Irradiation sterilization method for fruits
By using high-energy electron beam irradiation, modified atmosphere assisted environment, and coating treatment, the problems of fruit quality deterioration and limited preservation effect in traditional irradiation technology have been solved, achieving efficient sterilization and preservation effects, and making it suitable for large-scale application of different fruits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN QUANZHOU QUNENG TECH CO LTD
- Filing Date
- 2026-04-17
- Publication Date
- 2026-05-26
AI Technical Summary
Traditional irradiation technology can easily lead to deterioration of fruit quality, has a limited preservation effect and lacks specificity for different fruits, making it difficult to achieve both sterilization and quality maintenance.
High-energy electron beam irradiation combined with modified atmosphere and coating treatment is used. The appropriate irradiation dose is selected according to the fruit variety, size and maturity. The gas concentration and humidity are controlled during depressurized storage to form a semi-permeable protective film.
It achieves efficient sterilization, inhibits fruit respiration and metabolism, maintains the unique flavor and nutritional value of the fruit, extends the shelf life, and is suitable for large-scale application.
Smart Images
Figure CN122074545A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of food preservation technology, and in particular to a method for irradiating and sterilizing fruits. Background Technology
[0002] Fruits are prone to spoilage and deterioration after harvest due to physiological metabolic activities (such as respiration and ethylene production) and microbial infection, resulting in significant economic losses. Traditional preservation technologies such as low-temperature refrigeration, modified atmosphere packaging, and chemical disinfectants, while effective to some extent, suffer from problems such as high energy consumption, chemical residues, and incomplete treatment. In recent years, irradiation technology, as a non-thermal sterilization method, has shown potential in the field of fruit and vegetable preservation. Among them, high-energy electron beam irradiation, due to its advantages such as no radioactive residues, high processing efficiency, and controllable penetration, is gradually replacing some chemical treatments and isotope irradiation, becoming a research hotspot. In existing technologies, electron beam irradiation mostly uses fixed-dose treatment. Although it can inhibit microbial growth, it has obvious limitations: fixed doses cannot be adapted to differences in different fruit varieties, ripeness, or initial microbial loads, easily leading to incomplete sterilization with low-dose treatments or causing fruit tissue damage (such as browning and nutrient loss) with high doses.
[0003] Chinese Patent Publication No. CN114747610A discloses a method for preserving mangoes by electron beam irradiation. This method involves irradiating the mangoes in an ultrasonic and electron beam environment. The invention incorporates ultrasonic energy into the electron beam irradiation process, causing the electron beam, which absorbs the ultrasonic energy, to form an active vibration, thereby improving the preservation quality and effect of electron beam irradiated mangoes. However, this preservation method lacks specificity for different fruits.
[0004] Chinese Patent Publication No. CN103859006A discloses a method for preserving and quarantining fruit, comprising the following steps: a) packing fruit into boxes; b) subjecting the fruit boxes to electron beam irradiation: the total electron beam irradiation dose is 0.3-2.0 kGy, the total number of electron beam irradiations is 1-4, and the single electron beam irradiation dose is 0.3-0.6 kGy; c) depressurized storage: subjecting the electron beam irradiated fruit boxes to depressurized storage. This invention employs low-dose, multi-stage electron beam irradiation combined with depressurized treatment, which can effectively inhibit or kill microorganisms, pests, and their enzyme activity in fruit, thereby achieving a more effective extension of fruit shelf life and quarantine purposes. Furthermore, in actual production, it does not require damaging the original packaging of the fruit, making it convenient to operate and possessing strong processing capacity. However, this method does not apply a coating to the irradiated fruit, making it difficult to simultaneously achieve sterilization and quality maintenance. Summary of the Invention
[0005] Therefore, in view of the above problems, the present invention provides a method for irradiation sterilization of fruit, which solves the problems that traditional irradiation technology is prone to causing fruit quality deterioration, has a single preservation effect and lacks specificity for different fruits, and is difficult to achieve both sterilization and quality maintenance.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for irradiating and sterilizing fruit includes the following steps: S1. Fruit pretreatment and grading: Select fresh target fruits without serious mechanical damage or pests and diseases, sort and clean them, and grade them according to variety, size and ripeness. S2. High-energy electron beam irradiation treatment: The fruit treated in step S1 is placed on a conveyor belt and irradiated with a high-energy electron beam generated by an electron accelerator to sterilize insect eggs. The energy of the high-energy electron beam used in the high-energy electron beam irradiation treatment is 10 MeV. The irradiation dose is selected according to the storage resistance category of the fruit after grading in step S1: the irradiation dose for perishable fruits is 1.0-1.5 kGy, and the irradiation dose for storage-resistant fruits is 0.1-0.5 kGy. S3. Post-irradiation treatment and storage: The irradiated fruit is coated with a film, then packaged and stored.
