Method for preparing cabbages through cooperation of ultrasonic alkali liquor pretreatment and vacuum freeze drying

Abstract

The invention provides a method for preparing cabbages through cooperation of ultrasonic alkali liquor pretreatment and vacuum freeze drying. The method for preparing Chinese cabbages through cooperation of ultrasonic alkali liquor pretreatment and vacuum freeze drying comprises the following steps: 1, selecting Chinese cabbages: selecting fresh Chinese cabbages which are free of diseases and insect pests and good in texture, and avoiding selection of parts which have obvious mechanical damage and are yellow and withered; 2, cleaning the cabbages: washing the selected cabbages with flowing clear water to remove soil, dust, part of residual pesticides and other impurities on the surfaces of the cabbages; according to the method for preparing the cabbages through cooperation of ultrasonic alkali liquor pretreatment and vacuum freeze drying, impurities and pesticide residues on the surfaces of the cabbages can be effectively removed through ultrasonic alkali liquor pretreatment, meanwhile, cell walls of the cabbages are damaged to a certain degree, the subsequent vacuum freeze drying process is facilitated, and the drying efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of food processing, in particular to a method for preparing cabbage by ultrasonic alkali solution pretreatment coordinated with vacuum freeze drying. Background Art

[0002] Cabbage, also known as Brassica oleracea, is an herbaceous plant of the genus Brassica in the family Cruciferae. Cabbage is short and stout, with fleshy, unbranched stems that are green or gray-green; there are many basal leaves, which are thick and wrapped in layers to form a sphere, milky white or light green; the basal leaves and lower stem leaves are oblong-obovate or round, with petioles with broad wings, and the upper lotus leaves are ovate or oblong, and the base is amplexicaul; the inflorescence is terminal or axillary, the sepals are erect, narrow and oblong, the petals are light yellow, wide and long obovate or nearly round; the fruit is cylindrical, slightly flattened on both sides, and the beak is conical. Cabbage is a common vegetable, rich in vitamins, dietary fiber and other nutrients.

[0003] At present, the common cabbage processing methods include air drying and hot air drying, but these methods often lead to the loss of nutrients, large changes in color, and poor taste of cabbage. Although vacuum freeze-drying technology can better preserve the nutrition and quality of food, when used alone, the drying efficiency is low and the effect of removing impurities and pesticide residues on the surface of cabbage is limited.

[0004] Therefore, it is necessary to provide a method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying to solve the above technical problems. Summary of the invention

[0005] The invention provides a method for preparing cabbage by ultrasonic alkali solution pretreatment in coordination with vacuum freeze drying, which solves the problems in the background technology.

[0006] In order to solve the above technical problems, the method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying provided by the present invention comprises the following steps:

[0007] Step 1: Choose cabbage: Choose fresh cabbage that is free of pests and diseases and has good texture. Avoid choosing cabbage that has obvious mechanical damage or is yellow and withered.

[0008] Step 2: Wash the cabbage: Rinse the selected cabbage with running water to remove dirt, dust, and some residual pesticides and other impurities on the surface;

[0009] Step 3: Preparation of lye solution: Prepare lye solution of appropriate concentration according to the amount of cabbage and pretreatment requirements, and use an appropriate amount of distilled water or deionized water to dissolve the alkali powder. Stir appropriately during the dissolution process to accelerate the dissolution and ensure a uniform solution.

[0010] Step 4: Ultrasonic treatment: Place the cleaned cabbage into the prepared lye solution, making sure that the cabbage is completely immersed in the lye solution, and place the container containing the cabbage and the lye solution into the ultrasonic equipment;

[0011] Step 5: Cleaning: After the ultrasonic treatment, take the cabbage out of the alkali solution and then rinse it with plenty of clean water;

[0012] Step 6. Pre-freeze: Drain the washed cabbage. You can use clean gauze or kitchen paper towels to gently absorb excess water on the surface of the cabbage, and then put the cabbage into the freezer;

[0013] Step 7: Vacuum drying: quickly transfer the pre-frozen cabbage into the drying chamber of the vacuum freeze dryer for drying;

[0014] Step 8. Post-processing: After drying, when the pressure of the vacuum freeze dryer returns to normal pressure, open the door to take out the cabbage and package the dried cabbage.

[0015] Preferably, in the second step, the cabbage is rinsed with running water and then cut into pieces or four pieces to facilitate subsequent processing.

