JPH0439976B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing dry pellets as fish feed. [Conventional technology] Conventional use as fish feed for saltwater fish such as yellowtail, sea bream, salmon, flounder, and striped horse mackerel, freshwater fish such as carp, trout, sweetfish, eel, yamame, tilapia, and catfish, or crustaceans such as kuruma prawn and prawn. For example, there are live baits such as sardines, horse mackerel, and mackerel, moist pellets made by blending and granulating raw bait with horse mackerel, and dry pellets made by granulating fish meal, gluten, and starch using an extruder. [Problem to be solved by the invention] Raw bait has the disadvantage of becoming a source of pollution in fishing grounds if it is minced and cast, and moist pellets are an excellent feed, but because they are granulated after mixing the raw bait and matshu. There is a problem in that the equipment such as a freezing facility and a granulator is large-scale and manufacturing is complicated. As fish feed, it is known that the addition of oil and fat is effective in increasing fish weight and improving feed efficiency, so dry pellets with a high oil and fat content are desired. In order to ensure strength or prevent oil separation, the pellets had a low oil and fat content. Therefore, it is necessary to increase the fat and oil content by some method when casting bait. In order to add additional oil and fat content, methods such as making dry pellets porous and soaking them in oil or spraying oil before casting are used, but these methods are time-consuming and There are drawbacks such as the oil turning into powder and the oil separating and floating on the water surface when bait is cast. In addition, dry pellets with a high oil and fat content that are currently being proposed for yellowtail are generally expanded and granulated using an extruder using a large amount of starch to ensure a high oil and fat content.
If the amount of fat or oil is further increased, the starch will not be sufficiently expanded and the temperature of the extruder barrel will have to be raised even higher, which may lead to the destruction of nutrients. In addition, when the oil content is increased, the oil exhibits the effect of impurities, lowering the strength, and the oil content migrates in the pellet, eventually causing oil separation on the pellet surface. [Means for Solving the Problems] The present invention has been made by focusing on such conventional problems, and relates to a method for producing dry pellets for fish farming. It was discovered that dry pellets with a high oil and fat content can be produced by this method, and the present invention was achieved. In other words, the fat content is 10-50% using a single-screw or twin-screw extruder.
(% by weight) of dry pellets for fish farming, the method is characterized in that 0.1 to 10% (by weight) of sorbitan fatty acid ester is added to oil and fat. (Requirements constituting the means) The target fish species of the dry pellets for fish farming of the present invention are saltwater fish such as yellowtail, sea bream, salmon, flounder, and striped horse mackerel, carp, trout, sweetfish, eel, yamame, tilapia, and catfish. freshwater fish or prawns,
Examples include crustaceans such as shrimp. Raw materials for pellets include fish meal, meat meal, skimmed milk powder, proteins such as krill meal and squid meal, plant materials such as oil cake, grains, starch, and gluten meal, vitamins such as vitamins B1, B2, B6, B12, and C, phosphorus, Examples include minerals such as calcium, potassium, and sodium, oils and fats such as cod liver oil, pollock cod liver oil, sardine oil, beef tallow, lard, soybean oil, cottonseed oil, and their hydrogenated oils. These raw materials can be mixed arbitrarily depending on the target fish species, body length, and season, but generally 40-50% crude protein, 10-25% starch,
Contains several percent of vitamins and minerals. The polyol of sorbitan fatty acid ester used in the present invention also includes sorbitan dehydrated products such as sorbide other than sorbitan. Examples of fatty acids include those having 8 to 22 carbon atoms, preferably those having 12 to 18 carbon atoms. These may be saturated or unsaturated. The degree of esterification of sorbitan and fatty acid may be 1 to 4, preferably 1 to 2. The sorbitan fatty acid ester is used in an amount of 0.1 to 10% (wt%) based on the fat and oil content contained in the pellets.
If the amount added is less than 0.1%, oil separation cannot be prevented or strength cannot be increased, and if it exceeds 10%, it is economically disadvantageous. Methods for adding the sorbitan fatty acid ester include methods such as mixing it with raw material powder, dissolving or dispersing it in water or oil, but are not particularly limited. The oil content in the dry pellets is preferably 10 to 50% by weight; if it is less than 10% by weight, the oil and fat components are too small to be useful, and if it exceeds 50% by weight, the oil and fat components will increase and nutrients such as protein will decrease. Therefore, it is not effective enough as feed. [Function] The dry pellets produced by the present invention have a high oil and fat content, so they have high aquaculture efficiency, hardly release oil during storage, do not have oil floating on the water surface when feeding, and form hard pellets. Because it is finished, it will not collapse. [Example] Dry pellets were produced according to the recipe shown in Tables 1 and 2 and the method below. Parts in the table are based on weight. Extruder: Alphalyzer α-70 type twin-screw extruder (manufactured by Suehiro Iron Works) Barrel temperature: 130°C Screw rotation speed: 120 rpm The raw powder was supplied to the extruder using a screw feeder. Water is supplied to the barrel by a metering pump. Liquid oil was supplied to the barrel with a metering pump. The solid fat was used by mixing it with the raw material powder.
The sorbitan fatty acid ester used in the examples was dissolved in water and supplied. Thereafter, the pellets granulated using an extruder were dried and used as test samples. Subsequently, the pellets produced above were evaluated using the following evaluation items, and the results are shown in Table 3. Granulation properties: Visual and tactile evaluation of pellets Oil separation rate: Pellets are sandwiched between two pieces of filter paper, and then 20 times the weight of the pellets (weight ratio) is placed on top of the pellets.
A load was applied. It was left at 30°C for 24 hours. The weight of the oil adsorbed on the filter paper was determined, and the amount of oil separation per 1 g of oil added during pellet production was calculated to determine the oil separation rate. Oil separation during bait casting: Pellets are thrown into artificial seawater,
Observe whether oil floats on the water surface. Strength: Using a rheometer manufactured by Fudo Kogyo Co., Ltd. and a wedge-shaped push rod as an adapter, the breaking strength was measured and defined as the strength. Table 3 shows that when the sorbitan fatty acid ester of the present invention is used, dry pellets with a low oil separation rate and sufficient strength can be obtained.

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〔Effect of the invention〕

Since the dry pellets according to the present invention have a high oil and fat content, there is no need to absorb oil and fat before casting.
There is almost no separation of oil during storage or casting, and the hard finish means less disintegration. It is also possible to slow down the sedimentation rate of dry pellets.

Claims (1)

[Claims] 1. When producing dry pellets for fish farming with an oil and fat content of 10 to 50% (wt%) using a single-screw or twin-screw extruder, sorbitan fatty acid ester is added at 0.1% to the fat and oil content. ~10% (wt%)
2. Method 2 for producing dry pellets for fish farming, characterized by adding the following: Dry pellets for fish farming produced by the production method according to claim 1.