CN111528271A

CN111528271A - Sweet potato storage pretreatment equipment and pretreatment method

Info

Publication number: CN111528271A
Application number: CN202010464047.9A
Authority: CN
Inventors: 刘帮迪; 冉国伟; 孙洁; 吕晓龙; 沈剑波; 孙静; 程勤阳; 周新群
Original assignee: Academy of Agricultural Planning and Engineering MARA
Current assignee: Academy of Agricultural Planning and Engineering MARA
Priority date: 2020-05-27
Filing date: 2020-05-27
Publication date: 2020-08-14

Abstract

The invention relates to the technical field of sweet potato storage, and discloses sweet potato storage pretreatment equipment and a pretreatment method, wherein the sweet potato storage pretreatment equipment comprises a callus chamber and a cooling chamber, wherein the callus chamber and the cooling chamber are oppositely arranged by an access door; and one end of the cooling chamber, which deviates from the callus chamber, is connected with a second air supply fan. The sweet potato storage pretreatment equipment can effectively accelerate the formation of the callus of the tuberous roots of the sweet potatoes and shorten the pretreatment time by carrying out high-temperature short-time callus-cooling pretreatment on the sweet potatoes before postnatal storage by a green pollution-free physical method, thereby achieving the purposes of reducing the rot and water loss of the sweet potatoes in the storage period, ensuring the storage quality and prolonging the storage period.

Description

Sweet potato storage pretreatment equipment and pretreatment method

Technical Field

The invention relates to the technical field of sweet potato storage, in particular to a sweet potato storage pretreatment device and a sweet potato storage pretreatment method.

Background

The sweet potato tuber has large volume, much water content, thin skin and tender meat, and is easily damaged by machines such as scratch, puncture, cut, bruise, pressure injury and the like in the processes of field harvesting, transportation, loading, unloading, warehousing and storage. In order to reduce the loss of the picked sweet potatoes and prevent the invasion of pathogens, the picked sweet potatoes are subjected to proper pretreatment, washed to remove soil-borne microorganisms on the surface, and stored after injury healing is promoted, so that the disease resistance of the sweet potatoes is improved, the storage period is prolonged, and the storage quality is ensured. The pretreatment methods adopted in the current production practice mainly comprise three methods, namely callus pretreatment, cleaning pretreatment and chemical agent pretreatment.

The callus pretreatment is mainly a traditional low-temperature heating callus pretreatment technology, sweet potatoes are usually selected and directly stacked in a storage facility for carrying out callus pretreatment, the temperature of the sweet potatoes is raised to 30-37 ℃ after the sweet potatoes are put in a warehouse, the treatment time is usually 2-7 days, and then the sweet potatoes are ventilated and cooled to enter a storage period. At present, no special equipment for callus pretreatment of sweet potatoes exists in the market and research, and the traditional low-temperature heating callus is usually carried out in a heating cold storage or a soil cellar.

The pretreatment of the chemical agent mainly comprises spraying the chemical agent to stimulate the callus, wherein the chemical agent treatment is generally that before storage, exogenous hormones such as Abscisic Acid (ABA), Benzothiadiazole (BTH) and Salicylic Acid (SA) are sprayed and soaked, and then the dried sweet potatoes are put in storage for storage, and the mode is mainly that the stimulation of the exogenous chemical agent is carried out on the sweet potatoes to promote the wound self-healing of the sweet potatoes in the storage process.

The cleaning pretreatment mainly comprises clear water cleaning or chemical agent cleaning, and mainly comprises the steps of cleaning the soil on the surface of the sweet potato by using clear water flushing cleaning, sodium hypochlorite solution flushing cleaning, lime spraying, pesticide soaking or spraying, bactericide flushing cleaning and the like, inactivating soil-borne microorganisms, draining, and warehousing for storage.

At present, the three main pretreatment methods all have some use defects, so that the storage effect of the sweet potatoes is poor. The low-temperature heating callus pretreatment period is long, the input of manpower and material resources is large, the conditions are difficult to control, the energy consumption is high, the callus effect is uneven, the cooling effect is not obvious, the final residual temperature of the sweet potatoes cannot be dissipated, the sweet potatoes are easy to rot in the storage period, and the production requirement cannot be met. The cleaning pretreatment and the chemical agent pretreatment relate to the problems of food safety and irregular use amount of chemical agents, the cost of exogenous hormone medicines is high, the sweet potato surface is wet easily due to spraying, soaking and other modes, the draining time is short, and the rotting in the storage period can be accelerated.

Disclosure of Invention

The embodiment of the invention provides a sweet potato storage pretreatment device and a pretreatment method, which are used for solving the problems that the existing sweet potato pretreatment has long treatment period and poor effect and cannot meet the production requirement.

The embodiment of the invention provides a sweet potato storage pretreatment device which comprises a callus chamber and a cooling chamber, wherein the callus chamber and the cooling chamber are oppositely arranged at an inlet and an outlet, one end of the callus chamber, which is far away from the cooling chamber, is connected with a first air supply fan, and a heating device is arranged between an outlet of the first air supply fan and the callus chamber; and one end of the cooling chamber, which deviates from the callus chamber, is connected with a second air supply fan.

The embodiment of the invention also provides a pretreatment method by using the sweet potato storage pretreatment equipment, which comprises the following steps:

cleaning the sweet potatoes after being bagged;

conveying the cleaned sweet potato basket filled with the sweet potatoes into a callus chamber, wherein the temperature in the callus chamber is 60-65 ℃, the relative humidity is 20-30%, and the wind speed is at least 0.5m/s, and performing callus treatment for 20-40 min;

transferring the sweet potatoes after the callus treatment into a cooling chamber, wherein the temperature of the cooling chamber is 15-20 ℃, the relative humidity is 20-30%, and the wind speed is at least 0.5m/s, and carrying out cooling treatment;

and taking out the sweet potatoes for storage after the temperature of the sweet potatoes is reduced to below 18 ℃.

The sweet potato storage pretreatment equipment and the pretreatment method provided by the embodiment of the invention have the advantages that the sweet potato storage pretreatment equipment carries out high-temperature short-time callus treatment on the sweet potatoes through the callus chamber, the injured pericarp of the sweet potatoes is quickly healed by utilizing a mode of thermally stimulating and regulating metabolic pathways and killing epidermal microorganisms at high temperature to form a biological barrier for resisting external disease microorganisms, the sweet potatoes after callus are quickly cooled by strong wind through the cooling chamber, the residual temperature of the sweet potatoes after callus is quickly reduced, the increase and loss of respiratory strength in the storage process are avoided, and the rotting condition in the early stage of storage is reduced. The sweet potato storage pretreatment equipment can effectively accelerate the formation of the callus of the tuberous roots of the sweet potatoes and shorten the pretreatment time by carrying out high-temperature short-time callus-cooling pretreatment on the sweet potatoes before postnatal storage by a green pollution-free physical method, thereby achieving the purposes of reducing the rot and water loss of the sweet potatoes in the storage period, ensuring the storage quality and prolonging the storage period.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a schematic view showing the construction of a sweet potato storage pretreatment apparatus according to an embodiment of the present invention;

FIG. 2 is a plan view of the sweet potato storage pretreatment apparatus of FIG. 1;

FIG. 3 is a flow chart of a pretreatment process before sweet potato storage in the embodiment of the present invention;

FIG. 4 is a schematic view showing stacking of sweet potatoes in the same batch using a sweet potato storage pretreatment apparatus in an embodiment of the present invention, wherein a represents an upper sweet potato sample point, b represents a middle sweet potato sample point, and c represents a lower sweet potato sample point;

FIG. 5 is a graph showing the results of temperature monitoring changes of the temperature sensors in the callus chamber of the present invention;

FIG. 6 is a graph showing the results of humidity monitoring changes of humidity sensors in the callus chamber of the present invention;

