阅读说明：本技术 壳聚糖/曲酸/氯代曲酸复合抑菌保鲜膜及其制备方法 (Chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film and preparation method thereof ) 是由 刘晓丽 夏文水 于沛沛 姜启兴 许艳顺 于 2019-11-05 设计创作，主要内容包括：本发明公开了一种壳聚糖/曲酸/氯代曲酸复合抑菌保鲜膜,所述复合抑菌保鲜膜至少包括层叠设置的第一复合膜和第二复合膜；其中,所述第一复合膜为壳聚糖与曲酸复合膜,且壳聚糖的数均分子量为150～300KDa,脱乙酰度≥90％；所述第二复合膜为壳聚糖与氯代曲酸复合膜,且壳聚糖的数均分子量为400～800KDa,脱乙酰度≥85％。本发明还公开了所述复合抑菌保鲜膜的制备方法。本发明的壳聚糖/曲酸/氯代曲酸复合抑菌保鲜膜,具有良好的成膜性和机械性能,有较低的水蒸气透过系数和良好的抑菌活性,可避免食品水分的大量流失和达到较好的保鲜效果。(The invention discloses a chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film which at least comprises a first composite film and a second composite film which are arranged in a laminated manner; the first composite membrane is a chitosan and kojic acid composite membrane, the number average molecular weight of chitosan is 150-300 KDa, and the deacetylation degree is larger than or equal to 90%; the second composite membrane is a chitosan and chlorinated kojic acid composite membrane, the number average molecular weight of chitosan is 400-800 KDa, and the deacetylation degree is more than or equal to 85%. The invention also discloses a preparation method of the composite antibacterial preservative film. The chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film disclosed by the invention has good film-forming property and mechanical property, has a lower water vapor transmission coefficient and good bacteriostatic activity, can avoid a large amount of loss of food water and can achieve a good preservative effect.)

1. A chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film is characterized by at least comprising a first composite film and a second composite film which are arranged in a stacked mode;

the first composite membrane is a chitosan and kojic acid composite membrane, the number average molecular weight of chitosan is 150-300 KDa, and the deacetylation degree is larger than or equal to 90%; the second composite membrane is a chitosan and chlorinated kojic acid composite membrane, the number average molecular weight of chitosan is 400-800 KDa, and the deacetylation degree is more than or equal to 85%.

2. The chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film according to claim 1, wherein in the first composite film, the mass ratio of kojic acid to chitosan is 0.05-0.15: 0.5-1.2; in the second composite film, the mass ratio of the chlorinated kojic acid to the chitosan is 0.05-0.15: 0.5-1.2.

3. The chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film according to claim 1, wherein the first composite film and/or the second composite film further comprises a plasticizer, and the mass ratio of the plasticizer to the chitosan is 0.5-0.8: 0.5-1.2.

4. The chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film according to claim 3, wherein the plasticizer is at least one selected from glycerol, sorbitol, polyethylene glycol and stearic acid.

5. The chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film according to claim 1, wherein the thickness of the first composite film is 35.55-39.85 μm, and the thickness of the second composite film is 36.68-41.06 μm.

6. The chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film according to claim 1, wherein the first composite film and/or the second composite film is a cast film.

7. A preparation method of a chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film is characterized by comprising the following steps:

preparing a chitosan/kojic acid mixed membrane solution and a chitosan/chlorinated kojic acid mixed membrane solution; wherein, in the chitosan/kojic acid mixed membrane liquid, the number average molecular weight of chitosan is 150-300 KDa, and the deacetylation degree is more than or equal to 90%; in the chitosan/chlorinated kojic acid mixed membrane liquid, the number average molecular weight of chitosan is 400-800 KDa, and the degree of deacetylation is more than or equal to 85%;

casting the chitosan/kojic acid mixed membrane solution into a membrane, and drying; and then casting the chitosan/chlorinated kojic acid mixed film liquid on the surface of the chitosan/chlorinated kojic acid mixed film liquid to form a film, and drying to obtain the chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film.

