FOOD PACKAGING FILMS CONTAINING NATURAL ANTIBACTERIAL COMPONENT

Abstract

The invention relates to edible films, and more particularly to a method for preparing a food packaging film with antibacterial activity. By adding konjac glucomannan and glycerin in starch to obtain a composite film, the aggregation and rearrangement effect among molecules of amylose starch can be weakened, the defects such as high brittleness and low ductility of high-amylose corn starch can be improved, and, since the konjac glucomannan is rich in dietary fiber that is slowly digestible, a low-calorie edible packaging film can be produced by compounding. By adding the embedded product of perilla oil and cyclodextrin in the mixed dispersion of high-amylose corn starch and konjac glucomannan to prepare an active film, the film can have a smoother surface and more perfect and uniform structure, and also, the composite film can have a function of bacteria inhibition.

Claims

1. A method for preparing a food packaging film with antibacterial activity, comprising: sufficiently dissolving cyclodextrin in deionized water to prepare a cyclodextrin solution, and dissolving perilla oil in ethanol to obtain a perilla oil solution; mixing the cyclodextrin solution with the perilla oil solution, and magnetically stirring the reaction mixture under sealing and insulation to embed the perilla oil in the cyclodextrin to obtain an embedded product; filtering the embedded product to remove extra cyclodextrin, freezing and lyophilizing the filtrate, and sealing and storing the lyophilized product in a cool and dark place; dissolving a high-amylose corn starch in deionized water to obtain a starch dispersion, uniformly mixing the starch dispersion followed by stirring under heating to obtain a starch solution; processing the starch solution in an autoclave to gelatinize the high-amylose corn starch to obtain a starch paste; adding konjac glucomannan and glycerin to the starch paste, adding the lyophilized product obtained in step (3), and uniformly mixing the reaction mixture under magnetic stirring to obtain a film-forming liquid; and degassing the film-forming liquid under vacuum, subjecting the degassed film-forming liquid to tape casting to produce a crude film, and quickly drying the crude film by an infrared tunnel dryer to produce a starch-based composite film containing cyclodextrin supermolecules as the food packaging film.

2. The method of claim 1, wherein in step (1), the cyclodextrin solution comprises 2%-6% by weight of cyclodextrin; the perilla oil solution comprises 20%-60% (w/v) of the perilla oil, and is prepared according to a core-to-wall ratio by mass of 1:6-10; and the cyclodextrin is -cyclodextrin or hydroxypropyl--cyclodextrin.

3. The method of claim 1, wherein in step (2), the magnetic stirring is performed at 40-60 C. and 200-220 rpm for 3-5 h; and a volume ratio of the cyclodextrin solution to the perilla oil solution is (90-100):1.

4. The method of claim 1, wherein in step (3), the freezing is performed at 20 to 25 C. for 24-48 h; and the lyophilization lasts for 45-50 h.

5. The method of claim 1, wherein in step (4), the starch dispersion comprises 3%-5% by weight of the high-amylose corn starch; and the stirring under heating is performed at 85-95 C. and 200-220 rpm for 25-35 min.

6. The method of claim 1, wherein in step (5), the gelatinization is performed at 125-130 C. and 2.0 MPa for 25-30 min.

7. The method of claim 1, wherein in step (6), the embedded product is 1%-5% by weight of the konjac glucomannan, glycerin and the starch paste; the magnetic stirring is performed at room temperature and 400-450 rpm for 40-60 min; the konjac glucomannan and the glycerin are respectively 0.2%-0.5% and 1%-2% by weight of the starch paste; in step (7), the degassing is performed at a vacuum degree of 0.08-0.1 MPa for 5-15 min; and the drying is performed at 50-60 C. for 3-5 h.

8. Use of the food packaging film of claim, comprising: applying the food packaging film in the packaging of food.

9. Use of the food packaging film of claim 1, comprising: applying the food packaging film to the packaging of candies, hawthorn rolls, jerky or bread.

Description

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0030] To better understand the purposes, features and advantages of the present invention, the present invention will be further described below by specific embodiments. It is to be noted that the embodiments of the present application and features in the embodiments may be combined if not conflict.

[0031] Many specific details will be explained hereinafter to facilitate the thorough understanding of the present invention. However, the present invention may be implemented in other ways rather than those described here. Therefore, the present invention is not limited to the specific embodiments to be described hereinafter.

Embodiment 1

[0032] This embodiment provides an edible packaging film containing -cyclodextrin supermolecules (a natural antibacterial component), which is used for preserving hawthorn rolls.

[0033] A proper amount of -cyclodextrin powder was dissolved in deionized water to prepare a 2% (percentage by weight, similarly hereinafter) -cyclodextrin solution. The perilla oil solution comprises 25% (w/v) of the perilla oil, and is prepared according to a core-to-wall ratio by mass of 1:8.

