Freeze-drying, dehydrating, processing and fresh-keeping method of dried ballonflower

Abstract

The invention relates to the technical field of dried ballonflower processing, and discloses a freeze-drying, dewatering, processing and fresh-keeping method of dried ballonflower, which comprises the following steps: step 1, pretreatment, step 2, fixation, step 3, dewatering and drying, and step 4, fresh-keeping. Through strict pretreatment including high-quality dried ballonflower selection and disinfection treatment, the influence of microorganisms and impurities on the quality of dried ballonflower can be reduced, and the original taste and nutrition of dried ballonflower are reserved. The enzyme activity can be effectively passivated in the enzyme deactivation link, color change, nutrition loss and texture deterioration caused by enzymatic reaction in the subsequent processing and storage process of the dried ballonflower are prevented, and the enzyme deactivation effect is further optimized by adding citric acid. The dehydrating and drying process is carried out at low temperature and low pressure, so that the nutritional ingredients and quality of the dried ballonflower are prevented from being damaged by high temperature, and the dehydrated dried ballonflower keeps good shape and quality.

Description

Technical Field

[0001] The invention relates to the technical field of Gongcai processing, in particular to a freeze-drying, dehydrating, processing and fresh-keeping method for Gongcai. Background Art

[0002] As a specialty vegetable, Gongcai has a unique taste and rich nutritional value. However, Gongcai has a high water content and is prone to rot and deterioration after picking. Its preservation and processing have always been a concern in the industry. Traditional preservation methods often fail to effectively extend the shelf life of Gongcai, and may damage the quality of Gongcai during processing, affecting its taste and nutritional content. Therefore, an efficient and high-quality Gongcai processing, dehydration, drying and preservation method is needed. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a freeze-drying and dehydrating processing and preservation method for Gongcai, which solves the problems of short shelf life and easily damaged quality in the prior Gongcai processing and preservation process, and improves the quality and shelf life of Gongcai processed products.

[0004] To achieve the above purpose, the present invention is implemented by the following technical scheme: a freeze-drying and dehydrating processing and preservation method of Gongcai, comprising the following steps:

[0005] Step 1: Preprocessing

[0006] Select fresh, pest-free, tender Gongcai, remove the roots and yellow leaves of Gongcai, keep the stems intact, and finally peel and cut into strips;

[0007] Rinse the selected Gongcai with clean water for 2-3 times, then soak it in a 0.5%-1% salt solution for 10-15 minutes for disinfection, then rinse it with clean water and drain the surface water;

[0008] Step 2: Finishing

[0009] Put the pre-treated Gongcai into hot water at a temperature of 90-95°C for 2-3 minutes, and the mass ratio of hot water to Gongcai is 5:1-6:1;

[0010] After killing the green, quickly remove the Gongcai and put it into cold water to cool to room temperature. The cold water temperature is 5-10℃.

[0011] Step 3: Dehydration and drying

[0012] Spread the cooled Gongcai evenly on a multi-layer air-permeable drying rack, with the spacing between each layer of the drying rack being 10-15 cm;

[0013] The drying rack on which the Gongcai is placed is placed in a vacuum freeze dryer, first pre-frozen at -30°C to -25°C for 2-3 hours, and then dried at a vacuum degree of 10-20 Pa and a temperature of -20°C to -15°C for 8-10 hours until the water content of the Gongcai is reduced to 5%-8%;

[0014] Step 4: Keep fresh

[0015] Take the dehydrated Gongcai out of the dryer and quickly put it into a fresh-keeping bag filled with a mixture of nitrogen and carbon dioxide under a sterile environment. The volume ratio of nitrogen to carbon dioxide is 3:2-4:1, and the oxygen permeability of the fresh-keeping bag is less than 1cm 3 / (m 2 ·24h·0.1MPa);

[0016] After sealing the fresh-keeping bag containing Gongcai, place it in a storage environment with a temperature of 5-10°C and a relative humidity of 30%-40%.

[0017] Preferably, in the pretreatment step, the length of Gongcai is 20-30 cm.

[0018] Preferably, in the fixing step, citric acid with a mass concentration of 0.1%-0.2% is added to the hot water.

