Preparation method of food antibacterial preservative paper based on plant essential oil

Abstract

The invention discloses a preparation method of food antibacterial preservative paper based on plant essential oil, and the preparation method comprises the following steps: S1, firstly selecting beta-cyclodextrin, dissolving the beta-cyclodextrin in water, and stirring and dissolving under the water bath condition of 65-75 DEG C to obtain a beta-cyclodextrin solution; s2, mixing origanum vulgare essential oil with ethanol to obtain a mixed solution A, and then adding the mixed solution A into the beta-cyclodextrin solution in S1; s3, continuously keeping the mixed solution A under a 65-75 DEG C water bath condition, stirring the solution and mixing to obtain a mixed solution B; s4, standing the mixed solution B, and then removing supernatant liquid under a centrifugal condition to obtain a bottom-layer solid; s5, drying the obtained bottom layer solid to obtain the microcapsule; and S6, mixing the microcapsules and PVA to obtain the preservative paper. The fresh-keeping paper not only can prolong the fresh-keeping period of food during long-distance transportation, but also can prolong the shelf life of the food during sales, is easy to degrade, conforms to the green and environment-friendly packaging concept, and provides a thought for food fresh-keeping.

Description

Technical Field

[0001] The invention belongs to the technical field of cling paper preparation, and in particular relates to a method for preparing food antibacterial cling paper based on plant essential oil. Background Art

[0002] At present, polyethylene hydrocarbon plastic film is a commonly used material for food preservation, which prolongs the shelf life of food by isolating oxygen and microorganisms in the air. However, the production and disposal of plastic film will cause environmental pollution and health problems, so it is necessary to find a green and degradable material to replace plastic film. Paper-based materials use plant fibers as the main raw materials, are easy to degrade, and have the advantages of being non-toxic and safe. Using paper-based materials instead of plastic film can effectively solve problems such as environmental pollution. Chemical preservatives are used to inhibit the growth and reproduction of microorganisms in food and are one of the commonly used preservative materials. It achieves the purpose of extending the shelf life of food by adding certain chemicals such as sorbitol, sodium sulfate, borax, etc. to kill bacteria, molds and other microorganisms on the surface of food. However, chemical preservatives may have residual problems, and excessive use may cause health hazards.

[0003] In the Chinese patent application publication number CN 106638156 B, a method for preparing antibacterial fresh-keeping packaging paper is disclosed, which comprises crushing and screening tea husks, selecting tea husk powder, soaking the powder in an antibacterial solution, and then soaking the mixture in water to obtain a tea husk powder mixture; mixing the mixture with waste paper, pulping the mixture, adding a papermaking aid to the pulp, heating and stirring the pulp to obtain paper pulp; replacing expensive paper pulp raw materials with tea husks to save production costs; and utilizing the antibacterial properties of the husks themselves in combination with organic antibacterial agents to improve the antibacterial and fresh-keeping properties of the fresh-keeping paper box. However, the overall preparation cost is relatively high, and although it can also play a certain antibacterial role, its control over the vitamin C content and titratable acid content is limited. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing food antibacterial fresh-keeping paper based on plant essential oils, which solves the above-mentioned technical problems existing in the prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A method for preparing food antibacterial fresh-keeping paper based on plant essential oils comprises the following steps: S1. First, β-cyclodextrin is dissolved in water, and stirred to dissolve in a water bath at 65-75° C. to obtain a β-cyclodextrin solution; S2, mixing oregano essential oil with ethanol to obtain a mixed solution A, and then adding the mixed solution A to the β-cyclodextrin solution of S1; S3, continuously maintaining the mixed solution A in a water bath at 65-75° C. and stirring the solution to obtain a mixed solution B; S4, allowing the mixed solution B to stand, and then removing the supernatant under centrifugal conditions to obtain the bottom solid; S5, drying the obtained bottom solid to obtain microcapsules; S6, after mixing the microcapsules and PVA, the coating amount is 20g / m 3 A proper amount of a mixed solution of microcapsules and PVA is applied to the surface of paper to form a continuous coating layer of the fresh-keeping solution to obtain fresh-keeping paper.

[0006] Furthermore, in S1, the ratio of β-cyclodextrin to water is 12:100.

[0007] Furthermore, in S2, oregano essential oil and ethanol are mixed in a mass ratio of 1:1.

[0008] Furthermore, in S4, the mixed solution B is allowed to stand at a temperature of 3-5°C for 20-24 hours.

[0009] Furthermore, in S2 and S3, the stirring speed is 800 r / min and the time is 2 h.

