A drying method of pre-ripened tremella pulp

Abstract

This invention discloses a drying method for pre-cooked tremella fuciformis paste. The method includes the following steps: 1) crushing and pulping pre-cooked tremella fuciformis to obtain pre-cooked tremella fuciformis paste; 2) transferring the pre-cooked tremella fuciformis paste to a pressure mixing vessel, opening the exhaust valve, introducing CO2 gas, venting the air, closing the exhaust valve, controlling the CO2 pressure in the mixing vessel to 0.1-0.8 MPa, controlling the temperature to 45-65℃, stirring for 5-15 minutes to dissolve the CO2, then opening the discharge valve, allowing the CO2-dissolved tremella fuciformis paste to be transported along the pipeline under pressure and slowly depressurized to form a paste-like material, which is then coated onto a grid drying tray; 3) placing the drying tray on a drying rack equipped with an infrared heater and pushing it into an oven for drying. This invention uses carbon dioxide foaming to transform the original gel-like tremella fuciformis paste into a paste with a carbon dioxide microbubble structure, and then utilizes the strong absorption of infrared radiation by carbon dioxide to assist in heating and drying the material with infrared radiation, thereby significantly improving drying efficiency and forming a porous and loose product structure.

Description

Technical Field

[0001] This invention relates to the field of food technology, specifically to a method for drying pre-cooked tremella fuciformis paste. Background Technology

[0002] Pre-cooked instant white fungus, also known as quick-soaking dried white fungus slices, is a new type of dried white fungus product. Due to its rich gelatinous content, soft and chewy texture, high rehydration rate, and short cooking time, it is highly favored by consumers. This product is an edible fungus dried product made from fresh white fungus through pre-cooking, pulping, and drying.

[0003] The raw material for pre-cooked instant white fungus is fresh white fungus fruiting bodies that have been pre-cooked by steaming or blanching and then mechanically crushed into a pulp. It has a gel-like, semi-liquid appearance with poor flowability and a moisture content of approximately 90%. The material has poor internal heat exchange capacity, and during the drying process, a crust forms on the surface, increasing resistance to internal moisture diffusion. Therefore, problems such as difficulty in dehydrating the internal material, long drying times, excessive surface dehydration, and material structure collapse often occur. This leads to product quality issues, mainly manifested as unstable rehydration properties, slow gelation, and a high proportion of hard cores after rehydration. Therefore, the drying process has become a crucial technical link affecting the production efficiency and product quality of pre-cooked instant white fungus.

[0004] Pre-cooked instant white fungus can quickly rehydrate and gelatinize after being steeped in boiling water, forming a white fungus soup. This is mainly due to the fact that during the pre-cooking process, the polysaccharides in the white fungus react with water to form a polysaccharide gel, which, during mechanical crushing, is suspended from the fungal fragments. These solids play a crucial supporting role in the material structure during drying, resulting in a porous and loose structure after drying. This structure is key to the product's rapid rehydration and gelatinization. However, because the polysaccharide content and fungal cell hardness of each batch of raw materials vary, the gel strength and solid support strength of the material after pre-cooking will differ. When the gel strength and solid support are insufficient, the material will collapse during drying, preventing rapid dehydration and shaping, ultimately leading to a significant deterioration in the product's rehydration and gelatinization performance. Summary of the Invention

[0005] The purpose of this invention is to provide a drying method for preparing pre-cooked, ready-to-eat tremella fuciformis paste. It aims to solve the following technical problems: 1. Improve the material support strength of the pre-cooked tremella fuciformis paste to prevent material collapse during drying; 2. Improve heat transfer within the material during drying, increase the internal temperature, and reduce moisture diffusion resistance, thereby improving drying efficiency; 3. Form a porous, multi-microporous structure in the material to improve the product's rehydration and gelling properties.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for drying pre-cooked tremella fuciformis paste includes the following steps:

[0008] 1) Preparation of pre-cooked tremella paste

[0009] The pre-cooked white fungus is crushed and pulped, and the moisture content of the pulp is adjusted to 85-95% to obtain pre-cooked white fungus pulp.

