A method for fruit and vegetable micro-perforated packaging by optimizing laser perforation parameters using a mathematical model

Abstract

The present application relates to a kind of fruit and vegetable microporous packaging methods for optimizing laser perforation parameters using mathematical model, comprising the following steps: step 1, selecting fruit and vegetable;Step 2, determining the mass of CO2 generated by fruit and vegetable, calculating the respiratory intensity of fruit and vegetable;Step 3, with different microporous aperture as variable, simulate punching, determine the microporous aperture of minimum marginal effect;Step 4, the respiratory intensity and microporous aperture d are substituted into Del-Valle equation, the number of microporous of microporous packaging is obtained, and PP film is perforated by laser perforating machine, to obtain the required microporous film;Step 6, fruit and vegetable are packaged with microporous film.The microporous packaging designed in the present application can maintain the gas permeability required for normal physiological consumption of fruit and vegetable, effectively reduce the hypoxic injury and anaerobic respiration of fruit and vegetable, and is beneficial to maintain the storage quality of fruit and vegetable products and prolong the storage period.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fruit and vegetable packaging, in particular to a fruit and vegetable micro-hole packaging method using mathematical model to optimize laser perforation parameters. BACKGROUND

[0002] Fruits and vegetables contain rich basic nutrients, and excessive aerobic or anaerobic respiration will have a negative impact on the quality of fruits and vegetables, especially anaerobic respiration. Modified atmosphere packaging (MAP) and controlled atmosphere (CA) technology have become popular methods in the field of fruit preservation. These technologies help to regulate the atmosphere around the fruit, which can greatly improve its storage performance. Pan Leiqing et al. (2011) disclosed a "fresh-cut lettuce high-carbon dioxide modified atmosphere packaging preservation method" (application publication number: CN 102144659A), which performs high-carbon dioxide modified atmosphere packaging on fresh-cut lettuce, with the gas volume percentage composition being 10% oxygen, 10-50% carbon dioxide, and 40-80% nitrogen. The shelf life of fresh-cut lettuce stored at 0-4℃ can reach more than 15 days. However, high concentrations of CO2 in the package can enhance the anaerobic respiration of fruits and vegetables, causing anaerobic stress, producing odors, and causing nutrient loss and quality decline.

[0003] MAP without micro-holes is not suitable for preserving high-respiration-rate fruits and vegetables, because the high CO2 produced and the low gas permeability of the film will cause anaerobic stress to the fruits and vegetables. In general, films with higher permeability often lack transparency, hardness, and durability, and cannot meet the normal packaging requirements. In order to solve this problem, micro-hole modified atmosphere packaging is used to maintain the storage quality of fruits and vegetables. Micro-hole film is the key to regulating gas permeability and CO2, O2, and relative humidity (RH) balance.

[0004] Micro-hole film has low processing cost and can be adjusted according to the specific preservation needs of different fruits. Micro-hole film is an effective choice to achieve gas balance in MAP of high-respiration-rate products, and has been widely used in the preservation of fruits, vegetables, and mushrooms. Micro-hole film can enhance the gas permeability of the packaging film, prevent anaerobic respiration of fresh food, and prevent the formation of condensate inside the film, which helps to inhibit the growth of microorganisms and spoilage. Zhang Lin et al. (2019) disclosed a "method for extending the shelf life of fruits and vegetables by laser perforation to adjust micro-holes combined with modified atmosphere packaging and respiratory model" (application publication number: CN 110810499A), which uses a micro-hole packaging bag to package fresh-cut fruits and vegetables, and uses the Michaelis-Menten model to predict the respiration rate of fruits and vegetables, which can extend the shelf life of fruits and vegetables to 16-21 days. However, the respiration rate model is only applicable to a specific state of a specific fruit and vegetable, and has no direct relationship with the number of micro-holes, and has little significance.

[0005] The gas permeability of microporous membranes is affected by various perforation techniques. Microporous membranes can be perforated by a variety of methods, but mechanical needle perforation is popular due to its flexibility and cost-effectiveness. However, it is difficult to guarantee precision, and the resulting micropore shapes are irregular, which can affect gas flow rates. Summary of the Invention

[0006] The purpose of this invention is to provide a method for microporous packaging of fruits and vegetables using mathematical models to optimize laser perforation parameters. This method optimizes perforation parameters and designs microporous packaging specifically for fruits and vegetables using mathematical models such as the Fick model and the Del-Valle equation. This method has the advantages of being rapid, scientific, and universally applicable. The designed microporous packaging can maintain the gas permeability required for the normal physiological consumption of fruits and vegetables, effectively reducing hypoxia damage and anaerobic respiration, thus helping to maintain the storage quality of fruit and vegetable products and extend their shelf life.