[0007] The storage is a reduced-pressure storage method, with the absolute vacuum pressure controlled at 50-70 kPa, relative humidity at 85-95%, and storage temperature at 10-15℃. Simultaneously, a gas circulation system is activated, controlling the gas circulation flow rate at 1.0-1.5 m / s, and a mixture of sterile air and modified atmosphere gas is introduced every 2 hours. The mixed gas has an oxygen volume concentration of 3-5% and a carbon dioxide volume concentration of 5-8%, with each air exchange filling 20% of the storage chamber volume. This maintains a low-oxygen, suitable carbon dioxide concentration, and stable humidity environment, thereby synergistically inhibiting fruit respiration and microbial growth, and extending the shelf life.
[0008] Furthermore, the electron beam scanning method is dynamic scanning with a repetition frequency of 5-581Hz; the electron beam current intensity is 0-2mA; the conveyor belt speed is 20-180mm / s; the irradiation environment temperature is controlled at 20-35℃, and the relative humidity is controlled at 40-80%.
[0009] Furthermore, in step S2, before the high-energy electron beam irradiation treatment, a modified atmosphere-assisted irradiation environment construction step is also included, and the fruit treated in step S1 is placed in the modified atmosphere-assisted irradiation environment for irradiation. The oxygen and carbon dioxide volume concentrations in the modified atmosphere irradiation environment are adjusted according to the respiratory characteristics of the graded fruits: for perishable fruits with high respiratory intensity, the oxygen volume concentration is set at 3-5% and the carbon dioxide volume concentration at 5-10%; for tropical and subtropical fruits with low respiratory intensity, the oxygen volume concentration is set at 2-4% and the carbon dioxide volume concentration at 3-8%.
[0010] Furthermore, in step S3, the coating treatment is as follows: the irradiated fruit is placed in a sterile environment for 10-30 minutes, and a food-grade coating agent is sprayed onto the surface; the food-grade coating agent contains the following raw materials in parts by weight percentage: 0.1-0.5% chitosan, 0.05-0.2% glycerol, and the balance being deionized water.
[0011] Furthermore, the target fruit is a berry, a tropical or subtropical fruit, a pome fruit, or a drupe.
[0012] By adopting the aforementioned technical solution, the beneficial effects of the present invention are as follows: 1. By using high-energy electron beam irradiation, the structure of microorganisms can be efficiently destroyed, achieving thorough sterilization. Simultaneously, combined with a modified atmosphere irradiation environment, the respiration and metabolic rate of the fruit itself are effectively suppressed during the irradiation process. This kills pathogens while reducing the damage to fruit pulp cells caused by free radicals generated by irradiation, avoiding the quality deterioration that might result from simple irradiation.
[0013] 2. Based on the fruit variety, size, and maturity, different irradiation doses are selected according to the storage resistance category. At the same time, the modified atmosphere parameters are adjusted according to the respiration intensity. While ensuring the sterilization effect, the unique flavor and nutritional value of various fruits are preserved to the greatest extent, and the softness or flavor loss caused by excessive irradiation is prevented.
[0014] 3. Through food-grade coating treatment, a semi-permeable protective film is formed on the surface of the fruit. This film effectively locks in moisture, reducing wilting caused by water evaporation, while blocking external oxygen, further inhibiting oxidative browning and respiration. Combined with the previous irradiation and modified atmosphere treatment, the three work synergistically to significantly delay the ripening and senescence process of the fruit, thus achieving a longer storage and shelf life at room temperature.
