Degradable edible walnut oil fresh-keeping packaging material and preparation method and application thereof

Abstract

The application belongs to the technical field of fresh-keeping packaging materials, and discloses a degradable edible walnut oil fresh-keeping packaging material, wherein the packaging material is prepared by taking gelatin as a base body, taking dialdehyde polysaccharide and coffee leaf extract as additives, and is used for preparing a packaging material for edible oil and fat which can delay easy oxidation and rancidity; the fresh-keeping packaging material for walnut oil oxidation is verified. The degradable edible packaging material for walnut oil fresh-keeping has excellent water vapor, oxygen and ultraviolet blocking properties and excellent antioxidant properties, and has good mechanical properties and heat sealing properties, can effectively prevent oil and fat in the package from overflowing, and reduce the contact opportunities of the oil and fat in the package with air and light, effectively prevent walnut oil from oxidizing and rancidity, and prolong the shelf life of walnut oil. The packaging material has simple preparation method, low cost and no special equipment requirement, and has great application potential in the field of food packaging.

Description

Technical Field

[0001] This invention belongs to the field of food preservation packaging film technology, and more specifically, discloses a biodegradable edible walnut oil preservation packaging material, its preparation method and application. Background Technology

[0002] Walnuts are one of the world's four most famous nuts, and currently walnut production ranks second globally among nut producers. They are widely cultivated worldwide and are also an important woody oilseed tree species in my country. Walnuts are rich in nutrients, and consuming walnuts or walnut-containing foods has been proven beneficial for heart health, cancer prevention, and metabolic disorders due to their antioxidant and anti-inflammatory properties, as well as their ability to maintain healthy metabolism and immune function. Furthermore, walnuts have a high oil content among nuts, with the kernels generally containing over 60% oil. Walnut oil is rich in unsaturated fatty acids, accounting for over 90% of the total oil content, and also contains sterols, vitamin E, flavonoids, and other lipid byproducts. Walnut oil, obtained through pressing or solvent extraction of walnut kernels, is a highly nutritious edible oil that has become increasingly popular with consumers due to growing health awareness, leading to a year-on-year increase in both production and demand.

[0003] However, walnut oil contains not only abundant monounsaturated fatty acids such as oleic acid, but also high levels of polyunsaturated fatty acids such as linoleic acid and linolenic acid. During processing, storage, and sales, it is highly susceptible to oxidative rancidity, leading to flavor deterioration, reduced nutritional value, and even the production of toxic and harmful substances, adversely affecting human health. This impacts the quality and flavor of walnut oil, increases the difficulty of storage, and shortens its shelf life. Therefore, how to delay and reduce walnut oil oxidation has become a key issue in processing and storage.

[0004] Using antioxidant packaging materials to package walnut oil is an effective way to solve the above problems. Chinese patent CN113086397A discloses a packaging method for preventing walnut oil oxidation. The packaging is a UV-resistant stand-up pouch with an antioxidant coating on its inner wall. The pouch consists of an outer layer and an inner layer. The outer layer is a coating made of a mixture of film-forming resin and nano-sized titanium dioxide, and the inner layer is a polyethylene layer. A one-way check valve is installed at the opening of the pouch. This stand-up pouch can effectively extend the shelf life and shelf life of walnut oil. However, the main component of the stand-up pouch in this patent is plastic, which is a petroleum-based packaging material. It is well known that the extensive use of plastics not only exacerbates environmental "white pollution," but also the toxic plasticizers in plastics may migrate into food, posing a safety risk to human health. Therefore, there is an urgent need to develop a biodegradable and safe packaging material for preserving walnut oil. Summary of the Invention

[0005] The primary objective of this invention is to provide a biodegradable and edible walnut oil preservation packaging material.

[0006] The second objective of this invention is to provide a method for preparing packaging materials based on the constituent components of the biodegradable edible walnut oil preservation packaging material.

[0007] A third objective of this invention is to provide applications for the aforementioned biodegradable edible oil preservation packaging materials, particularly for the preservation of walnut oil.

