Quick-frozen crisp-keeping bamboo shoots and production process thereof

Abstract

The invention discloses quick-frozen crisp-keeping bamboo shoots and a production process thereof, and the process comprises the following steps: firstly shelling picked bamboo shoots, bleaching and boiling after shelling, adding a treating agent acetic acid in the bleaching and boiling process, carrying out fixation on the bleached and boiled bamboo shoots, adding a crisp-keeping agent calcium lactate in the fixation process, rapidly peeling the bamboo shoots after the fixation is finished, and carrying out vacuum drying on the bamboo shoots, so as to obtain the quick-frozen crisp-keeping bamboo shoots. Quickly cooling and soaking the peeled bamboo shoots in a crisp-keeping agent tannic acid solution, pre-cooling the soaked bamboo shoots, and quickly freezing the pre-cooled bamboo shoots until the surface temperature of the bamboo shoots is less than-35 DEG C; according to the quick-frozen bamboo shoot preparation method disclosed by the invention, treatment is carried out through the treating agent and the composite brittleness-keeping agent, and the brittleness of the quick-frozen bamboo shoots after being unfrozen is fully kept through a synergistic reaction between the brittleness-keeping agent tannic acid and calcium lactate, so that the quick-frozen bamboo shoots keep the brittleness taste of fresh bamboo shoots, and the quick-frozen bamboo shoot preparation method has outstanding application and popularization prospects.

Description

Technical Field

[0001] The present invention relates to the field of food preparation, and particularly to a quick-frozen crispy bamboo shoots and its production process. Background Art

[0002] As the young stem of plants in the Bambusoideae subfamily of the Poaceae family, the edible part of bamboo shoots has a water content of 90 - 92% and a crude fiber content of 1.5 - 2.8%, and is rich in umami amino acids such as aspartic acid and glutamic acid. The unique arrangement structure of palisade cells gives it a relatively high natural crispness value. However, this cell wall network composed of pectin - cellulose - hemicellulose is extremely sensitive to temperature changes.

[0003] As a characteristic vegetable with high dietary fiber and low calories, the fresh and crispy taste of bamboo shoots is an important edible quality index. However, there are the following technical bottlenecks in the quick-freezing process: 1. Cell structure damage mechanism: The ice crystals generated during the freezing process will pierce the cell wall, and the loss of water in the cell gap after thawing leads to the collapse of the tissue structure; 2. Pectin degradation problem: In the traditional blanching process, high temperature causes the hydrolysis of protopectin into soluble pectin, losing the bonding function between cells; in the prior art, conventional calcium chloride treatment can only maintain the basic crispness and cannot reach a crispness recovery rate of more than 90% of fresh bamboo shoots.

[0004] According to the 2024 China Quick-Frozen Vegetable Industry Report, the market scale of quick-frozen bamboo shoots has reached 2.36 billion yuan, but the problem of "soft texture" accounts for 31.7% in consumer complaints. Market research shows that the general crispness retention period of current quick-frozen bamboo shoot products is less than 3 months, and the taste score drops by more than 40% compared with fresh bamboo shoots. Existing patented technologies can extend the crispness retention period to 5 months through compound phosphate treatment, but there is a risk of heavy metal residues; there is an urgent need to develop a new crispness preservation technology that can stably maintain the cell skeleton structure, so that the crispness of quick-frozen bamboo shoots after thawing is fully retained, and the crispness taste of fresh bamboo shoots can be achieved for quick-frozen bamboo shoots, which is of great significance for improving the added value of quick-frozen bamboo shoot products. Summary of the Invention

[0005] The object of the present invention is to overcome the shortcomings of the prior art and provide a quick-frozen and crispness-preserved bamboo shoot and its production process. The process is to first shell the picked bamboo shoots, then blanch them after shelling, add the treatment agent acetic acid during the blanching process, carry out heat inactivation on the blanched bamboo shoots, add the crispness-preserving agent calcium lactate during the heat inactivation process, quickly carry out the de-covering treatment on the bamboo shoots after the heat inactivation is completed, quickly cool and soak the de-covered bamboo shoots in a tannic acid solution of the crispness-preserving agent, carry out pre-cooling treatment on the soaked bamboo shoots, and quickly freeze them to a surface temperature of less than -35°C after pre-cooling; thus, the preparation of the quick-frozen bamboo shoots is completed. Through the treatment with the treatment agent and the composite crispness-preserving agent, and through the synergistic reaction between the crispness-preserving agents tannic acid and calcium lactate, the crispness of the quick-frozen bamboo shoots after thawing is fully retained, achieving that the quick-frozen bamboo shoots retain the crispness and taste of fresh bamboo shoots, and having prominent application and promotion prospects.