[0010] In the S4, the centrifugal conditions are a rotation speed of 8000 r / min and a time of 2-3 min.

[0011] Furthermore, in S5, the bottom solid is dried under the following conditions: drying time of 72 h and temperature of -40°C.

[0012] Furthermore, in S6, the mixing ratio of microcapsules and PVA is 1:3.

[0013] Furthermore, in S6, the PVA solution is prepared by adding PVA solid and deionized water at a mass ratio of 1:20, mixing, stirring and dissolving.

[0014] Furthermore, in S6, after coating on the paper, the drying temperature is 60° C. and the drying time is 6 minutes.

[0015] Beneficial effects of the present invention: 1. The present invention uses oregano essential oil, a natural plant extract, to prepare fresh-keeping paper. Since oregano essential oil has a good antibacterial effect on bacteria, the fresh-keeping paper made from oregano essential oil can reduce food decay and has a good fresh-keeping effect.

[0016] 2. The present invention adopts cyclodextrin to embed essential oil. Under the embedding of cyclodextrin, the essential oil can reduce the contact with light, heat and oxygen, thereby improving its chemical stability and extending the shelf life. Cyclodextrin can be used as a controlled release carrier, and according to the interaction between cyclodextrin and essential oil, and external environmental conditions (such as temperature, humidity), the release rate and pattern of essential oil are adjusted to achieve a slow-release effect. And the embedding of cyclodextrin can increase the solubility of essential oil in aqueous medium, making it easier to be evenly distributed in the cling film. The embedding of cyclodextrin can reduce the volatilization loss of essential oil, maintain its effective concentration, and improve the fresh-keeping effect.

[0017] 3. The medicinal ingredients used in the present invention are natural plant essential oils, which are extracted by a pressing process and are natural, environmentally friendly and non-toxic.

[0018] 4. The fresh-keeping paper used in the present invention is easy to use and does not require measures such as soaking, spraying, and fumigation, which can greatly save labor costs and achieve food storage at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 is a diagram showing changes in appearance during fresh-keeping storage of Example 1 of the present invention and Control Group 1; Figure 2 is a graph showing changes in appearance during fresh-keeping storage of Example 2 of the present invention and Control Group 2; Figure 3 is a graph showing changes in appearance during fresh-keeping storage of Example 3 of the present invention and Control Group 3; Figure 4 is a graph showing changes in appearance during fresh-keeping storage of Example 4 of the present invention and Control Group 4; Figure 5 is a graph showing changes in appearance during fresh-keeping storage of Example 5 of the present invention and Control Group 5; Figure 6 is the change in the number of colonies during storage of Example 3 of the present invention and Control Group 3; Figure 7 is the change in the number of colonies during storage of Example 4 and Control Group 4 of the present invention; Figure 8 It is the change of colony count during storage of Example 5 of the present invention and Control Group 5. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1 This embodiment provides a method for preparing food antibacterial fresh-keeping paper based on plant essential oils, and the specific steps are as follows: S1. Dissolve 12 g of β-cyclodextrin in 100 ml of deionized water at 70 °C with stirring; S2, then 7 ml of cinnamon essential oil and ethanol were mixed in a weight ratio of 1:1 to obtain a mixed solution A, and the cyclodextrin solution was slowly added under heating and stirring at 70°C; S3, keep the mixed solution A in a water bath at 65-75°C and stir the solution to obtain a mixed solution B, and continue heating and stirring at 70°C for 2 h; S4. After the reaction is completed, the solution is allowed to stand at 4°C for 24 h, and the solution is centrifuged at 8000 r / min to remove the supernatant. S5, placing the obtained bottom solid into a freeze dryer, and drying to obtain microcapsules; S6, mix the microcapsules and PVA in a ratio of 1:3 and apply to 35g / m 3 The grapes are placed on paper and dried at 60°C to obtain fresh-keeping paper, which is then made into fresh-keeping bags to package the grapes and stored at room temperature for a period of time.

