Ergothioneine-containing feed and farmed fish fed with said feed

Abstract

To provide plant-based ergothioneine-containing feed that can stably raise farmed fish in order to solve the problem that when using plant raw materials in providing ERG-containing feed, the amount of added plant material will increase to obtain ERG rich-feed so as to cause an eating disorder.SOLUTION: By developing ergothioneine-rich feed made from solid fermented Aspergillus oryzae, it has become possible to raise farmed fish stably without causing an eating disorder in the farmed fish. By raising farmed fish using such feed, it is possible to provide farmed fish with excellent color and taste.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technical field of feed containing ergothioneine (hereinafter, sometimes referred to as ERG) and the raising of farmed fish using such ERG-containing feed. [Background technology]

[0002] Fishmeal, which is high in protein and contains a balanced amount of amino acids required by fish, and fish oil, which contains essential fatty acids, have been used as feed for farmed fish. However, the fish catches from which fishmeal and fish oil are derived have been declining worldwide, causing prices to soar. This has led to a demand for the development of sustainable alternative fishmeal feeds. The use of such alternative fishmeal feeds is expected to add greater value to farmed fish. However, it is known that alternative fishmeal feeds made from plant or animal ingredients can cause feeding disorders in farmed fish, especially marine fish.

[0003] It has been reported that mushroom-derived ergothioneine inhibits the activity of polyphenol oxidase (PPO), which is involved in the blackening of crustaceans and the discoloration of fish blood vessels (Non-Patent Document 1: Food and Containers (2011) Vol. 52, No. 7). Ergothioneine not only has potent antioxidant properties, but also has physiological effects such as elastase inhibition and tyrosinase inhibition, and is reported to be involved in the body's oxidation defense system. Applications of ergothioneine in the beauty and food fields, such as skin whitening and wrinkle prevention, as well as in the medical field, are being attempted. Therefore, there is hope for the development of farmed fish feed containing ergothioneine, not only for the purpose of preventing fish discoloration but also for the purpose of developing farmed fish as functional foods containing ergothioneine.

[0004] Methods for producing ergothioneine have been attempted, including extraction from basidiomycetes such as Pleurotus cornucopius, chemical synthesis, and fermentation using microorganisms. Extraction from basidiomycetes such as Pleurotus cornucopius takes time to obtain raw materials and is not suitable for mass production. To obtain large amounts of ergothioneine, research has been conducted on fermentation using bacteria or yeast capable of assimilating C1 compounds (Patent Document 1: WO 2016 / 104437), as well as fermentation using microorganisms in which ergothioneine biosynthesis genes have been overexpressed (Patent Document 2: WO 2017 / 150304).

[0005] However, ergothioneine obtained by this method is very expensive, and its incorporation into farmed fish feed is not cost-effective. Furthermore, when genetically modified microorganisms are used, evaluation and management under the Feed Safety Act is required, which is an obstacle to feed development. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2016 / 104437 [Patent Document 2] International Publication No. 2017 / 150304 [Non-patent literature]

[0007] [Non-Patent Document 1] Food and Containers (2011) vol. 52, No.7, 432-438 Summary of the Invention [Problem to be solved by the invention]

[0008] In providing ERG-containing feed, we discovered that when plant materials are used, if we try to include a high concentration of ERG, the amount of plant material added becomes large, which can lead to feeding disorders. Therefore, we aim to provide plant-based ergothioneine-containing feed that can be used to raise farmed fish stably. [Means for solving the problem]

[0009] The present inventors have conducted extensive research in order to provide an ergothioneine-containing feed, and as a result, have developed a feed with a high ergothioneine content that does not cause feeding disorders in farmed fish by using a solid fermentation product of Aspergillus oryzae as a raw material, thereby arriving at the present invention. Thus, the present invention relates to: [1] Feed containing 0.001% or more ergothioneine and made from solid fermentation products of Aspergillus oryzae. [2] The feed according to Item 2, wherein the koji mold solid fermentation product contains 0.35 g or more of ergothioneine per 1 kg of the koji mold solid fermentation product. [3] The feed according to item 1 or 2, wherein the solid fermentation product of koji mold is blended in the feed so as to be 1 to 10% by mass. [4] The feed according to any one of items 1 to 3, which is for raising farmed fish. [5] The feed according to Item 4, wherein the farmed fish is farmed tuna fish. [6] A method for producing farmed fish, comprising raising farmed fish using the feed according to any one of items 1 to 5. [7] The production method according to Item 6, comprising feeding the feed according to any one of Items 1 to 5 within one month before landing. [8] Farmed fish produced by the production method described in item 6 or 7. [9] The farmed fish according to item 8, wherein the farmed fish is a farmed tuna fish. [Effects of the Invention]

