JPS635049B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method of heat treating raw fish in the production of fish meal. More specifically, the present invention relates to a heat treatment method for steaming raw fish in a fish meal manufacturing process.

(Conventional technology) Fatshu meal production involves boiling (heat treatment),
By rationally combining processes such as squeezing, drying, and crushing,
This is a fish processing method that efficiently turns fish into a solid powder. The heat treatment in the cutter during the production of fish meal is an important process in order to denature the proteins of the raw fish and obtain high quality fish meal at a high yield.

Conventionally, the heat treatment in this cooker has generally been boiling mainly using indirect heating, and direct injection of steam (also called live steam) has been used as an auxiliary means. For example, as shown in FIG. 2, a circular casing 10 containing a screw feeder 101
While putting the raw material fish W into the casing 10
2 and the jacket 1 of the screw feeder 101
Steam is passed through 03 and 104, respectively, to indirectly heat and boil the raw material fish while transporting it. Steam is injected directly into the front half of the casing in order to compensate for the drop in heat near the input port for raw fish, where the balance between heat load and heat supply is greatly disrupted.

(Problems to be Solved by the Invention) However, direct injection of steam generates drainage within the casing 102, which is undesirable because it is contained in the raw fish or mixed into the broth, causing an unnecessary load on other processes; This is necessary because the accumulation of condensate lowers the temperature of the heat transfer surface and the inner wall surface of the casing, reducing the capacity of the cutter, and furthermore, the boiling collision of the condensate destroys the surface structure of the raw fish and causes the extract, etc. to flow out. It is desirable to keep it to a minimum.

Therefore, in order to suppress the amount of direct steam injection as much as possible, a method is used to raise the overall heating temperature, but since it is indirect heating, an uneven temperature distribution is formed, so the temperature of the jacket wall surface is raised considerably. Must be set. For this reason, the raw fish outlet side, where the heat load is reduced, is overheated and many burns occur. This scorch adheres to the wall surfaces of the casing 102 and the screw feeder 101 and obstructs heat transfer, hardens the raw material fish itself, adversely affects subsequent processes such as pressing and drying, and lowers the yield. Furthermore, at high temperatures, fats and oils are more likely to dissolve, and more so-called extracts such as water and fats will leak out.

By the way, protein denaturation in fish varies depending on the species of fish, but in general, rapid denaturation is observed at around 40°C and is sufficiently achieved at around 60°C, so it is recommended that the current heating temperature exceeds 100°C. Even if it is set quite low, the intended purpose can be sufficiently achieved.
However, in the conventional heat treatment method, it is difficult to set the heating temperature to a low value as described above, and the above-mentioned problems cannot be avoided.

Therefore, an object of the present invention is to provide a method of heat treatment of fish meal that allows efficient protein denaturation even if the heating temperature is set to a relatively low temperature.

Structure of the Invention (Means for Solving the Problems) In order to achieve the above object, the fish meal heating method of the present invention is characterized in that the raw material fish input port and discharge port are located below the substantial heat treatment area. In addition, the raw fish is carried into a heating chamber in which steam at 80 to 95°C is injected to replace at least the air in the heat treatment area with the steam, and the raw fish is placed on an air-permeable conveying means and transferred through the heat treatment area. During this time, the raw material fish is exposed to the steam atmosphere, and the raw material fish is steamed by condensation heat transfer of the steam at 80 to 95°C.

(Example) The present invention will be described in detail below based on an example of an embodiment shown in the drawings.

FIGS. 1a and 1b show a principle diagram of an example of an apparatus for carrying out the method of heat treatment of fish meal of the present invention. This food/meal heating device has a wire mesh belt conveyor or a similar breathable belt conveyor 2 installed in a heating chamber 1 to fill the chamber 1 with steam. Therefore, while the raw material fish W is being transferred, it is evenly exposed to steam and steamed. The heating chamber 1 has a raw material fish input port 3 and a discharge port 4 at both ends.
is provided at a position substantially lower than the region where heat treatment is performed, and is provided so that indoor air, which acts as a heat transfer resistance during steaming, is discharged outdoors due to its specific gravity. Therefore, belt conveyor 2
The conveyors are also laid in a mountain shape as shown in the figure (see Figure 1a), or are installed to provide a head over a short distance by combining an inclined conveyor and a horizontal conveyor. In the case of the belt conveyor 2 shown in FIG. 1b, the entire apparatus can be made short and compact without changing the actual length of the conveyor. The belt conveyor 2 is driven by a drive means (not shown) so as to run at the most suitable speed in relation to the steam temperature. It is also possible to lay a heating pipe 5 over the entire area or part of the bottom of the heating chamber 1 so as to re-evaporate the drain that falls due to gravity and reduce dripping. As the heating tube 5, any known structure and type of heat exchanger can be used, but in this embodiment, a pipe through which steam is passed is used.

The steam filling the heating chamber 1 has a temperature of at least 60°C or more and less than 100°C, preferably about 95 to 80°C.
It is preferred to use a temperature adjusted to 80°C, most preferably about 80°C. Steam that exceeds 95°C will cause the raw fish to be burnt, and steam that exceeds 100°C will cause the quality of the raw fish to be seriously burnt, unevenly steamed, etc.
Steam at temperatures below 60°C may not denature proteins sufficiently depending on the raw material fish, and in particular steam at temperatures below 60°C cannot ensure complete protein denaturation.
The injection direction and position of this steam are carefully considered so as not to directly spray the raw material fish, and in the case of this embodiment, a sparge pipe (not shown) installed under the conveyance surface of the belt conveyor 2 is used. It is done. Note that steam at a temperature of less than 100°C can be easily produced by known pressure manipulation. in this case,
It is preferable to perform gas-liquid separation.