FIG. 7 is a graph showing the temperature measurement results of the epidermis and the kernel of the same batch of sweet potatoes at different placing points after the callus treatment of the present invention;

FIG. 8 is a graph showing the temperature measurements of the outer skin and inner core of sweet potatoes in the same batch at different placement points after cooling treatment according to the present invention;

FIG. 9 is a graph of the results of the L value test after storage of example 1 and comparative examples 1 to 4;

FIG. 10 is a graph of the results of the a value test after storage of example 1 and comparative examples 1-4;

FIG. 11 is a graph of b-value test results of example 1 and comparative examples 1-4 after storage;

FIG. 12 is a graph showing the results of the browning test of sweet potatoes in example 1 and comparative examples 1 to 4 after storage;

FIG. 13 is a graph showing the results of the measurement of the respiration intensity of sweet potatoes in example 1 and comparative examples 1 to 4 after storage;

FIG. 14 is a graph showing the results of the internal hardness test of the sweet potato tissues after storage in example 1 and comparative examples 1 to 4;

FIG. 15 is a graph showing the results of the hardness test of the head and tail parts of sweet potatoes stored in example 1 and comparative examples 1 to 4;

FIG. 16 is a graph showing the results of the cell membrane permeability test of sweet potatoes stored in example 1 and comparative examples 1 to 4;

FIG. 17 is a graph showing the results of the malondialdehyde content test of sweet potatoes in example 1 and comparative examples 1 to 4 after storage;

FIG. 18 is a graph showing the results of a test of the incidence of cold damage of sweet potatoes stored in example 1 and comparative examples 1 to 4;

FIG. 19 is a graph showing the results of a test of rotting rate of sweet potatoes in example 1 and comparative examples 1 to 4 after storage;

FIG. 20 is a graph showing the results of weight loss rate tests of sweet potatoes in example 1 and comparative examples 1 to 4 after storage;

FIG. 21 is a graph showing the results of the starch content test of sweet potatoes in example 1 and comparative examples 1 to 4 after storage;

FIG. 22 is a graph showing the results of the soluble sugar content test of sweet potatoes in example 1 and comparative examples 1 to 4 after storage;

FIG. 23 is a graph showing the results of the ascorbic acid content test of sweet potatoes stored in example 1 and comparative examples 1 to 4.

Description of reference numerals:

1. a callus chamber; 2. A cooling chamber; 3. A first air supply fan;

4. a second air supply fan; 5. A main blast pipe; 6. A heating device;

7. an air return duct; 8. A lower air supply duct; 9. A top window;

10. a three-way regulating valve; 11. A front end temperature and humidity sensor; 12. A terminal temperature and humidity sensor;

13. an electric air inlet valve; 14. A moisture removal fan; 15. A slide rail;

16. sweet potato baskets; 17. An air outlet valve of the callus chamber; 18. An air outlet of the cooling chamber;

19. a wind scoop; 20. A cleaning chamber; 21. A shower head;

22. a water outlet; 23. A control box; 24. And (5) wet curtain.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. 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 invention.

In the description of the embodiments of the present invention, it should be noted that the terms "first" and "second" are used for clearly indicating the numbering of the product parts and do not represent any substantial difference unless explicitly stated or limited otherwise. The terms "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly. Specific meanings of the above terms in the embodiments of the present invention can be understood by those of ordinary skill in the art according to specific situations.

It is to be understood that, unless otherwise expressly specified or limited, the term "coupled" is used broadly, and may, for example, refer to directly coupled devices or indirectly coupled devices through intervening media. Specific meanings of the above terms in the embodiments of the invention will be understood to those of ordinary skill in the art in specific cases.

As shown in figures 1 to 2, the sweet potato storage pretreatment equipment provided by the embodiment of the invention comprises a callus chamber 1 and a cooling chamber 2 which are oppositely arranged at an access door, wherein one end of the callus chamber 1, which is far away from the cooling chamber 2, is connected with a first air supply fan 3, and a heating device 6 is arranged between the outlet of the first air supply fan 3 and the callus chamber 1. One end of the cooling chamber 2 departing from the callus chamber 1 is connected with a second air supply fan 4.

Specifically, callus on the sole room 1 and the relative setting of cooling chamber 2, callus on the sole room 1 and cooling chamber 2 all can be an open-ended cavity box in both ends, and the size of box can be as required rational design. In a specific embodiment, the callus chamber 1 and the cooling chamber 2 have a volume of 12m³700 kg-800 kg of sweet potatoes can be processed at one time.

One end of the callus chamber 1 departing from the cooling chamber 2 is connected with the outlet of the first air supply fan 3 through an air hopper 19, a heating device 6 and a main air supply pipe 5 in sequence; one end of the callus chamber 1 facing the cooling chamber 2 is provided with a first opening and closing door. After the first access door is opened, the sweet potatoes to be treated can be put into the callus chamber 1, and the sweet potatoes after the callus treatment can also be moved out of the callus chamber 1. In addition, a callus chamber air outlet valve 17 can be further installed on the first access door, and the callus chamber air outlet valve 17 can be a manual air valve or an electric air valve. By opening the first air supply fan 3 and the air outlet valve 17 of the callus chamber (or directly opening the first access door), a tunnel type ventilation mode can be formed in the callus chamber 1. The first air supply fan 3 can adopt a centrifugal fan, and a frequency converter can be additionally arranged as required to adjust the air speed in the callus chamber 1. The heating device 6 may employ an electric heater, and more specifically, the electric heater may employ a PTC thermistor material as a heating element, while having an enhanced overload protection function.

One end of the cooling chamber 2, which is far away from the callus chamber 1, is connected to the outlet of the second air supply fan 4 through an air hopper 19 and an air supply pipe in sequence; the cooling chamber 2 is provided with a second openable and closable access door at one end facing the callus chamber 1. After the second access door is opened, the sweet potatoes after the callus treatment can be placed into the cooling chamber 2, and the sweet potatoes after the cooling treatment can also be moved out of the cooling chamber 2 and finally placed into a storage cellar or a cold storage for storage. In addition, a cooling chamber air outlet 18 can be further installed on the second access door, and the cooling chamber air outlet 18 can be a shutter air outlet or other air outlet structures. By opening the second air supply fan 4 and the cooling compartment air outlet 18 (or directly opening the second access door), a tunnel type ventilation mode can be formed in the cooling compartment 2. The second air supply fan 4 can adopt a centrifugal fan, and a frequency converter can be additionally arranged as required to adjust the air speed in the cooling chamber 2.

When the device is used, sweet potatoes can be firstly centralized and bagged in the area between the callus chamber 1 and the cooling chamber 2, the stacked sweet potatoes are orderly transferred to the callus chamber 1 to be callus, after the callus treatment is finished, the whole sweet potatoes are directly transferred from the callus chamber 1 to the cooling chamber 2 to be cooled, and the sweet potatoes can be unloaded from the area between the callus chamber 1 and the cooling chamber 2 after the cooling treatment is finished. In addition, the callus chamber 1 and the cooling chamber 2 can be continuously used at the same time, when the sweet potatoes in the previous batch are processed in the cooling chamber 2, the sweet potatoes in the next batch can be transferred into the callus chamber 1 for callus processing, and the overall processing speed is further improved.

The embodiment provides a sweet potato storage pre treatment equipment, carry out high temperature short-time callus on the earth through callus on the earth room 1 to the sweet potato, utilize the heat shock to adjust metabolic pathway and the mode of high temperature extermination epidermis microorganism, make the injured pericarp of sweet potato heal fast, form the biological barrier who resists outside disease microorganism, the rethread cooling chamber 2 carries out strong wind fast cooling to the sweet potato after healing, reduce the residual temperature of sweet potato after healing fast, avoid promotion and the loss of respiratory intensity among the storage process, reduce the rotten condition of early stage of storage. The sweet potato storage pretreatment equipment can effectively accelerate the formation of the callus of the tuberous roots of the sweet potatoes and shorten the pretreatment time by carrying out high-temperature short-time callus-cooling pretreatment on the sweet potatoes before postnatal storage by a green pollution-free physical method, thereby achieving the purposes of reducing the rot and water loss of the sweet potatoes in the storage period, ensuring the storage quality and prolonging the storage period.