8. The preparation method of the chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film according to claim 7, wherein the preparation method of the chitosan/kojic acid mixed film liquid comprises the following steps:

dissolving chitosan in 1% acetic acid solution, stirring and performing ultrasonic treatment until the chitosan is completely dissolved to obtain 5-12 g/L chitosan solution; adding a plasticizer into the chitosan solution according to the ratio of 0.5-0.8: 0.5-1.2 of the plasticizer to be uniformly stirred for later use;

adding kojic acid into the solution according to the ratio of 0.05-0.15: 0.5-1.2 of kojic acid to chitosan, and stirring for 30-60 min at the stirring speed of 400-800 r/min; carrying out ultrasonic dispersion for 5-10 min, wherein the frequency is 35-50 KHz; and standing for 1-2 h, and carrying out vacuum pressure reduction and defoaming for 10-20 min to obtain the chitosan/kojic acid mixed membrane solution.

9. The preparation method of the chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film according to claim 7, wherein the preparation method of the chitosan/chlorinated kojic acid mixed film liquid comprises the following steps:

dissolving chitosan in 1% acetic acid solution, stirring and performing ultrasonic treatment until the chitosan is completely dissolved to obtain 5-12 g/L chitosan solution; adding a plasticizer into the chitosan solution according to the ratio of 0.5-0.8: 0.5-1.2 of the plasticizer to be uniformly stirred for later use;

adding the chlorinated kojic acid into the solution according to the proportion of 0.05-0.15: 0.5-1.2 of the chlorinated kojic acid and chitosan, and stirring for 45-90 min at the stirring speed of 800-1000 r/min; carrying out ultrasonic dispersion for 10-15 min, wherein the frequency is 35-50 KHz; and standing for 1-2 h, and carrying out vacuum pressure reduction and defoaming for 15-25 min to obtain the chitosan/chlorinated kojic acid mixed membrane solution.

10. The preparation method of the chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film according to claim 7, wherein the drying conditions of the chitosan/kojic acid composite film liquid are as follows: the drying temperature is 35-55 ℃, and the drying time is 1-2 h; the drying conditions of the chitosan/chlorinated kojic acid composite membrane liquid are as follows: the drying temperature is 55-75 ℃, and the drying time is 2-4 h.

Technical Field

The invention relates to the technical field of food packaging materials, in particular to a chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film and a preparation method thereof.

Background

The plastic wrap is commonly used for keeping food fresh in daily life, the most commonly used plastic wrap is polyethylene wrap at present, but the plastic wrap is difficult to degrade, so that the problem of serious plastic waste pollution is brought, and harmful substances to human bodies and the like can be decomposed after heating. When food is frozen and preserved, the preservative film can be frozen and stuck on the food and cannot be removed, the situation of mistaken eating can be avoided slightly, and the health of eaters is seriously damaged. Therefore, other environment-friendly, safe and harmless materials are urgently needed to replace harmful preservative film materials.

Natural polysaccharides have attracted extensive attention from researchers because of their abundant sources, biodegradability, biocompatibility, safety, and non-toxicity. Chitosan is a natural alkaline polysaccharide, has good biocompatibility and biodegradability, and degradation products generally have no toxic or side effect on human bodies, do not accumulate in the bodies, have no immunogenicity, and are widely selected as preservative film materials. The chitosan also has a certain bacteriostatic action and has obvious inhibitory action on bacteria, mould, fungi and microzyme. In addition, the chitosan has good film forming property, chitosan molecules can be crosslinked into hydrogen bonds in a proper solvent, and the film forming property is good, so that the chitosan is considered as an ideal material for developing a novel natural antibacterial preservative film.

Kojic acid is a common weakly acidic metabolite produced by aerobic fermentation of microorganisms such as Aspergillus (Aspergillus) and Acetobacter (Acetobacter). The kojic acid has the special structure similar to that of catechol, so that the kojic acid has the functions of resisting bacteria, resisting virus, resisting inflammation, resisting tumor, resisting oxidation, etc. and is safe and non-toxic. The chloro kojic acid is a product with stronger bacteriostatic activity obtained by derivatization of a multifunctional skeleton of kojic acid, is a good ligand for nucleophilic substitution and electrophilic substitution reaction, and has stronger antibacterial and antifungal effects because of being capable of chelating metal cations necessary for the metabolism of bacterial cells.