[0010] By producing feed using a solid-state fermentation product of koji mold with a high ergothioneine content as a raw material, we have provided an ergothioneine-containing feed that does not cause eating disorders.Furthermore, farmed fish fed this feed have an increased ergothioneine content and improved color and taste. [Brief explanation of the drawings]

[0011] [Figure 1]Figure 1 is a graph showing the change in ergothioneine (ERG) content with respect to the number of fermentation days when fermented under fermentation conditions that highly enrich ERG in Aspergillus oryzae solid fermented products using Aspergillus oryzae. [Figure 2] Figure 2 is a graph showing the change in the moisture content of the Aspergillus oryzae solid fermented product during fermentation. [Figure 3] Figure 3 is a graph showing the ERG content in the fish body of farmed fish fed with feed using the ERG - rich Aspergillus oryzae solid fermented product as a raw material.

Mode for Carrying Out the Invention

[0012] <ERG - containing Feed> The feed according to an embodiment of the present disclosure contains ergothioneine. More specifically, such feed contains 0.001% to 0.1% of ergothioneine by dry weight. Such feed uses the ERG - rich Aspergillus oryzae solid fermented product as a raw material. The ERG - rich Aspergillus oryzae solid fermented product can be produced by mixing 1% to 50% into a feed such as a commonly used moist pellet. The upper limit of the blending ratio of the ERG - rich Aspergillus oryzae solid fermented product can be 30%, 20%, or 10% from the perspective of not inhibiting feeding. The lower limit of the blending of the ERG - rich Aspergillus oryzae solid fermented product can be 1%, 5%, or 10% from the perspective of increasing the ergothioneine content. Raw materials other than the ERG - rich Aspergillus oryzae solid fermented product in the ERG - containing feed include raw materials used in commonly used moist pellets. As an example, fish meal and fish oil are mentioned. The ERG in the ERG - containing feed usually comes from the ERG - rich Aspergillus oryzae solid fermented product. More preferably, the ERG - containing feed of the present invention does not contain added ERG and / or ERG derived from mushrooms. A sample containing 0.001% to 0.1% of ergothioneine by dry weight using the ERG - rich Aspergillus oryzae solid fermented product as a raw material is specifically referred to as an ERG - rich Aspergillus - containing feed.

[0013] The ERG-containing feed is a feed for fish. By feeding and culturing with a feed containing a high-ERG koji, a cultured product in which ergothioneine is accumulated can be produced. The edible part of the cultured fish fed with the high-ERG koji-containing feed is less likely to change color, has a less likely to decline in taste, and has a high product value. In addition, the cultured fish containing ergothioneine is excellent in nutritional value in that it can ingest ergothioneine, which is an antioxidant. Therefore, the cultured fish containing ergothioneine cultured by feeding with an ERG-containing feed can also be used as a food with functional labeling. As such functional labeling, functions such as the elastase inhibitory action of ergothioneine, the beauty or whitening action based on the tyrosinase inhibitory action, the preventive action against lifestyle-related diseases based on the production of lipid peroxide, and the preventive action against dementia and Alzheimer's disease based on the removal of reactive oxygen can be displayed.

