Composite antibacterial absorbent pad loaded with thirteen essential oil and application of composite antibacterial absorbent pad in preservation of chilled meat

Abstract

The invention relates to the technical field of chilled meat preservation, in particular to a compound antibacterial absorbent pad loaded with thirteen essential oil and application of the compound antibacterial absorbent pad in chilled meat preservation. The invention provides a thirteen-essential-oil-loaded composite antibacterial absorbent pad with a multi-layer structure. The thirteen-essential-oil-loaded composite antibacterial absorbent pad comprises an inner-layer film, a middle-layer film and an outer-layer film which are sequentially stacked, wherein the inner layer film comprises peach gum and thirteen essential oil; the middle layer film comprises peach gum, zein and thirteen essential oil; the outer layer film comprises zein and thirteen essential oil. The invention provides the tray packaging absorbent pad which is high in safety, high in utilization rate of thirteen essential oil, good in antibacterial and fresh-keeping effect on food materials such as chilled meat which are extremely easy to cause juice loss and spoilage in the processing, storage and transportation stages, pleasant in smell and excellent in comprehensive performance.

Description

Technical Field

[0001] The invention relates to the technical field of cold fresh meat preservation, in particular to a composite antibacterial water-absorbing pad loaded with thirteen spices essential oil and application thereof in cold fresh meat preservation. Background Art

[0002] Due to its high nutritional value and high water activity, fresh meat is prone to juice loss and spoilage during processing, storage and transportation. If it is not treated with any preservation method, its quality can only be maintained for 3 days. Quality deterioration not only harms the health of consumers, but also causes huge economic losses to the pork industry. Commonly used chemical preservatives for fresh meat preservation include potassium sorbate, sodium benzoate, sodium dehydroacetate, sodium diacetate, etc. Although chemical preservatives can effectively delay the deterioration of meat, they still cannot effectively solve the quality deterioration problem caused by juice loss, and consumers are also resistant to chemical preservatives. In recent years, with the development of the environmentally friendly packaging materials industry, the application of natural bioactive compounds in the packaging of fresh agricultural products has received increasing attention. The incorporation of natural bioactive compounds into packaging materials can provide packaging materials with a variety of functional effects, such as antioxidant and antibacterial. The advantages of natural bioactive compounds over synthetic compounds are better safety and easier acceptance by consumers, which has been widely confirmed.

[0003] Thirteen spices essential oil (TSEO) is an essential oil extract made from thirteen traditional natural spices (including pepper, angelica, galangal, cloves, etc.) according to the seasoning formula of "Thirteen Spices" (see Figure 1 ). Among them, the formula of the seasoning "Thirteen Spices" can be: cardamom, amomum, nutmeg, cinnamon, cloves, prickly ash, star anise, cumin, costus root, angelica dahurica, galangal, dried ginger, and black pepper. The strong antibacterial ability of Thirteen Spices Essential Oil (TSEO) mainly comes from the synergistic effect of the various components in the essential oil, and the volatile components of Thirteen Spices Essential Oil (TSEO) can generate an antibacterial "atmosphere" on the surface of food without being directly added to the food, and have a significant inhibitory effect on common microorganisms in the environment. However, the antibacterial property of essential oils is inseparable from their chemical stability. When essential oils are exposed to an environment with oxygen, light and heat, most of the components are easily oxidized and lose their original antibacterial activity. This also limits the application of Thirteen Spices Essential Oil in antibacterial packaging of food.

[0004] It is of great significance to construct a suitable thirteen-spice essential oil loading system to fully exert and prolong its preservation effect.

[0005] Peach gum (PG) is produced by the fruit and trunk of peach trees when they are mechanically damaged or invaded by microorganisms. Peach gum is composed of complex polysaccharides, containing a large amount of arabinose, xylose, galactose, glucose and uronic acid. It is a pure natural and renewable polysaccharide colloid substance with abundant sources and low cost. Peach gum has good film-forming properties, swelling properties, biocompatibility, degradability, adsorption properties, safety and non-toxicity, and is an excellent carrier material. In addition, peach gum also shows high free radical scavenging activity and high reducing ability. At the same time, it has high antibacterial activity against Bacillus subtilis, Staphylococcus aureus and Escherichia coli, which is beneficial to repair oxidative skin damage. The application of pure peach gum film is affected by its hydrophilicity, which makes the barrier properties of pure peach gum film and its derivative films poor.

[0006] Zein (ZN) is a hydrophobic corn protein rich in non-polar amino acids and has excellent film-forming properties. It is a biocompatible, biodegradable, non-toxic and harmless natural edible biological packaging material. The zein film formed by the casting method has hydrophobicity, UV resistance, aroma and gas barrier, moisture and oil barrier, and antibacterial properties. However, the film formed by single zein is opaque in appearance and exhibits brittle mechanical properties even with the help of plasticizers.

[0007] CN108587189A discloses a zein / peach gum composite cling film, and its preparation method comprises: (1) dissolving zein and peach gum powder in a composite liquid of ethanol and 1,2-propylene glycol, and then ultrasonically degassing to obtain an edible composite film liquid; (2) pouring, drying and filming the edible composite film liquid to obtain a zein / peach gum composite edible cling film. The zein / peach gum composite cling film has good moisture barrier and oxygen barrier properties (i.e., excellent barrier properties), but since it is an integrated zein / peach gum composite cling film prepared by a "one-pot method", zein and peach gum are uniformly dispersed in the film, and excellent barrier properties inevitably lead to poor water absorption performance; it cannot be used as a water-absorbing pad, cannot absorb the juice exuded from the cold fresh meat during transportation and storage, and cannot prevent the formation of condensed water during the storage of the cold fresh meat, which will cause the inside of the package to be damp, which is not conducive to extending the shelf life of the meat. In addition, the zein / peach gum composite cling film uses 1,2-propylene glycol as a solvent. However, 1,2-propylene glycol is a low-toxic substance and may cause kidney problems when added to food, and some countries have banned its use in the food industry.

[0008] The document "Chen Xia. Construction and Activity Regulation of Zein / Gelatin Edible Films [D]. Guangdong: South China University of Technology, 2020" discloses the use of zein (Zein) and gelatin (Gelatin) with complementary functional properties as film-forming matrices to construct a multilayer film system (Z-ZG-G) and a composite film system (ZG), develop new active packaging materials, and apply them to the preservation of fresh-cut fruits. Fresh-cut fruit experiments have shown that multilayer functional films loaded with tea polyphenols (TP) show good preservation effects in controlling water loss, preventing rapid browning, and inhibiting microbial growth. However, the document only studies the effect of Z-ZG-G loaded with tea polyphenols (TP) on the preservation of fresh-cut fruits, and does not verify its effect on the preservation of cold fresh meat. The present invention finds that when the method of the document is used to prepare a Z-ZG-G multilayer structure composite antibacterial absorbent pad loaded with thirteen spice essential oil (TSEO), the hydrophilic inner layer TSEO / G reserve solution is thick when the film is cast into a film, and it is impossible to cast into a film (such as Fig.16 As shown), it is ultimately impossible to prepare Z-TSEO / ZG loaded with thirteen spices essential oil. 1:2 -TSEO / G multilayer functional membrane. In addition, the membranes made of the hydrophobic outer layer Zein stock solution (Z) and the hydrophilic inner layer TSEO / Gelatin stock solution (TSEO / G) were unevenly distributed (e.g. Fig.18 and Fig.17 As shown), the mechanical strength is low and it is difficult to use as a water absorbent pad; at the same time, the solvent 80% glacial acetic acid used in the method of the document is highly irritating and corrosive. Excessive intake or improper use may lead to health risks, such as irritation of the oral and digestive tract mucosa, skin irritation or allergic reaction, and the present invention has found that the Z-ZG-G multilayer structure composite antibacterial water absorbent pad loaded with thirteen spices essential oil (TSEO) prepared by the method of the document has a strong irritating smell of glacial acetic acid. When it is used for the preservation of fresh pork, it will affect the smell experience of fresh pork, which is not conducive to consumers' acceptance of use. Summary of the invention

[0009] [Technical issues]

[0010] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a tray packaging absorbent pad which has high safety, high utilization rate of thirteen-spice essential oil, better antibacterial and fresh-keeping effect for food materials such as cold fresh meat that are very likely to lose juice and spoil during processing, storage and transportation, pleasant smell and excellent comprehensive performance.

