JPS61195640A - Method of vacuum drying of fish - Google Patents

Abstract

PURPOSE:To dry ideally miscellaneous fishes by using a vacuum device of clean exhaust system, by reducing pressure of a closed container storing fishes successively by using a steam ejector, a water jet, and a booster ejector and heating them. CONSTITUTION:Fishes are stored in the closed container 1, the pressure of the container 1 is firstly reduced by using the steam ejector 9, the pressure of the container 1 is further reduced by using the water jet 12, finally the pres sure of the container 1 is reduced to <=30Torr degree of vacuum by the booster ejector 17, and fishes are dried under heating at 80-140 deg.C. Consequently, a vacuum device of clean exhaust system free from environmental pollution caused by treatment of waste oil and exhaust system is used and this drying method is suitable for drying especially miscellaneous fishes.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for drying fish, and more particularly to a method for drying fish, and more specifically, a method for drying fish that prevents environmental pollution caused by a vacuum exhaust system and that is suitable for drying small fish that have relatively low commercial value. Regarding drying method.

(Prior art) Conventionally, fish belonging to so-called minor fish such as flounder flounder and small sardines, which have low commercial value as fresh or dry products, are
The cold air drying method, which involves drying at a low temperature of about 40°C, is not profitable because it takes a long time to dry.On the other hand, if you try to dry it at a high temperature in a short time, it will result in a dried product with a thin, burnt appearance. It had completely lost its commercial value.

Therefore, a method was proposed to produce dry products by drying fish, especially small fish, under reduced pressure and heat, and a water jet pump was used to maintain the airtight container containing the fish under reduced pressure. .

However, when using a water jet pump, the water vapor pressure is low during the winter when the water temperature is low, so it is possible to maintain a sealed container containing fish at the desired degree of vacuum in a relatively short period of time. As the water temperature rises, the vapor pressure of the water increases, making it impossible or taking a long time to reach the desired degree of vacuum in the closed container containing the fish. Ta.

Another problem is that even once the desired degree of vacuum is reached, the degree of vacuum gradually decreases as the water temperature rises over time.

As described above, if the time required to reach the desired degree of vacuum becomes longer, it will take a longer time to dry the fish, and the freshness of the fish as dried food will naturally decrease.

Therefore, it has been extremely difficult to use water jets all year round.

In order to solve this problem, especially in the summer, we first use a rotary pump to
A method has been proposed and adopted in which a rotary pump and a water jet are used together to reach a certain level of vacuum, and then switch to a water jet to maintain the desired vacuum level.

However, the use of rotary pumps inevitably generates waste oil, which must be disposed of, and in addition, as fish drying sites are concentrated in coastal areas, there is a risk of contamination of seawater by waste oil. there were.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned conventional drawbacks, and uses a vacuum device with a clean exhaust system that does not cause any problems of waste oil treatment or environmental pollution due to the exhaust system, and is particularly suitable for drying small fish. The purpose of this invention is to provide a drying method.

[Structure of the invention]

A first aspect of the present invention that achieves the above object is to house fish in a sealed container, first reduce the pressure in the sealed container using a steam ejector, then further reduce the pressure in the sealed container using a water jet, and finally use a booster ejector to reduce the pressure in the sealed container. The method is characterized in that the sealed container is reduced in pressure to a degree of vacuum of 30 Torr or less, and then heated to 80 to 140°C to dry the fish.

Further, in the second invention, fish are housed in a sealed container, first the pressure is reduced in the sealed container using a steam ejector, and then the sealed container is heated for 30 minutes using a water jet.
After reducing the pressure to a vacuum level of Torr or less, 80 to 140℃
The method is characterized in that the fish is dried by heating.

Hereinafter, the present invention will be explained based on the steps shown in the drawings.

The vacuum chamber 1 is composed of a main body 2 and a door section 6.

A heating shelf 3 is housed in the main body 2, and this shelf 3
A tray 4 is placed on top of the tray.

Fish taken from the sea are lined up on this tray 4 and arranged on the shelves 3.

Next, the door portion 6 is closed and the vacuum chamber 1 is hermetically sealed.

