Photoperiod fresh-keeping method for improving fresh-keeping quality of picked strawberries

Abstract

The invention relates to the technical field of biology, in particular to a photoperiod fresh-keeping method for improving the fresh-keeping quality of picked strawberries, which comprises the following steps of: performing illumination for 12-16 hours in a photoperiod of 24 hours and darkness in other time when strawberry fruits are refrigerated and preserved. Experiments prove that compared with continuous darkness and continuous illumination used in traditional strawberry preservation, the shelf life of the Xiangwild strawberries and the light snow strawberries can be remarkably prolonged under the premise that the quality and the edible safety of the strawberries are not influenced by preservation under the condition of a specific photoperiod. The invention discloses a photoperiod condition for preserving Xiangwild strawberries and a photoperiod condition for preserving light snow strawberries. The method provided by the invention is low in cost and easy to operate, is suitable for common families, can also be applied to strawberry production, transportation and retail industries on a large scale, and has important application value.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and in particular relates to a photoperiod preservation method for improving the post-harvest fresh-keeping quality of strawberries. Background Art

[0002] Strawberries are sweet and rich in nutrients, making them popular among consumers. However, due to limited planting areas and a large amount of post-harvest losses and waste, the current strawberry market is in short supply, and the prices of some strawberry varieties have remained high for a long time. Strawberry quality and storage and transportation costs are the main factors affecting strawberry prices. The pale snow strawberry is native to Japan and is a typical "strawberry luxury". Although it has a white and red appearance and a sweeter taste, its overall hardness is low and it is extremely difficult to store and transport, so its price is extremely high. The traditional-looking Xiangye strawberry is less sweet than the pale snow strawberry, but it has high hardness, is resistant to storage and transportation, and has a more affordable price. These two types of strawberries represent the two typical types of strawberry storage and transportation qualities on the market, and also correspond to the short and long shelf lives of strawberries. A long shelf life not only gives strawberry practitioners time to transport strawberries and reduce intermediate costs; it also gives retailers buffer time and reduces storage losses. Therefore, the length of the shelf life is the key to adjusting the price of strawberries.

[0003] Currently, the mainstream method of preserving strawberries is to store them at low temperatures under conditions of continuous darkness or continuous light. Although this method is easy to operate, it still has many shortcomings that need to be improved. For example: low temperature inhibits all physiological activities of post-harvest strawberries, which may affect their taste, appearance and other qualities; low temperature will not change the insect and disease resistance of the strawberries themselves, but only reduce the vitality of pathogens and pests. This shows that strawberry preservation cannot rely solely on traditional low-temperature methods, but also needs to develop more effective and low-energy methods as a supplement.

[0004] In recent years, some new methods of strawberry preservation have been reported one after another. For example: storing strawberries at ultra-low temperatures below zero; adding chemical coatings for preservation; strawberry conditioning and ultraviolet irradiation preservation. Compared with traditional low-temperature storage, these technologies can significantly extend the shelf life of strawberries. However, the loss of strawberry taste and nutrients, the high cost of equipment and instruments, and the difficulty of operation have limited the use of these technologies.

[0005] As a simple physical factor, light has been shown to have a significant effect on the insect resistance of blueberry and cabbage leaves in storage. Changing the biological clock of fruits and vegetables during storage by photoperiod can not only artificially intervene in the physiological state and gene expression of fruits and vegetables, but also does not introduce other elements, is environmentally friendly, low-carbon and pollution-free. Compared with the currently reported strawberry preservation methods, the method of using photoperiod to change the physiological state of strawberries and thus extend the shelf life is easier to operate and has higher application potential and value. However, no suitable photoperiod conditions have been screened for strawberries, so the shelf life of strawberries cannot be extended by changing the photoperiod conditions. Summary of the invention

[0006] In view of the above technical status, a photoperiod preservation method for improving the post-harvest fresh-keeping quality of strawberries is provided.

[0007] The invention provides a photoperiodic preservation method for improving the post-harvest preservation quality of strawberries, which specifically comprises the steps of irradiating the strawberries with light for 12 to 16 hours in a photoperiod of 24 hours and keeping them dark for the rest of the time when the strawberries are stored in cold storage.