[0011] [Technical solution]

[0012] On the one hand, a multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil is provided, which comprises an inner layer film, an intermediate layer film and an outer layer film stacked in sequence; wherein:

[0013] The inner membrane includes peach gum and thirteen-spice essential oil;

[0014] The middle membrane includes peach gum, zein and thirteen-spice essential oil;

[0015] The outer membrane includes zein and zein essential oil.

[0016] In some embodiments, the solvent used for the inner layer film is water; the solvent used for the middle layer film and the outer layer film is ethanol aqueous solution.

[0017] On the other hand, a method for preparing a multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil is also provided, which comprises the following steps:

[0018] (1) Preparation of membrane-forming solution:

[0019] S01, mixing peach gum powder and water in a mass ratio of (2.5-10):100 to prepare a peach gum aqueous solution;

[0020] S02, mixing zein powder and ethanol aqueous solution at a ratio of (2.5-10) g:100 mL to prepare zein ethanol aqueous solution;

[0021] S1, preparing inner membrane liquid: mixing thirteen spices essential oil and the peach gum aqueous solution in a ratio of (0.5-2.5) mL:100 g to prepare inner membrane liquid;

[0022] S2, preparing an intermediate layer membrane liquid: mixing the peach gum aqueous solution and the zein ethanol aqueous solution at a volume ratio of 1:1 to obtain a mixed solution containing peach gum and zein; mixing thirteen spices essential oil with the mixed solution containing peach gum and zein at a ratio of (0.5-2.5) mL:100 g to prepare an intermediate layer membrane liquid;

[0023] S3, preparing outer membrane solution:

[0024] The thirteen spices essential oil and the zein ethanol aqueous solution are mixed at a ratio of (0.5-2.5) mL:100 g to prepare an outer membrane liquid;

[0025] (2) Preparation of absorbent pad: The inner layer membrane liquid, the middle layer membrane liquid and the outer layer membrane liquid are homogenized and degassed and then cast layer by layer. The multilayer membrane product formed is the aforementioned multilayer structure composite antibacterial absorbent pad loaded with thirteen spices essential oil.

[0026] In some embodiments, the volume fraction of ethanol in the ethanol aqueous solution in step S02 is 60-90%.

[0027] In some embodiments, the particle size of the peach gum powder in step S01 is 80-200 mesh.

[0028] In some embodiments, the mixing in any of step S1, step S2 or step S3 is achieved by stirring at a temperature of 25 to 60° C. and a rotation speed of 100 to 200 r / min.

[0029] In some embodiments, the mixing time in any of step S1, step S2 or step S3 is 30 to 60 minutes.

[0030] In some embodiments, the homogenization parameters in step (2) are: homogenization at 8000-10000 rpm for 1-5 minutes.

[0031] In some embodiments, the homogenization in step (2) is performed using a high-speed homogenizer.

[0032] In some embodiments, the degassing in step (2) is performed by ultrasonic degassing, and the degassing parameters are: 40kHz, 700W degassing for 10 to 30 minutes.

[0033] In some embodiments, the method for drying the film after the layer-by-layer casting in step (2) comprises drying at 25 to 50° C. for 4 to 8 hours.

[0034] In some embodiments, the drying method of the film after the layer-by-layer casting in step (2) comprises at least one of hot air drying and / or fume hood drying.

[0035] Wherein, the fume hood drying method is: placing the film liquid after casting in a fume hood and drying it naturally at room temperature for 4 to 8 hours.

[0036] On the other hand, the invention provides the use of the aforementioned multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil in the packaging of fresh meat.

[0037] In some embodiments, the application is packaged in trays.

[0038] In some embodiments, the tray of the tray packaging is sealed with a sealing film and stored at 0-10°C.

[0039] [Beneficial Effects]

[0040] The present invention provides a tray packaging absorbent pad with high safety, high utilization rate of thirteen spices essential oil, better antibacterial and fresh-keeping effect for food materials such as cold fresh meat that are very easy to lose juice and spoil during processing, storage and transportation, pleasant smell and excellent comprehensive performance. Specifically:

[0041] The main raw materials used in the present invention include peach gum, thirteen spices essential oil and zein, which are all natural plant ingredients, safe, non-toxic and biodegradable, highly safe, environmentally friendly and pollution-free. In particular, the antibacterial ingredient thirteen spices essential oil does not cause harm to consumers' health and the natural environment, and is more easily accepted by consumers.

[0042] The antibacterial water-absorbing pad prepared by the present invention has a thirteen-flavor smell, which is pleasant and is more easily accepted by consumers than the fresh-keeping packaging products with strong pungent smell in the prior art.

[0043] The present invention introduces peach gum with high water absorption and swelling, thirteen spices essential oil with strong antibacterial performance and zein with high barrier properties as raw materials of composite antibacterial absorbent pad, with peach gum loaded with thirteen spices essential oil as inner layer membrane, zein loaded with thirteen spices essential oil as outer layer membrane, and composite membrane of peach gum\zein with different proportions efficiently loaded with thirteen spices essential oil as middle layer membrane, and the above raw material components are made into composite antibacterial absorbent pad by layer-by-layer casting method. The peach gum inner layer membrane absorbs water and swells, and the zein outer layer membrane has high barrier properties. According to different proportions of peach gum\zein middle layer membrane, the loading rate of thirteen spices essential oil is high (high retention rate), and the film-forming advantages of peach gum and zein are combined to prepare multilayer membrane. By adjusting the composition of membrane matrix and the loading strategy of natural bioactive compound thirteen spices essential oil (as antibacterial component), a water-absorbing pad with adjustable water barrier performance, swelling rate and prolonged antibacterial property is obtained, which can control the exudation of cold fresh meat juice and release ten in tray packaging. The three-spice essential oil forms an antibacterial "atmosphere". The thirteen-spice essential oil is a pure, natural, safe, non-toxic, and highly effective antibacterial spice essential oil. Each layer of the composite antibacterial absorbent pad of the present invention contains the antibacterial thirteen-spice essential oil. The composite antibacterial absorbent pad of the present invention contains the antibacterial thirteen-spice essential oil. The migration and diffusion of the thirteen-spice essential oil in the multilayer film can kill or inhibit microorganisms that contaminate the fresh meat during the packaging, storage, transportation, and circulation processes. The thirteen-spice essential oil has a significant antibacterial effect on the fresh meat, has high antibacterial activity, can effectively extend the shelf life of the fresh meat, and has a good preservation effect on the fresh meat. The present invention adopts peach gum with high water absorption and swelling property as the inner layer film, which can fully contact with meat, consume water, form an inner gel layer with water absorption and swelling, and help the high-load essential oil in the middle layer film to diffuse inward, and the preservation effect is good; the inner layer film and the middle layer film with peach gum can absorb juice and secretion in time, control the exudation of cold fresh meat juice, and help to better maintain the color of cold fresh meat; the outer layer film using high barrier zein as the water absorption pad can reduce the water loss of cold fresh meat, and can achieve the water retention and color protection of cold fresh meat. The zein in the outer layer film and the middle layer film has a unidirectional barrier property to the thirteen spices essential oil, which promotes the inward release of the thirteen spices essential oil on the one hand, and isolates the adverse external environmental conditions on the other hand.

[0044] Compared with a single-layer peach gum film or a single-layer zein film, the multi-layer antibacterial water-absorbing pad of the present invention can greatly improve the retention rate of thirteen-spice essential oil, thereby improving the utilization rate of thirteen-spice essential oil, reducing production costs, and improving the antibacterial and fresh-keeping effects.

[0045] Compared with the existing integrated zein / peach gum composite cling film prepared by the "one-pot method", the multi-layer antibacterial water-absorbing pad of the present invention has an inner layer membrane and an intermediate layer membrane of peach gum that can absorb juice and secretions in time, control the exudation of cold fresh meat juice, and is conducive to better maintaining the color of cold fresh meat and improving the preservation effect; at the same time, the peach gum inner layer membrane absorbs juice to form an internal gel layer that absorbs water and swells, which helps the high-load thirteen spices essential oil in the intermediate layer membrane to diffuse inward, further extending the shelf life of the meat. The multi-layer antibacterial water-absorbing pad of the present invention has a better antibacterial and fresh-keeping effect for cold fresh meat, which is very easy to lose juice and spoil during processing, storage and transportation.