Here, in the present invention, first, the steam ejector 9
Activate the switch. That is, the steam generated in the boiler 8 is guided to the steam ejector 9 via the superheater S, and the steam exiting the ejector 9 is condensed in the condenser 10 and sent to the boiler 8 again by the pump 11.

In this way, first, the inside of the vacuum chamber 1 is lowered from atmospheric pressure to -550
Lower the vacuum to -600mm.

Next, in the present invention, when the degree of vacuum reaches within this range, the valve 20 is closed, the valves 18 and 21 are opened, the water jet 12 is operated, and the steam ejector 9 is stopped, and the water jet 12 is activated. The inside of the vacuum chamber 1 is brought to a degree of vacuum of 580 mm to -750 mm.

The water discharged from the water jet 12 is transferred to a circulating water tank 13.
is stored in the cooling tower 15 by the pump 14.
After being sent to the water jet 1 and cooled, the water is sent to the circulating water tank 13 again, and the water jet 1 is again sent to the circulating water pump 16.
2.

Finally, in the present invention, the booster ejector is activated to reduce the inside of the vacuum chamber 1 to 30 Torr (-730 mm).
Hereinafter, the pressure is preferably reduced to a degree of vacuum of 20 to 10 Torr.

That is, the steam valves 19 and 19 are opened, the bypass valve 18 is closed, and the valve 22 is opened.

If the degree of vacuum is not lower than 30 Torr, the fish's belly and flesh will split, and the fish will have a mummified shape after drying.

When the degree of vacuum becomes 30 Torr or less, the heating medium inlet valve 5 is opened to introduce a heating medium, such as steam, into the heating tray 3 to heat the fish in the tray 4 on the tray.

Next, in the second invention, the inside of the vacuum chamber 1 is heated by the steam ejector 9 in the same way as in the first invention.
Create a vacuum of 0 mm to -600 mm. Next, the pressure inside the vacuum chamber 1 is reduced to 30 Torr or less, preferably 20 to 10 Torr, using the water jet 12 .

This second invention is effective when the water temperature is low in winter, for example when the water temperature is 20'C or less, and there is no need to use a booster ejector.

As described above, in the present invention, by using a steam ejector, a water jet, and a booster ejector in combination, or a steam ejector and a water jet in combination, it is possible to The fish should be exposed to the vacuum level as quickly as possible.

In conventional methods of vacuum drying fish, if the fish body is rapidly exposed to reduced pressure, internal organs may rupture, blood drips, the fish body warps, etc., so it is necessary to vacuum the fish body gradually.

Similarly, it was considered preferable to raise the temperature gradually.

In contrast, in the present invention, by using a steam ejector, a water jet, and a booster ejector in combination, or a steam ejector and a water jet in combination, vacuuming is performed as quickly as possible, completely contrary to the conventional vacuum drying method. , and preferably the temperature is raised quickly.

If the vacuum is gradually reduced to 30 Torr or less or the temperature is gradually raised, the dried product will become mummified as described above, or the fish will stick to the tray 4, making it difficult to peel off (8).

The heating temperature is usually 80 to 140"C, preferably 120 to 140"C.

If the heating temperature is lower than 80°C, softening of the fish bones and swelling of the fish meat will not occur, and if the heating temperature exceeds 140°C, it will become excessively dry and burnt, which is not preferable.

Under such vacuum and heating conditions, the fish body is dried and heated by radiant heat and heat transfer.

It should be noted that fish can be dried according to the present invention immediately after coming out of the sea, but depending on the type of fish, for example sardines, blood drips a lot, so after cooking, it is necessary to go through a process of running water for about 3 hours to remove blood. It is preferable to dry it afterwards.

The drying time is appropriately determined depending on the type of fish, and for example, for flounder, it is 2 to 3 hours.

Note that 7 is a drain for draining moisture and oil condensation from fish.

After drying is completed, the door 6 is opened, the tray 4 is taken out and left to cool, and dried fish products are obtained.

〔Effect of the invention〕

As described above, according to the present invention, the following effects can be achieved.