[0019] Preferably, in the dehydration and drying step, the multi-layer breathable drying rack is made of food-grade stainless steel, and the diameter of the air holes is 0.5-1 mm.

[0020] Preferably, in the preservation step, the material of the fresh-keeping bag is a composite material of polyethylene and polyamide, and the thickness is 0.08-0.12 mm.

[0021] The present invention provides a freeze-drying, dehydrating, processing and preservation method for Gongcai, which has the following beneficial effects:

[0022] 1. The present invention can reduce the influence of microorganisms and impurities on the quality of Gongcai and retain the original taste and nutrition of Gongcai through strict pretreatment, including selecting high-quality Gongcai and disinfection.

[0023] 2. The withering step of the present invention can effectively inactivate enzyme activity, thereby preventing Gongcai from changing color, losing nutrients and deteriorating texture due to enzymatic reactions during subsequent processing and storage. The addition of citric acid further optimizes the withering effect.

[0024] 3. The dehydration and drying process of the present invention is carried out at low temperature and low pressure, which avoids the damage of high temperature to the nutritional components and quality of Gongcai, so that Gongcai maintains good shape and quality after dehydration.

[0025] 4. The invention can inhibit the respiration and microbial growth of Gongcai through the mixed gas of nitrogen and carbon dioxide in a specific ratio in the fresh-keeping bag, and the fresh-keeping bag with low oxygen permeability can maintain a stable gas environment. The suitable storage environment temperature and humidity work synergistically with the gas environment in the fresh-keeping bag, which can effectively extend the fresh-keeping period of Gongcai and maintain the edible value and commercial value of Gongcai.

[0026] 5. Each processing step of the present invention has clear process parameters, which is easy to operate and control, and is conducive to ensuring the stability and consistency of product quality; and the drying racks and fresh-keeping bag materials used in the processing process meet the requirements of food processing, ensuring the hygienic safety and efficiency of the Gongcai processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, 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.

[0029] Embodiment 1:

[0030] Please refer to the attached Figure 1 The embodiment of the present invention provides a freeze-drying, dehydration and preservation method for Gongcai, comprising the following steps:

[0031] Step 1: Preprocessing

[0032] Select fresh, pest-free, tender Gongcai, remove the roots and yellow leaves of Gongcai, keep the stems intact, and finally peel and cut into strips;

[0033] Rinse the selected Gongcai with clean water twice, then soak it in a 0.5% salt solution for 10 minutes for disinfection, then rinse it with clean water and drain the surface water;

[0034] In the pretreatment step, the length of Gongcai was 20 cm;

[0035] Step 2: Finishing

[0036] The pre-treated Gongcai was placed in hot water at a temperature of 90°C for 2 minutes, and the mass ratio of hot water to Gongcai was 5:1;

[0037] After killing the green, quickly remove the Gongcai and put it in cold water to cool to room temperature. The cold water temperature is 5℃.

[0038] In the fixing step, citric acid with a mass concentration of 0.1% is added to the hot water;

[0039] Step 3: Dehydration and drying

[0040] Spread the cooled Gongcai evenly on a multi-layer air-permeable drying rack, with a spacing of 10 cm between each layer of the drying rack;

[0041] The drying rack on which the Gongcai is placed is placed in a vacuum freeze dryer, first pre-frozen at -30°C for 2 hours, and then dried at a vacuum degree of 10 Pa and a temperature of -20°C for 8 hours until the water content of the Gongcai is reduced to 5%;

[0042] In the dehydration and drying step, the multi-layer breathable drying rack is made of food-grade stainless steel, and the diameter of the air holes is 0.5 mm;

[0043] Step 4: Keep fresh

[0044] The dehydrated Gongcai was taken out of the dryer and quickly placed in a fresh-keeping bag filled with a mixture of nitrogen and carbon dioxide under a sterile environment. The volume ratio of nitrogen to carbon dioxide was 3:2, and the oxygen permeability of the fresh-keeping bag was less than 1cm 3 / (m 2 ·24h·0.1MPa);

[0045] After sealing the preservation bag containing Gongcai, place it in a storage environment with a temperature of 5°C and a relative humidity of 30%;

[0046] In the preservation step, the material of the fresh-keeping bag is a composite material of polyethylene and polyamide, and the thickness is 0.08 mm.