[0007] The technical solution of this invention:

[0008] A method for microporous packaging of fruits and vegetables that utilizes a mathematical model to optimize laser perforation parameters includes the following steps:

[0009] Step 1: Select fruits and vegetables that are of good quality, intact, and free from mechanical damage; wash, disinfect, and drain them.

[0010] Step 2: Place the fruits and vegetables obtained in Step 1 into a sealed container, and use a CO2 gas analyzer to measure the mass of CO2 produced per unit mass of fruits and vegetables per unit time, and calculate the respiration rate of fruits and vegetables at 0-30℃. ;

[0011] Step 3: Simulate drilling using different micropore sizes as variables to determine the range of micropore sizes and the spacing between micropores that conform to the Fick diffusion model. Substitute different pore sizes within the range of the Fick diffusion model into the marginal effect model. Determine the micropore size that minimizes marginal effects. .

[0012] Step 4: Combine the respiration intensity (RR) of the fruits and vegetables obtained in Step 2 with the micropore size obtained in Step 3. Substituting into the Del-Valle equation Combined with the molecular diffusion coefficient of CO2 in the air The number of micropores in the microporous packaging was determined. In the equation Represents the number of micropores. Represents film thickness. Represents the pore size of the micropores. The molecular diffusion coefficient representing CO2 in the air. and These represent the partial pressures of CO2 inside and outside the packaging, respectively. It is a thermodynamic constant. Kelvin temperature, For fruit quality, The respiration rate of the fruit.

[0013] Step 5: Calculate the number of micropores obtained in Step 4. The PP film is perforated using a laser perforation machine to obtain the desired microporous membrane;

[0014] Step 6: Place a certain amount of fruits and vegetables into a PP tray for microporous film packaging, and store the packaged fruits and vegetables at 0-30℃.

[0015] Furthermore, in step 2, Kelvin temperature and fruit respiration rate refer to the storage temperature of the fruits and vegetables and the respiration rate at that storage temperature.

[0016] Furthermore, the Fick diffusion model in step (3) is: In the model Let K be the permeation coefficient of CO2 through the PP membrane, and K be the marginal effect value. (Marginal effect model)

[0017] middle, This indicates the amount of CO2 gas that diffuses through the micropores per unit time.

[0018] Furthermore, the micropore size mentioned in step (3) The size ranges from 50 to 500 μm, with a horizontal spacing of 50 mm and a vertical spacing of 20 mm.

[0019] Furthermore, when the temperatures in step (4) are set to 20℃ and 2℃ respectively, they are substituted into the calculation equation Del-Valle: The number of micropores obtained were 20 and 9, respectively.

[0020] Furthermore, the processing parameters of the laser perforation machine in step 5 are as follows: processing power (10 W-16 W), processing times (19-33), and focal length (326 mm).

[0021] The present invention has the following beneficial effects:

[0022] 1. This invention calculates a reasonable number of micropores through a mathematical model, which can effectively ensure that the gas concentration inside the packaging is within a reasonable range, achieving the effect of modified atmosphere packaging, avoiding physiological damage caused by anaerobic respiration, thereby effectively extending the shelf life of fruits and vegetables and maintaining their quality.

[0023] 2. The perforation parameters required for microporous packaging are calculated using the Dal-Valle equation, and microporous packaging for fruits and vegetables is designed. This method is different from the empirical formulas obtained through trial and error or random experiments in the past. It has the characteristics of being fast, scientific and universal, and can prepare microporous membranes with different perforation parameters according to the respiratory needs of different fruits and vegetables.

[0024] 3. Using the Fick diffusion model and the marginal effect model to determine the micropore size with the minimum marginal effect is scientific and reasonable, and can ensure that gas diffusion is not affected by the marginal effect during the micropore packaging process.

[0025] 4. Use a CO2 laser perforation machine to perforate PP film to prepare microporous membranes. Laser perforation is precise and fast, and can accurately determine the perforation area of ​​the film to ensure precise controlled atmosphere effect.

