CN110881487A

CN110881487A - Food vacuum baking equipment beneficial to improving crispness of food

Info

Publication number: CN110881487A
Application number: CN201811059446.6A
Authority: CN
Inventors: 李明守
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-10
Filing date: 2018-09-10
Publication date: 2020-03-17

Abstract

The invention belongs to the field of food equipment, and particularly discloses food vacuum baking equipment beneficial to improving the crispness of food. The baking chamber is internally provided with a gas distributing head and a gas trapping head which are suitable for the uniform distribution of carrier gas, and the cooling chamber is internally provided with a cold air spraying head and an exhaust gas trapping hopper which are suitable for the uniform distribution of carrier gas. The baking device is communicated with the cooling device in a sealing mode and is suitable for transferring food, and the food inlet of the baking device and the food outlet of the cooling device are respectively provided with a gate in a sealing mode. The vacuum device is operated to vacuumize the baking chamber, food is baked in a vacuum environment with carrier gas, and the circulating device is operated to drive the carrier gas in the cooling chamber to circularly flow to cool the food. The food is baked and cooled in a vacuum environment with carrier gas, the crispness of the food is improved, the oxidation and deterioration substances and the oxygen residual quantity of the oil in the food are less, and the shelf life of the food is obviously prolonged.

Description

Food vacuum baking equipment beneficial to improving crispness of food

Technical Field

The invention relates to food baking equipment, in particular to food vacuum baking equipment beneficial to improving the crispness of food, and belongs to the field of food equipment.

Background

Crisp baked food, such as walnut cake, biscuit, sesame seed cake, dried purple sweet potato, potato chip and other food, has various varieties and different flavors, is popular with people, and in order to keep good crisp and reduce the consumption of preservative, a large amount of grease and swelling agent are often added to reduce the hardening of the food, so that the crisp and uniform of the food are improved, and the mouth feel is improved. The current food baking equipment is used for baking food in an air environment, the food bears atmospheric pressure and is easy to harden, and the baked food has poor crispness; the baking temperature is higher than 190 ℃, trace metal ion gas is volatilized at high temperature in a baking chamber, grease in food directly acts with oxygen in the air, grease is oxidized at high temperature and is subjected to metal catalytic hydrogen peroxide reaction to generate grease oxidation metamorphic substances, the oxidation metamorphic substances promote the high-temperature oxidation of the grease, the oxidation speed of the grease is accelerated, more grease oxidation metamorphic substances harmful to health are generated, the oxygen capturing capacity of the food is improved, the food is easy to be oxidized, rancid and deteriorate in storage, and the quality guarantee period is short. Accordingly, there is a need to develop a vacuum roasting apparatus for food that advantageously improves the crispness of the food, to overcome the above-mentioned problems in the prior art.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides the food vacuum baking equipment which is beneficial to improving the crispness of the food, the crispness of the food is improved by baking the food in the vacuum environment with carrier gas, the carrier gas discharges the baking volatile matters in time, the oil oxidation deterioration matters and the oxygen residual quantity in the food are less, and the quality guarantee period of the food is favorably prolonged.

As an embodiment of the present invention, a food vacuum baking apparatus for advantageously improving crispness of a food is characterized by comprising:

the gas supply device is suitable for supplying carrier gas, and an output port suitable for outputting the carrier gas is arranged on the gas supply device;

a baking device adapted to bake food in a vacuum environment with a carrier gas; the baking device is internally provided with a baking chamber, and the baking chamber is internally provided with a baking supporting belt which is suitable for bearing food to be baked and is arranged along the horizontal direction, an air distributing head which is suitable for guiding the carrier gas to flow to the baking supporting belt in a shunting way, and an air capturing head which is suitable for sucking and discharging the carrier gas; the output port of the gas supply device, which is suitable for outputting the carrier gas, is hermetically communicated with the input port of the gas distribution head, which is suitable for inputting the carrier gas, through a 1 st valve, and the baking device is provided with a 1 st temperature sensor which is suitable for detecting the temperature of the baked food and a vacuum gauge which is suitable for detecting the vacuum degree of a baking chamber;

the cooling device is suitable for cooling food in a carrier gas environment, a cooling chamber is arranged in the cooling device, a cold supporting belt which is suitable for bearing the food to be cooled and is arranged along the horizontal direction, a cold air spraying head which is suitable for guiding the carrier gas to flow to the cold supporting belt in a shunting manner, and an exhaust trapping hopper which is suitable for exhausting the carrier gas are arranged in the cooling chamber; the cooling device is provided with a 2 nd temperature sensor which is suitable for detecting the temperature of the cooled food, and an oxygen sensor which is suitable for detecting whether the air in the cooling chamber is completely discharged or not; the output port of the air supply device is hermetically communicated with the input port of the cold air sprinkling head suitable for inputting carrier gas through a 2 nd valve;

the vacuum device is suitable for providing a vacuum environment and comprises a filter and a vacuum pump, wherein the filter is suitable for filtering oil mist and particulate matters and the vacuum pump is suitable for providing the vacuum environment, and the filter and the vacuum pump are communicated in sequence; an output port of the gas trapping head, which is suitable for discharging the carrier gas, is hermetically communicated with an input port of the filter through a 3 rd valve;

the circulating device is suitable for driving carrier gas in the cooling chamber to circularly flow so as to cool the food, and the circulating device comprises a heat exchanger and a circulating pump which are communicated; an output port of the exhaust trapping bucket, which is suitable for the exhaust of the carrier gas, is in sealed communication with an input port of the heat exchanger through a 4 th valve; an output port of the circulating pump, which is suitable for the carrier gas to flow out, is hermetically communicated with an input port of the cold air sprinkling head;

the food output port of the baking device is in sealed communication with the food input port of the cooling device, the 1 st gate is arranged at the food input port of the baking device in a sealed mode, the 3 rd gate is arranged at the food output port of the cooling device in a sealed mode, and the 2 nd gate is arranged between the food output port of the baking device and the food input port of the cooling device in a sealed mode, so that the baking device is suitable for baking food in a vacuum environment with load and cooling food in a carrier gas environment.

The food vacuum baking device of the above embodiment can bake the food in a vacuum environment with a carrier gas and cool the food in a carrier gas environment. Before the food is baked, a baking process corresponding to the food needs to be formulated, wherein the baking process comprises presetting set values of vacuum degree and evacuation reference value, and setting values of carrier gas parameter, baking vacuum degree, baking temperature and cooling temperature which are associated with time, so that the baking system is controlled to bake the food. Based on the baking process, the No. 1 gate of the baking device is operated to be opened, the baking device is operated to transfer the food to be baked into a baking chamber of the baking device, the No. 1 gate is operated to be closed, and the food to be baked is in a state of being isolated from the external air; based on the baking process, operating the 3 rd valve to open circulation, operating the vacuum pump to start, vacuumizing a flow path to circulate, sucking and exhausting air in the baking chamber, vacuumizing the baking chamber and obtaining a vacuum environment required by baking; when the measured value fed back by the vacuum gauge is smaller than the preset vacuum degree in the baking process, the air in the baking chamber is exhausted, the 3 rd valve is operated to reduce the opening degree, the 1 st valve is operated to open and circulate, carrier gas is conveyed into the baking chamber to increase the air pressure of the baking chamber, and when the measured value fed back by the vacuum gauge reaches the set value of the baking vacuum degree obtained from the baking process, the baking device is operated to start heating; acquiring a measured value of the temperature detected by the 1 st temperature sensor and a set value of the baking temperature from the baking process, operating the baking device to adjust and heat so that the measured value of the temperature reaches the set value, baking the food in a vacuum environment with carrier gas according to the baking temperature set in the baking process until the baking is finished; after the baking is started, the 2 nd valve and the 5 th valve can be operated to open and circulate, the carrier gas discharges the air in the cooling chamber to obtain the measured value fed back by the oxygen sensor, and when the measured value is smaller than the evacuation reference value in the baking process, the judgment that the air in the cooling chamber is completely discharged is made, so that the method is suitable for operating the 2 nd valve and the 5 th valve to adjust the opening of the small valve and moving the food waiting for being baked into the baking chamber; when the food is baked, the 3 rd valve is operated to be closed, the vacuum pump is operated to be stopped, when the measured value fed back by the vacuum gauge reaches a preset pressure value, if the pressure of the cooling chamber is equivalent to that of the baking chamber, the 2 nd gate is operated to be opened, the baking device and the cooling device are operated to transfer the baked food into the cooling chamber, the 2 nd gate is operated to be closed, the 4 th valve is operated to be opened for circulation, the circulating pump is operated to be started, carrier gas in the cooling chamber flows in a circulating manner, the food is cooled in circulating airflow formed by the carrier gas, the measured value of the 2 nd temperature sensor and the set value of the cooling temperature are obtained, and the opening degree of the 4 th valve is operated to adjust the valve so that; and finishing the baking of the food until the temperature measurement value fed back by the 2 nd temperature sensor is less than the set value in the baking process.