[0016] Preferably, the alkali solution in the third step is sodium carbonate solution or sodium bicarbonate solution.

[0017] Preferably, the concentration of the alkali solution is controlled between 0.5% and 2%.

[0018] Preferably, during the dissolution process in the third step, the stirring rate is 80-200 r / min and the stirring time is 5-10 min.

[0019] Preferably, in the fourth step of ensuring that the cabbage is completely immersed in the alkali solution, a plastic basket or a clamp can be used to fix the cabbage in a suitable position in the alkali solution.

[0020] Preferably, the frequency of the ultrasonic equipment in the fourth step is set at 20-40 kHz, and the processing time is 10-30 min.

[0021] Preferably, the rinsing time of the cabbage in the fifth step is 5-10 minutes, until the pH value of the water after rinsing is close to neutral, pH=6.5-7.5, to ensure that the alkali solution remaining on the surface and inside of the cabbage is completely washed away.

[0022] Preferably, the freezing equipment in the sixth step is a vacuum freeze dryer or a freezer, the temperature is set to -30°C--40°C, and the pre-freezing time is 2-4 hours, so that the water inside the cabbage is frozen into ice crystals.

[0023] Preferably, in the seventh step, the vacuum degree of the vacuum freeze dryer is set to 10-100 Pa, the shelf temperature is -20°C-0°C, and the drying time is 12-36 hours.

[0024] Compared with the related art, the method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying provided by the present invention has the following beneficial effects:

[0025] The present invention provides a method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying. The present invention can effectively remove impurities and pesticide residues on the surface of cabbage through ultrasonic alkali solution pretreatment, and at the same time destroy the cell wall of cabbage to a certain extent, which is beneficial to the subsequent vacuum freeze drying process and improves the drying efficiency. The vacuum freeze drying technology can retain the nutritional components, color and flavor of cabbage to the greatest extent, avoiding the problems caused by traditional drying methods, and the method is simple to operate and easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention provides a schematic flow chart of a preferred embodiment of the method for preparing cabbage by ultrasonic alkali solution pretreatment in conjunction with vacuum freeze drying. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0028] Please refer to Figure 1 ,in, Figure 1 The present invention provides a schematic flow chart of a preferred embodiment of the method for preparing cabbage by ultrasonic alkali solution pretreatment in conjunction with vacuum freeze drying.

[0029] Example 1

[0030] The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying comprises the following steps:

[0031] Step 1: Choose cabbage: Choose fresh cabbage that is free of pests and diseases and has good texture. Avoid choosing cabbage that has obvious mechanical damage or is yellow and withered.

[0032] Step 2: Wash the cabbage: Rinse the selected cabbage with running water to remove dirt, dust and some residual pesticides and other impurities on the surface. After rinsing the cabbage, cut it into pieces or four pieces for easy subsequent processing;

[0033] Step 3, alkali solution preparation: according to the amount of cabbage and pretreatment requirements, prepare alkali solution of appropriate concentration, use appropriate amount of distilled water or deionized water to dissolve alkali powder, alkali solution uses sodium carbonate solution or sodium bicarbonate solution, the concentration of alkali solution is controlled between 0.5%, and it can be properly stirred during the dissolution process, the stirring rate is 80r / min, the stirring time is 5min, to accelerate the dissolution and ensure the uniformity of the solution;

[0034] Step 4: Ultrasonic treatment: Put the cleaned cabbage into the prepared alkali solution. You can use a plastic basket or clamp to fix the cabbage in a suitable position in the alkali solution to ensure that the cabbage is completely immersed in the alkali solution. Put the container containing the cabbage and alkali solution into the ultrasonic equipment. The frequency of the ultrasonic equipment is set at 20kHz and the treatment time is 10 minutes.

[0035] Step 5: Cleaning: After the ultrasonic treatment, take the cabbage out of the alkali solution and rinse it with plenty of clean water for 5-10 minutes until the pH value of the rinsed water is close to neutral, pH = 6.5-7.5, ensuring that the alkali solution remaining on the surface and inside of the cabbage is completely washed away;

[0036] Step 6: Pre-freeze: Drain the washed cabbage. You can use clean gauze or kitchen paper towels to gently absorb the excess water on the surface of the cabbage. Then put the cabbage into a freezing device, which is a vacuum freeze dryer or freezer. Set the temperature to -30℃ and pre-freeze for 2 hours to freeze the water inside the cabbage into ice crystals.

