JPH01153035A - Production of dried onion chip - Google Patents

Abstract

PURPOSE:To provide the subject chips reduced in the dry thinness thereof, having a crispy texture and useful as a healthy food, by frying an onion with an oil, expanding the fried onion and drying the expanded onion under reduced pressure. CONSTITUTION:The objective chips are provided by frying an onion with an oil, expanding the fried onion and drying the expanded onion under reduced pressure. When the onion is fried, the frying is preferably continued until the weight of the oil-attached onion after fried becomes 61-100% of that of the onion before fried. The expanding is preferably performed by treating the fried onion with reduced pressures at a rate sufficient to expand the onion and reducing the pressure from ordinary pressure to a pressure of <=5,000 pascal within 1sec. The drying under the reduced pressure is further preferably carried out by holding the expanded onion under a pressure of <=500 pascal for 10-30sec, freezing the onion and subsequently subjecting the frozen onion to a heating treatment so as to raise the temperature of the frozen onion to 30-80 deg.C under a reduced pressure degree of 10-100 pascal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of industrial application] The invention relates to a method for producing dried onion chips, and more particularly to a method for producing dried onion chips having a crispy texture.

[Conventional technology] Recently, vegetables, fruits, etc. are used as raw materials for health-conscious foods.
There is an increasing demand for dried chips that sufficiently retain the flavor and color of the raw materials. One of the methods for manufacturing such dry chips is the vacuum swelling drying method (Japanese Patent Application Laid-Open No. 1983-1999-1).
No. 159739).

This method involves the use of one or more types of foods selected from the group consisting of vegetables, fruits, grains, beans, solid substances such as dough products based on cereals, or solid substances obtained by processing and cooking these solid substances. The food is subjected to rapid depressurization at a rate sufficient to cause the food to swell and to the extent that the water in the food freezes, and after the water in the food freezes, it is heated and dried, and then returned to normal pressure. ``Method for manufacturing distinctive snack foods.'' The dried chips obtained by this method have a swollen structure, that is, a porous structure, a -II crispy texture (crunchy and chewy texture), and less dryness.

The present inventors have developed dried chips made from various vegetables and fruits using the vacuum swelling drying method described above.
As one of these, we attempted to produce dried onion chips using onions as a raw material.

[Problems to be Solved by the Invention] However, if onions are simply subjected to the vacuum swelling drying treatment described in the above-mentioned publication, the dried onion chips obtained will have less dryness, but the texture will be too soft. There was a problem that the food lacked the crispy texture desired for snack foods.

Therefore, as a result of intensive research in order to obtain dried onion chips with a crispy texture using the vacuum swelling drying process, the present inventors found that by performing frying in oil as a pretreatment prior to performing the vacuum swelling drying process, It was found that dried onion chips having a crispy texture can be obtained.

[Means for Solving the Problems] The present invention includes (a) a step of frying onions with oil, (b) a step of swelling the fried onions, and (c) a step of drying the III-formed onions under reduced pressure. This invention relates to a method for producing dried onion chips.

The present invention will be explained in detail below.

First, the invention! Onions are stir-fried with oil. In the present invention, this treatment is the most important and allows dry onion chips with a crispy texture to be obtained. The weight of the onion with oil attached after frying in oil is 61-100% of the weight of the onion alone (not including the weight of oil) before frying, preferably 80-9%.
It is appropriate to set the amount to 5%. If it is below the above range, the structure of the onion will collapse and it will be difficult to maintain its shape, and if it exceeds the above range, the resulting dried onion chips will tend to have a soft texture and lack crispness.

Also, the amount of oil used is 2 to 10 g per 100 g of onions.
, preferably 3 to 6 g. Also,
The type of oil that can be used is not particularly limited as long as it is an edible oil, but examples include corn oil, palm kernel oil, soybean oil, rapeseed oil,
Examples include vegetable oils such as sesame oil, rice oil, safflower oil, coconut oil, cacao oil, sunflower oil, and cottonseed oil, and animal fats and oils such as butter, het, and lard.

Note that it is preferable to cut the onion into appropriate shapes before frying. Although the cutting method is not particularly limited, for example, the fL is cut into a scale shape or a ring shape by comb cutting or round cutting, and then each fL is further cut into several small pieces. The size of the pieces is not particularly limited, but in order to be eaten as a snack food and to dry the whole piece uniformly, it is preferable to use onions whose bulbs have a thickness of 3 to 8 mm. If it exceeds the length, the length from the cut surface to the opposite cut surface is 8 or less, preferably 3 to 3.
It is desirable to cut it to 8 mm.

Furthermore, the cut onions are preferably soaked in water. By exposing to water, the harsh taste in the dried onion chips obtained can be reduced. The long exposure is suitably carried out in running water at 5 to 25°C for 10 to 60 minutes, preferably 30 to 60 minutes.

