Sustainable production of Omega-3-rich fish oil from Tuna by-products using green extraction process

Omega-3 fatty acids are essential for human health, yet the increasing global demand necessitates the exploration of sustainable alternative sources, such as fishery by-products. An innovative and environmentally friendly extraction method, previously applied to small fish by-products, was employed on large fish by-products, particularly tuna soft tissues, utilising green solvents including d-limonene, 2-methyloxolane (2-MeOx), and ethanol. The results indicated that d-limonene and 2-MeOx efficiently extracted omega-3-rich oils, achieving notable concentrations of EPA (4–7%) and DHA (17–28%). However, substantial impurities were detected, attributed to the greater difficulty of purifying large fish by-products, which tend to retain blood and other fluids despite cleaning. This contrasts with previous findings from small fish such as sardines and anchovies, where extraction yielded purer oils with greater ease. These findings underscore the necessity of further optimisation of extraction protocols for larger fish waste. Nonetheless, the preliminary outcomes suggest that, with appropriate refinement, tuna by-products represent a promising and sustainable source of omega-3 fatty acids, contributing to more sustainable fishery resource management practices.