【０００１】
【発明の属する利用分野】
本発明は水産養殖において利用される油脂を高含有する養魚用固形飼料に関する。
【０００２】
【従来の技術】
水産養殖における養魚用飼料はその生産性、環境問題から固形化が進み、更にその生産物の食味の問題等から油脂を高含有する養魚用飼料の開発が望まれている。通常使われている油脂は常温で液体であり、大量の油脂を固形飼料の成形前の飼料混合物中に添加すれば、成形時に圧力が加わり難く、得られる固形飼料の物性は脆く、耐久性は劣るものとなる。また、多量の油脂を成形後の固形飼料に添加すれば、貯蔵期間中に滲みや漏れが発生するとか、養殖魚に投与する際、水質を汚染させるなどの問題を引起す他、飼料製造工程においても輸送機、包装機を汚し、装置の故障原因となるなどの問題がある。
【０００３】
現在使用の油脂含量の高い養魚用固形飼料は脂肪含有量として、約２０〜３０％程度のものである。更にその比率を高めて欲しいとの要望もあるが、上記課題解決のため、例えば特開平３−１０８４５４は、油脂含有率が１０〜５０％の養魚用ドライペレットを製造する場合において、グリセリン脂肪酸エステル等を油脂に対し０．１〜１０％添加することを提案し、更に油脂としては硬化油も使用できるとしている。しかしながら、押出し成形する前の飼料混合物にグリセリン脂肪酸エステルと多量の油脂を添加することは、押出し成形の際、圧力がかからず成形性が悪く、壊れやすい固形飼料となることが知られている。
【０００４】
特表平９−５０２１０１は多孔質ペレット飼料に脂質とモノグリセリド、ジグリセリドなどの乳化剤またはナタネ調質油との混合物により結晶構造を形成させ、脂質を飼料中に保持させることが提案されている。しかし、このようにして得られた多孔質ペレットも、ある程度の油漏れの問題があることが知られている。
【０００５】
特表２００１−５２７４０５では、養魚飼料の主要原料に、通常の環境下で固体である脂質又は脂肪酸の添加物を添加混合し、プレコンディショニングを行った後、押出し成形したペレットに魚油など吸収させることで離油を防ぐことが提案されている。しかし、添加物を成形前に通常の環境下で固体である脂質又は脂肪酸の添加物を加え、成形後に魚油などの油を吸収させるものであるので、気温が高くなると油脂が滲み易くなる難点がある。また、原料コストが非常に高くなり、コスト削減のため、脂質又は脂肪酸等の添加剤の添加量を減らして得られるペレットでは、油の漏出を防げない事が判っている。
【０００６】
従来技術に従って製造される油脂を高含有する養魚用固形飼料の多くは、その物性が不満足であるか、または油脂が滲み易く又は油漏れが多く不経済であり、また水質汚染になるなどの問題がある。
【０００７】
【発明が解決しようとする課題】
本発明は油脂を高含有する養魚用固形飼料において、形状、物性がよく、油漏れ量が少ない高油脂含有の養魚用固形飼料およびその製造方法を提供することにある。
【０００８】
【課題を解決するための手段】
上記課題を解決するために本発明者が鋭意検討を行った結果、固形飼料の外側を常温で固まる性状を有する硬化油にて被覆することにより、形状、物性がよく、油漏れ量が少ない高油脂含有の養魚用固形飼料を得ることに成功し、本発明を完成するに至った。
【０００９】
すなわち本発明は油脂を高含有する養魚用固形飼料において、固形飼料の外側を常温で固まる性状を有する硬化油にて被覆してなる養魚用固形飼料であり、また硬化油が水素添加魚油、水素添加菜種油、水素添加大豆油、水素添加ヒマワリ油及び水素添加パーム油等である前記飼料である。
また、本発明は固形飼料に通常の油脂を添加後、更に硬化油を添加して固形飼料を被覆する養魚用固形飼料の製造方法であり、また、減圧下にて硬化油を添加して固形飼料を被覆する前記製造方法である。
【００１０】
本発明における油脂を高含有する養魚用固形飼料とは、脂肪分として飼料中１０〜４０％含有する飼料である。
また、固形飼料とはペレットミル、エキスパンダーとペレットミル、１軸または２軸のエクストルーダー等の成形機にて押出し成形された固形飼料をいい、ペレットまたは多孔性ペレットと言われる。押出し成形された固形飼料の嵩比重は約５５０〜７５０ｇ／Ｌであり、好ましくは５８０〜６８０ｇ／Ｌである。
【００１１】
本発明の養魚用固形飼料は通常次のような方法で製造される。
（１）飼料原料混合物に蒸気または水分を添加後成形機にて固形状に成形する。（２）この成形したものを乾燥した後、油脂を添加吸着させる。（３）更に、油脂を吸着した固形飼料に対し硬化油を添加し固形飼料を被覆する。
【００１２】
