JPS62272934A - Method for treating tuna - Google Patents

Abstract

PURPOSE:To obtain tuna meat which can be thawed or rethawed without causing change in color of lean meat, reduction in quality and dripping, by cutting tuna meat into a specific size, bringing the neat through a water-permeable semipermeable membrane into contact with a water-absorbing material so that the tuna meat is dehydrated. CONSTITUTION:For example, frozen tuna is cut into a given size, the cut tuna meat is optionally thawed completely and brought into contact with a dehydrating sheet which is obtained by sandwiching a water-absorbing material consisting of a high polymer water-absorbing agent (e.g. one obtained by grafting water-soluble monomer such as acrylamide, etc., onto polysaccharide such as starch, etc.) 2 alone or of the high polymer water absorbing agent 2 and a hydrophilic paste agent 5 made of a highly osmotic pressure substance (e.g. CMC) 3 and/or a hydrophilic alcohol (e.g. ethyl alcohol) 4 in between water-permeable semipermeable membranes 1 such as collodion membrane, etc., and sealing the peripheral edge by fusing to dehydrate the tuna meat and to reduce water content.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention is a method for thawing frozen tuna and storing it by keeping it at a low temperature, or refreezing it for use as needed. This invention relates to a tuna processing method that does not deteriorate the color or taste of tuna fish meat when thawed and used according to the requirements.

[Conventional technology]

Tuna is considered a high-quality fish, but 90% of it is caught through deep-sea fishing, flash-frozen, and kept at extremely low temperatures before being sent to Japan. The landed tuna is lol? Chilled tuna that has been frozen, dissected, and kept at a low temperature, or frozen tuna that has been dissected and cut while frozen, is placed on distribution channels. Therefore, all tuna served on the table has gone through the freezing and thawing process, with the exception of tuna from local waters, which is extremely small compared to the total supply of tuna.

[Problem that the invention seeks to solve]

By the way, thawing significantly deteriorates the quality, and when chilled tuna is stored for a long time, it becomes discolored with its unique reddish color. In addition, tuna has a strong lFI+ of autolyzed M
If it is not stored warm at -40°C or below, the distinctive red color will not appear when thawed. Furthermore, even if an attempt is made to extend the shelf life by refreezing a product that has been thawed, the deterioration is even more severe when the product is thawed again, and refreezing is generally considered impossible.

In view of the above circumstances, it is an object of the present invention to provide a method for processing tuna that can retain its unique red color even after frozen and thawed chilled tuna is stored for a considerable period of time and even when it is refrozen and thawed. With the goal.

[Means for solving problems]

The present invention has been made to achieve the above objects,
The gist is a tuna processing method in which tuna meat cut into predetermined sizes is brought into contact with a water-absorbing object via a water-permeable semipermeable membrane to reduce the water content in the tuna meat.

[Specific structure and operation of the invention]

The method of the present invention will be explained in detail below.

The water-permeable semi-permeable membrane (hereinafter referred to as semi-permeable membrane) used in the present invention may be, for example, cellophane, low-stretchability vinylon film, collodion membrane, or a sufficiently fine non-woven membrane [,
A thermoplastic film that is made impermeable and provided with communicating holes for electron beam irradiation, etc., is used.

In addition, as water-absorbing substances, there are cases where a polymer absorbent is used alone, and cases where a polymer absorbent and a hydrophilic glue are used in combination. alcohols alone or in mixtures.

The polymer absorbent mentioned above is one that can gel and retain water when it comes into contact with water, such as polysaccharides such as starch and cellulose, and water-soluble hexamers such as sodium alginate and acrylamide. Graft polymerized products or three-dimensionally crosslinked products of hydrophilic polymers such as polyacrylic acid sorter, polyethylene oxide, carboxymethyl cellulose, and polyvinyl alcohol are used.

In addition, high osmotic substances include, for example, starch syrup produced by acid saccharification or enzymatic saccharification of starch, edible sugars such as pullulan, glucose, fructose, mannitol, sorbyl, and maltitol, mannan, sodium alginate, calaginnan, and gum arabic. Natural water-soluble polymers such as methyl cellulose, carboxymethyl cellulose hilloses, etc., and these pure products or hydrated products can be used alone or in combination.

Hydrophilic alcohols are hydrophilic liquid alcohols that have water absorption properties, such as ethyl alcohol, propylene glycol, glycerin, etc., and these can be used alone or in combination.