[0008] The above technical objectives are achieved through the following solutions:

[0009] A biodegradable and edible walnut oil preservation packaging material comprises the following components by weight: 2-6 parts gelatin, 0.2-0.6 parts dialdehyde polysaccharide, 0.1-0.3 parts coffee leaf extract, and 0.4-1.2 parts edible plasticizer; wherein the coffee leaf extract is obtained by extracting coffee leaf powder (conventionally purchased) with water.

[0010] Preferably, the edible plasticizer is one or more of glycerin, ethylene glycol, sorbitol, xylitol, and polyethylene glycol.

[0011] Preferably, the dialdehyde polysaccharide is one or more of dialdehyde carboxymethyl cellulose, dialdehyde sodium alginate, dialdehyde starch, dialdehyde chitosan, and dialdehyde guar gum.

[0012] Preferably, the coffee leaf extract is prepared by adding dry coffee leaf powder to boiling water, maintaining a solid-liquid ratio of 1:20~40g / mL, extracting for 15~30min, taking the supernatant, and then drying and pulverizing it.

[0013] Preferably, 5-15g of polysaccharide is added to 200mL of deionized water, followed by 5.35-5.45g of sodium periodate. After stirring evenly at room temperature, the pH is adjusted to 3-5 with acid / base. The reaction time is 5-6 hours. Finally, 3.5mL of ethylene glycol is added to terminate the reaction. The resulting solution is dialyzed in deionized water for 6-8 days using a dialysis bag. The lyophilized solution is then used to obtain dialdehyde polysaccharide.

[0014] The second objective of this invention is to provide a method for preparing the biodegradable edible walnut oil preservation packaging material. This invention employs a conventional flow-forming film-forming process. More specifically, gelatin is first added to water and stirred, then a plasticizer is added and stirred; then dialdehyde polysaccharide and coffee leaf extract are added sequentially to obtain a mixture, stirred, and a film is formed.

[0015] Preferably, the concentration of gelatin in the mixture is 20~60g / mL.

[0016] A third objective of this invention is to provide the application of the aforementioned biodegradable and edible preservation packaging material in the preparation of preservation packaging materials. Further, the preservation packaging material is an edible oil that is easily oxidized and rancid under natural storage conditions. Even further, the edible oil is walnut oil.

[0017] Compared with the prior art, the superior effects of the present invention are mainly reflected in the following aspects:

[0018] (1) The preparation method of the biodegradable edible walnut oil preservation packaging material of the present invention is simple, easy to operate and does not require complicated instruments and equipment. It is a simple, green and environmentally friendly preparation method with mild conditions.

[0019] (2) The walnut oil preservation packaging material prepared by this invention has excellent water vapor, oxygen, and ultraviolet blocking properties and excellent antioxidant properties, as well as good mechanical and heat-sealing properties. It can not only effectively prevent the packaging material from breaking and the walnut oil from spilling, but also effectively slow down the rancidity of oil caused by external environmental factors such as light, oxygen, and water vapor. The added coffee leaf extract has excellent antioxidant properties, which can further effectively prevent the oxidative rancidity of oil and effectively extend the shelf life of walnut oil.

[0020] (3) The walnut oil preservation packaging material prepared by the present invention has good biodegradability and edibility. After use, it can be degraded by composting, soil burial and other methods. It is green, environmentally friendly and pollution-free. It can also be used for convenient packaging of small-sized walnut oil and can be consumed with walnut oil during use. It is non-toxic and harmless. Attached Figure Description

[0021] Figure 1 To simulate the effects of degradable edible packaging materials, PE film, and no-packaging treatment (control) on the peroxide value (POV) of walnut oil under accelerated oxidation processes;

[0022] Figure 2 To simulate the effects of degradable and edible packaging materials, PE film, and no-packaging treatment (control) on the acid value (AV) of walnut oil under accelerated oxidation processes;

[0023] Figure 3 To simulate the effects of degradable and edible packaging materials, PE film, and no-packaging treatment (control) on the malondialdehyde (MDA) content of walnut oil under accelerated oxidation processes;

[0024] Figure 4 The images show packaging pictures of walnut oil made from the preservation packaging materials of Examples 1-3, from left to right: Examples 1 to 3. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Unless otherwise specified in the embodiments of the present invention, preparation shall be carried out under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products that can be purchased commercially.