[0014] <Solid fermented product of high-ERG koji mold> The solid fermentation of high-ERG koji mold means a solid fermented product of koji mold produced by the method for increasing the ERG content in koji detailed below. The solid fermented product of high-ERG koji mold has an ERG content increased by 5 times or more, preferably 10 times or more, more preferably 20 times or more, still more preferably 50 times or more, and even more preferably 100 times or more, compared with the case of fermenting under normal fermentation conditions, for example, when the moisture content of the solid fermented product of koji mold is 25% or less. As an example, the solid fermented product of high-ERG koji mold contains ERG of 0.35 g or more per 1 kg of the solid fermented product of koji mold, preferably 0.4 g or more per 1 kg of the solid fermented product of koji mold, more preferably 0.5 g or more per 1 kg of the solid fermented product of koji mold, still more preferably 0.8 g or more per 1 kg of the solid fermented product of koji mold, and even more preferably 1.0 g or more per 1 kg of the solid fermented product of koji mold. The ERG contained in the solid fermented product of high-ERG koji mold of the present disclosure is produced by koji mold and is not added or concentrated. The solid fermented product of high-ERG koji mold is identified only by its manufacturing process, and it is impossible or impractical to specify it by the components and characteristics of the produced solid fermented product of high-ERG koji mold.

[0015] <Method for increasing ERG content> The method for increasing the ERG content according to one embodiment of the present disclosure refers to a method for solid-state fermentation of koji mold under fermentation conditions that increase the ERG content in the koji mold solid-state fermentation product, as described in detail below. The method for increasing the ERG content refers to a method for producing a koji mold solid-state fermentation product having an increased ERG content compared to a koji mold solid-state fermentation product produced using raw materials and under normal fermentation conditions.

[0016] To achieve a high ERG content in a koji mold solid-fermentation product, it is important to control the initial moisture content of the mixture of solid medium and koji mold and the moisture content during fermentation for at least four days. More specifically, it is necessary to maintain the moisture content of the mixture of solid medium and koji mold at 25% or higher even after the fourth day of fermentation. If the moisture content of the mixture of solid medium and koji mold during fermentation is less than 25%, the ERG content in the koji mold solid-fermentation product cannot be increased. Therefore, in one embodiment of the present disclosure, a method for producing a koji mold solid-fermentation product with a high ERG content is characterized in that the moisture content of the mixture is maintained at 25% or higher throughout the fermentation process during the fermentation process, in which the solid medium and koji mold are mixed and fermented. Furthermore, heat may be generated at the beginning of fermentation, leading to rapid moisture loss. Therefore, considering the fermentation period and process, if the initial moisture content of the mixture of solid medium and koji mold at the start of culture is less than 45%, it is difficult to maintain the moisture content of the fermentation product at 25% or higher during fermentation ( FIG. 2 ). Therefore, a method for producing a solid fermentation product of koji mold with a high ERG content according to one embodiment of the present disclosure may include a step of adjusting the initial moisture content of the mixture of solid medium and koji mold to 45% or more.

[0017] The ERG-rich koji mold solid fermentation product is prepared by fermenting a conventional solid medium for culturing koji mold. Such a solid medium preferably contains 10% or more protein in the solid content. As raw materials for such a solid medium, beans, fish, meat, algae, and processed products thereof containing 20% ​​or more protein can be used. Examples of processed products containing 20% ​​or more protein include defatted soybeans, fish meal, meat meal, and spirulina powder. It is more preferable that the solid medium of the present invention contains raw materials that have been puffed. The solid medium can be prepared by steaming or simmering the above-mentioned raw materials in boiling water, and optionally crushing them.

[0018] Other fermentation conditions may be those typically used in this technical field. For example, the initial pH of the medium is adjusted to 5 to 10. The fermentation temperature is set to 20 to 40°C, and the fermentation time is 4 days or longer, preferably 4 to 10 days, preferably 5 to 7 days, and more preferably 6 to 7 days. From the viewpoint of maintaining the moisture content of the koji mold solid-fermentation product during fermentation, it is preferable to culture under high humidity, and humidity can be adjusted to control the moisture content of the koji mold solid-fermentation product. Furthermore, since the fermentation is a long-term fermentation of 4 days or longer and involves a high moisture content, it is desirable to carry out the fermentation in an environment that prevents the growth of unwanted bacteria. Containers that allow for aseptic culture, such as a Yamazaki-type koji-making apparatus or a drum koji-making apparatus, may also be used.

