CN108294219A - A kind of food freeze dryer and its lyophilized technique - Google Patents

Abstract

The invention discloses a kind of food freeze dryer and its lyophilized techniques, its key points of the technical solution are that including on the charging tray that food to be lyophilized is put into casing, start refrigerating plant to cool down to casing internal, start vacuum pump after food product refrigeration to vacuumize casing internal, close refrigerating plant and vacuum pump, start heating device to heat food, close heating device, shut-off valve is opened by being passed through pure water vapour in steam transmitting pipe road direction casing, it is then shut off shut-off valve, food is stood, take out the food after the completion of freeze-drying, it is quick food has been reached, the effect equably to get damp again.

Description

A kind of food freeze-drying machine and its freeze-drying process

technical field

The invention relates to the field of food freeze-drying, in particular to a food freeze-drying machine and a freeze-drying process thereof.

Background technique

With the development of the times, people's living standards are constantly improving, and people's requirements for food are also more stringent. Drying is one of the methods to keep materials from spoilage, and freeze-drying is a more common drying method now. The water content in the food is reduced to about 2%, while trying not to destroy the nutrients in the food.

Existing reference can be made to the Chinese patent whose authorization notification number is CN206525483U, which discloses a detachable food freeze-drying machine, comprising walking wheels, a casing, a freeze-drying rack and an exhaust pipe, and the bottom of the casing is equipped with Walking wheels, a motor is installed at the bottom end inside the casing, and a shaft is fixedly installed on the output end of the motor through a coupling, and a freeze-drying frame is fixed on the outer wall of the shaft, and the casings on both sides of the motor Two refrigerating devices are installed on the top, and the output end of the refrigerating device is located on the upper surface of the partition, a door is provided on the casing on the side of the food storage tank, and a door is provided on the side of the casing far away from the door. A heating ring, and a heating plate is inlaid on the inner side of the heating ring. Compared with the traditional drying method, the present invention adopts freeze-drying, so that the volume of the food remains unchanged during the drying process, and ensures that the food can be dried thoroughly. The set motor and heating ring can make the food evenly heated, and the set sieving The plate can screen the dried food, which is convenient for the separation of food.

Existing food freeze dryers freeze-dry the food so that the water content in the food is too small, which will affect the taste of the food and other factors. Usually, the food is brought into the box and water vapor is added to rehydrate, but this method of rehydration not only rehydrates Uneven and slow to regain moisture.

Contents of the invention

The purpose of the present invention is to provide a food freeze-drying machine, which can carry out vacuum rehydration on the food while freeze-drying the food, so that the food rehydration speed is fast and the moisture resurgence is uniform.

Above-mentioned technical purpose of the present invention is achieved through the following technical solutions:

A food freeze dryer, comprising a casing, a plurality of trays slidably connected in the casing, a heating device fixedly connected in the casing, and a refrigeration device fixedly connected in the casing, in which a The vacuum pump is also fixedly connected with a steam pipeline that feeds pure water vapor into the inside of the casing, and a shut-off valve that controls the on-off of the steam pipeline is fixedly connected on the steam pipeline. A flow meter for detecting the water vapor flow inside the steam pipeline is fixedly connected.

By adopting the above scheme, the food can be rehydrated under the vacuum condition in the casing, and the staff can control the flow of water vapor through the flow meter and the stop valve, so as to control the moisture resurgence process of the food.

Preferably, a humidity sensor for detecting humidity in the casing is fixed inside the casing.

By adopting the above solution, the humidity sensor can transmit the water vapor content in the casing to the staff in real time, which is convenient for the staff to monitor the amount of water vapor absorbed by the food and adjust the amount of water vapor introduced.

Preferably, the heating device includes a plurality of heating plates fixedly connected in the casing and located below the tray, and a heating pipeline fixedly connected to the heating plates for supplying heat to the heating plates.

By adopting the above scheme, the food in the tray is heated through the heating plate under the tray, which can make full use of the heat of the heating plate, and the heating pipeline is convenient for the staff to control the temperature of the heating plate from outside the casing.

The object of the present invention is to provide a food freeze-drying process, in which moisture regain is carried out in a vacuum environment in the casing, so that the food regains moisture evenly and quickly.