[0027] Example 1

[0028] (1) Weigh 2g of commercially available gelatin and add it to 100mL of deionized water. Stir at 50℃ for 1h, then add 0.4g of glycerin as a plasticizer and continue stirring for 20min.

[0029] (2) Weigh 0.2g of dialdehyde carboxymethyl cellulose and add it to the gelatin solution containing plasticizer in step (1) above. Continue stirring at 50°C for 20min. The specific preparation method of the dialdehyde carboxymethyl cellulose is to add 10g of polysaccharide (carboxymethyl cellulose) to 200mL of deionized water, then add 5.35g of sodium periodate, stir evenly at room temperature, adjust the pH to 3 with acid / base, react for 6h, and finally add 3.5mL of ethylene glycol to terminate the reaction. Dialyze the solution obtained from the reaction in deionized water for 6 days using a dialysis bag, and freeze-dry the dialyzed solution to obtain the product.

[0030] (3) Weigh 0.1g of coffee leaf extract and add it to the mixture containing plasticizer, gelatin and dialdehyde carboxymethyl cellulose in step (2) above. Stir for 20 minutes at 50°C. Then pour the mixture into a self-made glass plate to form a film and dry it at room temperature to obtain a composite packaging material containing plasticizer, gelatin, dialdehyde carboxymethyl cellulose and coffee leaf extract.

[0031] The specific preparation method of the coffee leaf extract is to add a certain amount of dry coffee leaf powder to boiling water, maintain a solid-liquid ratio of 1:20 g / mL, extract for 15 min, take the supernatant, freeze-dry and grind it to obtain the coffee leaf extract.

[0032] Example 2:

[0033] (1) Weigh 4g of commercially available gelatin and add it to 100mL of deionized water. Stir at 50℃ for 1.5h, then add 0.8g of ethylene glycol as a plasticizer and continue stirring for 30min.

[0034] (2) Weigh 0.4g of sodium dialdehyde aldehyde and add it to the gelatin solution containing plasticizer in step (1) above, and continue stirring at 50°C for 30min.

[0035] The specific preparation method of the dialdehyde sodium alginate is as follows: 5g of polysaccharide (sodium alginate) is added to 200mL of deionized water, then 5.35g of sodium periodate is added. After stirring evenly at room temperature, the pH is adjusted to 3 with acid / base. The reaction time is 6h, and finally 3.5mL of ethylene glycol is added to terminate the reaction. The resulting solution is dialyzed in deionized water for 7 days using a dialysis bag. The dialyzed solution is then freeze-dried to obtain the final product.

[0036] (3) Weigh 0.2g of coffee leaf extract and add it to the mixture containing plasticizer, gelatin and sodium dialdehyde alkanoate in step (2) above. Stir for 30 minutes at 50°C. Then pour the mixture into a self-made glass plate to form a film and dry it at room temperature to obtain a composite packaging material containing plasticizer, gelatin, sodium dialdehyde alkanoate and coffee leaf extract.

[0037] The specific preparation method of the coffee leaf extract is to add a certain amount of dry coffee leaf powder to boiling water, maintain a solid-liquid ratio of 1:30 g / mL, extract for 20 min, take the supernatant, freeze-dry and grind it to obtain the coffee leaf extract.

[0038] Example 3:

[0039] (1) Weigh 6g of commercially available gelatin and add it to 100mL of deionized water. Stir at 50℃ for 2h, then add 1.2g of sorbitol as a plasticizer and continue stirring for 40min.

[0040] (2) Weigh 0.6g of dialdehyde starch and add it to the gelatin solution containing plasticizer in step (1) above, and continue stirring at 50°C for 20min;

[0041] The specific preparation method of the dialdehyde starch is as follows: 15g of polysaccharide (starch) is added to 200mL of deionized water, then 5.45g of sodium periodate is added. After stirring evenly at room temperature, the pH is adjusted to 3.5 with acid / base. The reaction time is 5.5h. Finally, 3.5mL of ethylene glycol is added to terminate the reaction. The resulting solution is dialyzed in deionized water for 8 days using a dialysis bag. The dialyzed solution is then freeze-dried to obtain the starch.