[0019] As an example, when Aspergillus oryzae RIB326, a representative strain of koji mold, is used, and when an ERG-rich koji mold solid fermentation product is produced by the production method of the present invention, it is possible to produce an ERG-rich koji mold solid fermentation product containing 0.35 g ERG / 1 kg or more of koji mold solid fermentation product, preferably 0.4 g ERG / 1 kg or more of koji mold solid fermentation product, more preferably 0.5 g ERG / 1 kg or more of koji mold solid fermentation product, even more preferably 0.8 g ERG / 1 kg or more of koji mold solid fermentation product, and even more preferably 1.0 g ERG / 1 kg or more of koji mold solid fermentation product ( FIG. 1 ).

[0020] <Koji mold> Any fungus belonging to the genus Aspergillus can be used as the koji mold. Examples include Aspergillus oryzae, Aspergillus sojae, Aspergillus niger, Aspergillus luchuensis, and Aspergillus tamarii. Examples of koji mold strains that can be used include publicly available strains such as Aspergillus oryzae RIB326, strains contained in koji starters commercially available from koji makers, and strains isolated from food and beverage production environments such as sake and soy sauce breweries.

[0021] In addition, as the Aspergillus koji, a wild strain may be used, or a mutant strain with high ERG production may be further used by using a general mutagenesis method. Examples of the mutagenesis method include irradiation with ultraviolet rays (UV) or X-rays that physically damage DNA to introduce mutations, and treatment with alkylating agents such as N-methyl-N'-nitro-N-nitrosoguanidine (NTG) or ethyl methanesulfonate (EMS) that chemically damage DNA to introduce mutations. From the perspective of food production, it is preferable to use non-genetically modified strains. The Aspergillus koji may be one obtained by culturing Aspergillus koji in a medium, or one obtained by culturing Aspergillus koji, allowing spores to sufficiently grow, and drying them. It may be dried together with the raw material, or only the spores may be recovered.

[0022] <Method for analyzing ERG> The method for extracting ERG from the Aspergillus koji solid fermented product with high ERG content or the feed containing ERG can be carried out using methods well known in the art. The extraction solvent is not particularly limited as long as ERG can be dissolved therein, and examples thereof include organic solvents such as methanol, ethanol, isopropanol, and acetone; aqueous organic solvents obtained by mixing these organic solvents with water; water, warm water, and hot water. After adding the solvent, ERG can be extracted while appropriately applying a crushing treatment. The temperature of the extraction solvent can be set within the range from room temperature to 100°C.

[0023] As an embodiment of the method for extracting ERG, for example, a suspension prepared by adding the Aspergillus koji solid fermented product with high ERG content to water is subjected to a heating treatment such as 98 to 100°C for 15 minutes, and then the supernatant is recovered by centrifugation. Next, the recovered supernatant is filtered to remove insoluble matters. In addition, the heated suspension may be filtered without being subjected to centrifugation.

[0024] Instead of the above-mentioned heating treatment, the cells may be subjected to disruption treatment such as disrupting the cells using disruption means such as an ultrasonic disrupter, French press, Dynomill, or mortar; dissolving the cell walls of the cells using a cell wall-lytic enzyme such as Yatalase; or dissolving the cells using a surfactant such as SDS or Triton X-100. These methods may be used alone or in combination.

[0025] The resulting extract can be subjected to purification processes such as centrifugation, filter filtration, ultrafiltration, gel filtration, separation based on solubility differences, solvent extraction, chromatography (adsorption chromatography, hydrophobic chromatography, cation exchange chromatography, anion exchange chromatography, reverse phase chromatography, etc.), crystallization, activated carbon treatment, membrane treatment, etc. to purify ERG.

[0026] The qualitative or quantitative analysis of ERG is not particularly limited and can be performed, for example, by HPLC, etc. HPLC separation conditions can be appropriately selected by those skilled in the art, and can be performed, for example, under the conditions described in the Examples below.

