Fresh-keeping method of fresh-cut square bamboo shoots
Through blanching, color protection liquid treatment, vacuum drying and low-temperature treatment, the problem of square bamboo shoots is solved, long-term freshness and crispy taste is achieved, and natural preservatives are used to ensure human health and safety.
Patent Information
- Application Number
- CN202510241757.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-03
- Publication Date
- 2025-05-13
AI Technical Summary
The prior art is difficult to keep square bamboo shoots fresh for a long time while maintaining their crispy taste, and commonly used chemical synthetic preservatives are harmful to human health.
A method including bleaching, color protection liquid treatment, vacuum drying and low temperature treatment is adopted. Specific steps include: blanching treatment to expand the pores of bamboo shoots, color protection liquid treatment uses tea polyphenols, phytic acid, VC, citric acid and other natural preservatives, vacuum drying to form a porous structure, and low temperature treatment to further reduce pores and prevent color protection liquid from flowing out.
It realizes the long-term freshness of square bamboo shoots, while maintaining their crispy taste, and uses natural preservatives, which are less harmful to the human body.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of food preservation, and particularly relates to a method for preserving fresh-cut square bamboo shoots. Background Art
[0002] Square bamboo shoots are pure natural health food, which contains 12% protein, 0.4% fat, 8% crude fiber, and is also rich in amino acids, calcium, iron, selenium, zinc and other trace elements and vitamins B1, B2, C, etc. Eating them helps the gastrointestinal motility and digestion, and achieves the special effects of weight loss, beauty, and prevention and treatment of gastrointestinal and cardiovascular diseases.
[0003] The production period of square bamboo shoots is only in specific periods of spring and autumn, and they need to be picked in time. In addition, the output is also large, making it difficult for a single area to consume them completely in a short period of time. They need to be stored or transported to farther places for sale and consumption. Under the action of microorganisms and oxidation, square bamboo shoots will deteriorate over time. Therefore, before storage and transportation, the picked square bamboo shoots need to be promptly treated for preservation and freshness. The most common treatment methods currently include quick freezing, preservative treatment and direct drying. Among the above methods, it is difficult for the square bamboo shoots to maintain their crispy taste after quick freezing, and they may even be frozen. In the preservative treatment method, people mainly use chemical synthetic preservatives to preserve stored fruits and vegetables. Although the preservation and antiseptic effects are good, many chemical synthetic substances have certain adverse effects on human health. The direct drying treatment method will also cause the square bamboo shoots to lose their crispy taste. Summary of the invention
[0004] To solve the above problems, the purpose of the present invention is to provide a method for preserving fresh-cut bamboo shoots which can keep bamboo shoots fresh for a long time while maintaining their crispy taste and has little harm to human body.
[0005] The purpose of the present invention is achieved through the following technical solutions: A method for preserving fresh-cut bamboo shoots comprises the following steps: S1. Raw material preparation: Select fresh square bamboo shoots, peel them, cut them into pieces with a thickness of 0.5-3cm, and then clean them for later use.
[0006] S2. Blanching: Put the cut bamboo shoots into a boiling water bath or steam for 3-5 minutes to expand the pores of the bamboo shoots.
[0007] S3. Cooling: After blanching, the bamboo shoots are cooled to room temperature using running water.
[0008] S4. Color-protecting liquid treatment: The bamboo shoots cooled to room temperature are treated with a color-protecting liquid; the color-protecting liquid is made of tea polyphenols, phytic acid, VC, citric acid and water, uses natural preservatives, and is harmless to the human body.
[0009] S5. Packaging: The square bamboo shoots treated with the color-protecting liquid are vacuum-treated in a vacuum bag made of PET or PE.
[0010] S6. Refrigeration: The packaged fresh-cut bamboo shoots are placed in a storage room at a temperature of 8-10°C for 1-3 hours, after which the temperature of the controlled atmosphere storage room is adjusted to 2-5°C for continued refrigeration.
[0011] Furthermore, the processing of step S4 includes: S41. Prepare color protection liquid: separately take tea polyphenols, phytic acid, VC, citric acid and water and mix them into color protection liquid. In the color protection liquid, the mass fraction of tea polyphenols is 0.5-1.5%, the mass fraction of phytic acid is 1.5%, the mass fraction of VC is 0.5-2%, the mass fraction of citric acid is 1-2%, and the rest is water.