[0015] 4. High-energy electron beam irradiation combined with modified atmosphere assisted irradiation environment construction and aseptic coating process can be easily integrated with existing fruit post-harvest production lines and is suitable for large-scale application. Attached Figure Description
[0016] Figure 1 These are experimental diagrams illustrating the effects of electron beam irradiation on the quality of postharvest yellow passion fruit in Examples 1 to 5 of this invention. Figure 2These are experimental diagrams illustrating the effects of electron beam irradiation on the surface of postharvest watermelon and guava fruits in Examples 6 to 10 of this invention. Figure 3 These are experimental diagrams illustrating the effects of electron beam irradiation on the interior of postharvest watermelon and guava fruits in Examples 6 to 10 of this invention. Figure 4 These are experimental diagrams illustrating the effects of electron beam irradiation on the quality of post-harvest litchi fruit in Examples 11 to 13 of this invention. Detailed Implementation Example 1
[0017] A method for irradiating and sterilizing fruit includes the following steps: S1. Fruit pretreatment and grading: Select fresh target fruits without serious mechanical damage or pests and diseases, sort and clean them, and grade them according to variety, size and ripeness; the target fruit is yellow passion fruit. S2, High-energy electron beam irradiation treatment: The fruit treated in step S2 is placed on a conveyor belt and irradiated with a high-energy electron beam generated by an electron accelerator; the energy of the high-energy electron beam used for the high-energy electron beam irradiation treatment is 10MeV, and the irradiation dose is selected according to the storage resistance category of the fruit after grading in step S1. Given that yellow passion fruit is a storage-resistant fruit, the irradiation dose is 0.1kGy; The electron beam scanning method is dynamic scanning with a repetition frequency of 41 Hz; the electron beam current intensity is 93 uA; the conveyor belt speed is 167 mm / s; the irradiation environment temperature is controlled at 25℃ and the relative humidity is controlled at 60%. S3. Post-irradiation treatment and storage: After irradiation, the fruit is left to stand for 20 minutes before being coated with a film, and then packaged and stored. The packaging involves individually packaging the coated yellow passion fruit in perforated preservation bags or packing them into appropriate quantities in boxes, and then storing them in a cold storage at a temperature of 5±1℃ and a relative humidity of 90%.
[0018] In step S2, before the high-energy electron beam irradiation treatment, there is also a modified atmosphere-assisted irradiation environment construction step, and the fruit treated in step S1 is placed in the modified atmosphere-assisted irradiation environment for irradiation. The oxygen and carbon dioxide volume concentrations in the modified atmosphere irradiation environment are adjusted according to the respiratory characteristics of the graded fruits: given that yellow passion fruit is a tropical and subtropical fruit with low respiratory intensity, the parameters of the modified atmosphere irradiation environment are set as follows: oxygen volume concentration of 3% and carbon dioxide volume concentration of 7%.
[0019] In step S3, the coating treatment is as follows: the irradiated fruit is placed in a sterile environment for 20 minutes, and then a food-grade coating agent is sprayed onto the surface; the food-grade coating agent contains the following raw materials in parts by weight percentage: 0.3% chitosan, 0.1% glycerol, and the balance being deionized water.
[0020] The storage is a reduced-pressure storage method, with the absolute vacuum pressure controlled at 70 kPa, relative humidity at 95%, and storage temperature at 15°C. Simultaneously, a gas circulation system is activated, controlling the gas circulation flow rate at 1.5 m / s. A mixture of sterile air and modified atmosphere gas is introduced every 2 hours, with an oxygen volume concentration of 5% and a carbon dioxide volume concentration of 8%. Each gas exchange fills 20% of the storage chamber volume to maintain a low-oxygen, suitable carbon dioxide concentration, and stable humidity environment. This synergistically inhibits fruit respiration and microbial growth, extending the shelf life.
[0021] Leave the irradiated fruit for 20 minutes to allow any small amount of volatile byproducts that may have formed to dissipate. Example 2
[0022] The difference from Example 1 is that the high-energy electron beam irradiation dose of Passiflora cuspidatum is 0.2 kGy. Other technical solutions are the same as in Example 1. Example 3
[0023] The difference from Example 1 is that the high-energy electron beam irradiation dose of Passiflora cuspidatum is 0.3 kGy. Other technical solutions are the same as in Example 1. Example 4
[0024] The difference from Example 1 is that the high-energy electron beam irradiation dose of Passiflora cuspidatum is 0.4 kGy. Other technical solutions are the same as in Example 1. Example 5
[0025] The difference from Example 1 is that the high-energy electron beam irradiation dose of Passiflora cuspidatum is 0.5 kGy. All other technical aspects are the same as in Example 1.