[0006] To achieve the above technical effects, the following technical solutions are adopted: A production process for quick-frozen and crispness-preserved bamboo shoots, comprising the following steps: Step (1): Bamboo shoot picking and selection: Pick bamboo shoots 10 - 20 cm long and shell them; select bamboo shoots without pests and with a light yellow color, and transport them to the treatment point for blanching and heat inactivation treatment within two hours. Step (2): Blanching: Place the bamboo shoots in boiling water at 100°C with added acetic acid and blanch for 5 - 10 minutes. The concentration of the acetic acid is 2wt% - 3wt%; the mass of the blanching water is 2 - 3 times the mass of the bamboo shoots. Step (3): Heat inactivation: Quickly transfer the blanched bamboo shoots to a pre-boiled heat inactivation pot. The pre-boiled water in the heat inactivation pot contains the crispness-preserving agent calcium lactate, and the concentration of the calcium lactate is 0.5wt% - 2wt%; the mass of the boiling water for heat inactivation is 4 - 5 times the mass of the bamboo shoots; the pressure in the heat inactivation pot is 0.1 - 0.2 MPa, and the heat inactivation time is 10 - 30 minutes; quickly fish out the bamboo shoots after heat inactivation and carry out the de-covering treatment. Step (4): De-covering treatment: Place the bamboo shoots fished out after heat inactivation in a bamboo shoot de-covering device for de-covering, and keep the de-covered bamboo shoots at 60°C or above. Step (5): Cooling and introducing the crispness-preserving agent tannic acid: Introduce the de-covered bamboo shoots into the crispness-preserving agent solution to cool to 20 - 25°C, soak for 10 - 30 minutes, then fish out and cut off the old ends, and then rinse with circulating clear water for 5 - 10 min; the crispness-preserving agent solution is a 1wt% - 3wt% tannic acid solution, and its temperature is 0 - 5°C. Step (6): Pre-cooling: Immerse the rinsed bamboo shoots in ice water for 5 - 10 min to complete pre-cooling. Step (7): Packaging: Package the pre-cooled bamboo shoots according to the specification of 0.5 - 2 kg / bag, and the packaging is carried out in a packaging room at -2°C to 2°C. Step (8): Quick-freezing: The packaged bamboo shoots enter the liquid nitrogen quick-freezing tunnel through a conveyor belt for quick-freezing at a temperature of -80 to -100 °C; the time is 20 - 30 minutes to exit the tunnel. Step (9): Refrigeration: Place the quick-frozen bamboo shoots in a cold storage room at a temperature of -18 °C to -20 °C for storage.

[0007] Furthermore, in the step (1), the bamboo shoots are white bamboo shoots, arhat bamboo shoots, bitter bamboo shoots or bamboo shoots of Phyllostachys nigra var. henonis.

[0008] Furthermore, in the step (2), blanching is carried out for 8 minutes, the concentration of acetic acid is 2.5 wt%; the mass of the blanching water is 2 times the mass of the bamboo shoots.

[0009] Furthermore, in the step (3), the concentration of calcium lactate is 1 wt%; the mass of the boiling water for fixing the color is 4 times the mass of the bamboo shoots.

[0010] Furthermore, in the step (3), the pressure in the fixing color pot is 0.2 MPa and the fixing color time is 20 minutes.

[0011] Furthermore, in the step (4), the bamboo shoots after peeling are kept at 65 °C.

[0012] Furthermore, in the step (5), it is cooled to 20 °C, soaked for 20 minutes, and rinsed with circulating clear water for 5 minutes.

[0013] Furthermore, in the step (5), the crispness-preserving agent solution is a 2 wt% tannic acid solution and its temperature is 2 °C.

[0014] A kind of quick-frozen and crispness-preserved bamboo shoots is prepared by the preparation method of any one of the above.

