JP7580141B2 - Fish meal production method - Google Patents

Description

The present invention relates to a method for producing fish meal using sharks as a raw material.

Fish meal, that is, powder made from fish, is used as a direct or indirect ingredient in various foods, either dried or pulverized. Fish meal is also useful as feed in the livestock and fishing industries.

In recent years, in response to rising fish meal prices, there is a demand for methods to produce fish meal efficiently and at low cost.

For example, Patent Document 1 discloses a method for producing fish meal, which uses a process of stirring, cutting and drying raw fish material under vacuum or reduced pressure conditions to produce fish meal from horse mackerel, sardines and other fish.

JP 2012-170411 A

The inventors focused on this technology of drying fish raw materials under reduced pressure and attempted to produce fish meal using sharks as a raw material. However, due to the high collagen content of sharks, the collagen components stuck to the inside of the production equipment, and as a result, they were faced with the problem that drying of the fish raw materials under reduced pressure conditions could not be achieved and fish meal could not be produced satisfactorily.

With the exception of some parts, sharks are not widely used in the market due to factors such as the ammonia odor that develops over time, but they are still a useful source of animal protein.

After extensive research, the inventors have come to the novel discovery that good fish meal can be produced by first carrying out a specific enzymatic treatment to change the protein structure so that the protein in the collagen portion is more easily broken down, then carrying out an enzymatic treatment to break down the protein, and then drying the material that has undergone these treatments under reduced pressure conditions.

The present invention was made based on the above new findings, and aims to provide a method for efficiently producing fish meal using sharks as a raw material.

In order to achieve the above object, the present invention provides:
a grinding step for grinding the shark meat;
a preliminary enzyme treatment step in which the material that has been subjected to the crushing step is heated and stirred while adding thiol protease so as to facilitate decomposition of collagen , and the enzymatic reaction is carried out at 60° C. or less for 1 to 3 hours at a pH of 7 to 9 ;
an enzyme treatment step of adding protease to the material that has been subjected to the preliminary enzyme treatment step, stirring the mixture, and carrying out an enzyme reaction at 60° C. or less for 1 to 3 hours at a gauge pressure of −85 kPa or less ;
an enzyme deactivation step of further heating the member that has been subjected to the enzyme treatment step;
This is a fish meal production method characterized by including a drying process in which the material that has undergone the enzyme deactivation process is dried under reduced pressure.

When producing fish meal from sharks, enzyme reactions can be carried out under reduced pressure, which allows proteins to be broken down at relatively low temperatures, leading to the efficient and low-cost production of high-quality fish meal. By giving collagen a protein structure that is easily broken down prior to the enzyme reaction, the efficiency of fish meal production can be further improved.

The addition of thiol protease improves the efficiency of collagen decomposition in the enzyme treatment process.

In addition, in the preliminary enzyme treatment step, it is preferable to add a buffer in addition to the first enzyme.

This results in a neutral to alkaline state during the preliminary enzyme treatment process, accelerating structural changes in proteins caused by the first enzyme.

FIG. 1 is a diagram showing the process for producing fish meal according to the present invention.

In the present invention, sharks refer to fishes belonging to either the superorder Lamniformes or the superorder Squamata of the order Scallops, and specific examples include the blue shark, the cat shark, the great white shark, and the hammerhead shark. Shark meat refers to raw or frozen parts of sharks other than the fins.

The grinding process (Fig. 1/S11) is a process for grinding shark meat. Any known grinding method may be used as necessary, and there is no particular restriction on the size of the ground material, but it is sufficient to grind the material to a size that is easy to mix and stir, taking into account the next process.

In the preliminary enzyme treatment step (S13 in Fig. 1), the material that has been through the crushing step (S11 in Fig. 1) is heated and stirred while adding a first enzyme that changes the protein structure so that collagen can be easily decomposed, to cause an enzymatic reaction. When heating and stirring, water may be added as necessary.