[0046] The multi-layer antibacterial water-absorbing pad of the present invention realizes efficient loading of thirteen-spice essential oil under a specific ratio by combining specific materials such as peach gum and zein with specific solvents. At the same time, the prepared antibacterial water-absorbing pad has excellent comprehensive performance: excellent thermal stability and excellent density, the inner layer film has the ability to efficiently absorb juice, and can also be stably formed after absorbing juice, the composite film structure does not disintegrate, has excellent mechanical properties, and has low water vapor permeability on both sides, and can meet the use requirements of being used as a water-absorbing pad in the preservation of fresh meat.

[0047] The multi-layer antibacterial water-absorbing pad of the present invention is used in the packaging of fresh meat, adopts tray packaging, has a simple process, and has the characteristics of wide application range, strong antibacterial property, stable performance, low production cost and biodegradability in the antibacterial preservation of fresh meat. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the preparation process of a multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil provided by the present invention;

[0049] Figure 2 It is a comparison diagram of infrared spectra of the antibacterial water-absorbing pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2;

[0050] Figure 3 It is a comparison diagram of the X-ray diffraction patterns of the antibacterial absorbent pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2;

[0051] Figure 4 It is a comparison diagram of the thermodynamic spectra of the antibacterial absorbent pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2;

[0052] Figure 5The following is a comparison of the appearance of the antibacterial absorbent pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2;

[0053] Figure 6 The microstructure diagrams of the surfaces and cross sections of the antibacterial absorbent pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2 are compared;

[0054] Figure 7 The results of water swelling, water solubility and volatility mass fraction of the water absorbent pads in Examples 1 to 3 and Comparative Examples 1 to 2 are as follows;

[0055] Figure 8 is the retention rate of TSEO of the absorbent pads in Examples 1 to 3 and Comparative Examples 1 to 2;

[0056] Fig. 9 is the release rate of TSEO of the absorbent pad in Examples 1 to 3 and Comparative Examples 1 to 2 in 80% glycerol (aqueous food simulant);

[0057] Fig.10 is the release rate of TSEO of the absorbent pad in Examples 1 to 3 and Comparative Examples 1 to 2 in n-hexane (oil-containing food simulant);

[0058] Fig.11 The antibacterial test results of the absorbent pads in Examples 1 to 3 and Comparative Examples 1 to 2 are shown;

[0059] Fig.12 The TVC results of fresh pork using the absorbent pad of the present invention at different storage periods;

[0060] Fig.13 The pH results of fresh pork at different storage periods using the absorbent pad of the present invention are shown;

[0061] Fig.14 The morphology of the surface (the side not in direct contact with the absorbent pad) of fresh pork using the absorbent pad of the present invention at different storage periods;

[0062] Fig.15 The morphology of the bottom (the side in direct contact with the absorbent pad) of fresh pork using the absorbent pad of the present invention at different storage periods;

[0063] Fig.16 Preparation of TSEO / G hydrophilic inner layer TSEO / Gelatin membrane (TSEO / G) of Comparative Example 3;

[0064] Fig.17 TSEO / ZG of Comparative Example 3 1:2 Intermediate layer TSEO-Zein / Gelatin membrane (TSEO / ZG 1:2 ) preparation;

[0065] Fig.18 Preparation of the hydrophobic outer layer Zein membrane of Comparative Example 3;

[0066] Fig.19 The intermediate layer soluble starch Zein / Soluble starch stock solution (ZN / SS 1:3 ) preparation;

[0067] Fig. 20 The intermediate layer of sodium alginate Zein / Sodium Alginate stock solution (ZN / SA 1:3 ) preparation;

[0068] Fig.21 The intermediate layer pullulan Zein / Pullulan stock solution (ZN / PL 1:3 ) preparation;

[0069] Fig. 22 The intermediate layer of the Zein / Gelatin stock solution (ZN / GE 1:3 ) preparation. DETAILED DESCRIPTION

[0070] The present invention will be further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement it with reference to the text of the specification. It should be understood that the terms such as "having", "including" and "comprising" used herein do not exclude the presence or addition of one or more other elements or their combinations. It should also be noted that the experimental methods described in the following examples are conventional methods unless otherwise specified, and the reagents and materials, unless otherwise specified, can be obtained from commercial sources.

[0071] The present invention provides a method for preparing a composite antibacterial water-absorbing pad loaded with thirteen spices essential oil for preserving fresh cold meat, comprising the following steps:

[0072] The aqueous solution containing peach gum (PG), zein (ZN) and twelfth spices essential oil (TSEO) is stirred at a speed of 100-200r / min and a temperature of 25-60°C for 30-60 minutes to prepare a film-forming liquid; then the film-forming liquid is homogenized at 8000-10000rpm by a high-speed homogenizer for 1-5 minutes; after ultrasonic (40kHZ, 700W) degassing for 10-30 minutes, the film-forming liquid is cast layer by layer (temperature 25-50°C, drying for 4-8 hours), and the formed multilayer film product is a composite antibacterial water-absorbing pad loaded with twelfth spices essential oil. Figure 1 shown.

[0073] The method for preparing the inner layer film of the composite antibacterial water-absorbing pad loaded with thirteen spices essential oil comprises the following steps:

[0074] (1) stirring an aqueous solution containing PG and TSEO at a speed of 100 to 200 r / min and a temperature of 50 to 60° C. for 40 to 60 minutes to prepare a membrane-forming solution;

[0075] (2) homogenizing the film-forming liquid at 8000-10000 rpm for 1-5 minutes using a high-speed homogenizer;

[0076] (3) After degassing by ultrasonic wave (40 kHz, 700 W) for 10 to 30 minutes, the film-forming liquid is cast (temperature 25 to 50° C., drying for 4 to 8 hours) to form a film, and the formed film product is the inner layer film of the peach gum-based multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil.

[0077] In some embodiments of the present invention, preferably, in step (1), the method for preparing the aqueous solution containing PG and TSEO is as follows: grind the purchased large PG particles into powder, pass through a 100-mesh sieve, and then add water to prepare a PG aqueous solution, wherein the mass ratio of PG powder to water in the PG aqueous solution is (2.5-10):100; mix TSEO with the aforementioned PG aqueous solution to prepare an inner membrane liquid, wherein the usage ratio of TSEO to the aforementioned PG aqueous solution is (0.5-2.5) mL:100 g.

[0078] In some embodiments of the present invention, preferably, in step (3), the drying method is hot air drying or fume hood drying, wherein the fume hood drying method is: placing the cast film liquid in a fume hood and drying it naturally at room temperature for 4 to 8 hours.

[0079] The preparation method of the intermediate layer film of the composite antibacterial water-absorbing pad loaded with thirteen spices essential oil has the following differences compared with the preparation method of the inner layer film:

[0080] Step (1) becomes: stirring an aqueous solution containing PG, ZN and TSEO at a speed of 100 to 200 r / min and a temperature of 25 to 60° C. for 30 to 60 minutes to prepare a membrane-forming solution;

[0081] Step (3) becomes: after degassing for 10 to 30 minutes using ultrasonic waves (40 kHz, 700 W), the film-forming liquid is continuously cast on the surface of the inner film (temperature 25 to 50° C., drying for 4 to 8 hours) to form a film, and the second film product formed on the surface of the inner film is the middle layer film of the peach gum-based multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil.

[0082] The preparation method of the outer layer film of the peach gum-based multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil has the following differences compared with the preparation method of the inner layer film:

[0083] Step (1) becomes: stirring an ethanol aqueous solution containing ZN and TSEO at a speed of 100 to 200 r / min and a temperature of 25 to 35° C. for 30 to 40 minutes to prepare a membrane-forming solution;

[0084] Step (3) becomes: after degassing for 10 to 30 minutes using ultrasonic waves (40 kHz, 700 W), the film-forming liquid is continuously cast on the surface of the intermediate layer membrane (temperature 25 to 50° C., drying for 4 to 8 hours) to form a film, and the third layer of film product formed on the surface of the intermediate layer membrane is the outer layer membrane of the peach gum-based multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil.