[0008] In the above method, when the strawberry variety is Xiangye, the light can be any one of white light, red light and blue light.

[0009] In the above method, when the strawberry variety is Xiangye, the duration of illumination in each 24-hour photoperiod is preferably 16 hours.

[0010] In the above method, when the strawberry variety is Xiangye, the start time of the photoperiod is ZT0, and the start time of illumination is at least 8 hours from ZT0.

[0011] In the above method, when the strawberry variety is Xiangye, the best photoperiod preservation method is to use any one of white light, red light, and blue light for illumination, the illumination duration is 16 hours, the start time of the subjective photoperiod is ZT0, and the start time of illumination is at least 8 hours from ZT0.

[0012] In the above method, when the strawberry variety is light snow, the lighting adopts white light.

[0013] In the above method, when the strawberry variety is light snow, the duration of illumination in each 24-hour photoperiod is preferably 12 hours.

[0014] In the above method, when the strawberry variety is light snow, the start time of the photoperiod is ZT0, and the start time of illumination is 4-12 hours from ZT0.

[0015] In the above method, when the strawberry variety is light snow, the best photoperiod preservation method is to use white light for illumination, the illumination duration is 12 hours, the start time of the photoperiod is ZT0, and the start time of illumination is 4-12 hours from ZT0.

[0016] In the above method, the refrigeration temperature is 4°C.

[0017] The present application screened the preservation effects of light color, light cycle, light length and light application time on Xiangye and Danxue strawberries, and obtained the optimal lighting conditions that can extend the shelf life of Xiangye and Danxue strawberries. In order to illustrate its practicality from multiple angles, the applicant not only conducted a statistical analysis on the appearance of strawberries under the light conditions, but also tested the hardness closely related to the storage and transportation of strawberries, the sugar-acid ratio SAR (Sugar to titratable acidity ratio) closely related to the taste of strawberries, and ochratoxin A related to food safety. Compared with strawberries stored at low temperatures under traditional continuous darkness or continuous light conditions, the screened light cycle conditions can not only significantly improve the appearance quality of Xiangye and Danxue strawberries during the preservation period, but also have no significant effect on their hardness and taste. The detection of mycotoxins also shows that the method is food safety. It can be seen that the use of light cycle technology is low-cost, simple and easy to operate, suitable for ordinary household use, and can also be used on a large scale in the storage and transportation of the strawberry industry. The present invention has important application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 To screen the optimal storage light conditions for Fragrant Wild Strawberry and Light Snow Strawberry. Figure 1 (a) is the photoperiod setting, where LL is continuous light, DD is continuous darkness, LD is 16 hours of light followed by 8 hours of darkness; DL is 8 hours of darkness followed by 16 hours of light, and ZT refers to subjective time. The start time of the subjective photoperiod is ZT0, 4 hours from ZT0 is ZT4, 8 hours from ZT0 is ZT8, and 12 hours from ZT0 is ZT12. Figure 1 (b) is the setting of light color.

[0019] Figure 2 The appearance changes of Fragrant Wild Strawberry and Light Snow Strawberry when stored under different light conditions.

[0020] Figure 3 The quality changes of Fragrant Wild Strawberry and Light Snow Strawberry under different photoperiod conditions. The data shown in the figure are mean ± standard deviation, with 3 replicates. The significant differences among the groups were analyzed by one-way ANOVA. Different lowercase letters after each treatment indicate significant differences among the treatments.

[0021] Figure 4The quality changes of Fragrant Wild Strawberry and Light Snow Strawberry under red, blue and white storage conditions. The data shown in the figure are mean ± standard deviation, with 3 replicates. The significant differences among the groups were analyzed by one-way ANOVA. Different lowercase letters after each treatment indicate significant differences among the treatments.

[0022] Figure 5 The quality changes of Xiangye strawberry and Danxue strawberry under 4 hours, 8 hours and 16 hours of light duration. The data shown in the figure are mean ± standard deviation, with 3 replicates. The significant differences among the groups were analyzed by one-way ANOVA. Different lowercase letters after each treatment indicate significant differences among the treatments.

