Discussion on processing technology of producing high-grade puffed floating fish feed with low starch formula

Because of the high-grade fish, most of them are meat-eating, and there are no enzymes that decompose and use starch. The high starch content can easily cause fatty liver, which can affect growth and even death. Therefore, when designing the formula, the starch content should be reduced as much as possible; while the production of puffed floating fish feed requires a certain amount of starch and gluten to make the material puffed and floating. The higher the starch content, the easier it is to expand. Therefore, here we discuss the production conditions and production parameters of producing high-grade puffed floating aqua feed with low starch formula.

I.DOSING SYSTEM

1. Mixing evenness of feed mixer
Due to the low starch content, the batching system is required to be high to ensure uniformity of mixing; the higher the uniformity of mixing, the better the production can meet the requirements. It is recommended to be no less than 5 ‰, preferably less than 2 ‰.

2. Crushing fineness of grain hammer mill
The finer the pulverization, the easier the material expands. The more uniform the pulverization, the higher the degree of mixing; therefore, the higher the uniformity, the more uniform the production, and the better the production meets the requirements. It is recommended to pass all 40 meshes (preferably all pass 60 meshes); 80 meshes pass 98% or more.

3. Internal feed oil adding system
Because fat has a great influence on the production of extrusion floating feed pellet, and the internal addition of fat cannot be added uniformly at present. Although it can be added by atomization, it will be attached to the wall of the feed mixer and fall off causing unevenness; Adding, causing a lot of dust. It is recommended not to add fat, especially the phospholipids. The fat content of the material before expansion is preferably below 4%, and at most it cannot exceed 8%.

II.PELLETIZER CONDITIONER ADJUSTMENT

Since quenching and tempering is an important link for the production of puffed materials, quenching and tempering quality is a prerequisite for uniform puffing, so it is necessary to do a good job in the tempering system.
1. Conditioning time; ensure that the material has sufficient conditioning time to fully ripen and it is easier to produce. If there is not sufficient conditioning time, some materials will sink. It is recommended that the tempering time be above 6 minutes.
2. Conditioning temperature; only sufficient temperature can fully ripen the material, which is convenient for production operation. If the temperature is not enough, if the curing is insufficient, part of the material will sink. It is recommended that the temperature be controlled above 104 degrees.
3. Conditioning moisture; there must be enough moisture for the material to mature, but the moisture cannot be too much, otherwise it is easy to sink. It is recommended that the moisture content be controlled at around 26%.
4. Uniformity of tempering; due to the low starch content of the material, if the tempering is not uniform (uneven moisture, uneven temperature, uneven material), the produced puffed material will have a large difference, causing some submergence; It is recommended to add a quality protector.

III.FISH FEED EXTRUDER

1. Extruder screw configuration
1) The principle of inputting the highest mechanical energy is required;
2) Increase the pressurizing ring to increase the pressure of the expansion chamber.
3) Increase the resistance triangle, increase the pressure of the expansion chamber and increase the rubbing force to ensure that the materials are mature and uniform.
4) The screw opening is increased in the die section, and the rubbing force is increased to ensure that the materials are mature and uniform.

2. Increase Venturi
The opening area of Venturi is about 1.3-1.5 times the opening area of the mold.
3. Opening rate of template holes:
1) The mold aperture Φ 1.0 --- Φ 1.5 has a mold opening area of 160 --- 250 square mm / ton;
2) The mold aperture Φ 2.0 --- Φ 4.0 has a mold opening area of 130 --- 180 square mm / ton;
3) The mold aperture Φ 4.0 --- Φ 7.0 has a mold opening area of 100 --- 160 square mm / ton;
4) The mold aperture Φ 7.0 --- Φ 10.0 has a mold opening area of 90 --- 150 square mm / ton.

4. Host temperature
1) The temperature of the first section is recommended to be controlled at about 135 degrees to 139 degrees;
2) The second section temperature is recommended to be controlled at about 139 degrees to 142 degrees;
3) The temperature of the third section is recommended to be controlled at about 142 degrees to 145 degrees;
4) The fourth section temperature is recommended to be controlled at about 138 degrees to 148 degrees;

5. Pressure in the working chamber of the fish extruder
1) The pressure of the working chamber in the first section is recommended to be controlled at 20 to 30 pressures;
2) The pressure of the working chamber in the second section is recommended to be controlled at about 30 to 35 pressures;
3) The pressure of the working chamber in Section 3 is recommended to be controlled at about 35 to 40 pressures;
4) It is recommended to control the pressure of the working chamber in the fourth section at about 30 to 38 pressures;

IV POST OIL COATER

1. Due to the high-grade materials, the fat needs to be higher, and the fat should reach 12% -20%; while the ordinary external oil adding machine is more difficult to reach, it is recommended to add a vacuum sprayer.

2. If the vacuum coater cannot be installed, the external liquid sprayer must be modified, which will waste oil and produce more oil flowers on the water. The fat content can only reach 15% at most. Specific improvements:

1) Increase the oil temperature to reach 80-90 degrees, the oil temperature is high, the speed of oil entering the material is increased, thereby increasing the number of external injections.

2) Increase the material temperature (increasing the temperature of the material in the dryer) to about 80 degrees, that is, the temperature of the material when it comes out of the dryer should be increased, so that the external oil can easily enter the interior of the material, thereby increasing the amount of external oil injection (The external fuel injection can reach about 8%). But it will increase the steam consumption of the dryer (the increase of steam consumption is estimated to be about 50 kg / ton).

3) Extend the time of the material in the liquid injection machine, so that the material can fully contact and conduct with the externally sprayed oil, thereby increasing the amount of oil added to achieve the purpose. It is recommended that the oil injection time be above 6 minutes. But there will be a certain waste of fat (the amount of waste is estimated to be more than 1%-2%) and the amount of fat in the material is uneven (the unevenness may reach about 20%).