[0085] In some embodiments of the present invention, preferably, in step (1) of the outer layer membrane preparation method, the preparation method of the ethanol aqueous solution containing ZN and TSEO is: adding the purchased ZN powder to a pre-prepared ethanol aqueous solution with a volume fraction of 80% (v / v) to prepare a ZN ethanol aqueous solution, wherein the mass ratio of PG powder to the ethanol aqueous solution is (2.5-10):100; mixing TSEO with the aforementioned ZN ethanol aqueous solution to prepare an outer layer membrane liquid, wherein the usage ratio of TSEO to the aforementioned ZN ethanol aqueous solution is (0.5-2.5) mL:100 g.

[0086] The peach gum-based multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil for preserving cold fresh meat provided by the present invention is prepared by the method described in any single-layer film or the method described in any multi-layer film (inner layer, middle layer and outer layer).

[0087] The present invention also provides a method for using a peach gum-based multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil in the preservation of a cold fresh meat tray, comprising the following steps:

[0088] Firstly, the composite antibacterial water-absorbing pad is cut and affixed to the inner side of the cold fresh meat tray packaging material;

[0089] Then store it at 0-10℃.

[0090] The invention also provides use of the composite antibacterial water-absorbing pad for maintaining the freshness of cold fresh meat.

[0091] The invention provides a preparation method and a use method of a composite antibacterial water-absorbing pad. A PG film loaded with TSEO is used as an inner layer, a ZN film loaded with TSEO is used as an outer layer, and a composite film of PG\ZN (1:3, 1:1, 3:1) with high efficiency loading of TSEO is used as an intermediate layer. The prepared multi-layer composite antibacterial water-absorbing pad can maintain the freshness of cold fresh meat during storage, and can achieve the water retention, color protection and antibacterial effects of the cold fresh meat; meanwhile, it has the characteristics of simple process, low cost, green and environmental protection, etc.

[0092] The present invention is achieved by providing a peach gum-based multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil and its application in preserving cold fresh meat. The method of using the peach gum-based multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil to carry out tray packaging of cold fresh meat to maintain the freshness of the cold fresh meat comprises the following steps:

[0093] The preparation steps of the inner layer membrane are as follows: grind the purchased large PG particles into powder, pass through a 100-mesh sieve, and then add water to prepare a 2.5-10% (w / w) PG aqueous solution, wherein the amount of TSEO added is 0.5-2.5% (v / w). Stir the mixed aqueous solution containing PG and TSEO at a speed of 100-200r / min and a temperature of 50-60°C for 40-60 minutes to prepare a membrane-forming liquid. Use a high-speed homogenizer to homogenize the membrane-forming liquid at 8000-10000rpm for 1-5 minutes. After degassing for 10-30 minutes using ultrasound (40kHZ, 700W), the membrane-forming liquid is cast (temperature 25-50°C, drying for 4-8 hours) to form a membrane. The membrane drying method is hot air drying or fume hood drying (place the cast membrane liquid in a fume hood and dry it naturally at room temperature for 4-8 hours). The formed membrane product is the inner membrane of the peach gum-based multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil;

[0094] The preparation steps of the intermediate layer membrane are as follows: grind the purchased large PG particles into powder, pass through a 100-mesh sieve, add water to prepare a 2.5-10% (w / w) PG aqueous solution, add the purchased ZN powder to the pre-prepared 80% (v / v) ethanol aqueous solution to prepare a 2.5-10% (w / w) ZN ethanol aqueous solution, wherein the added amount of TSEO is 0.5-2.5% (v / w).

[0095] The mixed solution containing PG, ZN and TSEO is stirred for 30 to 60 minutes at a speed of 100 to 200 r / min and a temperature of 25 to 60°C to prepare a film-forming liquid. The film-forming liquid is homogenized at 8000 to 10000 rpm by a high-speed homogenizer for 1 to 5 minutes. After degassing by ultrasonic wave (40kHZ, 700W) for 10 to 30 minutes, the film-forming liquid is continuously cast on the surface of the formed inner film (temperature 25 to 50°C, drying for 4 to 8 hours) to form a film. The film drying method is hot air drying or fume hood drying (the film liquid after casting is placed in a fume hood and dried naturally at room temperature for 4 to 8 hours). The second layer of film product formed on the surface of the inner film is the middle layer film of the peach gum-based multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil.

[0096] The steps for preparing the outer layer membrane are as follows: the purchased ZN powder is added to the 80% (v / v) ethanol aqueous solution prepared in advance to prepare a 2.5-10% (w / v) ZN ethanol aqueous solution, wherein the amount of TSEO added is 0.5-2.5% (v / w). The mixed solution containing ZN and TSEO is stirred at a speed of 100-200r / min and a temperature of 25-35°C for 30-40 minutes to prepare a membrane-forming liquid. The membrane-forming liquid is homogenized at 8000-10000rpm by a high-speed homogenizer for 1-5 minutes. After degassing by ultrasonic wave (40kHZ, 700W) for 10-30 minutes, the membrane-forming liquid is continuously cast on the surface of the formed intermediate layer membrane (temperature 25-50°C, drying for 4-8 hours) to form a membrane. The membrane drying method is hot air drying or fume hood drying (the membrane liquid after casting is placed in a fume hood and naturally dried at room temperature for 4-8 hours). The third layer of membrane product formed on the surface of the middle layer of membrane is the outer layer of the peach gum-based multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil.

[0097] The steps for using the multi-layer composite antibacterial absorbent pad are as follows: place the fresh cold meat that has passed the quarantine in a tray-type packaging box, stick the cut absorbent pad to the inside of the tray packaging box, seal the packaging box with a sealing film, and store it at 4°C.

[0098] The present invention provides a method for preparing a composite antibacterial absorbent pad, wherein a PG film loaded with TSEO is used as an inner layer, a ZN film loaded with TSEO is used as an outer layer, and a composite film of different ratios of PG\ZN (1:3, 1:1, 3:1) loaded with TSEO is used as an intermediate layer, to prepare a multi-layer composite antibacterial absorbent pad. The present invention provides a material and a preparation method for a multi-layer composite antibacterial absorbent pad, and the multi-layer composite antibacterial absorbent pad prepared by the present invention replaces the traditional technology for preserving and refrigerating cold fresh meat. At the same time, the materials used in the present invention are all natural plant components, which are safe, non-toxic and biodegradable, and have a wide range of applications, stable performance and low production cost.

[0099] Peach gum (PG) large particles were purchased from Wuhan Songtao Agricultural Science and Technology Development Co., Ltd.;

[0100] Thirteen spices essential oil (TSEO) was purchased from Zhengzhou Xuemailong Food Spice Co., Ltd. (MY7003); the formula of the seasoning "Thirteen spices" was: cardamom, amomum villosum, nutmeg, cinnamon, cloves, prickly ash, star anise, cumin, costus root, angelica dahurica, galangal, dried ginger, and black pepper;

[0101] Zein (ZN) powder was purchased from Merck (Z3625).

[0102] Example 1

[0103] A multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil, comprising an inner layer film, an intermediate layer film and an outer layer film stacked in sequence; wherein:

[0104] The inner membrane includes peach gum (PG) and thirteen spice essential oil (TSEO);

[0105] The middle layer membrane includes peach gum (PG), zein (ZN) and thirteen spice essential oil (TSEO);

[0106] The outer membrane includes zein (ZN) and thuja spicata essential oil (TSEO).