[0023] Figure 6 The quality changes of Xiangye strawberry under light treatment at ZT4 and ZT8, and Danxue strawberry under light treatment at ZT4, ZT8 and ZT12. The data shown in the figure are mean ± standard deviation, with 3 replicates, and the significant differences among the groups were analyzed by one-way ANOVA. Different lowercase letters after each treatment indicate significant differences among the treatments. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0025] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0026] Example 1 1. Strawberry materials and detection methods Mature wild strawberries and snow strawberries are both commercial strawberry varieties, picked in Beijing and grown in greenhouses. Immediately after picking, they were stored in an environment with different light conditions at 4°C. Samples were taken on the first, fifth, tenth, and fifteenth days of storage, and every three strawberries were mixed into one sample. A total of three samples were collected as three biological replicates and tested as follows: 1.1 Appearance record of strawberry during its freshness period and prediction of its shelf life (1) Take photos of the strawberries on the 1st, 5th, 10th and 15th days of storage. Evaluate the appearance of the strawberries and record the scores according to Table 1 (reference: Anastasia Ktenioudaki., et al., Modelling the biochemical and sensory changes of strawberries during storage under diverse relative humidity conditions. Postharvest Biology and Technology, 2019.154(4): p.148-158.).

[0027] Table 1. Strawberry fruit appearance scoring table Score Fruit appearance characteristics 1 95% no obvious color change, good gloss, no damage or disease 2 Slightly dark spots appear, the fruit surface has some soft tissue, but the gloss is good 3 >50% of the surface has dark red spots, slight shrinkage and softening of tissue, but is shiny 4 >50% of the fruit surface has dark red spots, slight shrinkage and softening of the tissue, some of the fruit skin is damaged and the surface loses its luster 5 The surface is dull and has no damage, or the surface of the fruit has lost some of its luster and has obvious tissue damage 6 The surface is dull and damaged, with softened and water-soaked tissue 7 Visible spots appear on the fruit surface 8 A large number of plaques or hyphae appear on the surface of the fruit 9 Complete rot of fruit tissue (2) Linear regression fitting was performed with time as the variable and the appearance scores of Xiangye strawberry and Danxue strawberry as the dependent variable. The score of 2.5 was taken as the critical point. Scores above 2.5 were not accepted by consumers. The shelf life of strawberries was predicted.

[0028] (3) The shelf life data were statistically analyzed using one-way analysis of variance.

[0029] 1.2 Strawberry quality determination The hardness of strawberries is an important factor related to the storage and transportation of strawberries. Low hardness of strawberries will cause them to be easily damaged during storage and transportation; and the sugar-acid ratio of strawberries will affect the taste of strawberries. These two indicators will directly affect consumers' consumption perception. In addition, strawberries will become moldy and rotten during storage and transportation. In addition to the visible hyphae, the detection of fungal toxins is related to the food safety of strawberries. The fungal toxin that is often contained in strawberries and has clear international limit standards is ochratoxin, which is classified as a Class 2B carcinogen.

[0030] The specific steps are as follows: (1) Strawberry hardness test. After cutting the shoulder of the strawberry fruit, slowly press the hardness tester (GY-2 fruit hardness tester, JINKOLIDA) vertically into the flesh until the scale line is immersed in the flesh, and record the stable hardness reading. The average value of the strawberry hardness on the first day was used as the standard to obtain the hardness change of the strawberry on the 5th, 10th and 15th days relative to the first day. The data on the change of strawberry hardness were statistically tested using a two-way analysis of variance.

[0031] (2) SAR detection of strawberries. The total sugar of strawberries was detected using the Total Sugar and Reducing Sugar Detection Kit (Leagene, TC0698) in a reduced dosage according to the instructions. The titratable acid of strawberries was detected using the Titratable Acid (TA) Detection Kit (Leagene, TC2303-50T) in a reduced dosage according to the instructions. The total sugar and titratable acid were standardized according to the total amount of strawberry samples. SAR can be obtained by the standardized total sugar / standardized titratable acid of the same strawberry sample. The average value of the strawberry SAR on the first day was used for standardization to obtain the change in firmness of the strawberries on the 5th, 10th and 15th days relative to the first day. The data on the change in strawberry firmness were statistically tested using a two-way analysis of variance.

[0032] (3) Detection of ochratoxin A in strawberries. Ochratoxin A detection card colloidal gold method (D-Chem, OTA-1-50) was used according to the instructions, and the sample detection concentration was increased by 20 times to detect ochratoxin A in strawberry samples.