[0010] 2) Carbon dioxide foaming

[0011] Transfer the pre-cooked tremella syrup to a pressure mixing vessel, seal the vessel, open the exhaust valve, introduce CO2 gas, and after the air is expelled, close the exhaust valve. Control the CO2 pressure inside the mixing vessel to 0.1-0.8 MPa and the temperature to 45-65℃. Stir for 5-15 minutes under these conditions to dissolve the CO2. Then open the discharge valve to allow the CO2-dissolved tremella syrup to be transported along the pipeline under pressure and slowly depressurized to form a paste. Apply the paste to a grid drying tray with a thickness of 10-20 mm.

[0012] 3) Infrared combined drying

[0013] Place the material-carrying drying tray on the drying rack equipped with an infrared heater, and push it into the drying oven for drying. The radiating surface of the infrared heater should cover the material surface of the tray. Adjust the surface temperature of the infrared heater to 300-380℃, and the distance between the infrared heating element and the material surface should be 80-120mm. By adjusting the oven air speed and inlet air temperature, maintain the material surface temperature at 70-85℃ and the internal temperature at 45℃-55℃ during the drying process. Stop drying when the material moisture content is below 10%, collect and package the material to obtain the finished product.

[0014] Furthermore, the pre-cooked white fungus in step 1) refers to the white fungus being cooked using one or more methods such as blanching, steaming, or microwave treatment.

[0015] Furthermore, the pressure mixing vessel in step 2) can be an intermittently operating pressure mixing vessel or a continuously operating pressure mixing vessel with a feed pump.

[0016] Furthermore, the oven in step 3) is an electric heating oven, a steam coil oven, a heat pump oven, etc.

[0017] Furthermore, the infrared heater in step 3) can be a graphene microcrystalline infrared heater, a quartz infrared heater, a carbon fiber infrared heater, a metal infrared heater, a ceramic infrared heater, etc.

[0018] The principle and advantages of the technical solution of this invention are as follows:

[0019] Carbon dioxide has a certain solubility in water, and its solubility increases with pressure. At 30℃ and 0.2 MPa, 1 kg of water can dissolve approximately 1.2 m³ of carbon dioxide. 3 Carbon dioxide gas is released. When the ambient pressure decreases or the solution temperature increases, some of the dissolved carbon dioxide escapes from the solution as gas, forming a large number of carbon dioxide bubbles. The tremella fuciformis slurry is placed in a pressure stirring vessel, and carbon dioxide is introduced. By increasing the carbon dioxide pressure and stirring, the carbon dioxide dissolves in the slurry. Then, the dissolved carbon dioxide escapes through a slow depressurization process, forming a large number of tiny carbon dioxide bubbles in the colloid. Because the pre-cooked tremella fuciformis slurry is a viscous colloid, it effectively retains the carbon dioxide bubbles, causing the colloid to expand and form a paste. Simultaneously, due to the increased material temperature during drying, the pressure within the carbon dioxide bubbles provides excellent support for the entire paste, improving the material's structural stability and effectively preventing collapse during drying. Furthermore, after the pre-cooked tremella fuciformis slurry foams into a paste, the water-air interface area increases, and the resistance to moisture diffusion decreases, facilitating the migration of internal moisture during drying and increasing the drying speed of the material. It also forms a porous and loose structure within the finished product, significantly improving its rehydration properties and gelation rate.

[0020] Carbon dioxide, as a greenhouse gas, has a strong ability to absorb infrared radiation and can convert the absorbed infrared energy into heat energy. Therefore, by supplementing the drying process of foamed tremella syrup with infrared radiation heating, the absorption effect of carbon dioxide microbubbles in the colloid on infrared radiation can be utilized to significantly increase the internal temperature of the material and accelerate the drying speed of the moisture in the material. This solves the problem that the internal temperature of tremella syrup was low during the drying process due to poor internal heat exchange capacity, and further improves the drying rate of the material.