[0107] The preparation method of the multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil comprises the following steps:

[0108] (1) Preparation of membrane-forming solution:

[0109] S1. Preparation of inner membrane liquid: Grind peach gum (PG) large particles into powder, and pass through a 100-mesh sieve to obtain PG powder; Mix 2.5 g PG powder with 100 g water to prepare a 2.5% (w / w) PG aqueous solution; Mix 0.5 mL thirteen spice essential oil (TSEO) with 100 g of the aforementioned 2.5% (w / w) PG aqueous solution (stir for 60 minutes at a speed of 150 r / min and a temperature of 60° C.) to prepare an inner membrane liquid (a mixed aqueous solution containing PG and TSEO);

[0110] S2, preparing the intermediate layer membrane liquid: grind the large particles of peach gum (PG) into powder, and pass it through a 100-mesh sieve to obtain PG powder; mix 2.5g PG powder with 100g water to prepare a 2.5% (w / w) PG aqueous solution; mix 7.5g zein (ZN) powder with 100mL of 80% ethanol aqueous solution by volume to prepare a 7.5% (w / v) ZN ethanol aqueous solution; mix the aforementioned 2.5% (w / w) PG aqueous solution and the aforementioned 7.5% (w / v) ZN ethanol aqueous solution in a volume ratio of 1:1 to obtain a mixed solution containing PG and ZN; mix 1mL of thirteen spices essential oil (TSEO) with 100g of the aforementioned mixed solution containing PG and ZN (stir for 30 minutes at a speed of 150r / min and a temperature of 40°C) to prepare an intermediate layer membrane liquid (a mixed solution containing PG, ZN and TSEO);

[0111] S3, preparing outer membrane solution:

[0112] 7.5 g of zein (ZN) powder and 100 mL of 80% ethanol aqueous solution were mixed to prepare a 7.5% (w / v) ZN ethanol aqueous solution; 1 mL of thirteen spices essential oil (TSEO) was mixed with 100 g of the aforementioned 7.5% (w / v) ZN ethanol aqueous solution (stirred for 30 minutes at a speed of 150 r / min and a temperature of 25° C.) to prepare an outer membrane liquid (a mixed solution containing ZN and TSEO);

[0113] (2) Preparation of water-absorbing pad:

[0114] The film-forming liquid (inner film liquid, middle film liquid and outer film liquid) was homogenized (using a high-speed homogenizer to homogenize the film-forming liquid at 9000 rpm for 2 minutes) and degassed (ultrasonic degassed at 40 kHz and 700 W for 30 minutes), and then cast layer by layer according to the set order to form a multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil (denoted as Z-ZP 3:1 -P), the inner film, the middle film and the outer film of the absorbent pad are stacked in sequence; wherein the inner film is prepared from the inner film liquid, the middle film is prepared from the middle film liquid, and the outer film is prepared from the outer film liquid.

[0115] Specifically, the layer-by-layer casting includes the following steps: first, the inner layer film liquid is cast into a film in a fume hood (temperature 25°C, ventilation and drying for 6 hours) to obtain the inner layer film; the middle layer film liquid is continuously cast into a film on the surface of the formed inner layer film (temperature 25°C, ventilation and drying for 6 hours), and the second film formed on the surface of the inner layer film is the middle layer film; the outer layer film liquid is continuously cast into a film on the surface of the formed middle layer film (temperature 25°C, ventilation and drying for 6 hours), and the third film formed on the surface of the middle layer film is the outer layer film. Among them, all the film-forming liquids (inner layer film liquid, middle layer film liquid and outer layer film liquid) are spread on a disc culture dish with a diameter of 90 mm.

[0116] Example 2

[0117] A multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil (denoted as Z-ZP 1:1 -P) and its preparation method, refer to Example 1, the difference is only that:

[0118] When preparing the inner membrane solution, the ratio of PG powder to water was changed to obtain a 5% (w / w) PG aqueous solution, and the inner membrane solution was further prepared based on this;

[0119] When preparing the outer membrane solution, the ratio of ZN powder to ethanol aqueous solution is changed to obtain a 5% (w / v) ZN ethanol aqueous solution, and the outer membrane solution is further prepared based on the 5% (w / v) ZN ethanol aqueous solution;

[0120] When preparing the intermediate layer membrane liquid, the ratio of PG powder to water was changed to obtain a 5% (w / w) PG aqueous solution, and the ratio of ZN powder to ethanol aqueous solution was changed to obtain a 5% (w / v) ZN ethanol aqueous solution, and the intermediate layer membrane liquid was further prepared based on this.

[0121] Example 3

[0122] A multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil (denoted as Z-ZP 1:3 -P) and its preparation method, refer to Example 1, the difference is only that:

[0123] When preparing the inner membrane solution, the ratio of PG powder to water was changed to obtain a 7.5% (w / w) PG aqueous solution, and the inner membrane solution was further prepared based on this;

[0124] When preparing the outer membrane solution, the ratio of ZN powder to ethanol aqueous solution was changed to obtain 2.5% (w / v) ZN ethanol aqueous solution, and the outer membrane solution was further prepared based on the 2.5% (w / v) ZN ethanol aqueous solution;

[0125] When preparing the intermediate layer membrane liquid, the ratio of PG powder to water was changed to obtain a 7.5% (w / w) PG aqueous solution, and the ratio of ZN powder to ethanol aqueous solution was changed to obtain a 2.5% (w / v) ZN ethanol aqueous solution, and the intermediate layer membrane liquid was further prepared based on this.

[0126] Comparative Example 1

[0127] A method for preparing a PG single-layer antibacterial water-absorbing pad (denoted as P) loaded with thirteen spices essential oil comprises the following steps:

[0128] Grind large peach gum (PG) particles into powder, and pass through a 100-mesh sieve to obtain PG powder; mix 10 g of PG powder with 100 g of water to prepare a 10% (w / w) PG aqueous solution; mix 2.5 mL of thirteen-spice essential oil (TSEO) with 100 g of the aforementioned 10% (w / w) PG aqueous solution (stir for 60 minutes at a speed of 150 r / min and a temperature of 60° C.) to prepare a film-forming solution (a mixed aqueous solution containing PG and TSEO);

[0129] The film-forming liquid was homogenized at 9000 rpm for 2 minutes using a high-speed homogenizer; ultrasonic (40 kHz, 700 W) was used for degassing for 30 minutes, and the film-forming liquid was cast into a film in a fume hood (temperature 25°C, ventilation and drying for 6 hours), which was a PG single-layer antibacterial absorbent pad.

[0130] Comparative Example 2

[0131] A method for preparing a ZN single-layer antibacterial water-absorbing pad (denoted as Z) loaded with thirteen spices essential oil comprises the following steps:

[0132] 10 g of zein (ZN) powder and 100 mL of 80% ethanol aqueous solution were mixed to prepare a 10% (w / v) ZN ethanol aqueous solution; 2.5 mL of tsubaki essential oil (TSEO) and 100 g of the aforementioned 10% (w / v) ZN ethanol aqueous solution were mixed (stirred for 30 minutes at a speed of 150 r / min and a temperature of 25° C.) to prepare a film-forming liquid (a mixed solution containing ZN and TSEO); the film-forming liquid was homogenized at 9000 rpm for 2 minutes using a high-speed homogenizer; ultrasonic degassing (40 kHz, 700 W) was used for 30 minutes, and the film-forming liquid was cast into a film in a fume hood (temperature 25° C., ventilation and drying for 6 hours), namely, a ZN single-layer antibacterial absorbent pad.

[0133] A. The antibacterial absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were characterized and compared in terms of chemistry, microstructure and appearance. The results are as follows:

[0134] Figure 2 It is a comparison diagram of infrared spectra of the antibacterial water-absorbing pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2;

[0135] Figure 3 It is a comparison diagram of the X-ray diffraction patterns of the antibacterial absorbent pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2;

[0136] Figure 4 It is a comparison diagram of the thermodynamic spectra of the antibacterial absorbent pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2;

[0137] Figure 5 The following is a comparison of the appearance of the antibacterial absorbent pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2;

[0138] Figure 6 The microstructure diagrams of the surfaces and cross sections of the antibacterial absorbent pads of Examples 1 to 3 of the present invention and Comparative Examples 1 to 2 are compared;

[0139] Experimental studies have found that Figures 2 to 6As shown, compared with comparative examples 1 to 2, the antibacterial absorbent pads (TSEO-ZN / PG composite multilayer films) of embodiments 1 to 3 of the present invention present a heterogeneous structure. It can be seen from comparative examples 1 to 3 that the reduction of the ZN / PG dosage ratio in the intermediate layer film can alleviate this heterogeneous structure, weaken the hydrophobic interaction between non-polar molecules, and form a more ordered PG network structure, thereby enhancing the intermolecular force, increasing the degree of molecular aggregation, and being more conducive to improving the compactness of the film. When the ZN / PG dosage ratio is 1:3 (Example 3), a relatively stable crystal structure can be formed, and an antibacterial absorbent pad product with excellent comprehensive properties such as thermal stability and compactness can be obtained, which is more conducive to practical application. Among them, the thermal stability of the antibacterial absorbent pad characterizes the thermal decomposition structural stability of the film when high temperature fluctuations are encountered during the transportation and storage of meat products. The better the thermal stability of the antibacterial absorbent pad, the more it can ensure the integrity of the membrane structure; even after absorbing water, it can be stably formed and not decomposed, which is more conducive to the stable diffusion and sustained release of the essential oil bound inside.

