CN114058055B

CN114058055B - Production method of degradable frozen food packaging film with photo-thermal antibacterial function

Info

Publication number: CN114058055B
Application number: CN202111460539.1A
Authority: CN
Inventors: 王沛; 王光正; 顾振新; 杨润强; 姜东�
Original assignee: Nanjing Agricultural University
Current assignee: Nanjing Agricultural University
Priority date: 2021-12-02
Filing date: 2021-12-02
Publication date: 2022-07-01
Anticipated expiration: 2041-12-02
Also published as: CN114058055A

Abstract

The invention relates to a production method of a degradable frozen food packaging film with a photothermal antibacterial function, and belongs to the field of food packaging materials. The method is characterized in that wheat bran is taken as a main raw material, extracted by Arabinoxylan (AX), added with a plasticizer and an antibacterial agent, degassed and cast to obtain an AX base membrane; the degradable frozen food packaging film with the photo-thermal antibacterial function is prepared by photo-thermal agent spraying and surface hydrophobic modification. The packaging film produced by the technology has the functions of resisting bacteria, performing photothermal thawing, reducing frozen burning and degrading, and can be applied to frozen food packaging. The invention has the characteristics of easy preparation, low cost, green safety, photo-thermal thawing and the like.

Description

Production method of degradable frozen food packaging film with photo-thermal antibacterial function

One, the technical field

The invention relates to a production method of a degradable frozen food packaging film with a photothermal antibacterial function, and belongs to the field of food packaging materials.

Second, background Art

Plastics are a main material of food packaging at present, but the heavy use and the difficult degradability of the plastic packaging cause serious white pollution and cause great pressure on the ecological environment. Degradable biological packaging materials are the main research direction of food packaging at present. The freezing preservation is a widely applied food preservation means, can inhibit the growth and the propagation of microorganisms and the activity of enzyme in food, and can reserve the nutrient components in the food to the utmost extent, thereby prolonging the shelf life of the food, however, the freezing burning effect caused by freezing can cause the quality degradation of the food, and the development of the frozen food industry is limited. In the case of frozen foods, psychrophilic microorganisms are the major cause of health risks, among which listeria is the most serious. Listeria, one of the most lethal cold-resistant pathogens, can also grow and reproduce at 2-10 ℃, causing a large number of food poisoning and lethal events. In addition, because the steam pressure on the surface of the food is different from the steam pressure of air contacting with the food, ice crystals on the surface of the food are sublimated to cause the water loss of frozen food, the relative humidity of the air in the package is increased, and water vapor on the inner side of the package is condensed into ice when the temperature fluctuates, so that the freezing burning effect can be caused and the food is adhered to a packaging material after a long time.

The wheat bran is rich in dietary fiber, wherein the Arabinoxylan (AX) can be biologically degraded, and the wheat bran has the advantages of safety, environmental protection, low cost and the like, and has good film-forming property and mechanical property after being added with a plasticizer. The ferulic acid hexyl ester is a phenolic acid ester with bioactivity, has strong inhibiting effect on Listeria monocytogenes, and has concentration and time effect. Meanwhile, the phenolic acid ester also has an antioxidation effect. Dopamine is a substance with good biocompatibility, can undergo oxidative autopolymerization in an alkaline solution to form polydopamine, and is firmly adhered to the surface of an object. In addition, polydopamine not only has super-strong adhesion performance, but also can be used as a photo-thermal agent for converting light energy into heat energy under the irradiation of near infrared light. The listeria monocytogenes is sensitive to heat and is matched with the antibacterial property of the hexyl ferulate, so that the purposes of unfreezing and synergistic sterilization are realized. The polydopamine nanoparticle solution is irradiated by near infrared light, so that the temperature of the solution can be increased to be close to 50 ℃ within 5 minutes. By alkylating SiO with different particle sizes₂Can construct a hydrophobic structure similar to a lotus rough surface, and is added with alkylated SiO₂The low energy alkyl group can form a membrane surface with good hydrophobicity, reduce the adhesion of food and package, and reduce the effect of frozen burning.