[0015] The beneficial effects of the present invention are: The present invention discloses a quick-frozen and crispness-preserved bamboo shoot and its production process. The process is as follows: after the picked bamboo shoots are shelled, they are blanched, and acetic acid as a treatment agent is added during the blanching process. After blanching, the bamboo shoots are subjected to heat inactivation, and calcium lactate as a crispness-preserving agent is added during the heat inactivation process. After the heat inactivation is completed, the bamboo shoots are quickly subjected to the peeling treatment. The peeled bamboo shoots are quickly cooled and soaked in a tannic acid solution as a crispness-preserving agent. After soaking, the bamboo shoots are pre-cooled and then quickly frozen until the surface temperature of the bamboo shoots is less than -35°C; thus, the preparation of the quick-frozen bamboo shoots is completed. The present invention is treated with a treatment agent and a composite crispness-preserving agent. After the treatment agent acetic acid enters the bamboo shoot body, it effectively prevents the carboxyl dissociation on the pectin in the bamboo shoot body, reduces the hydration of pectin, is conducive to the combination between pectins and the formation of a three-dimensional network structure, and lays a foundation for the combination of the subsequent crispness-preserving agent. During the heat inactivation process, after calcium ions enter the bamboo shoots, pectic acid can combine with calcium ions to form insoluble pectate salts. These salts form a rigid support structure by filling the cell gaps, enhance the tissue compactness, and keep the bamboo shoots brittle. After the bamboo shoots are peeled, they are cooled with a tannic acid solution as a crispness-preserving agent. The temperature of the tannic acid solution as a crispness-preserving agent is relatively low, and the temperature of the just-peeled bamboo shoots is above 60°C. Due to thermal expansion and contraction, after the bamboo shoots come into contact with the tannic acid solution as a crispness-preserving agent, tannic acid in the crispness-preserving agent solution quickly enters the interior of the bamboo shoots. The phenolic hydroxyl groups in the tannic acid that enter the interior of the bamboo shoots undergo complexation reactions with calcium ions and other ions, generating stable elastic gel substances, directly enhancing the bonding strength between cells. The phenolic hydroxyl groups in tannic acid can also combine and crosslink with the cellulose on the cell wall and the alcohol hydroxyl groups in pectin through hydrogen bonding, significantly improving the mechanical strength of the cell wall; the above reactions synergistically improve the crispness of the quick-frozen bamboo shoot product, greatly enhancing the strength of the supporting substances between cells, significantly improving the crispness of the quick-frozen bamboo shoots, and achieving a taste comparable to that of fresh bamboo shoots. And due to the sharp change in temperature, the surface of the bamboo shoots shrinks, locking the tannic acid and calcium lactate as crispness-preserving agents inside the bamboo shoots, making the effect of the crispness-preserving agent greater and the crispness-preserving effect of the bamboo shoots better. It has outstanding application and promotion prospects. Detailed Embodiments

[0016] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with 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.

[0017] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0018] It should be noted that the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, and / or combinations thereof.

[0019] Example 1: This example relates to a quick-frozen and crisp-preserved bamboo shoot and its production process: Step (1): Bamboo shoot picking and selection: Pick bamboo shoots 10 - 20 cm long and remove the shells; Select bamboo shoots without pests and with a light yellow color, and transport them to the treatment point within two hours for blanching and de-enzyming treatment; The bamboo shoots are white bamboo shoots.