[0021] The maximum absorption wavelength of carbon dioxide in the infrared band is 4.26 μm. Infrared spectroscopy plays a crucial guiding role in the selection of infrared heating methods. Only by selecting an infrared source that matches the absorption peak of the heated material can radiation efficiency be maximized and heating performance improved. Currently, different types of infrared heaters have different peak infrared wavelengths. Furthermore, the peak wavelength of the same infrared heater will change depending on its operating temperature. Generally speaking, lowering the operating temperature of the infrared emitter can shift its peak wavelength into the longer wavelength region. Taking a graphene microcrystalline infrared heater as an example, when the operating temperature is around 320℃, its peak radiation region is precisely between 4-5 μm, making it suitable for auxiliary heating of carbon dioxide-foamed tremella fuciformis pulp.

[0022] This invention employs a combined carbon dioxide foaming and infrared drying technology to provide a rapid and high-quality drying method for pre-cured tremella fuciformis paste. Compared with existing technologies, the advantages of this invention are:

[0023] This invention utilizes carbon dioxide foaming to transform the original gel-like tremella syrup into a paste with a carbon dioxide microbubble structure. Then, leveraging the strong absorption of infrared radiation by carbon dioxide, infrared light is used to assist in heating and drying the material, significantly improving drying efficiency and creating a porous, loose product structure. Compared to existing technologies, the drying time for tremella syrup using this invention can be reduced from 7-8 hours to 3-4 hours, effectively preventing material collapse during drying and improving the adaptability of the production process to different tremella raw materials. Regarding product performance, existing products require steeping in a thermos for over 10 minutes to fully gel and form a thick soup, while the pre-cooked, ready-to-eat tremella syrup produced by this invention has significantly improved rehydration performance; it only needs to be steeped in boiling water for 5 minutes to gel and form a thick soup, greatly enhancing the product's ease of use. Attached Figure Description

[0024] Figure 1 This is a comparison diagram showing the morphological differences of the tremella paste before and after the foaming treatment of this invention.

[0025] Figure 2 The images show a comparison of the appearance of the products in Example 1 and Comparative Example 1.

[0026] Figure 3 This is a comparison of the brewing effects of the products in Example 1 and Comparative Example 1.

[0027] Figure 4 The image is a scanning electron microscope (SEM) image (1.0KX) of the product in Comparative Example 1.

[0028] Figure 5 The image shown is a scanning electron microscope (SEM) image (1.0KX) of the product from Example 1. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments. It should be understood that these embodiments are only some implementations of the present invention and are not intended to limit the scope of protection of the present invention.

[0030] Example 1

[0031] A method for drying pre-cooked tremella fuciformis paste includes the following steps:

[0032] Step 1: Prepare pre-cooked tremella paste

[0033] Take 50 kg of cooked fresh white fungus, crush and pulp it using a rotary cutter, adjust the moisture content of the pulp to about 90%, stir evenly, and obtain pre-cooked white fungus pulp.

[0034] Step 2, Carbon dioxide foaming

[0035] The pre-cooked tremella slurry is fed into a pressure mixing vessel. The exhaust valve at the top of the mixing vessel is opened to introduce CO2 gas. After the air is discharged, the exhaust valve is closed. The CO2 pressure inside the mixing vessel is controlled at 0.5 MPa, the jacket temperature of the mixing vessel is 50℃, and the stirring speed is 30 r / min. Under these conditions, the mixture is stirred for 10 minutes to complete the CO2 dissolution. Then, the discharge valve at the bottom of the mixing vessel is opened to allow the CO2-dissolved tremella slurry to be transported along the pipeline under pressure and slowly depressurized to form a paste. The paste is then spread on a grid drying tray and smoothed out to a thickness of 20 mm.

[0036] Step 3: Infrared combined drying

[0037] Place the drying trays containing the material on drying racks equipped with infrared heaters and push them into the heat pump oven for drying. Each drying rack above each tray is equipped with a graphene infrared heating plate, the radiation surface of which completely covers the material surface of the tray. The heating plate is 100mm away from the material surface. The surface temperature of the infrared heating plate is adjusted to about 320℃ using a voltage regulator. By adjusting the air speed and inlet air temperature of the heat pump oven, the surface temperature of the material is maintained at no more than 85℃ and the internal temperature of the material is not lower than 45℃ during the drying process. Drying is stopped after about 3 hours when the moisture content of the material is lower than 10%. The collected material is weighed and packaged to obtain the finished product of quick-drying tremella slices.