[0023] Example 2 This embodiment provides a method for preparing food antibacterial fresh-keeping paper based on plant essential oils, and the specific steps are as follows: S1. Dissolve 12 g of β-cyclodextrin in 100 ml of deionized water at 70 °C with stirring; S2, then 7 ml of cinnamon essential oil and ethanol were mixed in a weight ratio of 1:1 to obtain a mixed solution A, and the cyclodextrin solution was slowly added under heating and stirring at 70°C; S3, keep the mixed solution A in a water bath at 65-75°C and stir the solution to obtain a mixed solution B, and continue heating and stirring at 70°C for 2 h; S4. After the reaction is completed, the solution is allowed to stand at 4°C for 24 h, and the solution is centrifuged at 8000 r / min to remove the supernatant. S5, placing the obtained bottom solid into a freeze dryer, and drying to obtain microcapsules; S6, mix the microcapsules and PVA in a ratio of 1:3 and apply to 35g / m 3 The tomatoes are placed on paper and dried at 60°C to obtain fresh-keeping paper, which is then made into fresh-keeping bags to package the tomatoes and stored at room temperature for a period of time.

[0024] Example 3 This embodiment provides a method for preparing food antibacterial fresh-keeping paper based on plant essential oils, and the specific steps are as follows: S1. Dissolve 12 g of β-cyclodextrin in 100 ml of deionized water at 70 °C with stirring; S2, then 7 ml of cinnamon essential oil and ethanol were mixed in a weight ratio of 1:1 to obtain a mixed solution A, and the cyclodextrin solution was slowly added under heating and stirring at 70°C; S3, keep the mixed solution A in a water bath at 65-75°C and stir the solution to obtain a mixed solution B, and continue heating and stirring at 70°C for 2 h; S4. After the reaction is completed, the solution is allowed to stand at 4°C for 24 h, and the solution is centrifuged at 8000 r / min to remove the supernatant. S5, placing the obtained bottom solid into a freeze dryer, and drying to obtain microcapsules; S6, mix the microcapsules and PVA in a ratio of 1:3 and apply to 35g / m 3 The bread is wrapped in paper and dried at 60°C to obtain fresh-keeping paper, which is then made into fresh-keeping bags to package the bread and stored at room temperature for a period of time.

[0025] Example 4 A method for preparing food antibacterial fresh-keeping paper based on plant essential oil, the specific steps are as follows: S1. Dissolve 12 g of β-cyclodextrin in 100 ml of deionized water at 70 °C with stirring; S2, then 7 ml of cinnamon essential oil and ethanol were mixed in a weight ratio of 1:1 to obtain a mixed solution A, and the cyclodextrin solution was slowly added under heating and stirring at 70°C; S3, keep the mixed solution A in a water bath at 65-75°C and stir the solution to obtain a mixed solution B, and continue heating and stirring at 70°C for 2 h; S4. After the reaction is completed, the solution is allowed to stand at 4°C for 24 h, and the solution is centrifuged at 8000 r / min to remove the supernatant. S5, placing the obtained bottom solid into a freeze dryer, and drying to obtain microcapsules; S6, mix the microcapsules and PVA in a ratio of 1:3 and apply to 35g / m 3The paper is placed on a plastic wrapper and dried at 60°C to obtain a fresh-keeping paper, which is then made into a fresh-keeping bag to package the apples and stored at room temperature for a period of time.

[0026] Example 5 This embodiment provides a method for preparing food antibacterial fresh-keeping paper based on plant essential oils, and the specific steps are as follows: S1. Dissolve 12 g of β-cyclodextrin in 100 ml of deionized water at 70 °C with stirring; S2, then 7 ml of cinnamon essential oil and ethanol were mixed in a weight ratio of 1:1 to obtain a mixed solution A, and the cyclodextrin solution was slowly added under heating and stirring at 70°C; S3, keep the mixed solution A in a water bath at 65-75°C and stir the solution to obtain a mixed solution B, and continue heating and stirring at 70°C for 2 h; S4. After the reaction is completed, the solution is allowed to stand at 4°C for 24 h, and the solution is centrifuged at 8000 r / min to remove the supernatant. S5, placing the obtained bottom solid into a freeze dryer, and drying to obtain microcapsules; S6, mix the microcapsules and PVA in a ratio of 1:3 and apply to 35g / m 3 The pork is wrapped in paper and dried at 60°C to obtain fresh-keeping paper, which is then made into fresh-keeping bags to package the pork and stored at room temperature for a period of time.

[0027] Control group 1 The base paper is directly used to make packaging bags, which are then used to package grapes and placed at room temperature for a period of time (the same time as in Example 1).

[0028] Control group 2 The base paper is directly used to make a packaging bag, and the cherry tomatoes are then packaged in the packaging bag and placed at room temperature for a period of time (the same time as in Example 2).

[0029] Control group 3 The base paper is directly used to make packaging bags, which are then used to package bread and left at room temperature for a period of time (the same time as in Example 3).

[0030] Control group 4 The base paper is directly used to make packaging bags, which are then used to package apples and placed at room temperature for a period of time (the same time as in Example 4).