[0034] The cyclodextrin solution was mixed with the perilla oil solution in a volume ratio of 90:1, and the reaction mixture was magnetically stirred under sealing at 50 C. and 200 rpm for 4 h.

[0035] The reaction liquid after the embedment was filtered to remove the extra cyclodextrin, and the filtrate was frozen at 20 C. for 24 h and lyophilized for 48 h, and the lyophilized product was sealed and stored in a cool and dark place.

[0036] A high-amylose corn starch was dissolved in deionized water to obtain a 3% starch dispersion, and the starch dispersion was uniformly mixed and then stirred under heating at 90 C. and 200 rpm for 30 min.

[0037] The starch solution was processed in an autoclave at 127 C. and 2.0 MPa for 30 min, to gelatinize the high-amylose corn starch to obtain a starch paste.

[0038] 0.3% (percentage by mass in the starch paste) konjac glucomannan and 1.5% (percentage by mass in the starch paste) glycerin were added to the starch paste, 1% (percentage by mass) embedded product of -cyclodextrin and perilla oil was added, and the reaction mixture was magnetically stirred at 400 rpm for 1 h.

[0039] At the end of stirring, the film-forming liquid was degassed at a vacuum degree of 0.08 Mpa for 10 min, the degassed film-forming liquid was subject to tape casting to produce a crude film, and the crude film was quickly dried by an infrared tunnel dryer at 50 C. for 3 h to produce a starch-based composite film containing -cyclodextrin supermolecules.

[0040] The composite packaging film was prepared in the above way. The obtained starch-based composite packaging film was cut into 108 cm rectangles into which fresh hawthorn rolls were packaged, vacuumized, and sealed at two ends. The hawthorn rolls can be eaten after peeling off the packaging film, or directly without peeling off the packaging film.

Embodiment 2

[0041] This embodiment provides a composite packaging film containing hydroxypropyl--cyclodextrin supermolecules (a natural antibacterial component), which is used for preserving dried pork slices.

[0042] A proper amount of hydroxypropyl--cyclodextrin powder was dissolved in deionized water to prepare a 6% (percentage by weight, similarly hereinafter) hydroxypropyl--cyclodextrin solution. The perilla oil solution comprises 60% (w/v) of the perilla oil, and is prepared according to a core-to-wall ratio by mass of 1:10.

[0043] The cyclodextrin solution was mixed with the perilla oil solution in a volume ratio of 90:1, and the reaction mixture was magnetically stirred under sealing at 50 C. and 200 rpm for 4 h.

[0044] The reaction liquid after the embedment was filtered to remove the extra cyclodextrin, and the filtrate was frozen at 25 C. for 30 h and lyophilized for 48 h, and the lyophilized product was sealed and stored in a cool and dark place.

[0045] A high-amylose corn starch was dissolved in deionized water to obtain a 4% starch dispersion, and the starch dispersion was uniformly mixed and then stirred at 90 C. and 200 rpm for 30 min.

[0046] The starch solution was processed in an autoclave at 127 C. and 2.0 MPa for 30 min, to gelatinize the high-amylose corn starch to obtain a starch paste.

[0047] 0.2% konjac glucomannan and 1.5% glycerin were added to the starch paste, 4% embedded product of hydroxypropyl--cyclodextrin and perilla oil was added, and the reaction mixture was magnetically stirred at 400 rpm for 1 h.

[0048] At the end of stirring, the film-forming liquid was degassed at a vacuum degree of 0.09 Mpa for 10 min, the degassed film-forming liquid was subject to tape casting to produce a crude film, and the crude film was quickly dried by an infrared tunnel dryer at 50 C. for 3.5 h to produce a starch-based composite film containing hydroxypropyl--cyclodextrin supermolecules.

[0049] The composite packaging film was prepared in the above way. The obtained starch-based composite packaging film was cut into 2010 cm rectangles into which dried pork slices in a proper size were packaged, folded on two sides of the film, vacuumized, and sealed by a sealing machine.

Embodiment 3

[0050] This embodiment provides a composite packaging film containing hydroxypropyl--cyclodextrin supermolecules (a natural antibacterial component), which is used for preserving bread.

[0051] A proper amount of hydroxypropyl--cyclodextrin powder was dissolved in deionized water to prepare a 5% (percentage by weight, similarly hereinafter) hydroxypropyl--cyclodextrin solution. The perilla oil solution comprises 55% (w/v) of the perilla oil, and is prepared according to a core-to-wall ratio by mass of 1:9.

[0052] The cyclodextrin solution was mixed with the perilla oil solution in a volume ratio of 100:1, and the reaction mixture was magnetically stirred under sealing at 50 C. and 200 rpm for 4 h.

[0053] The reaction liquid after the embedment was filtered to remove the extra cyclodextrin, and the filtrate was frozen at 20 C. for 48 h and lyophilized for 48 h, and the lyophilized product was sealed and stored in a cool and dark place.