Above-mentioned technical purpose of the present invention is achieved through the following technical solutions:

A food freeze-drying process, comprising the following steps:

(a) Put the food to be freeze-dried on the material tray in the casing, and start the refrigeration device to cool down the inside of the casing;

(b) After the food is frozen, start the vacuum pump to evacuate the inside of the casing;

(c) Turn off the refrigeration device and vacuum pump, and start the heating device to heat the food;

(d) Turn off the heating device, open the shut-off valve to allow the steam pipeline to introduce pure water vapor into the casing, then close the shut-off valve, and let the food stand still;

(e) Take out the freeze-dried food.

By adopting the above scheme, after the food is freeze-dried, the food is not taken out, and the space in the casing is kept vacuum, and then water vapor is introduced into the casing to regain moisture, so that the food can regain moisture under vacuum conditions. It is in contact with the outside world, so the food will not be contaminated when it absorbs water, and the food will absorb water more evenly under the pressure of vacuum, and the moisture regain speed will also be accelerated. Control the moisture in the food to reach the required amount.

Preferably, the refrigeration device (14) reduces the temperature inside the casing (1) to below 0 degrees Celsius.

By adopting the above scheme, the temperature of the food drops below 0 degrees Celsius, which will freeze most of the water in the food, making it ready for subsequent heating and sublimation.

Preferably, the internal pressure of the casing is 80Pa after vacuuming.

By adopting the above scheme, the vacuum pump can pump the pressure inside the casing to about 80Pa to complete the whole process. The pressure of 80Pa just satisfies the vacuum regain condition of food under the premise of satisfying the freeze-drying condition. Under this pressure, the moisture regain of food is fast , regain moisture evenly.

better, c , The heating temperature is 80 to 90 degrees Celsius for 12 hours;

c , The heating temperature is reduced to 70 degrees Celsius for 5 to 6 hours;

c , The heating temperature is reduced to 55 to 60 degrees Celsius for 6 to 7 hours.

By adopting the above scheme, when freeze-drying shallots and diced meat, the food is heated in three stages. First, the temperature is raised to 80 to 90 degrees Celsius, so that the food can be sublimated quickly under high temperature conditions, and a large amount of water is lost. The temperature is lowered to 70 degrees Celsius, so that the food can be dried smoothly at a lower temperature, and the nutrition of the food is prevented from being damaged due to the high temperature for too long. Finally, the temperature is lowered to 55 to 60 degrees Celsius to fully sublimate the moisture in the food. The water content of the food is reduced to about 2%, the whole process is relatively stable, and the impact on the nutritional content of the food is relatively small.

better, d , Repeat step (d) one to two times.

By adopting the above scheme, the food can fully absorb water vapor by injecting water vapor into the casing in stages, which not only facilitates the control of the water content of the food, but also allows the food to absorb water vapor gently instead of absorbing a large amount of water at one time. Water vapor, so that the moisture absorbed by the food is more uniform.

Preferably, said step d is further divided into:

d _1. Turn off the heating device (13), open the shut-off valve (162) to allow the steam pipeline (16) to introduce pure water vapor into the casing (1), and the humidity sensor (17) detects the humidity in the casing (1). Humidity and record;

d _2. Close the stop valve (162), let the food stand still, and the humidity sensor (17) detects the humidity in the casing (1) again and records it;

d _3. Subtract the data measured twice by the humidity sensor (17) to obtain the amount of water vapor absorbed by the food;

d _4. Calculate the amount of water vapor that needs to be absorbed by the food to meet the standard water content according to the quality of the food, the water content that the food needs to achieve, and the water content after the freeze-drying of the food is 2%;

d _5. Calculate the amount of water vapor that the food needs to absorb by subtracting the amount of water vapor that has been absorbed by the food from the amount of water vapor that is calculated above;

d _6. Open the stop valve (162) again according to the amount of water vapor that the food still needs to absorb;

d _7. Close the shut-off valve (162) after releasing enough water vapor, and let the food stand still.

By adopting the above scheme, through the cooperation of the humidity sensor and the flow meter, the staff can fine-tune the amount of water vapor introduced according to the data of the humidity sensor and the flow meter, and can accurately adjust the amount of water vapor when rehydrating a certain food for the first time. Calculate the data such as the amount of water vapor and absorption time that this food needs when it regains moisture, so as to facilitate automatic processing in the future.