[0038] Example 2

[0039] A method for drying pre-cooked tremella fuciformis paste includes the following steps:

[0040] Step 1: Prepare pre-cooked tremella paste

[0041] Take 50 kg of cooked fresh white fungus, crush and pulp it using a rotary cutter, adjust the moisture content of the pulp to about 90%, stir evenly, and obtain pre-cooked white fungus pulp.

[0042] Step 2, Carbon dioxide foaming

[0043] The pre-cooked tremella slurry is fed into a pressure mixing vessel. The exhaust valve at the top of the mixing vessel is opened to introduce CO2 gas. After the air is discharged, the exhaust valve is closed. The CO2 pressure inside the mixing vessel is controlled at 0.3 MPa, the jacket temperature of the mixing vessel is 45℃, and the stirring speed is 30 r / min. Under these conditions, the mixture is stirred for 15 minutes to complete the CO2 dissolution. Then, the discharge valve at the bottom of the mixing vessel is opened to allow the CO2-dissolved tremella slurry to be transported along the pipeline under pressure and slowly depressurized to form a paste. The paste is then spread on a grid drying tray and smoothed out to a thickness of 10 mm.

[0044] Step 3: Infrared combined drying

[0045] Place the drying trays containing the material on drying racks equipped with infrared heaters and push them into the heat pump oven for drying. Each drying rack above each tray is equipped with a graphene infrared heating plate, the radiation surface of which completely covers the material surface of the tray. The distance between the heating plate and the material surface is 80mm. The surface temperature of the infrared heating plate is adjusted to about 300℃ using a voltage regulator. By adjusting the air speed and inlet air temperature of the heat pump oven, the surface temperature of the material is maintained at 80℃ and the internal temperature of the material is not lower than 50℃ during the drying process. Drying is stopped after about 3 hours when the moisture content of the material is lower than 10%. The material is then collected, weighed, and packaged to obtain the finished product of quick-drying tremella slices.

[0046] Example 3

[0047] A method for drying pre-cooked tremella fuciformis paste includes the following steps:

[0048] Step 1: Prepare pre-cooked tremella paste

[0049] Take 50 kg of cooked fresh white fungus, crush and pulp it using a rotary cutter, adjust the moisture content of the pulp to about 90%, stir evenly, and obtain pre-cooked white fungus pulp.

[0050] Step 2, Carbon dioxide foaming

[0051] The pre-cooked tremella slurry is fed into a pressure mixing vessel. The exhaust valve at the top of the mixing vessel is opened to introduce CO2 gas. After the air is discharged, the exhaust valve is closed. The CO2 pressure inside the mixing vessel is controlled at 0.8 MPa, the jacket temperature of the mixing vessel is 65℃, and the stirring speed is 60 r / min. Under these conditions, the mixture is stirred for 5 minutes to complete the CO2 dissolution. Then, the discharge valve at the bottom of the mixing vessel is opened to allow the CO2-dissolved tremella slurry to be transported along the pipeline under pressure and slowly depressurized to form a paste. The paste is then spread on a grid drying tray and smoothed out to a thickness of 15 mm.

[0052] Step 3: Infrared combined drying

[0053] Place the drying trays containing the material on drying racks equipped with infrared heaters and push them into the heat pump oven for drying. Each drying rack above each tray is equipped with a graphene infrared heating plate, the radiation surface of which completely covers the material surface of the tray. The distance between the heating plate and the material surface is 120mm. The surface temperature of the infrared heating plate is adjusted to about 320℃ using a voltage regulator. By adjusting the air speed and inlet air temperature of the heat pump oven, the surface temperature of the material is maintained at about 75℃ and the internal temperature of the material is not lower than 50℃ during the drying process. Drying is stopped after about 3 hours when the moisture content of the material is lower than 10%. The material is then collected, weighed, and packaged to obtain the finished product of quick-drying tremella slices.

[0054] Comparative Example 1

[0055] The pre-cooked tremella paste was dried using a heat pump drying oven.

[0056] Step 1: Prepare pre-cooked tremella paste

[0057] Take 50 kg of cooked fresh white fungus, crush and pulp it using a rotary cutter, adjust the moisture content of the pulp to about 90%, stir evenly, and obtain pre-cooked white fungus pulp.

[0058] Step 2: Material Laying

[0059] The pre-cooked tremella paste was spread on a grid drying tray and smoothed out, with the thickness of the paste controlled at 15mm.

[0060] Step 3: Heat pump drying

[0061] Place the material-carrying drying tray on the drying rack and push it into the heat pump oven for drying. In the initial stage of the drying process, adjust the airflow speed and inlet air temperature of the heat pump oven to achieve a drying oven temperature of 75℃ in hot air direct exhaust mode. After 4 hours, adjust to 60℃ circulating dehumidification mode and continue drying for about 2 hours. Stop drying when the material moisture content is below 10%. Collect, weigh, and package the material to obtain the finished product of quick-drying and drying tremella slices.

[0062] The appearance, moisture content, brewing performance, and microstructure of the quick-drying tremella slices harvested in Example 1 and Comparative Example 1 were compared. The morphology of the tremella slurry material changed significantly after CO2 foaming treatment, becoming a paste-like substance rich in air bubbles, with a volume expansion of approximately 1.8 times. Figure 1 In Example 1, with the same amount of material, the drying time was reduced by approximately 50% compared to Comparative Example 1, from about 6 hours to about 3 hours. Comparison of product appearance (...) Figure 2 The product prepared in Example 1 has a more porous and fluffy structure with higher whiteness, while the product prepared in Comparative Example 1 has more glass-like structures and a yellowish color. Comparing the rehydration performance, the product prepared in Example 1 fully rehydrates and releases its gel after being steeped in boiling water for 10 minutes, achieving the desired effect, while the product in Comparative Example 1, under the same conditions, did not fully rehydrate and remained clump-like. Figure 3 Comparing the microstructures of the two ( Figure 4 , Figure 5 The surface of the product prepared in Example 1 is significantly different from that of Comparative Example 1, and it has a large number of microporous structures, which is beneficial to improving its rehydration performance.

Claims

1. A method for drying pre-cooked tremella fuciformis paste, characterized in that, Includes the following steps: 1) Preparation of pre-cooked tremella paste The white fungus is cooked by blanching, steaming or microwave treatment to obtain pre-cooked white fungus; the pre-cooked white fungus is crushed and pulped to obtain pre-cooked white fungus pulp with a water content of 85-95%; 2) Carbon dioxide foaming Transfer the pre-cooked tremella syrup to a pressure mixing vessel, seal the vessel, open the exhaust valve, introduce CO2 gas, and after the air is expelled, close the exhaust valve. Control the CO2 pressure inside the mixing vessel to 0.1–0.8 MPa and the temperature to 45–65°C. Under these conditions, stir for 5–15 minutes to dissolve the CO2. Then open the discharge valve to allow the CO2-dissolved tremella syrup to be transported along the pipeline under pressure and slowly depressurized to form a paste. Spread the paste onto a grid drying tray with a thickness of 10–20 mm. 3) Infrared combined drying Place the material drying tray on the drying rack equipped with an infrared heater, push it into the drying oven for drying, adjust the surface temperature of the infrared heater to 300-380℃, and keep the distance between the infrared heating element and the material surface 80-120mm. By adjusting the oven wind speed and inlet air temperature, maintain the material surface temperature at 70-85℃ and the material internal temperature at 45-55℃ during the drying process. Stop drying when the material moisture content is below 10%, and collect and package the material.

2. The drying method for pre-cooked tremella fuciformis paste according to claim 1, characterized in that, In step 3), the oven is an electric oven, a steam coil oven, or a heat pump oven.

3. The drying method for pre-cooked tremella fuciformis paste according to claim 1, characterized in that, In step 3), the infrared heater is a graphene microcrystalline infrared heater, a quartz infrared heater, a carbon fiber infrared heater, a metal infrared heater, or a ceramic infrared heater.

4. The drying method for pre-cooked tremella fuciformis paste according to claim 1, characterized in that, In step 3), the radiating surface of the infrared heater should cover the material surface of the tray.

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