[0026] Examples 1 to 5 used post-harvest passion fruit as experimental material. Under varying doses of electron beam irradiation while keeping other experimental conditions constant, a control group (ck) and five irradiation treatment groups (Examples 1 to 5) were set up with irradiation doses of 0.1 kGy, 0.2 kGy, 0.3 kGy, 0.4 kGy, and 0.5 kGy, respectively. Starting from day 0 post-harvest, changes in the appearance of the passion fruit were observed and recorded at regular intervals. Figure 1 As shown, Figure 1 The graph shows the changes in appearance characteristics such as color and shape of the target fruits in Examples 1 to 5 under different irradiation doses compared with the control group.
[0027] Early storage period (0d): The overall color of the fruits in each group was relatively bright, mostly light green, and the appearance was plump. There was no obvious difference between the groups, indicating that the irradiation treatment had not yet caused significant visible changes to the appearance of the fruits, and the fruits were in a fresh initial state.
[0028] Mid-storage (3-6 days): The green color of the fruit in the control group (CK) gradually deepened and darkened, with some fruits showing uneven coloring and a slight decrease in plumpness. The rate of color darkening and fading slowed down in each irradiation dose group, and the appearance remained relatively plumper. There were also slight differences between the different dose groups. The lower dose groups (e.g., 0.1 kGy, 0.2 kGy) performed slightly better than the higher dose groups (e.g., 0.4 kGy, 0.5 kGy) in terms of color retention and plumpness maintenance, but overall, they all appeared fresher than the control group.
[0029] During the later stages of storage (9-15 days): the fruit in the control group (CK) showed a significant darkening in color, with many exhibiting a yellowish-brown or even dark hue. The fruit was noticeably wrinkled and shriveled, with a high degree of softening and deterioration in quality. As storage time increased, while the fruit in each irradiation dose group also gradually showed darkening in color and wrinkling, the deterioration process was significantly slower compared to the control group. The low-dose irradiation groups (e.g., 0.1 kGy, 0.2 kGy) exhibited relatively brighter fruit color and the least wrinkling throughout the storage period. As the irradiation dose increased to 0.3 kGy and above, the fruit showed a certain downward trend in plumpness and color brightness, but remained far superior to the control group. Example 6
[0030] A method for irradiating and sterilizing fruit includes the following steps: S1. Select fresh target fruits without serious mechanical damage or pests and diseases, sort and wash them, and grade them according to variety, size and ripeness; the target fruits are watermelon red guava. S2, High-energy electron beam irradiation treatment: The fruit treated in step S2 is placed on a conveyor belt and irradiated with a high-energy electron beam generated by an electron accelerator; the energy of the high-energy electron beam used for the high-energy electron beam irradiation treatment is 10MeV, and the irradiation dose is selected according to the storage resistance category of the fruit after grading in step S1. Since watermelon and red guava are storage-resistant fruits, the irradiation dose is 0.1kGy. The electron beam scanning method is dynamic scanning with a repetition frequency of 41 Hz; the electron beam current intensity is 93 uA; the conveyor belt speed is 167 mm / s; the irradiation environment temperature is controlled at 25℃ and the relative humidity is controlled at 40%. S3. Apply a coating to the irradiated fruit, then package and store it.
[0031] In step S2, before the high-energy electron beam irradiation treatment, there is also a modified atmosphere-assisted irradiation environment construction step, and the fruit treated in step S1 is placed in the modified atmosphere-assisted irradiation environment for irradiation. The oxygen and carbon dioxide volume concentrations in the modified atmosphere irradiation environment are adjusted according to the respiratory characteristics of the graded fruits. Given that watermelon and guava are tropical and subtropical fruits with low respiratory intensity, the parameters of the modified atmosphere irradiation environment are set as follows: oxygen volume concentration of 2.5% and carbon dioxide volume concentration of 4%.
[0032] In step S2, the energy of the high-energy electron beam used for high-energy electron beam irradiation is 10 MeV. The irradiation dose is selected according to the storage resistance category of the fruit after grading in step S1. Given that watermelon and guava are storage-resistant fruits, the irradiation dose is 0.1 kGy.
