JPH0528583B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a vacuum frying method and apparatus for frying foods such as various vegetables, fruits, marine products, livestock products, or molded products thereof under reduced pressure. [Prior Art] When producing fried foods by frying foods such as various vegetables, fruits, marine products, livestock products, or molded products thereof, the above-mentioned foods are generally cut into appropriate sizes. A method is adopted in which the food is housed in a basket and the basket is immersed in heated oil in a frying tank under reduced pressure. However, for a while after starting flying, the food is heated under reduced pressure and suddenly releases a large amount of water vapor, and the rising force of this water vapor and the buoyancy of the food cause it to rise all at once and reach the lid. Since they are pressed with a strong force, they tend to stick to the lid or stick to each other and form lumps, which has a negative effect on the quality of the product. Therefore, in order to solve these problems, for example, we have developed a method of flying the Watsuguru frame that supports the raw material case by moving it up and down in oil, and a method of flying the food material by moving it up and down into oil or above the oil surface. A flying method has been proposed in which the oil is kept stationary in oil for a while after repeating this process for several minutes. However, in the former method, the raw material case is moved up and down while completely immersed in oil, so it is difficult to ensure that the food, which rises all at once due to large buoyancy, is dispersed and does not stick. This method has the disadvantage that it is extremely difficult, especially when a large amount of food is to be processed, and the latter method requires that the food be removed from the oil during frying. However, heating is performed intermittently, which not only reduces heating efficiency and increases frying time, but also causes the food to become fluffy and difficult to finish.Furthermore, the basket must be raised and lowered with large strokes. As a result, there was a problem that the raw materials were often damaged in the basket and the yield of the product was poor. [Problems to be Solved by the Invention] An object of the present invention is to provide a frying method and apparatus that can efficiently fry foods in a short period of time without forming lumps due to mutual adhesion. [Means for Solving the Problems] In order to solve the above problems, the frying method of the present invention provides a fully immersed state in which the entire basket containing food is immersed in heated oil in a depressurized frying tank, and a method in which only the upper part is immersed. The food in the basket is heated for a certain period of time while being moved up and down between a semi-immersed state where the food is exposed above the oil surface, and then the food is lifted above the oil to drain the oil. . The frying device also includes a frying tank for frying food stored in a basket under reduced pressure, a receiving frame for the basket disposed in the frying tank so as to be movable up and down by an elevating means, and a receiving frame that is raised and lowered via the cylinder. and a control device for controlling the receiving frame, and the control device controls the receiving frame to move the basket up and down between a fully immersed state in which the entire basket is immersed in oil and a semi-immersed state in which the upper part is exposed above the oil surface. It is characterized by being constructed as a product. [Example] Hereinafter, the present invention will be described in more detail with reference to the drawings. In FIG. 1, 1 is an open basket with an open top for storing foods to be flown, such as vegetables, fruits, seafood, livestock products, or molded products thereof; 2 is a basket that is stored in the basket 1; A frying tank 3 is a conveyor for feeding the basket 1 into the frying tank 2 and taking it out from the frying tank 2 through an opening 4 which can be freely opened and closed. The frying tank 2 is always filled with an appropriate amount of oil 8 from an oil tank 6 by an oil supply pump 7, and this oil 8 is heated to a predetermined temperature by a heating pipe 9 using steam as a heat source. In addition, a vacuum pump 13 is connected to the upper space of the frying tank 2 by a suction pipe 11 through a condenser 12 for separating water and air, so that the pressure can be reduced to a predetermined pressure by the vacuum pump 13. It's summery. Moisture condensed by cooling in the condenser 12 is collected in a recovery tank 15 through a recovery pipe 16 and sequentially discharged by a drain pump 17. Further, in the frying tank 2, a receiving frame 20 for supporting the basket 1 fed through the opening 4 is arranged such that it can be raised and lowered by being suspended from a support member 22 attached to the piston rod 21a of the cylinder 21. A lid body 23 for opening and closing the basket 1 supported by the receiving frame 20 is provided.
By being suspended from the support member 22, the receiving frame 2
The basket 1 can be raised and lowered in synchronization with the basket 1, and can be moved toward and away from the basket 1 by means of an opening/closing mechanism 24 on a support member 22. This opening/closing mechanism 24 may have any configuration as long as it can move the lid body 23 toward and away from the basket 1. The cylinder 21 is connected to a control device 25 including a solenoid valve and a pressure fluid source.
The basket 1 on the receiving frame 20 is controlled to move up and down between a fully immersed state in which the entire basket is immersed in oil and a semi-immersed state in which only the upper part is exposed above the oil surface. The basket 1 and the lid 23 are formed of a perforated plate such as a wire mesh or a perforated plate through which oil can flow, and at least the inner surface thereof has heat resistance and oil resistance, and is resistant to food adhesion. It is desirable to coat it with a synthetic resin that is difficult to wash, such as tetrafluoroethylene. Note that 26 in the figure is an oil drain port for draining the oil 8 in the frying tank 2. In the fryer having the above configuration, at the start of work, both the receiving frame 20 and the lid body 23 are in the first position.
It has risen to the solid line position in the figure and is waiting. In this state, when the basket 1 filled with food is transferred on the conveyor 3, sent into the frying tank 2 through the opening 4, and placed on the receiving frame 20, the opening/closing mechanism 24 is activated to open the lid. 23 descends,