[0140] B. The transmittance and opacity values ​​of the antibacterial absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were measured by using an ultraviolet spectrophotometer within a wavelength range of 200 to 800 nm. The opacity value was calculated using the following formula:

[0141]

[0142] T 600 is the transmittance at 600 nm, and X is the thickness of the absorption pad (mm).

[0143] Table 1 Transmittance and opacity value measurement results

[0144]

[0145] C. The antibacterial absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to colorimetric measurement. The L* (brightness), a* (redness) and b* (yellowness) of the absorbent pads were measured by a random five-point measurement method using an automatic handheld colorimeter (CR-400 Konica Minolta Technology Co., Ltd.). ΔE and whiteness index (WI) were calculated according to the following formula:

[0146]

[0147] Table 2 Measurement results of L*, a*, b*, ΔE and WI values ​​of water-absorbing pad

[0148]

[0149] D. The thickness and mechanical strength of the antibacterial absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were measured. The thickness of the absorbent pads was measured by a thickness gauge (randomly selecting 5 positions for measurement); the elongation at break (EAB), Young's modulus (YM) and tensile strength (TS) of the absorbent pads were measured by a universal material testing machine. The absorbent pads were cut into dumbbell shapes (35 mm × 2 mm), installed in a stretching fixture with an initial distance of 25 mm, and then stretched on a 0.1 N weighing sensor at a speed of 5 mm / min until they broke. Each sample was tested at least 3 times, and the average value was recorded and calculated.

[0150] Table 3 Measurement results of water-absorbing pad thickness and mechanical strength

[0151]

[0152] Compared with the ZN single-layer antibacterial absorbent pad (Z) loaded with thirteen spices essential oil in comparative example 2, the multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil prepared in Examples 1 to 3 of the present invention improves the light transmittance and reduces the opacity value of the absorbent pad through the design of the multi-layer structure and the compounding of peach gum, giving consumers a better visual experience; at the same time, the elongation at break (EAB), Young's modulus (YM) and tensile strength (TS) of the absorbent pad are improved, the mechanical properties of the absorbent pad are improved, and it is more conducive to the application in the preservation of fresh meat, as shown in Tables 1 to 3, Figure 1 and Figure 5 shown.

[0153] The ZN single-layer antibacterial absorbent pad (Z) loaded with thirteen spices essential oil in comparative examples 1 to 3 differs only in that the ratio of PG\ZN in the middle layer film is different. The study found that as the ratio of PG\ZN in the middle layer gradually increases, the EAB and TS of the composite film gradually increase. This is because PG itself can form a stable gel network structure, and the interaction with ZN enhances the density of its network structure, and has stronger flexibility and ductility, which is different from the ZN single-layer antibacterial absorbent pad (Z) loaded with thirteen spices essential oil in comparative example 2, which has rigidity (lower YM).

[0154] E. The antibacterial absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to water contact angle (WCA) and water vapor transmission rate (WVP) measurements:

[0155] WCA: Drop 2 μL of distilled water onto the Z or P side of the absorbent pad and use a digital camera to take images of the water drop at 0 and 60 seconds. Each sample is tested at least 3 times, and then the average value is recorded and calculated.

[0156] WVP: Fix the absorbent pad (cut into small discs) on the top of a 10mL tube (1.5cm diameter) filled with 6mL of deionized water. Expose the Z side or P side of the absorbent pad to water vapor to measure the WVP on both sides. Place the test tube in a sealed fresh-keeping box filled with desiccant and leave it at room temperature for 3 days. Test once every 12 hours and test each sample 3 times. Calculate WVP according to the following formula:

[0157]

[0158] Where W s is the weight loss of the test tube (g); L is the thickness of the absorbent pad (m); A t is the exposed area (m2) of the absorbent pad at different test times (gain time t) 2 ) ;.ΔP is the vapor pressure difference between the upper and lower surfaces of the absorbent pad (2915.5 Pa at 25°C).

[0159] Table 4 Measurement results of water absorbent pad WCA and WVP

[0160]

[0161]

[0162] As shown in Table 4, the WCA of the PG monolayer antibacterial water absorbent pad (P) loaded with thirteen spices essential oil in Comparative Example 1 at 0 seconds and 60 seconds is greater than that of the ZN monolayer antibacterial water absorbent pad (Z) loaded with thirteen spices essential oil in Comparative Example 2. Figure 6 From the scanning electron microscope (SEM) results, it can be seen that the Z side of the Z film of comparative example 2 or the multilayer film of examples 1 to 3 presents a porous structure, thereby increasing the surface wettability of the film and reducing the contact angle value, while the P film of comparative example 1 or the P side of the multilayer film of examples 1 to 3 presents a tighter surface, thereby enhancing the water resistance of the film surface. This may explain why the contact angle value of the zein side of the Z film or multilayer film made of hydrophobic material is lower than expected. This also shows that the water absorption performance of the water absorbent pad is jointly determined by multiple factors such as material composition and structure.

[0163] It can be seen from Table 4 that compared with the PG monolayer antibacterial absorbent pad (P) loaded with thirteen spices essential oil in comparative example 1 and the ZN monolayer antibacterial absorbent pad (Z) loaded with thirteen spices essential oil in comparative example 2, the multilayer composite antibacterial absorbent pad loaded with thirteen spices essential oil in Examples 1 to 3, through the design of the multilayer structure and the compounding of peach gum, significantly reduces the water vapor permeability (WVP) on both sides of the P side and the Z side, which is beneficial to maintain the appropriate humidity of the fresh meat and achieve better preservation; in addition, the water absorption performance of the absorbent pad is also changed. The WCAt=60s from the Z side to the P side of Examples 1 to 3 is significantly increased compared with the Z film of Comparative Example 2, indicating that the water resistance of the absorbent pad from the Z side to the P side is improved, and the WCAt=60s from the P side to the Z side of Examples 1 to 3 is significantly reduced compared with the P film of Comparative Example 1, indicating that the water absorption of the absorbent pad from the P side to the Z side is improved.

[0164] F. The water swelling degree, water solubility and volatility mass fraction of the water-absorbing pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were measured:

[0165] The dried sample (W1) was immersed and sealed in a beaker containing 30 mL of deionized water at 37°C and 200 rpm for 5 hours with constant magnetic stirring. Then, the swollen sample was weighed after removing the surface moisture (W2), and the swelling degree was calculated as follows:

[0166]

[0167] The swollen sample was dried at 50°C for 24 hours and weighed again (W3). The water solubility calculation formula is as follows:

[0168]

[0169] Accurately weigh the absorbent pad (W a ), and dried in an oven at 105°C for 24 hours. Record the mass of the absorbent sheet after drying (W b ). The volatile mass fraction calculation formula is as follows:

[0170]

[0171] G. Determine the retention rate of TSEO of the absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2. Disperse the absorbent pad (1 g) in 30 mL of 80% (v / v) ethanol solution and stir magnetically (600 rpm) until completely dissolved. Take 1 mL of the supernatant and dilute it 4 times with n-hexane, and measure the absorbance at 260 nm using a spectrophotometer (UV-1800, Shimadzu, Japan). Determine the amount of TSEO (M0) based on the absorbance standard curve of TSEO, and calculate the retention rate of TSEO in the absorbent pad, the formula is as follows:

[0172]

[0173] Where M is the initial content of TSEO in 1g of the absorbent pad.