[0031] Control group 5 The base paper is directly used to make a packaging bag, and the pork is then packaged in the packaging bag and placed at room temperature for a period of time (the same time as in Example 5).

[0032] Effect evaluation experiment Decay rate, observe the number of decayed samples after the experiment, the decay rate is calculated as follows: ; Weight loss rate, measure the mass of the sample before and after the experiment, and the weight loss rate is calculated as follows: ; Determination of vitamin C content: Measured by 2,6-dichloroindophenol solution titration method, weigh 100g of the edible part of the fruit, crush it, add 100ml of extractant, and quickly pound it into a homogenous slurry. Weigh 10-40g of the slurry sample, transfer the sample into a 100ml volumetric flask with the extractant, dilute to the scale, shake well and filter. Pipette 10ml of the filtrate into a conical flask, and titrate with a calibrated 2,6-dichloroindophenol solution until the solution turns pink and does not fade for 15 seconds. The vitamin C calculation formula is as follows: ; Where, V is the volume of dye solution consumed when titrating the sample solution (ml); V0——the volume of dye solution consumed during the blank titration; T——2,6-dichloroindophenol dye titer, mg / ml; A——dilution multiple; W——sample weight, g.

[0033] Titratable acid content determination: Crush the fruit and dilute it. Add phenolphthalein as an indicator and titrate with standard sodium hydroxide solution until it turns pink and does not change color for 30 seconds. The titratable acid calculation formula is as follows: ; V—is the volume of the test sample, mL; V0—volume of the test part, ml; V1—volume of sodium hydroxide solution, ml; c—is the concentration of sodium hydroxide solution, mol / L.

[0034] When counting colonies, start counting from the plate with the lowest dilution. If the number of colonies on all plates is less than 30 CFU, count the number of colonies on all plates, but only use the colony counts on the two plates closest to 30 CFU to calculate the final colony count. If the number of colonies on all plates is greater than 30 CFU, only count the number of colonies on plates between 30 and 300 CFU; If the average colony counts of all dilutions are greater than 300, they cannot all be recorded as TNTC. The colony counts on the two plates with the highest dilution must be counted one by one and then the average is calculated; If no colonies grow on all plates, multiply the lowest dilution factor by less than 1.

[0035] Vitamin C is not only a nutrient in fruits, but also one of the abundant antioxidants in fruits, and is also an important indicator for measuring the freshness of fruits. It can be seen from Table 1 that the rot rate and weight loss rate of grapes in Example 1 are 12.5% ​​and 37.16%, and the rot rate and weight loss rate of grapes in Control Group 1 are 37.5% and 40.25%, which shows that fresh-keeping paper packaging can reduce the rot rate, thereby reducing the excessive loss of water due to skin damage.

[0036] like Figure 1 As shown, the vitamin C content in Example 1 is much higher than that in Control Group 1. Microorganisms consume a large amount of titratable acid during their growth and reproduction, which can reflect the storage quality of fruits and vegetables. Titratable acid will affect the consumption and sales of fruits. As can be seen from Table 1, the titratable acid content in Example 1 is higher than that in Experimental Group 1 because the cling film inhibits the growth of microorganisms and reduces the consumption of titratable acid.

[0037] Table 1 Control group 1 Example 1 Decay rate / % 37.5 12.5 Weight loss rate / % 40.25 37.16 Vitamin C content (mg / 100g) 2.27 4.36 Titratable acid content (mg / 100g) 5.46 8.87 It can be concluded from Table 2 that the rot rate and weight loss rate of small tomatoes in Example 2 are 22.2% and 34.87%, and the rot rate and weight loss rate of small tomatoes in Control Group 2 are 22.2% and 38.95%. It can be concluded that the fresh-keeping paper packaging can reduce the rot rate, thereby reducing the excessive loss of water due to peel damage.

[0038] like Figure 2 As shown in Table 2, the vitamin C content of Example 2 is much higher than that of Control Group 2. Microorganisms consume a large amount of titratable acid during their growth and reproduction, which can reflect the storage quality of fruits and vegetables. Titratable acid will affect the consumption and sales of fruits. It can be seen from Table 2 that the titratable acid content of Example 2 is higher than that of Experimental Group 2 because the cling film inhibits the growth of microorganisms and reduces the consumption of titratable acid.

