Aqua Feed International, VIV and Dr. Mian N. Riaz from Texas A&M University hosted their annual 7th Aqua feed conference at the VIV Event in Bangkok, Thailand on March 7th, 2023. This conference was attended by more than 60 participants from all over the world. Below are the highlights for each talk given by ten international speakers at this conference.
How to Select an Extruder for Making Aqua Feed
Dr. Mian N. Riaz, Head of the Extrusion Technology Program at Texas A&M University, USA explained that in today’s market, several companies offer all kinds of extruders for making aqua feed, which can make the process of selecting an appropriate extruder very confusing for the consumer. There are too many choices in the market for buying an extruder. For examples, Single screw extruder; twin screw extruder; wet extruder; dry extruder; interrupted flight extruders; segmented types extruder; non-segmented extruder; high sheer extruder; low or medium shear extruder; extruder with vented barrel; conical screw extruder; thermal extruder; intermeshed co-rotating or counter rotating twin screw extruder; extruder with constant speed motor drive vs variable speed drive; extruder with back pressure valve; extruder with external density control system; extruder with manual, semiautomatic and fully automated control system; extruder with capabilities for online analysis; extruder with volumetric or gravimetric feeding system; extruder with different compression ratio; expanders without preconditioner and with preconditioner. Additionally, there are even several options available for preconditioner, for example, single shaft preconditioner; double shaft preconditioner; differential diameter preconditioner (DDC); two stage preconditioners; high intensity preconditioner (HIP) and high shear conditioner (HSC), etc. Deciding on an appropriate selection depends on what kind of aqua feed needs to be made. Questions such as is it floating, sinking, slow sinking, high fat or low fat, semi moist or dry, the size of the pellet need to be considered first. An extruder can make feed from 0.6 mm to 60 mm; thus, selection of an extruder will depend upon the size of the pellet. All these factors will dictate what type of extruder you should select for making aqua feed.
Why Particle Size Matters in Aquaculture Feeds
Phil Erickson from Reynolds Engineering and Equipment, USA, explained that the first step in making aqua feed is to prepare your raw material using proper grinder and pulverizer for extrusion and that can be very costly, if not careful, you can spend lot of energy and efforts and then still ended up with poor quality pellets. Size reduction requirements for most feed and food industries vary upon application, which in aqua feed is between macro and micro particles. The size of particles bound together in a pellet, whether pelleted or extruded, influence feed production in the plant and performance in an aqua enclosure. This talk was focused on size reduction equipment currently used in agriculture and aquaculture applications and physical properties of particles, focusing on current and upcoming issues associated with size reduction in aquaculture.
Advanced Techniques for Extruded Shrimp Feed
Michel Bauer Pereira, Global Application Manager – Aqua and Pet; Andritz, Denmark gave an overview about making shrimp feed with extrusion technology. There are several different types of shrimp feed that is being made such as larvae and post larvae, starter, grower, finisher and brood stock. This feed can be herbivore and omnivore and pellet stability in water and making it 100 percent sinking are most important factors for shrimp feed. Finished feed must have high protein, low starch and fiber and the required amount of minerals and vitamins. To make good quality shrimp feed grinding is most important, then conditioning of the raw material and extrusion processing. He discussed the expansion control system which can be used to make 100 percent sinking feed and this system can be adopted with extruder after the die. After extrusion drying of these small pellets is a challenge and then coating these pellets with oil and digest for palatability is also an art because of the small diameter.
Selecting the Right Dryer for Fish and Shrimp Feed
Albert Wang – from CPM Asia provided an overview of drying theory, dryer in feed industry, what are the factor which effect dryer effectiveness can one dry fit all the industry and most importantly energy and cost of drying. He explained different types of dryer for the aqua feed industry, including horizontal dryer, vertical box type counterflow dryer, and carousel dryer with vertical cross counter rotatory flow. He also provided dryer comparison for all these dryers for the moisture uniformity, retention time, energy demand, product change over, area requirement, cleaning in place and steam consumption. He explained that not one dryer fits all needs, some of them can over dry and some of them can under dry the fish and shrimp feed. All these variations translate into energy loss. He concluded his talk, that not one dyer fits all. Moisture uniformity is the key point to effective drying process and uniform moisture dryer can increase profit.