Compared with the prior art, the invention has the following beneficial technical effects.

The food is baked in a vacuum environment with carrier gas, and the crispness uniformity of the food are improved; the carrier gas timely discharges baking volatile matters such as oil volatilized from the food, trace metal ion gas volatilized from the baking chamber and the like and leaked air, and the oil in the food is difficult to generate high-temperature oxidation and metal-catalyzed hydrogen peroxide reaction to generate oxidation metamorphic substances; the content of oil oxidation metamorphic substances in the food is less than 10 percent of that of the conventional baked food, the oxygen absorption capacity of the food is greatly reduced, and the oxygen residual quantity in the food is extremely low, so that the baked food is easier to store, and the shelf life of the baked food is improved by 0.5-1 time or even longer; the content of the oil oxidation deterioration matter in the food is low, which is more beneficial to the health of eaters.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.

Fig. 1 is a schematic view of a food vacuum cooking apparatus in an embodiment.

Fig. 2 is a schematic view of a gas supply device.

FIG. 3 is a schematic view of the toasting apparatus.

FIG. 4 is a schematic sectional view taken along the line A-A of the roasting apparatus of FIG. 3.

FIG. 5 is a schematic view of another toasting apparatus.

FIG. 6 is a schematic view of a vacuum apparatus.

Fig. 7 is a schematic bottom view of the air distribution head of fig. 3.

FIG. 8 is a bottom view of the flow equalization grid of FIG. 3.

Fig. 9 is a schematic bottom view of the assembled flow equalization grid and gas distribution header.

FIG. 10 is a schematic top view of the air capture head of FIG. 3.

Fig. 11 is a schematic top view of the interference grid of fig. 3.

FIG. 12 is a schematic top view of the assembled interference grating and air capture head.

Fig. 13 is a schematic view of the structure of the cooling device.

Fig. 14 is a schematic view of the cooling device in fig. 13 in a sectional view in the direction B-B.

Fig. 15 is a schematic bottom view of a cold air shower head.

Wherein, 10 conveying devices, 20 baking devices, 21 baking belts, 22 air distributing heads, 221 shunting pipes, 222 air guiding pipes, 223 air nozzles, 23 flow equalizing grids, 231 transverse flow equalizing plates, 232 longitudinal flow equalizing plates, 233 flow blocking plates, 24 air trapping heads, 241 flow guiding cavities, 242 air trapping holes, 25 interference blocking grids, 251 transverse interference blocking plates, 252 longitudinal interference blocking plates, 253 flow limiting plates, 26 first gates, 27 second gates, 2 gates, 30 cooling devices, 31 cold supporting belts, 32 cold air sprinkling heads, 321 cold air cavities, 322 cold air nozzles, 33 exhaust air trapping buckets, 34 second gates, 3 air supplying devices, 41 air storage tanks, 42 gasifiers and 43 temporary storage tanks, 44-pressure reducing valve, 50-vacuum device, 51-filter, 52-vacuum pump, 60-circulating device, 61-heat exchanger, 62-circulating pump, 71-vacuum gauge, 72-1 st temperature sensor, 73-oxygen sensor, 74-2 nd temperature sensor, 81-1 st valve, 82-2 nd valve, 83-3 rd valve, 84-4 th valve, 85-5 th valve.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. The directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the movement, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indication is changed accordingly.

As an embodiment of the present application, a food vacuum baking apparatus for advantageously improving crispness of food is provided, as shown in fig. 1, 13 and 15, and comprises a conveying device 10, a baking device 20, a cooling device 30, an air supply device 40, a vacuum device 50, a circulation device 60, a sensor group and a valve group, and a pipeline. The sensor group comprises a vacuum gauge 71, a 1 st temperature sensor 72, an oxygen sensor 73 and a 2 nd temperature sensor 74; the valve group includes a 1 st valve 81, a 2 nd valve 82, a 3 rd valve 83, a 4 th valve 84, and a 5 th valve 85. The conveyor 10 is adapted to temporarily store and transfer the food to be toasted into a toasting chamber of a toasting device 20, the toasting device 20 being adapted to toast the food in a vacuum environment with a carrier gas; the cooling device 30 is adapted to cool the food product in an environment of carrier gas; the gas supply means 40 is adapted to supply a carrier gas into the baking chamber of the baking means 20, which carrier gas is adapted to carry baking volatiles and leaked air out in time, and to supply a carrier gas into the cooling chamber of the cooling means 30, cooling the food in a carrier gas environment, cooling the food at normal pressure; the vacuum device 50 is adapted to provide a vacuum environment, i.e., vacuum conditions, required by the toasting device to toast the food product; the circulation device 60 is adapted to circulate the carrier gas within the roasting chamber to cool the food. The output port of the conveying device 10, which is suitable for outputting the food, is communicated with the input product of the baking device 20, which is suitable for inputting the food, in a sealing manner; the food product outlet of the grilling unit 20 adapted for the output of food product is in sealed communication with the food product inlet of the chilling unit 30 adapted for the input of food product. A1 st gate 26 is provided at the food input port of the toasting device 20 in a sealed manner, as shown in FIG. 3, adapted to isolate the conveyor 10 from the toasting device 20; a 3 rd shutter 34 is provided in a sealed manner at the food output of the cooling device 30, adapted to isolate the cooling chamber from the air; a2 nd gate 27 is arranged between the food output port of the baking device 20 and the food input port of the cooling device 30 in a sealing manner and is suitable for isolating the baking chamber of the baking device 20 from the cooling chamber of the cooling device 30, the baking device 20 bakes food in a vacuum environment with carrier gas, and the cooling device 30 cools food in a carrier gas environment with normal pressure. The baking of the food is carried out in a vacuum environment with carrier gas, the transfer of the food in the baking equipment and the cooling of the food are carried out in the carrier gas environment, the food is isolated from the air, the condition that the grease in the food is contacted with the air and is oxidized in a high-temperature period to generate grease oxidation degeneration substances such as trans-fatty acid which are harmful to health is effectively avoided, the oxygen absorption capacity of the food is improved, and the shelf life of the food is too short. When the food is baked in a vacuum environment, the air pressure born by the surface of the food is very small, the food is favorable for expansion and puffing, and the crispness of the baked food is obviously improved.

The conveying device 10, as shown in fig. 1, is adapted to temporarily store and transfer the food to be baked. The conveyor 10 is equipped with a mesh-belt type conveyor mechanism adapted to carry and transfer the food products, as shown in fig. 1, and further, the exterior of the conveyor 10 is provided with a hermetically sealable housing for isolation from air. The interior of the conveying device 10 is conveyed with carrier gas, such as nitrogen, to exhaust the air in the conveying device 10, so that the food to be baked is isolated from the air, and the food to be baked is temporarily stored and transferred in the carrier gas environment, which is beneficial to reducing the oxidation of grease in the food. The drive means of the transport mechanism, such as a motor, may be mounted outside the housing, as is known in the art and will not be described in detail.