Further, as shown in fig. 1 and fig. 2, it also includes a slide rail 15 and a loading trolley (not shown in the figure), one end of the slide rail 15 extends into the callus chamber 1, and the other end of the slide rail 15 extends into the cooling chamber 2. The loading trolley can slide along the slide rails 15. In particular, the loading trolley can be an electric flat car or a trolley, and the sweet potatoes can be easily and effortlessly translated between the callus chamber 1 and the cooling chamber 2 through the loading trolley. The loading trolley can be loaded with a plurality of sweet potato baskets 16 made of plastic materials.

Furthermore, as shown in fig. 1, a return air duct 7 is arranged above the callus chamber 1, an inlet of the return air duct 7 is communicated with an inner chamber of the callus chamber 1, and an outlet of the return air duct 7 is connected to an inlet of the first air supply fan 3. A lower air supply duct 8 is arranged below the callus chamber 1, the inlet of the lower air supply duct 8 is connected with the outlet of the heating device 6, and the outlet of the lower air supply duct 8 is communicated with the inner chamber of the callus chamber 1. Through the arrangement of the lower air supply duct 8 and the air return duct 7, hot air can pass through the inner cavity of the callus chamber 1 from bottom to top, and a box type ventilation mode is formed.

Furthermore, as shown in fig. 1 and 2, the top of the callus chamber 1 is provided with a plurality of openable top windows 9 in the length direction, and the inlet of the return air duct 7 is communicated with the inner chamber of the callus chamber 1 through the top windows 9. The top window 9 can adopt a manual push window or an electric push window. The return air duct 7 may be provided with a plurality of inlets, each inlet being provided in one-to-one correspondence with the roof window 9. The lower air supply duct 8 can also be provided with a plurality of outlets along the length direction of the callus chamber 1, so that uniform air outlet is ensured.

Furthermore, as shown in FIG. 1, the outlet of the heating device 6 is connected to the inlet of the lower air supply duct 8 and the air inlet of the callus chamber 1 through a three-way regulating valve 10. Specifically, the valve body of three-way regulating valve 10 can be directly with 19 integrated designs of wind scoop, lower air supply duct 8 locate in 19 wind scoop and form the junction at 19 neck of wind scoop, three-way regulating valve 10 still sets up the valve plate at the junction including rotating, and the pivot of valve plate can extend to 19 outer formation handles of wind scoop, also can lug connection in the motor, realizes automatically controlled.

The inlet of the lower air supply duct 8 can be completely shielded by rotating the valve plate, and at the moment, the air outlet of the first air supply fan 3 completely enters the inner chamber from the air inlet of the callus chamber 1 to form tunnel type ventilation; or the valve plate completely shields the air inlet of the callus chamber 1, at the moment, the air outlet of the first air supply fan 3 completely enters the inner chamber from the lower air supply duct 8, and the top window 9 can also be opened in a linkage manner (or manually opened independently) with the three-way regulating valve 10, so that box type ventilation is formed; or the valve plate can be kept at the middle position, so that the outlet air can enter the inner chamber of the callus chamber 1 from the air inlet of the callus chamber 1 and the lower air supply duct 8 at the same time, and tunnel type and box type synchronous ventilation is formed. Generally, when the sweet potato treatment capacity is small, the sweet potato can be independently put into a tunnel type for ventilation; when the sweet potato treatment capacity is large, the sweet potato can be independently put into a box type for ventilation, hot air can be recycled through the box type ventilation, the improvement of the heat utilization rate is facilitated, and energy is saved.

Further, as shown in fig. 1 and 2, the device also comprises a cleaning chamber 20 arranged between the callus chamber 1 and the cooling chamber 2, and a plurality of spray heads 21 are arranged in the cleaning chamber 20. The sweet potatoes loaded in the sweet potato basket 16 can be washed by clean water through the spray header 21, so that large soil on the surfaces of all the sweet potatoes can be washed. The bottom of the washing chamber 20 is further provided with a water outlet 22, and the sewage accumulated in the washing chamber 20 is discharged in time through the water outlet 22, so that the sewage can be collected and treated in a centralized manner.

Further, as shown in fig. 1, a temperature sensor and a humidity sensor are installed in the callus chamber 1, and an electric air inlet valve 13 and a moisture exhaust fan 14 connected with a control box 23 are also installed in the callus chamber 1. Specifically, the front, middle and end, upper and lower, and left and right sides of the callus chamber 1 may be provided with temperature sensors and humidity sensors as needed. In a specific embodiment, the front section of the callus chamber 1 is provided with a front end temperature and humidity sensor 11, and the tail section is provided with a tail end temperature and humidity sensor 12. The temperature sensor, the humidity sensor, the first air supply fan 3, the heating device 6, the electric air inlet valve 13 and the dehumidifying fan 14 are all electrically connected with a control box 23 arranged outside the callus chamber 1. When the humidity of the callus chamber 1 is higher than the set humidity, the humidity sensor collects data to the control box 23, the control box 23 sends an instruction to open the electric air inlet valve 13 and the dehumidifying fan 14 after judging, external air enters the callus chamber through the electric air inlet valve 13, and indoor humid air is discharged out of the callus chamber 1 through the dehumidifying fan 14; when the humidity of the callus chamber 1 is lower than or equal to the set humidity, the electric air inlet valve 13 and the moisture exhaust fan 14 are stopped. The temperature and the humidity in the callus chamber 1 are controlled to be kept suitable by a temperature sensor and a humidity sensor. Further, as shown in fig. 1, a wet curtain 24 is installed between the outlet of the second blower fan 4 and the cooling compartment 2. In particular, the wet curtain 24 may be mounted within the wind scoop 19. The wet curtain 24 can provide cold for the cooling chamber 2, and when the air supply of the second air supply fan 4 passes through the wet curtain 24, a large amount of moisture is evaporated, so that the air supply temperature is reduced, and then the air supply temperature enters the cooling chamber 2, so that the indoor temperature is rapidly reduced. The sweet potatoes are generally harvested and stored in autumn in the north, the environmental temperature is lower at the moment and is about 15-20 ℃, and the sweet potatoes are cooled by wind at the environmental temperature. If the device is to be put into use in the south or summer, it is contemplated that the wet curtain 24 may be added or put into use.

Furthermore, the outside of the callus chamber 1 and the cooling chamber 2 is provided with a heat preservation layer, and the heat preservation layer is composed of a color steel plate, a heat preservation benzene plate and a snowflake plate lining in sequence from outside to inside.

As shown in fig. 3, the embodiment of the present invention further provides a pretreatment method using the pretreatment apparatus for sweet potato storage as described above, comprising:

step S300: cleaning the sweet potatoes after the basket is filled. Specifically, the cleaning may be performed directly in the cleaning chamber 20, or may be performed manually outside the apparatus.

Step S400: the cleaned sweet potato basket filled with the sweet potatoes is sent into a callus chamber 1, the temperature in the callus chamber 1 is 60-65 ℃, the relative humidity is 20-30%, and the wind speed is at least 0.5m/s, and the callus treatment is carried out for 20-40 min.

Step S500: transferring the sweet potatoes after the callus treatment into a cooling chamber 2, wherein the temperature of the cooling chamber 2 is 15-20 ℃, the relative humidity is 20-30%, and the wind speed is at least 0.5m/s, and carrying out cooling treatment;

step S600: and taking out the sweet potatoes for storage after the temperature of the sweet potatoes is reduced to below 18 ℃.