本発明で使用される油脂以外の原料としては魚粉、大豆油粕、小麦グルテン、コーングルテンミールなどの蛋白源、小麦粉、澱粉、加工澱粉など炭水化物・バインダー、ビタミン類、ミネラル類などの栄養成分が挙げられ、これらを適宜選択して使用する。
【００１３】
また、魚粉も油脂源となるが、本発明において油脂原料は通常３工程にて添加される。すなわち▲１▼成形時のプレコンディショナーでの添加、▲２▼次に成形、乾燥後に添加、▲３▼更に、硬化油を添加し被覆する。
【００１４】
成形時のプレコンディショナーでの添加および成形、乾燥後に添加する油脂としてはタラ肝油、イワシ油、イカ油、シシャモ油、ニシン油およびウグイ油のような魚油が挙げられ、これら油脂は単一でもよく、個々の油脂の混合物でもよい。通常プレコンディショナーでは飼料全体の３〜１５％（重量％）が添加され、更に成形、乾燥後に１０〜３０％程度添加される。これら油脂の添加量は対象とする魚種の栄養要求により適宜その必要量を選択できる。
【００１５】
本発明においては油脂を吸着させた上記固形飼料の外側に常温で固まる性状を有する硬化油を添加し、被覆させる。この際に使用する硬化油は上記したタラ肝油、イワシ油、イカ油、シシャモ油、ニシン油およびウグイ油のような魚油を水素添加して製造した硬化魚油および水素添加菜種油、水素添加大豆油、水素添加ヒマワリ油及び水素添加パーム油等を使用することが出来る。被覆する硬化油は通常の魚油、穀物油などを水素添加により製造したものであればよく、融点としては４０〜６５℃程度のものが望ましく、特に５０〜６０℃のものが好ましい。
添加量としては少ないと被覆効果が出ず、また量が多すぎると消化に難点があるので１〜５％の範囲が望ましい。
【００１６】
押出し成形された固形飼料への油脂添加については、押出し成形の直後に行う場合と、少し時間を経た後に行う場合とがある。油脂添加は混合、漬込み、噴霧、コーティング、その他など種々の手段によって実施できる。また、油脂および硬化油の添加は常圧下の回転ドラムで混合することでも可能であるが、加圧下あるいは減圧下でも可能であり、減圧下で添加すると固形飼料に油脂が十分に吸着または被覆されるので望ましい。
【００１７】
例えば押出し成形された固形飼料を減圧下に置き、同時あるいは続いて油脂と接触させる。この段階の圧力は１〜５０ｋＰａの間で、好ましくは１０〜３０ｋＰａである。固形飼料への油脂吸着時間は３０秒〜３０分、より好ましくは１〜５分である。減圧下で固形飼料に油脂を吸着させた後、圧力は常圧に戻される。
固形飼料により多くの油脂を吸着させる為に、油脂を添加する工程を２回以上反復してもよい。
【００１８】
本発明では、最終油脂添加工程において、常温で固まる性状を有する硬化油を添加するが、この硬化油は予め加温し、融解した後に使用する。減圧下で油脂を添加する場合、先ず、常温では固まらない通常の融点の油脂を減圧下で吸着させ、圧力を常圧に戻す間に高融点の硬化油を添加する方法をとることが出来る。また、減圧下の油脂添加を２回行う場合は、前の工程で使用した油脂より高い融点の硬化油を使用するのが望ましい。
【００１９】
油脂添加後はクーラーにより固形飼料の品温が下げられ、製品は包装、保管される。固形飼料外側の高融点の硬化油は常温に戻ると固体となり、プレコンディショナー等の前工程で添加した常温で液体の油脂を、固形飼料内部に閉じ込めた形となる。
【００２０】
本発明の養魚用固形飼料はブリ、タイ、ギンザケ、シマアジ、カンパチ、フグ、ウナギ、コイ、マスなどの養殖魚に給餌することが出来る。
【００２１】
【実施例】
以下に、実施例を示して本発明を具体的に説明するが、本発明はこれら実施例により制限されるものではない。
〔実施例１〕
表１に示す基本原料を配合粉砕して原料配合品を製造した。この原料配合品はウェンガー製２軸エクストルーダーＴＸ−１１５型を用いて、プレコンディショナーにて水分の調湿と表１に示す油脂添加を行い、２Ｔ／Ｈで押し出し成形した。得られた固形飼料は直径１６ｍｍ、長さ１４ｍｍで概ね円筒形だった。この押出された固形飼料は水分含量が約２２％であり、次に乾燥機を通過させ、水分量をほぼ１０％以下まで減少させた。この乾燥した固形飼料を減圧式油脂添加装置に投入し、まず２５ｋＰａ前後まで減圧し、次いで通常の魚油６％を添加した。
添加後、常圧に戻し固形飼料に魚油を完全に含浸させた後に、２回目の油脂添加において、７０℃に温めておいたパーム硬化油（融点５５〜６０℃）２％を添加し、次いで冷却して本発明の養魚用固形飼料を得た。
【００２２】
【表１】
【００２３】
〔実施例２〕
実施例１と同様にして得られた固形飼料を減圧式油脂添加装置にて２５ｋＰａ前後まで減圧し、固形飼料に魚油を５％添加し、その後実施例１と同様の方法にてパーム硬化油（融点５５〜６０℃）３％を添加し本発明の養魚用固形飼料を得た。
