WO2021118491A1

WO2021118491A1 - Innovation in systems for explosion puffing drying of foods with microwave under vacuum

Info

Publication number: WO2021118491A1
Application number: PCT/TR2020/050352
Authority: WO
Inventors: Mehmet Solak
Original assignee: Rapi̇d Gida Teknoloji̇leri̇ İmalat Sanayi̇ Ve Ti̇caret Li̇mi̇ted Şi̇rketi̇
Priority date: 2019-12-10
Filing date: 2020-04-28
Publication date: 2021-06-17
Also published as: TR201919710A1

Abstract

The invention is a drying system (D) operating under vacuum, intended to be used for explosion puffing drying of foods such as fruits and vegetables, comprising a food supplying unit (1) which allows the food to be carried to the area of explosion puffing and drying areas, where; it comprises an explosion puffing unit (20) comprising at least one microwave heating source magnetron (21) which provides heat for explosion puffing of foods, a drying unit (30) and a cooling unit (40).

Description

INNOVATION IN SYSTEMS FOR EXPLOSION PUFFING DRYING OF FOODS WITH MICROWAVE UNDER VACUUM

Technical Field The invention relates to systems that provide explosion puffing drying of foods.

The invention in particular is related to microwave and steam - powered systems that provide explosion puffing drying of foods under vacuum.

State of the Art

Drying is one of the oldest methods used to preserve and maintain food for a long time. Drying process is defined as reducing the amount of moisture in foods. Thereby, the storage life of food is extended and reproduction of harmful microorganisms is slowed down.

Fruit and vegetables are one of the primary food products to which drying process is applied. Dried fruits and vegetables lose a large portion of the water they contain, reducing their weight and volume. This makes it easier to pack and transport dried fruits and vegetables. Dried fruits and vegetables can be stored for a long time without the need for artificial preservatives and additives. Thus, dried fruits and vegetables are more beneficial to human health than canned fruits and vegetables. Today, many methods are used for drying foods. The most common of these methods is drying where solar energy is utilized. In this method, foods are dried outdoors. In this case, dried foods are exposed to external factors such as dust, dirt and insects. This negatively affects the quality of dried products and human health. The application number TR2011 / 09258 describes a method for drying vegetables and fruits in a machine. The invention relates to an economical, fast, environmentally harmless, homogeneous and controlled drying method to provide long shelf life to vegetables and fruits, to save surplus products from wasting, to prevent waste of energy used in systems such as deep freezers or refrigerators. Drying processes which are conventionally conducted using machinery protect foods against external negative factors which effect product quality and human health since they are conducted indoors. However, in conventional and natural methods, heat is first transferred to the outer surface of the food and then to the inner parts. This gradual heat transfer causes the outer part of the food to dry and shrink more quickly. The hard layer caused by shrinkage prevents the transfer of heat to the inner parts and the moisture inside the product to outside of the product. The quality features of dried foods such as taste, appearance, color and nutritional value should change as little as possible, and when water is added to be cooked, they should be able to absorb water that is close to the amount they contain while fresh. Conventional systems and solar drying processes do not provide enough volume to dried fruits and vegetables.

In microwave drying method, since the electromagnetic field affects the food as a whole, unlike conventional drying methods, selective heating is performed by targeting water molecules directly within the product. In this method, heat is generated directly within the product. Moisture in the product is evaporated by heating in very short periods. Due to vapor pressure difference generated between the internal and external environment, moisture transfer is from inside to out. Thus, heat transfer, shrinkage and hard shell problems that occur in conventional drying methods are eliminated in microwave drying method. Although microwave drying may seem to be an advantageous drying method, there are many disadvantages. There are disadvantages such as high initial investment costs, causing loss of aroma and physical harm in foods, drying of products of a uniform structure in a certain size and shape, and requiring high safety measures. To eliminate these disadvantages, the microwave method is used in combination with various methods.

