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

Abstract

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 γ‐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.

Development of a New Deodorization Method of Herring Milt Hydrolysate: Impacts of pH, Stirring with Nitrogen and Deaerator Treatment on the Odorous Content

“…Using another adsorption strategy based on the use of zeolites, Song et al (2018) managed to remove 35% of the hexanal content of fish oil originating from tuna and anchovies by-products [ 34 ]. Güner et al (2019) used adsorption on zeolites to remove (E,E)-2,4-heptadienal from fish oil and reached a removal rate of 60% [ 35 ] while in the present case, a total removal of this compound was obtained with the application of the pH 7 -N +D + alkalization pH 10 condition. The pH 7 +N +D condition brought about a decrease in 3-methylbutanal and 2-methylbutanal of respectively 60 and 85% in comparison with the pH 7 after dissolution condition.…”

Impacts of pH and Base Substitution during Deaerator Treatments of Herring Milt Hydrolysate on the Odorous Content and the Antioxidant Activity

“…Using activated carbon, Chen et al (2016) [7] managed to remove 58% of the pentanal in a clam hydrolysate, while, in this study, 70% of this compound was removed. using another adsorption method based on the use of zeolite, Güner et al (2019) [23] removed 60% of the (E,E)-2,4-heptadienal in fish oil, while the pH 7 + D15 + pH 11 KOH + D15 condition managed to remove almost 100% of the (E,E)-2,4-heptadienal content of HMH. Therefore, these results definitely showed the high performance of the combination of deaerator treatments in the deodorization of complex matrices.…”

Characterization of volatile compounds in evening primrose oil after γ‐irradiate

“…Before use, according to the manufacturer's suggestion, the fibre should be 250° at the gas chromatographic injection port within 30 min. The sample (2.5 g) was evenly distributed in a 15 mL headspace vial, and then 1 μL of 2‐methyl‐3‐Heptanone (14 μg/μL in n‐hexane) was added as an internal standard 19 . The sample was equilibrated at 50°C for 10 min, and then the SPME fibre was manually inserted into a vial sealed with a PTFE/silica membrane, adsorbed at 50°C for 30 min, and then thermally adsorbed into the GC‐MS at 250°C for 5 min.…”