[0012] S42. Primary dehydration: Place the square bamboo shoots cooled to room temperature in a vacuum drying oven, evacuate and dry them, remove the free water in the square bamboo shoots, and obtain porous square bamboo shoots. At the same time, the gas extracted from the vacuum drying oven is condensed into condensed water by a condenser, and then collected for later use. The condensed water contains the free water in the square bamboo shoots and a variety of volatile substances. The loss of these volatile substances will also affect the flavor of the square bamboo shoots to a certain extent. Various heating and drying methods under normal pressure will cause a certain degree of loss in color, fragrance, taste and nutritional components of the materials due to heating. The vacuum drying method, because it is isolated from the air under negative pressure, allows some materials that are prone to chemical changes such as oxidation during the drying process to better maintain their original characteristics, thereby reducing the loss of quality. After vacuum drying, the free water of the square bamboo shoots is removed, and the square bamboo shoots become a porous structure.
[0013] S43. Soaking in color-preserving liquid: Soak the dehydrated square bamboo shoots in the color-preserving liquid for 10-20 minutes. After soaking, use convection air to dry the moisture. During the soaking process, the porous square bamboo shoots quickly absorb the color-preserving liquid, which penetrates into the interior of the square bamboo shoots, thus effectively and long-term preserving and preserving the square bamboo shoots.
[0014] S44. Secondary dehydration: Place the bamboo shoots soaked in the color-protecting liquid into a vacuum drying oven, evacuate and dry them, remove the free water in the bamboo shoots again, and retain the effective ingredients in the color-protecting liquid in the bamboo shoots. The absorption of the color-protecting liquid will reduce the flavor of the bamboo shoots to a certain extent. The water in the color-protecting liquid is removed through secondary dehydration, and the effective substances (tea polyphenols, phytic acid, VC and citric acid) in it are retained. The role of the water in the color-protecting liquid is to bring the effective substances in the color-protecting liquid into the interior of the bamboo shoots.
[0015] S45. Spraying and soaking: spray water evenly onto the square bamboo shoots after secondary dehydration. During the spraying process, flatten the square bamboo shoots and turn them over for spraying. During the spraying process, the square bamboo shoots also quickly absorb condensed water and reabsorb the volatile substances contained in the condensed water back into the square bamboo shoots. After the spraying is completed, put the square bamboo shoots into a sealed container, pressurize the container to 0.2-0.5Mpa, maintain for 5-15min, then release the pressure several times until it drops to 0.1Mpa, with each pressure release of 0.03-0.06mpa, and an interval of 60-120s between two adjacent pressure releases. After the pressure release is completed (through the steps to stimulate the aroma of the square bamboo shoots and make it more intense), open the container and inject ice water to cover the square bamboo shoots (reduce the pores of the square bamboo shoots), soak the square bamboo shoots for 5-10min, take them out and use convection air to dry the moisture.
[0016] S46. Low temperature treatment: Place the square bamboo shoots treated in step S45 in a freezing room at a temperature of -15°C to -10°C for 10-20 minutes and then take them out to further reduce the pores of the square bamboo shoots and prevent the color protection liquid and spray water in the pores from flowing out.
[0017] Furthermore, in the color protection liquid in step S41, the mass fraction of tea polyphenols is 1.2%, the mass fraction of phytic acid is 1.5%, the mass fraction of VC is 1.5%, the mass fraction of citric acid is 1.6%, and the rest is water.
[0018] Furthermore, in step S43, the Chinese bamboo shoots are immersed in the color-protecting liquid for 15 minutes.
[0019] Furthermore, the spray water in step S45 is obtained by mixing bamboo shoot powder and condensed water collected in step S42 in a weight ratio of 1:(50-70). The bamboo shoot powder can enter the pores of the square bamboo shoots along with the water in step S45 to seal the pores and prevent the color protection liquid and the spray water in the pores from flowing out, and can also replenish the flavor lost during the preservation process of the square bamboo shoots and can release volatile substances for a long time to maintain the flavor of the square bamboo shoots.
[0020] Furthermore, the spray water in step S5 is obtained by mixing bamboo shoot powder and condensed water collected in step S42 in a weight ratio of 1:50.
[0021] Furthermore, the bamboo shoot skin powder is a powder obtained by drying and grinding the bamboo shoot skin.
[0022] Furthermore, the fineness of the bamboo shoot powder is 100 mesh.
[0023] Furthermore, in step S3, the temperature of the flowing water decreases step by step, and the temperature of the flowing water decreases from an initial 80-90° C. to 25-30° C. in multiple steps.