[0037] Step 7, vacuum drying: quickly transfer the pre-frozen cabbage to the drying chamber of the vacuum freeze dryer for drying. The vacuum degree of the vacuum freeze dryer is set to 10Pa, the shelf temperature is -20°C, and the drying time is 12h.

[0038] Step 8. Post-processing: After drying, when the pressure of the vacuum freeze dryer returns to normal pressure, open the door to take out the cabbage and package the dried cabbage.

[0039] Example 2

[0040] The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying comprises the following steps:

[0041] Step 1: Choose cabbage: Choose fresh cabbage that is free of pests and diseases and has good texture. Avoid choosing cabbage that has obvious mechanical damage or is yellow and withered.

[0042] Step 2: Wash the cabbage: Rinse the selected cabbage with running water to remove dirt, dust and some residual pesticides and other impurities on the surface. After rinsing the cabbage, cut it into pieces or four pieces for easy subsequent processing;

[0043] Step 3, alkali solution preparation: according to the amount of cabbage and pretreatment requirements, prepare alkali solution of appropriate concentration, use appropriate amount of distilled water or deionized water to dissolve alkali powder, alkali solution uses sodium carbonate solution or sodium bicarbonate solution, the concentration of alkali solution is controlled between 1%, and it can be properly stirred during the dissolution process, the stirring rate is 120r / min, the stirring time is 7min, to accelerate the dissolution and ensure the uniformity of the solution;

[0044] Step 4: Ultrasonic treatment: Put the cleaned cabbage into the prepared lye solution. You can use a plastic basket or clamp to fix the cabbage in a suitable position in the lye solution to ensure that the cabbage is completely immersed in the lye solution. Put the container containing the cabbage and lye solution into the ultrasonic equipment. The frequency of the ultrasonic equipment is set at 30kHz and the treatment time is 15 minutes.

[0045] Step 5: Cleaning: After the ultrasonic treatment, take the cabbage out of the alkali solution and rinse it with plenty of clean water for 5-10 minutes until the pH value of the rinsed water is close to neutral, pH = 6.5-7.5, ensuring that the alkali solution remaining on the surface and inside of the cabbage is completely washed away;

[0046] Step 6: Pre-freeze: Drain the washed cabbage. You can use clean gauze or kitchen paper towels to gently absorb the excess water on the surface of the cabbage. Then put the cabbage into a freezing device, which is a vacuum freeze dryer or freezer. Set the temperature to -32°C and pre-freeze for 2.5 hours to freeze the water inside the cabbage into ice crystals.

[0047] Step 7, vacuum drying: quickly transfer the pre-frozen cabbage to the drying chamber of the vacuum freeze dryer for drying. The vacuum degree of the vacuum freeze dryer is set to 30Pa, the shelf temperature is -15°C, and the drying time is 18h.

[0048] Step 8. Post-processing: After drying, when the pressure of the vacuum freeze dryer returns to normal pressure, open the door to take out the cabbage and package the dried cabbage.

[0049] Example 3

[0050] The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying comprises the following steps:

[0051] Step 1: Choose cabbage: Choose fresh cabbage that is free of pests and diseases and has good texture. Avoid choosing cabbage that has obvious mechanical damage or is yellow and withered.

[0052] Step 2: Wash the cabbage: Rinse the selected cabbage with running water to remove dirt, dust and some residual pesticides and other impurities on the surface. After rinsing the cabbage, cut it into pieces or four pieces for easy subsequent processing;

[0053] Step 3, alkali solution preparation: according to the amount of cabbage and pretreatment requirements, prepare alkali solution of appropriate concentration, use appropriate amount of distilled water or deionized water to dissolve alkali powder, alkali solution uses sodium carbonate solution or sodium bicarbonate solution, the concentration of alkali solution is controlled between 1.5%, and it can be properly stirred during the dissolution process, the stirring rate is 160r / min, the stirring time is 8min, to accelerate the dissolution and ensure the uniformity of the solution;

[0054] Step 4: Ultrasonic treatment: Put the cleaned cabbage into the prepared lye solution. You can use a plastic basket or clamp to fix the cabbage in a suitable position in the lye solution to ensure that the cabbage is completely immersed in the lye solution. Put the container containing the cabbage and lye solution into the ultrasonic equipment. The frequency of the ultrasonic equipment is set at 35kHz and the treatment time is 25 minutes.

