Side-streams of fish and shellfish processing generated in three EU Regions designed for pilot case studies were characterised. All side-streams were analysed for proximal composition. Other analytical parameters were selected following what the European and National regulations on fertilisers establishes for the target end products. Shellfish by-products from the Adriatic and sidestreams from the Baltic case studies were analysed for dry matter, ash, protein, P, Mg, Na, Ca, K, chlorides (Cl-) and sulphates, and microbial pathogens (Salmonella and E. coli). Liquid sidestreams were analysed for total and free amino acid content and salt concentration, while byproducts with a high fat content were analysed also for fatty acid composition and parameters of fat oxidation (TBA, peroxide value and free fatty acids). All side-streams were analysed for
heavy metals (Hg, Pb, As, Cd, Ni, Cu, Cr and Zn, which were found under the established legal threshold levels.
A seasonal variation in the proximal composition of fish processing by-products and a high variability in the protein concentration in the side-streams of the processing companies in the Cantabrian Region were found, which makes expect differences in the process yield in the different fractions.
The mixed side-stream from the shellfish species studied in the Adriatic area is quite homogeneous, which ensures the replicability and stability of the proposed valorisation chain. The measured protein content of the organic fraction confirms the possibility to recover protein hydrolysates from this stream.
The observed compositional variability shall be considered when estimating the expected yields in the scaling up of the processes for obtaining biobased fertilisers from the organic fractions.
Authors: Carlos Bald/AZTI; Corinne Andreola /UNIVPM; Marie Soone /NUTRILOOP
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