[0024] Furthermore, the step of cooling the square bamboo shoots to room temperature with running water is as follows: cooling the blanched square bamboo shoots with running water at 85°C for 2-5 minutes, then cooling with running water at 75°C, and then replacing the running water with a temperature lowered by 10°C every 5-10 minutes until the running water temperature drops to 25°C. When the temperature of the square bamboo shoots drops to 20°C, cooling is stopped, the square bamboo shoots are taken out, drained and set aside for subsequent processing. The stepwise decrease in temperature is to maintain the pores of the square bamboo shoots in an expanded state, which is convenient for subsequent color protection liquid treatment.
[0025] The preservation method of the invention can preserve the bamboo shoots for a long time, with a strong aroma and crisp taste, and uses natural preservatives, which has little harm to human body. DETAILED DESCRIPTION
[0026] The following is an explanation of the implementation of the present invention by specific specific embodiments. People familiar with the technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1
[0027] The present embodiment provides a method for preserving fresh-cut bamboo shoots, characterized in that it comprises the following steps: A method for preserving fresh-cut bamboo shoots comprises the following steps: S1. Raw material preparation: Select fresh square bamboo shoots, peel them, cut them into pieces with a thickness of 0.5-3cm, and then clean them for later use.
[0028] S2. Blanching: Put the cut bamboo shoots into boiling water bath or steam for 3-5 minutes.
[0029] S3. Cooling: After blanching, cool the square bamboo shoots to room temperature using running water. The specific steps of cooling using running water are: cool the blanched square bamboo shoots with running water at 85°C for 3 minutes, then cool them with running water at 75°C, and then cool the square bamboo shoots with running water that is 10°C lower every 8 minutes until the running water temperature drops to 25°C. When the temperature of the square bamboo shoots drops to 20°C, stop cooling, remove the square bamboo shoots, drain the water and set aside for subsequent processing.
[0030] S4. Color protection liquid treatment: The bamboo shoots cooled to room temperature were treated with color protection liquid; the color protection liquid was made of tea polyphenols, phytic acid, VC, citric acid and water; the specific steps of color protection liquid treatment are as follows: S41. Prepare color protection liquid: separately take tea polyphenols, phytic acid, VC, citric acid and water and mix them into color protection liquid. In the color protection liquid, the mass fraction of tea polyphenols is 0.6%, the mass fraction of phytic acid is 0.7%, the mass fraction of VC is 0.7%, the mass fraction of citric acid is 0.8%, and the rest is water.
[0031] S42. Primary dehydration: The square bamboo shoots cooled to room temperature are placed in a vacuum drying oven, evacuated for vacuum drying, and free water in the square bamboo shoots is removed to obtain porous square bamboo shoots. At the same time, the gas extracted from the vacuum drying oven is condensed into condensed water by a condenser and collected for later use.
[0032] S43. Soaking in color-protecting liquid: Soak the dehydrated bamboo shoots in the color-protecting liquid for 15 minutes. After soaking, use convection air to dry the water.
[0033] S44. Secondary dehydration: putting the square bamboo shoots soaked in the color protection liquid into a vacuum drying oven, evacuating the air for vacuum drying, and again removing the free water in the square bamboo shoots, leaving the effective ingredients in the color protection liquid in the square bamboo shoots.
[0034] S45. Spraying and soaking: spray the spray water evenly onto the square bamboo shoots after secondary dehydration. Flatten the square bamboo shoots during the spraying process, and turn the square bamboo shoots over for spraying. After the spraying is completed, put the square bamboo shoots into a closed container, pressurize the container to 0.3Mpa, and keep it for 10 minutes. Then release the pressure four times, each time by 0.05mpa, and the interval between two adjacent pressure releases is 90s. After the pressure release is completed, open the container and inject ice water (water temperature 0-2℃) to cover the square bamboo shoots. After soaking the square bamboo shoots for 8 minutes, take them out and use convection air to dry the water; the spray water is obtained by mixing the bamboo shoot powder and the condensed water collected in step S42 in a weight ratio of 1:50. The bamboo shoot powder is a powder obtained by drying and grinding the bamboo shoots, and the fineness of the bamboo shoot powder is 100 mesh.
[0035] S46. Low temperature treatment: Place the square bamboo shoots treated in step S45 in a freezing room at a temperature of -15°C to -10°C for 10-20 minutes and then take them out.
[0036] S5. Packaging: The square bamboo shoots treated with the color-protecting liquid are vacuum-treated in a vacuum bag made of PET or PE.