[0054] A high-amylose corn starch was dissolved in deionized water to obtain a 4% starch dispersion, and the starch dispersion was uniformly mixed and then stirred at 90 C. and 200 rpm for 30 min.

[0055] The starch solution was processed in an autoclave at 127 C. and 2.0 MPa for 25 min, to gelatinize the high-amylose corn starch to obtain a starch paste.

[0056] 0.2% konjac glucomannan and 1% glycerin were added to the starch paste, 3% embedded product of hydroxypropyl--cyclodextrin and perilla oil was added, and the reaction mixture was continuously stirred at 400 rpm for 1 h.

[0057] At the end of stirring, the film-forming liquid was degassed at a vacuum degree of 0.08 Mpa for 10 min, the degassed film-forming liquid was subject to tape casting to produce a crude film, and the crude film was quickly dried by an infrared tunnel dryer at 50 C. for 3 h to produce a starch-based composite film containing hydroxypropyl--cyclodextrin supermolecules.

[0058] The composite packaging film was prepared in the above way. The obtained starch-based composite packaging film was cut into 2015 cm rectangles into which pieces of fresh bread or slices of bread were packaged and then sealed.

Comparison Example

[0059] Preparation of the Starch Film

[0060] A high-amylose corn starch was dissolved in deionized water to obtain a 4% (percentage by weight, similarly hereinafter) starch dispersion, and the starch dispersion was uniformly mixed and then stirred under heating at 90 C. and 200 rpm for 30 min.

[0061] The starch solution was processed in an autoclave at 127 C. and 2.0 MPa for 25-30 min.

[0062] 1% glycerin was added, and the reaction mixture was stirred at room temperature and 400 rpm for 1 h.

[0063] At the end of stirring, the film-forming liquid was degassed at a vacuum degree of 0.08 Mpa for 10 min, the degassed film-forming liquid was subject to tape casting to produce a crude film, and the crude film was quickly dried by an infrared tunnel dryer at 50 C. for 3 h, and the film was sealed and stored in a cool and dark place.

[0064] The result of performance tests of the starch-based food packaging films in the Embodiment 3 and the Comparison example is shown in Table 1. A slice of fresh bread is sealed by the active film and stored at 25 C. The change in the amount of microorganism in the bread is measured periodically. The result is shown in Table 2.

[0065] Thickness: for each kind, three films are measured by a micrometer screw gauge at five random points on each film, and an average thickness is calculated.

[0066] Tensile strength and elongation at break: by a method described in ASTM D-882, the starch film and its composite film are cut into 14015 mm strips which are tested by an electronic tensile analyzer in terms of tensile strength and elongation at break.

[0067] Transparency: the light transmittance is measured by an ultraviolet spectrophotometer. The film is cut into strips laminated on the surface of the cuvette, and the light absorptivity of the film is measured at 600 nm. The calculation method is as follows: T=A600/M, where M is the thickness of the film (mm). A higher T indicates a lower transparency of the film.

[0068] Coefficient of moisture permeability: the film is cut into pieces having a diameter of 6 cm, and the coefficient of moisture permeability after 12 h is measured by a moisture permeability analyzer.

TABLE-US-00001 TABLE 1 Performance parameters of the food packaging film Coefficient of moisture Tensile Elongation permeability Thickness strength at break Transparency (g.cm/ Item (m) (MPa) (%) (T) cm2.s.Pa) Embodiment 112 4 10.07 0.25 54.77 0.41 3.31 0.21 2.408 10 12 1 Comparison 89 2 4.34 0.22 15.94 0.15 2.86 0.16 3.439 10 12 example

TABLE-US-00002 TABLE 2 Inspection of microorganism in bread packaged by the starch-based composite active packaging film Storage Total number time Escherichia coli Molds of colony (d) (logCFU/g) (logCFU/g) (logCFU/g) Embodiment 1 2.01 0.08 2.13 0.07 3.10 0.14 1 4 2.25 0.42 3.19 0.35 4.83 0.66 7 2.69 0.12 4.27 0.06 5.21 0.11 Comparison 1 2.73 0.21 3.65 0.13 4.22 0.12 example 4 4.34 0.39 5.18 0.22 6.28 0.04 7 means that no measurement is conducted since the food is obviously moldy or spoilage.

[0069] From the above tables, it may be known by the comparison between the starch-based composite film containing the natural sustained-release antimicrobial agent and the starch film that the food packaging film prepared in the embodiments of the present invention exhibits excellent mechanical properties, slightly decreased transparency, significantly decreased water-blocking properties, and high inhibition against molds. Therefore, when compared to the comparison example, the food packaging film of the present invention has better overall performance.

[0070] The above is only the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any person skilled in the art may make changes or modifications to the mentioned-above technical contents to form equivalent embodiments that are then applied in other fields. However, any simple modifications, equivalent changes and modifications to the above embodiments in accordance with the technical essence of the present invention, without departing from the technical solutions of the present invention, shall be within the protection scope of the technical solutions of the present invention.