The basket 1 is closed. Next, the opening 4 is hermetically closed, and the inside of the frying tank 2 is maintained at a predetermined pressure (for example,
After the pressure is reduced to 30 Torr, the cylinder 21 is controlled by the control device 25 according to a predetermined program, and the receiving frame 20 is moved up and down to perform flying. That is, first, the receiving frame 20, which has been waiting at the raised position shown in FIG. 2A, is lowered to the full immersion position where the basket 1 is completely immersed in oil, as shown in FIG. At this position, the food in the basket 1 is heated for a certain period of time. Subsequently, as shown in FIG. 2C, the receiving frame 20 is raised to a semi-immersed position where the upper part of the basket 1 is exposed above the oil surface, and after being heated for a certain period of time in this semi-immersed position, the receiving frame 20 is is again lowered to the full immersion position, and thereafter the food is heated for a predetermined time while the receiving frame 20 is repeatedly moved up and down between the full immersion position and the half immersion position. The number of times and the time interval at which the receiving frame 20 is moved up and down between the full immersion position and the half immersion position can be set as appropriate depending on the type of food to be flown, the amount of food to be filled into the basket, etc. From the start to the end of the flight (usually about 10 to 20 minutes), the vertical movement can be set to occur at equal intervals or at different intervals in stages. In this way, by heating the food with the basket 1 fully immersed at the beginning of the frying process, the entire food is heated evenly, eliminating uneven heating that would occur when heating the food in the partially immersed state. It never occurs. In addition, when heating in a semi-immersed state, a space is formed on the oil surface, so even if foods that have been heated to a certain extent and become easy to stick to float to the surface one after another, the basket 1
Convection occurs sequentially without being pressed against the lid body 23, and the food is automatically stirred, so that it is reliably prevented that these foods stick to the lid body 23 or stick to each other and form lumps. Ru. Next, when the heating is finished, the receiving frame 20 is placed in the first position.
It rises to the solid line position in the figure and moves up and down in small increments to remove oil from the food. When this is completed, the reduced pressure in the frying tank 2 is released, the lid body 23 is opened, and the opening 4 is opened. basket 1 is taken out. Here, the oil from the food can be removed by reducing the pressure inside the frying tank 2 to a higher vacuum state, or by transferring the basket 1 to a separate room where the pressure can be adjusted. Cooling of food can also be achieved by supplying it with cold air. The receiving frame 20 can also be configured so that a plurality of baskets 1 can be placed thereon at the same time. In this case, the lid body may be provided with one large piece that spans the plurality of baskets 1, or one lid body can be placed on each of the baskets 1. A plurality of independent lids are provided for each basket 1, and these lids are configured to be opened and closed synchronously. In the above embodiment, the basket 1 is transported into the frying tank 2 by the conveyor 3, but it goes without saying that the basket 1 may be transported manually. Further, a cylinder 21 is used as a means for raising and lowering the receiving frame 20.
is used, but other lifting means such as a motor can also be used. Therefore, when frying food raw materials as described above, the temperature of the raw materials before frying is close to room temperature, so the oil temperature in the frying tank should be adjusted to a temperature higher than the temperature suitable for frying the raw materials. ,
It is desirable to start flying in this state. This is because, when flying under reduced pressure as mentioned above, most of the moisture in the raw materials is evaporated within a few minutes after the start of frying, and the quality of the product is improved by promoting drying of the raw materials as quickly as possible. This is because it is important for achieving this. Therefore, it is desirable to adjust the oil temperature so that when a low-temperature raw material is immersed in the oil, the oil temperature does not drop below the frying temperature suitable for the raw material. Third
The figure illustrates changes in oil temperature, evaporation, and degree of vacuum during flying. Furthermore, in order to reduce the residual oil content in the product after frying, it is necessary not only to drain the oil sufficiently, but also to maintain the pressure in the tank as high as possible. In the present invention, in addition to controlling the oil temperature and degree of vacuum, program control such as the time interval of vertical movement of the basket during frying is carried out to target all food ingredients and achieve crunchy texture and porous texture. It becomes possible to manufacture products with texture, etc. Next, an experimental example of the present invention will be explained. Experimental example: Core an apple, cut it into quarters, and cut into chips with a thickness of 3 mm using a slicer. Next, it was placed in a soaking tank filled with a low molecular weight sugar solution adjusted to a sugar content of 40 Brix, and after being soaked for about 4 to 5 hours, it was sliced into honey and subjected to a flying process under the following conditions. That is, frying starts with the oil temperature in the frying tank at 120℃, the oil temperature during frying is kept below 100℃ on average (90 to 95℃), and the pressure condition is a vacuum degree of 20Torr.
I tried to keep the front and back. Then, it was moved up and down between the fully immersed state and the half immersed state at 1.5 minute intervals, and the flying was completed in 12 minutes. After draining the oil in a vacuum, it was taken out from the frying tank and slowly cooled to produce a product. In addition, as a comparative example, the basket was flown while being moved up and down between the fully immersed state in oil and the fully exposed state in vacuum (Comparative Example 1);
A product which was flown while fully immersed in oil (Comparative Example 2) was obtained and compared with the product according to the invention. The results are shown in Table 1. As can be seen from the results, the product according to the present invention did not feel oily, had good color and texture, had almost no breakage, and was fully satisfactory.