Document US2002017033 describes a method and apparatus for drying or heat treating substances or products under pressure other than atmospheric pressure. A microwave source is used for drying or heat treatment. In addition, an infrared heating source can be used. In the method of invention, the products which are to be dried or to which heat treatment will be applied are filled into containers from a transport receptacle. The products filled into the containers are transported to a treatment chamber which is under vacuum and where microwave and / or infrared heating source is used by means of a main conveyor. Products to which drying or heat treatment is applied are then transferred to a discharging lock chamber which is at atmospheric pressure. Carrier containers may be deformed under microwave and / or infrared heating sources. Therefore, carrier containers are replaced at certain periods. Manpower is used more commonly for filling and emptying of containers in drying foods with carrier containers. However, this manpower requirement is less in a drying process on a tray. Reuse of additionally refrigerated containers causes heat losses and waste of energy.

Document number EP2408322 describes a process and a mechanism for drying and buffering organic moist products. The device of the invention comprises three chambers. A certain amount of products to be dried and processed are placed in the first chamber on a metallic, in particular steel, round plate and heated by microwave by adjusting the pressure. Then the products taken to the second chamber are heated with infrared heating source by adjusting the pressure again. In the third chamber, the product is brought to ambient pressure and cooled. Use a container of made of steel or a different metal in the microwave heating source causes arc formation. In addition, these containers deform over time and changing the containers imposes additional costs. For these reasons, carrier vessels are not used in the explosion puffing drying system of the invention. Instead, products are carried with a tray system. Manpower is used more commonly for filling and emptying of containers in drying foods with carrier containers. However, this manpower requirement is less in a drying process on a tray. Reuse of additionally refrigerated containers causes heat losses and waste of energy.

The main purpose of commercial drying is to efficiently provide the necessary heat for the process. In existing systems, heating and cooling operations in adjacent areas or in the same area prevent efficient use of energy. The areas heated in drying processes lose some of their existing heat by cooling process and need to be reheated. This causes microwave and infrared heating sources, which already has high energy consumption, to consume more energy.

The initial investment and depreciation costs of microwave and infrared heating sources are high. For this reason, these processes are not frequently preferred for commercial in drying processes, alone or in combination.

The drying time is as important as the cost in the food drying process. In this case, it is not sufficient to provide only energy efficiency in order to reduce the costs of the processes. It is necessary to make the dryer system work continuously and systematically and to meet the drying process as soon as possible. Drying processes often come with high energy costs in order to dry products in a shorter time. However, product quality decreases especially when foods are dried at high temperatures. While microwave and infrared heating sources give good results in sugar - free foods, they cause caramelization in sugar - containing foods, resulting in quality losses.

In the drying system of the invention, foods are first explosion puffed by using a microwave heating source under vacuum. The drying process is sustained by steam energy under vacuum.

As a result, due to the negativity described above and the inadequacy of the existing solutions on the subject, an improvement in the relevant technical area has been made necessary.

Object of the Invention

The invention is inspired by existing situations and aims to solve the disadvantages mentioned above.

The main purpose of the invention is to produce dried foods with high product quality through a combination of vacuum, microwave and steam energy.

Another purpose of the invention is to reduce high investment and depreciation costs by using a microwave heating source only during the explosion puffing phase. In this way, the number and use of magnetrons used to generate microwaves is significantly reduced. Another purpose of the invention is to prevent sugary foods from being caramelized by combining microwave and steam energy. Conducting the drying process with steam energy allows sensitive adjustment of temperature. This prevents factors that negatively effect the product quality such as burning and blackening especially in the drying process of sugary products.

Another purpose of the invention is to prevent the disadvantages of drying carried out using container by ensuring that dried products are carried on a tray. In particular, metal containers used with microwave heating source are prevented from creating arc to pose a safety risk.

Another purpose of the invention is to ensure that the drying process is carried out at low temperatures (35 - 40 Ό) and that the n utritional values of foods such as vitamins and minerals are maintained.

Another purpose of the invention is to prevent energy waste by providing cooling to be carried out separately from heating.

Another purpose of the invention is to reduce production costs by using steam energy in the drying process.