As shown in fig. 1, 3 and 4, the baking device 20 includes a casing capable of achieving sealing, a baking chamber suitable for baking food is disposed in the casing, and a heat insulation layer (not shown) is disposed between the baking chamber and the casing. One side, e.g. the left side, of the toasting device 20 is provided with an inlet opening adapted to be moved in by the food to be toasted, at which inlet opening a 1 st gate 26 is arranged in a sealing manner. The food input port of the toasting device 20 is in sealed communication with the food output port of the conveyor 10, and the 1 st gate 26 isolates the conveyor 10 from the toasting device 20. The other side of the grilling apparatus 20, i.e. the right side, is provided with an outlet opening adapted to remove the grilled food product, wherein a 2 nd gate 27 is sealingly arranged at the outlet opening, wherein the food outlet opening of the grilling apparatus 20 is sealingly connected to the food inlet opening of the cooling apparatus 30, wherein the 2 nd gate 27 isolates the cooling apparatus 30 from the grilling apparatus 20 and is adapted to isolate the food product to be grilled from the air, wherein a vacuum environment is formed in the grilling chamber, which is required for grilling the food product, and wherein the food product is grilled in a vacuum environment with a carrier gas. It should be noted that the 2 nd gate 27 can also be disposed between the cooling device 30 and the baking device 20 in a sealing manner, and can also be disposed at the food input port of the cooling device. The baking chamber of the baking device 20 is provided with a baking support belt 21 which is arranged along the horizontal direction and is suitable for carrying food to be baked, an air distribution head 22 which is suitable for guiding the carrier gas to flow to the baking support belt 21 in a shunting way, and an air capture head 24 which is suitable for discharging the carrier gas. The air distributing head 22 is horizontally arranged along the horizontal plane and is positioned above the baking belt 21, and the air capturing head 24 is horizontally arranged along the horizontal plane and is positioned below the baking belt 21. The air distribution head 22, the baking support belt 21 and the air capture head 24 are arranged in parallel and are opposite in the vertical direction, namely the air distribution head 22 is arranged right above the baking support belt 21 and the air capture head 24 is arranged right below the baking support belt 21. Heaters (not shown) are respectively provided at the upper and lower sides of the grill belt 21, i.e., an upper heater and a lower heater, and are suitable for uniformly roasting food. The roasting device is provided with a 1 st temperature sensor 72 adapted to detect the temperature of the food to be roasted, which can be understood as detecting the roasting temperature of the food to be roasted, and an oxygen sensor can be further provided in the exhaust duct of the roasting device for determining whether the air in the roasting chamber is completely exhausted and whether the air leaks into the roasting chamber. Specifically, the measured value fed back by the oxygen sensor is compared with the set value of the evacuation reference value, and when the measured value is smaller than the evacuation reference value, a judgment can be made that the air in the oven chamber is completely exhausted or no air leaks, otherwise, a judgment can be made that the air in the oven chamber is not completely exhausted or air leaks. The baking belt 21 may be a steel belt with mesh holes, or a mesh belt, or any kind of flexible bearing member suitable for bearing moon cakes and allowing the carrier gas to freely flow from top to bottom, in other words, the baking belt 21 does not block the upward and downward free flow of the carrier gas (such as nitrogen). The driving mechanism of the baking device 20, which is suitable for driving the baking belt 21 to move, is located in the baking chamber housing, and the driving device of the driving mechanism, such as a motor, may be located outside the housing, which are all the prior art and will not be described in detail.

The cooling device 30, as shown in fig. 1, 13 and 14, includes a housing that can be sealed, and is adapted to cool food to be cooled in an environment of carrier gas isolated from air, and a cooling chamber for cooling food is provided in the housing. The cooling chamber is internally provided with a cold supporting belt 31, a cold air sprinkling head 32 and an exhaust trapping bucket 33. Further, heaters (not shown) adapted to adjust the cooling rate of the food can be disposed in the cooling chamber and distributed on the upper and lower sides of the cold carrier strip 31. The cold carrying belt 31 is horizontally arranged in the horizontal plane direction in the cooling chamber, and mesh holes suitable for the circulation of the carrier gas are arranged on the cold carrying belt 31. The cold air sprinkling head 32 is arranged right above the cold supporting belt 31 and is arranged in parallel with the cold supporting belt 31, the cold air nozzle 322 on the bottom end surface of the cold air sprinkling head 32 is opposite to the cold supporting belt 31, and the carrier gas flowing out of the cold air nozzle 322 forms cold air flow which flows to the food on the cold supporting belt 31 to take away the heat of the food. The outlet port of the air trapping funnel 33 adapted to discharge the carrier gas is in sealed communication with an exhaust duct provided in the cooling device, in which an oxygen sensor 73 is fitted, as shown in fig. 13, adapted to judge whether or not the air in the cooling chamber is completely discharged or whether or not the air leaks into the cooling chamber. Specifically, the measurement value fed back by the oxygen sensor 73 is compared with the evacuation reference value in the baking process, and when the measurement value is smaller than the evacuation reference value, a judgment can be made that the air in the cooling chamber is completely discharged or has no air leakage, otherwise a judgment can be made that the air in the cooling chamber is not completely discharged or has air leakage. The exhaust trapping bucket 33 is arranged right below the cold supporting belt 31, is horizontally arranged along the horizontal plane direction, is distributed in parallel with the cold supporting belt 31, and is positioned at the exhaust opening of the top end face of the exhaust trapping bucket 33 and is right opposite to the cold supporting belt 31. One side, e.g. the left side, of the cooling device 30 is provided with a food product inlet opening adapted for the food product to be cooled to be moved in, at which opening a gate is arranged in a sealed manner, which in this embodiment shares the 2 nd gate 27 of the toasting device 20, in order to isolate the cooling device 30 from the toasting device 20. The other side of the cooling device 30, e.g. the right side, is provided with a food outlet adapted to remove the finished cooled food product, at which outlet a 3 rd gate 34 is arranged in a sealed manner to isolate the packaging device in sealed communication with the food outlet of the cooling device 30.

The cold supporting belt 31 is used for transferring food to be cooled into the cooling chamber, and carrying the food to be cooled in a carrier gas environment. The cold carrier belt 31 may be a mesh belt, a steel belt, or any kind of flexible carrier suitable for supporting food and allowing the free flow of air upward and downward. The cooling device 30 is provided with a driving mechanism adapted to drive the cold carrying belt 31 to move for transferring the food, and a driving device of the driving mechanism, such as a motor, can be disposed outside the cooling chamber and inside the housing, and is of an integrated structure, which is prior art and will not be described in detail.

As shown in fig. 2, the gas supply device 40 includes a gas storage tank 41, a vaporizer 42, a temporary storage tank 43, and a pressure reducing valve 44. The gas storage tank 41 is adapted to store a liquid carrier gas, such as high purity nitrogen, optionally food grade liquid nitrogen of purity up to analytical grade. The vaporizer 42 is adapted to endothermically vaporize the liquid nitrogen to form gaseous nitrogen; the pressure reducing valve 44 is adapted to change the higher pressure nitrogen gas to a lower pressure stable nitrogen gas. The output port of the gas storage tank 41, which is suitable for the outflow of liquid nitrogen, is communicated with the input port of the gasifier 42 through a liquid nitrogen pipeline, and a flow regulating valve is arranged in the liquid nitrogen pipeline between the gas storage tank 41 and the gasifier 42 to regulate the flow of the liquid nitrogen and regulate the output quantity of the nitrogen, so that the nitrogen is matched with the demand quantity, and the over-high pressure of the nitrogen is avoided. The outlet of the vaporizer 42, through which the nitrogen gas flows out, and the inlet of the buffer tank 43, through which the carrier gas flows in, are in sealed communication via a pipe. The output port of the temporary storage tank 43, which is suitable for the outflow of the carrier gas, is in sealed communication with the input port of the pressure reducing valve 44 through a pipe, and the output port of the pressure reducing valve 44 is suitable for delivering the nitrogen carrier gas into the baking chamber of the cooling device 30. The use of the temporary storage tank 43 makes the supply pressure of the carrier gas more stable. The nitrogen is food grade nitrogen with purity reaching analytical purity, and food grade nitrogen with purity reaching 99% or more can be selected, and the nitrogen can be understood as the high-purity nitrogen. The nitrogen may also be replaced by argon or helium, hereinafter collectively referred to as carrier gas.

Wherein, the vacuum device 50 is suitable for providing a vacuum environment required by food baking. As shown in fig. 1 and 6, the vacuum apparatus 50 includes a filter 51 and a vacuum pump 52. The filter 51 is adapted to filter out oil mist and particulate matter mixed in the carrier gas discharged from the roasting chamber of the roasting apparatus, and the vacuum pump 52 is adapted to maintain a vacuum environment, i.e., a vacuum condition, required for roasting food in the roasting chamber of the roasting apparatus. The input port of the filter 51 suitable for the input of the carrier gas is communicated with the output port of the gas trapping head 24 suitable for the output of the carrier gas in a sealing way through an air extraction pipeline, and the air extraction pipeline can be a metal corrugated pipe. The oxygen sensor of the baking device can be arranged in the air exhaust pipeline and is suitable for detecting the oxygen content of the exhausted carrier gas so as to judge whether the air in the baking chamber is completely exhausted or whether the air leaks into the baking chamber.