[0027] <How farmed fish are produced> A method for producing cultured fish according to one embodiment of the present disclosure includes raising cultured fish using an ERG-containing feed. The method for producing cultured fish can also be simply referred to as a rearing method. Cultured fish raised and produced according to the method for producing cultured fish are referred to as cultured fish according to one embodiment of the present disclosure. For example, the ERG-containing feed is continuously fed at least 10 times. Feeding can be a satiation feeding once a day during normal times and a satiation feeding once every two days during winter. The ERG-containing feed can be fed at any timing, but from the viewpoint of improving taste, it is preferable to feed the fish with the ERG-containing feed for a feeding period before landing. More specifically, the feeding period is within six months, for example, within three months, within one month, within two weeks, within 12 days, or within 10 days. From the viewpoint of exerting a sufficient effect of improving color and / or taste, the feeding can be for a period of several days or more, for example, within 10 days. The water temperature during the rearing period is selected appropriately depending on the fish species, but as an example, it is set to 10°C to 32°C for cultivating tuna.

[0028] Any tuna species may be cultivated, but as an example, tuna weighing less than 40 kg and less than four years old are desirable. Farmed tuna weighing less than 40 kg and less than four years old generally have a stronger sour taste than farmed tuna fish grown for four years or more, making them unsuitable for consumption. On the other hand, by providing a feeding period with an ergothioneine-rich feed before landing, the ergothioneine content in the fish can be increased (Figure 3) and the sourness can be reduced (Example 3). The longer the feeding period with a feed containing koji with a high ERG content before landing, the more the ergothioneine content can be increased and the more the sourness can be reduced in farmed tuna fish, particularly farmed fish less than four years old. The increase in ergothioneine content varies depending on the ERG content of the feed containing koji with a high ERG content or the feeding period. As an example, in farmed fish fed a feed containing koji with a high ERG content, the ERG content increases by 10% or more, preferably 20% or more, more preferably 30% or more, and even more preferably 50% or more compared to a control fed a feed not containing koji with a high ERG content.

[0029] Furthermore, shortening the farming period before landing reduces the risk of devastating damage to farmed tuna fish caused by red tides and other factors. In this rearing method, as long as the fish are fed the ERG-rich feed throughout the above-mentioned rearing period before landing, there may be a period during which other feed is fed. Examples of other feed include live feed (horse mackerel, mackerel, etc.) and moist pellets.

[0030] <Farmed fish> In one embodiment of the present disclosure, the farmed fish may be any fish species that can be farmed. As an example, it is preferable to use the feed as feed for tunas, yellowtails, sea bream, pufferfish, salmon, trout, flounder, and flatfish. Examples of farmed tunas include the Thunnus family and the Bonito family. Examples of the Thunnus family include the Thunnus genus, the Bonito genus, the Scomber genus, and the Bonito genus, and examples of the Bonito family include the Dogtooth Thunnus genus and the Bonito genus. Examples of tunas include albacore, bluefin tuna, southern bluefin tuna, Atlantic bluefin tuna, Atlantic bluefin tuna, yellowfin tuna, bigeye tuna, and longfin tuna of the genus Thunnus, skipjack tuna of the genus Skipjack tuna, flathead tuna and frigate tuna of the genus Bonito, and bigeye tuna of the genus Sparrut, and skipjack tuna of the genus Bonito, or albacore, bluefin tuna, southern bluefin tuna, Atlantic bluefin tuna, yellowfin tuna, bigeye tuna, longfin tuna, skipjack tuna, and skipjack tuna. Preferred examples include albacore, bluefin tuna, Atlantic bluefin tuna, Atlantic bluefin tuna, yellowfin tuna, bigeye tuna, longfin tuna, skipjack tuna, and skipjack tuna.

[0031] <Method of manufacturing edible parts> A method for producing edible parts according to one embodiment of the present disclosure includes preparing farmed tuna fish obtained by the breeding method of the above-described embodiment, harvesting edible parts from the prepared farmed tuna fish, and placing the edible parts in a container, and may include other steps as necessary.

[0032] Examples of processed forms include the so-called headless form, in which the head and tail have been removed from farmed tuna fish, and the so-called loin form, in which the headless form is divided into left and right halves and dorsal and ventral sides and cut into quarters.

[0033] Farmed tuna fish and their edible parts can also be used as animal feed for livestock such as cows, pigs, and chickens, other farmed fish, and pet food.