Further, before step S300, the method further includes:

step S100: cleaning the harvested fresh sweet potatoes, removing soil impurities on the surfaces of the fresh sweet potatoes, and removing the sweet potatoes with diseases and insect pests.

Step S200: the sweet potatoes after selection are respectively put into sweet potato baskets 16, the height of the sweet potato baskets is less than or equal to two thirds of the height of the sweet potato baskets 16, and the sweet potatoes are placed in a cool and ventilated place for treatment after the sweet potato baskets are filled.

This is described below in connection with a specific embodiment.

The variety of sweet potato tuber used in this example was sweet potato red-heart 'Niyan potato 25', produced from sweet eastern water. The embodiment provides a method for pretreating a sweet potato with a damage, which comprises the following steps:

step S100, selecting: the harvested fresh sweet potatoes (containing damaged sweet potatoes) are cleaned of soil impurities on the surfaces of the tuberous roots of the sweet potatoes, and the sweet potatoes with diseases and insect pests are removed.

Step S200, basket loading: sweet potatoes of different specifications are respectively put into sweet potato baskets 16 (the length is multiplied by the width is multiplied by the height is multiplied by 510mm multiplied by 320mm multiplied by 155mm), as shown in figure 4, the sweet potato baskets are not higher than two thirds of the position (the scale mark position in figure 4) in the sweet potato basket 16, twelve sweet potatoes are stacked together in each batch of sweet potato processing, and the sweet potatoes are placed in a cool and ventilated place for processing after being bagged.

Step S300, cleaning: washing the sweet potatoes after being bagged by clear water, so that large soil on the surfaces of all the sweet potatoes is washed away; the washing can be carried out manually outside the equipment, or the sweet potato baskets 16 filled with sweet potatoes can be directly stacked in two rows (as shown in figure 4) horizontally and vertically, placed on the loading trolley of the sweet potato storage pretreatment equipment, and pushed into the cleaning chamber 20 for automatic cleaning.

Step S400, high-temperature short-time callus pretreatment: the site of treatment for this experiment was at the pilot test site of the eastern water, 10 and 20 months in 2019, and the local temperature was 15.5 ℃. And (3) opening the heating device 6 for preheating in the first half hour of treatment, and simultaneously starting the first air supply fan 3 and the second air supply fan 4 to adjust the air speed. Then the loading trolley loaded with sweet potatoes is sent into the callus chamber 1 through a slide rail 15, and the sweet potatoes are placed in the constant-temperature constant-humidity callus chamber 1 with the temperature of 60-65 ℃, the relative humidity of 20-30% and the wind speed of 0.5m/s for heat shock treatment for 25 min.

Step S500, cooling pretreatment: the callus sweet potatoes are continuously placed on a small trolley and then enter a cooling chamber 2 rapidly cooled by strong wind along with a slide rail 15, the temperature is the ambient temperature, the relative humidity is 20-30%, and the wind speed is 1m/s, and the sweet potatoes are cooled for 10 min.

Step S600, storage: after the temperature of the sweet potato root tuber is reduced to below 18 ℃, the sweet potato root tuber is placed in a storage cellar or a cold storage with the temperature of 13 +/-1 ℃ and the relative humidity of 80-90 percent for storage.

Device performance verification: the stability of the equipment and the uniformity of the sweet potatoes after pretreatment in the process of healing and cooling the sweet potato storage pretreatment equipment of the embodiment are described by testing the temperature and humidity parameters of the equipment in the process of healing and cooling the sweet potatoes after selection, basket loading and cleaning in the sweet potato storage pretreatment equipment of the embodiment.

(1) Selecting and basketing: fresh sweet potatoes which are regular in appearance, uniform in size (weight of 200-300 g), free of damage and diseases and insect pests are selected from the field, collected in the sweet potato Siheshui, and then are bagged according to the method shown in figure 4 to wait for equipment pretreatment.

(2) High-temperature short-time callus-strong wind cooling pretreatment: sweet potatoes are pretreated according to the pretreatment mode of the embodiment.

(3) Collecting equipment data: in the actual operation process of the device, the temperature and humidity data collected by the temperature and humidity sensor probes in the callus chamber 1 are collected and recorded every minute.

(4) Sample surface and core temperature determination: after each batch of sweet potatoes are subjected to heat shock callus pretreatment or cooling pretreatment according to the pretreatment method of the embodiment, the surface temperature and the core temperature of the sweet potatoes in the upper, middle and lower layers in two rows of 12 baskets in the same batch are measured according to the sampling method illustrated in fig. 4. The measurement method is as follows: immediately after taking out the pretreated sweet potatoes from the sweet potato basket 16, three points were randomly measured on the upper, middle and lower sides of the surface layer (3mm depth) and the inside (30mm depth) of each sweet potato using a probe thermometer, the surface layer and the inside temperature were recorded, respectively, and the average value of all the sampling points was calculated.

FIG. 5 shows the temperature changes detected by the temperature sensor probes in the callus chamber 1 during the high-temperature short-time callus formation of sweet potato in the callus chamber 1. The test result shows that the callus chamber 1 in the device has uniform temperature control and small fluctuation in the running process of high-temperature short-time callus. The temperature sensors at six different positions, namely the upper position, the lower position, the middle position and the rear position, monitor the highest temperature of 64.84 ℃, the lowest temperature of 63.02 ℃, and the temperature difference is only 1.82 ℃. The test result shows that the callus chamber 1 in the device has better temperature stability when processing 750kg results in large batch, and can heat and shock sweet potatoes in different placing positions uniformly, thereby ensuring the heat shock effect.

FIG. 6 shows the change of humidity detected by each humidity sensor probe in the callus chamber 1 during the high-temperature short-time callus treatment of sweet potato in the callus chamber 1. Because the cleaning process is involved in the pretreatment process of the equipment, a large amount of moisture is adhered to the surface of the sweet potato, the treatment uniformity of the subsequent high-temperature short-time heat shock process is influenced, the high-humidity load is caused to the components in the equipment, and the service life of the equipment is influenced. Therefore, the problems can be solved by arranging the electric air inlet valve and the moisture exhaust fan in the equipment. The test result shows that the humidity of the callus chamber 1 in the device is well controlled in the process of running high-temperature short-time callus. The average humidity of the six probes is 25.45%, and the humidity fluctuation is within 2.5%. The test results show that the callus chamber 1 in the apparatus of the present invention has better humidity stability when processing 750kg results in large batches, does not cause the problem of excessive humidity in narrow chambers, and ensures the heat shock effect.

FIG. 7 shows the temperature of the outer skin and inner core (i.e., sweet potato center) of sweet potatoes in bulk after a high-temperature short-time callus process in the callus chamber 1. After the sweet potato is subjected to the heat shock pretreatment in the callus chamber 1, the skin temperature of the sweet potato is generally lower than the core temperature, the skin temperature is between 37.78 and 39.70 ℃, and the difference of the skin temperature of the sweet potato at each sampling point is not more than 2 ℃; the temperature of the inner core is between 40.22 and 40.88 ℃, and the temperature difference of the inner core of the sweet potato at each sampling point is not more than 0.7 ℃. The test result shows that the high-temperature short-time heat shock equipment in the equipment has uniform heating effect on the sweet potatoes, does not have large temperature difference, and ensures that the sweet potatoes processed in the same batch at different positions can be well pre-treated by heat shock.