[0039] Table 2 Control group 2 Example 2 Decay rate / % 33.3 22.2 Weight loss rate / % 38.95 34.87 Vitamin C content (mg / 100g) 1.77 2.15 Titratable acid content (mg / 100g) 8.33 11.23 like Figure 3 , Figure 6 As shown, the colony count changes of Example 3 and Control Example 3, it can be found that the colony counts of the Example and the Control Example were not much different in the first eleven days, but starting from the fourteenth day, the colony count of the Control Example increased rapidly, while the colony count of the Example increased slowly, which was because the cling film inhibited the growth of colonies.

[0040] like Figure 4 , Figure 7As shown, the colony count changes of Example 4 and Control Example 4. It can be found that the colony counts of the Example and the Control Example are not much different in the first eight days, but on the fourteenth day, the colony count of the Control Example is much larger than that of the Example. This is because the cling film can effectively inhibit bacterial growth.

[0041] like Figure 5 , Figure 8 As shown, the colony count changes of Example 5 and Control Example 5. It can be found that the colony counts of the Example and the Control Example were not much different in the first eight days, but the colony count of the Control Example increased rapidly from the eleventh day, while the growth of the Example was not obvious. This is because the cling film can effectively inhibit the growth of bacteria.

[0042] The food antibacterial fresh-keeping paper prepared by the above method has excellent fresh-keeping effect, which is mainly manifested in the preservation of grape tomatoes after picking, and the decay rate is found to be significantly reduced, and the consumption of vitamin C and titratable acid content is also reduced. In addition, the present invention also has the effect of reducing and preventing food moisture loss, and can also delay fruit softening and maintain the quality of fruits and vegetables when used for fruit and vegetable preservation. The essential oil used has an antibacterial effect, and oregano essential oil has a good antibacterial effect on Aspergillus niger, Escherichia coli and Staphylococcus aureus. In addition, this product can be directly used for food packaging, and can play a role in both transportation and storage processes.

[0043] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for preparing food antibacterial fresh-keeping paper based on plant essential oil, characterized in that: The following steps are involved: S1. First, β-cyclodextrin is dissolved in water, and stirred to dissolve in a water bath at 65-75° C. to obtain a β-cyclodextrin solution; S2, mixing oregano essential oil with ethanol to obtain a mixed solution A, and then adding the mixed solution A to the β-cyclodextrin solution of S1; S3, continuously maintaining the mixed solution A in a water bath at 65-75° C. and stirring the solution to obtain a mixed solution B; S4, allowing the mixed solution B to stand, and then removing the supernatant under centrifugal conditions to obtain the bottom solid; S5, drying the obtained bottom solid to obtain microcapsules; S6, after mixing the microcapsules and PVA, the coating amount is 20g / m 3 A proper amount of a mixed solution of microcapsules and PVA is applied to the surface of paper to form a continuous coating layer of the fresh-keeping solution to obtain fresh-keeping paper.

2. The method for preparing the food antibacterial fresh-keeping paper based on plant essential oil according to claim 1, characterized in that: In S1, the ratio of β-cyclodextrin to water is 12:

100.

3. The method for preparing the food antibacterial fresh-keeping paper based on plant essential oil according to claim 1, characterized in that: In S2, oregano essential oil and ethanol are mixed in a mass ratio of 1:

1.

4. The method for preparing the food antibacterial fresh-keeping paper based on plant essential oil according to claim 1, characterized in that: In the step S4, the mixed solution B is kept at a temperature of 3-5°C for 20-24 hours.

5. The method for preparing the food antibacterial fresh-keeping paper based on plant essential oil according to claim 1, characterized in that: In S2 and S3, the stirring speed is 800 r / min and the time is 2 h.

6. In S4, the centrifugal conditions are a rotation speed of 8000 r / min and a time of 2-3 min.

7. The method for preparing food antibacterial fresh-keeping paper based on plant essential oil according to claim 1, characterized in that: In S5, the bottom solid is dried under the following conditions: drying time of 72 h and temperature of -40°C.

8. The method for preparing food antibacterial fresh-keeping paper based on plant essential oil according to claim 1, characterized in that: In the S6, the mixing ratio of microcapsules and PVA is 1:

3.

9. The method for preparing the food antibacterial fresh-keeping paper based on plant essential oil according to claim 7, characterized in that: In S6, the PVA solution is prepared by adding PVA solid and deionized water at a mass ratio of 1:20 and mixing and dissolving them at 90°C.

10. The method for preparing food antibacterial fresh-keeping paper based on plant essential oil according to claim 7, characterized in that: In the above S6, after coating on the paper, the drying temperature is 60° C. and the drying time is 6 minutes.

Images