[0020] Step (2): Blanching: Place the bamboo shoots in boiling water at 100 °C with acetic acid added and blanch for 5 minutes. The concentration of the acetic acid is 2 wt%; The mass of the blanching water is twice the mass of the bamboo shoots; Step (3): De-enzyming: Quickly transfer the blanched bamboo shoots to a pre-boiled de-enzyming pot. The pre-boiled water in the de-enzyming pot contains the crisp-preserving agent calcium lactate, and the concentration of the calcium lactate is 0.5 wt%; The mass of the de-enzyming boiling water is four times the mass of the bamboo shoots; The pressure in the de-enzyming pot is 0.1 MPa, and the de-enzyming time is 10 minutes; After de-enzyming, quickly fish out and perform the peeling treatment; Step (4): Peeling treatment: Place the bamboo shoots fished out after de-enzyming in a bamboo shoot peeling device for peeling, and the peeled bamboo shoots are maintained at 60 °C; Step (5): Cooling and introducing the crisp-preserving agent tannic acid: Introduce the peeled bamboo shoots into the crisp-preserving agent solution and cool to 20 °C, soak for 10 minutes, then fish out and cut off the old ends, and then rinse with circulating clear water for 5 min; The crisp-preserving agent solution is a 1 wt% tannic acid solution, and its temperature is 0 °C; Step (6): Pre-cooling: Immerse the rinsed bamboo shoots in ice water for 5 minutes to complete pre-cooling; Step (7): Packaging: Package the pre-cooled bamboo shoots according to the specification of 0.5 - 2 kg / bag, and the packaging is carried out in a packaging room at -2 °C to 2 °C; Step (8): Quick-freezing: Transfer the packaged bamboo shoots into a liquid nitrogen quick-freezing tunnel through a conveyor belt for quick-freezing. The temperature is -80; It takes 20 minutes to exit the tunnel; Step (9): Cold storage: Place the quick-frozen bamboo shoots in a cold storage room at -18 °C for storage.

[0021] Obtain the quick-frozen bamboo shoot 1 described in Example 1.

[0022] Example 2: This embodiment relates to a quick-frozen and crisp-preserved bamboo shoot and its production process: Step (1): Bamboo shoot picking and selection: Pick bamboo shoots 10 - 20 cm long and remove their shells; Select bamboo shoots without pests and with a light yellow color, and transport them to the treatment point within two hours for blanching and deactivation treatment; The bamboo shoots are bitter bamboo shoots.

[0023] Step (2): Blanching: Place the bamboo shoots in boiling water at 100 °C with acetic acid added and blanch for 10 minutes. The concentration of the acetic acid is 3 wt%; The mass of the blanching water is 3 times the mass of the bamboo shoots; Step (3): Deactivation: Quickly transfer the blanched bamboo shoots to a pre-boiled deactivation pot. The pre-boiled water in the deactivation pot contains the crisp-preserving agent calcium lactate, and the concentration of the calcium lactate is 2 wt%; The mass of the deactivation boiling water is 5 times the mass of the bamboo shoots; The pressure in the deactivation pot is 0.2 MPa, and the deactivation time is 30 minutes; After deactivation, quickly fish out and perform the peeling treatment; Step (4): Peeling treatment: Place the bamboo shoots fished out after deactivation in a bamboo shoot peeling device for peeling. The peeled bamboo shoots are maintained at 65 °C; Step (5): Cooling and introducing the crisp-preserving agent tannic acid: Introduce the peeled bamboo shoots into the crisp-preserving agent solution and cool to 25 °C, soak for 30 minutes, then fish out and cut off the old ends, and then rinse with circulating clear water for 10 min; The crisp-preserving agent solution is a 3 wt% tannic acid solution, and its temperature is 5 °C; Step (6): Pre-cooling: Immerse the rinsed bamboo shoots in ice water for 10 min to complete pre-cooling; Step (7): Packaging: Package the pre-cooled bamboo shoots according to the specification of 0.5 - 2 kg / bag. The packaging is carried out in a packaging room at -2 °C to 2 °C; Step (8): Quick-freezing: Transfer the packaged bamboo shoots into a liquid nitrogen quick-freezing tunnel through a conveyor belt for quick-freezing. The temperature is -100 °C; It takes 30 minutes to exit the tunnel; Step (9): Cold storage: Place the quick-frozen bamboo shoots in a cold storage room at -20 °C for storage.

[0024] Obtain the quick-frozen bamboo shoots 2 described in Example 2.

[0025] Example 3: This embodiment relates to a quick-frozen and crisp-preserved bamboo shoot and its production process: Step (1): Bamboo shoot picking and selection: Pick bamboo shoots 10 - 20 cm long and remove their shells; Select bamboo shoots without pests and with a light yellow color, and transport them to the treatment point within two hours for blanching and deactivation treatment; The bamboo shoots are Buddha belly bamboo shoots.