In order to dehydrate tuna fish meat using the semipermeable membrane and the water-absorbing object, dehydration seams 1 to 1, which have been recently developed as dehydration tools for food processing, can be suitably used. The dehydration sheet is made by sandwiching the water-absorbing object between two semipermeable membranes, and further sealing the periphery of the semipermeable membrane with G&IV.

The dehydration sheet, which holds the above water-absorbing material in a semi-permeable membrane, has
There are various configurations as shown below.

In other words, (A> As shown in Fig. 1, a dehydration sheet is prepared by sandwiching a polymer absorbent 2 between semipermeable membranes 1 and 1 and sealing the periphery of the semipermeable membranes 1 and 1 by melting or the like. 1~.

(B) As shown in FIG. 2, a polymer absorbent 2 and a hydrophilic glue 5 made of a high osmotic pressure substance 3 and a hydrophilic alcohol 4 are made to coexist, and this is placed between semipermeable membranes 1 and 1. sandwiched between
A dewatering sheet whose periphery is sealed by fusion.

(C) As shown in FIGS. 3(a) and (b), the polymer absorbent 2 is placed on a water-permeable support 6 such as paper, pulp, or cloth (if placed, only one side of the water-permeable support 6 ), or a dehydrating sheet which is sandwiched, a hydrophilic glue 5 is placed on the outside of the support 6, further sandwiched between semipermeable membranes 1, 1, and the periphery is sealed by fusion or the like.

(D) As shown in FIGS. 4(a) and 4(b), the polymer absorbent 2 is placed on the water-permeable support 6 (if placed, the water-permeable support 6 is only on one side) or sandwiched. , this support 6 itself, or a holding body such as another paper, impregnated with a hydrophilic glue 5, is sandwiched between semipermeable membranes 1, 1, and the periphery is sealed by fusion etc. to form a dehydration sheet. .

etc. are known.

In addition, in the dehydration sheet sandwiched between the semipermeable membranes 1, 1, the non-water permeable membrane 7 may be used in place of the semipermeable membrane 2 for one of the semipermeable membranes 1, 1. In addition, when sealing the periphery, it may be bonded with an adhesive, but it is preferable to use a heat-sealable semipermeable membrane 1 and a water-impermeable membrane 7 because the length of 11 m becomes easier. In order to prevent the water-absorbing object from shifting, as shown in FIG. 1, the intermediate portions of the semipermeable membranes 1, 1 may be suitably blue-melted.

To remove moisture from tuna fish meat using the above-mentioned dehydration sheet, sandwich the completely thawed tuna fish meat on the surface of the semipermeable membrane 1 of the dehydration sheet and bring that surface into close contact with the tuna fish meat to keep it at a low humidity. However, only the moisture in the tuna transfers to the dehydration sheet, giving it appropriate elasticity, retaining freshness, and producing excellent tuna fish meat with a unique color and taste of tuna. Even after dehydration, the color and taste are retained.

Moreover, even if it is refrozen and thawed again, there is almost no dripping, and no deterioration in color, taste, etc. is observed.

FIG. 5 shows a tuna processing method incorporating the processing method of the present invention. In other words, the cold principle that was brought ashore was dismantled and 1
It is immersed in water at 0 to 20°C and completely thawed. Thawed tuna is stripped of bones, blood, skin, etc., and polished to a predetermined size.

This polishing is dehydrated to a dehydration rate of 3 to 10% by the method of the present invention at a temperature of 0 to 5°C, and then stored in a refrigerator.

The tuna stored in the refrigerator is taken out as needed and sold as dehydrated tuna. In addition, surplus tuna is refrozen and stored in the freezer, but if necessary, it can be thawed naturally at 0°C and sold as dehydrated tuna. The above dehydrated tuna stored in the refrigerator, refrozen, and rethawed has no difference in color or taste.

Therefore, it becomes easy to adjust the distribution of tuna fish meat in the distribution channel.

In addition, the dehydrated sheet that has absorbed moisture through the above treatment can be exposed to the sun or exposed to hot air.
Absorbed water is released, easily regenerated, and can be used repeatedly. Furthermore, if the semipermeable membrane is not brought into direct contact with the tuna fish meat, but the tuna fish meat is wrapped in cellophane and brought into contact with the semipermeable membrane, contamination of the dehydration sheet can be prevented and repeated use can be facilitated. Become.