The patent (publication No. CN110343282A, 10.18.2019) discloses a super-hydrophobic nano cellulose fiber membrane, which is prepared by preparing a membrane material by using cellulose nano fibers and repeatedly immersing the cellulose fiber membrane into modified super-hydrophobic nano SiO for multiple times₂To obtain a nano cellulose membrane with super hydrophobicity. However, the film is hydrophobic only and does not have resistanceBacterial and photothermal properties. The invention adds the functions of antibacterial ferulic acid hexyl ester and photo-thermal thawing of polydopamine on the basis of a hydrophobic surface, and also has the advantages of environmental protection, low manufacturing cost, simple operation and the like. The patent (publication No. CN207859654U, published 2018, 9 and 14) discloses a novel antibacterial frozen food packaging film, which is formed by superposing a freezing-proof layer, a multi-layer co-extrusion antibacterial layer, a flexible layer, a mechanical strength carrier layer and a cleaning functional layer to obtain an antibacterial frozen food packaging material. The invention directly adds the antibacterial agent into the AX basal membrane, can realize the required antibacterial and freezing requirements only by modifying the surface, and has the advantages of low cost and simple preparation.

The method comprises the steps of taking AX extracted from wheat bran as a main raw material, adding a plasticizer and an antibacterial agent, degassing, and casting a film to obtain an AX base film; spraying a photo-thermal agent on the AX base film, and fixing silicon dioxide to prepare the degradable frozen food packaging film with the photo-thermal antibacterial function. The film has the functions of degradation, antibiosis, photo-thermal thawing, freezing and burning reduction and the like, and can be used as a packaging material for frozen food.

Third, the invention

Technical problem

The invention aims to provide a production method of a degradable frozen food packaging film with a photo-thermal antibacterial function, which realizes the functions of antibiosis, photo-thermal thawing, freezing burn reduction and degradability by AX base film preparation, photo-thermal agent spraying and surface hydrophobic modification.

Technical scheme

The technical scheme of the invention is summarized as follows: taking AX extracted from wheat bran as a main raw material, adding a plasticizer and an antibacterial agent, degassing, and casting to obtain an AX base membrane; the packaging film for frozen food is prepared by spraying a photothermal agent polydopamine on an AX base film and fixing silicon dioxide, and the method comprises the following specific steps:

(1) preparation of an AX base film: according to a known method, wheat bran is subjected to starch removal, alkali extraction, deproteinization, enzyme treatment, dialysis, enzymolysis, alcohol precipitation grading and secondary enzymolysis dialysis to obtain AX; dissolving AX in pure water, and uniformly mixing with plasticizer glycerol and antibacterial agent hexyl ferulate, wherein the final mass volume concentrations of the AX, the glycerol and the hexyl ferulate are respectively 1-2%, 10-30% and 1-5%, preferably the mass volume concentrations of the AX, the glycerol and the hexyl ferulate are respectively 2%, 30% and 5%, and the mechanical property and the antibacterial property of the obtained membrane are optimal. Stirring at room temperature at 120rpm for 15min, mixing, degassing for 30min to eliminate bubbles; pouring the degassed solution into a mold, and drying at 40-60 ℃ for 6-8 h to obtain an AX base membrane;

(2) photo-thermal agent spraying: preparing a dopamine hydrochloride aqueous solution with the mass volume concentration of 0.3% -0.6%, adjusting the pH value to 8.0-10.0, standing at room temperature for 1min, preferably, the dopamine hydrochloride mass volume concentration is 0.5%, and the pH value is 9.5, so that the poly-dopamine coating is formed at the fastest speed, and the photo-thermal effect is optimal. Filling the dopamine hydrochloride aqueous solution into a spraying device, carrying out rotary spraying on an AX base membrane for 1min at the speed of 6000rpm, repeatedly washing the base membrane for 2-3 times by using pure water, drying in an oven at 40 ℃ for 7-8 h, and repeating the steps for 2-3 times;