In summary, the present invention has the following beneficial effects:

1. After the food is freeze-dried, the food is not taken out, and the space inside the casing is kept vacuum, and then water vapor is introduced into the casing to regain moisture, so that the food can regain moisture under vacuum conditions, because the food does not contact with the outside world , so the food will not be contaminated when it absorbs water, and the food will absorb water more uniformly under the vacuum pressure, and the moisture regain speed will also be accelerated. By controlling the amount of water vapor introduced into the casing, the inside of the food can also be better controlled. moisture, to achieve the required amount;

2. The food can be rehydrated under the vacuum condition in the casing, and the staff can control the flow of water vapor through the flow meter and the stop valve, so as to control the moisture resurgence process of the food;

3. Through the cooperation of the humidity sensor and the flow meter, the staff can fine-tune the amount of water vapor introduced according to the data of the humidity sensor and the flow meter, and can accurately calculate the amount of water vapor when rehydrating a certain food for the first time. When a food regains moisture, it needs data such as the amount of water vapor and the time of absorption, so as to facilitate automatic processing in the future.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the lyophilizer in embodiment one;

Fig. 2 is a schematic diagram highlighting the internal structure of the lyophilizer in Example 1;

Fig. 3 is a schematic structural view of the prominent steam pipeline and refrigeration device in Embodiment 1;

Fig. 4 is the flowchart of freeze-drying overall process in embodiment two;

Fig. 5 is a flow chart of the process of moisture rejuvenation of dried meat in the second embodiment.

In the figure, 1. casing; 11. hatch; 12. material tray; 121. material rack; 13. heating device; 131. heating plate; 132. heating pipeline; 14. refrigeration device; 15. vacuum pump; 151 16. Steam pipeline; 161. Flow meter; 162. Stop valve; 163. Steam outlet; 17. Humidity sensor; 18. Air pressure detection device.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings. Wherein the same components are denoted by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the drawings, and the words "bottom" and "top "Face", "inner" and "outer" refer to directions toward or away from, respectively, the geometric center of a particular component.

Embodiment 1: A food freeze dryer, as shown in FIG. 1 and FIG. 2 , includes a casing 1 , a hatch 11 rotatably connected to the casing 1 , and a rack 121 fixedly connected in the casing 1 .

A plurality of trays 12 are placed on the shelf 121 , and a heating device 13 is connected to the casing 1 at the positions corresponding to the trays 12 . The heating device 13 includes a plurality of interconnected heating plates 131 fixedly connected to the material rack 121 and located at the bottom of the material tray 12 and two heating pipelines 132 connected to the heating plates 131 on both sides. The heating pipelines 132 extend Out of the casing 1, it is convenient for the staff to control the temperature inside the casing 1 outside the casing 1.

A refrigerating device 14 is fixedly connected in the casing 1, and the refrigerating device 14 can reduce the temperature in the casing 1 to below 0 degrees Celsius.

A vacuum tube 151 is fixedly connected to the casing 1 , and the vacuum tube 151 protrudes from the casing 1 and is fixedly connected to a vacuum pump 15 at one end of the vacuum tube 151 protruding from the casing 1 . The vacuum pump 15 vacuumizes the inside of the casing 1 through the vacuum tube 151 .

As shown in FIGS. 2 and 3 , a steam pipeline 16 is fixedly connected in the casing 1 , and several steam outlets 163 are opened on the steam pipeline 16 , and the steam pipeline 16 extends out of the casing 1 . The water vapor enters the inside of the casing 1 from the steam outlet 163 through the steam delivery pipeline 16 to rehydrate the food in the casing 1 .

A cut-off valve 162 and a flow meter 161 are fixedly connected to the part of the steam pipeline 16 protruding from the casing 1. The flowmeter 161 can measure the amount of water vapor delivered by the steam pipeline 16 to the casing 1, and the shut-off valve 162 is used to control On-off of the steam pipeline 16.

A humidity sensor 17 is fixed inside the casing 1 , and the humidity sensor 17 can detect the humidity inside the casing 1 , which is convenient for staff to monitor the humidity inside the casing 1 .

An air pressure detection device 18 is fixed in the casing 1, and the air pressure detection device 18 is used to detect the air pressure in the casing 1, so that the staff can control the switch of the vacuum pump 15 according to the value of the air pressure detection device 18.

