Off-Odor Removal from Fish Oil by Adsorbent Treatment with Selected Metal-Organic Frameworks

The limiting factor for consumption of liquid fish oil is its fishy off-odor. The objectives of this study were to remove the off-odors from liquid fish oil by adsorbent treatment with selected metal-organic frameworks (MOFs), compare their activity with some natural clays, and also observe other changes developed in the oil after the treatments. Seven synthesized MOFs and three natural clays were added at 0.5% (w/w) into fish oil and mixed for 1.5 h at room temperature prior to filtration. The collected oil samples were analyzed for physico-chemical properties, fatty acid, mineral and volatiles compositions, and sensory descriptions. Results indicated that for all the adsorbents tested, oil physico-chemical properties improved, while no remarkable change was observed in fatty acid and mineral composition. Volatile composition analysis revealed that 68.8%, 46.2% and 44.5% reductions over total volatile concentrations were achieved using gamma-CD-MOF, sepiolite and Ti-MOF adsorbents, respectively. The panel described the oil with fishy, algae-iodine, green and rancid terms. Some significant decreases in the measured sensory attributes were observed after the adsorbent treatments. Overall, although some significant reductions in volatiles were achieved, some off-odor characteristics still remained at perceivable level. Hence, further studies focusing on designing specific MOFs are suggested.