Wherein, the circulating device 60 is adapted to drive the carrier gas in the cooling chamber to circulate and flow so as to cool the food. The circulation device 60, as shown in fig. 1 and 13, includes a heat exchanger 61 and a circulation pump 62. The heat exchanger 61 is suitable for exchanging heat between the carrier gas with higher temperature flowing out of the cooling chamber and air to cool down the carrier gas to form carrier gas with lower temperature, and the circulating pump 62 is suitable for sucking the carrier gas with lower temperature into the cooling chamber. The inlet of the heat exchanger 61 adapted to the input of the carrier gas communicates in a sealed manner with the outlet of the exhaust duct in the cooling device via a duct in which a 4 th valve 84 is fitted, the 4 th valve 84 being located on the inlet side of the heat exchanger 61. The output port of the heat exchanger 61 suitable for outputting the carrier gas is communicated with the input port of the circulating pump 62 suitable for inputting the carrier gas in a sealing mode through a pipeline, and the output port of the circulating pump 62 suitable for outputting the carrier gas is communicated with the input port of the cold air sprinkler suitable for inputting the carrier gas in a sealing mode through a gas transmission pipeline. The exhaust trapping bucket, the heat exchanger, the circulating pump and the cold air sprinkling head form a circulating flow path for circulating the carrier gas of the cooling chamber, and the flow rate of the carrier gas of the circulating flow path can be adjusted through the opening degree of the 4 th valve 84 so as to adjust the speed of cooling the food. An exhaust bypass communicated with the pipeline between the output port of the exhaust pipeline in the cooling device and the 4 th valve 84 is arranged in the pipeline, as shown in fig. 13, and is suitable for exhausting the cooling device outwards, so that the carrier gas conveyed by the gas supply device gradually replaces part of the circulating carrier gas, and the oxygen content of the carrier gas in the cooling chamber is further reduced. A 5 th valve 85 is provided in the exhaust bypass for controlling the flow of the exhaust bypass, blocking the flow and exhaust flow. The heat exchanger 61 and the circulation pump 62 may be disposed outside the cooling device 30 to form a separate structure; the heat exchanger 61 and the circulation pump 62 may be integrated with the cooling device 30 to form an integrated structure.

The carrier gas in the cooling chamber is discharged from the exhaust trapping bucket 33 into the heat exchanger 61 through the exhaust pipeline, forms carrier gas (called cold wind for short) with lower temperature after heat exchange and temperature reduction through the heat exchanger 61, is sucked by the circulating pump 62 to apply force, the cold carrier gas with lower temperature flows into the cold wind shower head 32 and is shunted in the cold wind cavity 321, the cold carrier gas respectively flows downwards from the cold wind nozzle 322 on the lower end surface of the cold wind cavity 321 and flows towards the food on the cold support roast 31, the carrier gas with lower temperature flows downwards from top to bottom, smooths the food, changes the heat emitted by the food into carrier gas with higher temperature, the carrier gas flows downwards through the mesh holes on the cold support belt 31, the carrier gas with higher temperature flows towards the opening at the top end of the exhaust trapping bucket 33, the carrier gas flows into the heat exchanger 61 through the exhaust trapping bucket 33 and the exhaust pipeline, the carrier gas with higher temperature exchanges heat and reduces temperature through the, the cold carrier gas is pumped by the circulating pump 62 to apply force to flow back into the cold air sprinkling head 32, then flows out through the cold air nozzle on the cold air sprinkling head 32 and flows towards the food to be cooled, the carrier gas in the cooling chamber circulates in such a way, carries the heat of the food, and the food is cooled until the temperature of the food is reduced to the process temperature.

Further, the gas distribution head 22 has a planar plate-like structure, and is horizontally arranged along the horizontal plane direction as shown in fig. 3, 4, and 5. The gas distribution header 22, as shown in fig. 4 and 7, includes a shunt pipe 221 adapted to shunt the input carrier gas, and a plurality of flow guide pipes 222 arranged horizontally in a horizontal plane and parallel to each other, wherein the flow guide pipes 222 are arranged horizontally. The dividing tube 221 is provided with an input port at the upper end for inputting the carrier gas and a plurality of output ports at the lower end communicated with the input port, and is used for dividing the input carrier gas uniformly and respectively transmitting the divided gas to each flow guide tube 222. The flow conduit 222 is provided with an input port at its top end adapted for the input of a carrier gas. The input port of each flow guide tube 222 suitable for gas input and the output port of the flow dividing tube 221 are respectively communicated in a sealed manner, a plurality of gas nozzles 223 are arranged on the lower end face of the flow guide tube 222, the gas outlets of the gas nozzles 223 are opposite to the baking support belt 21, and the gas nozzles are suitable for dividing the carrier gas in the flow guide tube 222 and guiding the carrier gas to flow to the baking support belt 21 so as to timely take away volatile substances volatilized by the food on the baking support belt 21 and trace metal ion gas volatilized at high temperature in the baking chamber, and discharge the volatile substances and the trace metal ion gas outwards, so that the oxidation of grease in the food. The output port of the pressure reducing valve 44 of the gas supply device 40 is hermetically communicated with the input port of the shunt pipe 221 through a gas transmission pipeline, and the 1 st valve 81 is assembled in the gas transmission pipeline and used for controlling the gas supply device 40 to input the carrier gas into the baking chamber of the baking device 20, stopping conveying the carrier gas and adjusting the conveying flow of the carrier gas. The flow-guide tubes 222 are arranged transversely along the horizontal plane and are uniformly distributed at equal intervals along the longitudinal direction, as shown in fig. 4 and 7, each flow-guide tube 222 is respectively communicated with an input port at the top end of the gas-distributing head 22 and is suitable for distributing the carrier gas into each flow-guide tube 222. The air nozzle 223 is arranged on the bottom end surface of the guide pipe 222, the air nozzle 223 is communicated with the guide pipe 222, the air nozzles 223 on each guide pipe 222 can be used for providing a plane, the air outlets of the air nozzles 223 are opposite to the baking support belt 21 and cover the baking support belt 21, carrier gas in the guide pipe 222 is suitable for being blown to the baking support belt 21 through the air nozzles 223, and carrier gas flow is uniformly distributed and respectively flows to each piece of food on the baking support belt 21. The air nozzles 223 communicated with the flow guiding tube 222 are distributed along the direction (i.e. transverse direction) of the flow guiding tube 222 at equal intervals, as shown in fig. 7, so as to uniformly distribute the carrier gas, and make the distribution of the carrier gas flow more uniform. Furthermore, the middle part of the flow guide pipe 222 is provided with an input port suitable for inputting carrier gas, which is beneficial to reducing pressure drop difference in the flow guide pipe 222, so that the flow rate and the flow velocity of the carrier gas flowing out from each air nozzle 223 are equivalent, the uniformity of the distribution of the carrier gas flow is improved, food is beneficial to being uniformly baked and air-dried, the consistency of the quality of the food, such as walnut cakes, biscuits, dried purple sweet potatoes, potato chips and the like, is ensured, such as the crispness and the crispness uniformity are improved, and the crispness and the mouth feel are better.

