JP6995951B1 - Cultured tuna and tuna farming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cultured tuna containing a monounsaturated fatty acid (MUFA), particularly a long-chain monounsaturated fatty acid (LongChainMonoUnsaturatedFattyAcid: LCMUFA) in a high fatty acid composition ratio. SOLUTION: The content of monounsaturated fatty acid and its derivative in the lipid of the edible portion is 32% or more in the fatty acid composition ratio, and the cultured tuna. Preferably, the cultured tuna has a total content of monovalent unsaturated fatty acids having 20 or more carbon atoms and derivatives thereof in the lipid of the edible portion of 3.8% or more in terms of fatty acid composition ratio. Furthermore, a method of cultivating tuna by cultivating tuna under breeding management conditions. [Selection diagram] Fig. 1

Description

The present invention relates to cultured tuna containing a high content of monounsaturated fatty acids, and a method for culturing tuna to obtain the cultured tuna.

Monounsaturated Fatty Acid (MUFA) is a fatty acid mainly contained in plants and fish. It is known that when a human ingests this as a food or the like, it has a health-promoting effect such as lowering LDL-cholesterol in blood. Among the MUFAs, those with 20 or more carbon atoms called long chain monounsaturated fatty acid (LCMUFA) are atherosclerosis (Non-Patent Document 1) and diabetes (Patent Document 1). , Metabolic syndrome (Patent Document 2), etc. have been reported to be effective in prevention and treatment. Patent Document 3 discloses a method for producing a free monounsaturated fatty acid (LCMUFA) having 20 and / or 22 carbon atoms or a lower alcohol ester thereof from a marine product raw material. This method is mainly aimed at producing materials such as pharmaceuticals and health foods containing a high concentration of LCMUFA.

It has been reported that the fatty acid composition ratio of LCMUFA in the fat content of tuna differs between natural fish and farmed fish, and is high in natural fish (Non-Patent Document 2). Further, it has been reported that in the fat content of tuna, the fatty acid composition ratio is high in the toro portion of both MUFA and LCMUFA (Non-Patent Document 3).

Japanese Unexamined Patent Publication No. 2001-294525 International release 2012/121080 International release 2016/002868

Yang, et al., Mol. Nutr. Food Res., 60 (10): 2208-2218 (2016) Nakamura, et al., Food Chem., 103: 234-241 (2007) Journal of Japan Society for Bioscience and Biotechnology, Vol. 58, No. 1, pp. 35-42 (1984)

As described above, various studies have been made on purifying LCMUFA and using it as a pharmaceutical product, but no study has been made on producing cultured fish as a food containing a high concentration of LCMUFA. It is known that cultured tuna has a lower fatty acid composition ratio of MUFA and LCMUFA than natural tuna, but in order to stably provide tuna containing MUFA and LCMUFA at high concentrations, in cultured tuna, It is desired that MUFA and LCMUFA containing MUFA and LCMUFA in a fatty acid composition ratio equal to or higher than that of natural tuna are stably present at a certain ratio or higher.

An object of the present invention is to provide cultured tuna containing MUFA in a high fatty acid composition ratio. Furthermore, it is an object of the present invention to provide cultured tuna containing LCMUFA in a high fatty acid composition ratio. Another object of the present invention is to provide a method for culturing tuna for obtaining cultured tuna containing MUFA in a high fatty acid composition ratio. Furthermore, it is an object of the present invention to provide a tuna farming method for stably obtaining cultured tuna containing LCMUFA at a high fatty acid composition ratio.

The present invention provides the following.
(1) Cultured tuna in which the content of monounsaturated fatty acids and their derivatives in the lipids of the edible portion is 32% or more in terms of fatty acid composition ratio.
(2) The cultured tuna according to (1), wherein the total content of monovalent unsaturated fatty acids having 20 or more carbon atoms and their derivatives in the fat of the edible portion is 3.8% or more in terms of fatty acid composition ratio.
(3) The cultured tuna of (1) or (2), which is a bluefin tuna.
(4) A tuna farming method for growing any of the cultured tuna (1) to (3) by culturing the tuna under breeding management conditions.