Premium Extruded Shrimp Feeds
Dana Nelson Extru-Tech, USA gave his talk on premium extruded shrimp feed. He started his talk by explaining what extrusion is and its benefits. Cooking extrusion offers many advantages over alternative forming technology and as a result has been the preferred method for producing many aquatic feeds. Critical attributes for shrimp feed are that it must sink and stay stable in water for some time. He explained that shrimp feed production has not been standardised globally. Finding the ideal method for producing shrimp feeds is not a new debate and worldwide there is no consensus about the “best” method. He provided several different options to process shrimp feed. One of those options is to control expansion with the new concept of advanced Densification Technology (ADT) refinements which make it quite different. The basic concept is to move the cooking process away from the forming process (the die) in new ways. ADT components can create HIGHER heat and shear in the initial stage of the extruder than is typical (online control). The goal is to get sufficient heat early in the process allowing the final stages to focus on densifying and forming pellets. ADT equipped systems offer screw geometry, and conditioning dwell times that are atypical. The key components are: Mid Barrel Valve (MBV); Non-Conical final screw and head; Novel die and tube adapters; New die and cutting systems focused on increasing surface area for holes and longer knife options; Innovative configurations and screw segments. In summary, new die designs have eliminated the bottleneck small pellet sizes have been plagued with. This has always been a factor in low-fat shrimp formulations and feeds smaller than 3.0mm. Surface area is increased dramatically to permit more open area and hole geometry can be designed for densifying the pellet and facilitating higher capacity rather than restricting flow and ensuring sufficient cook.
Making Floating and Sinking Feed Using Twin Screw Technology
Hadrien Delemazure, Manager for Pet Food and Fish Feed Processing, Clextral France explained that twin-screw extrusion has been extensively used to manufacture quality aqua pellets for the last 40 years. Recipes are getting more complex and diversified, fishmeal and fish oil are being replaced by alternative raw materials, which sources may vary according to international prices fluctuation and availability. Furthermore, in order to produce both optimal floating and sinking feed, precise control of the pellet expansion and density is necessary. Mr. Delemazure discussed the twin screw extrusion technology making the floating and sinking feed. Aquafeed production lines are today expected to offer more process flexibility, reliability and durability that can be achieved using twin-screw extrusion technology. Currently we have choices to use single or twin-screw extruder to make aquafeed, and twin-screw extrusion provide more flexibility and choice to make different sizes of pellet and it allows to make floating or sinking feed as well. Twin-screw extrusion has been extensively used to manufacture quality aqua pellets for the last 40 years. While recipes are getting increasingly more complex and diversified, fish meal and fish oil are being replaced by cheaper alternative raw materials, which sources may vary according to international prices fluctuation. Furthermore, in order to produce both optimal floating and sinking feed, precise control of the pellet expansion and density is necessary. Aquafeed production lines are today expected to offer ever more process flexibility, reliability and durability that can be preferably achieved through twin-screw extrusion technology.
Aquafeed Production, Focusing on Precision
Dr. Michael Cheng, Global Business Development Manager, Pet and Aqua; Buhler, Switzerland disused Aqua feed extrusion; Focusing on precision. By explaining how the precision has move in extrusion technology from automated plant to digital assisted plants to self-adjusted plants to finally smart plants. These smart plants provide solutions to digital related services, and expert services. These plants are targeted to provide highest yield, optimize manpower, support operator, efficient energy uses, flatten consumption, optimise product flow, real time monitoring, enhanced quality, digital assistance for process tracing, higher capacity, optimal performance and reduce downtime. He explained how sensor technology can be used in granulation control loop for precision particle size distribution to make sure it is not too fine or too coarse. This can provide several benefits such as uniform granulation for downstream process, mixing, pre-conditioning, extrusion; real time data of production; narrowing start-up deviations with new products; adapting to raw material fluctuations; compensating wear of the hammers; compensating wear of screens and detection of broken screens. In extrusion precision can help in efficient eco control, flexible specific mechanic energy, operator friendly, bulk density control, quality control and preconditioner control. Precision control for moisture and thermal energy management in preconditioning. In extruder precision can help in product flow capacity which in result will be higher throughput, stable running, and consistent product quality. He also discussed real time bulk density control precision system, which can help control the density automatically by adjusting the SME and thermal / pressure adjustment in extruder barrel.
