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Difference Between Feed Extruder And Feed Pellet Machine

Date: 07/15/2020 08:41:31 From: feed-pellet-plant.com Clicks:

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Both fish feed extruder and feed pellet machine can make feed pellets for animals, but the price of feed extruder is higher than feed pelletizer, so the extruder is generally used for pet pellets and aquatic pellets. Feed pellet machine is generally used for poultry, ruminants and livestock feed pellets. The feed pellet machine can also be used for aquatic feed, but it is a pellet machine with a three-layer modulator. If it is a large-scale aquatic feed pellet production line, the extruder can not meet, you can consider using a three-layer modulator feed pellet machine.

Difference Between Feed Extruder And Feed Pellet Machine
Difference Between Feed Extruder And Feed Pellet Machine

I.Extrusion VS Pelleting

1.Extrusion

Extrusion is a high temperature short time (HTST) heating process, it minimizes the degradation of food nutrients while improving the digestibility of protein and starches. Fish feed extruder is an ideal machine that designed for processing floating or sinking aquaticfeed just by adjusting the formula. Extrusion requires higher levels of moisture, heat, and pressure than pelleting. Temperature higher than 100℃ is needed in order to achieve expansion of the feed as it leaves the die. Extrusion consists of wet extrusion and dry extrusion.

Feed Extruder
Feed Extruder

Dry Extrusion and Wet Extrusion

Different shapes and sizes of aquatic feed can be produced by extrusion technology. Extrusion with steam preconditioning is known as wet extrusion and extrusion without steam preconditioning is called dry extrusion.

Preconditioning is a very important part of the wet extrusion process for steam or water injection into either the conditioner and or the extruder barrel. The heart of the extruder machine working is: preconditioning, cooking and die shaping. High temperature and high pressure process can kill the salmonellosis and bacterial infections and also makes the pellets easily to digest. Wet extruder is usually employed for high quality pellet production in large scale!

Without utilizing preconditioning, dry extrusion employs lower moisture levels. Therefore it is suitable for processing low moisture and high fat feed material in small and medium sized production.

Dry type extruder or wet type extruder are often equipped with one screw or twin-screw. Twin-screw is two screws of equal length placed inside the same barrel. Extruder with twin screw develops on the basis of single screw extrusion machine, which is more complicated than single screw extruder. Moreover, the price and maintenance of twin screw extruders are higher than single screw ones.

2.Pelleting

Pelleting is the process to compress small particles into larger solid with a given shape and texture, which involves the combination of moisture, heat and pressure. These larger homogenous particles agglomerating from small ingredients are also called dense pellets that sink rapidly in water. The ring die aquatic feed pellet mill is the professional pelleting machine for pelleted aquafeed making.

The main factors affecting pelleting are ingredients characteristics, moisturizing or steaming before pelleting, die thickness and binders ect.

From the above, we can see that extrusion is characterized by higher levels of moisture, heat, and pressure than pelleting. Usually, the mixture of finely ground ingredients is conditioned with steam or water and may be precooked before entering the extruder. Therefore extruded feeds are more firmly bound due to the almost complete gelatinization of the starch and result in less fines than pellets.

feed pellet machine
feed pellet machine

II.Commonness and difference between feed extruder and feed pellet machine

Similarity of a pellet mill and the extruder

1.Both utilize steam, pressure and temperature.

2.Both have dies to form the pellets however, they work on different principles:

The differences are the following:

1.A pellet mill shapes the pellets by compression through long land dies thus the pellet is dense. In most cases, a pellet binder is need in the formula to facilitate the cohesion of the pellet.

2.An extruder will expand the pellet through substantial gelatinization of the starch, expansion and increased porosity thus the reduction of the density. No need for the addition of a pellet binder in most cases.

3.In the case of floating fish feed, extrusion allows you to control the buoyancy of the pellet by the degree of starch gelatinization dictated by many factors such as the moisture content, extrusion temperature, and amount of shear generated and the size of the die used.

4.In pet food, palatability and lower microbial load are crucial and extrusion enhances both.

5.Extrusion allows you to use higher level of oil or fat without creating much fines thus higher integrity of the pellet.

III.Extruded feed VS Pelleted feed

Performance Extruded feed Pelleted feed
Bonding degree Strong Strong
Floating and sinking Beneficial Just sinking
Stability in water Better Good
Fines in aquafeeds fewer Few
Nutriment digestibility Higher Lower
Funding Bigger Smaller
Processing cost Higher Lower
Equipment wear Slower Quicker

As can be seen from the table above, the stability of the pelleted feed is not as high as the extruder, and it is easy to lose nutrients after a long floating time. Aquatic feed produced from extruded feed is better.There are three types of pellets produced by extrusion: fast-sinking, slow sinking and floating form that is available in all water

Related Article

Structural characteristics, classification and working principle of feed extruder

The market competitiveness of feed extruder

I Need An Extruder To Produce Fish Pellets

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