Durian ripening technology

Abstract

The invention discloses a durian ripening process, which comprises a cold storage step, a fruit fermentation step and a ripening operation step, in the ripening operation step, factors such as pulp temperature, ethylene concentration, carbon dioxide concentration, humidity and the like are controlled according to the ripening grade required by durian to carry out adaptive standard quantitative regulation and control; according to the durian ripening method, the ripening grade of the durian can be standardized and controlled, large-scale ripening of the durian can be achieved, the ripening grade of the durian in the same batch is uniform, the ripening quality is high, and the damage to goods is small.

Description

Technical Field

[0001] The invention belongs to the technical field of fruit ripening, and particularly relates to a durian ripening process. Background Art

[0002] Durian is a tropical fruit known as the "king of fruits". Durian has high nutritional value and is rich in various vitamins and essential amino acids. Its dietary fiber can control blood sugar and promote intestinal motility. In recent years, it has been favored by consumers in China. Its unique and rich flavor and rich nutritional value have led to a continuous increase in market demand. However, the main production areas of durian are mainly in some Southeast Asian countries, among which Thailand has the largest planting. Therefore, durian mostly needs to be transported and stored over long distances to enter the Chinese market. Therefore, fruit farmers usually pick durian when it reaches about 5 to 6 mature. At this time, the durian is green in appearance, the thorns are hard, the flesh is hard, and the taste is dry. It cannot be eaten directly. It needs to be ripened (ripened) to reach full maturity before it can be eaten. Durian is a post-ripening fruit with respiratory climacteric. Currently, the conventional operation for ripening durian is to use natural ripening methods, such as placing durian directly at room temperature for 1-7 days to achieve ripening; uneven maturity, half-ripe fruit rot, or putting durian in a paper bag, sealing the bag mouth, creating a closed environment to prevent air from entering, and using the ethylene gas released by durian to increase the concentration of ethylene gas, thereby accelerating the ripening speed. However, the maturity of durian is uncontrollable, and the same batch of durian will have different maturity, and the durian flesh is prone to half-ripe, or the flesh color is dull, affecting the ripening quality; there are also methods of Chemical ripening method, commonly used is to apply ethylene to the surface of durian after diluting it, or to place durian in ethylene solution and soak it for a while, then take it out and dry it, but the above operation is not only cumbersome, it is necessary to process durian one by one, increase labor cost, and ethylene metering cannot be evenly controlled, and it is also easy to cause the problem of different maturity of durian in the same batch, such as ethylene concentration is too large, it is easy to cause the local temperature of durian to be high, it is easy and causes durian maturity to be too fast and uneven, and cracking occurs, affecting taste and quality, and ripening to the time of full maturity is usually 7-10 days, the time is long, and it will affect the supply turnover. And along with the continuous expansion of durian market, durian usually will be transported in batches and catalyzed, and the operation of existing durian ripening obviously cannot meet its large-scale and standardized ripening demand. Moreover, current durian is usually first concentrated to be transported to a distribution center or distribution site, and then distributed after being concentrated to ripen. However, different durian distributors have different considerations and need to ripen products to different maturity levels, but the current durian ripening processes do not take into account the controllable and scalable ripening operations that can reach different ripening levels. Summary of the invention

[0003] Based on the above background, the present invention discloses a durian ripening process, which can standardize and control the maturity level of durian by performing standard quantitative control on factors such as pulp temperature, ethylene gas concentration, and carbon dioxide concentration during the ripening process, and can also perform large-scale ripening of durian, so that durians of the same batch have uniform maturity levels, high ripening quality, and low loss.

[0004] The technical solution of the present invention is:

[0005] A durian ripening process comprises the following steps:

[0006] S1: Refrigerate the durian with maturity level 1 at 10℃~15℃ and relative humidity 90%~95%.

[0007] Durian is a fruit with respiratory hysteresis. Low temperature can delay but not completely inhibit metabolism. Ethylene is continuously released, and even a small amount of it can promote slow ripening, leading to over-ripening or fermentation of the flesh.

