Fabrication of a citric acid-crosslinked β-cyclodextrin/silica composite and its selective adsorption of cholesterol from crude fish oil.

A novel β-cyclodextrin-modified silica composite (β-CD-SiO2) was prepared by in situ thermal esterification for selective elimination of cholesterol in tuna oil refining. Characterisations revealed the effective immobilisation of β-cyclodextrin (β-CD) onto mesoporous silica (mean pore size 24.40 nm). The adsorption kinetics and isotherms results were fitted to pseudo-second-order and Langmuir models respectively, indicating spontaneous monolayer chemisorption due to host-guest hydrophobic interactions and hydrogen bonding. In the real refining process, β-CD-SiO2 achieved cholesterol removal efficiency of 42.72% (capacity 54.46 ± 2.44 mg/g), which was better than silica (SiO2) (42.60 ± 1.95 mg/g). Furthermore, the retention rate of vitamin E was greater than 94.9% at 4 h treatment and the sum percentage of EPA and DHA was enhanced from 25.97 ± 1.19% to 29.31 ± 0.31%. Meanwhile, the acid and peroxide levels were considerably lowered (P < 0.05) with increased brightness and color difference. To summarise, β-CD-SiO2 has promising application potential in marine oil refining.