Freezing method of konjak fresh fruit

Abstract

This invention discloses a method for the frozen preservation of fresh konjac fruit, belonging to the field of agricultural product preservation and processing technology. This invention solves the problems of nutrient loss, textural damage, and short preservation periods associated with conventional preservation methods through a process coupling design involving raw material pretreatment, composite color protection treatment, gradient precooling treatment, segmented quick-freezing-freezing treatment, and low-temperature slow thawing treatment. It enables long-term stable preservation of konjac corms for 6-12 months, with a glucomannan retention rate ≥89%, browning degree (ΔE) ≤3.5, and juice loss rate ≤5%. After thawing, the corms can be directly used for subsequent processing, eliminating the slicing, drying, grinding, and rehydration steps required in traditional processes.

Description

Technical Field

[0001] This invention belongs to the field of agricultural product preservation and processing technology, and more specifically, relates to a method for freezing and preserving fresh konjac fruit. Background Technology

[0002] Konjac is a perennial herbaceous plant belonging to the genus Amorphophallus in the family Araceae. Its tubers are rich in glucomannan, starch, dietary fiber, and various minerals, making it an agricultural product with both nutritional and processing value. Traditional konjac processing faces challenges due to the highly seasonal nature of fresh konjac fruits, with harvesting typically concentrated in autumn. Furthermore, the fresh fruits contain approximately 85%-90% water and are fragile, making them susceptible to microbial contamination and spoilage. This makes preservation difficult and processing cycles short, limiting year-round production in the konjac industry.

[0003] The mainstream method for preserving fresh konjac fruit is to wash, slice, dry, and grind it into dried konjac powder, thus achieving long-term preservation by reducing moisture content. However, this process has significant drawbacks: during drying, some heat-sensitive nutrients (such as vitamins and active polysaccharides) in the fresh konjac fruit degrade and are lost, and high-temperature treatment destroys the natural structure of fresh starch, resulting in processed products (such as konjac tofu and konjac gel) having a dry texture and insufficient chewiness, losing the fresh and crisp taste of the original konjac fruit. Furthermore, dried konjac powder needs to be rehydrated before subsequent use, which not only increases processing steps but may also affect product quality due to uneven rehydration, failing to fully utilize the fresh starch characteristics of the konjac fruit.

[0004] Furthermore, there are few reports on direct preservation methods for fresh konjac fruit. Some low-temperature refrigeration technologies can only delay the decay of fresh fruit for a short period of time (1-2 weeks) and cannot achieve long-term preservation for more than several months. In addition, fresh konjac fruit will still undergo respiration during refrigeration, resulting in starch conversion and a deterioration in taste.

[0005] Therefore, there is an urgent need for a preservation method that can overcome the seasonal limitations of fresh konjac fruit, achieve long-term preservation, retain its nutritional components and fresh starch texture to the maximum extent, and can be directly used for subsequent processing, eliminating the need for the starch-making step. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the technical problem to be solved by the present invention is to provide a method for the cryopreservation of fresh konjac fruit. Through process coupling and parameter optimization, the long-term stable preservation of konjac corms is achieved, significantly improving the browning inhibition effect, the retention rate of effective components and the textural stability. Furthermore, it can be directly used for subsequent processing, simplifying the production process.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for freezing and preserving fresh konjac fruit, comprising the following steps:

[0009] 1) Raw material pretreatment;

[0010] 2) Immerse the pretreated konjac blanks obtained in step 1) in the color-protecting solution, rinse, and drain.

[0011] 3) Place the konjac blanks after color protection in step 2) into a pre-cooling device for gradient pre-cooling. First, pre-cool at 8~10℃, then lower to 0~4℃, so that the center temperature of the konjac blanks is stably reduced to 6~7℃.

[0012] 4) Place the pre-cooled konjac blanks from step 3) into a tunnel-type quick-freezing machine for segmented quick-freezing. In the first stage, quick-freeze at -32℃ to a surface temperature of -10℃. In the second stage, quick-freeze at -35℃ to a core temperature of -28℃ to -18℃. After constant temperature freezing treatment, store the frozen food.

[0013] 5) The frozen konjac blanks preserved in step 4) are subjected to low-temperature slow thawing treatment for subsequent konjac product processing.