[0026] 5. Using laser technology for thin film perforation is different from traditional physical and chemical perforation techniques. It can overcome the requirements of film thickness and material on perforation technology and is suitable for organic thin films of various thicknesses and materials.

[0027] 6. Pore diameter of the micropores prepared by this method With a diameter of 50-500 μm, it can cover the micropore range of packaging for most fruit and vegetable products.

[0028] 7. The microporous membrane designed and prepared using this method can effectively remove CO2 produced by the respiration of winter jujubes during storage, avoiding physiological damage caused by excessive CO2 accumulation. The microporous packaging can inhibit the reddening of winter jujubes and the browning of the pulp, effectively extending the storage period.

[0029] 8. The microporous membrane prepared by the method design not only ensures accuracy, but also produces micropores with regular shapes, avoiding the influence of micropores on gas flow rate.

[0030] 9. This method has the advantages of being fast, scientific and universal. The designed microporous packaging can maintain the gas permeability required for the normal physiological consumption of fruits and vegetables, effectively reduce the hypoxia damage and anaerobic respiration of fruits and vegetables, and help maintain the storage quality of fruit and vegetable products and extend the storage period. Attached Figure Description

[0031] Figure 1 Photos and reddening rate of winter jujubes packaged in microporous packaging at 20℃ and 2℃;

[0032] Figure 2 The fitting equation for the influence of different processing parameters on micropore diameter and perforation effect;

[0033] Figure 3 The study investigated the changes in O2 and CO2 content within the microporous packaging and the changes in the respiration rate of winter jujubes.

[0034] Figure 4 The changes in the storage quality of winter jujubes under microporous packaging. Detailed Implementation

[0035] The specific embodiments of the present invention are described below with reference to the accompanying drawings and examples:

[0036] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0037] The effectiveness of microporous membranes largely depends on their pore area, making it difficult to find the optimal solution for a specific product. Some studies employ trial-and-error and exhaustive methods to test films with various pore sizes, which can be inefficient due to the vast number of possible combinations of packaging films and pore sizes. Furthermore, respiration rates vary significantly between different batches of products due to differences in growth conditions and ripening stages. Even if a solution proves effective for one batch through trial and error, it may not be effective for another. After careful consideration of Fick's diffusion law, the Del-Valle expression, Stephan-Maxwell's diffusion law, and empirical models, the Del-Valle expression was ultimately chosen for its simplicity and accuracy. The Del-Valle expression is a mathematical model that calculates the number of micropores required for packaging permeation based on the respiration rate of fruits and vegetables and the mass transfer of gas within the film. The purpose of this invention is to develop a method for preparing and designing microporous film packaging for preserving fruits and vegetables with high respiration rates, enabling the packaging to maintain optimal O2 or CO2 gas concentrations. This represents an innovative exploration in food preservation packaging applications. To achieve this goal, we used fruits and vegetables as the main raw materials, calculated the number of micropores using the Del-Valle expression, and then used a CO2 laser perforation machine to manufacture microporous membranes specifically for fruits and vegetables. We further studied the application of these microporous membranes.

[0038] A method for microporous packaging of fruits and vegetables that utilizes a mathematical model to optimize laser perforation parameters includes the following steps:

[0039] Step 1: Select fruits and vegetables that are of good quality, intact, and free from mechanical damage; wash, disinfect, and drain them.

[0040] Step 2: Place the fruits and vegetables obtained in Step 1 into a sealed container, and use a CO2 gas analyzer to measure the mass of CO2 produced per unit mass of fruits and vegetables per unit time, and calculate the respiration rate of fruits and vegetables at 0-30℃. ;

[0041] Step 3: Simulate drilling using different micropore sizes as variables to determine the range of micropore sizes and the spacing between micropores that conform to the Fick diffusion model. Substitute different pore sizes within the range of the Fick diffusion model into the marginal effect model. Determine the micropore size that minimizes marginal effects. .

[0042] Step 4: Combine the respiration intensity (RR) of the fruits and vegetables obtained in Step 2 with the micropore size obtained in Step 3. Substituting into the Del-Valle equation Combined with the molecular diffusion coefficient of CO2 in the air The number of micropores in the microporous packaging was determined. .