[0034] All documents referred to in this disclosure are incorporated herein by reference in their entirety. In this disclosure, % means % by weight unless otherwise specified.

[0035] The following examples of the present invention are for illustrative purposes only and do not limit the technical scope of the present invention. The technical scope of the present invention is limited only by the claims. The present invention may be modified, for example, by adding, deleting, or substituting components of the present invention, provided that the modifications do not depart from the spirit of the present invention. [Example]

[0036] Example 1: Production of ERG-rich koji mold solid fermentation product using defatted soybeans as a medium 640 g of puffed defatted soybeans (protein content: approximately 48%) were placed in a plastic bag, and 480 ml of boiling water was added and steamed (protein content of the solid medium after steaming with hot water: approximately 27%). After cooling to room temperature, 2.4 g of Aspergillus oryzae RIB326 seed culture (wheat bran culture) was added and mixed thoroughly. The mixture was then flattened onto a lid. Fermentation was carried out at 95% humidity and 32°C. When the temperature of the koji mold solid-fermentation mixture reached 40°C, the room temperature was changed to 25°C, humidity control was discontinued, and fermentation continued for 7 days to obtain a koji mold solid-fermentation mixture with a high ERG content. The koji mold solid-fermentation mixture was weighed on days 1, 3, 4, and 7, and the moisture content was calculated (Figure 2). In addition, aliquots of the koji mold solid-fermentation mixture were taken on days 1, 2, 3, and 6.

[0037] Example 2: Method for analyzing ERG (1) Extraction of ERG Five grams of ERG-rich koji mold solid-state fermentation product was weighed out, 75% ethanol was added, and the product was then crushed and left at room temperature for one day to extract ERG from the ERG-rich koji mold solid-state fermentation product. The ERG content was measured under the analytical conditions described below, and the ERG content per kg of ERG-rich koji mold solid-state fermentation product was found to be 1.1 g. Similarly, the ERG content was measured for the fermentation product on days 1, 2, 3, and 6 after the start of fermentation, and the results are shown in a graph (Figure 1). As a reference example, ERG was similarly extracted from Miyako Koji Square (manufactured by Isesosha Co., Ltd.), Rice Koji H (manufactured by Kose Foods Co., Ltd.), and Rice Koji S (manufactured by Kose Foods Co., Ltd.), and the ERG content was measured under the following analytical conditions. The ergothioneine content of each was as follows: [Table 1]

[0038] (2)LCMS analysis conditions Analyzer: UPLC CQ micro;Waters UPLC Column: 2.5 HILIC 3.0mm l.D. x 150mm Solvent A: Acetonitrile Solvent B: 5mM ammonium acetate / H2O Flow rate: 0.5 ml / min 80% solvent A Inject: 2μL mass spectrometer ESI: ES+ Cone V: 21V Capillary V: 4.5kV Source temperature: 120℃ Desolvation temperature:400℃ MS Scan mode

[0039] (3) Ergothioneine analysis conditions by LC-MS / MS Analyzer: UPLC CQ micro;Waters UPLC Column: 2.5 HILIC 3.0 mm l.D. x 150 mm Solvent A: 0.1% formic acid / acetonitrile Solvent B: 0.1% formic acid / H2O Flow rate: 0.5ml / min 80%A Inject: 2μL mass spectrometer ESI: ES+ Cone V: 21V Capillary V: 4.5kV Source temperature: 120℃ Desolvation temperature:400℃ Collision energy: 11V Trace: m / z 230.1>186.1 Collision energy: 20V Trace: m / z 230.1>127.0

[0040] Example 3: Raising farmed tuna fish with ERG-containing feed (1) Production of ERG-containing feed The ERG-rich koji mold solid-fermentation product produced in Example 1 was mixed with moist pellet feed (sold by:) at an average concentration of 2.69% (2.43-3.05%) to produce an ERG-containing feed. The ERG content of the ERG-containing feed was 0.011% by dry weight.

[0041] (2) Rearing method The ERG-containing diet was fed to 3-year-old tuna once a day for 12 days, a total of 12 times. In the control group, moist pellet feed containing no ERG-rich koji was fed to three-year-old tuna fish for the same period and frequency.