【００２４】
〔対照例〕
実施例１と同様にして得た固形飼料を減圧式油脂添加装置に投入し、２５ｋＰａ前後まで減圧した後、通常の液状魚油を８％添加し、硬化油を使用しない以外は実施例１と同様にして製造し、対照飼料を得た。
【００２５】
〔比較例１〕
実施例１と同様にして得た固形飼料を減圧式油脂添加装置に投入し、次いで魚油に対して乳化剤（グリセリンモノステレート）を５％加えた乳化剤混合魚油を固形飼料に対し８％添加し、実施例１と同様にして比較例１飼料を得た。
【００２６】
〔比較例２〕
表１に示す基本原料に乳化剤（グリセリンモノステレート）１％を加え、配合粉砕して原料配合品を製造した。次いで、実施例１と同様にして固形飼料を得た後、通常の液状魚油を８％添加して比較例２飼料を得た。
【００２７】
（結果）
各実施例飼料及び対照飼料、比較例飼料の油脂含量は表２に示す通りであった。また、各飼料の油漏れ量を次の方法で測定した。養魚用固形飼料を５個ずつ取り重量を測定する。各飼料を、濾紙を敷いた皿に取り、その上に２ｋｇの加重をかけた。皿を４０℃の恒温器中で一晩置いた後、濾紙の重量を測定し、その増加量を油漏れ量とし粗脂肪分に対する割合で算出した。測定結果は２表の通りである。本測定は実際の工場での保管条件（パレット３段積み重ね）の下部圧力を想定したものである。
【００２８】
【表２】
【００２９】
各飼料の粗脂肪含量は何れも２６％台であった。本発明による製造方法およびそれにより得られた養魚用固形飼料の油漏れ量は９．９〜１６％であり、対照飼料の２７．６％、比較飼料の２２．７〜２４．６％に比し格段と優れたものであった。油脂を高含有する養魚用固形飼料においてこのように低いレベルの油漏れは、従来の技術では達成できなかったものである。
【００３０】
〔実施例３〕
表３に示す基本原料を配合粉砕して原料配合品を製造した。この原料配合品をプレコンディショナーにて水分の調湿と表３に示す油脂添加を行い、次いでビューラー製２軸エクストルーダーＤＮＤＨ−１２５型を用い、２Ｔ／Ｈで押し出し成形した。得られた固形飼料は直径が１１ｍｍ、長さが１０ｍｍで概ね円筒形だった。この押出された固形飼料は水分含量が約２２％であり、次に乾燥機を通過させ、水分量が１０％以下とした。この乾燥した固形飼料を実施例１と同様な方法で表３に示す魚油１４％および硬化魚油（融点５５〜６０℃）２％を添加し、次いで冷却して本発明の養魚用固形飼料を得た。
【００３１】
【表３】
【００３２】
〔実施例４〕
実施例３と同様にして得られた固形飼料に魚油１３％と硬化魚油（融点５５〜６０℃）３％を実施例１と同様な方法で添加し、次いで冷却して本発明の養魚用固形飼料を得た。
【００３３】
〔比較例３〕
実施例３と同様にして得た固形飼料を減圧式油脂添加装置に投入し、次いで魚油１６％添加し、実施例１と同様にして比較例３飼料を得た。
【００３４】
〔比較例４〕
実施例３と同様にして得た固形飼料を減圧式油脂添加装置に投入し、次いでグリセリンモノステレートを５％配合した魚油を１６％添加し、実施例１と同様にして比較例４飼料を得た。
【００３５】
（結果）
実施例３、４飼料及び比較例３、４飼料の油脂含量は表４に示す通りであった。また、各飼料の油漏れ量を実施例１と同様な方法で測定した結果は表４の通りであった。各飼料の粗脂肪含量は２４．５〜２５．１％であった。また実施例３、４飼料の油漏れ量は３．５〜１０．８％であり、比較飼料の１８．７〜５３．５％に比し格段と優れたものであった。
【００３５】
【表４】
【００３６】
【発明の効果】
本発明により、油脂を高含有する養魚用固形飼料において、油漏れの程度が従来技術に比べ極端に少なくすることができたため、保管中や使用時に油脂のロスを極端に少なくでき、経済的で、かつ水質を汚さない養魚用固形飼料が提供される。[0001]
FIELD OF THE INVENTION
The present invention relates to a solid feed for fish farming containing a high content of oils and fats used in aquaculture.
[0002]
[Prior art]