[0026] Step (2): Blanching: Place the bamboo shoots in boiling water at 100 °C with acetic acid added. The concentration of the acetic acid is 2.5 wt%. The mass of the blanching water is twice that of the bamboo shoots, and blanch for 8 minutes. Step (3): Fixing the green color: Quickly transfer the blanched bamboo shoots to a pre-boiled fixing pot. The pre-boiled water in the fixing pot contains calcium lactate as a crispness preservative. The concentration of the calcium lactate is 1 wt%. The mass of the boiling water for fixing is four times that of the bamboo shoots. The pressure in the fixing pot is 0.2 MPa, and the fixing time is 20 minutes. After fixing, quickly take out and perform the peeling treatment. Step (4): Peeling treatment: Place the bamboo shoots taken out after fixing in a bamboo shoot peeling device for peeling. The peeled bamboo shoots are maintained at 65 °C. Step (5): Cooling and introducing tannic acid as a crispness preservative: Introduce the peeled bamboo shoots into a crispness preservative solution and cool to 20 °C, soak for 20 minutes, then take out and cut off the old ends, and then rinse with circulating clear water for 5 minutes. The crispness preservative solution is a 2 wt% tannic acid solution, and its temperature is 2 °C. Step (6): Pre-cooling: Immerse the rinsed bamboo shoots in ice water for 10 minutes to complete pre-cooling. Step (7): Packaging: Package the pre-cooled bamboo shoots in specifications of 0.5 - 2 kg / bag. The packaging is carried out in a packaging room at -2 °C to 2 °C. Step (8): Quick freezing: Convey the packaged bamboo shoots through a conveyor belt into a liquid nitrogen quick-freezing tunnel for quick freezing. The temperature is -80 °C, and it takes 25 minutes to exit the tunnel. Step (9): Cold storage: Place the quick-frozen bamboo shoots in a cold storage room at -20 °C for storage.

[0027] Obtain the quick-frozen bamboo shoots 3 described in Example 3.

[0028] Comparative Example 1: This comparative example relates to a quick-frozen and crispness-preserved bamboo shoot and its production process. Based on Example 3, do not add two kinds of crispness preservatives: Step (1): Bamboo shoot picking and selection: Pick bamboo shoots 10 - 20 cm long and remove the shells. Select bamboo shoots without pests and with a light yellow color, and transport them to the processing point for blanching and fixing treatment within two hours. The bamboo shoots are Buddha Belly bamboo shoots.

[0029] Step (2): Blanching: Place the bamboo shoots in boiling water at 100 °C with acetic acid added. The concentration of the acetic acid is 2.5 wt%. The mass of the blanching water is twice that of the bamboo shoots, and blanch for 8 minutes. Step (3): Blanching: Quickly transfer the blanched bamboo shoots to a pre-boiled blanching pot. The pre-boiled water in the blanching pot does not contain calcium lactate as a crispness retainer (concentration is 0 wt%), and the mass of the blanching boiling water is 4 times that of the bamboo shoots. The pressure in the blanching pot is 0.2 MPa, and the blanching time is 20 minutes. After blanching, quickly fish out and perform peeling treatment. Step (4): Peeling treatment: Place the bamboo shoots fished out after blanching in a bamboo shoot peeling device for peeling. The peeled bamboo shoots are maintained at 65 °C. Step (5): Cooling: Transfer the peeled bamboo shoots into clear water and cool them to 20 °C, soak for 20 minutes, then fish out and cut off the old ends, and then rinse with circulating clear water for 5 min. The temperature of the clear water is 2 °C. Step (6): Pre-cooling: Immerse the rinsed bamboo shoots in ice water for 10 min to complete pre-cooling. Step (7): Packaging: Package the pre-cooled bamboo shoots according to the specification of 0.5 - 2 kg / bag. The packaging is carried out in a packaging room at -2 °C to 2 °C. Step (8): Quick-freezing: Transfer the packaged bamboo shoots into a liquid nitrogen quick-freezing tunnel through a conveyor belt for quick-freezing. The temperature is -80 °C, and it takes 25 minutes to exit the tunnel. Step (9): Cold storage: Place the quick-frozen bamboo shoots in a cold storage room at -20 °C for storage.

[0030] Obtain the quick-frozen bamboo shoots 4 described in Comparative Example 1.

