There are significant financial and environmental benefits to utilizing fish meat or protein lost in catfish processing. The value can amount to hundreds of millions of ISK based on that 60 thousand tons annual production of fresh and frozen catfish products. According to a study by Matís (Matvælarannsóknir Íslands), Brims and Toppfisk, less organic matter is released into the environment by utilizing fish meat or protein in the processing.
The study, entitled "Unused protein in wastewater from fish processing", describes an assessment of water consumption and protein loss during filleting and skinning in catfish processing. It states that if it is assumed that about 1% of raw material weight is lost during filleting and skinning, this corresponds to about 1,200 tonnes of fillet products compared to 60 thous. tonnes of annual production of fresh and frozen catfish products. The value can therefore amount to 120-500 million ISK per year, depending on whether the fish mass is priced as marlin or more valuable products for human consumption. It should be noted that various factors can affect the loss of fish meat during processing, such as the condition of raw materials and processing equipment, but its variability was not assessed.
The study found that the water consumption was about 0.5 l / kg of product during filleting and comparable water consumption during skinning when based on the processing of 2 kg of fish and 50% processing efficiency. The water was filtered with several sieves of different roughness (0.25-1mm). With coarse filtration (1mm) most of the blood vessels could be separated and straightened, but the finer the filtration, the whiter and more homogeneous the fish mass became. By isolating dry matter from wastewater, it is possible to increase the value and improve the utilization of seafood, while at the same time promoting more environmentally friendly production methods. Of course, some effort has to be put into isolating the proteins, but with relatively simple filtration equipment, a significant amount of the proteins that are now destroyed in the effluent of fish processing plants could be achieved.
The project was carried out by experts from the Fisheries Research Institute (now Matís ohf) in collaboration with Brim and Toppfisk funded by AVS Fund.