The solidification of fish feed for aquaculture is progressing due to its productivity and environmental problems, and furthermore, the development of a fish feed with a high oil content is desired in view of the taste of the product. Generally used fats and oils are liquid at normal temperature, and if a large amount of fats and oils are added to the feed mixture before molding of the solid feed, pressure is hardly applied at the time of molding, the physical properties of the obtained solid feed are brittle, and the durability is low. Inferior. In addition, if a large amount of fats and oils are added to the solid feed after molding, bleeding and leakage may occur during the storage period, and when administered to farmed fish, it may cause problems such as contamination of water quality, and in addition, the feed production process However, there are also problems such as fouling of the transport machine and the packaging machine, which may cause a failure of the device.
[0003]
Currently used solid feeds for fish farming having a high oil and fat content have a fat content of about 20 to 30%. There is a demand that the ratio be further increased, but in order to solve the above-mentioned problems, for example, Japanese Patent Application Laid-Open No. 3-108454 discloses a method for producing glycerin fatty acid ester when producing dry pellets for fish farming having an oil content of 10 to 50%. It is proposed that 0.1 to 10% be added to fats and oils, and that hardened oils can be used as fats and oils. However, it is known that adding a glycerin fatty acid ester and a large amount of fats and oils to a feed mixture before extrusion molding does not apply pressure during extrusion molding, resulting in poor moldability and a fragile solid feed. .
[0004]
Japanese Patent Application Laid-Open No. 9-502101 proposes that a porous pellet feed is formed with a mixture of lipid and an emulsifier such as monoglyceride or diglyceride or a rapeseed refined oil to form a crystal structure, thereby retaining the lipid in the feed. However, it is known that the porous pellets thus obtained also have some problem of oil leakage.