[0008] S2: After taking out the durian from the refrigerated environment, heating it, raising the temperature of the durian pulp from 10°C to 15°C to 22°C to 24°C at a heating rate of 1°C to 2°C / hour, and maintaining the constant temperature for 5-8h;

[0009] S3: According to the required maturity level of durian, the ripening operation of durian is as follows:

[0010] S3.1 When the durian is ripened to maturity level 2-3

[0011] The durian that has been subjected to the heating and constant temperature treatment in step S2 is placed in a relatively closed environment, the temperature is raised to 18° C., and the carbon dioxide concentration in the environment is controlled to be 5%-10%, the ethylene gas concentration is 300 ppm, and the humidity is 90%-95%, and maintained for 28 hours; the durian is evenly ripened, and the 2 to 3 grade flesh is soft and moderately sweet.

[0012] S3.2 Ripening durian to maturity level 3-4

[0013] The durian ripened to maturity level 2-3 in step S3.1 is heated to a pulp temperature of 22° C., and the carbon dioxide concentration in the environment is controlled to be 0.4%-0.6%, the ethylene gas concentration is 300-500 ppm, and the humidity is 90%-95% for 20-26 hours;

[0014] S3.3 Ripening durian to level 5

[0015] The durian ripened to maturity level 3-4 in step S3.2 is cooled to a pulp temperature of 15°C, and the carbon dioxide concentration in the environment is controlled to 4000-5000ppm and the humidity is controlled to 90%-95% for 20-28 hours.

[0016] The purpose of cooling in this step is to inhibit post-ripening metabolism and extend the shelf life.

[0017] Furthermore, in steps S1 to S4, the maturity level of durian is divided according to the peel, flesh and smell, and the standards of the maturity levels are as follows:

[0018] Level 1:

[0019] The fruit peel is green and the thorns are hard; the puncture force is >50N and there is no deformation when pressed by the thumb.

[0020] At this time, the pulp cells contain more starch, and the pectin and other substances between the cells are tightly connected, making the pulp and the peel fit tightly. The pulp is white, hard in texture, and does not sink when pressed.

[0021] It exudes a green and astringent smell;

[0022] Level 2:

[0023] The fruit skin is mostly turquoise, but a small part has turned yellow-green. The fruit skin turns yellow-green, and the area is 70% to 80% larger than turquoise, and the yellow-green area is 15% to 30%. The fruit thorns are hard;

[0024] The flesh is white and hard;

[0025] It exudes a green and astringent smell;

[0026] Level 3:

[0027] The peel is turquoise and yellow-green, with the color area of ​​the peel being 40% to 60% turquoise and 40% to 60% yellow-green. Some of the thorns have become soft, with a hardness of 30-40N, and a 30% to 50% indentation when pressed by the thumb.

[0028] The flesh becomes soft, deforms when pressed, and is golden in color. The core is allowed to be slightly milky white.

[0029] Exudes durian aroma;

[0030] Level 4:

[0031] The fruit skin is basically light yellow, and all the thorns become soft;

[0032] The flesh has a medium texture and is light yellow in color;

[0033] Exudes durian aroma;

[0034] Level 5:

[0035] The fruit skin is bright yellow, and the thorns are elastic when pressed;

[0036] The flesh is soft and juicy (juice appears when pressed), and golden in color;

[0037] Exudes durian aroma.

[0038] Furthermore, in step S3, the durian is placed in a relatively closed environment, that is, the durian is placed in a ripening warehouse with a pressure difference control circulation system.

[0039] Furthermore, it also includes step S4: controlling the temperature of the ripened durian pulp to 10° C. to 12° C., and controlling the carbon dioxide concentration in the environment to 3000 ppm and the humidity to 90% to 95%;

[0040] Furthermore, it also includes step S5: refrigerating the durian processed in step S4 at 10°C.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention finds that durian ripening is affected by humidity and carbon dioxide concentration in addition to temperature and ethylene concentration during the ripening process. Therefore, the present invention creatively performs standardized and controllable ripening levels of durian according to demand by quantitatively controlling key factors such as pulp temperature, humidity, ethylene gas concentration and carbon dioxide concentration. The present invention can also meet the large-scale ripening requirements of durian, and durians in the same batch have uniform ripening levels, high ripening quality and low loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 The present invention provides photos of the appearance of durian of different grades (color numbers): color No. 1 in the photo corresponds to maturity No. 1, color No. 2 corresponds to maturity No. 2, color No. 3 corresponds to maturity No. 3, color No. 4 corresponds to maturity No. 4, and color No. 5 corresponds to maturity No. 5. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] The present invention divides the maturity of durian into five levels according to the peel, pulp and smell, namely, level 1, level 2, level 3, level 4 and level 5. The above-divided levels can also be correspondingly called maturity No. 1, maturity No. 2, maturity No. 3, maturity No. 4 and maturity No. 5 according to the industry;

[0047] The specific classification criteria are as follows:

[0048] Level 1 (Maturity Level 1):

[0049] The fruit skin is green, the thorns are hard; the puncture force is greater than 50N, and there is no deformation when pressed by the thumb

[0050] At this time, the pulp cells contain more starch, and the pectin and other substances between the cells are tightly connected, so that the pulp and the peel fit tightly together. The pulp is white, hard, and does not sink when pressed.