According to the present invention, it is possible to provide cultured tuna containing MUFA in a high fatty acid composition ratio. Furthermore, it becomes possible to provide cultured tuna containing LCMUFA in a high fatty acid composition ratio. Further, it becomes possible to provide a tuna farming method for obtaining a farmed tuna containing MUFA in a high fatty acid composition ratio. Furthermore, it becomes possible to provide a tuna farming method for stably obtaining cultured tuna containing LCMUFA at a high fatty acid composition ratio.

A partial anatomical view and a cross-sectional view of the tuna are shown. FIG. 1 (A) shows a partial anatomical view of tuna seen from the body side. FIG. 1B is a cross-sectional view taken along the line AA'of the tuna of FIG. 1A which has not been dissected. It is a photograph showing the site used for fatty acid analysis of tuna. FIG. 2A is a photograph of the abdominal kami portion of the edible portion of tuna. FIG. 2B is a photograph of the back kami portion of the edible portion of tuna.

<Cultured tuna>
The cultured tuna of the present invention is characterized in that the content of monounsaturated fatty acids and derivatives thereof in the fat of the edible portion is 32 % or more in terms of fatty acid composition ratio. By having the above-mentioned characteristics, the cultured tuna of the present invention can be expected to have a health-promoting effect and a disease-preventing effect when ingested by humans. It can also be expected to be useful as a raw material for pharmaceuticals, health foods, etc.

As used herein, the term "tuna" refers to teleost fish belonging to the genus Tuna of the Perciformes Scombridae. Examples of such hard-bone fish include black tuna (Thunnus orientalis), yellowfin tuna (Thunnus maccoyii), bigeye tuna (Thunnus obesus), albacore tuna (Thunnus allalunga), yellowfin tuna (Tunaguna), and yellowfin tuna (Tunnus). Thunnus thynnus) and the like.

As used herein, the term "cultured tuna" refers to tuna that has been fed and bred under breeding management conditions such as cages before shipment, regardless of the length of the period. "Cultured tuna" includes both fully-cultured tuna and farmed tuna. On the other hand, "natural tuna" refers to tuna that have not been fed or bred under breeding management conditions until shipment after being caught at sea. The term "breeding management conditions" as used herein means that the environment is such that various conditions are artificially controlled. Specific conditions will be described in the section "Tuna farming method".

As used herein, the term "edible portion" usually refers to all parts that humans eat, and mainly includes muscle tissue, and other parts such as around the eyeball and internal organs. FIG. 1 shows a partial anatomical view and a cross-sectional view of tuna. FIG. 1 (A) shows a partial anatomical view of tuna seen from the body side. The tuna 1 is a state in which the muscular tissue is cut off along the spine from the center of the back to the center of the abdomen, leaving the head 2. The dissected muscular tissue is divided into 6 parts: back kami 3, back naka 4, back simo 5, abdominal kami 6, abdominal naka 7, and abdominal simo 8 from the cranial side to the caudal side. Divided. The back kami 3, the back Naka 4, and the back shimo 5 are the parts generally called lean meat, the abdominal kami 6 is the part called the large toro and the middle toro, and the abdominal Naka 7 and the abdominal shimo 8 are the parts called the middle toro. FIG. 1B is a cross-sectional view taken along the line AA'of the tuna of FIG. 1A in an undissected state. There is a large fatty tuna 10 around the abdominal cavity 9 of the tuna 1, a medium fatty tuna 11 on the body side, and a lean meat 12 on the dorsal side. In the muscle tissue, there are 13 bloods, 14 bloods, 16 tempers around the spine 15, and 18 parts called splits 18 at the base of the dorsal fin 17, which are generally classified as lean and edible. It is a part included in the part.