[0037] S6. Refrigeration: Store the packaged fresh-cut bamboo shoots in a 10°C atmosphere for 2 hours, then adjust the temperature of the controlled atmosphere storage to 5°C and continue refrigeration. Example 2
[0038] The difference between this embodiment and embodiment 1 is that: In the color protection liquid of step S41, the mass fraction of tea polyphenols is 1.2%, the mass fraction of phytic acid is 1.5%, the mass fraction of VC is 1.5%, the mass fraction of citric acid is 1.6%, and the rest is water. Example 3
[0039] The difference between this embodiment and embodiment 1 is that: In the color protection liquid of step S41, the mass fraction of tea polyphenols is 1.5%, the mass fraction of phytic acid is 2%, the mass fraction of VC is 2%, the mass fraction of citric acid is 2.1%, and the rest is water. Example 4
[0040] The difference between this embodiment and embodiment 1 is that: In the color protection liquid of step S41, the mass fraction of tea polyphenols is 2%, the mass fraction of phytic acid is 3%, the mass fraction of VC is 3%, the mass fraction of citric acid is 3.2%, and the rest is water. Comparative Example 1:
[0041] The difference between Comparative Example 1 and Example 2 is that Comparative Example 1 does not include step S42 and steps S44-S46 in step S4 of Example 2, and the other steps are consistent with Example 2. Comparative Example 2:
[0042] The difference between Comparative Example 2 and Example 2 is that Comparative Example 2 does not include steps S44-S46 in step S4 of Example 2, and the other steps are consistent with Example 2. Comparative Example 3:
[0043] The difference between Comparative Example 3 and Example 2 is that Comparative Example 2 does not include step S45 in step S4 of Example 2, and the other steps are consistent with Example 2. Comparative Example 4:
[0044] The difference between Comparative Example 4 and Example 2 is that Comparative Example 3 does not include steps S2-S4 in Example 2, and the other steps are consistent with Example 2. Verification experiment:
[0045] The square bamboo shoots obtained by the treatment of Examples 1-5 and Comparative Examples 1-3 were divided into 6 groups, numbered 1-8, each group including 200 bags of square bamboo shoots of equal amount, and the five groups of square bamboo shoots were placed in a refrigerated room at 8°C; wherein, No. 1 was treated by the method described in Example 1.
[0046] No. 2 was processed using the method described in Example 2.
[0047] No. 3 was treated using the method described in Example 3.
[0048] No. 4 was treated by the method described in Example 4.
[0049] No. 5 was treated by the method described in Comparative Example 1.
[0050] No. 6 was treated by the method described in Comparative Example 2.
[0051] No. 7 was processed using the method described in Comparative Example 3.
[0052] No. 8 was processed using the method described in Comparative Example 4.
[0053] Afterwards, on the 14th, 21st, 28th, 35th and 42nd days of refrigeration, 10 bags of square bamboo shoots were randomly selected from each group, and the color, hardness and odor of the square bamboo shoots in each group were observed and recorded, as shown in Table 1.
[0054] Table 1. Color, texture and aroma of bamboo shoots during storage
[0055] In Table 1: The symbol "C" indicates that all the bamboo shoots are normal in color and pure white; the symbol "C-" indicates that 10-20% of the bamboo shoots are black; and the symbol "C--" indicates that 30-50% of the bamboo shoots are black.
[0056] The symbol "H" indicates that all the bamboo shoots have a normal texture, hard and crisp; the symbol "H-" indicates that 10-20% of the bamboo shoots have become soft; the symbol "H--" indicates that 30-50% of the bamboo shoots have become soft.
[0057] The symbol "S" indicates that all bamboo shoots have a normal smell; the symbol "S+" indicates that 40-60% of the bamboo shoots have a strong fragrance, and the others are normal; the symbol "S++" indicates that more than 70% of the bamboo shoots have a strong fragrance, and the others are normal; the symbol "S-" indicates that the smell of 10-20% of the bamboo shoots has become lighter; the symbol "S--" indicates that the smell of 30-50% of the bamboo shoots has changed.
[0058] The symbol "X" means that more than 50% of the product has deteriorated (turned black, soft or had a different taste), and recording should be stopped.
[0059] According to the data analysis in Table 1, the analysis results are as follows: 1. Analysis of color retention ability (C index): The example groups (No. 1-4) were able to maintain normal color (C) within 42 days, and only Example 1 showed slight blackening (C-) within 42 days.