[0047] In this embodiment, the high quality of the Gongcai raw material is ensured by carefully selecting fresh, pest-free and tender Gongcai as raw materials, and removing the roots and yellow leaves. During the pretreatment process, the impurities and microorganisms on the surface of Gongcai can be effectively removed by rinsing with clean water and soaking in a salt solution of a specific concentration for disinfection, which reduces the impact on the quality of Gongcai during the subsequent processing, so that the processed Gongcai can retain its original taste, color and nutrients to the greatest extent. The killing step uses hot water treatment within a specific temperature range and time, as well as a suitable hot water to Gongcai mass ratio, which can quickly passivate the enzyme activity in Gongcai and prevent Gongcai from causing color changes, nutrient loss and texture deterioration due to enzymatic reactions during subsequent processing and storage. Rapid cooling to room temperature after killing helps to fix the quality of Gongcai and further ensure its taste and appearance.

[0048] During the dehydration and drying step, the cooled Gongcai is evenly spread on a multi-layer breathable drying rack. The appropriate spacing between each layer of the drying rack and the food-grade stainless steel material ensure that the Gongcai is evenly heated and ventilated during the drying process, which is conducive to the smooth discharge of moisture. The specific pre-freezing temperature, time, drying vacuum degree and temperature, and drying time parameter settings in the vacuum freeze dryer can sublimate the moisture in the Gongcai under a low temperature and low pressure environment, avoiding the damage to the nutritional components and quality of the Gongcai by high temperature, so that the Gongcai maintains a good shape and quality after dehydration and drying, and the moisture content can be accurately controlled within the appropriate range of 5%-8%.

[0049] In the preservation step, the dehydrated Gongcai is placed in a fresh-keeping bag filled with a specific ratio of mixed gases. This gas combination can inhibit the respiration of Gongcai and the growth and reproduction of microorganisms. Nitrogen, as an inert gas, can reduce the oxidation of oxygen on Gongcai, and carbon dioxide can further inhibit the respiratory metabolism of Gongcai. The synergistic effect of the two creates a good fresh-keeping gas environment for Gongcai, effectively extending the shelf life of Gongcai.

[0050] The low oxygen permeability of the fresh-keeping bag can prevent external oxygen from entering the bag, maintain a stable gas environment in the bag, and further ensure the preservation effect of Gongcai.

[0051] After sealing the fresh-keeping bag containing Gongcai, place it in a storage environment with a temperature of 5°C and a relative humidity of 30%. This low-temperature and low-humidity environment can slow down the physiological activities and chemical reactions of Gongcai and reduce the growth rate of microorganisms. It cooperates with the gas environment in the fresh-keeping bag to comprehensively ensure the quality stability of Gongcai during the storage process, reduce the risk of deterioration, and enable Gongcai to maintain good edible value and commodity value for a longer period of time.

[0052] In summary, in the entire processing method, each step from pretreatment, withering, dehydration and drying to preservation has clear process parameters, such as the length range of Gongcai, concentration of salt solution, soaking time, citric acid concentration in hot water for withering, drying rack parameters, vacuum freeze-drying parameters, preservation bag materials, etc. These detailed parameters provide clear operational guidance for actual production and processing, which is easy for workers to understand and implement, and is conducive to ensuring the stability and consistency of product quality.

[0053] Food-grade stainless steel is used as the material of the multi-layer breathable drying rack to ensure the hygiene and safety of Gongcai during the processing; the fresh-keeping bags are made of a composite material of polyethylene and polyamide, which has both good gas barrier properties and appropriate strength. The selection of these materials meets the requirements of food processing and also helps to improve processing efficiency and product quality.