Further, the air trapping head 24 has a planar plate-like structure, and as shown in fig. 3, 4, and 5, the air trapping head 24 has a thin-walled housing structure, and may have a block shape. The top end surface of the gas trapping head 24 is provided with a plurality of annular gas trapping holes 242 suitable for the inflow of the carrier gas, a flow guide cavity 241 horizontally arranged along the horizontal plane is arranged inside the gas trapping head, and the bottom end surface is provided with an exhaust port 243 suitable for being connected with an exhaust pipeline, as shown in fig. 3 and 10. The air trapping holes 242 are preferably circular, and when the vacuum degree in the oven chamber is low, such as at the initial stage of vacuum pumping, it is beneficial to reduce the generation of rotational flow at the air trapping holes 242 during the vacuum pumping, so that the carrier gas airflow in the oven chamber is uniformly distributed. The air outlet 243 of the air trapping head 24 is communicated with one end of an air exhaust pipeline of the baking device, the other end of the air exhaust pipeline is communicated with the input port of the filter 51 of the vacuum device in a sealing mode through an air exhaust pipeline, the air exhaust pipeline is suitable for the vacuum device to vacuumize the baking chamber, and a 3 rd valve 83 which is suitable for controlling vacuumizing and blocking vacuum-pumping capacity and changing the opening degree of the valve to adjust the vacuum degree of the baking chamber is arranged in the air exhaust pipeline. The air trapping holes 242 are arranged on the top end face of the air trapping head 24 and communicated with the flow guide cavity 241, the air trapping holes 242 are uniformly distributed along the longitudinal direction and the transverse direction, as shown in fig. 10, the air trapping holes 242 are distributed in rows and columns, and are distributed at equal intervals from row to row and are distributed at equal intervals from column to column. The air inlets of the air trapping holes 242 are arranged opposite to the baking belt, so that the carrier gas flowing from top to bottom can conveniently flow into the air trapping holes. The carrier gas is adopted, so that trace metal ion gas volatilized from the baking device 20 at high temperature can be taken out of the baking chamber in time, and oil volatilized from food at high temperature can be taken out of the baking chamber in time, namely, the baked volatile matter can be taken out of the baking chamber in time through the carrier gas vacuum device, so that the metal-catalyzed hydrogen peroxide reaction of the oil in the food can be further reduced, and the generation of harmful oxidized and deteriorated substances can be reduced. It should be noted that, when the requirement on the baking uniformity is not high, the air trapping head 24 may be replaced by a funnel-shaped air exhausting device, as shown in fig. 5, or may be directly exhausted by an air exhausting hole.

Further, the cold air shower head 32 is a planar plate-shaped housing structure, as shown in fig. 13 and 14, the cold air shower head 32 is horizontally arranged along a horizontal plane, and an area of the cold air shower head can cover the cold supporting belt 31 and is located right above the cold supporting belt 31. The cold air shower head 32 may be a thin-walled housing structure, as shown in fig. 13 and 15, an input port adapted to inflow of carrier gas and circulating carrier gas (i.e., cold air) is disposed at a middle portion of a top end surface of the cold air shower head 32, a cold air chamber 321 adapted to circulation of cold air and diversion of carrier gas is disposed inside the cold air shower head, a cold air nozzle 322 adapted to outflow of cold air in the cold air chamber 321 is disposed on a bottom end surface of the cold air shower head, an output port of the cold air nozzle 322 is disposed downward, and the cold air chamber 321 is horizontally disposed in a horizontal. The air delivery opening in the middle of the top end face of the cold air shower head 32 is communicated with the output opening of the circulating pump 62 through a pipeline. As shown in fig. 15, the cold air nozzles 322 are respectively and uniformly distributed on the bottom end surface of the cold air shower head 32 at equal intervals in the transverse direction and at equal intervals in the longitudinal direction, the cold air outlets of the cold air nozzles 322 are arranged downward and are opposite to the cold holding strip 31, and the cold air flowing out of the cold air nozzles 322 flows toward the food placed on the cold holding strip 31. The cold air sprinkling head 32 shunts the carrier gas and the circulating carrier gas and guides the carrier gas to flow to the cold supporting belt 31, the carrier gas flow is uniformly distributed, the heat of each food carried away by the carrier gas flow is the same, the constant-speed temperature reduction and constant-speed moisture volatilization of each food are facilitated, the quality of the food is improved, the good crispness and crispness uniformity of the food are kept, and the taste is facilitated to be improved.

Further, the exhaust trapping bucket 33 is, as shown in fig. 14, a funnel-shaped structure surrounded by side walls, an opening at a top end of the exhaust trapping bucket is suitable for the carrier gas to flow in, an output port suitable for the carrier gas to flow out is arranged at a lower end of the exhaust trapping bucket, and the output port is communicated with an input port of the heat exchanger 61 through an exhaust duct. The pressure of the cooling chamber is adjusted by adjusting the opening of the 2 nd valve 82 to adjust the input flow of the carrier gas and adjusting the opening of the 4 th valve 84 to adjust the flow of the circulating carrier gas, so that the pressure of the cooling chamber is slightly larger than the atmospheric pressure, and the cooling chamber keeps positive pressure, thereby effectively avoiding air infiltration and reducing the content of food oil oxidation degeneration. The top opening of the exhaust trapping bucket 33 is just opposite to the cold supporting belt 31, the area of the top opening is larger than that of the cold supporting belt 31, the top opening of the exhaust trapping bucket 33 completely covers the cold supporting belt 31, the carrier gas can flow into the exhaust trapping bucket 33 and flow into the heat exchanger 61 through the exhaust pipeline, and more importantly, the phenomenon that the carrier gas forms turbulent flow below the cold supporting belt 31 and influences the uniformity of carrier gas airflow distribution above the cold supporting belt 31 can be avoided, so that the food is uniformly cooled, and the consistency of crispness of the food is ensured.

Before baking the food, a baking process corresponding to the food needs to be established so as to operate the food vacuum baking equipment to bake the food. The baking process comprises presetting a set value of vacuum degree, a set value of an evacuation reference value, and set values of carrier gas parameters, baking vacuum degree, baking temperature and cooling temperature which are associated with time. The carrier gas parameters comprise set values of a vacuum pump start-stop state, a circulating pump start-stop state, a 1 st valve opening-closing and opening state, a 2 nd valve opening-closing and opening state, a 3 rd valve opening-closing and opening state, a 4 th valve opening-closing and opening state and a 5 th valve opening-closing and opening state. The preset vacuum degree can be used for representing the high vacuum degree required by vacuum boiling puffing treatment of food to be baked before baking, and can also be used for judging a reference value for completely discharging air in a cooling chamber, if the value can be 50 Pa, water in the food is boiled and gasified at normal temperature. The food vacuum boiling puffing treatment step is an optional baking process, so that the crispness of baked food can be improved, and the food is more crispy and has better mouthfeel.

