JPH0242933A - Method for drying onion - Google Patents

Abstract

PURPOSE:To efficiently recover a dried onion in a white state by dehydrating moisture of finely cut small pieces, then passing the small pieces between a pair of heated drums having the same diameter, hot-pressing the small pieces and peeling the hot-pressed small pieces from the drums. CONSTITUTION:Root and neck parts of an onion are cut and browned exodermises are removed. The resultant onion is then finely cut to 3-5mm size with a chopper, etc., and dehydrated. The obtained raw material is subsequently charged from a hopper 3 into a dryer 2 with a conveyor 1. Steam is fed from a boiler 8 through a pipe 11 into the interior of drums 5 in the dryer 2 and the drum surface temperature is preferably heated to 160-165 deg.C. The raw material small pieces finely cut between the pair of heated drums are hot-pressed, thermally adhered to the drum surfaces, rotated, then scraped off with scrapers 19 and collected into containers 6 to afford the objective dried onion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for drying onions into flakes having a color close to white.

[Conventional technology]

Various methods have been tried in the past for cutting onions and other foods into small pieces and drying them.

For example, the technology described in Japanese Patent Publication No. 59-51254 is to bring grain powder into The slurry is spread between the drum and the rollers, heated and dried on the drum, and the dried grains are scraped off with a scraper.

[Problem to be solved by the invention]

As mentioned above, methods for drying various foods have been used in the past, but there is a problem in that when onions are dried using the conventional methods, they change color and turn brown, resulting in a loss of commercial value.

Furthermore, since the technique described in the above-mentioned Japanese Patent Publication No. 59-51254 is to feed grain between one large-diameter heated rotating drum and a small-diameter roller that does not have a heating means,
Grain is heated and dried by only one drum. For this reason, there is a problem that when drying small pieces, the drying effect is not very good.

In view of the problems of the conventional methods as described above, it is an object of the present invention to provide a highly efficient drying method that allows drying in a white state.

[Means to solve the problem]

In order to achieve the above object, this invention cuts the root and neck of onion to remove the browned outer skin,
A method of compressing and dehydrating small pieces of onion that have been shredded into ~5m square pieces to 30-35% of the weight, putting this between a pair of drums heated to an appropriate temperature, heating and pressurizing it, drying it, and then peeling it off from a roller and collecting it. It provides:

〔Example〕

The drawing shows an example of an apparatus for carrying out the method of the present invention, in which 1 is a belt conveyor for feeding raw materials, and 2 is a dryer.

The raw material, the onion, is cut by hand to remove the root and neck.
After removing the outer skin that has turned brown, it is dehydrated and chopped into 3 to 5 inch pieces using a chopper or the like.

The shredded and dehydrated raw material is fed into a hopper 3 of a conveyor 1, and fed into a dryer 2 through a chute 4 at its tip.

The dryer 2 is provided with a pair of hollow drums 5 rotating in the direction of the arrow and a pair of dried product recovery containers 6 in a drying chamber 7.

8 is a boiler, and the steam generated in this boiler 8 is passed through valve 9.1.
A distributor 12 in the drying chamber 7 is supplied via a steam supply pipe 11 with 0.

A steam distribution pipe 15 having a valve 14 is connected to the distributor 12, and each pipe 15 is connected to a hollow rotating shaft of each drum 5 via a running joint (not shown), so that steam is supplied to the drum 5. By blowing, the surface temperature of the drum 5 is heated to about 160° C. to 165° C., and the drain generated inside the drum 5 is taken out by a drain vibrator 17 and sent to a drain collector 18.

Since a scraper 19 is provided on the outside of each of the drums 5, the drum 5 can be moved from the chute 4 as described above.
The raw materials introduced in between are pressurized by passing between the drums 5,
It is thermally adhered to the surface of the drum 5, completes drying within one rotation, is scraped off by the scraper 19, and falls into the container 6.

The raw materials collected in the container 6 as described above are taken out together with the container 6 to be used as a product, or are further led to a flash dryer (not shown) for secondary drying.

The drain recovery device 18 exchanges heat with the water supplied from the water supply pipe 20 in a heat exchanger 21, and exchanges heat with the exhaust gas of the boiler 8 through the water supply preheater 23 attached to the boiler 8 using the pump 22 together with the supplied water. Water is supplied to 8.

Note that the spacing between the respective bearings of both hollow drums 5 can be freely adjusted, and by adjusting the spacing between the bearings, the gap between the drums 5 can be adjusted, and the vN node such as the rotation speed of the drum 5 can be adjusted. The moisture content (dry state) of the product is adjusted by

The data of the examples are shown below.

Surface temperature of drum 5 160°C Number of rotations of drum 5 4 PPM Diameter of drum 5 800 M Pressure applied to raw material by drum 5 150 kg/c Finely chopped onion 11.0 kg fruit juice
6.7 kg dehydrated onion 3.
8 kg dried flakes Yield: 6.36% for 0.7 kg shredded onions [Effects] As described above, this invention cuts the roots and necks of onions, removes the browned outer skin, and chops them with a chopper etc. 5. Small pieces cut into squares are dehydrated to an appropriate level of moisture, placed between a pair of rollers heated to an appropriate temperature, heated and dried, and then peeled off from the rollers and collected. The small pieces are sandwiched between a pair of drums and pressure is applied to squeeze out the juice, and then the pieces are heated and dried by the surface temperature of the drums while being adhered to the surface of the drums.
Drying takes place in a very short time. Therefore, since the small pieces are dried before turning brown and drying in an almost white state, products with high commercial value can be obtained, and the drying time is also short.

[Brief explanation of the drawing]

The drawing is a longitudinally sectional front view showing an example of an apparatus for carrying out the method of the present invention. 1... Belt conveyor for raw material input, 2...
... Dryer, 5 ... Hollow drum, 6 ... Dry product collection container, 7 ... Drying room, 8 ... Boiler, 1 ... ...Steam supply pipe.

Claims (1)

[Claims] (1) Cut the root and neck of the onion, remove the browned outer skin, cut into small pieces with a chopper etc. into 3-5 mm square pieces, dehydrate them to an appropriate moisture content, and place them between a pair of drums of the same diameter heated to an appropriate temperature. A method for drying onions, which is characterized in that the onions are thrown in, dried by heating and pressurizing, and then peeled off from a drum and recovered.