As the first enzyme, various enzymes that change the protein structure so that collagen can be easily decomposed may be used, but thiol proteases are preferred, and papain, ficin, bromelain, and the like are particularly preferred. Collagenase can also be used as the first enzyme. The amount of the first enzyme added is preferably 0.2 to 15 wt % of the weight of the material that has been subjected to the crushing step (Fig. 1/S11).

In the preliminary enzyme treatment step (S13 in FIG. 1), a buffering agent may be added as a pH adjuster to the material that has been through the grinding step (S11 in FIG. 1). Known materials may be used as the buffering agent, and may be selected from, for example, acetic acid, citric acid, tartaric acid, fumaric acid, sodium lactate, sodium bicarbonate, etc.

The preliminary enzyme treatment step (Fig. 1/S13) is preferably carried out at 60°C or less for 1 to 3 hours at a pH of about 7 to 9.

If necessary, the material that has undergone the preliminary enzyme treatment step (Fig. 1/S13) may be further heated to inactivate the first enzyme (preliminary enzyme inactivation step (Fig. 1/S15)).

If a preliminary enzyme inactivation step (Fig. 1/S15) is performed, it is preferable to carry out the step at 70-90°C for about 0.5-3 minutes, after which the mixture is cooled naturally or by other methods.

The preliminary enzyme treatment step (Fig. 1/S13) and the preliminary enzyme inactivation step (Fig. 1/S15) may be carried out in a processing device capable of reducing pressure, such as a vacuum dryer. However, if it is preferable to separate the liquid components of the material after the preliminary enzyme inactivation step (Fig. 1/S15) in the subsequent steps, the material may be treated in a device other than a processing device capable of reducing pressure, and then the material may be subjected to solid-liquid separation by a method such as centrifugation to adjust the solid concentration (solid-liquid separation step (Fig. 1/S16)).

The material that has undergone the preliminary enzyme treatment step (Fig. 1/S13) (and the preliminary enzyme deactivation step (Fig. 1/S15)) is added with water as necessary and placed in a processing device that can reduce pressure, where a second enzyme that breaks down proteins is added and stirred to cause an enzymatic reaction under reduced pressure (enzyme treatment step (Fig. 1/S17)).

The second enzyme may be any enzyme capable of decomposing fish proteins (i.e., proteins after collagen has been rendered easily decomposable in the preliminary enzyme treatment process), but proteases, particularly acidic proteases and neutral proteases, are preferred. Enzymes such as Sumiteam AP, Sumiteam FP (Shin Nippon Chemical Industry Co., Ltd.), Proteax, Acidic Protease UF "Amano" SD, and Protease M "Amano" SD (Amano Enzyme Co., Ltd.) may also be used. ("Sumiteam" and "Proteax" are registered trademarks.) By appropriately selecting the enzyme used as the second enzyme, various characteristics can be imparted to the nutritional content, odor, taste, etc. of the fish meal product. The amount of the second enzyme added is preferably 0.05 to 5 wt % of the weight of the material that has been subjected to the preliminary enzyme treatment process (Fig. 1/S13) and water added as necessary.

The enzyme treatment step (Fig. 1/S17) is preferably carried out at 60°C or less for 1 to 3 hours with the pressure inside the apparatus at a gauge pressure of -85 kPa or less. There is no need to adjust the pH, and it is carried out at a value of around 2 to 9.

The material that has undergone the enzyme treatment step (Fig. 1/S17) is further heated to inactivate the second enzyme (enzyme inactivation step (Fig. 1/S19)).

The enzyme inactivation step (Fig. 1/S19) is preferably carried out at 60-80°C for about 3-15 minutes, after which the mixture is cooled naturally or by other methods.

The materials that have undergone the enzyme deactivation step (S19 in Fig. 1) are dried while being stirred under reduced pressure (drying step (S21 in Fig. 1)). The drying time depends on the weight of the materials that have been put in, etc. It is preferable to perform drying at a drying temperature of 35 to 70°C and with a gauge pressure inside the device of -85 kPa or less, and it is more preferable for the drying temperature to be 35 to 40°C.