[0033] In step S3, the coating treatment is as follows: the irradiated fruit is placed in a sterile environment for 20 minutes, and then a food-grade coating agent is sprayed onto the surface; the food-grade coating agent contains the following raw materials in parts by weight percentage: 0.3% chitosan, 0.1% glycerol, and the balance being deionized water.
[0034] The storage is a reduced-pressure storage method, with the absolute vacuum pressure controlled at 50 kPa, relative humidity at 85%, and storage temperature at 10°C. Simultaneously, a gas circulation system is activated, controlling the gas circulation flow rate at 1.0 m / s. A mixture of sterile air and modified atmosphere gas is introduced every 2 hours, with an oxygen volume concentration of 3% and a carbon dioxide volume concentration of 5%. Each gas exchange fills 20% of the storage chamber volume to maintain a low-oxygen, suitable carbon dioxide concentration, and stable humidity environment. This synergistically inhibits fruit respiration and microbial growth, extending the shelf life. Example 7
[0035] The difference from Example 6 is that the high-energy electron beam irradiation dose of the watermelon guava is 0.2 kGy. All other technical aspects are the same as in Example 6. Example 8
[0036] The difference from Example 6 is that the high-energy electron beam irradiation dose of the watermelon guava is 0.3 kGy. All other technical aspects are the same as in Example 6. Example 9
[0037] The difference from Example 6 is that the high-energy electron beam irradiation dose of the watermelon guava is 0.4 kGy. All other technical aspects are the same as in Example 6. Example 10
[0038] The difference from Example 6 is that the high-energy electron beam irradiation dose of the watermelon guava is 0.5 kGy. All other technical aspects are the same as in Example 6.
[0039] Examples 6 to 10 used post-harvest watermelon guava fruits as experimental materials. Under the condition of varying electron beam irradiation doses while keeping other experimental conditions constant, a control group (ck) and five irradiation treatment groups (Examples 6 to 10) were set up, with irradiation doses of 0.1 kGy, 0.2 kGy, 0.3 kGy, 0.4 kGy, and 0.5 kGy, respectively. Starting from day 0 post-harvest, the changes in the appearance of the watermelon guava fruits were observed and recorded at regular intervals. Figure 2 As shown, Figure 2 The graphs show the changes in color, appearance, and other appearance characteristics of the target fruits in Examples 6 to 10 under different irradiation doses compared to the control group.
[0040] In the blank control group (ck), the fruit surface color gradually changed from bright green to yellowish-green as the storage time increased, and obvious signs of aging or rotting such as browning and softening appeared in the later stage. The appearance of the fruit in the different irradiation dose treatment groups (0.1kGy-0.5kGy) at each storage time point differed from that of the blank group: the low dose (e.g., 0.1kGy) treatment had a certain effect on maintaining the color of the fruit in the early stage, but as the storage days increased, the fruit also showed different degrees of color change and aging. In the medium and high dose (e.g., 0.2kGy and above) treatment groups, the fruit surface was relatively greener and the aging process was delayed in the early stage of storage (e.g., 2-4 days), but when the dose reached 0.4kGy and 0.5kGy, obvious fruit deterioration (e.g., dark skin, local soft rot, etc.) also appeared in the later stage (e.g., 8-10 days).
[0041] Figure 3 These are experimental diagrams illustrating the effects of electron beam irradiation on the interior of postharvest watermelon red guava fruits in Examples 6 to 10 of this invention. Through visualization of the guava's appearance and pulp condition, the effects of irradiation treatment on delaying fruit senescence and maintaining fruit quality are compared and analyzed: From top to bottom, the first and second rows show the changes in the overall appearance of the guava fruit. It can be observed that as storage time increases, the control group's fruit gradually shows signs of darkening in color, rotting, or softening, while the fruit in the 0.3 kGy irradiation treatment group is significantly better than the control group in terms of appearance integrity and color retention; the third row shows the cross-sectional state of the guava pulp, clearly demonstrating that the control group's pulp is prone to softening, rotting, and discoloration in the later stages of storage. In contrast, the pulp in the irradiation treatment group maintains good firmness and color for a longer period, demonstrating that electron beam irradiation has a good preservation effect on the quality of postharvest watermelon red guava fruits. Example 11
[0042] A method for irradiating and sterilizing fruit includes the following steps: S1. Select fresh target fruits without serious mechanical damage or pests and diseases, sort and wash them, and grade them according to variety, size and ripeness; the target fruit is lychee; S2, High-energy electron beam irradiation treatment: The fruit treated in step S2 is placed on a conveyor belt and irradiated with a high-energy electron beam generated by an electron accelerator; the energy of the high-energy electron beam used for the high-energy electron beam irradiation treatment is 10MeV, and the irradiation dose is selected according to the storage resistance category of the fruit after grading in step S1. Since lychee is a perishable fruit, the irradiation dose is 1.0kGy. The electron beam scanning method is dynamic scanning with a repetition frequency of 151 Hz; the electron beam current intensity is 910 uA; the conveyor belt speed is 163 mm / s; the irradiation environment temperature is controlled at 5℃ and the relative humidity is controlled at 80%. S3. Apply a coating to the irradiated fruit, then package and store it.