(a) In the present invention, the pressure of a sealed container containing fish is first reduced with a steam ejector, then further reduced with a water jet, finally reduced with a booster ejector or steam ejector, and then with a water jet to reduce the pressure to 30 Torr or less. Since the pressure is reduced, no waste oil is produced and a clean exhaust system can be constructed.

Conventionally, when a rotary pump is used in conjunction with a water jet, there is a risk of contaminating seawater with waste oil from fish drying factories, which are common in coastal areas.
Since the present invention provides a clean exhaust system, it is possible to completely eliminate the problem of seawater contamination caused by such waste oil.

(b) In the present invention, the steam ejector, automatic jet, and booster ejector are used in combination, so as in the case of using a water jet,
It is possible to completely eliminate the problem that it takes too long to reach a degree of vacuum of 30 Torr due to an increase in water temperature.

Furthermore, when the water temperature is low in winter, the degree of vacuum of 30 Torr or less can be similarly quickly reached by using a steam ejector and a water jet in combination.

In this way, the degree of vacuum of 30 Torr or less is quickly reached, thereby preventing deterioration of the freshness of the fish and making it possible to obtain dried products of excellent quality.

(c) Since it is dried at 80 to 140°C, the obtained dried product has no fishy odor or so-called raw fishiness.

Therefore, raw fish is suitable as a food for people who are afraid of fish.

(d) Since the drying temperature is as high as 80 to 140°C, the surface of the fish body after drying becomes a beautiful "candy-brown" color and emits a fragrant aroma.

(e) Because it is dried at high temperatures, the fish bones soften and
Since it is dried under a vacuum of less than Torr, it is possible to obtain a dried product in which the fish meat is in a swollen state, which cannot be obtained by conventional drying methods.

Therefore, if you grill it and eat it, you can eat the whole bone by softening the fish bone, and it is a whole food with a good balance of calcium and phosphorus in the bone, vitamin D in the internal organs, and protein in the fish meat. is obtained.

Kube) The puffing of the fish meat softens the texture and facilitates digestion.

(g) Since it is a high temperature vacuum dried product, a sterilized and hygienic dry product can be obtained.

(h) Therefore, the dry product obtained by the method of the present invention is
As mentioned above, it is not only suitable as a food for school lunches because it is rich in nutrients (but it can also be eaten as a snack food since it can be eaten whole), and can also be used as a flavored food such as sweets, sweet potatoes, etc. It can also be used as a secondary processed product.

Furthermore, it can be pulverized into powder and used as a filler, additive, or filler for foods containing sufficient calcium.

(S) Furthermore, the method of the present invention can be used to dry so-called high-grade fish that have conventionally been dried with cold air, but the method can also be used to dry small, worthless fish that have rarely been used for human consumption. This method is not only particularly effective as a method for drying small fish, but also prevents wastage of resources.

(v) Furthermore, since the method of the present invention employs a vacuum drying method, the energy loss is as small as about 2 to 3%, compared to about 50% in the conventional ventilation drying method. Since it is dried in a high-temperature vacuum, the drying time can be 2 to 3 hours, for example, for Japanese flounder.

This is significantly shorter than 10 hours or more for conventional ventilation drying methods and 6 hours or more for ordinary low-temperature drying methods, and can significantly reduce the running cost required for manufacturing dry products.

[Brief explanation of drawings]

The figure is a process diagram showing an example of the present invention. 1- Vacuum tank, 3- Shelf, 4-) Ray, 9- Steam ejector, 12- Water jet, 17- Booster ejector.

Claims (1)

[Claims] 1. Fish are housed in a sealed container, first the pressure is reduced in the sealed container using a steam ejector, then the pressure is further reduced in the sealed container using a water jet, and finally the pressure is reduced by a booster ejector. A method for vacuum drying fish, which comprises reducing the pressure of a sealed container to a degree of vacuum of 30 Torr or less, and then heating the container to 80 to 140°C to dry the fish. 2. Place the fish in an airtight container, first reduce the pressure in the airtight container using a steam ejector, and then add water.
A method for vacuum drying fish, which comprises reducing the pressure of the sealed container to a degree of vacuum of 30 Torr or less using a jet, and then heating the container to 80 to 140°C to dry the fish.