Abstract
<jats:p> Valorization of aquaculture waste into biofuels and biomaterials is crucial to advancing a low-carbon bioeconomy. However, the inherent variability in the fatty acid composition introduces uncertainties in conversion efficiencies during transesterification and poses challenges in chemical processing. Through integration of gas chromatography-mass spectrometry (GC-MS), rheology, transesterification studies, and kinetic parameters associated with the activated flow state (and Eyring analysis), this work investigates the variability in fatty acid composition of ocean biomass-derived oils (fish and microalgae) and its influence on the viscosity of the oil. The findings reveal that salmon ( <jats:italic toggle="yes">Salmo salar</jats:italic> ) oil is high in monounsaturated fatty acids (MUFA), 53.26 ± 7.08%, which correlates to a high viscosity of 39.61 ± 0.01 cP hindering its conversion to fatty acid methyl esters (FAMEs). However, ω-3 fish oil ( <jats:italic toggle="yes">Engraulis encrasicolus and Sardina pilchardus</jats:italic> ) is high in polyunsaturated fatty acids (PUFA) 38.59 ± 2.80%, increasing its conversion to FAME. These 2 findings demonstrate that transport phenomena governed by molecular composition can outweigh intrinsic energetic barriers in determining reaction performance. By directly linking fatty acid composition to rheology and chemical conversion, this work establishes viscosity as a predictive descriptor of feedstock processability, which could lead to increased energy efficiency and rational selection of ocean biomass-derived oils for sustainable chemical manufacturing. </jats:p>