[0005]
In Japanese Patent Application Laid-Open No. 2001-527405, the main raw material of fish feed is mixed with an additive of lipid or fatty acid which is solid under a normal environment, and after preconditioning, extruded pellets are made to absorb fish oil or the like. It has been proposed to prevent oil separation. However, prior to molding, the additive is a solid lipid or fatty acid additive under a normal environment, and the oil or fat such as fish oil is absorbed after molding. is there. Further, it has been found that the raw material cost becomes extremely high, and in order to reduce the cost, pellets obtained by reducing the amount of additives such as lipids or fatty acids cannot prevent oil leakage.
[0006]
Many of the solid feeds for fish farming which contain a high content of fats and oils produced according to the prior art have problems such as unsatisfactory physical properties, liability of oils and fats to leak or oil leakage and uneconomics, and water pollution. There is.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a solid feed for fish farming containing high fats and oils, which has good shape, physical properties and a small amount of oil leakage, and a method for producing the same.
[0008]
[Means for Solving the Problems]
As a result of intensive studies by the present inventors to solve the above problems, the outer surface of the solid feed is coated with a hardened oil having a property of solidifying at room temperature, so that the shape, physical properties are good, and the amount of oil leakage is small. The inventors succeeded in obtaining a solid feed for fish culture containing oils and fats, and completed the present invention.
[0009]
That is, the present invention is a solid feed for fish farming containing a high content of oils and fats, wherein the solid feed for fish farming is formed by coating the outside of the solid feed with hardened oil having a property of hardening at room temperature, and the hardened oil is hydrogenated fish oil, hydrogen The above feed, which is added rapeseed oil, hydrogenated soybean oil, hydrogenated sunflower oil, hydrogenated palm oil and the like.
Further, the present invention is a method for producing a solid feed for fish farming in which a solid fat is added to a solid feed and then the hardened oil is further added to coat the solid feed, and the hardened oil is added under reduced pressure to solidify the solid feed. The above-described production method for coating a feed.
[0010]
In the present invention, the solid feed for fish farming containing a high content of fats and oils is a feed containing 10 to 40% as fat in the feed.
The solid feed is a solid feed extruded by a molding machine such as a pellet mill, an expander and a pellet mill, a single-screw or twin-screw extruder, and is referred to as a pellet or a porous pellet. The bulk specific gravity of the extruded solid feed is about 550 to 750 g / L, preferably 580 to 680 g / L.
[0011]
The solid feed for fish culture of the present invention is usually produced by the following method.
(1) After adding steam or moisture to the feed raw material mixture, the mixture is molded into a solid by a molding machine. (2) After drying this molded product, fats and oils are added and adsorbed. (3) Further, a hardened oil is added to the solid feed to which the fat or oil has been adsorbed to coat the solid feed.
[0012]
Raw materials other than the fats and oils used in the present invention include fish meal, soybean oil meal, wheat gluten, protein sources such as corn gluten meal, wheat flour, starch, carbohydrates and binders such as processed starch, vitamins, and nutrients such as minerals. These are appropriately selected and used.
[0013]
Fish meal is also a source of fats and oils, but in the present invention, fat and oil raw materials are usually added in three steps. That is, (1) addition by a pre-conditioner at the time of molding; (2) addition after molding and drying; and (3) further, a hardened oil is added to cover.
[0014]
Addition and shaping with a preconditioner at the time of shaping, shaping, and oils to be added after drying include fish oils such as cod liver oil, sardine oil, squid oil, shishamo oil, herring oil and Japanese dace oil, and these oils may be used alone. Or a mixture of individual fats and oils. Usually, in a preconditioner, 3 to 15% (wt%) of the whole feed is added, and after forming and drying, about 10 to 30% is added. The required amount of these fats and oils can be appropriately selected according to the nutritional requirements of the target fish species.