Below, one embodiment of the method for producing fish meal using sharks as a raw material according to the present invention will be described with reference to the drawings, but the scope of the present invention is not limited to these examples.

(Example)
100 kg of thawed blue shark fillet was roughly cut and placed in a super mixer, where it was pulverized by processing at 100 rpm for 1 minute and then at 500 rpm for 1 minute (FIG. 1/S11).

The crushed blue shark fillet was transferred to an open heating vessel, and the same amount of water was added, followed by thiol protease (2 kg) and sodium bicarbonate as a buffer (pH adjuster), and the mixture was adjusted to approximately 50°C and heated and stirred for 2 hours (Fig. 1/S13). The pH at that time was approximately 8.

The heating vessel was then kept at 80°C for 1 minute to inactivate the thiol protease (Fig. 1/S15), and the resulting fluid component was placed in a vacuum dryer.

200 g of acid protease was then added as the second enzyme, and the mixture was heated and stirred at approximately 55°C for 3 hours (Fig. 1/S17). The pressure inside the vacuum dryer at that time was -88 to -98 kPa in gauge pressure.

After 3 hours of heating and stirring, the temperature inside the vacuum dryer was adjusted to 70°C and the material was heated for 10 minutes (Fig. 1/S19), after which it was cooled. During this time, the vacuum inside the vacuum dryer was maintained at the same reduced pressure and the material continued to be stirred, and after 5 hours, 14.3 kg of shark fish meal was obtained (Fig. 1/S21).

(Comparative Example)
In the examples, shark meat was processed in the same manner except for omitting the preliminary enzyme treatment step (Figure 1/S13) and the preliminary enzyme inactivation step (Figure 1/S15). However, collagen components adhered to the inner walls of the vacuum dryer during the drying step (Figure 1/S21), and fish meal could not be obtained.

Thus, according to the present invention, the protein structure of the collagen portion is changed by carrying out a specific enzyme treatment prior to drying the raw shark material under reduced pressure conditions, making it easier to decompose the collagen in the subsequent enzyme treatment that breaks down the protein. This makes it possible to produce good fish meal by drying the material that has undergone these treatments under reduced pressure conditions.

In the above example, the material that had undergone the enzyme deactivation process (Fig. 1/S19) was dried while being stirred under reduced pressure (drying process (Fig. 1/S21)). However, depending on the required form and properties of the fish meal, a further drying process may be carried out using a method such as hot air drying.

In addition, in the above examples, a preliminary enzyme inactivation step (Fig. 1/S15) is performed, but this step may be performed as necessary. That is, for example, if it is known in advance that the first enzyme does not interfere with the enzymatic reaction of the second enzyme in the enzyme treatment step, the preliminary enzyme inactivation step (Fig. 1/S15) may be omitted. In this case, the first enzyme is inactivated together with the second enzyme in the enzyme inactivation step (Fig. 1/S19).

In addition, in the above examples, fillet meat was used as shark meat, but so-called "fish tails" including organs, tails, heads, skin, and bones may also be used as shark meat.

The resulting fish meal may then be further processed, such as crushed and classified, depending on the intended use.

Claims (2)

a grinding step for grinding the shark meat;
a preliminary enzyme treatment step in which the material that has been subjected to the crushing step is heated and stirred while adding thiol protease so as to facilitate decomposition of collagen , and the enzymatic reaction is carried out at 60° C. or less for 1 to 3 hours at a pH of 7 to 9 ;
an enzyme treatment step of adding protease to the material that has been subjected to the preliminary enzyme treatment step, stirring the mixture, and carrying out an enzyme reaction at 60° C. or less for 1 to 3 hours at a gauge pressure of −85 kPa or less ;
an enzyme deactivation step of further heating the member that has been subjected to the enzyme treatment step;
A method for producing fish meal, comprising a drying step of drying the material that has undergone the enzyme deactivation step under reduced pressure. The method for producing fish meal according to claim 1 , characterized in that in the preliminary enzyme treatment step, a buffer is added in addition to the first enzyme.

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