FIG. 8 shows the temperature of the outer skin and inner core (i.e., sweet potato center) of a batch of sweet potatoes after the rapid cooling process by strong wind in the cooling chamber 2. In the traditional sweet potato pretreatment flow, the cooling process after heating is not specially designed, so that the sweet potatoes stacked and bagged are not uniformly cooled after being heated, and are slowly cooled in the storage process, the premature aging of the sweet potatoes is stimulated, and the surfaces of the sweet potatoes form respiratory condensate water, so that a large amount of rotting is caused. In the integrated pretreatment equipment, sweet potatoes are specially cooled by the cooling chamber 2. The test result shows that after the sweet potato is cooled and pretreated by the cooling chamber 2, the skin temperature of the sweet potato is also lower than the core temperature, the skin temperature is rapidly reduced to 14.82-15.44 ℃ from 37.78-39.70 ℃ after heat shock, and the difference of the skin temperature of the sweet potato at each sampling point is not more than 1 ℃; the temperature of the inner core is reduced to 15.26-16.58 ℃ from 40.22-40.88 ℃ after heat shock, and the temperature difference of the inner core of the sweet potato at each sampling point is not more than 1.5 ℃. The test result shows that the cooling effect of the cooling equipment in the equipment disclosed by the invention on the thermally excited sweet potatoes is obvious, the cooling effect is uniform, and large temperature difference does not occur, so that the sweet potatoes processed in the same batch at different positions can be well cooled and pretreated, and the quality of the sweet potatoes in the storage process is ensured.

And (II) testing and verifying the performances of the pretreated sweet potatoes: the following 1 example and 4 comparative examples are used to compare and verify the performance indexes of sweet potatoes which are subjected to callus and cooling pretreatment in the sweet potato storage pretreatment equipment. In order to avoid the influence of the difference of the wound on the test result, the experiment is carried out by using the sweet potato tuber after artificial injury.

The specific method comprises the following steps:

(1) selecting: fresh sweet potatoes which are regular in appearance, uniform in size (weight is 200-300 g), free of damage and diseases and insect pests are selected from the field and collected in the sweet potato Siheshui.

(2) Artificial injury: in order to ensure the accuracy of the experiment, the sweet potatoes used for the experiment are subjected to artificial wound manufacturing. Wiping a skin scraping knife and a puncher (the diameter is 20mm) with 95% ethanol for disinfection, firstly, making a circular mark with the radius of 1cm on each sweet potato by using the puncher, then, scraping wounds with the diameter of 2cm and the depth of 3mm on the surface of the sweet potato along the marked part of the puncher by using the skin scraping knife, and dividing each sweet potato into an upper wound, a middle wound and a lower wound which are 6 parts; the skin-scraping knife is a stainless steel foot filing knife (the length is 190mm, the width is 26mm, and the thickness is 15 mm).

(3) The artificially injured sweet potatoes were randomly sampled and used as samples of example 1 and comparative examples 1 to 4, respectively, 400 sweet potatoes were treated for each group, and 3 groups were repeated. Wherein:

example 1 an experiment was performed according to the sweet potato storage pretreatment method provided in this example, and the steps S100 to S600 were sequentially performed.

Comparative example 1 is a blank control without any pretreatment, and after the steps S100 and S200, the cleaning-callus-cooling treatment was not performed, and the step S600 was directly performed, i.e., sweet potatoes were selected, bagged, and then directly placed under an environmental condition of 13 ± 1 ℃ and a relative humidity of 80-90%, and stored in a warehouse (constant temperature climatic chamber).

Comparative example 2 the most common method for cleaning sweet potato and pre-treating it with low temperature and short time for healing in commercial, experimental and agricultural (actual production and experimental research) is used, which is basically the same as the treatment of example 1 except that: after steps S100 to S300, in step S400, a long-time low-temperature heat shock treatment is performed in the storage cellar or the storage warehouse at a temperature of 35 ℃ for 2 days, and then step S600 is performed without performing step S500.

Comparative example 3 employed a method of washing pretreated sweet potatoes which was generally the same as that of example 1 except that: after the steps S100 to S300, the step S600 is directly performed, namely, the storage is directly performed after the selection, the basket filling and the cleaning.

Comparative example 4 employed a method for pretreating sweet potatoes using the apparatus of the present invention without performing a washing step, which was substantially the same as that of example 1 except that: after the steps S100 to S200, the step S300 is not carried out, and the steps S400 to S600 are directly carried out, namely, after the selection and the basket filling, the cleaning is not carried out, the high-temperature short-time callus treatment and the cooling pretreatment are directly carried out by using the equipment of the invention, and then the storage is carried out.

(3) Testing and sampling: taking the day of treatment as day 0, sampling sweet potatoes in example 1 and comparative examples 1-4 every 7 days, wherein the number of each group of sweet potatoes in each sampling is not less than 10kg, the last sampling is the storage day 35, testing I-V (respectively testing color, browning, respiration, hardness and cell membrane permeability) is carried out, and the rest samples are stored at-20 ℃ and wait for testing VI-twelve;

after 7 days of callus formation (callus period from the time of lesion formation to the end of storage) in each of example 1 and comparative examples 1 to 4, the treatments were sampled for the remaining tests. Specifically, after the treatment of example 1 and comparative examples 2 to 4, the samples were stored for the 7 th day; samples were taken on day 5 of storage after 2 days of heat shock treatment in comparative example 1.

The test results were as follows:

(a) testing one: color test

The color was determined as follows: the color difference of the sweet potato wound is measured by a 3nh spectrocolorimeter, the L, a and b values of the tissue parts which are respectively vertical to the tuberous root of the sweet potato are measured, and the data are recorded and averaged. 20 sweet potato tubers were taken for each treatment and assayed.

The color of the section of the tuberous root of the sweet potato of example 1 and each proportion was observed in the test, and the sweet potato treated and stored in example 1 was analyzed comprehensively for the influence of heat shock treatment on the color of the sweet potato during storage by measuring the color difference of the pulp tissue of the sweet potato during storage to obtain the L, a and b values of the sweet potato. As can be seen from fig. 9 to 11, the sweet potato showed no significant difference in L, a and b values among the groups at the early stage of storage (0d, 7d and 14d), but the sweet potato of comparative example 1 without any pretreatment showed a tendency of a sharp decrease in L and b values and a sharp increase in a value with the increase of storage time, and the color of the sweet potato tissue was gradually changed from light brown to brown by observation. The L value of comparative examples 3 and 4 dropped significantly below 60, but was significantly higher than comparative example 1. Whereas the L values of comparative example 2 and example 1 remained the highest brightness after 35 days of storage and there was no significant difference between the two groups. The results of the L values show that the final brightness of the fruit can be effectively improved by the four pretreatment methods compared with the untreated groups, the process of the shade of the color is obviously inhibited, and the improvement of the brightness is the largest in the example 1 and the comparative example 2. In addition to comparative example 1, the a values of comparative example 3 and comparative example 4 also showed a tendency to increase greatly, but were smaller than comparative example 1. The a values of the example 1 and the comparative example 2 show a descending trend, which shows that the pretreatment mode of the example 1 and the comparative example 2 can effectively inhibit the degree of the browning of the fruits. Except for comparative example 1, the b values of the other four groups have small differences and small reduction amplitude, and the original color b value of the sweet potato is basically maintained.

(b) And (2) testing: test for browning degree

The method for measuring the browning degree comprises the following steps: and 6 sweet potato samples are randomly taken from each group of treatments and transversely cut, the sweet potato samples are placed for 4 hours in a normal temperature environment, the color difference (L, a and b) inside the sweet potato tissues is measured by using a color difference meter, and the total color difference delta E is calculated according to the color difference values of the two times, namely the browning degree. The calculation formula is as follows:

in the formula: and delta L, delta a and delta b are the color difference values before and after browning of the sweet potato sample before and after treatment respectively.

The browning is a main characteristic of fruit and vegetable maturation aging and physiological decline, and during the storage process of the fruit and vegetable, the browning phenomenon of the fruit and vegetable tissues is easier to occur along with the time extension, which is mainly shown in the change of the color of the fruit and vegetable from bright to dark, so that the total color difference delta E can be calculated by utilizing the color difference degrees of the sweet potato sections twice under the same conditions and the same time, and the easy browning degree of the sweet potato root tuber is evaluated.

