Determination of the most effective land based processing methods with regards to products, markets, scalability and economics. D3.5

Sammendrag

Mesopelagic biomass has been further investigated with regards to applications towards food and feed. Impacts on fish composition, processing yield and quality of mesopelagic fish and selected products (Fm, Fm oil, FPC, FPC oil) has been investigated in laboratory scale storage trials (TRL 4) and demonstrated in pilot scale processing trials (TRL 5). The laboratory trials were used to study the degradation processes in mesopelagic fish under variable storage conditions (time, temperature). The pilot scale demonstration study was used to identify the most promising processing conditions for mesopelagic fish and to reveal potential limitations for efficient total utilization and bioeconomic processing of the mesopelagic biomass. In pilot scale trials, prototype Fm and FPC products were produced for further biological evaluation in collaboration with stakeholders. The main challenges related to processing of mesopelagic fish have been identified, and practical and economic considerations for successful total utilization of mesopelagic biomass has been evaluated. Alternative methods for production of food and nutraceuticals have not been further explored due to the lack of available mesopelagic fish. The lab-scale processing uncovered challenges related to fat separation, and this was confirmed in the pilot scale trials and resulted in a high fat level (26.5%) in the Fm. The TVN level in mesopelagic fish was very low (9-11 mg N 100g-1 ), confirming a near to optimum freshness level, known by the industry to cause separation challenges with resulting high fat level in the fishmeal. The laboratory studies confirmed that the fat separation improved significantly after some storage time in a temperature related way. Storage of the pelagic fish will cause a partial autolysis and a balance between microbial degradation (i.e., increased TVN level) and improved fat separation need to be further studied. No major challenges are identified preventing upscaling to TRL 9 of the Fm and fish silage technology reported in this study. Existing Fm processing plants have considerable unused capacity and based on observed yields the processing costs of mesopelagic fish will be comparable to other raw materials. The main hurdles for development of an industrial viable utilization of mesopelagic fish are related to harvesting efficiency and fuel costs. Conservation technology identified in this study based on cooling to 0 °C or below will make it possible to extend the trawling period to 10 days or more. The laboratory trials and pilot-scale productions showed promising results in the production of mesopelagic Fm and FPC. The quality of fresh frozen fish was high at the start of storage, and the stability strongly dependent on temperature in the unpreserved fish. Acid preservation of mesopelagic fish efficiently inhibited bacterial growth, and TVN showed a temperature dependency that suggest that mesopelagic fish is best preserved at 10°C. The conventional methods used for producing Fm and FPC were effective with respect to quality and yields, while problems related to oil separation were observed irrespective of process and production scale. The results provide valuable insights into the most optimal processing methods and potential for industrial use of low trophic mesopelagic fish species.