[0060] The control group (No. 5-8) began to generally turn black from the 14th day, among which: No. 8 (28 days X) deteriorated the fastest; No. 5 (21 days C--) deteriorated the most seriously; Comparison between the embodiments: Embodiment 2 (No. 2) performed best (maintaining C throughout the process).
[0061] 2. Analysis from the perspective of texture retention effect (H index): The embodiment groups (No. 1-4) maintained H throughout the whole process (except No. 1 which showed H- on day 42).
[0062] The comparative groups (No. 5-8) began to soften (H-) from the 14th day, among which: comparative example 1 (No. 5) showed H- on the 21st day; comparative example 3 (No. 7) showed H- on the 28th day; Comparison among the embodiments: The hardness of embodiments 2, 3 and 4 remains the most stable.
[0063] 3. Analysis from the odor change characteristics (S index): The embodiment groups (No. 1-4) generally showed an enhanced odor phenomenon (S+ to S++); Example 2 (No. 2) reached S++ in 21 days; and Example 4 (No. 4) had the latest odor improvement (35 days S+).
[0064] The comparative groups (No. 5-8) showed obvious odor deterioration (S- to S-); Comparative Example 5 showed S- in 21 days; Comparative Example 8 reached S- in 21 days.
[0065] 4. Comprehensive shelf life assessment: The embodiment groups (No. 1-4) can all maintain 42 days without corruption (no X mark) The shelf life of the comparative group (No. 5-8) was significantly shortened: In the comparative example 1 / 4, X appeared at 35 days / 28 days respectively; Comparative Examples 2 / 3 still had records at 42 days but the quality was seriously degraded.
[0066] 5. Analysis of the best treatment plan: Example 2 (No. 2) has the best overall performance. After 42 days of refrigeration, Group No. 2 can still maintain white color (C), crisp texture (H) and rich aroma (S++), which is significantly better than other groups. Example 2 can achieve 42 days of freshness preservation (traditional methods are usually <14 days), meeting the needs of long-distance cold chain transportation, and the S++ level aroma enhancement (more than 70% of bamboo shoots have rich aroma) can create a high-end product positioning.
[0067] Therefore, the concentration of the color protection liquid is controlled at: 1.2% tea polyphenols + 1.5% phytic acid + 1.5% VC + 1.6% citric acid as the optimal ratio: too low a concentration of the color protection liquid (Example 1) leads to a decrease in the color protection effect in the later stage; too high a concentration of the color protection liquid (Examples 3-4) may cause osmotic pressure imbalance or component antagonism, which in turn reduces the preservation efficiency.
[0068] 6. Analysis of the mechanism of treatment effect differences: (1) Vacuum dehydration (S42+S44) can significantly improve the color protection effect: The preservation ability of comparative example 1 (no dehydration) and comparative example 2 (only one dehydration) was significantly reduced; The double dehydration forms a porous structure, which promotes the penetration and retention of color-protecting ingredients.
[0069] (2) Synergistic effect of gradient cooling (S3) and pressurized immersion (S45): Gradual cooling reduces cell damage caused by thermal shock; the pressurization-depressurization process promotes deep penetration of bamboo shoot powder (containing natural antibacterial ingredients) and condensed water.
[0070] (3) Low temperature treatment (S46) and packaging (S5) Quick freezing inhibits enzyme activity, and vacuum packaging blocks oxygen, which together delays browning and spoilage.
[0071] (4) Analysis of the causes of proportional failure
[0072] In summary, after comparing and analyzing Examples 1-4 and Comparative Examples 1-4, it can be seen that the solution of Example 2 of the present application is the best, and the solution of Example 3 is second best.
[0073] Other aspects of the present invention that are not described in detail are all conventional techniques known to those skilled in the art.
[0074] It should be noted that the terms "comprises", "includes" or any other variations are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.
[0075] The protection scope of the present invention is not limited to the technical solutions disclosed in the specific implementation methods. Any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.
Claims
1. A method for preserving fresh-cut bamboo shoots, characterized in that: The following steps are involved: S1. Raw material preparation: Select fresh bamboo shoots, peel and cut into pieces with a thickness of 0.5-3 cm, then clean and set aside; S2. Blanching: Put the cut bamboo shoots into boiling water or steam for 3-5 minutes; S3. Cooling: After blanching, the bamboo shoots were cooled to room temperature using running water; S4 color protection liquid treatment: The bamboo shoots were cooled to room temperature and treated with color protection liquid; the color protection liquid is made of tea polyphenols, phytic acid, VC, citric acid and water; S5. Packaging: vacuum-treat the bamboo shoots treated with the color-protecting liquid using a vacuum bag made of PET or PE; S6. Refrigeration: The packaged fresh-cut bamboo shoots are placed in a storage room at a temperature of 8-10°C for 1-3 hours, after which the temperature of the controlled atmosphere storage room is adjusted to 2-5°C for continued refrigeration.