[0043] In step S2, before the high-energy electron beam irradiation treatment, there is also a modified atmosphere-assisted irradiation environment construction step, and the fruit treated in step S1 is placed in the modified atmosphere-assisted irradiation environment for irradiation. The oxygen and carbon dioxide volume concentrations in the modified atmosphere irradiation environment are adjusted according to the respiratory characteristics of the graded fruits. Given that lychees are perishable fruits with high respiratory intensity, the parameters of the modified atmosphere irradiation environment are set as follows: oxygen volume concentration of 3.5% and carbon dioxide volume concentration of 6%.
[0044] In step S2, the energy of the high-energy electron beam used for high-energy electron beam irradiation is 10 MeV. The irradiation dose is selected according to the storage resistance category of the fruit after grading in step S1. Given that lychee is a perishable fruit, the irradiation dose is 1.0 kGy.
[0045] In step S3, the coating treatment is as follows: the irradiated fruit is placed in a sterile environment for 20 minutes, and then a food-grade coating agent is sprayed onto the surface; the food-grade coating agent contains the following raw materials in parts by weight percentage: 0.3% chitosan, 0.1% glycerol, and the balance being deionized water.
[0046] The storage is a reduced-pressure storage method, with the absolute vacuum pressure controlled at 60 kPa, relative humidity at 90%, and storage temperature at 10°C. Simultaneously, a gas circulation system is activated, controlling the gas circulation flow rate at 1.2 m / s. A mixture of sterile air and modified atmosphere gas is introduced every 2 hours, with an oxygen volume concentration of 4% and a carbon dioxide volume concentration of 6%. Each gas exchange fills 20% of the storage chamber volume to maintain a low-oxygen, suitable carbon dioxide concentration, and stable humidity environment. This synergistically inhibits fruit respiration and microbial growth, extending the shelf life. Example 12
[0047] The difference from Example 11 is that the high-energy electron beam irradiation dose of the lychee is 1.2 kGy. Other technical solutions are the same as in Example 11. Example 13
[0048] The difference from Example 11 is that the high-energy electron beam irradiation dose of the lychee is 1.5 kGy. Other technical solutions are the same as in Example 11.
[0049] Examples 11 to 13 used post-harvest litchi fruits as experimental materials. Under the condition of varying electron beam irradiation doses while keeping other experimental conditions constant, a control group (ck) and three irradiation treatment groups (Examples 11 to 13) were set up, with irradiation doses of 1.0 kGy, 1.2 kGy, and 1.5 kGy, respectively. Starting from day 0 post-harvest, changes in the appearance of the litchi fruits were observed and recorded at regular intervals. Figure 4 As shown, Figure 4 These are experimental diagrams illustrating the effects of electron beam irradiation on the quality of post-harvest litchi fruit in Examples 11 to 13 of this invention.
[0050] As the storage time increased, the litchi fruits in each group showed varying degrees of regional changes in color and texture. The control group (ck) fruits showed browning and softening earlier, while the 1kGy, 1.2kGy, and 1.5kGy irradiation treatment groups maintained better freshness and color during the same storage period. There were also some differences among the different irradiation doses, reflecting the effect of electron beam irradiation on delaying the post-harvest quality deterioration of litchi and the dose-response relationship.
[0051] Comparative Example 1 The difference from Example 11 is that in step S3, instead of pressure-reduced storage, atmospheric pressure cold storage is used, with a temperature of 5±1℃ and a relative humidity of 90%, without gas circulation or introduction of mixed gas. Other technical solutions are the same as in Example 11.
