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Possibility of Rendering Koi Carp

Koi carp, one of the most invasive fresh water fish, is a pest in New Zealand waterways. Pest management plays a vital role in protecting the natural environment and efforts are being made to eradicate koi carp. The aim of this study was to identify possible uses for koi carp that will help offset eradiation costs. An extensive literature search to identify feasible products that could be made from koi carp showed that producing fish meal and fish oil had potential. The commercial processes are well established and these processes were relatively simple and economic. The high protein meal and fish oil produced could be used as ingredient in formulated animal, pet and fish feeds. It is proposed that whole fish are processed, eliminating the need to clean, gut and fillet the fish. A series of experiments were done out in the laboratory to simulate the two common commercial rendering systems – wet rendering and dry rendering. Minced whole koi carp caught in Lake Waikere were heat treated for various temperatures and processing times to cook the protein. The resultant meal was then dried. High temperature processing under pressure and solvent extraction (to remove the maximum amount of oil) were also simulated. A dried meal could be obtained by continuously heating and stirring minced fish for 3 h to an endpoint temperature of 132°C. Free oil could be obtained by pressing or centrifuging the dried material. The final meal yield was 25-27% of the original wet fish weight. It had a composition of approximately 25% protein, 8-9% lipid and 2.2% minerals, based on a meal moisture content of 6% . The oil yield was only 1.5% (wet rendering) and 5.2% (dry rendering) of the original fish weight, indicating that koi carp are not a suitable source for oil. Pressure processing produced similar yields as wet rendering process. It is recommended that further work is done to determine the effect of seasonal variations in koi carp on meal yields and composition. Research should also be done to determine whether the acceptability of the meal in formulated animal of fish feeds. Lastly, an economic analysis on processing koi carp collected from eradication programmes should be done.
Type of thesis
Viswam, J. (2010). Possibility of Rendering Koi Carp (Thesis, Master of Engineering (ME)). University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/5007
University of Waikato
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