[0042] (3) Fish body measurements Three fish were caught by fishing from the test area and two from the control area. Immediately after being caught, the tuna was bled, nerve-killed, and the internal organs and gills were removed on board the boat, and it was then stored in ice water until it was processed into loins at the processing plant. The tuna taken were treated as described above, and in the test area, individual 1 had a fish weight of 31.9 kg and a fork length of 119 cm, individual 2 had a fish weight of 30.6 kg and a fork length of 118 cm, and individual 3 had a fish weight of 34.7 kg and a fork length of 126 cm; in the control area, individual 1 had a fish weight of 29.4 kg and a fork length of 116 cm, and individual 2 had a fish weight of 34.6 kg and a fork length of 122 cm. The fish bodies stored in ice water were processed into loins and transported and stored on ice until sensory evaluation.

[0043] (4) Sensory evaluation The sensory evaluation was carried out by 24 in-house selected and trained evaluators, using analytical and preference-based evaluations. Each item in the sensory evaluation was scored using absolute evaluations. Evaluators were trained to evaluate each item according to a set of standards, and scored sourness on a 5-point scale from 0 to 1, 2, 3, and 4, with increasing sourness, and hardness on a 7-point scale from soft to hard, with -3, -2, -1, 0, +1, +2, and +3.

[0044] As a result of the sensory evaluation, the test group showed a significant decrease in sourness (P<0.05) compared to the control group. There was also a significant tendency for hardness (P=0.08), but the test group showed a decrease compared to the control group (Table 2). [Table 2]

[0045] In the sensory evaluation (preference-based evaluation), the taste was evaluated comprehensively and the evaluation was scored as an "overall evaluation" (Table 3). [Table 3]

[0046] (5) Measurement of ERG levels in tuna The fish from the test and control groups were weighed, 75% ethanol was added, and the fish were crushed and left at room temperature for one day to extract ERG. The ERG content was measured under the following analytical conditions, and the results are shown in a graph (Figure 3) for ERG content per gram of fish.

[0047] (5-1)LCMS analysis conditions Analyzer: UPLC CQ micro;Waters UPLC Column: 2.5 HILIC 3.0mm l.D. x 150mm Solvent A: Acetonitrile Solvent B: 5mM ammonium acetate / H2O Flow rate: 0.5 ml / min 80% solvent A Inject: 2μL mass spectrometer ESI: ES+ Cone V: 21V Capillary V: 4.5kV Source temperature: 120℃ Desolvation temperature:400℃ MS Scan mode

[0048] (5-2) Ergothioneine Analysis Conditions by LC-MS / MS Analyzer: UPLC CQ micro;Waters UPLC Column: 2.5 HILIC 3.0 mm l.D. x 150 mm Solvent A: 0.1% formic acid / acetonitrile Solvent B: 0.1% formic acid / H2O Flow rate: 0.5ml / min 80%A Inject: 2μL mass spectrometer ESI: ES+ Cone V: 21V Capillary V: 4.5kV Source temperature: 120℃ Desolvation temperature:400℃ Collision energy: 11V Trace: m / z 230.1>186.1 Collision energy:20V Trace: m / z 230.1>127.0

Claims

1. A feed containing 0.001% or more of ergothioneine and made from a solid fermentation product of koji mold, wherein the solid fermentation product of koji mold contains 0.35 g or more of ergothioneine per kg of the solid fermentation product of koji mold.

2. The feed according to claim 1, wherein the solid fermentation product of koji mold is blended in the feed so as to be 1 to 10% by mass.

3. The feed according to claim 1 or 2, which is for raising farmed fish.

4. The feed according to claim 3, wherein the farmed fish is farmed tuna fish.

5. A method for producing farmed fish, comprising raising farmed fish using the feed according to any one of claims 1 to 4.

6. The method according to claim 5, comprising a step of feeding the feed according to any one of claims 1 to 4 within one month before landing.

7. A farmed fish produced by the production method according to claim 5 or 6.

8. The farmed fish according to claim 7, wherein the farmed fish is a farmed tuna fish.

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