[0014] Preferably, in step 1), the raw material pretreatment process is as follows: select konjac tubers with uniform maturity and no damage or mold, remove the fibrous roots and surface mud, rinse with 0.1~0.2MPa high-pressure spray water 3~5 times, place in a sterile environment to drain until there are no visible water droplets on the surface, and process into blocks of (5~50)mm×(5~50)mm or strips of (5~20)mm×(20~200)mm by a strip cutter or dicing machine to obtain pretreated konjac blanks.

[0015] Preferably, in step 2), the color-protecting solution consists of 0.3% citric acid, 0.2% sodium ascorbate, 0.8% trehalose, 0.05% xanthan gum, and the remainder deionized water by weight percentage.

[0016] Preferably, in step 2), the soaking time is 25-30 minutes, and the mixture is stirred every 6 minutes. During the soaking process, the color-protecting liquid completely covers the konjac blank.

[0017] Preferably, in step 3), the temperature switching time of gradient precooling is 30 min, and the temperature fluctuation of the center of the konjac blank after precooling is ≤0.5℃.

[0018] Preferably, in step 3), the temperature is first pre-cooled at 8~10℃ for 30 minutes, and then lowered to 0~4℃ for 1 hour.

[0019] Preferably, in step 4), the wind speed for the first stage of quick-freezing is 4 m / s, and the wind speed for the second stage of quick-freezing is 5 m / s.

[0020] Preferably, in step 4), the first stage of quick-freezing takes 1.5 hours, and the second stage of quick-freezing takes 1 hour.

[0021] Preferably, in step 4), the constant temperature freezing temperature is -18℃ to -5℃, and the relative humidity is 90% to 95%.

[0022] Preferably, in step 5), the low-temperature slow thawing process is as follows: the frozen konjac blank is placed in a refrigerated environment at 4°C and 85-90% humidity for 10 hours to thaw until the core temperature rises to 0-2°C.

[0023] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0024] 1) This invention enables konjac corms to be stably stored for 6 to 8 months at -5℃ to -18℃ through pretreatment, color protection, precooling and segmented freezing processes, which far exceeds the 1 to 2 weeks of traditional cold storage and the indirect storage mode of drying process. It effectively solves the problem of strong seasonality and short storage period of konjac corms, and realizes year-round processing and utilization.

[0025] 2) This invention uses low-temperature freezing instead of traditional high-temperature drying, avoiding the degradation and loss of heat-sensitive nutrients (vitamin C, active glucomannan); at the same time, the composite color protection treatment can effectively inhibit browning reaction, and the gradient precooling and segmented quick-freezing process reduces cell rupture, maximizing the preservation of the natural structure of fresh starch. The subsequent processed products have a fresh taste and sufficient toughness, which is significantly better than products processed from dried konjac flour.

[0026] 3) The konjac blocks preserved by this invention can be directly used for subsequent processing after thawing, which eliminates the steps of slicing, drying, grinding and rehydration in the traditional process. This not only reduces equipment investment and energy consumption, but also avoids quality loss during the grinding and rehydration process.

[0027] 4) The process steps of this invention are clear, the required reagents (citric acid, sodium ascorbate, etc.) are inexpensive and easy to obtain, and the freezing and thawing equipment are conventional equipment for agricultural product processing, without the need for special customization. It can be widely used in large-scale konjac processing enterprises and small and medium-sized workshops. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described below with reference to specific embodiments. Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0029] Example 1

[0030] A method for freezing and preserving fresh konjac fruit, the specific steps of which are as follows:

[0031] 1) Select konjac tubers that are 12 days after the expansion period, with uniform maturity and smooth, undamaged skin. The weight of a single tuber should be 800-1200g. Remove the fibrous roots and surface mud and sand, rinse with clean water using a 0.15MPa high-pressure sprayer 4 times, place them on a sterile operating table to drain the surface water, and process them into 20mm×20mm blocks using a dicing machine to obtain pre-treated konjac blocks.