[0174] H. Determine the release rate of TSEO in 80% glycerol (aqueous food simulant) in the absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2;

[0175] Soak the absorbent pad (1 g) in 30 mL of glycerol (80% v / v) and stir magnetically at 600 rpm. Take 0.5 mL of sample solution and dilute it with 3 mL of n-hexane every 12 hours. Measure the absorbance at 260 nm using a UV-1800 spectrophotometer. At the same time, add blank solvent (0.5 mL) to the water-containing food simulant in time. Calculate the TSEO release rate based on the absorbance standard curve, as follows:

[0176]

[0177] Among them, M t is the TSEO content measured by th, and M is the TSEO content initially loaded in 1 g of the absorbent pad.

[0178] I. The release rate of TSEO in the absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2 in n-hexane (oil-containing food simulant) was measured;

[0179] Soak the absorbent pad (1g) in 30mL of n-hexane and stir magnetically at 600rpm. Take 0.5mL of sample solution and dilute it with 3mL of n-hexane every 12h. Measure the absorbance value at 260nm with a UV-1800 spectrophotometer. At the same time, add blank solvent (0.5mL) to the oil-containing food simulant in time. Calculate the TSEO release rate according to the absorbance standard curve, the formula is as follows:

[0180]

[0181] Among them, M t is the TSEO content measured by th, and M is the TSEO content initially loaded in 1 g of the absorbent pad.

[0182] J. The antibacterial activity of the absorbent pads prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was tested: the antibacterial activity of the absorbent pads against Staphylococcus aureus and Escherichia coli was determined by the inhibition zone method. The bacterial suspension (100 μL, 10 6CFU / mL) was inoculated on solid agar medium. The membrane sample was cut into 6 mm diameter discs and attached to a culture dish inoculated with bacteria, and then the culture dish was incubated at 37°C for 24 hours. Filter paper discs containing saline and solvent were used as negative controls. The antibacterial activity of the sample to be tested was determined by measuring the average diameter of the inhibition zone (mean ± standard deviation).

[0183] Figure 7 The results of water swelling, water solubility and volatility mass fraction of the water absorbent pads in Examples 1 to 3 and Comparative Examples 1 to 2 are as follows;

[0184] Figure 8 is the retention rate of TSEO of the absorbent pads in Examples 1 to 3 and Comparative Examples 1 to 2;

[0185] Fig. 9 is the release rate of TSEO of the absorbent pad in Examples 1 to 3 and Comparative Examples 1 to 2 in 80% glycerol (aqueous food simulant);

[0186] Fig.10 is the release rate of TSEO of the absorbent pad in Examples 1 to 3 and Comparative Examples 1 to 2 in n-hexane (oil-containing food simulant);

[0187] Fig.11 The antibacterial test results of the absorbent pads in Examples 1 to 3 and Comparative Examples 1 to 2 are shown;

[0188] The results show that compared with the single-layer absorbent pads of comparative examples 1 to 2, the antibacterial absorbent pads (TSEO-ZN / PG composite multilayer films) of embodiments 1 to 3 of the present invention can significantly improve the water solubility, swelling degree and volatile mass fraction of ZN, significantly increase the retention rate of TSEO of PG, and achieve better TSEO release performance, thereby greatly improving the utilization rate of thirteen spices essential oil (TSEO) in the absorbent pad, thereby reducing production costs. Among them, Z-ZP 1:3 -P has a higher TSEO release level in oil-containing food simulant (n-hexane), indicating that its responsiveness and controllable release to oil-containing food (fatty food) are better than other composite multilayer films; Z-ZP 3:1 -P has a high level of TSEO release in aqueous food simulants (80% glycerol), indicating that its responsiveness and controllable release to aqueous foods are better than other composite multilayer films. Through antibacterial tests, it is confirmed that the TSEO-ZN / PG composite multilayer films of Examples 1 to 3 of the present invention have a significant inhibitory effect on the growth and development of Staphylococcus aureus and Escherichia coli, and a composite multilayer film product with excellent release performance, antibacterial properties and other excellent properties is obtained. Therefore, the antibacterial absorbent pads (TSEO-ZN / PG composite multilayer films) of Examples 1 to 3 of the present invention can be used in the preservation of fresh cold meat.

[0189] Comparative Example 3

[0190] A multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil and a preparation method thereof are obtained by modifying the optimal preparation method of the literature "Chen Xia. Construction and activity regulation of zein / gelatin edible film [D]. Guangdong: South China University of Technology, 2020.", using Z-ZG 1:2 -G multilayer membrane system, the load is replaced with thirteen spices essential oil. Specifically, the preparation method of the multilayer structure composite antibacterial water-absorbing pad loaded with thirteen spices essential oil is as follows:

[0191] (1) Preparation of hydrophobic outer layer Zein stock solution (Z): 15% (w / w) Zein was dissolved in 100% acetic acid solution and stirred for 2 h under magnetic stirring; 26% (v / w) glycerol was added and the mixture was mixed for 15 min under magnetic stirring;

[0192] (2) Intermediate layer TSEO-Zein / Gelatin stock solution (TSEO / ZG 1:2 ) preparation: Zein and Gelatin were prepared according to ZG 1:2 The mixture was dissolved in 80% acetic acid-water solution with a ratio of 5% (Zein: 5% w / v; Gelatin: 10% w / v) and stirred for 2 h under magnetic stirring. 26% (v / w) glycerol was added and mixed for 15 min under magnetic stirring. Then TSEO was slowly added drop by drop to the ZG 1:2 The mass ratio of TSEO in the stock solution (continuous stirring state) is 7.5% (w / w), and stirring is continued for 30 min;

[0193] (3) Preparation of hydrophilic inner layer TSEO / Gelatin stock solution (TSEO / G): Dissolve 10% (w / w) Gelatin in distilled water at 45-50°C and stir for 2 h under magnetic stirring; add 13% (v / w) glycerol and continue to mix under magnetic stirring for 15 min, then slowly add TSEO solution drop by drop into the above G stock solution (keep stirring, temperature 45-50°C, ensure that the G stock solution is in solution state), the mass ratio of TSEO is 2.5% (w / w), and continue stirring for 30 min;

[0194] The above-mentioned stock solutions were ultrasonically degassed for 10-15 minutes, and 2 mL of the above-mentioned Z stock solution, TSEO / ZG 1:2 stock solution, and TSEO / G stock solution were cast into films in turn; the interval between the film formation of each two layers was 3-4 hours, that is, the next layer of film was cast after the previous layer of film was partially dehydrated to the extent of surface dryness, to obtain Z-TSEO / ZG 1:2-TSEO / G multi-layer functional film. The peeled film is stored in a dryer at a temperature of 25-30°C and an ambient humidity of 52-53%.

[0195] Experimental studies have found that, according to the method in the literature, after the load is replaced with TSEO, the hydrophilic inner layer TSEO / G reserve solution is thick when cast into a film and cannot be cast into a film (e.g. Fig.16 As shown), it is ultimately impossible to prepare Z-TSEO / ZG loaded with thirteen spices essential oil. 1:2 -TSEO / G multilayer functional film. In addition, the middle layer TSEO-Zein / Gelatin stock solution (TSEO / ZG 1:2 ) and the hydrophobic outer layer Zein stock solution (Z) produced uneven distribution of membranes (e.g. Fig.17 and Fig.18 As shown), the mechanical strength is low and it is difficult to use as a water absorbent pad; the film prepared in Comparative Example 3 is accompanied by a strong pungent smell of acetic acid after drying. When it is used to preserve fresh pork, it will affect the smell experience of fresh pork and is not conducive to consumers' acceptance of its use.

[0196] Comparative Example 4

[0197] A multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil and a preparation method thereof, referring to Example 3 (Z-ZP 1:3 -P), the only difference is that peach gum (PG) is replaced by other commonly used natural hydrophilic (water-absorbing) materials, such as soluble starch, sodium alginate, pullulan or gelatin.