The No. 1 gate 26 of the baking device 20 is operated to be opened, the conveying device 10 and the baking device 20 are operated to transfer the food to be baked into the baking chamber of the baking device 20, and the No. 1 gate 26 is operated to be closed. Based on the set baking process, the baking equipment is controlled to perform vacuum boiling puffing treatment (which is an optional process) on the food to be baked, then the food is baked in a vacuum environment with carrier gas, and the food is cooled in a carrier gas environment. Specifically, the method comprises the following steps: the 3 rd valve 83 is operated to circulate, the vacuum pump of the vacuum device is operated to start, air in the baking chamber of the baking device is sucked and exhausted, and the baking chamber is vacuumized to obtain the vacuum condition required for baking food. The method is suitable for obtaining a measured value of a vacuum gauge 71, when the measured value fed back by the vacuum gauge 71 is smaller than a preset vacuum degree in a baking process, namely a high vacuum condition required for vacuum boiling puffing pretreatment of food before baking is carried out, for example, the vacuum degree reaches 50 Pa, moisture contained in the food is boiled, gasified and expanded at room temperature, the surface pressure of the food is low and close to zero, gas is formed in the food and is gasified and expanded in vacuum, the puffing rate of the food is improved, and the food is kept for a preset time period under the vacuum condition to be fully gasified and expanded, so that the baked food is crisp and has better crisp uniformity. After the food is pretreated by vacuum boiling and puffing, the 1 st valve 81 is operated to flow and convey carrier gas into the baking chamber, so that the vacuum degree of the baking chamber is reduced, and when the measured value fed back by the vacuum gauge 71 reaches the set value of the baking vacuum degree obtained from the baking process, such as 1000 or 1500 Pa, the baking device 20 is operated to start heating, and the food is baked in a vacuum environment with the carrier gas. The measured value of the temperature detected by the 1 st temperature sensor 72 and the set value of the baking temperature obtained from the baking process are obtained, the baking device 20 is operated to adjust the heating so that the measured value of the temperature reaches the set value, and the food is baked in the vacuum environment at the set baking temperature until the baking of the food is completed. After the baking is started, the 2 nd valve 82 can be operated to convey the carrier gas into the cooling chamber of the cooling device 30, the 5 th valve 85 can be operated to open the circulation to exhaust the gas outwards, and the air in the cooling chamber is exhausted; when it is judged that the air in the cooling chamber is completely discharged based on the measurement value fed back from the oxygen sensor 73, the 2 nd valve 82 is operated to reduce the valve opening degree, and the food is waited to be moved in. During baking, the carrier gas can timely bring the trace metal ion gas volatilized at high temperature in the baking chamber out of the baking chamber and timely bring the oil volatilized at high temperature in the food out of the baking chamber, so that high-temperature oxidation and metal-catalyzed hydrogen peroxide reaction of the oil in the food can be further reduced, and the generation of oxidation deterioration substances harmful to health is reduced. After the food is completely baked, the 3 rd valve 83 is operated to be closed, the vacuum pump 52 is operated to be stopped, when the measured value fed back by the vacuum gauge 71 reaches the set pressure value, such as the standard atmospheric pressure, the 2 nd gate 27 is operated to be opened, the baking device 20 and the cooling device 30 are operated to transfer the baked food into the cooling chamber, and the 2 nd gate 27 is operated to be closed; based on the baking process, the 4 th valve 84 is operated to open and circulate, the circulating pump 62 is operated to start, the carrier gas in the baking chamber circularly flows to exchange heat, and the baked food is cooled in the circulating airflow formed by the carrier gas; acquiring a temperature measurement value fed back by the 2 nd temperature sensor 74 and a set value of cooling temperature acquired from the baking process, operating the 4 th valve 84 to adjust the valve opening, adjusting the valve opening to be smaller when the temperature measurement value is smaller than the set value, and otherwise, adjusting the valve opening to be larger so that the temperature measurement value is consistent with the set value, and cooling according to the set temperature in the baking process; the cooling of the food is completed until the temperature measurement value fed back by the 2 nd temperature sensor 74 is less than the set value in the baking process, and the baking of the food is completed. The food is baked in a vacuum environment with carrier gas, the air pressure born by the food is small, the food is not easy to harden, and the crispness uniformity of the baked food can be obviously improved; before baking, the food to be baked is subjected to vacuum boiling puffing treatment, water in the food is boiled and gasified, air holes in the food are expanded and puffed, the puffing rate of the food is improved, the crispness of the baked food is further remarkably improved, and the hardness of the food can be reduced by more than 15%. The carrier gas discharges volatile oil of food, volatile trace metal ion gas and other baking volatile matters in the baking chamber in time, the oil in the food is difficult to generate oxidation reaction, the oxidation degradation matters and oxygen residual quantity of the oil in the food are less, the food is favorably stored, and the shelf life of the food can be prolonged by 0.5-1 time or even longer. The food has low content of lipid oxidation deterioration substances, and is beneficial to health.

Further, in order to avoid the turbulence generated by the carrier gas flowing out from the air nozzle 223, so that the carrier gas flow is uniformly distributed, and the consistency of the food quality, particularly the crispness and uniformity, is ensured, a flow equalization grid 23 suitable for equalizing and stabilizing the flow is required to be arranged between the gas distribution head 22 and the baking belt 21, and the flow equalization grid 23 and the gas distribution head 22 are fixed. The flow equalization grid 23, as shown in fig. 3, 4 and 8, includes a transverse flow equalization plate 231 and a longitudinal flow equalization plate 232. The transverse flow equalizing plates 231 are uniformly distributed at equal intervals along the longitudinal direction as shown in fig. 3 and 8, and the transverse flow equalizing plates 231 are perpendicular to the horizontal plane, that is, perpendicular to the bottom end surface of the gas distributing head 22, which can be understood as that the transverse flow equalizing plates 231 are arranged along the vertical direction; the longitudinal flow equalizing plates 232, as shown in fig. 3 and 9, are uniformly distributed along the transverse direction at equal intervals, and the longitudinal flow equalizing plates 232 are perpendicular to the horizontal direction, i.e., perpendicular to the bottom end surface of the gas distribution head 22, which can be understood as that the longitudinal flow equalizing plates 232 are arranged along the vertical direction. The transverse flow equalizing plate 231 and the longitudinal flow equalizing plate 232 penetrate and are fixed with each other to form a grid structure in a shape of a Chinese character 'jing', the grid structure is suitable for forcing carrier gas flowing out of the air nozzles 223 to flow downwards along grids of the flow equalizing grid, food is blown and shot, the carrier gas flowing out of the air nozzles 223 is prevented from generating components flowing in the horizontal direction, even turbulence is generated, the flow field distribution of the carrier gas is enabled to be more uniform, the uniformity of the quality of baked food in a carrier gas environment is ensured to be better, such as color uniformity and crisp uniformity, the taste is improved, and the phenomenon that some food is too hard and bad in taste is avoided. In order to overcome the disturbance effect of the baking chamber wall of the baking device 20 on the carrier gas flow, baffles 233 are respectively disposed at the peripheral sides of the flow equalizing grid 23, as shown in fig. 3 and 8, the baffles 233 are arranged in the vertical direction, and the lower ends of the baffles 233 are inclined outward (i.e., with respect to the middle of the flow equalizing grid 23) with respect to the upper ends. Four spoilers 233 located on four sides of the flow equalization grid 23 are connected end to end in sequence to form a skirt-like structure, as shown in fig. 3, the inner diameter of the opening at the lower end of the skirt-like structure is larger than that of the opening at the upper end. Further, based on a large amount of practical data analysis, when the lower end of the baffle 233 is inclined outward by 11-18 degrees, particularly 13-14 degrees, in the vertical direction, the influence of the baking chamber wall of the baking device on the uniform distribution of the airflow of the air distribution head 22 is minimal, no obvious turbulence is formed on the periphery of the air distribution head 22, the distribution of the carrier airflow flowing out of the air distribution head 22 is more uniform, and the crisp uniformity of the food is improved.

Further, in order to reduce the disturbance influence of the carrier gas suction by the gas trapping head 24 on the uniform distribution of the carrier gas flow, destroy the uniformity of the distribution of the carrier gas flow, and ensure the consistency of the food quality, particularly the crispness uniformity, it is necessary to provide a disturbance barrier 25 between the baking belt 21 and the gas trapping head 24, as shown in fig. 3 and 11. The interference prevention grille 25 is fixed with the air trapping head 24, is close to one side of the baking support belt 21 and is positioned right above the air trapping head 24. The interference grid 25, as shown in fig. 3 and 11, includes a horizontal interference plate 251 and a vertical interference plate 252. The horizontal interference preventing plates 251 are, as shown in fig. 3 and 11, arranged horizontally along the horizontal direction, and uniformly distributed at equal intervals along the longitudinal direction, and the horizontal interference preventing plates 251 are perpendicular to the horizontal direction, which can be understood as that the horizontal interference preventing plates 251 are arranged along the vertical direction; the vertical interference preventing plates 252 are, as shown in fig. 12, arranged in the horizontal direction, distributed in the longitudinal direction, and uniformly distributed in the transverse direction at equal intervals, and the vertical interference preventing plates 252 are perpendicular to the horizontal direction, which can be understood as that the vertical interference preventing plates 252 are arranged in the vertical direction. The transverse interference plate 251 and the longitudinal interference plate 252 penetrate through each other and are fixed to form a grid in a shape like a Chinese character 'jing', and the transverse interference plate 251 and the longitudinal interference plate 252 are suitable for guiding carrier gas which passes through the mesh holes of the baking belt 21 and flows downwards, flow towards the gas trapping head 24, flow into the gas trapping holes 242, are trapped by the gas trapping head 24 and are sucked and exhausted by a vacuum pump through an exhaust pipeline. The adoption of the interference preventing grille 25 can avoid that when the air trapping head 24 sucks and traps the carrier gas, especially when the vacuum degree is low, such as when the air pressure in the baking chamber in the initial stage of vacuum pumping is high, the flow rate of the sucked and exhausted air is large and the air flow rate is high, the flow resistance of each air trapping hole 242 is different, so that the flow path of the carrier gas is excessively bent, even turbulence is generated, the uniformity of the distribution of the carrier gas air flow is damaged, the uniform distribution of the carrier gas air flow between the air distributing head 22 and the baking belt 21 is disturbed, the uniformity of the distribution of the air flow is damaged, even turbulence is generated in the air flow flowing out from the air nozzle 223, the uniform air drying of the food is influenced, and the uniformity (namely, consistency) of the food quality is reduced. The arrangement of the interference barrier 25 can further improve the uniformity of the carrier gas flow among the gas distribution head 22, the baking belt 21 and the gas trapping head 24, so that the consistency of the quality of the baked food in the vacuum environment with the carrier gas is better, for example, the crispness uniformity and the color uniformity are better, the taste is improved, and the problems that some foods are too hard, some foods are too crisp, some foods are under-colored and some foods are over-colored are effectively avoided, and the yield of the food is improved. In order to prevent the disturbance of the airflow captured by the gas-capturing head 24 by the oven chamber wall of the roaster 20 from affecting the uniform distribution of the airflow, the flow restricting plates 253 are provided on the peripheral sides of the interference grill 25, and as shown in fig. 3 and 12, the flow restricting plates 253 are each formed in a strip-shaped plate shape and are provided in the vertical direction, and the upper ends of the flow restricting plates 253 are inclined outward (with respect to the center portion of the interference grill 25) with respect to the lower ends. The four flow restriction plates 253 are connected end to end in sequence to form an inverted apron-shaped structure, as shown in fig. 3 and 12, the upper end opening of the apron-shaped structure formed by the flow restriction plates 253 is larger than the lower end opening thereof, which is beneficial for the carrier gas to be exhausted to flow into the gas trapping head 24 for exhaust. Based on a large number of experimental comparisons, it is found that when the upper end side of the flow restriction plate 253 is inclined outward by 20 to 26 degrees, particularly 22 to 24 degrees, relative to the vertical direction, the disturbance influence of the oven wall of the baking device 20 on the uniform distribution of the carrier gas flow is minimal, no obvious turbulence is formed at the peripheral side of the gas capture head 24, the uniformity of the carrier gas flow in the region is better, accordingly, the influence of the suction capture gas of the gas capture head 24 on the gas distribution head 22 is further reduced, and the uniformity of the distribution of the carrier gas flow discharged by the gas distribution head 22 is further effectively improved.