[0032] 2) Mix 0.3% citric acid, 0.2% sodium ascorbate, 0.8% trehalose, 0.05% xanthan gum and the balance deionized water to obtain a color-protecting solution;

[0033] 3) Immerse the pretreated konjac blocks from step 1) in the color-protecting solution from step 2) for 26 minutes, stirring every 6 minutes. After soaking, rinse quickly with deionized water for 30 seconds and drain.

[0034] 4) Place the konjac blocks that have been color-protected in step 3) into a refrigerator, pre-cool them at 9℃ for 30 minutes, and then pre-cool them at 2℃ for 1 hour to make the center temperature stabilize at 6.5℃ with a center temperature fluctuation range ≤0.5℃.

[0035] 5) Spread the pre-cooled konjac blocks from step 4) evenly on a freezing tray with a spacing of 1.5 cm, and place them in a tunnel-type quick-freezing machine. In the first stage, quick-freeze at -32℃ and a wind speed of 4 m / s for 1.5 hours until the surface temperature drops to -10℃. In the second stage, quick-freeze at -35℃ and a wind speed of 5 m / s for 1 hour until the core temperature drops to -22℃. Then transfer them to a cold storage and store them at a constant temperature of -12℃±0.5℃ and a relative humidity of 92%.

[0036] 6) After 6 months of storage, take out the konjac blocks and thaw them in a refrigerated environment at 4℃ and 88% humidity for 10 hours. After thawing, the core temperature will rise to 1℃, which can then be used for the subsequent production of konjac tofu.

[0037] Example 2

[0038] A method for freezing and preserving fresh konjac fruit, the specific steps of which are as follows:

[0039] 1) Select konjac tubers that are 10 days after the expansion period, with uniform maturity and smooth, undamaged skin, with a single tuber weight of 500-800g. Remove the fibrous roots and surface mud and sand, rinse three times with clean water using a 0.1MPa high-pressure spray, place them on a sterile operating table to drain the surface moisture, and process them into 12mm×80mm blocks using a dicing machine to obtain pre-treated konjac blocks;

[0040] 2) Mix 0.3% citric acid, 0.2% sodium ascorbate, 0.8% trehalose, 0.05% xanthan gum and the balance deionized water to obtain a color-protecting solution;

[0041] 3) Immerse the pretreated konjac blocks from step 1) in the color-protecting solution from step 2) for 25 minutes, stirring every 6 minutes. After soaking, rinse quickly with deionized water for 25 seconds and drain.

[0042] 4) Place the konjac blocks that have been color-protected in step 3) into a refrigerator, pre-cool them at 8℃ for 30 minutes, and then pre-cool them at 0℃ for 1 hour to make the center temperature stabilize at 6℃, with a center temperature fluctuation range of ≤0.5℃.

[0043] 5) Spread the pre-cooled konjac blocks from step 4) evenly on a freezing tray with a spacing of 1.5 cm, and place them in a tunnel-type quick-freezing machine. In the first stage, quick-freeze at -32℃ and a wind speed of 4 m / s for 1.5 hours until the surface temperature drops to -10℃. In the second stage, quick-freeze at -35℃ and a wind speed of 5 m / s for 1 hour until the core temperature drops to -20℃. Then transfer them to a cold storage and store them at a constant temperature of -10℃±0.5℃ and 90% relative humidity.

[0044] 6) After 7 months of storage, take out the konjac blocks and thaw them in a refrigerated environment at 4℃ and 85% humidity for 10 hours. After thawing, the core temperature will rise to 0.8℃, which can be used for subsequent konjac gel production.

[0045] Example 3

[0046] A method for freezing and preserving fresh konjac fruit, the specific steps of which are as follows:

[0047] 1) Select konjac tubers that are 15 days after the expansion period, with uniform maturity and smooth, undamaged skin, and a single tuber weight of 1200~1500g. Remove the fibrous roots and surface mud and sand, rinse 5 times with clean water using a 0.2MPa high-pressure spray, place them on a sterile operating table to drain the surface moisture, and process them into 30mm×30mm blocks using a dicing machine to obtain pre-treated konjac blocks;

[0048] 2) Mix 0.3% citric acid, 0.2% sodium ascorbate, 0.8% trehalose, 0.05% xanthan gum and the balance deionized water to obtain a color-protecting solution;

[0049] 3) Immerse the pretreated konjac blocks from step 1) in the color-protecting solution from step 2) for 28 minutes, stirring every 6 minutes. After soaking, rinse quickly with deionized water for 30 seconds and drain.

