JPS61115438A - Vacuum drying of fish - Google Patents

Abstract

PURPOSE:To prepare a dried food having soft and agreeable palatability and high commercial value from small fish which hitherto have been discarded, and to utilize the small fish as food, by putting fish in a closed vessel and carrying out vacuum thermal drying under specific condition. CONSTITUTION:Fish is put into a closed vessel, evacuated to <=30Torr, preferably 20-10Torr, and heated at 80-140 deg.C to effect the vacuum-drying of the fish. Concretely, the drying is carried out by using a drying apparatus consisting of a vacuum chamber 1 containing heating shelves 3 and a water-jet 9 for evacuation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vacuum drying method for fish, and more particularly to a vacuum drying method suitable for small fish that have relatively low commercial value.

[Prior art]

Conventionally, when producing dried fish products (dried fish), a cold air drying method, that is, a method of drying at a low temperature of about 20 to 40° C., has generally been adopted.

This is because drying at low temperatures prevents deformation of the fish body shape and deterioration of body color, thereby increasing the commercial value of the dried product.

It is true that in the past, the commercial value of dried products was determined by their shape and color.

However, this low-temperature drying method is suitable for drying high-grade fish, and is not suitable for drying fish that belong to so-called minor fish such as flounder flounder and small sardines, which have relatively low commercial value as fresh or dried products. It is not profitable to dry the product by drying it at a low temperature for a long time.On the other hand, if you try to dry it at a high temperature in a short time, the product will become thin and burnt, and the product value will be completely lost. Ta.

In particular, when small fish with hard bones such as flounder and small sardines are dried at a high temperature of 40 to 50°C, the bones remain hard and the fleshy part becomes hard.

Therefore, these small fish are not used as fresh fish or dry products, but are either disposed of or, at most, used as feed for farmed fish such as yellowtail.

The current situation is that even if you put in a net, all the fish that come up are small fish (such cases are becoming more common in recent years), and the boat is not able to turn it into oil.

This situation can only be described as a waste of resources in a double sense.

[Purpose of the invention]

The present invention was made in view of the current situation, and it is possible to utilize small fish, which were conventionally only discarded or used as feed, as side foods, snack foods, or flavored secondary processed products. The purpose is to

[Structure of the invention]

The present invention achieves the above object by storing fish in a closed container, reducing the pressure to a vacuum level of 30 Torr or less, and then
The method is characterized in that the fish is dried by heating to 40°C.

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

FIG. 1 shows an example of a drying apparatus used in the present invention, and a vacuum chamber 1 is composed of a main body 2 and a door section 6. As shown in FIG.

A heating shelf 3 is provided within the main body 2, and a tray 4 is placed on the heating shelf 3.

Fish brought up from the sea are lined up on this tray 4 and placed on the shelves 3.

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

First, the water depressor 9 is operated to reduce the pressure in the vacuum chamber 1 to 30 Torr or less, preferably 20 to 10 Torr.

If the degree of vacuum does not reach 30 Torr or less, the fish's belly and flesh will split, and the body shape after drying will become mummified. After the degree of vacuum in the vacuum tank 1 reaches 33 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 vacuum tank 1.

The heating temperature is usually 80 to 140°C, preferably 120 to 140°C. If the heating temperature is lower than 80℃, the fish bones will not soften and the fish meat will not puff up.
If the temperature exceeds 0°C, it becomes over-dry and looks burnt, which is not desirable.

Furthermore, in the present invention, once the fish are housed in the vacuum tank 1, it is preferable to maintain the above vacuum level as quickly as possible.

In other words, in the conventional method of drying fish under reduced pressure, if the fish body is rapidly exposed to reduced pressure, internal organs may rupture, blood drips, the fish body warps, etc., so it has been necessary to gradually vacuum the fish body. .

Similarly, it was considered preferable to gradually raise the temperature. On the other hand, in the present invention, rapid evacuation and heating are employed, completely contrary to the conventional vacuum drying method.

Gradually reduce the vacuum to 30 Torr or less, or gradually reduce the pressure to 80 Torr.
If the temperature is raised to ~140°C, the dry product will be mummified as described above, or the fish will stick to the tray 4, making it difficult to peel off.

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

Although fish can be dried according to the present invention immediately after coming out of the sea, some types of fish, such as sardines, have severe blood dripping. It is preferable to dry it after aging.

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

Discharged water from the water jet 9 is stored in a circulating water tank 10, sent to a clay ring tower 12 by a circulating water pump 11 to be cooled, and then sent to the circulating water tank 10 again. Supplied to Soto 9.

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

After drying, the door 6 is opened, the tray 4 is taken out, and the dried fish product is obtained by leaving it to cool.

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

(a) Since it is dried at a temperature of 80 to 140°C, the resulting dried product has no fishy odor or so-called raw fishiness. Therefore, for these reasons, it is suitable as a food for people who are afraid of fish.

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

(c) Because the fish bones are dried at high temperatures, they become soft and
Since it is dried under a vacuum of 0 Torr or less, a dry product with expanded fish meat, which cannot be obtained by conventional drying methods, can be obtained. Therefore, when grilled and eaten, the bones of the fish soften and can be eaten whole, providing a good balance of calcium and phosphorus in the bones, vitamin D in the internal organs, and protein in the fish meat. Food is obtained.

(d) The puffing of fish meat makes the texture soft and facilitates digestion.

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

(F) Therefore, the dry product obtained by the method of the present invention is not only suitable as a school lunch food because it is rich in nutrients as described above, but also can be used as a snack food because it can be eaten whole. It can also be used as a flavored secondary processed product such as ``ame-daki'' or ``amirin-zuke''.

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

(g) Furthermore, the method of the present invention can be applied to so-called high-grade fish that have conventionally been dried with cold air, but the method can also be applied to the above-mentioned, worthless small 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.

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

This is because the conventional ventilation drying method takes more than 10 hours.
i Compared to the 6 hours or more required by ordinary low-temperature vacuum drying methods, the drying time is significantly shorter, and the running cost required for producing dry products can be significantly reduced.

Examples of the present invention will be described below.

〔Example〕

After taking the flatfish out of the sea, they were washed with water, placed on a tray on the heating shelf in the vacuum chamber shown in Figure 1, and sealed, first checking that the degree of vacuum in the chamber was below 30 Torr. After that, 85°C warm water was circulated through the heating tray to heat the fish. Figure 2 shows the relationship between the degree of vacuum in the tank, the temperature, and the temperature of the fish body, and the drying time.

Drying was completed in 2.5 hours (150 minutes), and a dried product with softened fish bones and puffed fish meat was obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing an outline of a drying apparatus used in the present invention, and FIG. 2 is a diagram showing the relationship between drying temperature, degree of vacuum, and drying time. ■...Vacuum chamber, 3...Heating shelf, 4...Tray.

Claims (1)

[Claims] A method for vacuum drying fish, which comprises storing fish in a closed container, reducing the pressure to a degree of vacuum of 30 Torr or less, and then heating the fish to 80 to 140°C to dry the fish.