Intelligent Application in Aquafeed Processing
Garrick Yan – Famsun Group focused his talk on new technologies to improve efficiency. He discussed startup waste control technology, extruded with better uniformity, and kept improving OEE/YE with data utilisation. He explained how a feed mill can reduce their start up waste with new type of preconditioners with water & steam injected separately in each layer. Optimised paddle configuration: automatic check the steam quality and adjust the parameters; applying thermal model to improve the temperature increasing speed. He also discussed different ways to improve the pellet quality such as density control system (P-DCS). In this system, the Pressure system enables the use of high energy input levels to cook the starch. After the pellet leaves the die, the high-pressure environment elevates the boiling point, which prevents the water converting from liquid to vapor, hindering expansion. It does not require a special screw configuration to produce both floating and sinking feed. The pressure level can be adjusted to manipulate the density. He explained how to improve water stability by better starch gelatinisation. Higher Temperature and more retention time leads to higher SG. Higher screw speed result in more gelatinized starch. High melt moisture has a cooling effect, leading to a reduction in melt viscosity and an increase in the total mass flow rate that negatively impact SG. He discussed some tips for producing micro shrimp feed. Extruded micro pellets can replace traditional crumble feed, enabling feed manufacturers to produce more nutritious high value.
Aqua Feed Coating System
Caleb D. Townsend- APEC -USA gave an overview of different coating systems. He explained all different types of coating system which are available for the aqua feed industries, discussed pros and cons for each system and then elaborated automated spinning disk coating system. Some of the advantages of spinning disk system is we can apply single or multiple liquids through one inlet, and it is totally closed system – no airborne mist. Overspray falls into mixing conveyor for further blending. Utilizing high speed rotating liquid disks for atomization and no spray nozzles – With this we can apply slurries and powders. There is no low-end limitation on liquid addition. Spinning disk provides greater product exposed surface area – a 13” diameter dry disk has a 40-7/8” long curtain exposed to the liquid spray. A twin-screw mixing conveyor has gentle but active mixing – ribbon flighting with kick back paddles and it is 10 ft. conveyor = approx. 60 seconds of retention and mixing with C.V.’s of low teens to single digits. The goal is to coat the pellet uniformly and maintain the quality of coating. A typical coating system will have pumps and meter, control system and some types of scale to measure the flow of the material.
Soy Products for Aqua Feed in Thailand
Chuchai Kanjanamayoon from USSEC Thailand Technical Manager Aquaculture, explained nutritional value of soybean and its ingredients. He explained different methods to process soybeans and it different ingredients. He discussed advantages and disadvantages of soybean meals; soy concentrates and soy isolates. He elaborated on the new soy product which is getting lot of attention because of its better nutritional quality “fermented soybean. These are produced from SBM which is inoculated with fungi, bacteria, yeast or a combination of these microorganisms. Genera Aspergillus and Lactobacillus solid-state fermentation (SSF) or submerged fermentation. SBM is usually incubated at a moisture content of 45 to 50%. The wet substrate is inoculated with microorganisms and the fermentation process. Different microorganisms secrete different enzymes and in varying quantities. Improved nutritive value and reduced levels of antinutritional factors. FSBM has crude protein and amino acid contents about 5-10 percent higher than SBM. FSBM inactivation of the allergenic proteins glycinin and -conglycinin and can potentially decrease the trypsin inhibitor, phytic acid, and saponin contents of SBM. He also explained the US soy Sustainability assurance protocol. A set of guidelines and standards developed by the United Soybean Board to promote sustainable soybean production in the United States. The principle behind the SSAP is to provide a framework for soybean farmers to adopt sustainable practices that protect the environment, promote social responsibility, and ensure economic viability.
Article contributed by Dr. Mian Riaz, Texas A&M University, USA
