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November | December 2010 Feature title: Pelleting and extrusion in aquafeed technology

Deadline: 30/04/2013

For advertising opportunities please contact the Marketing Team | Tel: +44 1242 267706

FEATURE

Pelleting and extrusion in aquafeed technology

by Kevin, Allance Machinery,

A

quaculture is a developing activity around the world. As the industry grows, so does the aquafeed market. Aquafeeds are comprised of a number of ingredients that are mixed in various proportions to complement one another to form a nutritionally complete compound diet. According to the physical characteristics, they can be divided into powder, particle, pelleted and extrusion aquafeed. They can also be divided into sinking, slow sinking and floating aquafeed according to their buoyancy. On the basis of aquafeed energy, they can be divided into low energy, medium energy and high-energy aquafeeds.

Raw materials for aquafeed production

transformed by fish. Raw materials for aquafeeds include cereals (maize, wheat, barley, rice, oat etc.), cereal by-products (wheat flour, corn bran, wheat bran etc.), meat meal, fishmeal, shrimp meal, squid meal, blood meal, poultry by-product meal, (full fat) soybean meal, other vegetable protein meals, fats and oils, vitamin and mineral premix, salt, stabilizers and binders etc.

The major components of aquafeeds are protein (plant protein, animal protein and single cell protein), starch (sinking aquafeed consists more than 10% and floating aquafeed consists more than 20%), crude fat, raw fibre, crude ash and micronutrients. Starch has great gelatinization under high temperature and high humidity conditions. It can improve the stability of aquafeeds and extrusion density of extruded aquafeeds.

Hardness, size, buoyancy, durability and water stability must all be taken into account. Aquafeed processing technology is not unique. It relies on the development made in conventional animal feed processing technology, but with some specific applications. The main processing technology for aquafeeds is pelleting (mainly produce sinking aquafeeds) and extrusion (can produce sinking or floating extruded aquafeeds).

Aquafeed pelleting technology is stricter than common animal pelleted feed. Typically, sinking aquafeeds are mostly made with feed pellet mills. Pelleting is still the predominate method for sinking feed production. The aquafeed pelleting processes is described below:

Grinding It is a particle size reduction process for raw Common basic raw materials to the Aquafeed processing technology manufacture of most aquafeeds are similar to The manufacture of aquafeeds is more materials by hammer mills. Grinding is benefithose employed in the manufacture of other complex than common feed manufacture. cial for the mixing operation and can improve the nutritional utilization types of animal of raw materials. For feeds. However, it Table 1: Classification of aquafeeds based upon the energy levels and processing technology aquafeed processing, an should be noted Low energy Medium energy High energy ultra fine feed hammer that aquafeeds mill is necessary. should avoid the use of high levels Protein (%) 30-40 43-52 40-48 Mixing of plant or vegThe ground materials etable fibres and Fat (%) 6-13 12-25 22-35 must be mixed with carbohydrates Processing machine aquafeed pellet mill extruder/aquafeed pellet mill extruder the proportioned raw which are poorly Target species salmon, trout seabass, turbot carp, tilapia materials to obtain a digested and 40 | International AquaFeed | March-April 2013

FEATURE Table 2: Starch contents of common energy feed raw materials Raw material

Starch content (dry matter)

Raw material

Starch content (dry matter)

Whole maize Flour

70-75%

Sorghum

71.6%

75-80%

Whole rice

81%

Wheat bran

5-8%

Whole barley

60%

Winter wheat

65.5-82%

Whole oat

45%

21.5%

Soybean meal (44%)

0.5%

Wheat middling

homogeneous mixture. During the mixing process, feed ribbon blender or double paddle feed mixer is the most commonly used equipment.

Pelleting Pelleting can be defined as the agglomeration of small particles into a larger solid with a given shape and texture, by means of a mechanical process in combination with moisture, heat and pressure. The main factors which affect pelleting are ingredients characteristics, moisturizing or steaming before pelleting, die thickness and binders etc. The ring die aquatic feed pellet mill is the professional pelleting machine for aquafeed processing.

Cooling The temperature of the aquafeed pellets squeezed out the pellet mill is high. They

should be cooled before other operations. A counterflow pellet cooler is a high-efficiency cooling machine.

Coating Coating can improve upgrade the aquafeed quality. The physical property of the feed is improved. The fat sprayed on the aquafeed pellets has certain permeability; it can permeate into the pellets in subsequent crafts and transport process. That can reduce the scatter of feed particles and dust. The fat spraying machine is also known as feed pellet coating machine.

Crumbling It is a necessary process in aquafeed pellet processing as some fish need smaller pellets.

The roll type crumbler can break the aquafeed pellets into smaller particles.

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Screening In order to improve aquafeed quality, fines from cooled aquafeed pellets should be removed and the pellet size should be uniform. Rotary feed pellet grading sieve is just the machine.

Aquafeed extrusion technology A significant application of the extrusion process is in the production of aquafeeds.