(3) surface hydrophobic modification: bisphenol a glycidyl ether (DGEBA) and diaminodiphenylmethane (DDM) were mixed in a 2:1 molar ratio to ensure complete reaction. Alkylating SiO with the particle size of 40-60 nm and 200-500 nm₂Dispersing in the mixture of epoxy resin and ethanol to form double SiO layers on the surface of the film₂And (5) micro-nano structure. Wherein the SiO has a particle size of 200-500 nm and a particle size of 40-60 nm₂The mass volume concentration of the organic acid is 1-2% and 2-4% respectively. Preferably 50nm SiO with the mass volume concentration of 1.5 percent and 300nm SiO with the mass volume concentration of 2.5 percent₂The hydrophobicity of the film is optimal at this time. And (3) carrying out ultrasonic treatment on the dispersion liquid for 25-40 min, spraying the dispersion liquid on the treated membrane at the speed of 1200-1700 rpm, and then drying the membrane in an oven at the temperature of 60 ℃ for 4-5 h.

Advantageous effects

Compared with the prior art, the invention has the following advantages:

(1) by preparing the hydrophobic surface, the adsorption of ice crystals is hindered, and the freezing burning effect is reduced;

(2) the photothermal agent is sprayed on the membrane to realize the effects of accelerating food thawing and inhibiting proliferation of food-borne pathogenic bacteria;

(3) the antibacterial agent of hexyl ferulate is added to inhibit the growth and propagation of Listeria in frozen food in a targeted manner, so that the safety of the frozen food is guaranteed.

Fourth, detailed description of the invention

Example 1

According to a known method, wheat bran is subjected to starch removal, alkali extraction, deproteinization, enzyme treatment, dialysis, enzymolysis, alcohol precipitation grading and secondary enzymolysis dialysis to obtain AX; dissolving AX in pure water according to the mass volume concentration of 2%, adding 30% of plasticizer glycerol and 5% of antibacterial agent ferulic acid hexyl ester into the solution according to the mass volume concentration, stirring at room temperature at 120rpm for 15min, fully mixing uniformly, and degassing for 30min until bubbles are completely eliminated; and pouring the degassed solution into a mold, and drying at 40-60 ℃ for 6-8 h to obtain the AX base membrane. Preparing dopamine hydrochloride aqueous solution with mass volume concentration of 0.5%, adjusting pH to 9.5, and standing at room temperature for 1 min. And (3) putting the dopamine hydrochloride aqueous solution into a spraying device, carrying out rotary spraying on the AX base membrane for 1min at the speed of 6000rpm, repeatedly washing the base membrane for 2-3 times by using pure water, drying in an oven at 40 ℃ for 7-8 h, and repeating the steps for 2-3 times. Bisphenol a glycidal aldehyde (DGEBA) and diaminodiphenylmethane (DDM) were mixed in a molar ratio of 2:1 to ensure complete reaction. Selecting 50nm alkylated SiO with mass volume concentration of 1.5% and 300nm with mass volume concentration of 2.5%₂Dispersed in a mixture of epoxy resin and ethanol. And (3) carrying out ultrasonic treatment on the dispersion liquid for 25-40 min, spraying the dispersion liquid on the treated membrane at the speed of 1200-1700 rpm, and then drying the membrane in a 60 ℃ drying oven for 4-5 h to obtain the target membrane material. The film can be heated to 50 ℃ within 5min under the irradiation of near infrared light; the antibacterial agent can kill more than 90% of Listeria monocytogenes within 10 h; the water contact angle of the film surface can reach 140 degrees.

Example 2

Wheat bran AX was extracted as in example 1. AX, glycerol and hexyl ferulate were mixed at mass volume concentrations of 1%, 10% and 1%, degassed, film-cast and dried in the same manner as in example 1. Preparing dopamine hydrochloride aqueous solution with mass volume concentration of 0.3%, and adjusting the pH value to 8.0. The spraying and drying processes were the same as in example 1. The mixture of bisphenol A glycidal (DGEBA) and diaminodiphenylmethane (DDM) was as in example 1. SelectingTaking 40nm alkylated SiO with mass volume concentration of 1% and 200nm and mass volume concentration of 2%₂Dispersing, ultrasonic treatment, spraying and drying were the same as in example 1. The film can be heated to 30 ℃ within 5min under the irradiation of near infrared light; the antibacterial agent can kill more than 90% of Listeria monocytogenes within 16 h; the water contact angle of the film surface can reach 120 degrees.