In order to further improve the uniform distribution of the carrier gas flow between the cold wind shower head 32 and the air trapping bin 33, to uniformly cool and dry the food, and to ensure the consistency of quality, particularly the crispness and uniformity, the flow equalizing grid described above may be provided between the cold wind shower head 32 and the cold carrying strip 31, and the interference preventing grid described above may be provided between the cold carrying strip 31 and the air trapping bin 33.

Examples

The walnut cake examples show 2 batches of baked walnut cakes, the raw material proportion and the manufacturing process of the 2 batches of the walnut cakes are the same, no preservative is added, and the food vacuum baking equipment is adopted for baking and cooling. Baking the 1 st batch of walnut cakes in an air environment, cooling, sealing and vacuum-packaging in the air environment, randomly selecting 10 walnut cake samples from the baked walnut cakes for testing, wherein 5 walnut cake samples are reserved for a storage period test, and the other 5 walnut cake samples are reserved for a grease oxidation deterioration matter and a hardness test; the 2 nd batch of walnut cakes are baked and cooled in a vacuum environment with carrier gas, sealed and vacuum-packed in an air environment, and 10 walnut cake samples are randomly selected from the baked walnut cakes to be tested, wherein 5 walnut cake samples are tested for the storage period, and the other 5 walnut cake samples are tested for the oxidation deterioration of oil and fat and the hardness. The content of oxidative deterioration of the grease and the hardness of the sample are tested, and the test conditions are shown in the table I; the test conditions relating to the storage period of the samples are shown in Table II below. Wherein, for the requirement of data processing, the oxidation metamorphic substance and the hardness of the grease are respectively normalized.

Table one: oil oxidation deterioration and hardness test conditions of walnut cake sample

Note: the content of the oil oxidation deterioration substances in the walnut cakes is normalized based on the No. 11-1 sample, and the peaches

The hardness of the cake was normalized based on sample #11-1

The data in the table I show that the oxidation degree of the oil in the walnut cake sample baked in the air environment is large, the content of the oil oxidation deterioration matter in the sample is high, the oxidation degree of the oil in the walnut cake sample baked in the vacuum environment with the carrier gas is obviously reduced, and the content of the oil oxidation deterioration matter in the sample is very low, so that compared with the walnut cake sample baked in the air environment, the content of the oil oxidation deterioration matter in the walnut cake sample baked in the vacuum environment with the carrier gas is reduced by more than 90 percent and is less than 10 percent of that in the walnut cake sample baked in the air environment, therefore, the oxygen absorption capacity of the walnut cake is greatly reduced, the walnut cake is more beneficial to the storage of the walnut cake, and the shelf life of the walnut cake is longer; on the other hand, the content of the oxidative deterioration matters of the grease is reduced, so that the health is facilitated.

The data in table one also shows that the hardness of the walnut cake samples baked in an air environment is greater, while the hardness of the walnut cake samples baked in a vacuum environment with a carrier gas is significantly reduced, and the hardness of the walnut cake samples baked in a vacuum environment is less than 85% of that baked in an air environment, and the crunchiness of the walnut cake samples is significantly improved as compared to the walnut cake samples baked in an air environment. It is demonstrated that the vacuum boiling puffing treatment before vacuum baking can effectively improve the crispness of the food.

Table two: testing of shelf life of walnut cake samples

The data in table two show that 5 walnut cake samples prepared by baking and cooling in an air environment and vacuum-packaging in an air environment have shelf lives of 84-112 days and an average shelf life of 92.8 days; baking the prepared 5 walnut cake samples in a vacuum environment with nitrogen carrier gas, and vacuum-packaging in an air environment, wherein the shelf life of the 5 walnut cake samples is 168-208 days, and the average shelf life is 186.6 days. Namely, the shelf life of the walnut cakes baked in the vacuum environment with nitrogen carrier gas is prolonged to more than 2 times of the original shelf life, namely the shelf life is prolonged by more than 1 time, and the shelf life is obviously prolonged.

The biscuit shows baked biscuits of 2 batches in total, the raw material proportion and the making process of each batch of biscuits are the same, no preservative is added, and the food vacuum baking equipment is adopted for baking and cooling. Baking the 1 st batch of biscuits in an air environment, cooling, sealing and vacuum packaging in the air environment, randomly selecting 10 biscuit samples from the baked biscuits, wherein 5 biscuit samples are reserved for a storage period test, and the other 5 biscuit samples are used for a grease oxidation deterioration matter and a hardness test; biscuit batch 2 was baked and cooled in a vacuum environment with nitrogen carrier gas and hermetically vacuum packed in an air environment, and 10 biscuit samples were randomly selected from the baked biscuits, of which 5 were left for shelf life testing and 5 were tested for fat oxidation deterioration and hardness. The test conditions of the content and the hardness of the oxidative deterioration substances of the sample oil are shown in the third table; the test conditions concerning the storage period of the samples are shown in table four below. Wherein, for the data processing requirement, the oxidation metamorphic substance and the hardness of the grease are respectively normalized.

Table three: oil oxidation deterioration content and hardness test condition of biscuit sample

Note: the content of the oil oxidation deterioration substances in the biscuit is normalized based on a No. 31-1 sample, and the biscuit

Dry hardness was normalized based on sample #31-1

The data in table three show that the oxidation degree of grease in the biscuit sample baked in the air environment is large, the content of grease oxidation deterioration substances in the sample is high, the oxidation degree of grease in the biscuit sample baked in the vacuum environment with carrier gas is obviously reduced, the content of grease oxidation deterioration substances in the sample is very low, compared with the biscuit sample baked in the air environment, the content of grease oxidation deterioration substances in the biscuit sample baked in the vacuum environment with carrier gas is reduced by more than 90 percent and is less than 10 percent of that of the biscuit sample baked in the air environment, so that the oxygen absorption capacity of the biscuit is greatly reduced, the biscuit is more favorably stored, and the quality guarantee period of the biscuit is longer; on the other hand, the reduction of the oxidation deterioration content of the grease is beneficial to health.