[0042] (3) Weigh 0.3g of coffee leaf extract and add it to the mixture containing plasticizer, gelatin and dialdehyde starch in step (2) above. Stir for 30 minutes at 50°C. Then pour the mixture into a self-made glass plate to form a film and dry it at room temperature to obtain a composite packaging material containing plasticizer, gelatin, dialdehyde starch and coffee leaf extract.

[0043] The specific preparation method of the coffee leaf extract is to add a certain amount of dry coffee leaf powder to boiling water, maintain a solid-liquid ratio of 1:40 g / mL, extract for 30 min, take the supernatant, freeze-dry and grind it to obtain the coffee leaf extract.

[0044] Application Example 1: Performance Testing of the Biodegradable and Edible Packaging Material Prepared in the Above Examples

[0045] The water vapor transmission rate, oxygen transmission rate, ultraviolet light transmittance, antioxidant properties, and mechanical properties of the biodegradable edible packaging materials prepared in Examples 1-3 were tested. Water vapor transmission rate was tested according to the method in GB1037-1988; oxygen transmission rate was tested according to the method in GB / T19789-2005; ultraviolet light transmittance was measured using an ultraviolet-visible spectrophotometer; antioxidant properties were measured using IC50 and ABTS and DPPH free radical scavenging assays. 50 The values ​​were used for characterization; tensile strength was tested according to the method in GB13022-91, and heat seal strength was tested according to the method in QB / T2358-1998. The results are shown in Tables 1 to 3.

[0046] Table 1. Water vapor transmission rate, oxygen transmission rate, and ultraviolet light transmission rate of the product.

[0047]

[0048] Table 2 Antioxidant Activity of Products

[0049]

[0050] As can be seen from Tables 1-2 above, the biodegradable edible packaging material prepared by the method of the present invention has good water vapor, oxygen and ultraviolet light blocking properties, and excellent antioxidant activity.

[0051] Table 3 Product Mechanical Properties and Heat Sealability

[0052]

[0053] As can be seen from Table 3 above, the biodegradable and edible packaging material prepared by the method of the present invention has good mechanical properties and heat-sealing properties.

[0054] Application Example 2: In order to further verify the preservation effect of composite packaging on walnut oil, the applicant conducted research and exploration experiments on the stability of walnut oil packaged by the present invention, and used unpackaged control and conventional commercially available PE material packaging as a control.

[0055] Specific experiments include:

[0056] (1) Raw material: Walnut oil (from old walnut trees), purchased from Qiaojia County Tuwei Food Co., Ltd., whose label claims that no antioxidants are added.

[0057] (2) Test method:

[0058] The packaging materials prepared in Examples 1-3 were used in a constant temperature chamber at 50℃ to simulate accelerated oxidation of edible oil. 10g of walnut oil was placed in 20mL of the packaging material of this invention. A certain amount of edible oil was taken out at regular intervals of 0, 3, 6, 9, and 12 days. The peroxide value (GB5009.227-2016), acid value (GB5009.229-2016), and malondialdehyde (GB5009.181-2016) were measured. The results were compared with PE film packaging to investigate the effect of the novel composite packaging on the oxidative rancidity of walnut oil.

[0059] (3) Results analysis:

[0060] According to the food safety requirements of the national standard for walnut oil (GB / T22327-2019), the peroxide value (POV) should be ≤0.25g / 100g and the acid value ≤3mg / g (calculated as KOH). The results are shown below. Figure 1 , Figure 2 and Figure 3 .

[0061] Depend on Figure 1 It can be seen that within 0-12 days, the peroxide value of fresh walnut oil treated by different packaging methods fluctuated within a certain range as the oxidation time increased, and the peroxide value of walnut oil generally showed an upward trend with the extension of oxidation time. The oxidation rate of walnut oil in Examples 1-3 was slower than that of other packaging, and the POV value of the blank group was as high as 0.28 g / 100g on day 12, exceeding the requirements of relevant national standards. In contrast, the oxidation rate of walnut oil in Examples 1-3 was slower than that of other packaging, and the POV value of the composite film in Example 3 was the lowest, only 0.07 g / 100g. This is because the composite film in Example 3 has a high barrier to water vapor and oxygen, and the high content of coffee leaf extract in Example 3 provides hydrogen atoms for lipid free radicals or peroxide free radicals and scavenges them, thereby blocking the chain reaction of free radicals and inhibiting the generation of hydrogen peroxide.