Another purpose of the invention is to prevent product losses such as fragmentation and breaking of dried foods during the drying process carried out by using containers. In addition, manpower is used in loading and unloading food in container systems. Since trays are used instead of containers in the system of the invention, the need for manpower decreases in loading and unloading processes.

The structural and characteristic features and all advantages of the invention will be understood more clearly through the detailed explanation written with the following figures and references to these figures, and therefore assessment should be made by considering these figures and detailed explanation.

Brief Description of Drawings

Figure 1 : An overview of the drying system of the invention.

Figure 2 : A representative flow chart view of the drying system of the invention. Description of Part References

D. Drying System 1. Food supplying unit 10. Preheating unit

11. Fan

12. Resistance

13. Steam Valve

14. First band (the type of band is not written in order to extend the scope of protection.)

15. Preheating Unit Inlet Flap

20. Explosion Puffing unit

21. Magnetron

22. Second Vacuum Relief Valve 23. First Vacuum Valve

24. First Vacuum Unit

25. Second Band

26. Explosion Puffing Unit Inlet Flap 30. Drying Unit 31. Pleating Plate

22. Second Vacuum relief valve

33. Second Vacuum Valve

34. Second Vacuum Unit

35. Third Band

36. Drying Tunnel Inlet Flap 40. Cooling Unit

41. Third Vacuum Relief Valve

42. Third Vacuum Valve

43. Third Vacuum Unit

44. Fourth Band

45. Cooling Unit Inlet Flap

46. Cooling Plate

47. Cooling Unit Outlet Flap Detailed Description of the Invention

In this detailed description, the preferred embodiments of the drying system (D) of the invention are explained for a better understanding of the subject.

By means of the drying system (D), explosion puffing drying of foods such as fruits and vegetables is provided. The explosion puffing drying process that is used for production of dried crisp fruits and vegetables is realized by transferring the moisture content of the food into vapor form by creating rapid temperature and pressure difference and thereby drying by providing a porous structure. With reference to Figures 1 and 2, the drying system (D) of the invention; comprises food supplying unit (1), preheating unit (10), explosion puffing unit (20), drying unit (30) and cooling unit (40). In the drying system (D), the vacuum is used by combining the heat supplied by the resistance (12) and the steam. In the drying system (D), the foods are placed on the food supplying unit (1) and transferred to the preheating unit (10). The food supplying unit (1) carries the foods to be dried to the preheating unit (10), explosion puffing unit (20) and the drying unit (30). With reference to Figure 1 , due to the homogeneous heating (steam and conventional air) in the preheating unit (10), they are heated and carried to the explosion puffing unit (20).

Products having 16 - 24% humidity level are filled to the preheating unit (10) at a certain ratio on PP trays which are resistant to 105 degrees of temperature. These trays are pushed into the food supplying unit (1) and the preheating unit (10). The preheating unit inlet flap (15) is closed to provide a hermetic environment. The fan (11) connected with the preheating unit (10) is operated and air circulation is provided in the environment. After air circulation is provided, the resistance (12) is activated and the air is brought to a certain temperature. When the circulation temperature reaches a certain level, the steam valve (13) is opened and steam is fed to the system. Steam is passed through the resistance (12) in order to balance the temperature by mixing into the circulation air. Thereby, a drier air is obtained. Heat and humidity of the circulation air is controlled through heat and humidity measuring devices provided in the unit. When the humidity level of the circulation air rises, the steam valve (13) shut off and the relieve valve is opened. Thereby, the temperature of the products is raised to 75 degrees with a balanced and controlled hot air circulation. By balancing the humidity level of the products having humidity differences on the tray, they become ready for explosion puffing process. With the help of the first band (14), the trays are transferred to the explosion puffing unit (20).

After the tray enters the explosion puffing unit (20), the explosion puffing inlet flap (26) closes. The first vacuum unit (24) operates and the first vacuum valve (23) is opened after the line reaches the determined vacuum level, thereby reducing the pressure in the explosion puffing unit to 50 mBar, allowing the water in the product to evaporate quickly. The water content of the product trying to evacuate by turning into vapor in a very short period of time causes the product volume to expand. The heat supply required for the continuation of the explosion process is provided by the magnetron (21). It also operates in our preheated system to keep the steam heated products at a certain temperature during explosion puffing and vacuuming. The durability of magnetrons (21) is extended because magnetrons (21) will work less in this way.