[0015]
In the present invention, a hardened oil having a property of hardening at room temperature is added to the outside of the solid feed on which the fats and oils are adsorbed, and coated. The hardened oil used at this time is the above-mentioned cod liver oil, sardine oil, squid oil, shishamo oil, herring oil and hydrogenated fish oil such as herring oil and hydrogenated fish oil and hydrogenated rapeseed oil, hydrogenated soybean oil, hydrogenated soybean oil, Hydrogenated sunflower oil and hydrogenated palm oil can be used. The hardened oil to be coated may be one produced by hydrogenating ordinary fish oil, cereal oil or the like, and has a melting point of preferably about 40 to 65 ° C, particularly preferably 50 to 60 ° C.
When the amount is small, the coating effect is not obtained, and when the amount is too large, digestion is difficult.
[0016]
The addition of the fat or oil to the extruded solid feed may be performed immediately after the extrusion or may be performed after a short time. Fats and oils can be added by various means such as mixing, dipping, spraying, coating and the like. The addition of fats and oils and hardened oils is also possible by mixing with a rotating drum under normal pressure, but it is also possible under pressure or under reduced pressure.When added under reduced pressure, the fat or oil is sufficiently adsorbed or coated on the solid feed. So desirable.
[0017]
For example, the extruded solid feed is placed under reduced pressure and contacted with the fat or oil simultaneously or subsequently. The pressure at this stage is between 1 and 50 kPa, preferably between 10 and 30 kPa. The oil and fat adsorption time on the solid feed is 30 seconds to 30 minutes, more preferably 1 to 5 minutes. After adsorbing the fats and oils on the solid feed under reduced pressure, the pressure is returned to normal pressure.
The step of adding fats and oils may be repeated two or more times in order to adsorb more fats and oils to the solid feed.
[0018]
In the present invention, in the final fat / oil adding step, a hardened oil having a property of hardening at room temperature is added. This hardened oil is used after being heated and melted in advance. In the case of adding fats and oils under reduced pressure, a method of first adsorbing fats and oils having a normal melting point which does not solidify at normal temperature under reduced pressure, and adding a high-melting hardened oil while returning the pressure to normal pressure can be adopted. When the fat or oil is added twice under reduced pressure, it is desirable to use a hardened oil having a higher melting point than the fat or oil used in the previous step.
[0019]
After adding the fat, the temperature of the solid feed is lowered by a cooler, and the product is packaged and stored. The high-melting hardened oil on the outside of the solid feed becomes solid when it returns to normal temperature, and becomes a form in which the oil and fat added at the normal temperature and added in the previous step such as the preconditioner is confined inside the solid feed.
[0020]
The solid feed for fish culture of the present invention can be fed to farmed fish such as yellowtail, thailand, coho salmon, striped horse mackerel, amberjack, puffer fish, eel, carp and trout.
[0021]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.
[Example 1]
The basic raw materials shown in Table 1 were blended and pulverized to produce raw material blends. This raw material mixture was extruded at 2 T / H using a Wenger twin-screw extruder model TX-115, moisture conditioning and addition of fats and oils shown in Table 1 by a preconditioner. The obtained solid feed was 16 mm in diameter and 14 mm in length and was substantially cylindrical. The extruded chow had a moisture content of about 22% and was then passed through a dryer to reduce the moisture content to approximately 10% or less. The dried solid feed was charged into a reduced-pressure oil / fat addition device, and the pressure was first reduced to about 25 kPa, and then 6% of normal fish oil was added.
After the addition, the pressure was returned to normal pressure, and the solid feed was completely impregnated with fish oil. Then, in the second addition of fats and oils, 2% of palm hardened oil (melting point 55 to 60 ° C.) warmed to 70 ° C. was added. After cooling, the solid feed for fish culture of the present invention was obtained.
[0022]
[Table 1]
[Example 2]
The solid feed obtained in the same manner as in Example 1 was evacuated to about 25 kPa with a reduced-pressure oil / fat addition device, and 5% of fish oil was added to the solid feed. (Melting point: 55-60 ° C.) 3% was added to obtain a solid feed for fish farming of the present invention.
[0024]
(Control example)
The solid feed obtained in the same manner as in Example 1 was put into a reduced-pressure oil / fat addition apparatus, and the pressure was reduced to about 25 kPa. Then, 8% of ordinary liquid fish oil was added, and the same procedure as in Example 1 was carried out except that no hardened oil was used. And a control feed was obtained.