[Table] Experimental Example A pumpkin was sliced into approximately 4 cm square pieces and 2 mm thick, and after undergoing the same pretreatment as in the experimental example, a flying treatment was performed using the same device. During flying, the average oil temperature was 95°C, the pressure conditions were a vacuum level of 5 Torr, flying time was 12 minutes, and vertical movements were performed at 2 minute intervals. Further, as a comparative example, a product was obtained under the same conditions as in Comparative Examples 1 and 2 in the experimental example, and was compared with the product according to the present invention. The results are shown in Table 2. This result shows that the product according to the present invention has good color and flavor, and has a particularly soft texture.

[Table] *1 Soft feel
*2 Experimental example showing firmness Beef was sliced into pieces approximately 5 mm thick, 5 cm wide, and 10 cm long, and seasoned by immersing them in a sauce mainly composed of soy oil, spices, and sugar. The seasoned meat pieces were then subjected to a frying process using the apparatus of the experimental example. At that time, the oil was processed at high oil temperatures to preserve the flavor of the ingredients as much as possible. The conditions at that time were
The average oil temperature during flying was 120°C, the pressure conditions were a vacuum level of 20 Torr, a flying time of 10 minutes, and a vertical movement interval of 1 minute. The results are shown in Table 3. As can be seen, a porous product with good taste was obtained.

[Table] [Effects of the Invention] As detailed above, according to the present invention, the food is heated while the basket containing the food is moved up and down between the fully immersed state and the partially immersed state. Therefore, by heating the whole food evenly in the fully immersed state, and then in the partially immersed state, the space formed at the top of the basket promotes convection of the food, and it heats up quickly. It is possible to reliably prevent the floating food from being pressed against the lid and adhering to the lid, or from adhering to each other and forming lumps, thereby obtaining a fried food that is plump and has an excellent texture. be able to. In particular, with the conventional method of moving the basket up and down in oil while completely immersed, it is difficult to reliably spread the food that rises all at once due to large buoyancy; If the amplitude is increased or the speed is increased, it is inevitable that the product will have more cracks and the yield will decrease.
In addition, with the method of placing the basket in oil or taking it out above the oil surface, the food that is being heated is temporarily removed from the oil, which results in intermittent heating, which reduces heating efficiency and increases frying time. In addition, there are disadvantages such as the food being difficult to finish and being more likely to break the raw materials in the basket. By flying while moving, such conventional problems can be reliably solved.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway configuration diagram showing an embodiment of a vacuum fryer according to the present invention, Figs. 2 A to C are explanatory diagrams of the frying process, and Fig. 3 shows oil temperature, evaporation, and temperature during frying. FIG. 3 is a diagram illustrating a state of change in the degree of vacuum. 1...Basket, 2...Fry tank, 8...
Oil, 20... Receiving frame, 21... Cylinder, 25...
Control device.

Claims (1)

[Scope of Claims] 1. A basket containing food is first heated for a certain period of time in a fully immersed state in heated oil in a frying tank under reduced pressure, and then the upper part is partially immersed in the oil. The basket is heated for a certain period of time in an exposed semi-immersed state, and then heat-treated for a certain period of time while being moved up and down between the fully immersed position and the half-immersed position, and then the basket is lifted above the oil to drain the oil. Features a reduced pressure frying method. 2. A frying tank for frying food stored in a basket under reduced pressure, a receiving frame for the basket arranged in the frying tank so as to be freely raised and lowered by a lifting means, and a control device for controlling the raising and lowering of the receiving frame via the cylinder. The control device controls the receiving frame to move the basket up and down between a fully immersed state in which the entire basket is immersed in oil and a semi-immersed state in which the upper part is partially exposed above the oil surface. A vacuum frying device characterized by comprising: