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To revalue the by-products of fishing and promote their great nutritional interest.

The development of the project has made it possible to acquire valuable knowledge regarding the possibilities of managing by-products generated by the fishing industry. We highlight the advances obtained in the optimization of the Subcritical Water Extraction (SWE) method and the treatment with CR11 ion exchange resin. These results open a path to the revaluation of waste from the fishing industry, contributing to reducing the concentration of cadmium and mercury in final fishmeal, without eliminating other components of nutritional interest, such as proteins and micronutrients.

Through the study of key points in the generation and reuse chain, in particular the by-products of the processing industries and their use in the manufacture of fishmeal, the relevant elements on which to act and the stages in which to intervene were identified. The fundamental points to be stressed to reduce the presence of cadmium, the most relevant element in fishery by-products, are the by-product itself in its raw state, after cooking; in solid by-products (press cake); and in the liquid part (cola water).

An extraction technique with pressurized liquids was tested, specifically a Subcritical Water Extraction (SWE) method was optimized by means of an experimental design of response surface, in each matrix of interest, to achieve a separation and fractionation of heavy metals and thus obtain a maximum reduction of their content. The SWE technique and the subsequent concentration of the extracts allowed to reduce the cadmium content in the range of 58-87 % in liquid and gelled by-products.

In addition, other processes were evaluated, such as the treatment of liquid samples with the CR11 ion exchange resin, which achieved a decrease in cadmium of 40-88 %, and the treatment of solid samples with phytic acid, which was discarded as ineffective.

Two alternative pilot processes were also designed, including steps that would allow liquid samples to be partially decontaminated by SWE or with the use of resins during the process of transforming fish by-products in the production of fishmeal.

Subcritical water technology continues to be a technological challenge for the future, which requires adaptation on an industrial scale, without having an impact on an unaffordable increase in the cost of the product, being outside the scope of the project; treatment with CR11 resin, more directly applicable on an industrial scale, would make the process more expensive by requiring reagents, time and “extra” machinery, in addition to the management of the effluents generated. Actual applicability will depend on the balance between commercialability and sustainability.

The following outreach activities have had a major impact:

• Preparation of three press releases in relevant media, dissemination on social networks and corporate websites.
• Presentation in three days:
  • The workshop: R+D+i in species of marine origin was held at the headquarters of CIDAF (Granada), on June 7, 2019.
  • The conference Innovative technologies and solutions to guarantee the competitiveness of the seafood industry was held at ANFACO (Vigo), on November 28, 2019.
  • Participation in the Innovation in Fisheries conference, dedicated to the exchange and transfer of knowledge on innovation in fisheries (Axis 1.1 of the Pleamar Programme), which took place at the Biodiversity Foundation (Madrid) on 30 January 2020, and in which the ELIMET project was presented within the Technologies Block.
• Publication of articles:
  • The project is mentioned in the article Launch of three projects in collaboration with the Biodiversity Foundation, (nº 131, page 51), published in the Industria Conservera Magazine in March 2019.
  • Mention of the project in the article Technology centres, strategic allies in innovation and competitiveness, published in the TECNIFOOD Magazine in June 2019 (nº 123, the mention of ELIMET appears on page 65).
  • Mention of the project in the article Innovative Technologies and Solutions to guarantee the competitiveness of the seafood industry, published in the Industria Conservera Magazine in December 2019 (nº 135, p. 58).
  • Publication of an article about the ELIMET project in issue 17 of Magazine Océano, the Spanish Magazine of the Sea, in May 2020.