[0025]
[Comparative Example 1]
The solid feed obtained in the same manner as in Example 1 was charged into a reduced-pressure oil / fat addition device, and then 8% of the emulsifier mixed fish oil obtained by adding 5% of an emulsifier (glycerin monosterate) to fish oil was added to the solid feed. In the same manner as in Example 1, a feed for Comparative Example 1 was obtained.
[0026]
[Comparative Example 2]
An emulsifier (glycerin monosterate) (1%) was added to the basic raw materials shown in Table 1, and blended and pulverized to produce a raw material blended product. Next, after obtaining a solid feed in the same manner as in Example 1, 8% of ordinary liquid fish oil was added to obtain a feed for Comparative Example 2.
[0027]
(result)
The fats and oils content of the feed of each Example, the control feed and the feed of Comparative Example were as shown in Table 2. Further, the amount of oil leak of each feed was measured by the following method. Five solid feeds for fish farming are measured and weighed. Each feed was placed on a dish covered with filter paper and overlaid with a 2 kg weight. After the dish was placed in a thermostat at 40 ° C. overnight, the weight of the filter paper was measured, and the increased amount was defined as the amount of oil leakage and calculated by the ratio to the crude fat content. The measurement results are shown in Table 2. This measurement assumes the lower pressure under the actual storage conditions in the factory (three pallets stacked).
[0028]
[Table 2]
The crude fat content of each feed was of the order of 26%. The oil leakage of the production method according to the present invention and the solid feed for fish culture obtained thereby is 9.9 to 16%, compared to 27.6% of the control feed and 22.7 to 24.6% of the comparative feed. It was much better. Such low levels of oil spills in fish farming solids with a high fat content have not been achievable with conventional techniques.
[0030]
[Example 3]
The basic raw materials shown in Table 3 were blended and pulverized to produce raw material blends. This raw material mixture was subjected to moisture conditioning and the addition of fats and oils shown in Table 3 by a preconditioner, and then extruded at 2 T / H using a Buhler twin-screw extruder DNDH-125. The obtained solid feed was 11 mm in diameter and 10 mm in length and was substantially cylindrical. The extruded solid feed had a moisture content of about 22% and was then passed through a dryer to a moisture content of 10% or less. To the dried solid feed, 14% of fish oil and 2% of hardened fish oil (melting point: 55 to 60 ° C) shown in Table 3 were added in the same manner as in Example 1, and then cooled to obtain the solid feed for fish culture of the present invention. Was.
[0031]
[Table 3]
[Example 4]
To the solid feed obtained in the same manner as in Example 3, 13% of fish oil and 3% of hardened fish oil (melting point: 55 to 60 ° C) were added in the same manner as in Example 1, and then cooled to obtain a solid for fish culture of the present invention. Feed was obtained.
[0033]
[Comparative Example 3]
The solid feed obtained in the same manner as in Example 3 was charged into a reduced-pressure oil / fat addition apparatus, and then 16% of fish oil was added. In the same manner as in Example 1, a feed for Comparative Example 3 was obtained.
[0034]
[Comparative Example 4]
The solid feed obtained in the same manner as in Example 3 was charged into a reduced-pressure oil / fat addition device, and then 16% fish oil containing 5% glycerin monosterate was added. Obtained.
[0035]
(result)
The fat content of the feeds of Examples 3 and 4 and Comparative Examples 3 and 4 was as shown in Table 4. Table 4 shows the results of measuring the amount of oil leakage of each feed in the same manner as in Example 1. The crude fat content of each feed was 24.5 to 25.1%. In addition, the amount of oil leakage of the feeds of Examples 3 and 4 was 3.5 to 10.8%, which was remarkably superior to 18.7 to 53.5% of the comparative feed.
[0035]
[Table 4]
【The invention's effect】
According to the present invention, in a solid feed for fish farming containing a high content of fats and oils, the degree of oil leakage can be extremely reduced as compared with the prior art, so that the loss of fats and oils during storage and use can be extremely reduced, and it is economical. And a solid feed for fish farming that does not pollute water quality.