Use of round goby (Neogobius melanostomus) processing waste in bioeconomy

Round goby (Neogobius melanostomus) in Baltic Sea is an invasive species, which over the past decade spreads rapidly. Round goby was indirectly introduced from Black or Caspian Sea. During these years catch reaches several thousand tons. Fishermans acquire these fish sourcing but appears problems with implementation. The development plan of Latvia establish to use these species of fish for human consumption and that is why in research have been considered possibility of fish processing residue (internal organs, head, bones etc.). In accordance to bioeconomic principles, processing waste is considered to be raw material for the production of high added value products. Evaluating the use of round goby processing waste from the economic and technical viewpoint in the context of Latvia we examine the extraction of fish oil. During the research fish's total amount lipids has been determined while using Bligh/Dyer method. The oil has several quality indicators - amount of free fatty acids, acid value and saponification value. Content of protein, moisture, ashes and carbohydrates in the fish has been determined. Round goby's head consists of 81.18 ± 1.10 % water, 4.24 ± 0.10 % ash 1.00 ± 0.13 % fat, 16.60 ± 0.40 % protein, 0.0 ± 1.00 % carbohydrates. The body consists of 83.68 ± 12.86 % water, 3.75 ± 0.01 % ash, 0.67 ± 0.07 % fat, 16.60 ± 0.40 % protein, and 0 ± 1.00 % carbohydrates. While assessing production capabilities, attempts were made to obtain oil through heat extraction and microwave extraction methods. After numerous applications of centrifugation using the heat extraction method fish gelatin was acquired, there were no findings of oil in the upper part of the liquid layer. Similar results were obtained using the microwave extraction.