[0052] Comparative Example 2 The difference from Example 11 is that high-energy electron beam irradiation is not performed in step S2. All other technical solutions are the same as in Example 11.
[0053] Comparative Example 3 The difference from Example 11 is that no pretreatment, electron beam irradiation treatment, or depressurization treatment is performed. Fresh lychees are directly stored in a cold storage at normal pressure with a temperature of 5±1℃ and a relative humidity of 90%.
[0054] Table 1 Group Total bacterial count (CFU / g) Mold and yeast (CFU / g) Coliform bacteria (MPN / g) Rot rate (%) Example 11 <5 5 <1 2.5 Comparative Example 1 <![CDATA[1×10 3 ]]> <![CDATA[2×10 4 ]]> 10 7 Comparative Example 2 <![CDATA[8×10 4 ]]> <![CDATA[5×10 5 ]]> 800 15 Comparative Example 3 (Control Group) <![CDATA[>10 5 ]]> <![CDATA[8×10 6 ]]> >1100 12.4 This invention employs a multi-technology synergistic approach combining low-dose high-energy electron beam irradiation with depressurized storage and modified atmosphere assisted environment construction. This approach can effectively inhibit / kill microorganisms, pests, and their enzyme activity in fruits. Through the strong synergistic effect of "precise electron beam sterilization + depressurized modified atmosphere post-sterilization," it significantly extends the shelf life and achieves quarantine and pest control objectives. Furthermore, in actual production, it eliminates the need to damage fruit packaging, supports continuous high-throughput conveyor belt operations, is easy to operate, and is compatible with existing cold chain systems. This provides an efficient and integrated solution for post-harvest loss reduction and international trade quarantine of fruits.
[0055] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.
Claims
1. A method for irradiating and sterilizing fruit, characterized in that, Includes the following steps: S1. Fruit pretreatment and grading: Select fresh target fruits without serious mechanical damage or pests and diseases, sort and clean them, and grade them according to variety, size and ripeness. S2. High-energy electron beam irradiation treatment: The fruit treated in step S1 is placed on a conveyor belt and irradiated with a high-energy electron beam generated by an electron accelerator. The energy of the high-energy electron beam used for irradiation treatment is 10 MeV. The irradiation dose is selected according to the storage resistance category of the fruit after grading in step S1: the irradiation dose for perishable fruits is 1.0-1.5 kGy, and the irradiation dose for storage-resistant fruits is 0.1-0.5 kGy. S3. Post-irradiation treatment and storage: The irradiated fruit is coated with a film, then packaged and stored.
2. The method for irradiating and sterilizing fruit according to claim 1, characterized in that, The electron beam scanning method is dynamic scanning with a repetition frequency of 5-581Hz; the electron beam current intensity is 0-2mA; the conveyor belt speed is 20mm / s-180mm / s; the irradiation environment temperature is controlled at 20-35℃ and the relative humidity is controlled at 40-80%.
3. The method for irradiating and sterilizing fruit according to claim 1, characterized in that, In step S2, before the high-energy electron beam irradiation treatment, there is also a modified atmosphere-assisted irradiation environment construction step, and the fruit treated in step S1 is placed in the modified atmosphere-assisted irradiation environment for irradiation. The oxygen and carbon dioxide volume concentrations in the modified atmosphere irradiation environment are adjusted according to the respiratory characteristics of the graded fruits: for perishable fruits with high respiratory intensity, the oxygen volume concentration is set at 3-5% and the carbon dioxide volume concentration at 5-10%; for tropical and subtropical fruits with low respiratory intensity, the oxygen volume concentration is set at 2-4% and the carbon dioxide volume concentration at 3-8%.
4. The method for irradiating and sterilizing fruit according to claim 1, characterized in that, In step S3, the coating treatment is as follows: the irradiated fruit is placed in a sterile environment for 10-30 minutes, and a food-grade coating agent is sprayed onto the surface; the food-grade coating agent contains the following raw materials in parts by weight percentage: 0.1-0.5% chitosan, 0.05-0.2% glycerol, and the balance is deionized water.
5. The method for irradiating and sterilizing fruit according to claim 1, characterized in that, The target fruits are berries, tropical and subtropical fruits, pome fruits, or drupes.