# Sustainable valorization of fish viscera into omega-3 rich lipids and their functional validation

## TL;DR

This study shows how fish viscera waste can be turned into valuable omega-3 rich lipids with potential uses in nutraceuticals and medicine.

## Contribution

The study introduces a sustainable method to extract and enrich omega-3 lipids from fish viscera using green solvents and urea complexation.

## Key findings

- Autoclave-assisted extraction yielded the highest lipid content (16 ± 0.7%) from Catla catla viscera.
- Urea complexation increased total PUFA from 28.44% to 56.03% and ω-3 fractions to 49.86%.
- PUFA-enriched lipids showed antioxidant, wound-healing, and immunomodulatory properties in vitro.

## Abstract

Fish-processing generates substantial viscera waste that is often discarded or sold at negligible prices, representing both an environmental burden and a missed economic opportunity. This study demonstrates the sustainable valorization of Catla catla viscera through green solvent extraction and urea complexation to obtain polyunsaturated fatty acid (PUFA)-rich fractions. Among extraction methods, the autoclave-assisted approach gave the highest lipid yield (16 ± 0.7%), while the classical Bligh & Dyer method preserved the most balanced PUFA profile (20.16%, with EPA 9.47% and DHA 6.82%). Green-solvent modifications (2-MeTHF and ethanol) maintained yields (~ 9.9%) while enhancing ω-3 PUFA recovery to 19.80%. Subsequent urea complexation increased total PUFA from 28.44% to 56.03% and ω-3 fractions to 49.86% at a 6:1 molar ratio. The PUFA-enriched fraction demonstrated measurable in vitro bioactivities, including antioxidant capacity (IC₅₀ < 0.2 mg mL⁻¹), enhanced wound closure of 78.79 ± 3%, and significant immunomodulation (TNF-α reduced to 112.68 pg/mL; TGF-β1 increased to 571.52 pg/mL) at 50% concentration. A preliminary economic estimation suggests that valorization of viscera into PUFA-rich lipids may substantially enhance value compared with raw disposal, although detailed techno-economic analysis and pilot-scale validation are required to confirm feasibility. This dual demonstration of bioactivity and valorization potential highlights viscera-derived lipids as promising nutraceutical and biomedical resources.

The online version contains supplementary material available at 10.1186/s13568-026-02029-1.