[0050] 4) Place the konjac blocks that have been color-protected in step 3) into a refrigerator, pre-cool them at 10℃ for 30 minutes, and then pre-cool them at 4℃ for 1 hour to make the center temperature stabilize at 7℃, with a center temperature fluctuation range of ≤0.5℃.

[0051] 5) Spread the pre-cooled konjac blocks from step 4) evenly on a freezing tray with a spacing of 1.5 cm, and place them in a tunnel-type quick-freezing machine. In the first stage, quick-freeze at -32℃ and a wind speed of 4 m / s for 1.5 hours until the surface temperature drops to -10℃. In the second stage, quick-freeze at -35℃ and a wind speed of 5 m / s for 1 hour until the core temperature drops to -25℃. Then transfer them to a cold storage and store them at a constant temperature of -15℃±0.5℃ and a relative humidity of 95%.

[0052] 6) After 8 months of storage, take out the konjac blocks and thaw them in a refrigerated environment at 4℃ and 90% humidity for 10 hours. After thawing, the core temperature will rise to 1.2℃, which can then be used for subsequent konjac product processing.

[0053] Example 4

[0054] A method for freezing and preserving fresh konjac fruit, the specific steps of which are as follows:

[0055] 1) Select konjac tubers that are 12 days after the expansion period, with uniform maturity and smooth, undamaged skin, with a single tuber weight of 800~1200g. Remove the fibrous roots and surface mud and sand, rinse with clean water four times using a 0.15MPa high-pressure spray, place them on a sterile operating table to drain the surface water, and process them into 5mm×5mm blocks using a dicing machine to obtain pre-treated konjac blocks;

[0056] 2) Mix 0.3% citric acid, 0.2% sodium ascorbate, 0.8% trehalose, 0.05% xanthan gum and the balance deionized water to obtain a color-protecting solution;

[0057] 3) Immerse the pretreated konjac blocks from step 1) in the color-protecting solution from step 2) for 25 minutes, stirring every 6 minutes. After soaking, rinse quickly with deionized water for 30 seconds and drain.

[0058] 4) Place the konjac blocks that have been color-protected in step 3) into a refrigerator, pre-cool them at 8℃ for 30 minutes, and then pre-cool them at 0℃ for 1 hour to make the center temperature stabilize at 6℃, with a center temperature fluctuation range of ≤0.5℃.

[0059] 5) Spread the pre-cooled konjac blocks from step 4) evenly on a freezing tray with a spacing of 1.5 cm, and place them in a tunnel-type quick-freezing machine. In the first stage, quick-freeze at -32℃ and a wind speed of 4 m / s for 1.5 hours until the surface temperature drops to -10℃. In the second stage, quick-freeze at -35℃ and a wind speed of 5 m / s for 1 hour until the core temperature drops to -20℃. Then transfer them to a cold storage and store them at a constant temperature of -12℃±0.5℃ and a relative humidity of 92%.

[0060] 6) After 7 months of storage, take out the konjac blocks and thaw them in a refrigerated environment at 4℃ and 88% humidity for 10 hours. After thawing, the core temperature will rise to 1℃, which can then be used for subsequent konjac product processing.

[0061] Example 5

[0062] A method for freezing and preserving fresh konjac fruit, the specific steps of which are as follows:

[0063] 1) Select konjac tubers that are 15 days after the expansion period, with uniform maturity and smooth, undamaged skin. The weight of a single tuber should be 1200-1500g. Remove the fibrous roots and surface mud and sand, rinse 5 times with clean water using a 0.2MPa high-pressure spray, place them on a sterile operating table to drain the surface water, and process them into 8mm×100mm blocks using a dicing machine to obtain pre-treated konjac strips.

[0064] 2) Mix 0.3% citric acid, 0.2% sodium ascorbate, 0.8% trehalose, 0.05% xanthan gum and the balance deionized water to obtain a color-protecting solution;

[0065] 3) Soak the pre-treated konjac strips from step 1) in the color-protecting solution from step 2) for 28 minutes, stirring once every 6 minutes. After soaking, rinse quickly with deionized water for 30 seconds and drain.

