Abstract: This study was undertaken to evaluate the effect of five different decoloring agents (attapulgite, diatomite, activated carbon, zeolite and activated clay) on the volatile flavor compounds and fatty acid composition of crude fish oil was investigated. Gas chromatography (GC) and headspace solid-phase microetraction coupled with gas chromatography-mass spectrometry (GC-MS) were used to determine the volatile flavor compounds and fatty acid composition of decolorized fish oils. The main flavor components were identified by sensory thresholds. The results showed that the relative contents of nonanal, hexanal, and 2-nonyl ketone, which contributed to the fishy odor and the fatty and waxy aroma, significantly decreased after decolorization, thereby significantly improving the flavor of fish oil. The relative content of saturated fatty acids declined, whereas the relative content of unsaturated fatty acids increased. Acid value and peroxide value rather than iodine value and saponification value changed significantly. The decoloring effects of attapulgite and activated clay were good, while diatomite, activated carbon and zeolite had poor deodorizing effect. The results from the present study will be helpful for improving the decoloring process and the flavor of fish oil in the future.

Key words: decoloring agents, volatile flavor compounds, fatty acid composition, gas chromatography-mass spectrometry (GC-MS), relative odor activity value