[0031] Comparative Example 2: This example relates to a quick-frozen crispness-retained bamboo shoot and its production process. Based on Example 3, only calcium lactate as a crispness retainer is added: Step (1): Bamboo shoot picking and selection: Pick bamboo shoots 10 - 20 cm long and remove the shells. Select bamboo shoots without pests and with a light yellow color, and transport them to the processing point for blanching and blanching treatment within two hours. The bamboo shoots are Phyllostachys aurea bamboo shoots.

[0032] Step (2): Blanching: Place the bamboo shoots in boiling water at 100 °C with acetic acid added and blanch for 8 minutes. The concentration of the acetic acid is 2.5 wt%. The mass of the blanching water is 2 times that of the bamboo shoots. Step (3): Blanching: Quickly transfer the blanched bamboo shoots to a pre-boiled blanching pot. The pre-boiled water in the blanching pot contains calcium lactate as a crispness retainer, and the concentration of the calcium lactate is 1 wt%. The mass of the blanching boiling water is 4 times that of the bamboo shoots. The pressure in the blanching pot is 0.2 MPa, and the blanching time is 20 minutes. After blanching, quickly fish out and perform peeling treatment. Step (4): Peeling treatment: Place the bamboo shoots fished out after blanching in a bamboo shoot peeling device for peeling. The peeled bamboo shoots are maintained at 65 °C. Step (5): Cooling: Immerse the shelled bamboo shoots in clear water and cool them to 20°C, soak for 20 minutes, then take them out, cut off the old ends, and rinse with circulating clear water for 5 minutes; the temperature of the clear water is 2°C; Step (6): Pre-cooling: Immerse the rinsed bamboo shoots in ice water for 10 minutes to complete pre-cooling; Step (7): Packaging: Package the pre-cooled bamboo shoots in the specification of 0.5 - 2 kg / bag, and the packaging is carried out in a packaging room at -2°C to 2°C; Step (8): Quick-freezing: Convey the packaged bamboo shoots into a liquid nitrogen quick-freezing tunnel through a conveyor belt for quick-freezing, the temperature is -80°C; it takes 25 minutes to leave the tunnel; Step (9): Cold storage: Put the quick-frozen bamboo shoots into a cold storage at -20°C for preservation.

[0033] Obtain the quick-frozen bamboo shoots 5 as described in Comparative Example 2.

[0034] Comparative Example 3: This example relates to a quick-frozen and crisp-preserved bamboo shoot and its production process: Based on Example 3, only add the crisp-preserving agent tannic acid: Step (1): Bamboo shoot picking and selection: Pick bamboo shoots 10 - 20 cm long and remove the shells; select bamboo shoots without pests and with a light yellow color, and transport them to the treatment point for blanching and de-enzyming within two hours; the bamboo shoots are Bambusa ventricosa McClure bamboo shoots.

[0035] Step (2): Blanching: Place the bamboo shoots in boiling water at 100°C with added acetic acid for 8 minutes, the concentration of the acetic acid is 2.5 wt%; the mass of the blanching water is 2 times the mass of the bamboo shoots; Step (3): De-enzyming: Quickly transfer the blanched bamboo shoots to a pre-boiled de-enzyming pot. The pre-boiled water in the de-enzyming pot does not contain the crisp-preserving agent calcium lactate (concentration is 0 wt%), the mass of the de-enzyming boiling water is 4 times the mass of the bamboo shoots; the pressure in the de-enzyming pot is 0.2 MPa, and the de-enzyming time is 20 minutes; quickly take them out and carry out shelling treatment after de-enzyming; Step (4): Shelling treatment: Place the bamboo shoots taken out after de-enzyming in a bamboo shoot shelling device for shelling, and the shelled bamboo shoots are kept at 65°C; Step (5): Cooling and introducing the crisp-preserving agent tannic acid: Immerse the shelled bamboo shoots in the crisp-preserving agent solution and cool them to 20°C, soak for 20 minutes, then take them out, cut off the old ends, and rinse with circulating clear water for 5 minutes; the crisp-preserving agent solution is a 2 wt% tannic acid solution, and its temperature is 2°C; Step (6): Pre-cooling: Immerse the rinsed bamboo shoots in ice water for 10 minutes to complete pre-cooling; Step (7): Packaging: The pre-cooled bamboo shoots are packaged in specifications of 0.5 - 2 kg / bag in a packaging room at -2°C to 2°C. Step (8): Quick freezing: The packaged bamboo shoots enter a liquid nitrogen quick-freezing tunnel through a conveyor belt for quick freezing at a temperature of -80°C and come out of the tunnel after 25 minutes. Step (9): Refrigeration: The quick-frozen bamboo shoots are stored in a cold storage room at a temperature of -20°C.