4) After the oil temperature and material temperature are increased, pay attention to adjust the cooling time and cooling air volume to ensure that the material cooling temperature meets the standard.

V.FEED PELLET DRYER SYSTEM

Due to different drying methods and different drying speeds, the shrinkage coefficient of materials will be different, so we have to adopt a drying mode with a small shrinkage coefficient. That is, high-temperature and low-air volume dryer is needed first to avoid rapid drying of the material, causing sudden shrinkage and reducing the degree of material expansion. Then slowly increase the air volume to dry to ensure that the shrinkage coefficient of the material is reduced and the floating rate is guaranteed. There is also an increase in the amount of fat. In the cooling process, the moisture taken away will be reduced, or even the moisture will not be taken away at all, just the temperature of the cooling material. Therefore, it is necessary to ensure that the moisture of the material during the drying process is about 10%. Ensure that the moisture content of the material meets the standard. details as follows:

1. For two-layer dryer

1) The first layer: the first layer of drying should be divided into four drying areas. And pay attention to the thickness of the material layer, control the thickness of the material layer at about 30 mm-50 mm. The first area: the drying temperature is controlled at about 120 degrees-130 degrees, the dehumidifying air door should be small, and the temperature of the air outlet should be high (about 100 degrees).The second area: the drying temperature is controlled at about 120 degrees-130 degrees, the dehumidifying air door is increased, and the temperature of the air outlet is higher (about 90 degrees). The third area: the drying temperature is controlled at about 110 degrees-120 degrees, the dehumidifying air door should be increased, and the temperature of the air outlet should be high (about 85 degrees).The fourth area: the drying temperature is controlled at about 100 degrees-110 degrees, the dehumidifying air door should be large, and the temperature of the air outlet should be high (about 85 degrees).

2) The second layer: the lower drying area can be divided into only two areas. And pay attention to the thickness of the material layer, control the thickness of the material layer at about 50 mm ---- 60 mm. The first area: the drying temperature is controlled at about 95 degrees-105 degrees, the dehumidifying air door should be reasonable, and the temperature of the air outlet should be high (about 85 degrees).The second area: the drying temperature is controlled at about 90 degrees-100 degrees, there is no dehumidifying wind, it is used for circulation, and the temperature of the circulating wind is higher (about 85 degrees).Note that the drying moisture should be controlled at about 9.5%-10%.

2. For four-layer dryer

1) The first layer: the upper layer drying should be divided into two (or four) drying areas. And pay attention to the thickness of the material layer, control the thickness of the material layer at about 30 mm-40 mm. The first area: the drying temperature is controlled at about 120 degrees-130 degrees, the dehumidifying air door should be small, and the temperature of the air outlet should be high (about 100 degrees).The second area: the drying temperature is controlled at about 120 degrees-130 degrees, the dehumidifying air door is increased, and the temperature of the air outlet is higher (about 95 degrees).

2) Second layer: The second layer of drying should be divided into two (or four) drying areas. And pay attention to the thickness of the material layer, control the thickness of the material layer at about 35 mm-45 mm. The first area: the drying temperature is controlled at about 115 degrees-125 degrees, the dehumidifying air door should be increased, and the temperature of the air outlet should be high (about 95 degrees).The second area: the drying temperature is controlled at about 110 degrees-120 degrees, the dehumidifying air door should be large, and the temperature of the air outlet should be high (about 90 degrees).

3) Third layer: The third layer drying should be divided into two (or four) drying areas. And pay attention to the thickness of the material layer, control the thickness of the material layer at about 40 mm-50 mm.The first area: the drying temperature is controlled at about 95 degrees to -105 degrees, the dehumidifying air door should be reasonable, and the temperature of the air outlet should be high (about 90 degrees).The second area: the drying temperature is controlled at about 95 degrees-105 degrees, there is no dehumidifying wind, it is used for circulation, and the temperature of the circulating wind is higher (about 90 degrees).

4) The fourth layer: the fourth layer of drying should be divided into two (or four) drying areas. And pay attention to the thickness of the material layer, control the thickness of the material layer at about 50 mm-about 60 mm. The first area: the drying temperature is controlled at about 95 degrees-105 degrees, the dehumidifying air door should be reasonable, and the temperature of the air outlet should be high (about 85 degrees).The second area: the drying temperature is controlled at about 90 degrees-100 degrees, there is no dehumidifying wind, it is used for circulation, and the temperature of the circulating wind is higher (about 85 degrees).Note: The drying moisture should be controlled at about 9.5% -10%.

VI.FEED PELLET COOLER

Because it is a high-grade extrusion fish feed pellet with a high fat content (12%-16%), the cooling rate of the material will be significantly slower, and the moisture taken away by cooling will also be significantly reduced. In addition, the temperature of the material is higher than that of the ordinary Therefore, it is necessary to control the cooling time (extend the cooling time) and the cooling air volume (increase the air volume), increase the uniformity of the cooler cloth, and ensure the cooling effect; ensure that the material temperature after cooling is not higher than 3 degrees at room temperature. Ensure that the material moisture after cooling should be controlled at about 8.5%-9.5%. Ensure cooling quality.

VII.FEED FORMULA DESIGN

1. Pay attention to the raw material fat, because too high fat is not good for puffing; use defatted raw materials as much as possible, preferably without adding phospholipids;

2. To increase the raw materials beneficial to puffing; for example: gluten-like substances, algae-like substances;

3. To reduce the raw materials unfavorable to puffing; for example: molasses, Chinese herbal medicines, raw materials with high sugar content, as little as possible.