[0051] It exudes a green and astringent smell;

[0052] Level 2 (Maturity Level 2):

[0053] The fruit skin is mostly turquoise, but a small part has turned yellow-green. The fruit skin turns yellow-green, and the area is 70% to 80% larger than turquoise, and the yellow-green area is 15% to 30%. The fruit thorns are hard;

[0054] The flesh is white and hard;

[0055] It exudes a green and astringent smell;

[0056] Level 3 (Maturity Level 3):

[0057] The peel is turquoise and yellow-green, with the color area of ​​the peel being 40% to 60% turquoise and 40% to 60% yellow-green. Some of the thorns have become soft, with a hardness of 30-40N, and a 30% to 50% indentation when pressed by the thumb.

[0058] The flesh becomes soft, deforms when pressed, and is golden in color. The core is allowed to be slightly milky white.

[0059] Exudes durian aroma;

[0060] Level 4 (Maturity Level 4):

[0061] The fruit skin is basically light yellow, and all the thorns become soft;

[0062] The flesh has a medium texture and is light yellow in color;

[0063] Exudes durian aroma;

[0064] At this time, some cells begin to produce juice. The starch in the pulp cells undergoes continuous hydrolysis, and the pectin between cells is further decomposed, making the pulp soft and having a certain amount of juice. These juices contain nutrients such as sugars and vitamins.

[0065] Level 5 (Maturity Level 5):

[0066] The fruit skin is bright yellow, and the thorns are elastic when pressed;

[0067] The flesh is soft and juicy (juice appears when pressed), and golden in color;

[0068] Exudes durian aroma.

[0069] At this time, the starch in the pulp cells is converted into sugars in large quantities, the connection between cells is loose, and the juice increases, so the pulp becomes very soft and juicy;

[0070] Embodiment 1: A durian ripening process comprises the following steps:

[0071] S1: refrigerate the durian with maturity grade 1 at 10° C. to 15° C. and relative humidity of 90% to 95%;

[0072] Specifically, the refrigeration time of this step is 3-7 days.

[0073] S2: After taking out the durian from the refrigerated environment, heating it, raising the temperature of the durian pulp from 10°C to 15°C to 22°C at a heating rate of 1°C-2°C / hour, and maintaining the constant temperature for 6h;

[0074] In specific application, if the temperature in this step is higher than 24 degrees, it will cause a sudden increase in the respiration intensity of the pulp, accelerate the production of ethanol odor by anaerobic respiration and increase the risk of mold proliferation; if it is lower than 20 degrees, the activity of ethylene synthase in the pulp is insufficient, and the rate of starch conversion to sugar is reduced.

[0075] S3: Ripen the durian to maturity level 2-3

[0076] The durian after the heating and constant temperature treatment in step S2 is placed in a relatively closed environment, the temperature is raised to 18° C., and the carbon dioxide concentration in the environment is controlled to be 5%-10%, the ethylene gas concentration is 300 ppm, and the humidity is 90%-95%, and maintained for 28 hours;

[0077] The so-called relative closure in this step refers to the unnatural exchange of air inside the warehouse with the air outside the warehouse, which needs to be controlled by the cooperation of relevant equipment.

[0078] S4: Controlling the temperature of the ripened durian pulp at 10° C. to 12° C., and controlling the carbon dioxide concentration in the environment to 3000 ppm and the humidity to 90% to 95% for 6-8 hours.

[0079] S5: refrigerate the durian treated in step S4 at 10°C.

[0080] Embodiment 2: A durian ripening process comprises the following steps:

[0081] S1: refrigerate the durian with maturity grade 1 at 10° C. to 15° C. and relative humidity of 90% to 95%;

[0082] Specifically, the refrigeration time of this step is 3-7 days.