[0036] Obtain the quick-frozen bamboo shoots 6 described in Comparative Example 3.

[0037] Perform a brittleness test on the quick-frozen bamboo shoots in the above Examples 1 - 3 and Comparative Examples 1 - 3. First, immediately test the brittleness of the quick-frozen bamboo shoots in Examples 1 - 3 and Comparative Examples 1 - 3 after they are completely thawed. Use a texture analyzer (Brookfield CT3, USA) to test the breaking force of the thawed bamboo shoots in the TPA Test mode, and use the TexturePro CT software to export the brittleness parameters. During the test, use a fixture to prevent the bamboo shoots from slipping sideways, and select the same position for testing (the thickness of the bamboo shoot slices is 10 mm). Test 20 samples for each example or comparative example and take the average value. The results are shown in Table 1: Table 1 Comparison of the brittleness of the quick-frozen bamboo shoots thawed in Examples 1 - 3 and Comparative Examples 1 - 3

[0038] Therefore, in summary, the present invention discloses a quick-frozen and crispness-preserved bamboo shoot and its production process. The process is as follows: after harvesting the bamboo shoots, remove the shells. After shelling, blanch the bamboo shoots, and add the treatment agent acetic acid during the blanching process. After blanching, carry out the de-enzyming process on the bamboo shoots, and add the crispness-preserving agent calcium lactate during the de-enzyming process. After the de-enzyming is completed, quickly carry out the peeling process on the bamboo shoots. After peeling, quickly cool and soak the bamboo shoots in a tannic acid solution of the crispness-preserving agent. After soaking, carry out the precooling process on the bamboo shoots. After precooling, quickly freeze the bamboo shoots until the surface temperature of the bamboo shoots is less than -35°C; thus, the preparation of the quick-frozen bamboo shoots is completed. The present invention is processed by a treatment agent and a composite crispness-preserving agent. After the treatment agent acetic acid enters the bamboo shoot body, it effectively prevents the carboxyl group on the pectin in the bamboo shoot body from dissociating. The hydration of pectin is reduced, which is beneficial to the combination between pectins and the formation of a three-dimensional network structure, laying a foundation for the combination of the subsequent crispness-preserving agent. During the de-enzyming process, after calcium ions enter the bamboo shoots, pectic acid can combine with calcium ions to form insoluble pectate salts. These salts form a rigid support structure by filling the cell gaps, enhancing the tissue compactness and keeping the bamboo shoots brittle. After the bamboo shoots are peeled, they are cooled with a tannic acid solution of the crispness-preserving agent. The temperature of the tannic acid solution of the crispness-preserving agent is relatively low, and the temperature of the just-peeled bamboo shoots is above 60°C. Due to thermal expansion and contraction, after the bamboo shoots come into contact with the tannic acid solution of the crispness-preserving agent, tannic acid in the crispness-preserving agent solution quickly enters the interior of the bamboo shoots. The phenolic hydroxyl groups in the tannic acid that enter the interior of the bamboo shoots undergo complexation reactions with calcium ions and other ions to generate stable elastic gel substances, directly enhancing the bonding strength between cells. The phenolic hydroxyl groups in tannic acid can also combine and crosslink with the cellulose on the cell wall and the alcohol hydroxyl groups in pectin through hydrogen bonding to significantly enhance the mechanical strength of the cell wall; the above reactions synergistically improve the crispness of the quick-frozen bamboo shoot product, greatly enhancing the strength of the supporting substances between cells, significantly improving the crispness of the quick-frozen bamboo shoots, and achieving a taste comparable to that of fresh bamboo shoots. And due to the rapid change in temperature, the surface of the bamboo shoots shrinks, locking the tannic acid and calcium lactate of the crispness-preserving agent inside the bamboo shoots, making the effect of the crispness-preserving agent greater and the crispness-preserving effect of the bamboo shoots better. It has prominent application and promotion prospects.

[0039] At this point, those skilled in the art recognize that although the embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived from the disclosed content of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and determined to cover all these other variations or modifications.

