1st Nordic Drying Conference - NDC'01, Trondheim, Norway, June 27-29, 2001

LOW TEMPERATURE HEAT PUMP DRYING TECHNLOGIES FOR ENRICHED LIVE FEED FOR USE IN MARINE FISH LARVAL DIETS Odilio Alves-Filho1, Jose Rainuzzo2 1 Center for Dewatering R&D at NTNU-SINTEF SINTEF Energy Research, Trondheim, Norway E-mail: odilio.alves@energy.sintef.no 2 SINTEF Fisheries and Aquaculture AS Trondheim, Norway Keywords: DHA, EPA, lipid, powder, property, protein, PUFA, rotifer. ABSTRACT The rearing of larval stages of marine fish is mainly based on the use of live feed organisms such as rotifers and Artemia. The enriched live feed (rotifer, Brachionus plicatilis) can be used as partial or full diet for larval stages marine fish species. In many cases the live feed production may involve high production costs, large space utilization and it may have limited availability. On the other hand artificial diets offer a number of advantages such as composition, size and availability. However, the current industrial technologies are not appropriate for the production of artificial diets for feeding early larval stages of marine fish. The Center for Dewatering R&D at NTNU-SINTEF has built and tested several heat pump dryers, which can be applied in drying of heat sensitive materials. Presently, we call them shortly as EcoEffDryers since this heat pump drying technology is environmentally clean and the dryers can save up to 80% of the electrical energy consumed by conventional process. The adiabatic heat pump dryer (AHPD) is suitable for processing sticky materials containing sensitive compounds such as lipids, protein and enzymes. This paper describes the drying tests of rotifer using the low temperature heat pump dryer as well as the appropriate conditions for freezing and granulation. The analysis of the results showed that the heat pump dryer is able to produce rotifer powder with high quality and it allows the control of both the powder particle size and bulk density. Moreover, there was no protein loss and the powder had higher enzymatic activity than vacuum freeze dried sample. Future drying tests of rotifers and similar live feed materials will be performed using a new carbon dioxide heat pump dryer that was recently built at The Center for Dewatering R&D. This dryer incorporates advanced technology and instrumentation for regulation and control for improved product quality, higher COP and SMER.

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