The fish product as an example of renewable resource: exploitation and valorization of mullet (Mugil cephalus) skin

The disposal of waste generated by the fish supply chain represents a big environment issue and has a significant economic impact [1]; in a view of a “zero waste” and circular economy, aim of this work is the utilization of industrial fish processing side streams to produce high value bioactive molecules with nutraceutical and cosmetic interest. This work is part of a technical-scientific collaboration between University of Genoa and MICAMO LAB S.r.l., performed as a preliminary proof of concept to a larger research project called EcoeFISHent, a European project funded under the Horizon 2020 - Green Deal Program dedicated to the circular economy in the fishing area, designed to reconcile industrial development, socio-economic growth, and protection of the marine environment [2]. This research focuses on the extraction from fish processing side streams (in this case skins) of acid-soluble collagen (ACS) with an environmentally friendly extraction process [3] such as Pulsed Ultrasound-Assisted Extraction (PUAE) with the aim to improve the extraction yield, that has been compared with a conventional protocol. Mullet skin has been soaked with a solution of NaOH 0.1 M to eliminate non-collagenic proteins, then a defatting with butanol 10% has been performed, therefore acetic acid 0.5 M has been used as extractive solvent and Ultrasounds (US) have been applied to improve extraction yield. The acetic acid solution has been centrifuged and a solution of NaCl (2.3 M in 0.05 M Tris–HCl) has been added to the supernatant to promote collagen precipitation; the precipitated pellet has been resuspended in acetic acid 0.5 M and two different processes, with and without US, have been compared. The extracted collagen has been qualitatively determined by FT-IR spectrum and it has been quantified by Sircol test, a colorimetric assay. Moreover, the biological capacity to promote wound healing is also shown. The results have shown a higher extraction rate in US process respect to the same process without ultrasounds activation. Acknowledgements: EcoeFISHent project (Demonstrable and replicable cluster implementing systemic solutions through multilevel circular value chains for eco-efficient valorization of fishing and fish industries side-streams) Grant agreement ID: 101036428 has received funding from the European Union's Horizon 2020 EU.3.5. Green Deal, Call H2020-LC-GD-2020. 1. [1] V.G. Alfio, C. Manzo, R. Micillo, Molecules 2021, 26, 1002. 2. [2] https://ecoefishent.eu/ 3. [3] A.M.M. Ali, H. Kishimura, S. Benjakul, Process Biochemistry, 2018, 66, 237-244