Next, it is desirable to drain the onions that have been fried in oil. This not only makes it possible to shorten the time for the subsequent heat drying treatment under reduced pressure, but also prevents oil stains from occurring in the resulting dried onion chips and maintains good color tone of the onion chips. Draining can be done by soaking the fried onions in water or by placing the fried onions in a colander or the like and pouring water over them. In this case, the temperature of the water used is not particularly limited, and is preferably 20 to 90°C, preferably 40 to 90°C.
A suitable temperature is 60°C, and a suitable time is 2 to 60 seconds. The amount of water used is 5 per 100g of fried onions.
It is appropriate to set it as 00-10100O.

The onions fried in oil are preferably subjected to temperature control treatment with or without blanching. This temperature control process equalizes the temperature of the onions fried in oil.
Specifically, the temperature of the onion is adjusted to about 30 to 80°C, preferably about 40 to 60°C. The treatment time varies depending on the method, but approximately 1 to 30 minutes is appropriate. As the temperature control treatment means, there are methods such as placing the onion in an appropriate bag and then placing it in a constant temperature bath at a predetermined temperature, and placing the onion in an appropriate bag and then immersing it in running water. The latter is preferred because the processing time is short, about 1 minute to about 10 minutes. Also, by using running water, temperature control and wood passing can be done at the same time.

The fried onions are then puffed with or without appropriate pretreatment. Puffing of onions is carried out by subjecting the onions to a reduced pressure treatment at a rate sufficient to cause the onions to swell. When a food product is placed under reduced pressure, the boiling point of water is lowered, thereby causing a phenomenon of transpiration of water, especially free water, in the food product.

The food puffs up due to the rapid transpiration phenomenon occurring in a short period of time. Therefore, in the present invention, the onion is subjected to the reduced pressure treatment at a rate sufficient to rapidly evaporate the moisture in the onion in a short period of time. The phenomenon of puffing due to water evaporation varies depending on the type of food, and therefore the rate sufficient for puffing to occur also varies depending on the type of food. In the present invention, the pressure reduction treatment for swelling is performed by reducing the pressure around the fried onions from normal pressure to 5,000 yen.
This can be carried out by rapidly reducing the pressure to below Pascals, preferably below 3000 Pascals, within 1 second, preferably within 0.5 seconds.

In the present invention, the puffed onion is then subjected to vacuum drying. The drying under reduced pressure is preferably carried out by bringing the swollen onion into a frozen state (freezing treatment) and then heating it (heating drying treatment).

The freezing treatment is performed by freezing the swollen onions at a temperature of 10 to 500 Pascals, preferably 10 to 200 Pascals, and more preferably 100 Pascals.
This can be carried out by holding under a reduced pressure of ~200 Pascals for 10 seconds to 30 minutes, preferably 5 to 10 minutes. The freezing treatment is preferably carried out subsequent to the swelling process, and is suitably carried out within 5 minutes, preferably within 3 minutes, and more preferably within 1 minute after the completion of the swelling process. By performing the freezing treatment under the conditions described above, onions can be brought to an appropriate frozen state while maintaining their expanded state.

The frozen onions are heated and dried under a state where the degree of vacuum is further lowered than the freezing treatment conditions. By further lowering the degree of vacuum during the heat drying process, it is possible to dry without drying while maintaining appropriate internal freezing.

The degree of reduced pressure during the heat drying treatment is preferably about 10 to 100 Pascals.

Incidentally, by setting the degree of pressure reduction for swelling to 10 to 100 Pascal, swelling, freezing, and heating drying can be performed in parallel. If the degree of vacuum is less than 10 Pascals, the dried onion chips tend to lack crispy texture and have a soft texture; on the other hand, if the degree of vacuum is more than 100 Pascals, the chips tend to be dry and have a very soft texture. Dried onion chips tend to have a hard texture. The heating temperature is preferably such that the onion temperature is approximately 30 to 80°C, preferably 50 to 70°C. In addition, the drying time is such that the moisture content of the final product is about 5% by weight or less, preferably 1% by weight or less.
Heat drying is generally carried out for 1 to 10 hours until the content is ~3% by weight. The heating means is not particularly limited, but radiant heating such as infrared rays or microwave heating is preferable.

After the heating and drying process is completed, the pressure is returned to normal, and the obtained onion is transferred to the next process such as the packaging process.

Next, a specific apparatus that can be used in carrying out the present invention will be explained based on FIG. Reference numeral 1 indicates a drying chamber, and inside the drying chamber 1 there is provided a shelf 2 on which a plate 18 on which the processed material A is placed is placed. Heaters 3.4 are installed below and above the shelf 2. A cold trap 6 is connected to the side wall of the drying chamber 1 via a pipe 5, and the cold trap 6 is connected to a vacuum pump 8 via a pipe 7. On the other hand, the pipe 5.7 is provided with a solenoid valve 9.10, and a valve 9.10 of the pipe 5 is provided.
Reservoir tank 1 is connected before and after via pipe LL12.
3 is connected. The pipes 11.12 are each provided with a valve 14.15. After the drying process, an air supply pipe 16 for returning the drying chamber 1 to normal pressure is installed on the top surface of the drying chamber 1, and the air supply pipe 16 is provided with a needle valve 17.