Embodiment 2: a kind of food freeze-drying process, as shown in Figure 4, the staff first opens the hatch 11, puts the food to be freeze-dried on the tray 12 in the casing 1, then closes the hatch 11, and simultaneously Start the refrigeration device 14 to cool down the inside of the casing 1 . Start the vacuum pump 15 after the temperature in the casing 1 drops below 0 degrees Celsius, and the vacuum pump 15 vacuumizes the casing 1 through the vacuum tube 151. When the air pressure detection device 18 detects that the air pressure in the casing 1 drops to about 80Pa , turn off the vacuum pump 15 and the refrigeration unit 14.

Start the heating device 13, and the specific operation is to pass hot water or hot air into the heating plate 131 through the heating pipeline 132 to sublimate the moisture in the food, then turn off the heating device 13 to complete the freeze-drying of the food, and finally make the food The water content in it is reduced to about 2%.

When the food needs to regain moisture, keep the internal vacuum of the casing 1, open the shut-off valve 162 to allow the steam pipeline 16 to enter the casing 1 with pure water vapor through the steam outlet 163 to rehydrate the food. Close the stop valve 162 after feeding a certain amount of water vapor, and leave the food for a period of time to allow the food to fully absorb the water vapor.

Finally, the hatch 11 is opened to take out the food after freeze-drying. The food regains moisture under vacuum conditions. Because the food does not contact with the outside world, the food will not be contaminated when it absorbs water, and the food will absorb water more uniformly under the vacuum pressure, and the moisture regain speed will also be accelerated. 1, the amount of water vapor introduced can also better control the moisture in the food to reach the required amount.

As shown in Figure 4 and Figure 5, when freeze-drying the diced meat, after the temperature of the diced meat is reduced to below 0 degrees Celsius by the refrigeration device 14, the vacuum pump 15 will reduce the pressure in the casing 1 to 80Pa, and then close the refrigeration device 14 , first heating the heating plate 131 to 80 degrees Celsius for 12 hours to allow the diced meat to sublimate quickly and remove a large amount of moisture inside the diced meat. Then reduce the temperature of the heating plate 131 to 70 degrees Celsius for 5 hours, and finally reduce the temperature of the heating plate 131 to 55 degrees Celsius for 7 hours. Allow the diced meat to fully sublimate and dry, and finally reduce the water content inside the diced meat to about 2%.

On the premise of maintaining the vacuum inside the casing 1 , the heat supply pipeline 132 no longer supplies heat to the heating plate 131 .

Open stop valve 162, according to flowmeter 161, slowly pass into about 70kg water vapor in casing 1 with 30 minutes according to flowmeter 161, then close stop valve 162, allow diced meat to stand still in casing 1 for 15 minutes, make diced meat fully Absorbs water vapor. Then repeat above-mentioned process 2 times, open cabin door 11 after passing into about 70kg water vapor in casing 1 at last, diced meat is taken out, and the water content of diced meat is about 15% at this moment, completes the freeze-drying moisture regain of diced meat.

When freeze-drying the shallots, after the temperature of the shallots is reduced to below 0 degrees Celsius by the refrigeration unit 14, the pressure in the casing 1 is reduced to 80 Pa by the vacuum pump 15, then the refrigeration unit 14 is closed, and the heating plate 131 is heated to 90°C earlier. Celsius for 12 hours, allowing the shallots to sublimate quickly and remove a lot of water inside the shallots. Then reduce the temperature of the heating plate 131 to 70 degrees Celsius for 6 hours, and finally reduce the temperature of the heating plate 131 to 60 degrees Celsius for 6 hours. Let the shallots be fully sublimated and dried, and finally reduce the water content inside the shallots to about 2%.

This food freeze-drying process can also be applied to other foods. When a food is first freeze-dried and rehydrated, the following steps can be used to obtain the data required for the freeze-dried and rehydrated food:

First, after the freeze-drying is completed, the heating device 13 is turned off, the shut-off valve 162 is opened to allow the steam pipeline 16 to feed pure water vapor into the casing 1, and the humidity sensor 17 detects the humidity in the casing 1 and records it manually.

Then close the stop valve 162, leave the food still, and the humidity sensor 17 detects the humidity in the casing 1 again and records it manually.