[0054] Embodiment 2:

[0055] Please refer to the attached Figure 1The embodiment of the present invention provides a freeze-drying, dehydration and preservation method for Gongcai, comprising the following steps:

[0056] Step 1: Preprocessing

[0057] Select fresh, pest-free, tender Gongcai, remove the roots and yellow leaves of Gongcai, keep the stems intact, and finally peel and cut into strips;

[0058] Rinse the selected Gongcai with clean water for 3 times, then soak it in a 1% salt solution for 15 minutes for disinfection, then rinse it with clean water and drain the surface water;

[0059] In the pretreatment step, the length of Gongcai was 30 cm;

[0060] Step 2: Finishing

[0061] The pre-treated Gongcai was placed in hot water at a temperature of 95°C for 3 minutes, and the mass ratio of hot water to Gongcai was 6:1;

[0062] After killing the green, quickly remove the Gongcai and put it into cold water to cool to room temperature. The cold water temperature is 10℃.

[0063] In the fixing step, citric acid with a mass concentration of 0.2% is added to the hot water;

[0064] Step 3: Dehydration and drying

[0065] Spread the cooled Gongcai evenly on a multi-layer air-permeable drying rack, with a spacing of 15 cm between each layer of the drying rack;

[0066] The drying rack on which the Gongcai is placed is placed in a vacuum freeze dryer, first pre-frozen at -25°C for 3 hours, and then dried at a vacuum degree of 20 Pa and a temperature of -15°C for 10 hours until the water content of the Gongcai is reduced to 8%;

[0067] In the dehydration and drying step, the multi-layer breathable drying rack is made of food-grade stainless steel, and the diameter of the air holes is 1 mm;

[0068] Step 4: Keep fresh

[0069] The dehydrated Gongcai was taken out of the dryer and quickly placed in a fresh-keeping bag filled with a mixture of nitrogen and carbon dioxide under a sterile environment. The volume ratio of nitrogen to carbon dioxide was 4:1, and the oxygen permeability of the fresh-keeping bag was less than 1cm 3 / (m 2 ·24h·0.1MPa);

[0070] After sealing the preservation bag containing Gongcai, place it in a storage environment with a temperature of 10°C and a relative humidity of 40%;

[0071] In the preservation step, the material of the fresh-keeping bag is a composite material of polyethylene and polyamide, and the thickness is 0.12 mm.

[0072] In this embodiment, the high quality of the Gongcai raw material is ensured by carefully selecting fresh, pest-free and tender Gongcai as raw materials, and removing the roots and yellow leaves. During the pretreatment process, the impurities and microorganisms on the surface of Gongcai can be effectively removed by rinsing with clean water and soaking in a salt solution of a specific concentration for disinfection, which reduces the impact on the quality of Gongcai during the subsequent processing, so that the processed Gongcai can retain its original taste, color and nutrients to the greatest extent. The killing step uses hot water treatment within a specific temperature range and time, as well as a suitable hot water to Gongcai mass ratio, which can quickly passivate the enzyme activity in Gongcai and prevent Gongcai from causing color changes, nutrient loss and texture deterioration due to enzymatic reactions during subsequent processing and storage. Rapid cooling to room temperature after killing helps to fix the quality of Gongcai and further ensure its taste and appearance.

[0073] During the dehydration and drying step, the cooled Gongcai is evenly spread on a multi-layer breathable drying rack. The appropriate spacing between each layer of the drying rack and the food-grade stainless steel material ensure that the Gongcai is evenly heated and ventilated during the drying process, which is conducive to the smooth discharge of moisture. The specific pre-freezing temperature, time, drying vacuum degree and temperature, and drying time parameter settings in the vacuum freeze dryer can sublimate the moisture in the Gongcai under a low temperature and low pressure environment, avoiding the damage to the nutritional components and quality of the Gongcai by high temperature, so that the Gongcai maintains a good shape and quality after dehydration and drying, and the moisture content can be accurately controlled within the appropriate range of 5%-8%.

[0074] In the preservation step, the dehydrated Gongcai is placed in a fresh-keeping bag filled with a specific ratio of mixed gases. This gas combination can inhibit the respiration of Gongcai and the growth and reproduction of microorganisms. Nitrogen, as an inert gas, can reduce the oxidation of oxygen on Gongcai, and carbon dioxide can further inhibit the respiratory metabolism of Gongcai. The synergistic effect of the two creates a good fresh-keeping gas environment for Gongcai, effectively extending the shelf life of Gongcai.