Product temperature is monitored instantaneously by a sensor located in the explosion puffing unit (20). After the product temperature falls down to the required temperature of the process, a constant product temperature is maintained by operating the magnetron (21). Equal distribution of microwave rays over the products in the tray is achieved by the second band (25). The first vacuum valve (23) and magnetron (21) are turned off after it is understood that the explosion puffing process has been completed as a result of monitoring the products in the container and logarithmic calculations. By opening the second vacuum valve (33) and the second vacuum pump (34), the internal pressure of the drying unit (30) is equalized with the explosion puffing unit (20). By opening the drying unit inlet flap (36), the tray is carried onto the third band (35).

The trays filled with products are carried by means of the third band (35). With the second vacuum unit (34), the pressure value in the tunnel is maintained at 50 Mbar level. The energy required to vaporize the water remaining in the products is provided by heating plates (31).

The trays which completed the drying process are equalized with the internal pressure of the drying unit (30) by means of the internal pressure of the cooling tunnel (40), the third vacuum valve (42) and the third vacuum unit (43) to ensure passage to the cooling tunnel, which is the final stage of the process.

The trays are carried to the fourth band (44) by opening the cooling tunnel inlet flap (45). The products on the tray are cooled by means of the cooling plate (46). Finally, the internal pressure of the drying unit (30) is equalized with the atmospheric pressure by opening the first vacuum valve (22), the second vacuum valve (32) and the third vacuum relief valve (41) and the trays are carried outside by means of the fourth band (44) by opening the cooling tunnel outlet flaps (47).

The drying system (D) provides explosion puffing drying of foods within 35 - 40 temperature range or at lower temperatures. Thereby, the nutritional values of foods such as vitamins and minerals are preserved.

Claims

1. A drying system (D) intended to be used for explosion puffing drying of foods such as fruits and vegetables, comprising a food supplying unit (1) which allows the food to be carried to the area of explosion puffing and drying areas, characterized by further comprising;

- a preheating unit (10) which provides homogeneous heating of foods using steam and conventional air,

- an explosion puffing unit (20) comprising at least one magnetron (21), which is the microwave heating source providing heat for explosion puffing of foods, a second band (25) which allows homogenous distribution of the rays coming from the microwave heating source magnetron (21) over the foods by moving back and forth and a first vacuum unit (24) which provides the explosion puffing process to be carried out under vacuum,

- a drying unit (30) where the drying process is applied to the foods leaving the mentioned explosion puffing unit (20), comprising at least one heating plate (31) heated with steam energy, a third band (35) which allows homogenous distribution of the steam energy over the foods by moving back and forth and a second vacuum unit (34) which provides the drying process to be carried out under vacuum,

- a cooling unit (40) which provides cooling of the foods leaving the mentioned drying unit (30) dried and comprises a third vacuum unit (43) which prevents the dried foods to be effected by the moisture present in the environment by providing the mentioned cooling process to take place under vacuum.

2. The drying system (D) according to claim 1 , characterized by comprising an explosion puffing unit inlet flap (26) which allow the foods to enter the mentioned explosion puffing unit (20) and which prevent the vacuum maintained inside the mentioned explosion puffing unit (20) to leak outside.

3. The drying system (D) according to claim 1 , characterized by comprising a drying tunnel inlet flap (36) which allows the foods to leave the mentioned explosion puffing unit (20) and allows the foods to enter the mentioned drying unit (30), prevents the vacuum maintained inside the mentioned explosion puffing unit (20) and the mentioned drying unit (30) to leak outside.

4. The drying system (D) according to claim 1 , characterized by comprising a cooling unit outlet flap (47) which allows foods leaving the mentioned drying unit (30) to be transferred to the mentioned cooling unit and which prevents the vacuum maintained inside the mentioned drying unit (30) to leak outside.