Subtract the data measured twice by the humidity sensor 17 to obtain the amount of water vapor absorbed by the food. Multiply the weight of the food by the moisture content per kilogram of the food to obtain the total internal moisture content of the food after the moisture resurgence is completed, and then use the total moisture content minus the original moisture content of the food multiplied by 2% to obtain the food moisture content The amount of water vapor that needs to be absorbed to meet the standard.

The amount of water vapor that the food still needs to absorb is obtained by subtracting the amount of water vapor that has been absorbed by the food from the amount of water vapor that is calculated above.

Open the stop valve 162 again according to the amount of water vapor that the food still needs to absorb. Close the shut-off valve 162 after emitting enough steam, and the food is left to stand for 15 minutes.

This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications to this embodiment without creative contribution as required after reading this specification, but as long as they are within the rights of the present invention All claims are protected by patent law.

Claims (9)

1. A food freeze-drying machine, comprising a casing (1), a plurality of charging trays (12) that are slidably connected in the casing (1), a heating device (13) that is fixedly connected in the casing (1) and The refrigerating device (14) fixedly connected in the casing (1) is characterized in that: a vacuum pump (15) is fixedly connected in the casing (1), and a directional casing ( 1) The steam pipeline (16) that feeds pure water vapor inside is fixedly connected with a shut-off valve (162) that controls the on-off of the steam pipeline (16). The pipeline (16) is fixedly connected with a flow meter (161) for detecting the water vapor flow inside the steam transmission pipeline (16). 2. The food freeze dryer according to claim 1, characterized in that: a humidity sensor (17) for detecting the humidity inside the casing (1) is fixed inside the casing (1). 3. The food freeze-drying machine according to claim 1, characterized in that: the heating device (13) comprises a plurality of heating plates (131) fixedly connected in the casing (1) and positioned below the tray (12) and A heat supply pipeline (132) fixedly connected to the heating plate (131) for supplying heat to the heating plate (131). 4. A food freeze-drying process, comprising the following steps: (a) Put the food to be freeze-dried on the material tray (12) in the casing (1), start the refrigeration device (14) to cool down the inside of the casing (1); (b) Start the vacuum pump (15) to evacuate the inside of the casing (1) after the food is frozen; (c) Turn off the refrigeration unit (14) and the vacuum pump (15), start the heating unit (13) to heat the food; (d) Turn off the heating device (13), open the shut-off valve (162) to allow the steam pipeline (16) to feed pure water vapor into the casing (1), then close the shut-off valve (162), and leave the food to stand ; (e) Take out the freeze-dried food. 5. a kind of food freeze-drying process according to claim 4, is characterized in that, described step (a) is further divided into: The cooling device (14) reduces the temperature in the casing (1) to below 0 degrees Celsius. 6. a kind of food freeze-drying process according to claim 4, is characterized in that, described step (b) is further divided into: After vacuuming, the internal pressure of the casing (1) is 80Pa. 7. a kind of food freeze-drying process according to claim 4, is characterized in that, described step (c) is further divided into: c , The heating temperature is 80 to 90 degrees Celsius for 12 hours; c , The heating temperature is reduced to 70 degrees Celsius for 5 to 6 hours; c , The heating temperature is reduced to 55 to 60 degrees Celsius for 6 to 7 hours. 8. a kind of food freeze-drying process according to claim 4, is characterized in that, also has after described step (d): d , Repeat step (d) one to two times. 9. a kind of food freeze-drying process according to claim 7, is characterized in that, described step (d) is further divided into: d _1. Turn off the heating device (13), open the shut-off valve (162) to allow the steam pipeline (16) to introduce pure water vapor into the casing (1), and the humidity sensor (17) detects the humidity in the casing (1). Humidity and record; d _2. Close the stop valve (162), let the food stand still, and the humidity sensor (17) detects the humidity in the casing (1) again and records it; d _3. Subtract the data measured twice by the humidity sensor (17) to obtain the amount of water vapor absorbed by the food; d _4. Calculate the amount of water vapor that needs to be absorbed by the food to meet the standard water content according to the quality of the food, the water content that the food needs to achieve, and the water content after the freeze-drying of the food is 2%; d _5. Calculate the amount of water vapor that the food needs to absorb by subtracting the amount of water vapor that has been absorbed by the food from the amount of water vapor that is calculated above; d _6. Open the stop valve (162) again according to the amount of water vapor that the food still needs to absorb; d _7. Close the shut-off valve (162) after releasing enough water vapor, and let the food stand still.