Claims

1. A production process for quick-frozen and crispness-preserved bamboo shoots, characterized in that, The production process includes the following steps: Step (1): Bamboo shoot picking and selection: Pick bamboo shoots 10 - 20 cm long and remove their shells; Select bamboo shoots without pests and with a light yellow color, and transport them to the processing point within two hours for blanching and deactivation treatment; Step (2): Blanching: Place the bamboo shoots in boiling water at 100 °C with acetic acid added and blanch for 5 - 10 minutes. The concentration of the acetic acid is 2wt% - 3wt%; The mass of the blanching water is 2 - 3 times the mass of the bamboo shoots; Step (3): Deactivation: Quickly transfer the blanched bamboo shoots to a pre-boiled deactivation pot. The pre-boiled water in the deactivation pot contains the crispness-preserving agent calcium lactate, and the concentration of the calcium lactate is 0.5wt% - 2wt%; The mass of the deactivation boiling water is 4 - 5 times the mass of the bamboo shoots; The pressure in the deactivation pot is 0.1 - 0.2 MPa, and the deactivation time is 10 - 30 minutes; After deactivation, quickly fish out and perform the peeling treatment; Step (4): Peeling treatment: Place the bamboo shoots fished out after deactivation in a bamboo shoot peeling device for peeling. The peeled bamboo shoots are kept at 60 °C or above; Step (5): Cooling and introducing the crispness-preserving agent tannic acid: Introduce the peeled bamboo shoots into the crispness-preserving agent solution and cool to 20 - 25 °C, soak for 10 - 30 minutes, then fish out and cut off the old ends, and then rinse with circulating clear water for 5 - 10 min; The crispness-preserving agent solution is a 1wt% - 3wt% tannic acid solution, and its temperature is 0 - 5 °C; Step (6): Pre-cooling: Immerse the rinsed bamboo shoots in ice water for 5 - 10 min to complete pre-cooling; Step (7): Packaging: Package the pre-cooled bamboo shoots according to the specification of 0.5 - 2 kg / bag. The packaging is carried out in a packaging room at -2 °C - 2 °C; Step (8): Quick-freezing: Transfer the packaged bamboo shoots into a liquid nitrogen quick-freezing tunnel through a conveyor belt for quick-freezing. The temperature is -80 - 100 °C; It takes 20 - 30 min to exit the tunnel; Step (9): Cold storage: Place the quick-frozen bamboo shoots in a cold storage room at -18 °C - 20 °C for storage.

2. The production process of quick-frozen crispy bamboo shoots as described in claim 1, characterized in that, The bamboo shoots in the step (1) are white bamboo shoots, arhat bamboo shoots, bitter bamboo shoots or fan bamboo shoots.

3. A quick-frozen and crispness-preserved bamboo shoot production process as described in claim 1, characterized in that, In the step (2), blanch for 8 minutes, the concentration of the acetic acid is 2.5wt%; The mass of the blanching water is 2 times the mass of the bamboo shoots.

4. A production process for quick-frozen crispy bamboo shoots as described in claim 1, characterized in that, In the step (3), the concentration of the calcium lactate is 1wt%; The mass of the deactivation boiling water is 4 times the mass of the bamboo shoots.

5. A quick-frozen and crispness-preserved bamboo shoot production process as described in claim 1, characterized in that, In the step (3), the pressure in the deactivation pot is 0.2 MPa, and the deactivation time is 20 minutes.

6. The production process of quick-frozen and crispness-preserved bamboo shoots as described in claim 1, characterized in that, In the step (4), the peeled bamboo shoots are kept at 65 °C.

7. The production process of quick-frozen and crispness-preserved bamboo shoots as described in claim 1, characterized in that, In the step (5), cool to 20 °C, soak for 20 minutes, and rinse with circulating clear water for 5 min.

8. A quick-frozen and crispness-preserved bamboo shoot production process as described in claim 1, characterized in that, In the step (5), the crispness-preserving agent solution is a 2wt% tannic acid solution, and its temperature is 2 °C.

9. A quick-frozen and crispness-preserved bamboo shoot, characterized in that, The quick-frozen and crispness-preserved bamboo shoots are prepared by the preparation method according to any one of claims 1 - 8.

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