[0033] 2. Lighting condition settings and test results For the optimal storage light conditions for selecting Fragrant Wild Strawberries and Light Snow Strawberries, please refer to the attached Figure 1 , the lighting conditions and related test conclusions are as follows: 2.1 Preliminary screening of photoperiod conditions First, set a rough light cycle to confirm its preservation effect. The conditions of continuous light (LL) and continuous darkness (DD) were set to simulate the lighting conditions of fruit sales refrigerators and household refrigerators respectively; the condition of 16 hours of light followed by 8 hours of darkness (LD) was set to simulate the light cycle of the normal growth environment of strawberries; the condition of 8 hours of darkness followed by 16 hours of light (DL) was set to simulate the lighting conditions in cross-time zone transportation scenarios. Among them, ZT (Zeitgeber Time) refers to subjective time, such as ZT0 refers to the beginning of a subjective light cycle, that is, the 0th hour, and ZT8 refers to the 8th hour of a subjective light cycle (see Figure 1 (a)).

[0034] After picking, they were immediately stored at 4°C. White light (LED lamp, manufacturer: mexce, power: 4 W) was used as the light source under four photoperiod conditions. Sampling was carried out on the 1st, 5th, 10th and 15th days of storage. Every 3 strawberries were mixed into one sample, and a total of 3 samples were collected as 3 biological replicates for testing.

[0035] The appearance of Fragrant Wild Strawberry and Light Snow Strawberry was recorded on the 1st, 5th, 10th and 15th day of storage (see the results in Figure 2 (a)), and calculate the change of its quality with respect to time (see Figure 3 (a)). Since the strawberry has good appearance quality and glossy at 2 points, and obvious dark red spots appear at 3 points, we set 2.5 points as the critical point acceptable to consumers and make shelf life predictions. The prediction results are shown in the figure. Figure 3 (b). Statistical analysis showed that the DL condition could significantly extend the shelf life of Xiangye strawberry, which was about 3.2 days longer than the shortest shelf life DD condition; while for Danxue strawberry, the DL condition still had a longer shelf life than the DD condition, but due to its low hardness, the DL condition did not significantly extend the shelf life compared to the LL and LD conditions.

[0036] Further testing of the preservation quality of Xiangye strawberry and Danxue strawberry showed that the DL condition did not significantly affect the SAR and firmness of the strawberry (see Figure 3 In addition, the results of ochratoxin A test indicated that the wild strawberry stored under DL conditions was food safe (see Figure 3 The above results show that DL can prolong the shelf life of Fragrant Wild Strawberry and Light Snow Strawberry without affecting the quality of strawberry, and has the potential and value for promotion and application.

[0037] Therefore, DL conditions can prolong the shelf life of Fragrant Wild Strawberry and Light Snow Strawberry, and the DL condition of 8 hours of darkness followed by 16 hours of light was used as the preliminary screened photoperiod type.

[0038] 2.2 Light color screening After the initial photoperiod type was determined as DL in 2.1, the white light was changed to different light colors for preservation experiments to determine the light color type that is most conducive to the storage of Xiangye strawberry and Danxue strawberry (see Figure 1 In (b), the wavelength of the visible red light used in this embodiment is 630-680 nm, and the wavelength of the visible blue light is 450-470 nm.

[0039] Strawberries were immediately stored at 4°C after picking. Under the DL light cycle, blue light (LED lamp, manufacturer: Zhongshan Ou Ri Lighting Co., Ltd.) and red light (LED lamp, manufacturer: Zhongshan Ou Ri Lighting Co., Ltd.) were used as light sources instead of white light. Sampling was carried out on the 1st, 5th, 10th and 15th days of storage, and every 3 strawberries were mixed into one sample. A total of 3 samples were collected as 3 biological replicates for testing.

[0040] Save the result according to appearance (see Figure 2 (b) Predict shelf life. Figure 4(a) The results showed that red light, blue light and white light had no significant effect on the shelf life of wild strawberries, while white light was more conducive to the preservation of snow strawberries than red and blue light.