From the effect of the heat shock treatment on the browning level of sweet potatoes during storage, it can be seen from FIG. 12 that the browning level of sweet potato tissues gradually increased, and there was no significant difference between the groups until the 7 th day of storage, after which the browning level of comparative example 1 sharply increased and reached 77.8 at the 35 th day of storage. In contrast, between comparative examples 2 and 4, there was no significant difference at each sampling point, and the browning level was low and maintained at about 40 at 35 d. Comparative example 3 the browning level was close to that of comparative example 2 and comparative example 4 in the course of 0d to 28d, but increased to 59.0 at 35d, indicating that the sweet potato pretreated in comparative example 3 was susceptible to browning during the later period of storage. Example 1 was the group of five pretreatment regimes that was most effective in inhibiting browning, with the degree of browning maintained at the lowest level throughout storage, and the final degree of browning at 35d was 38.9, significantly lower than the other four groups. The test experiment result shows that the sweet potato treated by the equipment and the pretreatment process can effectively reduce the browning degree of the sweet potato after being stored, and the physiological aging process of the sweet potato is effectively delayed.

(c) And (3) testing: breath strength test

The method for measuring the breathing intensity comprises the following steps: the respiration rate was measured by using a fruit and vegetable respiration analyzer (model FS-3080A). In each example, 5 sweet potatoes are randomly selected, weighed and placed in a fruit and vegetable respiration determinator for determination, the respiration intensity of each treatment is calculated by using respiration intensity software, and the average value is taken and repeated three times, wherein the average value is expressed in mg/kg.h.

The respiratory metabolism of fruits and vegetables is closely related to the synthesis and catabolism processes of various organic macromolecular substances, and sweet potatoes which are not pretreated usually have obvious respiratory peaks in the early storage period, and metabolize a large amount of carbon dioxide and water vapor, and the phenomenon is called 'sweating' in the actual production. Under the condition of poor ventilation under the storage condition, a large amount of water vapor is condensed and attached to the surface of the sweet potato to easily cause the rotting phenomenon, thereby causing negative influence on the storage of the sweet potato. As can be seen from the effect of different pretreatment techniques on the respiration intensity during storage of sweetpotato in FIG. 13, the respiration intensity of each group of treated sweetpotato showed different trends. The untreated group of comparative example 1 exhibited a significant peak in respiration on day 7, after which the respiration intensity continued to decline; the sweet potatoes of the cleaning pretreatment group of comparative example 3 also exhibited a respiratory peak on day 7 of storage, and the peak value of the respiratory intensity was significantly higher than that of comparative example 1, showing a downward trend after the respiratory peak. This indicates that the washing treatment may cause the sweet potato to increase in respiration intensity due to exogenous physical stimulation. The other three callus pretreatment groups all show inhibition effect on the sweet potato respiration intensity, and no obvious peak appears during storage. There was no significant difference in the respiration intensity between example 1 and comparative example 4, and comparative example 2 showed a small increase in respiration intensity after 14 days. The heat shock in the callus pretreatment after harvesting can effectively inhibit the abnormal fluctuation of the sweet potato respiration intensity in the storage process, and the sweet potato groups (example 1 and comparative example 4) treated by the device of the invention have the most obvious inhibition on the respiration intensity.

(d) And (4) testing: hardness test

The hardness measurement method comprises the following steps: cutting sweet potato into cylinders, placing sweet potato meat tissues at the head and tail parts and the most middle part of the sweet potato on a carrying flat plate of a texture analyzer, and measuring the hardness of the sweet potato tissues by using a cylindrical probe to obtain an average value, namely the hardness of the sweet potato tissues.

The hardness of the fruits and vegetables is an important index for measuring the storage quality of the fruits and vegetables, and in the storage process, the hardness of the fruits and vegetables is gradually reduced along with aging to generate a softening phenomenon, but the sweet potatoes are likely to be flocculent due to water loss to cause the hardness to be rapidly increased. As can be seen from FIG. 14, the hardness of the sweet potato tissue inside gradually decreased with the increase of storage time, the hardness of comparative example 1 did not decrease rapidly from day 7, and finally the hardness of sweet potato in the middle part was only 3.87g, which is probably due to incomplete healing of the wound of sweet potato, the sweet potato defense ability decreased, and the aging process of sweet potato was accelerated. The hardness of the final middle part of the sweet potato subjected to the four pretreatment modes is generally higher than that of the sweet potato subjected to the comparative example 1. Among them, the sweet potato of example 1 showed the slowest decrease in hardness and finally the highest hardness at the center part, which reached 5.91 g. From FIG. 15, it can be seen that the hardness of the sweet potato at the head and tail parts shows different trend, and the hardness of the sweet potato at the two head parts of the comparative examples 1 and 3 shows a sharp increase from 21d, which may be caused by two reasons: firstly, because the sweet potatoes are stressed by low temperature during storage, the sweet potatoes are subjected to cold damage, and two head parts are flocculent and hardened; secondly, because the two head parts of the sweet potato are the fibrous root parts of the tuberous root, the sweet potato is mainly used for absorbing soil nutrients, the permeability of cell membranes is strong, and the sweet potato becomes hard due to severe dehydration and drying shrinkage caused by improper storage environment in the storage process. On the other hand, the sweet potatoes of example 1, comparative example 2 and comparative example 4 have the hardness at the head and tail parts consistent with the change trend of the inside of the tissue due to the callus pretreatment process, and the hardness shows a decreasing trend, wherein the decreasing rate of example 1 is slower, the final head and tail hardness keeps the highest value, and the hardness at the middle part is consistent with the result. This shows that the heat shock in the callus pretreatment after harvesting has a positive effect on delaying the decrease of the hardness of the sweet potatoes, and the sweet potato hardness protection effect after the pretreatment by the equipment of the invention is the best.

(e) And testing: cell membrane permeability test

Method for measuring cell membrane permeability: firstly, randomly taking the potato flesh tissue in the sweet potato tissue by using a puncher with the diameter of 15mm, and then cutting the potato flesh tissue into small circular sheets by using a stainless steel knife. And during measurement, 30 cut small discs are placed in a 50mL centrifuge tube, 20mL distilled water is poured into the centrifuge tube for soaking, the mixture is stirred by a blending instrument to be uniform, water is poured out, the mixture is repeatedly washed for three times, and then the mixture is placed on absorbent paper to absorb water on the surface of the slice. Placing the sheet in a 500mL big beaker, adding two thirds of distilled water, standing at normal temperature for 60min, and measuring the initial conductivity r₁. Then, the distilled water in the beaker was boiled for 10min, cooled and measured as r again₀. And (4) calculating a result:

in the formula: r_eIs the relative conductivity; r is₁Conductivity of the sweet potato living tissue leaching liquor; r is₀Conductivity of the leaching liquor after the living tissue of the sweet potato is killed.

The stress resistance and the injury degree of the fruits and vegetables can be expressed by the conductivity. When the fruits and vegetables are continuously aged or are influenced by cold damage, diseases and other adverse effects along with the prolonging of the storage time, cell membranes of the tissues of the fruits and vegetables are damaged, and electrolytes in the cell membranes are leaked outwards to cause the increase of the conductivity of the extracting solution. As can be seen from FIG. 16, the cell membrane permeability of each group of treatments gradually increased with the increase of the storage time, and at the time of 7d storage, the cell membrane permeability of each group of treatments greatly increased without significant difference, because the cell membrane permeability was high during the wound healing process of the damaged tuberous root of Ipomoea batatas. In the storage of 14d to 35d, the cell membrane permeability was gradually increased in the groups other than example 1. The increase in cell membrane permeability was greatest in the untreated group of comparative example 1, and finally reached 0.849%, which was significantly higher than that in the other pretreated groups. Comparative example 3 the final cell membrane permeability of the sweet potato washed and pretreated was inferior to that of comparative example 1 and was much higher than that of comparative examples 2 and 4, indicating that the washing pretreatment may not contribute well to long-term storage of sweet potatoes. The cell membrane permeability of example 1 increased after a small decrease at day 14, and finally the cell membrane permeability was the lowest (0.72%) of all pretreatment groups, which shows that the device and pretreatment process of the invention have a positive effect on the increase of cell membrane permeability during the storage period of sweet potatoes, and can improve the callus effect and delay the senescence process of sweet potatoes.