[0066] 4) Place the konjac strips that have been color-protected in step 3) into a refrigerator, pre-cool them at 10℃ for 30 minutes, and then pre-cool them at 4℃ for 1 hour to make the center temperature stabilize at 7℃, with a center temperature fluctuation range of ≤0.5℃.

[0067] 5) Spread the pre-cooled konjac strips from step 4) evenly on a freezing tray with a spacing of 1.5cm, and place them in a tunnel-type quick-freezing machine. In the first stage, quick-freeze at -32℃ and a wind speed of 4m / s for 1.5 hours until the surface temperature drops to -10℃. In the second stage, quick-freeze at -35℃ and a wind speed of 5m / s for 1 hour until the core temperature drops to -25℃. Then transfer them to a cold storage and store them at a constant temperature of -15℃±0.5℃ and a relative humidity of 95%.

[0068] 6) After 8 months of storage, take out the konjac strips and thaw them in a refrigerated environment at 4℃ and 90% humidity for 10 hours before using them for subsequent konjac noodle processing.

[0069] Comparative Example 1

[0070] Konjac tubers of the same specifications as in Example 1 were selected, washed, diced into 20mm×20mm pieces, dried at 70℃ for 4 hours, and pulverized into konjac powder. The powder was stored in a dry environment at room temperature for 6 months. When used, it was rehydrated with water to make konjac tofu. There was no loss of juice (after rehydration, the texture was significantly different from that of fresh products). The taste was dry, the toughness was insufficient, and there was a dried taste.

[0071] Comparative Example 2

[0072] Konjac tubers of the same specifications as in Example 1 were selected, washed, and diced into 20mm×20mm pieces using a dicing machine. No color protection treatment was applied. The tubers were pre-cooled directly at 0-4℃ for 1.5 hours (single-temperature pre-cooling), and then flash-frozen directly at -32℃ for 2.5 hours until the core temperature dropped to -22℃. The tubers were then stored in a -12℃ cold storage for 6 months. After thawing and processing, the tubers were found to be soft, rotten, and severely browned.

[0073] Comparative Example 3

[0074] Konjac tubers of the same specifications as in Example 1 were selected, washed, and diced into 20mm×20mm pieces using a dicing machine. A color-protecting solution was prepared by mixing 0.3% citric acid, 0.2% sodium ascorbate, and the remainder deionized water, and the tubers were soaked for 26 minutes. The gradient pre-cooling process was the same as in Example 1. Subsequently, the tubes were quick-frozen at -35℃ for 2.5 hours until the core temperature dropped to -22℃. They were then stored at -12℃ for 6 months and processed after thawing.

[0075] Comparative Example 4

[0076] Konjac tubers of the same specifications as in Example 1 were selected, washed, and diced into 20mm×20mm pieces using a dicing machine. The compound color protection and gradient pre-cooling processes were the same as in Example 1. The tubers were quick-frozen at -35℃ and a wind speed of 5m / s for 2.5 hours, and the core temperature was reduced to -22℃. They were then stored at -12℃ for 6 months. After thawing, the tubers were processed, but some cells were damaged due to the single quick-freezing process.

[0077] Comparative Example 5

[0078] Konjac tubers of the same specifications as in Example 1 were selected, washed, and diced into 20mm×20mm pieces using a dicing machine. A color-protecting solution was prepared by mixing 0.3% citric acid, 0.2% sodium ascorbate, 0.8% trehalose, and the remainder being deionized water. The tubers were soaked for 26 minutes, and all other parameters and steps were the same as in Example 1. The tubes were then processed after thawing.

[0079] Example 6

[0080] The performance of the konjac obtained in Examples 1-5 and Comparative Examples 1-5 was tested using the following methods: browning degree (ΔE) was measured using a colorimeter, with fresh konjac corms as a control; the smaller the ΔE value, the lower the degree of browning; texture (hardness, elasticity) was measured using a texture analyzer with a P / 50 probe and a testing speed of 1 mm / s; glucomannan retention rate was determined using the phenol-sulfuric acid method; and juice loss rate was the ratio of the weight difference before and after thawing to the weight before thawing. The results are shown in Table 1.