As used herein, the term "monovalent unsaturated fatty acid" refers to a fatty acid having one unsaturated bond in a carbon chain, also referred to as monoenoic acid or MUFA, and is a polyunsaturated fatty acid (polyenoic acid, PolyUnsaturated Fatty Acid: It is distinguished from PUFA) and saturated fatty acid (SFA). In the present specification, MUFA refers to decenoic acid (C10: 1), myristolenic acid (C14: 1), pentadecenoic acid (C15: 1), palmitoleic acid (C16: 1), heptadecenoic acid (C17: 1), and the like. Oleic acid (C18: 1), buxenoic acid (C18: 1), eicosenoic acid (C20: 1), docosenoic acid (C22: 1), tetracosenoic acid (nervonic acid) (C24: 1) and the like are included. In particular, typical MUFAs contained in fish include myristoleic acid, palmitoleic acid, oleic acid, eicosenoic acid, docosenoic acid and tetracosenoic acid.

Among the above MUFAs, the cultured tuna of the present invention preferably contains long-chain monounsaturated fatty acids such as eicosenoic acid (C20: 1), docosenoic acid (C22: 1), and tetracosenoic acid (C24: 1). .. As used herein, the term "long-chain monounsaturated fatty acid" is also referred to as LCMUFA and refers to a MUFA containing a carbon chain having 20 or more carbon atoms. Examples of the eicosenoic acid include n-11, n-9 (gadoleic acid), n-7 (gondoleic acid) and the like. Examples of docosenoic acid include n-11 (setrain acid) and n-9 (erucic acid). Examples of the tetracosenoic acid include n-9 (nervonic acid) and the like. Here, "n" means that a double bond exists in the nth carbon-carbon bond counting from the methyl end of the carbon chain.

As used herein, the term "derivative" of MUFA refers to an ester, a metal salt, or the like while retaining the skeleton of a fatty acid. Examples of esters include glyceryl esters such as triglycerides, diglycerides and monoglycerides, as well as methyl esters, ethyl esters and isopropyl esters.

The cultured tuna of the present invention contains MUFA and its derivatives in a fatty acid composition ratio of 32 % or more, preferably 35 % or more, more preferably 38 % or more, and most preferably 39 % or more. Further, preferably, the cultured tuna of the present invention contains LCMUFA and its derivatives in a fatty acid composition ratio of 3.8% or more, more preferably 7.0% or more, still more preferably 10.0% or more, and most preferably 10.0% or more. Contains 15.0% or more.

As used herein, the term "fatty acid composition ratio" refers to the amount of various fatty acids contained in the fat contained in the sample and the lipolytic product as a weight ratio (%) per 100 g of total fatty acid. The measuring method is not particularly limited, but it is preferable to measure according to the "Standard Oil and Fat Analysis Test Method" edited by the Japan Oil Chemists' Society. That is, it is a method of using a boron trifluoride-methanol method (BF ₃ -MeOH method) to saponify a lipid to remove an unkenzide, obtain a free fatty acid, esterify it, and measure it by gas chromatography.

<Tuna farming method>
The method for culturing tuna of the present invention is characterized in that the above-mentioned cultured tuna is cultivated by culturing the tuna under breeding management conditions.

1. 1. Tuna to be cultivated The tuna cultivated by the culturing method of the present invention may be artificially hatched tuna or natural seedling tuna.

2. 2. Aquaculture under breeding management conditions The tuna to be cultivated above are transferred to a dedicated cage or aquarium and cultivated under breeding management conditions. As conditions for aquaculture, it is necessary to adjust and manage feeding, water temperature, fish density, etc.