[0055] Step 5: Cleaning: After the ultrasonic treatment, take the cabbage out of the alkali solution and rinse it with plenty of clean water for 5-10 minutes until the pH value of the rinsed water is close to neutral, pH = 6.5-7.5, ensuring that the alkali solution remaining on the surface and inside of the cabbage is completely washed away;

[0056] Step 6: Pre-freeze: Drain the washed cabbage. You can use clean gauze or kitchen paper towels to gently absorb the excess water on the surface of the cabbage. Then put the cabbage into a freezing device, which is a vacuum freeze dryer or freezer. Set the temperature to -35°C and pre-freeze for 3 hours to freeze the water inside the cabbage into ice crystals.

[0057] Step 7, vacuum drying: quickly transfer the pre-frozen cabbage to the drying chamber of the vacuum freeze dryer for drying. The vacuum degree of the vacuum freeze dryer is set to 60Pa, the shelf temperature is -10°C, and the drying time is 24h.

[0058] Step 8. Post-processing: After drying, when the pressure of the vacuum freeze dryer returns to normal pressure, open the door to take out the cabbage and package the dried cabbage.

[0059] Example 4

[0060] The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying comprises the following steps:

[0061] Step 1: Choose cabbage: Choose fresh cabbage that is free of pests and diseases and has good texture. Avoid choosing cabbage that has obvious mechanical damage or is yellow and withered.

[0062] Step 2: Wash the cabbage: Rinse the selected cabbage with running water to remove dirt, dust and some residual pesticides and other impurities on the surface. After rinsing the cabbage, cut it into pieces or four pieces for easy subsequent processing;

[0063] Step 3, alkali solution preparation: according to the amount of cabbage and pretreatment requirements, prepare alkali solution of appropriate concentration, use appropriate amount of distilled water or deionized water to dissolve alkali powder, alkali solution uses sodium carbonate solution or sodium bicarbonate solution, the concentration of alkali solution is controlled between 2%, and it can be properly stirred during the dissolution process, the stirring rate is 200r / min, the stirring time is 10min, to accelerate the dissolution and ensure the uniformity of the solution;

[0064] Step 4: Ultrasonic treatment: Put the cleaned cabbage into the prepared alkali solution. You can use a plastic basket or clamp to fix the cabbage in a suitable position in the alkali solution to ensure that the cabbage is completely immersed in the alkali solution. Put the container containing the cabbage and alkali solution into the ultrasonic equipment. The frequency of the ultrasonic equipment is set at 40kHz and the treatment time is 30 minutes.

[0065] Step 5: Cleaning: After the ultrasonic treatment, take the cabbage out of the alkali solution and rinse it with plenty of clean water for 5-10 minutes until the pH value of the rinsed water is close to neutral, pH = 6.5-7.5, ensuring that the alkali solution remaining on the surface and inside of the cabbage is completely washed away;

[0066] Step 6: Pre-freeze: Drain the washed cabbage. You can use clean gauze or kitchen paper towels to gently absorb the excess water on the surface of the cabbage. Then put the cabbage into a freezing device, which is a vacuum freeze dryer or freezer. Set the temperature to -40°C and pre-freeze for 4 hours to freeze the water inside the cabbage into ice crystals.

[0067] Step 7, vacuum drying: quickly transfer the pre-frozen cabbage to the drying chamber of the vacuum freeze dryer for drying. The vacuum degree of the vacuum freeze dryer is set to 100Pa, the shelf temperature is -5°C, and the drying time is 36h.

[0068] Step 8. Post-processing: After drying, when the pressure of the vacuum freeze dryer returns to normal pressure, open the door to take out the cabbage and package the dried cabbage.

[0069] The working principle of the method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying provided by the present invention is as follows:

[0070] First, select fresh, pest-free, and good-quality cabbages, and avoid those with obvious mechanical damage, yellowing, and wilting; rinse the selected cabbages with running water to remove dirt, dust, and some impurities such as residual pesticides on the surface; prepare alkali solution of appropriate concentration according to the amount of cabbage and pretreatment requirements, and use an appropriate amount of distilled water or deionized water to dissolve the alkali powder. During the dissolution process, stir appropriately to accelerate the dissolution and ensure that the solution is uniform; then put the washed cabbage into the prepared alkali solution, making sure that the cabbage is completely immersed in the alkali solution, and place the loaded Put a container with cabbage and alkali solution into an ultrasonic device; after the ultrasonic treatment is completed, take the cabbage out of the alkali solution, and then rinse the cabbage with a large amount of clean water; drain the washed cabbage, and use clean gauze or kitchen paper towels to gently absorb excess water on the surface of the cabbage, and then put the cabbage into a freezing device; quickly transfer the pre-frozen cabbage to a drying chamber of a vacuum freeze dryer for drying; after drying, when the pressure of the vacuum freeze dryer returns to normal pressure, open the chamber door to take out the cabbage, and package the dried cabbage.