Extrusion has won some popularity and is widely accepted. Compared to the pelleting method, extrusion can be defined as a technological process, namely, forcing feed raw material in one or more of the following process conditions (such as mixing, heating, cutting etc.) flow through the die, make material forming or eruption gasification. Extrusion allows buoyancy control to make floating, sinking or slow sinking feed by changing the

ADVERTISE WITHIN THIS FEATURE

•

You can advertise within this space for UK£920 or see the back page of this document for other prices & sizes

•

You can advertise within this space for UK£920 or see the back page of this document for other prices & sizes

•

The advert size can be changed to suit your existing artwork

•

The advert size can be changed to suit your existing artwork

•

Booking deadline is 30/04/2013

•

Booking deadline is 30/04/2013

We guarantee - That your advertisement will be put in front of more of your target market than that achieved by any one of our competitors

We guarantee - That your advertisement will be put in front of more of your target market than that achieved by any one of our competitors

Contact the Marketing team on - Tel: +44 1242 267706

Contact the Marketing team on - Tel: +44 1242 267706

Lee Bastin - leeb@aquafeed.co.uk

Lee Bastin - leeb@aquafeed.co.uk

Darren Parris - darrenp@aquafeed.co.uk

Darren Parris - darrenp@aquafeed.co.uk

Tom Blacker - tomb@aquafeed.co.uk

Tom Blacker - tomb@aquafeed.co.uk

March-April 2013 | International AquaFeed | 41

FEATURE

extrusion condition including temperature, pressure, die aperture diameter and shear rate etc.

Dry or wet extrusion Different shapes and sizes of aquatic feed can be produced using extrusion technology. Extrusion with steam preconditioning is known as wet extrusion and extrusion without steam preconditioning is called dry extrusion. Dry extruders were used in processing low moisture, highly expanded starch products and in processing whole soybeans to full-fat

soy flour for both the food and feed industries.

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 most important aspect of the preconditioning system is the potential for additional mixing and the retention time, which is necessary for chemical or physical reactions to take place. The Allance aquafeed extruder for example, can produce dry and wet aquafeeds.

Dry feed pellets are stable for relatively long periods, for convenient storage and distribu42 | International AquaFeed | March-April 2013

tion. The wet type processing needs a boiler to make steam to the conditioner and ripen the raw material in advance.

Twin-screw extrusion is ideal for aquafeed According to the operation methods, extrusion equipment generally falls into two categories: single-screw extruders and twin-screw extruders. Producing small pellet aquafeed by single-screw extruders directly has many advantages, such as low ingredient cost, less fine generated, good water stability and pleasant appearance. Twin-screw extruders (TSE)

FEATURE Table 3: Extruded aquafeeds versus pelleted aquafeeds Extruded feed Bonding degree

strong

strong

beneficial

just sinking

Stability in water

better

good

Fines in aquafeeds

fewer

few

Floating and sinking

were first used in the 1950s for manufacturing thermoplastics.

They were developed on the basis of singlescrew extrusion machine, with a double screw installed side by side in the barrel. A fully meshed co-rotating (both screws turn same direction) extruder greatly improved material conveying, pumping and mixing characteristics.

Compared to a single-screw extruder, a TSE has a much wider operating range in terms of use of moisture, internal fat, mechanical energy input and product size.

The domestic high quality twin-screw extruder has reached an advanced level in technical performance and manufacturing level

Pelleted feed

Nutriment digestibility

higher

lower

Funding

bigger

smaller

Processing cost

higher

lower

Equipment wear

slower

quicker

with high property price ratio and is the best choice of the aquatic feed processing industry.

The main advantages of twin extruder described as follows: •Twin-screw process mandatory delivery and self-cleaning feature, making the material stay in the barrel for a short time and uniformity.

•As two screws knead and rub each other, extruder enables material mixed and ripened more fully in lower energy consumption. The whole ripening degree can reach more than 95 percent, water stability last for 24 hours.

•The biggest characteristics is that it can mix all kinds of raw materials regardless

of its formation. This will also enable fish farmers use a wider range of ingredients.

Conclusion The production of aquafeed is the fastest growing sector in the global feed industry.

Although a large amount of aquatic feed is still produced by conventional pelleting technology, extrusion is being utilized to a larger extent because it has several advantages over pelleting.

So, pelleting or extrusion? It’s according to various factors that discussed above.

More Information: Website: www.pellet-machine.net

ADVERTISE WITHIN THIS FEATURE •

You can advertise within this space for UK£1,678 or see the back page of this document for other prices & sizes

•

The advert size can be changed to suit your existing artwork

•

Booking deadline is 30/04/2013

We guarantee - That your advertisement will be put in front of more of your target market than that achieved by any one of our competitors Contact the Marketing team on - Tel: +44 1242 267706 Lee Bastin - leeb@aquafeed.co.uk Darren Parris - darrenp@aquafeed.co.uk Tom Blacker - tomb@aquafeed.co.uk

March-April 2013 | International AquaFeed | 43

March-April 2013 - Advertising promotion: Display advertising: Advert size

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Advertise within this issue and your advert will appear in: Our printed magazine Our online edition magazine Two issues of the E-Newsletter *The Features Archive of www.docstoc.com, www.scribd.com & www.slideshare.net

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Please note that invoices are raised in UK£’s and so exchange rates may vary slightly Contact the Marketing team on - Tel: +44 1242 267706 Lee Bastin - Email: leeb@aquafeed.co.uk Darren Parris - Email: darrenp@aquafeed.co.uk Tom Blacker - tomb@aquafeed.co.uk

Deadline: 30/04/2013 We guarantee • To expose your advertisement to more people, more often and for much longer than anyone else • That your advertisement will be found and redistributed by more of the right people • That your advertisement will be put in front of more of your target market than that achieved by any one of our competitors • To deliver the industry’s maximum ROI (return on investment) based on your advertising spend with us

Digital Circulation As well as appearing in the paper version of the magazine, this feature and the advertisements placed within it will be included in a digital re-print and circulated electronically with fully functioning links. The full magazine will also appear as a digital version on our website and in the magazine’s online archive.

Article Reprints We can produce either four or eight page versions of any specific feature that has appeared in the magazine (including back issues up to 2006). These features have been used by our customers as point of sale materials, promotional materials for shows and exhibitions etc.

For full details please visit www.aquafeed.co.uk/reprints