The swelling and drying process using the above-mentioned apparatus is carried out, for example, as follows. First, the cold trap 6 is activated to cool the inside of the cold trap 6. On the other hand, after the onions that have been pretreated as described above are placed on the shelf 2 in the drying chamber 1, the lid is closed. Then close valve 9.14 and close valve 1.
0,15 is opened and the vacuum pump 8 is operated to set the reservoir tank 13 to 10 to 4000 Pascal. In the above state, the valve 14 is opened and the pressure inside the drying chamber 1 is reduced to 1000 to 5000 Pascals in a short time (within 1 second). Next, the valves 14 and 15 are closed, and the valve 9 is opened to further lower the degree of vacuum in the drying chamber 1 to 100 to 500 Pascal, and the degree of vacuum is maintained within the above range for a predetermined period of time. Next, the degree of vacuum in the drying chamber 1 is further lowered to 10 to 100 Pascals, and the heater 3.4 is turned on to dry at a predetermined temperature for a predetermined time. Then heater 3.4
After closing the valve 9.1o, the vacuum pump 8 is stopped and the valve 17 is gradually opened to return the inside of the drying chamber 1 to normal pressure. Then release the lid and get dried onion chips.

The present invention will be explained in more detail below with reference to Examples.

Example 1 An onion (150 g) was cut into wedges (8 equal parts), then separated by scales, and then each was further cut into several small pieces (the thickness of the scales was up to 4 cm). Next, the onion was exposed to water at 15° C. for 30 minutes. 100 g of the obtained onion was stir-fried with 4 g of corn salad oil for 15 minutes to obtain about 96 g of onion, which was placed in a bag and soaked in running water at 40° C. for 1 minute. After soaking in running water, place the onions on a tray,
It was placed in the drying chamber of the apparatus described above. Then, inside the drying chamber,
The pressure is reduced from normal pressure to 2000 Pascal within seconds, and then the degree of vacuum in the drying chamber is reduced to 500 Pascal within 1 minute after the pressure reduction.
The pressure was lowered to Pascal, and the pressure was further left at that reduced pressure for 3 minutes. Next, the degree of vacuum was further gradually lowered to 40 Pascals, and the onions were dried by heating for 4 hours with a heater so that the temperature of the onions did not exceed 50° C. to obtain dried onion chips.

The obtained dried onion chips had little dryness and a crispy texture.

Example 2 Dried onion chips were obtained in the same manner as in Example 1, except that after oil sanding, the chips were immersed in running water at 40° C. for 10 seconds to pass through the water. The obtained dried onion chips had a crispy texture. Further, the oil stain was less than that of Example 1, and the color tone was also brighter than that of Example 1.

Comparative Example 1 Dried onion chips were obtained in the same manner as in Example 1 except that oil sanding was not performed. The obtained dried onion chips are
Although there was less dry yaw, it lacked the soft and crispy texture of marshmallows.

Comparative Example 2 Dried onion chips were obtained in the same manner as in Example 1, except that the boiling process 1 was performed at 95° C. for 3 minutes instead of using oil sand. The obtained dried onion chips had little dryness. Although the texture was slightly better than that of Comparative Example 1, it was still marshmallow-like and soft and crispy, lacking in appetite.

[Effects of the Invention] According to the present invention, by frying in oil as a pretreatment when subjecting onions to a vacuum swelling drying process, dried onion chips not only have less dryness but also have a crispy texture can be obtained. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a vacuum drying apparatus that can be used in carrying out the present invention. ' Figure 1

Claims (8)

[Claims] (1) (a) The process of frying onions with oil, (b) a step of puffing the fried onions, and (c) Step of drying the swollen onions under reduced pressure A method for producing dried onion chips. (2) The manufacturing method according to claim 1, wherein the onion is fried until the weight of the onion with oil attached after frying becomes 61 to 100% of the weight of the onion before frying. (3) The manufacturing method according to claim 1, wherein the swelling is carried out by subjecting the onion to a reduced pressure treatment at a rate sufficient to cause the onion to swell. (4) The manufacturing method according to claim 3, wherein the pressure reduction treatment is performed by reducing the pressure from normal pressure to 5000 Pascal or less within 1 second. (5) The production method according to claim 1, wherein the drying under reduced pressure is carried out by freezing the swollen onion under reduced pressure and heating it. (6) The production method according to claim 5, wherein the freezing is carried out by reducing the pressure of the swollen onion to 500 Pascal or less and maintaining the reduced pressure for 10 seconds to 30 minutes. (7) The manufacturing method according to claim 5, wherein the freezing treatment is started within 5 minutes after swelling. (8) The production method according to claim 5, wherein the heating after freezing is performed such that the temperature of the frozen onion becomes 30 to 80°C at a degree of vacuum of 10 to 100 Pascals.