(1) Feeding It is preferable to feed the tuna by spraying it in the cage at least once a day. It is preferable to feed the bait with a large amount of MUFA, particularly LCMUFA. As the bait containing a large amount of MUFA, for example, mackerel and sardines containing a large amount of oleic acid can be used. Fish as foods rich in LCMUFA include Alaska pollack, mackerel, cod, walleye pollock, rockfish, coho salmon, coho salmon, capelin, taihei trout, nigiri, capelin, shishamo, herring, and rockfish. ), Coho salmon, mutsu, rockfish, capelin, and sablefish are known, and these fish can be fed as raw, minced or moist pellets. The proportion of these fish in the total amount of feed is 50% by weight or more, 60% by weight or more, 70% by weight or more, preferably 80% by weight or more, more preferably 85% by weight or more, still more preferably. It can be 90% by weight or more, more preferably 95% by weight or more, and particularly preferably 100% by weight. Alternatively, for example, the compound feed contains a large amount of LCMUFA such as sardine oil, saury oil, salmon oil, muscle oil, shark liver oil, whale oil, tara liver oil, rapeseed oil, mustard oil, cabbage seed oil, jojoba oil, and meadowfoam oil. You may feed a mixture of oils and fats. In addition, the compound feed usually contains fish meal, wheat flour, soybean oil residue, refined fish oil and the like.

The fatty acid composition ratio of MUFA in the fat content of the feed is preferably 20% or more, particularly preferably 30% or more. The fatty acid composition ratio of LCMUFA is preferably 5.0% or more, particularly 10.0% or more, and more preferably 15.0% or more.

(2) Water temperature The water temperature in the cage or aquarium for culturing tuna is preferably 15 to 28 ° C, particularly preferably 20 to 26 ° C. Since tuna cages are usually installed on the sea, it is difficult to artificially adjust the water temperature inside the cage after installation. For example, by appropriately selecting the location of the cage, the desired temperature can be obtained. It is possible to carry out aquaculture under conditions.

(3) Fish density The density of the tuna in the fish cage and the water tank is preferably 0.7 to 4.0 kg / m ³ , especially 1.5 to 3.0 kg / m ³ . The size of the cage and the aquarium is not particularly limited as long as each individual tuna can swim without contacting other individuals, but for example, the size is about 50 to 80 m in length and width and 12 to 25 m in depth. Can be.

(4) Period The aquaculture under the above aquaculture conditions is carried out for 7 days or more, more preferably 30 days or more, more preferably 60 days or more, more preferably 90 days or more before shipment, and after the aquaculture period under the above aquaculture conditions. Cultured tuna is preferably shipped immediately.

The method of the present invention makes it possible to obtain cultured tuna containing MUFA, particularly LCMUFA, at a high fatty acid composition ratio by culturing the tuna under the above-mentioned breeding management conditions.

Hereinafter, the present invention will be described in more detail in Examples, but the following Examples are not limited to the present invention.

<Example 1. Feeding test for tuna in multiple farms>
Feeding tests for bluefin tuna were conducted at four farms and farms A to D, respectively. Table 1 shows the breeding management conditions at each farm. The breakdown of the food in the table shows the ratio of each material calculated from the amount of food fed throughout the feeding test period.

<Example 2. Fatty acid composition analysis of bait ＞
The fatty acid composition ratio of the fat contained in the saury, mackerel, and sardine used as food was determined. Each fish was homogenized one by one and used for analysis. After adding 50 μL of 10 mg / mL methyl tricosaneate as an internal standard to 100 to 200 mg of the homogenized sample, 1 mL of distilled water was added, and then 5 mL of a chloroform: methanol = 1: 1 solution was added and stirred. After centrifugation (3000 rpm, 10 minutes, 10 ° C.), the lower layer was filtered through a cotton plug and dried under reduced pressure to extract the lipid. 300 μL of 0.5 M sodium hydroxide / methanol solution was added to the obtained lipid, and the mixture was stirred and heated at 100 ° C. for 9 minutes under a nitrogen atmosphere to saponify. After cooling, 400 μL of boron trifluoride methanol solution (manufactured by ALDRICH) was added, stirred, and heated at 100 ° C. for 7 minutes under a nitrogen atmosphere for methyl esterification. After cooling, 600 μL of distilled water and 600 μL of hexane were added and stirred, and then centrifugation was performed. The upper layer was recovered, dehydrated with anhydrous sodium sulfate, and dried under reduced pressure to obtain a fatty acid methyl ester. Gas chromatographic analysis was performed on the hexane solution of fatty acid methyl ester under the following conditions.
Column (filler, size): DB-WAX (length 30 m x inner diameter 250 mm, film thickness 0.25 μm, manufactured by Agilent Technologies)
Column temperature: Hold at 170 ° C for 5 minutes, raise to 240 ° C at 1.5 ° C / min, and hold for 10 minutes. Injection port temperature: 250 ° C.
Carrier gas: helium Flow rate: 1.07 mL / min Fatty acid was identified by determining the retention time of each component of the fatty acid standard in advance. In addition, the amount of each fatty acid was calculated from each peak of the sample based on the peak area of the standard product having a known concentration. Table 2 shows the composition ratios of various fatty acids of saury, mackerel, and sardine. In Table 2, the composition ratios are all shown by mean ± standard deviation (SD).