[0041] The preservation quality of wild strawberry and snow strawberry was measured. The results showed that red light, blue light and white light did not significantly affect the SAR and hardness of wild strawberry. Although the SAR of snow strawberry had no significant difference under red, blue and white light, its hardness was significantly higher under white light than that under red and blue light (see Figure 4 In addition, the results of ochratoxin A test showed that the wild strawberries stored under red light, blue light and white light were food safe (see Figure 4 Middle (d) and Figure 3 In (e), the strawberry stored under white light is food safe (see Figure 5 in (d).

[0042] The above results show that the preservation effect of Fragrant Wild Strawberry in DL under red, blue and white light conditions can be better; while for Danxue Strawberry, the preservation effect of red and blue light is slightly worse than that of DL under white light conditions.

[0043] 2.3 Screening of light duration In order to further reduce energy consumption, the duration of illumination was optimized to determine the low-energy duration that is most conducive to preserving the freshness of Xiangye strawberries and Danxue strawberries. Figure 1 Middle (c): Strawberries of both varieties were immediately stored at 4°C after picking, with white light as the light source (LED tube, manufacturer: mexce, power: 4W), the light cycle was dark first and then light, and the light duration of each light cycle was set to 4 hours, 8 hours, 12 hours and 16 hours. Samples were taken on the 1st, 5th, 10th and 15th days of storage for each variety and each light duration treatment, and every 3 strawberries were mixed into one sample, and a total of 3 samples were collected as 3 biological replicates for testing.

[0044] See the photos of fragrant wild strawberries on days 1, 5, 10 and 15. Figure 2 In (c), the shelf life prediction results are shown in Figure 5 (a) shows that the shelf life of wild strawberries is longer under the conditions of 4 hours, 8 hours and 16 hours of light. However, 4 hours and 16 hours of light are more conducive to the firmness of wild strawberries (see Figure 5 (c)); 8 hours, 12 hours and 16 hours of light can keep the SAR of Fragaria sinensis better (see Figure 5 The wild strawberries grown under 16-hour light conditions were tested for ochratoxin A, and the wild strawberries grown under this condition were food safe (see Figure 3In summary, 16 hours of light conditions are more conducive to the preservation of wild strawberries.

[0045] See the photos of the strawberries on the 1st, 5th, 10th and 15th days. Figure 2 In (c), the shelf life prediction results (see Figure 5 (a) shows that the shelf life of the light snow strawberry has no significant difference under the conditions of 4 hours, 8 hours, 12 hours and 16 hours of light exposure, and its hardness retention and SAR have no significant difference under the four light exposure conditions (see Figure 5 However, since the average properties of the strawberry under 12-hour light conditions were the best and its shelf life was significantly longer than that under 4-hour light conditions, this condition was selected for further optimization. Ochratoxin A was tested in the strawberry, and the strawberry stored under 12-hour light conditions was food safe (see Figure 5 In summary, 12 hours of light conditions are more conducive to the preservation of Danxue strawberry.

[0046] 2.4 Screening of illumination time points The two varieties of strawberries were immediately stored at 4°C after picking, with white light as the light source (LED lamp tube, manufacturer: mexce, power: 4W). The illumination duration of each photocycle for Xiangye strawberry was 16 hours, and the start time of illumination was set to ZT4 and ZT8 (the start time of the subjective photocycle (where ZT (Zeitgeber Time) refers to subjective time, such as ZT0 refers to the beginning of a subjective photocycle, that is, the 0th hour, and ZT8 refers to the 8th hour of a subjective photocycle) was ZT0, 4 hours after ZT0 was ZT4, and 8 hours after ZT0 was ZT8). The illumination duration of each photocycle for Danxue strawberry was 12 hours, and the start time of illumination was set to ZT4, ZT8 and ZT12 (the start time of the subjective photocycle was ZT0, 4 hours after ZT0 was ZT4, 8 hours after ZT0 was ZT8, and 12 hours after ZT0 was ZT12).

[0047] For each variety and each light exposure time point, samples were taken on the 1st, 5th, 10th and 15th days of storage. Every 3 strawberries were mixed into one sample, and a total of 3 samples were collected as 3 biological replicates for testing.