[0043] Step 5: Calculate the number of micropores obtained in Step 4. The PP film is perforated using a laser perforation machine to obtain the desired microporous membrane;

[0044] Step 6: Place a certain amount of fruits and vegetables into a PP tray for microporous film packaging, and store the packaged fruits and vegetables at 0-30℃.

[0045] Specifically, in step 2, Kelvin temperature and fruit respiration rate refer to the storage temperature of fruits and vegetables and the respiration rate at that storage temperature.

[0046] Specifically, the Fick diffusion model in step (3) is: In the model Let K be the permeation coefficient of CO2 through the PP membrane, and K be the marginal effect value. (Marginal effect model) middle, This indicates the amount of CO2 gas that diffuses through the micropores per unit time.

[0047] Specifically, the micropore size mentioned in step (3) The size ranges from 50 to 500 μm, with a horizontal spacing of 50 mm and a vertical spacing of 20 mm.

[0048] Specifically, when the temperature in step (4) is set to 20℃ and 2℃ respectively, the results are substituted into the calculation equation Del-Valle: In the equation Represents the number of micropores. Represents film thickness. Represents the pore size of the micropores. The molecular diffusion coefficient representing CO2 in the air. and These represent the partial pressures of CO2 inside and outside the packaging, respectively. It is a thermodynamic constant. Kelvin temperature, For fruit quality, To determine the fruit respiration rate, the number of micropores was found to be 20 and 9, respectively.

[0049] Specifically, the processing parameters of the laser perforation machine in step 5 are as follows: processing power (10 W-16 W), number of processing times (19-33), and focal length (326 mm).

[0050] Example 1

[0051] The selection of laser perforation aperture is mainly influenced by three factors: the focal length of the laser marking field lens, the processing power, and the number of processing passes, such as... Figure 2 The interaction of these factors determines different aperture sizes. To find suitable parameters for producing the desired aperture size, we conducted multiple piercing experiments and ultimately determined the ideal parameter range. Based on the experimental results, we determined the piercing processing power to be 12.5 W, the number of passes to be 25, and the focal length to be 326 mm, all of which were calculated using fitted equations.

[0052] Simulated drilling was performed with different pore sizes as variables to determine the range of micropore sizes that conform to Fick's diffusion theory and the spacing between micropores. Results showed that when the micropore size is no greater than 100 μm and... When the distance between the micropores is ≥100λ (λ is the spacing between the micropores), gas permeation through the microporous membrane follows Fick's diffusion theorem. Furthermore, the marginal effect is minimized when the micropore diameter is 100 μm. The marginal effect at the micropore ends refers to the fact that the partial pressure of O2 is not uniform around the pore; it is lower at the pore edges than elsewhere. This reduces the gas diffusion rate and increases the diffusion time. Therefore, after comprehensive consideration, a micropore diameter of 100 μm is chosen.

[0053] A method for microporous packaging of fruits and vegetables that utilizes a mathematical model to optimize laser perforation parameters includes the following steps:

[0054] Step 1: Select fruits and vegetables that are of good quality, intact, and free from mechanical damage; wash, disinfect, and drain them.

[0055] Step 2: Place the fruits and vegetables obtained in Step 1 into a sealed container, and use a CO2 gas analyzer to measure the mass of CO2 produced per unit mass of fruits and vegetables per unit time, and calculate the respiration rate of the fruits and vegetables at 20℃. ;

[0056] Step 3: Simulate drilling using different micropore sizes as variables to determine the range of micropore sizes and the spacing between micropores that conform to the Fick diffusion model. Substitute different pore sizes within the range of the Fick diffusion model into the marginal effect model. Determine the micropore size that minimizes marginal effects. .

[0057] Step 4: Combine the respiration intensity (RR) of the fruits and vegetables obtained in Step 2 with the micropore size obtained in Step 3. Substituting into the Del-Valle equation Combined with the molecular diffusion coefficient of CO2 in the air The number of micropores in the microporous packaging was determined. .

[0058] Step 5: Calculate the number of micropores obtained in Step 4. The PP film is perforated using a laser perforation machine to obtain the desired microporous membrane;

[0059] Step 6: Place a certain amount of fruits and vegetables into a PP tray for microporous film packaging, and store the packaged fruits and vegetables at 0~30℃.

[0060] Specifically, in step 2, Kelvin temperature and fruit respiration rate refer to the storage temperature of fruits and vegetables and the respiration rate at that storage temperature.