[0083] S2: After taking out the durian from the refrigerated environment, heating it, raising the temperature of the durian pulp from 10°C to 15°C to 22°C at a heating rate of 1°C-2°C / hour, and maintaining the constant temperature for 6h;

[0084] S3: Ripen the durian to maturity level 3-4

[0085] S3.1 Place the durian after the heating and constant temperature treatment in step S2 in a relatively closed environment, heat it to a temperature of 18°C ​​for the durian pulp, and control the carbon dioxide concentration in the environment to 5%-10%, the ethylene gas concentration to 300ppm, and the humidity to 90%-95%, and keep it for 28 hours;

[0086] S3.2 raising the temperature of the durian ripened to maturity level 2-3 in step S3.1 to a pulp temperature of 22°C, and controlling the carbon dioxide concentration in the environment to 0.4%-0.6%, the ethylene gas concentration to 300-500ppm, and the humidity to 90%-95% for 24 hours;

[0087] S4: controlling the temperature of the ripened durian pulp to 10° C. to 12° C., and controlling the carbon dioxide concentration in the environment to 3000 ppm and the humidity to 90% to 95% for 6-8 hours;

[0088] S5: refrigerate the durian treated in step S4 at 10°C.

[0089] Embodiment 3: A durian ripening process comprises the following steps:

[0090] S1: refrigerate the durian with maturity grade 1 at 10° C. to 15° C. and relative humidity of 90% to 95%;

[0091] Specifically, the refrigeration time of this step is 3-7 days.

[0092] S2: After taking out the durian from the refrigerated environment, heating it, raising the temperature of the durian pulp from 10°C to 15°C at a heating rate of 1°C-2°C / hour to 22°C, and maintaining the constant temperature for 6h;

[0093] S3: Ripen durian to level 5

[0094] S3.1 Place the durian after the heating and constant temperature treatment in step S2 in a relatively closed environment, heat it to a temperature of 18°C ​​for the durian pulp, and control the carbon dioxide concentration in the environment to 5%-10%, the ethylene gas concentration to 300ppm, and the humidity to 90%-95%, and keep it for 28 hours;

[0095] S3.2 raising the temperature of the durian ripened to maturity level 2-3 in step S3.1 to a pulp temperature of 22°C, and controlling the carbon dioxide concentration in the environment to 0.4%-0.6%, the ethylene gas concentration to 300-500ppm, and the humidity to 90%-95% for 24 hours;

[0096] S3.3 The durian ripened to maturity level 3-4 in step S3.2 is cooled to a pulp temperature of 15°C, and the carbon dioxide concentration in the environment is controlled to 4500ppm and the humidity is controlled to 90%-95% for 24 hours.

[0097] S4: controlling the temperature of the ripened durian pulp to 10° C. to 12° C., and controlling the carbon dioxide concentration in the environment to 3000 ppm and the humidity to 90% to 95% for 6-8 hours;

[0098] S5: refrigerate the durian treated in step S4 at 10°C.

[0099] Application examples:

[0100] This application example ripens 2 tons of Gan Yao variety durian from Thailand to the Hunan ripening base in March.

[0101] The durian transported from Thailand to the Hunan base is at maturity level 1 when it enters the warehouse. It will be transported to a cold storage or freezer for preservation. The temperature of the environment in the cold storage or freezer is 10℃~15℃ and the relative humidity is 90%~95%.

[0102] Then, according to customer needs, we plan to ripen 300kg to level 2-3, 700kg to level 3-4, and the rest to level 5.

[0103] When doing specific operations;

[0104] 1) First, 2 tons of durian are transferred to the first ripening warehouse. Under the condition of natural air circulation, the temperature of the ripening warehouse is raised to 22°C from 10°C to 15°C, and the temperature is kept constant for 6 hours;

[0105] In this step, the durian is stacked in sections of 300kg, 700kg, and 1 ton according to the maturity level of the planned ripening;

[0106] Durian is a late-ripening fruit with respiratory climacteric. Its respiration is suppressed in a cold storage environment of 10℃~15℃. In this step, the temperature is raised and maintained at a constant temperature. During the heating process and the constant temperature maintenance process, the respiration intensity of durian gradually increases and the carbon dioxide in the storage gradually increases. This stage is the fruit awakening process.