[0048] See the picture of the fruit of the fragrant wild strawberry with 16 hours of light at ZT4. Figure 2 In (d), the shelf life prediction results are shown in Figure 6 (a) shows that applying light at ZT8 can significantly extend the shelf life of fragrant wild strawberries compared to applying light at ZT4. Although applying light at ZT4 and ZT8 had no significant effect on the firmness of fragrant wild strawberries (see Figure 6(c)); however, applying light at ZT8 is more conducive to maintaining the SAR of Fragrant Wild Strawberry (see Figure 6 The wild strawberries grown under ZT8 lighting conditions were tested for ochratoxin A, and the wild strawberries grown under these conditions were food safe (see Figure 3 In summary, applying 16 hours of light at ZT8 is more conducive to the preservation of Xiangye strawberry.

[0049] See the photos of strawberry with 12 hours of light at ZT4, ZT8 and ZT12. Figure 2 The shelf life prediction results are shown in Figure 6 In (a), there is no significant difference in the shelf life of the strawberry with three different light exposure times. In addition, applying light at ZT4, ZT8, and ZT12 had no significant effect on the firmness of the strawberry (see Figure 6 middle (c)); no significant effect on the maintenance of SAR of strawberry (see Figure 6 The strawberries grown under the three conditions were tested for ochratoxin A, and the strawberries grown under these conditions were found to be food safe (the results of ZT12 treatment are shown in Figure 6 Middle (d), results of ZT4 and ZT8 treatments Figure 5 In summary, applying light at ZT4, ZT8, and ZT12 had no significant effect on the shelf life of Dalxue strawberry.

[0050] The above results show that by applying light under different conditions, the shelf life of Xiangye strawberry and Danxue strawberry can be extended on the basis of the existing low-temperature preservation effect, and the quality of strawberry during the preservation period can be improved. Specifically, applying 16 hours of white light (red light / blue light) at ZT8 is most conducive to the preservation of Xiangye strawberry; while applying 12 hours of white light at ZT4, ZT8 and ZT12 is most conducive to the preservation of Danxue strawberry.

[0051] The present invention has been described in detail above. It will be apparent to those skilled in the art that the present invention may be implemented in a wide range under equivalent parameters, concentrations and conditions without departing from the spirit and scope of the present invention and without the need for unnecessary experimentation. Although the present invention provides specific embodiments, it should be understood that further improvements may be made to the present invention. In short, according to the principles of the present invention, this application intends to include any changes, uses or improvements to the present invention, including changes made by conventional techniques known in the art that depart from the scope disclosed in this application. Applications of some of the basic features may be made within the scope of the following appended claims.

Claims

1. A photoperiodic preservation method for improving the post-harvest quality of strawberries, characterized in that: The method comprises the steps of providing 12 to 16 hours of light and the rest of the time in darkness according to a photoperiod of 24 hours when storing strawberry fruits in a cold storage.

2. The method according to claim 1, characterized in that: When the variety of the strawberry is Xiangye, the lighting adopts any one of white light, red light and blue light.

3. The method according to claim 1, characterized in that: When the strawberry variety is Xiangye, the light duration in each 24-hour light cycle is 16 hours.

4. The method according to claim 1, characterized in that: When the strawberry variety is Xiangye, the start time of the photoperiod is ZT0, and the start time of illumination is at least 8 hours from ZT0.

5. The method according to any one of claims 1 to 4, characterized in that: When the strawberry variety is Xiangye, any one of white light, red light and blue light is used for illumination, and the illumination duration is 16 hours. The start time of the light cycle is ZT0, and the start time of illumination is 8 hours from ZT0.

6. The method according to claim 1, characterized in that: When the strawberry variety is light snow, the lighting adopts white light.

7. The method according to claim 1, characterized in that: When the strawberry variety is light snow, the light duration in each 24-hour light cycle is 12 hours.

8. The method according to claim 1, characterized in that: When the strawberry variety is light snow, the start time of the photoperiod is ZT0, and the start time of illumination is 4-12 hours from ZT0.

9. The method according to any one of claims 6 to 8, characterized in that: When the strawberry variety is light snow, white light is used for illumination, the illumination time is 12 hours, the start time of the light cycle is ZT0, and the start time of illumination is 4-12 hours from ZT0.

10. The method according to any one of claims 1 to 9, characterized in that: The refrigerated temperature is 4°C.

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