[0061] Specifically, the Fick diffusion model in step (3) is: In the model Let K be the permeation coefficient of CO2 through the PP membrane, and K be the marginal effect value. (Marginal effect model) middle, This indicates the amount of CO2 gas that diffuses through the micropores per unit time.

[0062] Specifically, the micropore size mentioned in step (3) The size ranges from 50 to 500 μm, with a horizontal spacing of 50 mm and a vertical spacing of 20 mm.

[0063] Specifically, the temperature in step (4) is set to 20°C, and substituted into the calculation equation Del-Valle: In the equation Represents the number of micropores. Represents film thickness. Represents the pore size of the micropores. The molecular diffusion coefficient representing CO2 in the air. and These represent the partial pressures of CO2 inside and outside the packaging, respectively. It is a thermodynamic constant. Kelvin temperature, For fruit quality, The number of micropores was 20, representing the fruit's respiration rate.

[0064] Specifically, the processing parameters of the laser perforation machine in step 5 are as follows: processing power (10 W-16 W), number of processing times (19-33), and focal length (326 mm).

[0065] Freshly ripened, green, intact winter jujubes without mechanical damage were washed, disinfected, drained, and placed in PP trays. Three packaging treatments were applied: microporous, conventional macroporous (6 mm pore size, 3 pores), and conventional non-porous packaging. Each treatment was repeated three times. The respiration rate of the winter jujubes was measured at 20℃, and the respiration rate was 16.2855 mg / kg / h. The respiration rate of the winter jujubes at 20℃ was calculated using the Dal-Valle equation, yielding a required number of micropores of 20. All three packaging methods were stored at 20℃ and 98% relative humidity under constant temperature and humidity. Samples were taken from the stored winter jujubes at 24-hour intervals, and the average value of the three biological replicates was taken.

[0066] like Figure 3 As shown, the O2 and CO2 levels inside the microporous membrane packaging rapidly reached equilibrium at 20°C and remained at a low level throughout, while the respiration rate was also significantly suppressed. Figure 4 c shows the effect of packaging on the weight loss of jujubes. Traditional large-pore packaging resulted in the largest weight loss, with the percentage weight loss at 20°C being 0.30%, 0.26%, and 0.15% for the traditional large-pore packaging group, the microporous packaging group, and the traditional non-porous packaging group, respectively. Figure 4 The microporous membrane packaging effectively reduces the loss of firmness caused by transpiration. Under microporous packaging, the firmness of winter jujubes is best maintained, inhibiting softening caused by anaerobic respiration. Figure 4 As shown in Figure e, on day 5 at 20℃, the soluble solids content of jujubes in microporous packaging was 5% and 6.9% higher than that in traditional large-pore packaging and traditional non-porous packaging, respectively. This indicates that microporous packaging can inhibit the accumulation of soluble solids in the early stages of jujube fruit development. Figure 4 As shown in g, microporous packaging inhibited the synthesis of titratable acids in fruits and vegetables in the early stage and their degradation in the later stage. Figure 1 As shown, at 20℃, the reddening rate of jujubes in the three storage packages showed a continuous increasing trend, reaching its maximum on the 5th day, at 35.33%, 19.41%, and 62.69%, respectively. Microporous packaging significantly inhibited the reddening of jujubes. Therefore, microporous membrane packaging can effectively maintain the quality of jujubes and extend their shelf life. Microporous membrane packaging at this temperature is suitable for storage at room temperature.

[0067] Example 2

[0068] The selection of laser perforation aperture is mainly influenced by three factors: the focal length of the laser marking field lens, the processing power, and the number of processing passes, such as... Figure 2The interaction of these factors determines different aperture sizes. To find suitable parameters for producing the desired aperture size, we conducted multiple piercing experiments and ultimately determined the ideal parameter range. Based on the experimental results, we determined the piercing processing power to be 12.5 W, the number of passes to be 25, and the focal length to be 326 mm, all of which were calculated using fitted equations.

[0069] Simulated drilling was performed with different pore sizes as variables to determine the range of micropore sizes that conform to Fick's diffusion theory and the spacing between micropores. Results showed that when the micropore size is no greater than 100 μm and... When the distance between the micropores is ≥100λ (λ is the spacing between the micropores), gas permeation through the microporous membrane follows Fick's diffusion theorem. Furthermore, the marginal effect is minimized when the micropore diameter is 100 μm. The marginal effect at the micropore ends refers to the fact that the partial pressure of O2 is not uniform around the pore; it is lower at the pore edges than elsewhere. This reduces the gas diffusion rate and increases the diffusion time. Therefore, after comprehensive consideration, a micropore diameter of 100 μm is chosen.

