wrap prepared in example 1 of the present invention; wherein the left picture is a fresh-keeping composite film coated with xylan/polyvinyl alcohol/tea polyphenol, and the right picture is a fresh-keeping composite film coated with xylan/polyvinyl alcohol/tea polyphenol/sorbitol.

Detailed Description

The invention firstly provides a preparation method of a xylan-based composite preservative film, which takes xylan as a substrate, polyvinyl alcohol as a reinforcing material, sorbitol as a plasticizer and tea polyphenol as a main antibacterial substance to prepare the xylan-based composite preservative film.

Further, the method comprises the steps of:

step 1, dissolving polyvinyl alcohol, xylan and sorbitol: respectively stirring and dissolving polyvinyl alcohol, xylan and sorbitol in hot water, and then mixing and stirring the three solutions uniformly;

step 2, dissolving tea polyphenol: dissolving tea polyphenol in water to obtain tea polyphenol solution;

step 3, preparing a composite preservative film mother solution: mixing the tea polyphenol solution obtained in the step 2 with the mixed solution obtained in the step 1, and uniformly stirring to obtain a xylan/polyvinyl alcohol/sorbitol/tea polyphenol composite preservative film mother liquor;

and 4, step 4: and (3) coating the composite preservative film mother liquor obtained in the step (3) on the surfaces of fruits and vegetables, or pouring the composite preservative film mother liquor into a polytetrafluoroethylene surface dish, and naturally drying the composite preservative film mother liquor at room temperature to obtain the xylan-based composite preservative film.

Further, the alcoholysis degree of the polyvinyl alcohol adopted in the step 1 is 87% -89%.

Further, the molecular weight of xylan in step 1 is 500-10000 g/moL.

Further, the water used in step 1 and step 2 is deionized water.

Further, the tea polyphenol obtained in the step 2 is put into deionized water and is stirred and dissolved in a constant-temperature water bath kettle at the temperature of 60 ℃.

Furthermore, the composite preservative film mother liquor in the step 3 comprises 40-60 parts of xylan, 30-50 parts of polyvinyl alcohol, 5-9 parts of sorbitol and 1-5 parts of tea polyphenol according to mass parts.

Referring to fig. 1-5, the technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings and the detailed description. 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. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1:

respectively weighing xylan, polyvinyl alcohol and sorbitol according to certain mass, placing the xylan, the polyvinyl alcohol and the sorbitol into three glass beakers filled with 100 ml of deionized water, stirring and dissolving the xylan, the polyvinyl alcohol and the sorbitol for 1 hour in a constant-temperature water bath at 80 ℃, then placing a certain volume of each of the three solutions into one glass beaker, and stirring and mixing the solutions uniformly. Weighing a certain mass of tea polyphenol, placing the tea polyphenol into a glass beaker filled with 100 ml of deionized water, and stirring and dissolving the tea polyphenol for 1 hour in a constant-temperature water bath at 60 ℃. And finally, mixing a certain volume of tea polyphenol water solution with the xylan/polyvinyl alcohol/sorbitol mixed solution, and stirring and mixing uniformly. In the obtained xylan/polyvinyl alcohol/sorbitol/tea polyphenol mixed solution, the mass parts of xylan, polyvinyl alcohol, sorbitol and tea polyphenol are 50 parts, 40 parts, 7 parts and 3 parts respectively. Soaking cherry tomatoes in the composite preservative film mother liquor for 5 seconds, taking out, air-drying at room temperature, and standing for 15 days to detect that the indexes of the cherry tomatoes are that the weight loss rate is 3.36%, the hardness is reduced by 15%, the content of soluble solids is reduced by 0.2%, the content of vitamin C is reduced by 10%, and the indexes are lower than the detection data of the composite preservative film mother liquor which is not coated. Compared with the xylan/polyvinyl alcohol/tea polyphenol composite film only added with tea polyphenol, the weight loss rate is reduced by 0.13 percent, the hardness is improved by 0.22 percent, the content of soluble solid is improved by 0.5 percent, the content of vitamin C is improved by 3.0 percent, and the fresh-keeping effect is obviously improved after sorbitol is further added.

As shown in fig. 1, the cherry tomatoes coated with the composite preservative film mother solution had a more rounded surface and substantially no shrinkage, compared to the cherry tomatoes not coated with the composite preservative film mother solution. As shown in fig. 2, the surface of the cherry tomatoes was more rounded and slightly shrunk after the additional addition of sorbitol, compared to the cherry tomatoes coated with only the composite preservative film mother solution containing xylan/polyvinyl alcohol/tea polyphenol.

As shown in figures 3 and 4, bacteriostatic experiments on escherichia coli show that compared with a sample which is not coated with the preservative film mother liquor, the bacteriostatic circle is obviously increased after the preservative film mother liquor is coated, and the bacteriostatic effect is obvious. Compared with the xylan/polyvinyl alcohol/tea polyphenol composite membrane only added with tea polyphenol, the antibacterial zone is further increased after sorbitol is added, and the antibacterial effect is further enhanced.

As shown in fig. 5, the solubility of the two composite preservative films of xylan/polyvinyl alcohol/tea polyphenol and xylan/polyvinyl alcohol/tea polyphenol/sorbitol in deionized water was very good, and after soaking in water for 5 minutes, both composite films were found to be substantially completely dissolved.

Moreover, after sorbitol is added, the strength performance of the xylan composite membrane is improved, the tensile strength is improved by 1.1MPa, and the elongation at break is improved by 5%.

In conclusion, the composite preservative film obtained by the invention has obvious preservation and bacteriostasis effects and better water solubility. The composition of the sorbitol and the tea polyphenol has obvious synergistic effect, and the fresh-keeping and bacteriostatic effects and the strength performance of the film are further improved compared with the strength performance of the film prepared by singly adopting the tea polyphenol.

Example 2:

respectively weighing xylan, polyvinyl alcohol and sorbitol according to certain mass, placing the xylan, the polyvinyl alcohol and the sorbitol into three glass beakers filled with 100 ml of deionized water, stirring and dissolving the xylan, the polyvinyl alcohol and the sorbitol for 1 hour in a constant-temperature water bath at 80 ℃, then placing a certain volume of each of the three solutions into one glass beaker, and stirring and mixing the solutions uniformly. Weighing a certain mass of tea polyphenol, placing the tea polyphenol into a glass beaker filled with 100 ml of deionized water, and stirring and dissolving the tea polyphenol for 1 hour in a constant-temperature water bath at 60 ℃. And finally, mixing a certain volume of tea polyphenol water solution with the xylan/polyvinyl alcohol/sorbitol mixed solution, and stirring and mixing uniformly. In the obtained xylan/polyvinyl alcohol/sorbitol/tea polyphenol mixed solution, the mass parts of xylan, polyvinyl alcohol, sorbitol and tea polyphenol are 55 parts, 35 parts, 5 parts and 5 parts respectively. Soaking cherry tomatoes in the composite preservative film mother solution for 5 seconds, taking out, air-drying at room temperature, and standing for 15 days to detect that the cherry tomatoes have the indexes that the weight loss rate is 2.82%, the hardness is reduced by 9%, the content of soluble solids is reduced by 0.1%, and the content of vitamin C is reduced by 6%. Antibacterial experiments on staphylococcus aureus and escherichia coli show that the antibacterial zone is obviously increased, and the antibacterial effect is obvious.

Although specific embodiments of the invention have been described above, it will be understood by those skilled in the art that the specific embodiments described are illustrative only and are not limiting upon the scope of the invention, and that equivalent modifications and variations can be made by those skilled in the art without departing from the spirit of the invention, which is to be limited only by the appended claims.