[0107] 2) Then the ripening warehouse is closed, and the durian after the heating and constant temperature treatment is placed in a relatively closed environment, and the temperature is raised to 18° C., and the carbon dioxide concentration in the environment is controlled to be 5%-10%, the ethylene gas concentration is 300ppm, and the humidity is 90%-95%. After maintaining for 28 hours, the maturity level of the durian is 2-3;

[0108] During the above process, the respiration intensity of durian increases, and the flesh of durian can better absorb ethylene gas. The ethylene in the air can induce the synthesis and activity of cell wall hydrolases (such as cellulase, pectinase, etc.) in the durian flesh. These enzymes will decompose the cellulose and pectin components in the cell wall. The starch and other polysaccharides in the durian flesh will be accelerated to decompose into monosaccharides such as glucose and fructose under the action of ethylene. The soluble sugar content in the durian fruit increases, and the durian will reach the peak of respiration at this time;

[0109] The ripening warehouse in this application example adopts the Chinese patent number 2024212684275 previously applied by the applicant, "An Energy-Saving Fruit Pressure Differential Ripening Warehouse", which discloses a ripening warehouse with a pressure differential control circulation system. During use, the pressure differential circulation system can be used to allow durian to be evenly exposed to ethylene, and the temperature distribution is more uniform, so that the flesh can be ripened from the inside out and evenly. In the specific application process, durian can be randomly and evenly selected to make a hole, and the probe of the temperature sensor can be inserted into the flesh to detect the temperature of the flesh.

[0110] 3) After 300 kg of durian ripened to maturity level 2-3 is transferred to the second ripening warehouse, the temperature of the durian pulp is controlled at 10° C. to 12° C., and the carbon dioxide concentration in the environment is controlled to 3000 ppm and the humidity is controlled to 90% to 95% for 8 hours; then it is refrigerated at 10° C.

[0111] The temperature of the remaining durian in the first ripening warehouse is raised to 22°C, and the carbon dioxide concentration in the environment is controlled at 0.4%-0.6%, and the humidity is 90%-95% for 24 hours. At this time, the maturity level of the durian in the first ripening warehouse is 3-4. In the process of ripening the durian with a maturity level of 2-3 to 3-4, the color of the durian shell will gradually change, the chlorophyll in the durian shell will gradually decompose, and the physiological metabolic activity of its pulp will continue to increase. At the cellular level, the respiration of mitochondria will be further accelerated, and at the same time, the synthesis of some pigments such as carotenoids will increase, which will continuously consume oxygen and produce carbon dioxide.

[0112] 4) After transferring 700 kg of durians in the first ripening warehouse to the third ripening warehouse, the temperature of the durian pulp is controlled at 10° C. to 12° C., and the carbon dioxide concentration in the environment is controlled to 3000 ppm and the humidity is controlled to 90% to 95% for 8 hours; and then refrigerated at 10° C.

[0113] The temperature of the remaining durian in the first ripening warehouse is reduced to 15°C, and the carbon dioxide concentration in the environment is controlled to 4500ppm, and the humidity is 90% to 95%, and maintained for 24 hours. At this time, the maturity level of the durian in the first ripening warehouse is level 5; the temperature of the durian flesh is controlled at 10°C to 12°C, and the carbon dioxide concentration in the environment is controlled to 3000ppm, and the humidity is 90% to 95%, and the maintenance time is 8 hours; then refrigerated at 10°C. In the process of ripening the durian with maturity levels of 3 to 4 to level 5, all ethylene is discharged (that is, the ethylene concentration is 0), and the fruit temperature is continued to be reduced, and the air in the warehouse is exchanged with the air in the warehouse to reduce the concentration of carbon dioxide volume in the warehouse. At this time, the color of the durian shell fades as a whole, and the chlorophyll is golden yellow. The hardness and starch content of the flesh decrease, and the fruit gradually turns yellow, and some parts are still half-cooked, corresponding to which the soluble solids and total sugar content increase.

[0114] In step 3), when 300 kg of durians were transferred to the second ripening warehouse, random samples were taken to confirm the maturity and yield of the durians. The number of samples was 15, of which 14 samples had a maturity level of 2 to 3. The peel of the remaining sample was damaged and opened when it was put into storage, so it was not included in the maturity statistics.

[0115] In step 4), when 700 kg of durian is transferred to the third ripening warehouse, random samples are taken to confirm the maturity and yield of the durian. The number of samples is 25, of which 23 samples have a maturity level of 3 to 4, and the remaining 2 samples still have a maturity level of 2 to 3.