[0070] A method for microporous packaging of fruits and vegetables that utilizes a mathematical model to optimize laser perforation parameters includes the following steps:

[0071] Step 1: Select fruits and vegetables that are of good quality, intact, and free from mechanical damage; wash, disinfect, and drain them.

[0072] Step 2: Place the fruits and vegetables obtained in Step 1 into a sealed container, and use a CO2 gas analyzer to measure the mass of CO2 produced per unit mass of fruits and vegetables per unit time, and calculate the respiration rate of the fruits and vegetables at 20℃. ;

[0073] Step 3: Simulate drilling using different micropore sizes as variables to determine the range of micropore sizes and the spacing between micropores that conform to the Fick diffusion model. Substitute different pore sizes within the range of the Fick diffusion model into the marginal effect model. Determine the micropore size that minimizes marginal effects. .

[0074] Step 4: Combine the respiration intensity (RR) of the fruits and vegetables obtained in Step 2 with the micropore size obtained in Step 3. Substituting into the Del-Valle equation Combined with the molecular diffusion coefficient of CO2 in the air The number of micropores in the microporous packaging was determined. .

[0075] Step 5: Calculate the number of micropores obtained in Step 4. The PP film is perforated using a laser perforation machine to obtain the desired microporous membrane;

[0076] Step 6: Place a certain amount of fruits and vegetables into a PP tray for microporous film packaging, and store the packaged fruits and vegetables at 2℃.

[0077] Specifically, in step 2, Kelvin temperature and fruit respiration rate refer to the storage temperature of fruits and vegetables and the respiration rate at that storage temperature.

[0078] Specifically, the Fick diffusion model in step (3) is: In the model Let K be the permeation coefficient of CO2 through the PP membrane, and K be the marginal effect value. (Marginal effect model) middle, This indicates the amount of CO2 gas that diffuses through the micropores per unit time.

[0079] Specifically, the micropore size mentioned in step (3) The size ranges from 50 to 500 μm, with a horizontal spacing of 50 mm and a vertical spacing of 20 mm.

[0080] Specifically, the temperature in step (4) is set to 2℃, and substituted into the calculation equation Del-Valle: In the equation Represents the number of micropores. Represents film thickness. Represents the pore size of the micropores. The molecular diffusion coefficient representing CO2 in the air. and These represent the partial pressures of CO2 inside and outside the packaging, respectively. It is a thermodynamic constant. Kelvin temperature, For fruit quality, The number of micropores was 9, representing the fruit's respiration rate.

[0081] Specifically, the processing parameters of the laser perforation machine in step 5 are as follows: processing power (10 W-16 W), number of processing times (19-33), and focal length (326 mm).

[0082] Freshly ripened, green, intact winter jujubes without mechanical damage were washed, disinfected, drained, and placed in PP trays. Three packaging treatments were applied: micropore packaging, conventional macropore packaging (6 mm pore size, 3 pores), and conventional non-porous packaging. Each treatment was repeated three times. The respiration rate of the winter jujubes was measured at 2℃, and the respiration rate was 5.5836 mg / kg / h. The required number of micropores was calculated to be 9 by substituting the respiration rate of the winter jujubes at 2℃ into the Dal-Valle equation. All three treatments were stored at 2℃ and 98% relative humidity under constant temperature and humidity. Samples were taken from the stored winter jujubes at 7-day intervals, and the average value of the three biological replicates was taken.