The method of heat treatment of fish meal of the present invention is carried out as follows using an example of the heat treatment apparatus configured as described above.

First, steam adjusted to a predetermined temperature, for example, 95 to 80°C, most preferably 80°C, is injected into the heating chamber 1,
While expelling indoor air, it is replaced with steam. At this time, in order to make the temperature distribution in the heating chamber 1 uniform, it is preferable to supply steam from the lower part of the apparatus (the bottom of the heating chamber), and the air that causes temperature unevenness must be smoothly and reliably discharged. Note that when heating starts, steam is injected from a sparge pipe etc. installed at the bottom of the heating chamber 1 and rises while diffusing.
Air is discharged from the top to the outside of the heating chamber by the rising vapor layer. At this time, if the pressure of the steam ejected from the sparge pipe is high, the flow rate of the ejected steam increases, stirring the indoor air, increasing the amount of residual air, and causing temperature unevenness. Therefore, in order to create a stable steam temperature, the steam injection pressure must be set to an extremely low micropressure (0.01~
0.00Kg/cm ² G). Further, if there is air remaining in the heating chamber 1 after the apparatus is operated, the air, which has a higher specific gravity than the steam, is discharged from the lower inlet 3 or the outlet 4.

When the temperature of the heating chamber 1 reaches the set temperature, raw fish W is continuously introduced from the input port 3 onto the breathable belt conveyor 2 that circulates within the chamber. The raw material fish W carried into the heating chamber 1 overlaps or is scattered in a sparsely dense manner, but is uniformly heated by direct contact with the steam that passes through the belt conveyor 2 or enters every corner of the raw material fish mass from the surroundings. Ru. The raw material fish W is efficiently heated by direct contact condensation heat transfer of steam. In the above-mentioned heating, when the steam condenses through heat exchange with the raw material fish W, its volume shrinks to 1/3000 and the pressure in that part decreases rapidly.
The surrounding steam is constantly drawn to the raw material fish due to this pressure difference, and heat exchange continues. At this time, a water layer film is formed on the surface of the raw material fish W. Since the specific gravity of this aqueous film is greater than that of the surrounding steam, the gravity exceeds the surface tension and the water layer forms droplets and falls without exceeding a certain thickness. For this reason, the thickness of the water film does not exceed a certain level, and as far as the heat transfer resistance of the water film is concerned, steaming is considered to be smaller than conventional boiling. Moreover, the presence of this uniform thin aquarium film prevents the raw material fish W from being partially dried and prevents burns, scorching, uneven steaming, etc. Partial drying of raw material fish W causes physical property changes such as burntness, scorching, and dryness, which changes the heat conduction conditions and moisture penetration conditions of the part, and has the worst effect on quality conditions such as uneven steaming. Become.

Thus, raw fish heated by direct condensation heat transfer of steam under uniform heat distribution finishes protein denaturation at a much lower set temperature than conventionally. According to the conventional heat treatment method for fish meal, scorching and a large amount of broth occur, but with this heat treatment, there is no scorching and the outflow of broth can be kept to an extremely low level as shown in the following table.

Table Heat Treatment Method Heating Temperature Amount of Broiled Soup Outflow (%) Conventional Treatment At Heating Wall Temperature 18 110-116℃ Treatment of the Present Invention Live Steam 95℃ 12 Live Steam 81℃ 8 Effect of the Invention As is clear from the above explanation, the present invention In the method for heat treatment of fish meal of the invention, an input port and a discharge port for raw fish are located below a substantial heat treatment region, and steam at a temperature of 80 to 95° C. is injected to remove at least the air in the heat treatment region. The raw fish is brought into a heating chamber that has been replaced with steam, placed on an air-permeable conveying means, and while being transported through the heat treatment area, the raw fish is exposed to the steam atmosphere, allowing direct contact with the steam to reach every corner. Since the heating is performed by condensation heat transfer, it is possible to achieve even and efficient heating at a uniform temperature. Therefore, according to this heat treatment method, it is possible to denature all of the proteins in raw fish without setting the heating temperature to a high temperature (100°C or higher).For example, if the heating temperature is close to the minimum required heating temperature, Since the temperature can be set as low as possible, about 80°C, it is possible to prevent burns and the like, and to greatly suppress the outflow of extract components. Therefore, even when the raw fish is pressed, dried, and crushed according to known conventional methods to produce fish meal after this heat treatment, the result is a soft meal with no burnt parts and a high moisture content. The process becomes easier and the yield improves.

[Brief explanation of the drawing]

FIGS. 1a and 1b are principle diagrams showing an example of a fish meal heat treatment apparatus for carrying out the method of the present invention;
FIG. 2 shows a conventional fish/meal heat treatment apparatus, in which a is a cross-sectional view and b is a side view of the screw feeder. 1...Heating chamber, 2...Breathable conveyance means, W...
Raw material fish.

Claims (1)

[Claims] 1 Raw material fish is placed in a heating chamber in which the inlet and outlet for the raw material fish are located below the substantial heat treatment area, and in which steam at 80 to 95°C is injected to replace at least the air in the heat treatment area with the steam. is carried in, placed on a breathable conveyance means, and exposed to the steam atmosphere while being transferred to the heat treatment area,
A method for heat treatment of fish and meal, which is characterized by steaming raw fish by condensing heat transfer of steam at 80 to 95°C.