(f) And (6) testing: malondialdehyde content test

The determination method of the content of malondialdehyde comprises the following steps: weighing 1g sweet potato sample, adding 5mL of 100g/L trichloroacetic acid (TCA) solution, grinding, homogenizing, centrifuging (4 deg.C, 10000r/min, 20min), collecting supernatant, and keeping at low temperature. 2mL of the supernatant was added with 2mL of 0.67% thiobarbituric acid (TBA), mixed and incubated in a boiling water bath for 20min, cooled and centrifuged once, and the absorbance was measured at 450nm, 532nm and 600nm, respectively. According to the absorbance value of the solution, the content of the malonaldehyde in the reaction mixed solution is calculated, and the content of the malonaldehyde in the fresh weight of each gram of tissue sample is calculated and expressed as mu mol/g FW.

C(μmol/L)＝6.45×(OD532-OD600)–0.56×OD450

In the formula: OD532, OD600, OD450 represent absorbance values measured at 532nm, 600nm and 450nm, respectively.

In the formula: c is the concentration of malonaldehyde in the reaction mixed solution, mu mol/L; v is the total volume of the sample extracting solution, mL; vs is the volume of the extracted solution of the sample in mL; m is the sample mass, g.

During storage of fruits and vegetables, ROS free radicals generated in tissues can induce peroxidation of unsaturated fatty acids in membrane lipids to generate Malondialdehyde (MDA) due to adverse stresses such as aging or cold damage, diseases and the like. Therefore, the content of the malondialdehyde can prevent the damage degree of the histiocyte of the fruit and vegetable due to aging, cold damage and diseases. As seen from FIG. 17, the MDA content of each group of the sweet potatoes during storage tended to increase, decrease and increase. At 7d of storage, all groups of MDA declined after a small peak, due to the fact that sweet potato wounds produced a large amount of reactive oxygen species during the healing process during the initial period of storage to promote wound healing. In the middle and later storage periods, the MDA content gradually rises, when the storage period reaches 35d, the MDA content of the untreated comparative example 1 group is the highest (4.267 mu mol/g), and the inferior grade of the cleaning treatment of the comparative example 3 is not obviously different from that of the comparative example 1. The final MDA levels of comparative example 2, comparative example 4, and example 1 were lower than the two groups above, with example 1 having the lowest 35d MDA level (3.334 μmol/g). The method shows that the pretreatment and the non-treatment of the clear water have no obvious effect on the senescence and adversity stress of the sweet potatoes, and the callus pretreatment modes can effectively delay the accumulation of the MDA content in the storage of the sweet potatoes and reduce the peroxidation damage of the sweet potatoes, thereby slowing down the senescence of the sweet potatoes. The sweet potato treated by the equipment and the pretreatment process has the best effect.

(g) And test seven: cold damage test

The method for measuring the cold damage comprises the following steps: during the storage period of the sweet potatoes, the occurrence rate of the sweet potatoes in the cold damage index rating table is counted and calculated according to the standard of the sweet potato cold damage index rating table, and is shown in the following table.

TABLE 1 sweet potato index rating table

The calculation formula of the cold damage rate is as follows:

the cold injury is a phenomenon that the final storage property and edibility are influenced by a bad adverse environment phenomenon caused by the fact that the temperature of the fruits and the vegetables is lower than a specific cold sensitive line of the fruits and the vegetables in the storage process, and the sweet potato cold injury is mostly flocculent, water-soaked and microorganism-free rotten phenomena reported. As shown in fig. 18, the cold damage rates of the respective treatments tended to increase gradually as the storage time extended over the entire storage period. When the sweet potatoes are stored for 7d, the cold damage rate of the sweet potatoes in each group is lower than 0.12 percent. From day 14 onward, the incidence of chilling injury in the cleaning pretreated sweet potatoes of comparative example 3 increased greatly, and a sharp increase in the tendency appeared on day 21. The reason for this is probably that the sweet potato is not dried by strong wind after cleaning and pretreatment, and the surface humidity of the sweet potato is too high, which leads to higher water activity and leads to that the sweet potato is more easily damaged by cold. The non-treated group of comparative example 1 showed a large increase on day 21 and a sharp increase on day 28, and the incidence of cold damage was slightly lower than that of comparative example 3. The final cold damage incidence rate of sweet potatoes in other three callus pretreatment groups is less than half of that of comparative example 1 and comparative example 3, wherein the effect of example 1 is the best, and the final cold damage incidence rate is 0.877 percent and is obviously lower than that of other four groups. The result shows that the cold resistance of the sweet potatoes is obviously improved through the heat shock process of the callus pretreatment, and the final storage quality of the sweet potatoes can be improved.

(h) And testing eight: test for rotting Rate

Determination method of rotten rate: the rotting rate of sweet potato was counted and calculated during storage according to the standard of the sweet potato rotting index rating table as shown in the following table.

TABLE 2 sweet potato rot index rating table

The decay rate is calculated as follows:

the rotting rate is an important index for measuring the storage effect of the sweet potatoes. The sweet potato has thin skin and high water content, is easy to scratch, and the damaged part is very easy to be infected by germs in the storage process to cause sweet potato rot. As can be seen from FIG. 19, the rotting rate of sweet potato gradually increased during storage, and the rotting rate of each group of sweet potato was not higher than 0.2% and was not significantly different when stored for 7 days. After day 7, a gradual increase was started, wherein the decay rates of comparative example 1 and comparative example 4 were significantly higher than those of the other three groups, and the decay rates of comparative example 1 and comparative example 4 were 4.9% and 2.76% on day 35, respectively. The final rot rate of the remaining three groups was less than 1.2%, less than half that of comparative example 4. Wherein, the rot inhibition effect of example 1 is the best (0.54%), only the individual sweet potatoes have dull surfaces, local mildew spots appear on the wounds, and the humidity control is improper during the storage process, which may cause the growth of mold. The rotting rate result shows that the callus pretreatment has a certain effect on the rotting rate, but the rotting rate of the sweet potatoes which are not subjected to cleaning pretreatment cannot be well controlled, and the rotting rate of the sweet potatoes which are subjected to the equipment and pretreatment of the invention has the best inhibition effect.

(i) And testing nine: weight loss rate test

The weight loss rate measuring method comprises the following steps: the weight loss rate of the sweet potatoes is measured by a weighing method, 30 sweet potato tuberous roots are selected for each treatment, the treatment is divided into three groups of 10 sweet potatoes, the weight of the sweet potatoes is tracked and measured, the weight loss rate of each group of the sweet potatoes is calculated according to the following formula, and then the average value is calculated.

Transpiration water loss is the main cause of weight reduction of fruits and vegetables. When the fruits and vegetables are infected by mechanical damage or diseases, the water transpiration speed is accelerated, the weight of the fruits and vegetables is reduced, and the callus formation can effectively prevent the water transpiration, reduce the weight loss and maintain better commodity. As is clear from FIG. 20, the weight loss ratio of sweet potatoes gradually increased over the storage period. The sweet potato dehydration phenomenon of the untreated group in the proportion 1 is more serious than that of the other four treatment groups in 14-35 days, and the final weight loss rate reaches 17.82%. Comparative example 3 the cleaning pretreatment can keep the weight loss rate of the sweet potato significantly lower than that of comparative example 1 before 21 days, but after 21 days, the weight loss rate is sharply increased, and the difference between the final weight loss rate and the comparative example is not large and reaches 16.87%. In the other three callus pretreatment groups, the example 1 and the comparative example 4 can stabilize the final weight loss rate within 10 percent, and the effect of controlling water loss is obvious. The weight loss of the sweet potatoes can be effectively reduced through the equipment and the pretreatment, and the aim of maximally reducing the product loss after storage is fulfilled.