Note that the above method can also be used for storing tuna fish meat at home. In addition, the same method is effective for not only tuna but also bonito and other white-tasting fish, but especially at home, etc., after dehydrating fish meat obtained in many cans by fishing etc. by the method of the present invention, By freezing the fish and thawing it naturally before making it edible, fish meat with fresh color and taste can be prepared at any time and consumed without waste.

〔Example〕

Next, the present invention will be explained with reference to Examples.

Example 1 A commercially available frozen tuna was dismantled during freezing to form 800 g or more rolls, which were completely thawed by running tap water at 15° C. for 3 hours. This tuna fish meat was heated for 20 minutes in a refrigerator at 0 to 3°C using the dehydrating sheet shown in Figure 2.
The sample was held for a period of time to remove 5% of the water content. Color measurements were compared using this dehydrated tuna and, as a control, a tuna that had been thawed, drained, kept at 0 to 3°C for 20 hours, and then dehydrated.

We also measured the color of the tuna immediately after it was thawed and drained, which is the starting point common to both.

The color difference meter used was Minolta CR-100, and six points on the surface of each tuna were measured. ), and the dehydration effect on flesh color was investigated.

Although it is well known, the L value expresses lightness and darkness, and the larger the number, the brighter it is, and the a value and b value represent redness and darkness, respectively.
It has a yellowish tinge, and the larger the number, the greater the reddish or yellowish tinge.

In addition, ◎ indicates a common part, O-dehydrated sample, and . indicates a control.

As is clear from the figure, dehydration deepens the color (decreases brightness), increases redness and yellowness, and improves the color of the tuna.

Example 2 Using the dehydrated tuna of Example 1 and the control tuna, each was placed in a polyethylene bag and kept in a -40°C freezer for 48 hours to completely freeze. Re-unzip this and
The change in a value at that time was measured. The results are shown in FIG.

As can be clearly seen from the figure, the dehydration process produces a stronger reddish tinge during refreezing and rethawing.

Example 3 The change in flesh color was determined by comparing the dehydrated and refrozen tuna of Example 2 with the conventionally frozen tuna. The method is to naturally thaw tuna that has been dehydrated and refrozen and commercially available frozen tuna in a refrigerator at 0 to 3°C, and calculate the 1-value, a-value, and a value during and 24 hours after thawing. b Koma was measured. The binding is shown in FIGS. 8(a), (b), and (C).

The amount of dehydration is reddish (aWj) for the bundling, freezing ■, and 1.

It is strong against yellowish taste (bl+n) and b, but it is the first time to defrost it! II is superior to the conventional control product. However, as the thawing progresses, the contrast! The amount of dehydration in the case of 1 eup was significantly higher after 24 hours of pre-thawing.

〔effect〕

As mentioned above, the tuna fish meat processed according to the present invention has a strong red color compared to the tuna fish meat 1), and the tuna fish meat processed according to the present invention has a strong red color, and the tuna fish meat processed according to the present invention has a strong red color, and the tuna fish meat processed by the process of the present invention has a strong red color and can be obtained by 4t
Because of this, there is no tripping during thawing, and refreezing is possible without degrading the quality, greatly increasing the value of tuna to retailers.

[Brief explanation of drawings]

1 to 4 (a) and (b) are longitudinal cross-sectional views of dehydration sheets of various configurations that can be suitably used in the present invention,
Figure 5 is a diagram showing the process of lυ tuna processing incorporating dehydration treatment, and Figure 4 (a), (b), and (C) show the effect of dehydration treatment on flesh color in comparison with the control. Figure 7 shows the effect of dehydration on redness compared to the control, and Figure 8 (a), (b), and (c) show the effect of dehydration on fish meat after dehydration and re-treatment. FIG. 2 is a diagram showing a comparison between frozen and re-thawed tuna and commercially available frozen tuna that was naturally thawed in a refrigerator as a control. 1... Water permeable semi-permeable membrane (semi-permeable membrane), 2...
・Polymer absorbent, 3...High osmotic pressure substance, 4...
... Hydrophilic alcohol, 5 ... Hydrophilic glue, 6 ... Water permeable support, 7 ... Water impermeable membrane.

Claims (1)

[Claims] A method for processing tuna, which comprises bringing tuna meat cut into a predetermined size into contact with a water-absorbing object through a water-permeable semi-permeable membrane to reduce the water content in the tuna meat.