[0075] The low oxygen permeability of the fresh-keeping bag can prevent external oxygen from entering the bag, maintain a stable gas environment in the bag, and further ensure the preservation effect of Gongcai.

[0076] After sealing the fresh-keeping bag containing Gongcai, place it in a storage environment with a temperature of 10℃ and a relative humidity of 40%. This low-temperature and low-humidity environment can slow down the physiological activities and chemical reactions of Gongcai and reduce the growth rate of microorganisms. It cooperates with the gas environment in the fresh-keeping bag to comprehensively ensure the quality stability of Gongcai during the storage process, reduce the risk of deterioration, and enable Gongcai to maintain good edible value and commodity value for a longer period of time.

[0077] In summary, in the entire processing method, each step from pretreatment, withering, dehydration and drying to preservation has clear process parameters, such as the length range of Gongcai, concentration of salt solution, soaking time, citric acid concentration in hot water for withering, drying rack parameters, vacuum freeze-drying parameters, preservation bag materials, etc. These detailed parameters provide clear operational guidance for actual production and processing, which is easy for workers to understand and implement, and is conducive to ensuring the stability and consistency of product quality.

[0078] Food-grade stainless steel is used as the material of the multi-layer breathable drying rack to ensure the hygiene and safety of Gongcai during the processing; the fresh-keeping bags are made of a composite material of polyethylene and polyamide, which has both good gas barrier properties and appropriate strength. The selection of these materials meets the requirements of food processing and also helps to improve processing efficiency and product quality.

[0079] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A freeze-drying, dehydrating and preserving method for Gongcai, characterized in that: The following steps are involved: Step 1: Preprocessing Select fresh, pest-free, tender Gongcai, remove the roots and yellow leaves of Gongcai, keep the stems intact, and finally peel and cut into strips; Rinse the selected Gongcai with clean water for 2-3 times, then soak it in a 0.5%-1% salt solution for 10-15 minutes for disinfection, then rinse it with clean water and drain the surface water; Step 2: Finishing Put the pre-treated Gongcai into hot water at a temperature of 90-95°C for 2-3 minutes, and the mass ratio of hot water to Gongcai is 5:1-6:1; After killing the green, quickly remove the Gongcai and put it into cold water to cool to room temperature. The cold water temperature is 5-10℃. Step 3: Dehydration and drying Spread the cooled Gongcai evenly on a multi-layer air-permeable drying rack, with the spacing between each layer of the drying rack being 10-15 cm; The drying rack on which the Gongcai is placed is placed in a vacuum freeze dryer, first pre-frozen at -30°C to -25°C for 2-3 hours, and then dried at a vacuum degree of 10-20 Pa and a temperature of -20°C to -15°C for 8-10 hours until the water content of the Gongcai is reduced to 5%-8%; Step 4: Keep fresh Take the dehydrated Gongcai out of the dryer and quickly put it into a fresh-keeping bag filled with a mixture of nitrogen and carbon dioxide under a sterile environment. The volume ratio of nitrogen to carbon dioxide is 3:2-4:1, and the oxygen permeability of the fresh-keeping bag is less than 1cm 3 / (m 2 ·24h·0.1MPa); After sealing the fresh-keeping bag containing Gongcai, place it in a storage environment with a temperature of 5-10°C and a relative humidity of 30%-40%.

2. The freeze-drying, dehydration and preservation method of Gongcai according to claim 1, characterized in that: In the pretreatment step, the length of the Gongcai is 20-30 cm.

3. The freeze-drying, dehydration and preservation method of Gongcai according to claim 1, characterized in that: In the fixing step, citric acid with a mass concentration of 0.1%-0.2% is added to the hot water.

4. The freeze-drying, dehydration and preservation method of Gongcai according to claim 1, characterized in that: In the dehydration and drying step, the multi-layer breathable drying rack is made of food-grade stainless steel, and the diameter of the air holes is 0.5-1 mm.

5. The freeze-drying, dehydration and preservation method of Gongcai according to claim 1, characterized in that: In the preservation step, the material of the fresh-keeping bag is a composite material of polyethylene and polyamide, and the thickness is 0.08-0.12 mm.

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