[0071] Compared with the related art, the method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying provided by the present invention has the following beneficial effects:

[0072] The present invention can effectively remove impurities and pesticide residues on the surface of cabbage through ultrasonic alkali solution pretreatment, and at the same time destroy the cell wall of cabbage to a certain extent, which is beneficial to the subsequent vacuum freeze-drying process and improves the drying efficiency. The vacuum freeze-drying technology can retain the nutritional components, color and flavor of cabbage to the greatest extent, avoiding the problems caused by traditional drying methods, and the method is simple to operate and easy to realize industrial production.

[0073] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying, characterized in that: The following steps are involved: Step 1: Choose cabbage: Choose fresh cabbage that is free of pests and diseases and has good texture. Avoid choosing cabbage that has obvious mechanical damage or is yellow and withered. Step 2: Wash the cabbage: Rinse the selected cabbage with running water to remove dirt, dust, and some residual pesticides and other impurities on the surface; Step 3: Preparation of lye solution: Prepare lye solution of appropriate concentration according to the amount of cabbage and pretreatment requirements, and use an appropriate amount of distilled water or deionized water to dissolve the alkali powder. Stir appropriately during the dissolution process to accelerate the dissolution and ensure a uniform solution. Step 4: Ultrasonic treatment: Place the cleaned cabbage into the prepared lye solution, making sure that the cabbage is completely immersed in the lye solution, and place the container containing the cabbage and the lye solution into the ultrasonic equipment; Step 5: Cleaning: After the ultrasonic treatment, take the cabbage out of the alkali solution and then rinse it with plenty of clean water; Step 6. Pre-freeze: Drain the washed cabbage. You can use clean gauze or kitchen paper towels to gently absorb excess water on the surface of the cabbage, and then put the cabbage into the freezer; Step 7: Vacuum drying: quickly transfer the pre-frozen cabbage into the drying chamber of the vacuum freeze dryer for drying; Step 8. Post-processing: After drying, when the pressure of the vacuum freeze dryer returns to normal pressure, open the door to take out the cabbage and package the dried cabbage.

2. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 1, characterized in that: In the second step, the cabbage is rinsed with running water and cut into pieces or four pieces for easy subsequent processing.

3. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 1, characterized in that: The alkali solution in the third step is sodium carbonate solution or sodium bicarbonate solution.

4. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 3, characterized in that: The concentration of the alkali solution is controlled between 0.5% and 2%.

5. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 1, characterized in that: During the dissolution process in the third step, the stirring rate is 80-200 r / min and the stirring time is 5-10 min.

6. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 1, characterized in that: In the fourth step, ensuring that the cabbage is completely immersed in the lye solution can be achieved by using a plastic basket or a clamp to fix the cabbage in a suitable position in the lye solution.

7. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 1, characterized in that: In the fourth step, the frequency of the ultrasonic equipment is set at 20-40 kHz, and the treatment time is 10-30 minutes.

8. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 1, characterized in that: The rinsing time of the cabbage in the fifth step is 5-10 minutes, until the pH value of the water after rinsing is close to neutral, pH=6.5-7.5, to ensure that the alkali solution remaining on the surface and inside of the cabbage is completely washed away.

9. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 1, characterized in that: The freezing equipment in the sixth step is a vacuum freeze dryer or a freezer, the temperature is set to -30°C--40°C, and the pre-freezing time is 2-4 hours, so that the water inside the cabbage is frozen into ice crystals.

10. The method for preparing cabbage by ultrasonic alkali solution pretreatment and vacuum freeze drying according to claim 1, characterized in that: In the seventh step, the vacuum degree of the vacuum freeze dryer is set to 10-100 Pa, the shelf temperature is -20°C-0°C, and the drying time is 12-36h.

Images