Example 3

Wheat bran AX was extracted as in example 1. AX, glycerol and hexyl ferulate were mixed at 2%, 20% and 3% by mass volume, degassed, film-cast and dried as in example 1. Preparing dopamine hydrochloride aqueous solution with mass volume concentration of 0.6%, and adjusting the pH value to 10.0. The spraying and drying processes were the same as in example 1. The mixture of bisphenol A glycidal (DGEBA) and diaminodiphenylmethane (DDM) was as in example 1. Selecting 60nm alkylated SiO with mass volume concentration of 2% and 500nm and mass volume concentration of 4%₂Dispersing, ultrasonic treatment, spraying and drying were the same as in example 1. The film can be heated to 40 ℃ within 5min under the irradiation of near infrared light; the antibacterial agent can kill more than 90% of Listeria monocytogenes within 12 h; the water contact angle of a hydrophobic surface can reach 130 degrees.

The embodiments of the present invention have been described in detail above, but this is only an example for easy understanding and should not be construed as limiting the scope of the present invention. Also, various equivalent changes and substitutions which are possible for those skilled in the art can be made according to the technical solution of the present invention and the description of the preferred embodiment thereof, and all such changes and substitutions shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for producing degradable frozen food packaging film with photo-thermal antibacterial function is characterized in that Arabinoxylan (AX) is extracted from wheat bran, a plasticizer and an antibacterial agent are added, and AX base film is obtained after degassing and film casting; the degradable frozen food packaging film with the photo-thermal antibacterial function is prepared by photo-thermal agent spraying and surface hydrophobic modification, and specifically comprises the following steps:

(1) preparation of an AX base film: removing starch from wheat bran, performing alkali extraction, deproteinizing, performing enzyme treatment, dialyzing, performing enzymolysis, performing alcohol precipitation grading, and performing secondary enzymolysis and dialysis to obtain AX; dissolving AX in pure water, uniformly mixing with plasticizer glycerol and antibacterial agent hexyl ferulate, wherein the final mass volume concentrations of AX, glycerol and hexyl ferulate are respectively 1-2%, 10-30% and 1-5%, stirring at room temperature at 120rpm for 15min, fully mixing, and degassing for 30min to completely eliminate bubbles; pouring the degassed solution into a mold, and drying at 40-60 ℃ for 6-8 h to obtain an AX base membrane;

(2) photo-thermal agent spraying: preparing a dopamine hydrochloride aqueous solution with the mass volume concentration of 0.3-0.6%, adjusting the pH value to 8.0-10.0, and standing at room temperature for 1 min; rotationally spraying dopamine hydrochloride aqueous solution on an AX base membrane at the speed of 6000rpm for 1min, repeatedly washing the base membrane with pure water for 2-3 times, drying in an oven at 40 ℃ for 7-8 h, and repeating the steps for 2-3 times;

(3) surface hydrophobic modification: mixing bisphenol A glycidyl ether (DGEBA) and diaminodiphenylmethane (DDM) in a molar ratio of 2:1 to ensure complete reaction to produce an epoxy resin; alkylating SiO with the particle size of 40-60 nm and 200-500 nm₂Dispersing in a mixture of epoxy resin and ethanol, wherein the SiO has a particle size of 200-500 nm and a particle size of 40-60 nm₂The mass volume concentration of the mixture is respectively 1-2% and 2-4%; and (3) carrying out ultrasonic treatment on the dispersion liquid for 25-40 min, spraying the dispersion liquid on the treated membrane at the speed of 1200-1700 rpm, and then drying the membrane in an oven at the temperature of 60 ℃ for 4-5 h.

2. The use of the degradable frozen food packaging film with a photothermal antibacterial function according to claim 1 for frozen food packaging.