2. A method for preserving fresh-cut bamboo shoots according to claim 1, characterized in that: The processing of step S4 includes: S41. Modulating color protection liquid: tea polyphenols, phytic acid, VC, citric acid and water are mixed to prepare color protection liquid, wherein the mass fraction of tea polyphenols is 0.5-1.5%, the mass fraction of phytic acid is 1.5%, the mass fraction of VC is 0.5-2%, the mass fraction of citric acid is 1-2%, and the rest is water; S42. A dehydration: The bamboo shoots cooled to room temperature were placed in a vacuum drying oven, vacuumed and dried to remove the free water in the bamboo shoots to obtain porous bamboo shoots, and the gas extracted from the vacuum drying oven was condensed into condensed water by a condenser and collected for later use; S43 color protection liquid soaking: the first dehydrated bamboo shoots into the color protection liquid soaked 10-20min, after soaking using convection air to dry the water; S44. Secondary dehydration: The bamboo shoots soaked in color protection solution were placed in a vacuum drying oven, vacuumed and dried, and the free water in the bamboo shoots was removed again, leaving the effective ingredients in the color protection solution in the bamboo shoots; S45. Spraying and soaking: spraying water evenly onto the square bamboo shoots after secondary dehydration, flattening the square bamboo shoots during the spraying process, and turning the square bamboo shoots over for spraying. After the spraying is completed, the square bamboo shoots are placed in a closed container, pressurized to 0.2-0.5Mpa, maintained for 5-15min, and then repeatedly depressurized until it drops to 0.1Mpa, 0.03-0.06mpa each time, with an interval of 60-120s between two adjacent depressurizations. After the depressurization is completed, open the container and inject ice water to cover the square bamboo shoots, soak the square bamboo shoots for 5-10min, remove them and use convection air to dry the water; S46. Low temperature treatment: Place the square bamboo shoots treated in step S45 in a freezing room at a temperature of -15°C to -10°C for 10-20 minutes and then take them out.
3. A method for preserving fresh-cut bamboo shoots according to claim 2, characterized in that: In the color protection liquid of step S41, the mass fraction of tea polyphenols is 1.2%, the mass fraction of phytic acid is 1.5%, the mass fraction of VC is 1.5%, the mass fraction of citric acid is 1.6%, and the rest is water.
4. A method for preserving fresh-cut bamboo shoots according to claim 2, characterized in that: In step S43, the Chinese bamboo shoots are immersed in the color-protecting liquid for 15 minutes.
5. A method for preserving fresh-cut bamboo shoots according to claim 2, characterized in that: The spray water in step S45 is obtained by mixing bamboo shoot powder and condensed water collected in step S42 in a weight ratio of 1: (50-70).
6. A method for preserving fresh-cut bamboo shoots according to claim 5, characterized in that: The spray water in step S5 is obtained by mixing bamboo shoot powder and condensed water collected in step S42 in a weight ratio of 1:
50.
7. A method for preserving fresh-cut bamboo shoots according to claim 5 or 6, characterized in that: The bamboo shoot skin powder is a powder obtained by drying and grinding the bamboo shoot skin.
8. A method for preserving fresh-cut bamboo shoots according to claim 7, characterized in that: The fineness of the bamboo shoot powder is 100 meshes.
9. A method for preserving fresh-cut bamboo shoots according to claim 1, characterized in that: In step S3, the temperature of the running water decreases step by step, and the running water temperature decreases from the initial 80-90° C. to 25-30° C. in multiple steps.
10. A method for preserving fresh-cut bamboo shoots according to claim 9, characterized in that The steps of cooling the square bamboo shoots to room temperature with running water are as follows: cool the blanched square bamboo shoots with running water at 85°C for 2-5 minutes, then cool them with running water at 75°C, and then replace the running water with a temperature lowered by 10°C every 5-10 minutes until the running water temperature drops to 25°C. When the temperature of the square bamboo shoots drops to 20°C, stop cooling, remove the square bamboo shoots, drain the water and set aside for subsequent processing.