[0198] Experimental studies have found that when peach gum (PG) is replaced with other commonly used natural hydrophilic (water-absorbing) materials, it is impossible to produce a uniform and relatively stable film-forming liquid, and thus it is impossible to successfully prepare a multi-layered composite antibacterial absorbent pad loaded with thirteen spices essential oil. Specifically, when peach gum (PG) is replaced with soluble starch, the middle layer of the film-forming liquid generates precipitation and stratification occurs (such as Fig.19 When peach gum (PG) is replaced by sodium alginate, pullulan or gelatin, the intermediate film-forming liquid has solidified into blocks before layer-by-layer casting (as shown in Fig. 20 , Fig.21 and Fig. 22 As shown). It can be seen that the selection of natural hydrophilic (water-absorbing) materials is crucial for the successful preparation of the multi-layered composite antibacterial absorbent pad loaded with thirteen spices essential oil. After peach gum is replaced with the above several commonly used natural hydrophilic (water-absorbing) materials, the absorbent pad cannot be prepared.

[0199] Example 4

[0200] A method for using a multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil in the storage process of fresh pork, wherein the multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil is prepared by the method described in Example 1.

[0201] The method for using a multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil during the storage of fresh pork comprises the following steps: sticking a 3 cm×3 cm absorbent pad on the inner wall of a pallet packaging box, placing 50 g of fresh pork that has passed quarantine on the multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil in the pallet, sealing the packaging box with a sealing film, and storing it at 4°C.

[0202] Example 5

[0203] A method for using a multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil in the storage process of fresh pork is disclosed, with reference to Example 4, except that the multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil is made by the method described in Example 2.

[0204] Example 6

[0205] A method for using a multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil in the storage process of fresh pork is described with reference to Example 4, except that the multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil is made by the method described in Example 3.

[0206] Comparative Example 5

[0207] A method for using a multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil in the storage process of fresh pork is described with reference to Example 4, except that the multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil is prepared by the method described in Comparative Example 1.

[0208] Comparative Example 6

[0209] A method for using a multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil in the storage process of fresh pork is described with reference to Example 4, except that the multi-layer composite antibacterial absorbent pad loaded with thirteen spices essential oil is prepared by the method described in Comparative Example 2.

[0210] Comparative Example 7 (blank)

[0211] Storing fresh meat without any processing.

[0212] Comparative Example 8 (wood fiber paper)

[0213] The invention discloses a method for using traditional wood fiber paper in the process of storing cold fresh pork.

[0214] The preservation effect of fresh pork stored for 10 days in Examples 4 to 6 and Comparative Examples 5 to 8 is compared.

[0215] L. Determination of color

[0216] An automatic handheld colorimeter (CR-400 Konica Minolta Technology Co., Ltd.) was used to read the L* (brightness), a* (redness), and b* (yellowness) of the fresh pork stored for 10 days in Examples 4 to 6 and Comparative Examples 5 to 6, and a white plate was used as a reference.

[0217] M. Determination of pH value

[0218] The minced pork (15 g) was homogenized in 15 mL of distilled water (8000 r / min, 1 minute) and allowed to stand at room temperature for 30 minutes. The mixture was then filtered and the pH of the filtrate was measured using a pH meter.

[0219] N. Determination of total colony count

[0220] 5 g of minced pork was placed in 45 mL of sterile saline and gently homogenized for 20 minutes under sterile conditions. After gradient dilution of the supernatant, plate counts were performed using inoculated plate count agar at 37°C for 48 hours.

[0221] Examples 4 to 6 of the present invention and comparative examples 5 to 8 provide a method for using a composite antibacterial absorbent pad loaded with thirteen spices essential oil in the storage process of cold fresh pork. According to GB / T 9959.2-2008 "National Food Safety Standard: Cut Fresh and Frozen Pork Lean Meat", the total bacterial count (TVC) of cold fresh meat shall not be higher than 6log CFU / g, and the pH is between 5.8 and 6.2 for fresh meat, between 6.3 and 6.6 for sub-fresh meat, and above 6.7 for spoiled meat.

[0222] Fig.12 The TVC results of fresh pork using the absorbent pad of the present invention at different storage periods;

[0223] Fig.13 The pH results of fresh pork at different storage periods using the absorbent pad of the present invention are shown;

[0224] Fig.14 The surface morphology of fresh pork using the water-absorbing pad of the present invention during different storage periods;

[0225] Fig.15 The bottom morphology of fresh pork using the absorbent pad of the present invention at different storage periods.

[0226] The results show that the composite antibacterial absorbent pad loaded with thirteen spices essential oil provided in Examples 1, 2, and 3 can absorb the exudate of fresh meat, have a good effect in inhibiting the corruption of fresh pork, and can more effectively reduce the number of viable bacteria and the total colony count, delay the change in pH value, and delay the browning of fresh pork, thereby extending the shelf life of fresh meat. Its preservation effect is better than that of wood fiber paper, the PG single-layer antibacterial absorbent pad (P) loaded with thirteen spices essential oil in comparative example 1, and the ZN single-layer antibacterial absorbent pad (Z) loaded with thirteen spices essential oil in comparative example 2.

[0227] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

[0228] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil, characterized in that: It comprises an inner film, an intermediate film and an outer film which are stacked in sequence; wherein: The inner membrane includes peach gum and thirteen-spice essential oil; The middle membrane includes peach gum, zein and thirteen-spice essential oil; The outer membrane includes zein and zein essential oil.

2. The multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil according to claim 1, characterized in that: The solvent used in the inner layer film is water; The solvent used for the intermediate layer film and the outer layer film is ethanol aqueous solution.

3. A method for preparing a multi-layer composite antibacterial water-absorbing pad loaded with thirteen spices essential oil, characterized in that: The steps include: (1) Preparation of membrane-forming solution: S01, mixing peach gum powder and water in a mass ratio of (2.5-10):100 to prepare a peach gum aqueous solution; S02, mixing zein powder and ethanol aqueous solution at a ratio of (2.5-10) g:100 mL to prepare zein ethanol aqueous solution; S1, preparing inner membrane liquid: mixing thirteen spices essential oil and the peach gum aqueous solution in a ratio of (0.5-2.5) mL:100 g to prepare inner membrane liquid; S2, preparing an intermediate layer membrane liquid: mixing the peach gum aqueous solution and the zein ethanol aqueous solution at a volume ratio of 1:1 to obtain a mixed solution containing peach gum and zein; mixing thirteen spices essential oil with the mixed solution containing peach gum and zein at a ratio of (0.5-2.5) mL:100 g to prepare an intermediate layer membrane liquid; S3, preparing outer membrane solution: The thirteen spices essential oil and the zein ethanol aqueous solution are mixed at a ratio of (0.5-2.5) mL:100 g to prepare an outer membrane liquid; (2) Preparing a water-absorbing pad: homogenizing and degassing the inner layer membrane liquid, the middle layer membrane liquid and the outer layer membrane liquid, and then casting them layer by layer. The multilayer membrane product formed is the multilayer structure composite antibacterial water-absorbing pad loaded with thirteen spices essential oil as claimed in claim 1 or 2.

4. The method according to claim 3, characterized in that The volume fraction of ethanol in the ethanol aqueous solution in step S02 is 60-90%.

5. The method according to claim 3, characterized in that: The particle size of the peach gum powder in step S01 is 80-200 meshes.

6. The method according to claim 3, characterized in that The mixing in any of step S1, step S2 or step S3 is achieved by stirring at a temperature of 25 to 60° C. and a rotation speed of 100 to 200 r / min.

7. The method according to claim 3, characterized in that The homogenization parameters in step (2) are as follows: homogenization at 8000-10000 rpm for 1-5 minutes.

8. The method according to claim 3, characterized in that The degassing in step (2) is performed by ultrasonic degassing, and the degassing parameters are: 40kHz, 700W degassing for 10 to 30 minutes.

9. The method according to claim 3, characterized in that: The method for drying the film after the layer-by-layer casting in step (2) comprises drying at 25 to 50° C. for 4 to 8 hours.

10. Use of the multi-layer composite antibacterial water-absorbent pad loaded with thirteen spices essential oil as claimed in any one of claims 1 or 2 in the packaging of cold fresh meat.

Images