Disclosure of Invention

The invention aims to solve the technical problem of providing a chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film and a preparation method thereof, and overcomes the defects that the chitosan film has poor water vapor barrier property and mechanical strength in the prior art.

In order to solve the technical problems, the invention provides a chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film, which at least comprises a first composite film and a second composite film which are arranged in a laminated manner;

the first composite membrane is a chitosan and kojic acid composite membrane, the number average molecular weight of chitosan is 150-300 KDa, and the deacetylation degree is larger than or equal to 90%; the second composite membrane is a chitosan and chlorinated kojic acid composite membrane, the number average molecular weight of chitosan is 400-800 KDa, and the deacetylation degree is more than or equal to 85%.

According to the invention, the chitosan with the number average molecular weight of 150-300 KDa and 400-800 KDa has good film forming property and antibacterial activity, and the chitosan with the deacetylation degree of more than 85% has more active amino groups and can be tightly combined with kojic acid and chlorinated kojic acid, so that the prepared composite film has good mechanical property and water vapor barrier effect.

Further, in the first composite membrane, the mass ratio of the kojic acid to the chitosan is 0.05-0.15: 0.5-1.2; in the second composite film, the mass ratio of the chlorinated kojic acid to the chitosan is 0.05-0.15: 0.5-1.2.

Further, the first composite film and/or the second composite film also comprise a plasticizer, and the mass ratio of the plasticizer to the chitosan is 0.5-0.8: 0.5-1.2.

Further, the plasticizer is at least one selected from glycerol, sorbitol, polyethylene glycol and stearic acid.

In the present invention, the thickness of the first composite film and the second composite film may be set between several μm and several tens μm, for example, 5 to 90 μm. Furthermore, the thickness of the first composite film is 35.55-39.85 μm, and the thickness of the second composite film is 36.68-41.06 μm.

In the invention, the composite antibacterial preservative film can be prepared by adopting various methods, including but not limited to casting film, extrusion film and the like. Preferably, the first composite membrane and/or the second composite membrane are casting membranes, and have the advantages of high production efficiency, good uniformity of the composite membranes and stable performance.

The invention also provides a preparation method of the chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film, which comprises the following steps:

preparing a chitosan/kojic acid mixed membrane solution and a chitosan/chlorinated kojic acid mixed membrane solution; wherein, in the chitosan/kojic acid mixed membrane liquid, the number average molecular weight of chitosan is 150-300 KDa, and the deacetylation degree is more than or equal to 90%; in the chitosan/chlorinated kojic acid mixed membrane liquid, the number average molecular weight of chitosan is 400-800 KDa, and the degree of deacetylation is more than or equal to 85%;

casting the chitosan/kojic acid mixed membrane solution into a membrane, and drying; and then casting the chitosan/chlorinated kojic acid mixed film liquid on the surface of the chitosan/chlorinated kojic acid mixed film liquid to form a film, and drying to obtain the chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film.

Further, the preparation method of the chitosan/kojic acid mixed membrane solution comprises the following steps:

dissolving chitosan in 1% acetic acid solution, stirring and performing ultrasonic treatment until the chitosan is completely dissolved to obtain 5-12 g/L chitosan solution; adding a plasticizer into the chitosan solution according to the ratio of 0.5-0.8: 0.5-1.2 of the plasticizer to be uniformly stirred for later use;

adding kojic acid into the solution according to the ratio of 0.05-0.15: 0.5-1.2 of kojic acid to chitosan, and stirring for 30-60 min at the stirring speed of 400-800 r/min; carrying out ultrasonic dispersion for 5-10 min, wherein the frequency is 35-50 KHz; and standing for 1-2 h, and carrying out vacuum pressure reduction and defoaming for 10-20 min to obtain the chitosan/kojic acid mixed membrane solution.