<Example 3. Fatty acid composition analysis of farmed tuna in each farm>
Tuna cultivated at each farm for a specified period of time were immediately landed and put on the machine. For each tuna in each farm, 200 g of abdominal kami (toro part) was cut out and used as a sample. Only the tuna from farm A and 200 g of back kami (lean part) were also cut out. FIG. 2 shows the specific collection sites of the Toro portion and the lean portion of the sample. (A) is a photograph of the real thing corresponding to the part of the abdominal kami 6 of the tuna in FIG. The abdominal kami 6 is further divided into a large toro 10 and a medium toro 11 on the ventral side, and the portion of the large toro 10 was used for the measurement as shown in the figure as the analysis site of the "toro". (B) is a photograph of the real thing corresponding to the part of the back kami 3 of the tuna in FIG. For the measurement, of the red meat 12 portion of the back kami 3, the portion closer to the dorsal fin was used as the analysis site of the “red meat” as shown by the frame line in the figure. The obtained samples were cut into pieces of 15 g each and analyzed for fatty acid composition by the same method as in Example 2. Table 3 shows the measurement results of the samples from each farm. In Table 3, the composition ratios are shown by mean ± standard deviation (SD) and maximum / minimum.

The fatty acid composition ratios of MUFA of the conventional natural tuna and cultured tuna disclosed in Non-Patent Document 2 are 26.6 and 28.5 to 31.9%. The fatty acid composition ratios of LCMUFA of natural tuna and cultured tuna are 6.7 and 1.6 to 2.8%. It was shown that the contents of both MUFA and LCMUFA of the cultured tuna cultivated in the farms A to D were higher than those of these known tuna, particularly the cultured tuna.
The cultured tuna of the present invention and the method for culturing tuna include the following embodiments.
[1] Cultured tuna in which the content of monounsaturated fatty acids and their derivatives in the lipids of the edible portion is 32% or more in terms of fatty acid composition ratio.
[2] A cultured tuna in which the total content of monovalent unsaturated fatty acids having 20 or more carbon atoms and their derivatives in the fat of the edible portion is 3.8% or more in terms of fatty acid composition ratio.
[3] The cultured tuna of [1] or [2], which is a bluefin tuna.
[4] A tuna farming method for growing the cultured tuna according to any one of [1] to [3] by culturing the tuna under breeding management conditions.

The cultured tuna and the method for culturing tuna of the present invention can be used in the food industry field and the like.

Claims (3)

The content of monounsaturated fatty acids and their derivatives in the fat of the edible portion is 32% or more in terms of fatty acid composition ratio , and the monovalent unsaturated fatty acids having 20 or more carbon atoms in the lipids of the edible portion and their derivatives thereof. A cultured tuna having a total content of derivatives of 3.8% or more in terms of fatty acid composition . The cultured tuna according to claim 1 , which is a bluefin tuna. The method for culturing tuna, which comprises culturing the cultured tuna according to claim 1 or 2 by culturing the tuna under breeding management conditions.

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