[0081] Table 1. Performance test results of konjac obtained in Examples 1-5 and Comparative Examples 1-5

[0082] Storage period (months) Browning degree (ΔE) Hardness (g) elasticity Glucomannan retention rate (%) Juice loss rate (%) Example 1 6 3.2 385 0.82 92.3 4.2 Example 2 7 3.4 372 0.80 89.7 4.8 Example 3 8 3.1 390 0.83 93.1 4.0 Example 4 7 3.5 365 0.79 89.5 4.9 Example 5 8 3.3 380 0.81 92.0 4.5 Comparative Example 1 6 8.6 295 0.65 78.5 none Comparative Example 2 6 9.2 280 0.62 75.3 18.5 Comparative Example 3 6 6.8 320 0.70 82.1 12.3 Comparative Example 4 6 3.3 345 0.76 88.2 6.5 Comparative Example 5 6 4.8 340 0.75 86.2 8.3

[0083] As shown in Table 1, the present invention, through the process coupling design of composite color protection, gradient precooling, segmented quick-freezing-frozen storage and low-temperature slow thawing, presents significant technical advantages compared with the comparative example: the browning degree (ΔE) is controlled at 3.1~3.5, with good color protection effect; the texture index is better, with hardness maintained at 372~390g and elasticity at 0.79~0.83, effectively preserving the natural texture of konjac corms.

[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for freezing and preserving fresh konjac fruit, characterized in that, Includes the following steps: 1) Raw material pretreatment; 2) Immerse the pretreated konjac blanks obtained in step 1) in the color-protecting solution, rinse, and drain. 3) Place the konjac blanks after color protection in step 2) into a pre-cooling device for gradient pre-cooling. First, pre-cool at 8~10℃, then lower to 0~4℃, so that the center temperature of the konjac blanks is stably reduced to 6~7℃. 4) Place the pre-cooled konjac blanks from step 3) into a tunnel-type quick-freezing machine for segmented quick-freezing. In the first stage, quick-freeze at -32℃ to a surface temperature of -10℃. In the second stage, quick-freeze at -35℃ to a core temperature of -28℃ to -18℃. After constant temperature freezing treatment, store the konjac blanks. 5) The frozen konjac blanks preserved in step 4) are subjected to low-temperature slow thawing treatment for subsequent konjac product processing.

2. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 1), the raw material pretreatment process is as follows: Select konjac tubers with uniform maturity and no damage or mold, remove the fibrous roots and surface mud, rinse with 0.1~0.2MPa high-pressure spray water 3~5 times, place in a sterile environment to drain until there are no visible water droplets on the surface, and process into blocks of (5~50)mm×(5~50)mm or strips of (5~20)mm×(20~200)mm by a strip cutter or dicing machine to obtain pretreated konjac blanks.

3. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 2), the color-protecting solution consists of 0.3% citric acid, 0.2% sodium ascorbate, 0.8% trehalose, 0.05% xanthan gum, and the remainder deionized water by weight percentage.

4. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 2), the soaking time is 25-30 minutes, and the mixture is stirred every 6 minutes. During the soaking process, the color-protecting liquid completely covers the konjac blank.

5. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 3), the temperature switching time for gradient precooling is 30 minutes, and the temperature fluctuation of the center of the konjac blank after precooling is ≤0.5℃.

6. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 3), the temperature is first pre-cooled at 8~10℃ for 30 minutes, and then lowered to 0~4℃ for 1 hour.

7. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 4), the wind speed for the first stage of quick-freezing is 4 m / s, and the wind speed for the second stage of quick-freezing is 5 m / s.

8. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 4), the first stage of quick-freezing takes 1.5 hours, and the second stage of quick-freezing takes 1 hour.

9. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 4), the constant temperature freezing temperature is -18℃ to -5℃, and the relative humidity is 90% to 95%.

10. The method for freezing and preserving fresh konjac fruit according to claim 1, characterized in that, In step 5), the low-temperature slow thawing process is as follows: the frozen konjac blank is placed in a refrigerated environment at 4°C and 85-90% humidity for 10 hours to thaw until the core temperature rises to 0-2°C.