Further, the preparation method of the chitosan/chlorinated kojic acid mixed membrane solution comprises the following steps:

dissolving chitosan in 1% acetic acid solution, stirring and performing ultrasonic treatment until the chitosan is completely dissolved to obtain 5-12 g/L chitosan solution; adding a plasticizer into the chitosan solution according to the ratio of 0.5-0.8: 0.5-1.2 of the plasticizer to be uniformly stirred for later use;

adding the chlorinated kojic acid into the solution according to the proportion of 0.05-0.15: 0.5-1.2 of the chlorinated kojic acid and chitosan, and stirring for 45-90 min at the stirring speed of 800-1000 r/min; carrying out ultrasonic dispersion for 10-15 min, wherein the frequency is 35-50 KHz; and standing for 1-2 h, and carrying out vacuum pressure reduction and defoaming for 15-25 min to obtain the chitosan/chlorinated kojic acid mixed membrane solution.

Further, the plasticizer is at least one selected from glycerol, sorbitol, polyethylene glycol and stearic acid.

Further, during film casting, the amount of the chitosan/chlorinated kojic acid composite film liquid is larger than that of the chitosan/kojic acid composite film liquid, preferably, the dosage ratio of the chitosan/chlorinated kojic acid composite film liquid to the chitosan/kojic acid composite film liquid is 1-3: 1, and the composite film has good antibacterial activity. When the ratio exceeds 3:1, the thickness of the membrane is larger, the drying time is longer, while the bacteriostatic activity is highest and the performance of the membrane is best when the ratio is 2: 1.

Further, the drying conditions of the chitosan/kojic acid composite membrane solution are as follows: the drying temperature is 35-55 ℃, and the drying time is 1-2 h; the drying conditions of the chitosan/chlorinated kojic acid composite membrane liquid are as follows: the drying temperature is 55-75 ℃, and the drying time is 2-4 h. In the invention, the chitosan/kojic acid composite membrane liquid and the chitosan/chlorinated kojic acid composite membrane liquid adopt different drying conditions, and the reasons are as follows: in the chitosan/kojic acid composite membrane liquid, the number average molecular weight of the used chitosan is 150-300 KDa, the quantity of the mixed membrane liquid is less, the required drying temperature is lower, and the time is shorter. In the chitosan/chlorinated kojic acid composite membrane liquid, the number average molecular weight of the used chitosan is 400-800 KDa, the viscosity is higher, and the amount of the mixed membrane liquid is more, so that the required drying temperature is higher, and the time is longer.

The invention has the beneficial effects that:

1. the invention uses chitosan which is natural biological preservative, kojic acid and derivatives thereof, the chitosan is natural alkaline polysaccharide extracted from shrimp and crab shells, and the kojic acid is an organic acid generated by aerobic fermentation of certain microorganisms, thus being safe to eat. After the kojic acid is subjected to derivatization, the chlorinated kojic acid with the same antiseptic property can be obtained. At normal temperature, 5-hydroxy-gamma-pyrone group on molecular units of kojic acid and chloro kojic acid can form a tightly combined multilayer film with active amino group in chitosan molecules through electrostatic interaction and hydrogen bonds, so that the tightness degree of all components is enhanced, and the original mechanical property and water vapor barrier property of the chitosan film are further improved. Meanwhile, the composite membrane is prepared by adopting a tape casting method, and the composite membrane has the advantages of high production efficiency, good uniformity and stable performance.

2. The chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film disclosed by the invention has good film-forming property and mechanical property, has a lower water vapor transmission coefficient and good bacteriostatic activity, can avoid a large amount of loss of food water and can achieve a good preservative effect.

3. The chitosan/kojic acid/chlorinated kojic acid composite bacteriostatic preservative film disclosed by the invention is simple and rapid in preparation method, free of any toxic substance and environment-friendly.

Drawings

FIG. 1 is X-ray diffraction patterns of the chitosan film prepared in comparative example 1 and the chitosan/kojic acid/chlorotetracycline composite bacteriostatic preservative film prepared in example 1.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.