[0116] In step 4), random sampling was performed on durians that were expected to be ripened to maturity level 5. There were 35 samples sampled, of which 29 samples had a maturity level of 5, the remaining 2 were over-mature, the other 3 had a maturity level of 3-4, and 1 had a maturity level of 2-3.

[0117] The cargo damage rate of the corresponding use case is statistically analyzed, and the cargo damage rate is only 0.8%, which is low.

[0118] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A durian ripening process, characterized in that, It includes the following steps: S1: Refrigerate the durian with maturity level 1 at 10℃~15℃ and relative humidity 90%~95%. Durian is a fruit with respiratory hysteresis. Low temperature can delay but not completely inhibit metabolism. Ethylene is continuously released, and even a small amount of it will promote slow ripening, leading to over-ripening or fermentation of the flesh. S2: After taking out the durian from the refrigerated environment, heating it, raising the temperature of the durian pulp from 10°C to 15°C to 22°C to 24°C at a heating rate of 1°C to 2°C / hour, and maintaining the constant temperature for 5-8h; S3: According to the required maturity level of durian, the ripening operation of durian is as follows: S3.1 When the durian is ripened to maturity level 2-3 The durian that has been subjected to the heating and constant temperature treatment in step S2 is placed in a relatively closed environment, the temperature is raised to 18° C., and the carbon dioxide concentration in the environment is controlled to be 5%-10%, the ethylene gas concentration is 300 ppm, and the humidity is 90%-95%, and maintained for 28 hours; the durian is evenly ripened, and the 2 to 3 grade flesh is soft and moderately sweet. S3.2 Ripening durian to maturity level 3-4 The durian ripened to maturity level 2-3 in step S3.1 is heated to a pulp temperature of 22° C., and the carbon dioxide concentration in the environment is controlled to be 0.4%-0.6%, the ethylene gas concentration is 300-500 ppm, and the humidity is 90%-95% for 20-26 hours; S3.3 Ripening durian to level 5 The durian ripened to maturity level 3-4 in step S3.2 is cooled to a pulp temperature of 15°C, and the carbon dioxide concentration in the environment is controlled to 4000-5000ppm and the humidity is controlled to 90%-95% for 20-28 hours.

2. A durian ripening process according to claim 1, characterized in that, In steps S1 to S4, the maturity level of durian is divided according to the peel, flesh and smell, and the standards of the maturity levels are as follows: Level 1: The fruit peel is green and the thorns are hard; the puncture force is >50N and there is no deformation when pressed by the thumb. At this time, the pulp cells contain more starch, and the pectin and other substances between the cells are tightly connected, making the pulp and the peel fit tightly. The pulp is white, hard in texture, and does not sink when pressed. It exudes a green and astringent smell; Level 2: The fruit skin is mostly turquoise, but a small part has turned yellow-green. The fruit skin turns yellow-green, and the area is 70% to 80% larger than turquoise, and the yellow-green area is 15% to 30%. The fruit thorns are hard; The flesh is white and hard; It exudes a green and astringent smell; Level 3: The peel is turquoise and yellow-green, with the color area of ​​the peel being 40% to 60% turquoise and 40% to 60% yellow-green. Some of the thorns have become soft, with a hardness of 30-40N, and a 30% to 50% indentation when pressed by the thumb. The flesh becomes soft, deforms when pressed, and is golden in color. The core is allowed to be slightly milky white. Exudes durian aroma; Level 4: The fruit skin is basically light yellow, and all the thorns become soft; The flesh has a medium texture and is light yellow in color; Exudes durian aroma; Level 5: The fruit skin is bright yellow, and the thorns are elastic when pressed; The flesh is soft and juicy (juice appears when pressed), and golden in color; Exudes durian aroma.

3. A durian ripening process according to claim 1, characterized in that, In step S3, the durian is placed in a relatively closed environment, that is, the durian is placed in a ripening warehouse with a pressure difference control circulation system.

4. A durian ripening process according to claim 1, characterized in that, The method further comprises step S4: controlling the temperature of the ripened durian pulp to be between 10° C. and 12° C., and controlling the carbon dioxide concentration in the environment to be 3000 ppm and the humidity to be between 90% and 95%.

5. A durian ripening process according to claim 1, characterized in that, The method further comprises step S5: refrigerating the durian processed in step S4 at 10°C.

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