[0062] Depend on Figure 2It can be seen that within 0-12 days, the acid value of fresh walnut oil treated by different packaging methods fluctuated within a certain range, and the acid value of walnut oil generally showed an upward trend with the extension of oxidation time. The acid value of the control group on day 12 was 3.71 mg / kg (calculated as KOH), which is greater than 3 mg / g, exceeding the requirements of relevant national standards. In contrast, during the 0-12 day oil oxidation stage, the acid value of walnut oil from Examples 1-3 was lower than that of other packaging methods, and no large amount of free fatty acids were generated. In particular, the acid value of walnut oil preserved by the composite film in Example 3 was only 1.21 mg / kg (calculated as KOH), far less than that of the control group. This indicates that the composite film in Example 3 can effectively slow down the rate of lipid oxidation and inhibit oil degradation.

[0063] Depend on Figure 3 It can be seen that the acid value of fresh walnut oil treated with different packaging methods gradually increased within 0-12 days. However, the malondialdehyde (MDA) content of walnut oil from Examples 1-3 was lower than that of other groups. The MDA content of the blank group reached as high as 3.97 mmol / g on day 12. In contrast, the MDA content of the composite film-preserved walnut oil in Example 3 was the lowest, at only 1.65 mmol / g. This indicates that Example 3 can effectively slow down the rate of lipid oxidation and inhibit the generation of secondary oxidation products. In summary, all the above results show that the packaging of the present invention can effectively maintain the quality of walnut oil and extend its shelf life during storage.

[0064] Figure 4 Examples 1 to 3 demonstrate the packaging of walnut oil using the preservation packaging materials.

[0065] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A biodegradable and edible walnut oil preservation packaging material, characterized in that, It is composed of the following components in parts by weight: 2-6 parts gelatin, 0.2-0.6 parts dialdehyde polysaccharide, 0.1-0.3 parts coffee leaf extract, and 0.4-1.2 parts edible plasticizer; the coffee leaf extract is prepared by adding dry coffee leaf powder to boiling water, maintaining a solid-liquid ratio of 1:20-40 g / mL, extracting for 15-30 min, taking the supernatant, drying and pulverizing it; the dialdehyde polysaccharide is one or more of dialdehyde carboxymethyl cellulose, dialdehyde sodium alginate, and dialdehyde starch.

2. The biodegradable edible walnut oil preservation packaging material according to claim 1, characterized in that, Edible plasticizers are one or more of glycerin, sorbitol, xylitol, and polyethylene glycol.

3. The biodegradable edible walnut oil preservation packaging material according to claim 1, characterized in that, Add 5-15g of polysaccharide to 200 mL of water, then add 5.35-5.45g of sodium periodate. Stir well at room temperature, adjust the pH to 3-5 with acid, and react for 5-6 hours. Finally, add ethylene glycol to terminate the reaction. Dialyze the resulting solution in water for 6-8 days, and freeze-dry the dialyzed solution to obtain dialdehyde polysaccharide.

4. A method for preparing the biodegradable edible walnut oil preservation packaging material according to claim 1, characterized in that, First, add gelatin to water and stir, then add edible plasticizer and stir; then add dialdehyde polysaccharide and coffee leaf extract in sequence to obtain a mixture, stir, and form a film to obtain the final product.

5. The preparation method according to claim 4, characterized in that, The concentration of gelatin in the mixture is 20~60g / mL.

6. The application of the biodegradable edible walnut oil preservation packaging material according to claim 1 in the preparation of preservation packaging products, wherein the preservation packaging products are used to preserve easily oxidized and rancid edible oils under natural conditions, characterized in that... The edible oil is walnut oil.

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