(j) And (5) testing: starch content test

The method for measuring the starch content comprises the following steps: determination of starch: measured by an acid hydrolysis method, and expressed as mass fraction (%).

Starch is the most common energy supply substrate for tuber crops in the post-harvest process, and as seen from figure 21, the starch content in sweet potatoes is in a whole descending trend due to the consumption of energy substances stored in the sweet potatoes in the storage process, and a small-amplitude return rise occurs in the middle. The starch content of example 1 decreased more slowly overall during storage, and a small peak of rising amplitude occurred on day 21. Comparative example 4 was also treated using the apparatus of the present invention, and the trend was the same as in example 1. Comparative example 1 the sweet potato starch content of the untreated group was the most severely reduced by 75% compared to the original origin. The experimental result shows that the sweet potato pretreated by the device can retain more starch content in the storage process, thereby obtaining the sweet potato with better eating and selling quality.

(k) Test eleven: soluble sugar content test

The method for measuring the content of the soluble sugar comprises the following steps: measured by the phenol-sulfuric acid method, and expressed in mass fraction (%).

The soluble sugar is used as an important energy storage substance in the tissues of fruits and vegetables, the content of the soluble sugar is closely related to the quality and the storability of the fruits and vegetables, and the sweet potatoes with high sweetness are more easily loved by consumers. The effect of postharvest heat shock treatment on the soluble sugar content of damaged sweet potatoes during storage is shown in FIG. 22, wherein the soluble sugar content of sweet potatoes gradually increases along with the increase of storage time, and is opposite to the change trend of starch. The rate of increase of soluble sugar content of sweet potato of example 1 was the fastest in the early stage because the sweet potato was subjected to pretreatment by the apparatus of the present invention and energy was consumed for the rapid callus. The sweet potato soluble sugar content of example 1 and comparative example 2 reached 7.73% and 7.67% at 35d of storage, which was the highest for all pretreatment groups. The sweet potato of comparative example 1 has a final soluble sugar content of only 6.54%, and as a result of combining the starch content and the soluble sugar content, it was found that comparative example 1, which is not treated at all, may cause a greater metabolic consumption of the sweet potato during storage, thereby causing loss of starch and sugar, which affects the quality of sale. The result shows that the equipment and the pretreatment can effectively reduce the metabolic consumption in the storage process of the sweet potatoes, better keep the edible quality of the sweet potatoes and have important significance for the actual production.

(l) And a twelfth test: ascorbic acid content test

Determination method of ascorbic acid: the mass of ascorbic acid contained in a fresh weight of 100g of the sample, i.e. mg/100g, was determined by spectrophotometric method.

The content of the ascorbic acid is one of important indexes for evaluating the nutritional quality and the storage effect of the fruits and vegetables. Along with the reduction of the freshness of the fruits and vegetables, the content of the ascorbic acid is also reduced continuously, so that the content of the ascorbic acid reflects the quality effect of the fruits and vegetables during storage. As can be seen from the experimental results shown in fig. 23, the sweet potato of example 1 had the least decrease in the ascorbic acid content, which was significantly higher than other groups at 35 days, and decreased by 44.6% from the initial one. Comparative example 1 dropped most significantly, and finally dropped 83.8% from the initial. The other three pretreatment groups are respectively arranged between the example 1 and the comparative example 1, which shows that other pretreatment modes can effectively keep the ascorbic acid content of the sweet potatoes after storage and ensure the quality of the sweet potatoes after storage; but the effect after the pretreatment by the equipment and the process is better and outstanding.

According to the embodiment, the sweet potato storage pretreatment equipment and the pretreatment method provided by the invention have the advantages that the sweet potato storage pretreatment equipment performs high-temperature short-time callus treatment on sweet potatoes through the callus chamber 1, the injured pericarp of the sweet potatoes is quickly healed by utilizing a mode of thermally stimulating and regulating metabolic pathways and killing epidermal microorganisms at high temperature to form a biological barrier for resisting external disease microorganisms, the sweet potatoes after callus are quickly cooled by strong wind through the cooling chamber 2, the residual temperature of the sweet potatoes after callus is quickly reduced, the increase and the loss of respiratory strength in the storage process are avoided, and the rotting condition in the early stage of storage is reduced. The sweet potato storage pretreatment equipment can effectively accelerate the formation of the callus of the tuberous roots of the sweet potatoes and shorten the pretreatment time by carrying out high-temperature short-time callus-cooling pretreatment on the sweet potatoes before postnatal storage by a green pollution-free physical method, thereby achieving the purposes of reducing the rot and water loss of the sweet potatoes in the storage period, ensuring the storage quality and prolonging the storage period.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. The sweet potato storage pretreatment equipment is characterized by comprising a callus chamber and a cooling chamber, wherein the callus chamber and the cooling chamber are oppositely arranged by an access door, one end of the callus chamber, which is far away from the cooling chamber, is connected with a first air supply fan, and a heating device is arranged between an outlet of the first air supply fan and the callus chamber; and one end of the cooling chamber, which deviates from the callus chamber, is connected with a second air supply fan.

2. The sweet potato storage pretreatment equipment as claimed in claim 1, wherein a return air duct is arranged above the callus chamber, an inlet of the return air duct is communicated with the inner chamber of the callus chamber, and an outlet of the return air duct is connected to an inlet of the first air supply fan; the lower part of the callus chamber is provided with a lower air supply duct, the inlet of the lower air supply duct is connected with the outlet of the heating device, and the outlet of the lower air supply duct is communicated with the inner cavity of the callus chamber.

3. The sweet potato storage pretreatment equipment of claim 2, wherein the top of the callus chamber is provided with a plurality of openable top windows in the length direction, and the inlet of the return air duct is communicated with the inner cavity of the callus chamber through the top windows.

4. The sweet potato storage pretreatment apparatus of claim 2, wherein the outlet of the heating device is connected to the inlet of the lower air supply duct and the air inlet of the callus chamber through a three-way regulating valve.

5. The sweet potato storage pretreatment apparatus of claim 1, further comprising a cleaning chamber disposed between the callus chamber and the cooling chamber, wherein a plurality of spray heads are installed in the cleaning chamber.

6. The sweet potato storage pretreatment apparatus according to claim 1, wherein a temperature sensor and a humidity sensor are installed in the callus chamber, and an electric air intake valve and a moisture exhaust fan electrically connected to the humidity sensor are further installed in the callus chamber.

7. The sweet potato storage pretreatment apparatus of claim 1, wherein a wet curtain is installed between the outlet of the second air supply fan and the cooling chamber.

8. The sweet potato storage pretreatment apparatus according to any one of claims 1 to 7, further comprising a slide rail and a loading trolley, wherein one end of the slide rail extends into the callus chamber and the other end of the slide rail extends into the cooling chamber; the loading trolley can slide along the slide rail.

9. A pretreatment method using the pretreatment apparatus for sweet potato storage according to any one of claims 1 to 8, comprising:

cleaning the sweet potatoes after being bagged;

10. The pretreatment method according to claim 9, further comprising, before the cleaning of the basket-packed sweet potatoes:

cleaning the harvested fresh sweet potatoes, removing soil impurities on the surfaces of the fresh sweet potatoes, and removing the sweet potatoes with diseases and insect pests;

and respectively putting the selected sweet potatoes into sweet potato baskets, wherein the height of the sweet potato baskets is less than or equal to two thirds of the height of the sweet potato baskets.