The data in table three also show that the hardness of the cookie samples baked in an air environment is greater, while the hardness of the cookie samples baked in a vacuum environment with a carrier gas is significantly reduced, and the hardness of the cookie samples baked in a vacuum environment is less than 85% of that baked in an air environment, and the crispness of the cookie samples is significantly improved compared to the cookie samples baked in an air environment. It is also demonstrated that the vacuum boiling puffing treatment before vacuum baking can effectively improve the crispness of the food.

Table four: testing of shelf-life of biscuit samples

The data in table four show that 5 prepared biscuit samples were baked and cooled in an air environment and vacuum packed in an air environment, the 5 biscuit samples had shelf lives of 86-109 days with an average shelf life of 94.0 days; the 5 prepared biscuit samples were baked in a vacuum environment with nitrogen carrier gas and vacuum-packed in an air environment, the 5 biscuit samples had a shelf life of 172-. Namely, the shelf life of the baked biscuit in the vacuum environment with nitrogen carrier gas is improved to more than 2 times of the original shelf life, namely the shelf life is improved by more than 1 time, and the shelf life is obviously improved.

The technical parameters of the food baked by the food vacuum baking equipment are explained by taking walnut cakes and biscuits as examples, and in addition, the food vacuum baking equipment is also suitable for baking dry and crisp foods such as baked cakes, wife cakes, dried purple potatoes, potato chips and the like. Before baking, the food to be baked is subjected to vacuum boiling puffing treatment, the moisture in the food is boiled and gasified in vacuum, the food is boiled and puffed, and the crispness of the food is improved. The baking and cooling of the food are both carried out in a vacuum environment with carrier gas, the carrier gas timely discharges baking volatile matters such as oil volatilized during baking the food and trace metal ion gas volatilized at high temperature in a baking chamber, the food is isolated from air, the oil in the food is difficult to oxidize and the metal is catalyzed and oxidized to generate oil oxidation metamorphic substances which are harmful to health, the oxygen absorption capacity of the food is reduced, the oxygen residual quantity in the food is lower, and the shelf life of the food is prolonged.

The food in the prior art is baked in an air environment, and a large amount of grease and puffing agent are required to be added to improve the crispness of the food, so that the hardening rate of the food is reduced, and the crispness of the food is improved. The baking temperature is as high as 190 ℃, even higher, the grease in the food directly contacts the air, and trace metal ion gas volatilized at high temperature in the baking chamber, such as metal ion gas of Fe, Cu, Mn, Cr and the like, catalyzes the grease to generate oxidation reaction. The oil is oxidized at high temperature and subjected to hydrogen peroxide reaction catalyzed by metal to generate oxidation metamorphic substances, the oxidation metamorphic substances promote the high-temperature oxidation of the oil, the oxidation speed of the oil is accelerated, more oil oxidation metamorphic substances harmful to health are generated, the oxygen capturing capability of the food is improved, the food is easy to oxidize, rancid and deteriorate during storage, the shelf life is short, and the using amount of a preservative is required to be increased in order to improve the shelf life.

Before baking, the food to be baked is subjected to vacuum boiling puffing pretreatment, in a high vacuum environment, if the pressure is less than 50 Pa, moisture in the food is boiled and gasified, air holes are formed in the food to expand, the food is subjected to vacuum boiling puffing, the puffing rate is improved, the crispness and the crispness uniformity of the baked food are further improved, and the hardness of the food can be reduced by more than 15%.

The baking of the food is finished in the baking device, and the cooling of the food is finished in the cooling device, so that the method is suitable for continuous production, is favorable for improving the productivity and reducing the energy consumption of unit products.

The foregoing shows and describes the general principles, essential features, and advantages of the invention.

Claims

1. A food vacuum grilling apparatus for advantageously improving the crispness of a food item, comprising:

2. A food vacuum grilling apparatus as claimed in claim 1, wherein: the gas distribution head comprises a shunt pipe suitable for shunting the input carrier gas, and a plurality of parallel flow guide pipes arranged along the horizontal plane direction, wherein the shunt pipe is provided with an input port suitable for inputting the carrier gas and a plurality of output ports communicated with the input port and suitable for shunting the carrier gas; the output port of the shunt pipe and the input ports of the diversion pipes are respectively in sealed circulation, and a plurality of air nozzles positioned on the lower end face of the diversion pipes are arranged on the diversion pipes, are opposite to the baking support belt and are suitable for shunting, guiding and flowing the carrier gas in the diversion pipes to the baking support belt.

3. A food vacuum grilling apparatus as claimed in claim 2, wherein: the baking device also comprises a flow equalizing grid which is arranged between the gas distributing head and the baking support belt and close to one side of the gas distributing head, and is suitable for the uniform distribution of carrier gas flow between the gas distributing head and the baking support belt; the flow equalizing grid at least comprises transverse flow equalizing plates which are distributed at equal intervals along the longitudinal direction and longitudinal flow equalizing plates which are distributed at equal intervals along the transverse direction; the transverse flow equalizing plate and the longitudinal flow equalizing plate are arranged in the vertical direction and penetrate through each other to form a grid shape.

4. A food vacuum grilling apparatus as claimed in claim 3, wherein: the four sides of the flow equalizing grid are respectively provided with a flow baffle plate in a strip shape, the flow baffle plate is arranged along the vertical direction, and the lower end of the flow baffle plate inclines outwards relative to the upper end; the spoilers around the flow equalization grid are sequentially connected end to form an apron-shaped structure with a lower end opening larger than an upper end opening.

5. A food vacuum grilling apparatus as claimed in claim 1, wherein: the gas trapping head is of a shell-shaped structure, a plurality of annular gas trapping holes suitable for carrier gas to flow in are formed in the top end face of the gas trapping head, a flow guide cavity horizontally arranged along the horizontal plane is formed in the gas trapping head, and an exhaust port suitable for being connected with an exhaust pipeline is formed in the bottom end face of the gas trapping head.

6. A food vacuum grilling apparatus as claimed in claim 5, wherein: the baking device also comprises a disturbance-resisting grating which is arranged between the baking belt and the gas trapping head and close to one side of the baking belt and is suitable for the uniform distribution of carrier gas flow between the baking belt and the gas trapping head; the interference prevention grating at least comprises transverse interference prevention plates which are distributed at equal intervals along the longitudinal direction and longitudinal interference prevention plates which are distributed at equal intervals along the transverse direction; the transverse interference resisting plates and the longitudinal interference resisting plates are arranged in the vertical direction and penetrate through each other to form a grid shape.

7. A food vacuum grilling apparatus as claimed in claim 6, wherein: the sides of the periphery of the interference prevention grating are respectively provided with a strip-shaped current limiting plate which is arranged along the vertical direction, and the upper end of the current limiting plate inclines outwards relative to the lower end; the flow limiting plates around the interference-resisting grating are sequentially connected end to form an inverted apron-shaped structure with an upper end opening larger than a lower end opening.

8. A food vacuum grilling apparatus as claimed in claim 6, wherein: the cold air sprinkling head is of a plate-shaped shell structure, an input port suitable for carrier gas input is arranged in the middle of the top end face of the cold air sprinkling head, a cold air cavity arranged in the horizontal direction is arranged in the cold air sprinkling head, and a plurality of cold air nozzles opposite to the cold supporting belt are arranged on the bottom end face of the cold air sprinkling head.

9. A food vacuum grilling apparatus as claimed in claim 7, wherein: the exhaust trapping bucket is of a funnel-shaped structure formed by surrounding of side walls, an opening in the top end of the exhaust trapping bucket is suitable for carrier gas to flow in, an output port suitable for carrier gas to flow out is arranged at the lower end of the exhaust trapping bucket, the output port is communicated with one end of an exhaust pipeline of the cooling device, the other end of the exhaust pipeline is communicated with an input port of the heat exchanger, and the 4 th valve is assembled on the input port side of the heat exchanger.

10. A food vacuum grilling apparatus as claimed in claims 1-9, wherein: the gas supply device comprises a gas storage tank, a gasifier, a temporary storage tank and a pressure reducing valve, wherein the gas storage tank is suitable for storing liquid carrier gas, the gasifier is suitable for gasifying the liquid carrier gas to generate gaseous carrier gas, the temporary storage tank is suitable for storing the gaseous carrier gas generated by the gasifier, and the pressure reducing valve is suitable for reducing the output pressure of the carrier gas and stabilizing the pressure.