[0083] like Figure 3 As shown, the O2 and CO2 levels inside the microporous membrane packaging rapidly reached equilibrium at 2°C and remained at a low level throughout, while the respiration rate was also significantly suppressed. Figure 4 Figure d shows the effect of packaging on the weight loss of jujubes. The traditional large-pore packaging resulted in the greatest weight loss, with the percentage weight loss at 2°C being 0.34%, 0.11%, and 0.20% for the traditional large-pore packaging group, the micropore packaging group, and the traditional non-pore packaging group, respectively. Figure 4 b shows that microporous membrane packaging effectively reduces the loss of firmness caused by transpiration. Under microporous packaging, the firmness of winter jujubes is best maintained, inhibiting softening caused by anaerobic respiration. For example... Figure 4 As shown in f, the decrease in soluble solids was smallest in microporous packaging at 2℃. On day 35, the TSS of jujubes packaged with microporous packaging was 3.9% and 8.2% higher than that of traditional large-pore packaging and traditional non-porous packaging, respectively. This indicates that microporous packaging can inhibit the synthesis of soluble solids and reduce their content in the early stages of jujube fruit development. Figure 4 As shown in h, microporous packaging inhibited the synthesis of titratable acids in fruits and vegetables in the early stage and their degradation in the later stage. Figure 1 As shown, at 2℃, the reddening rate of jujubes in the three storage packages showed a continuous increasing trend. The reddening rate and rot rate of traditional non-porous packaging eventually reached 97% and 80%, respectively, while microporous packaging significantly inhibited the reddening of jujubes. Therefore, this indicates that microporous membrane packaging can effectively maintain the quality of jujubes and extend their shelf life. Microporous membrane packaging at this temperature is suitable for cold chain transportation.

[0084] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that modifications and improvements can be made to these embodiments without departing from the principles and spirit of the present invention as defined by the claims and their equivalents, and such modifications and improvements should also be within the scope of protection of the present invention.

Claims

1. A method for microporous packaging of fruits and vegetables using a mathematical model to optimize laser perforation parameters, characterized in that: Includes the following steps: Step 1: Select fruits and vegetables that are of good quality, intact, and free from mechanical damage; wash, disinfect, and drain them. Step 2: Place the fruits and vegetables obtained in Step 1 into a sealed container, and use a CO2 gas analyzer to measure the mass of CO2 produced per unit mass of fruits and vegetables per unit time, and calculate the respiration rate of fruits and vegetables at 0-30℃. ; Step 3: Simulate drilling using different micropore sizes as variables to determine the range of micropore sizes and the spacing between micropores that conform to the Fick diffusion model. Substitute different pore sizes within the range of the Fick diffusion model into the marginal effect model. Determine the micropore size that minimizes marginal effects. ; Fick diffusion model is In the model Let K be the permeation coefficient of CO2 through the PP membrane, and K be the marginal effect value. (Marginal effect model) middle, This indicates the amount of CO2 gas that diffuses through the micropores per unit time. Step 4: Combine the respiration intensity (RR) of the fruits and vegetables obtained in Step 2 with the micropore size obtained in Step 3. Substituting into the Del-Valle equation Combined with the molecular diffusion coefficient of CO2 in the air The number of micropores in the microporous packaging was determined. In the equation Represents the number of micropores. Represents film thickness. Represents the pore size of the micropores. The molecular diffusion coefficient representing CO2 in the air. and These represent the partial pressures of CO2 inside and outside the packaging, respectively. It is a thermodynamic constant. Kelvin temperature, For fruit quality, The fruit's respiration rate; Step 5: Calculate the number of micropores obtained in Step 4. The PP film is perforated using a laser perforation machine to obtain the desired microporous membrane; Step 6: Place a certain amount of fruits and vegetables into a PP tray for microporous film packaging, and store the packaged fruits and vegetables at 0-30℃.

2. The method for microporous packaging of fruits and vegetables using a mathematical model to optimize laser perforation parameters according to claim 1, characterized in that: In step 2, Kelvin temperature and fruit respiration rate refer to the storage temperature of fruits and vegetables and the respiration rate at that storage temperature.

3. The method for microporous packaging of fruits and vegetables using a mathematical model to optimize laser perforation parameters according to claim 1, characterized in that: The micropore size in step (3) The size ranges from 50 to 500 μm, with a horizontal spacing of 50 mm and a vertical spacing of 20 mm.

4. The method for microporous packaging of fruits and vegetables using a mathematical model to optimize laser perforation parameters according to claim 1, characterized in that: When the temperatures in step (4) are set to 20℃ and 2℃ respectively, they are substituted into the calculation equation Del-Valle: The number of micropores obtained were 20 and 9, respectively.

5. The method for microporous packaging of fruits and vegetables using a mathematical model to optimize laser perforation parameters according to claim 1, characterized in that: In step 5, the processing parameters of the laser perforation machine are as follows: processing power 10 W-16 W, processing times 19-33 times, and focal length 326 mm.

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