Cholesterol reduction from milk using β-cyclodextrin immobilized on glass.

β-Cyclodextrin (β-CD) was converted into β-CD-undecenyl ether by chemical modification and subsequently covalently attached to a glass surface. The functionalized glass surface was characterized by static water contact angle and x-ray photoelectron spectroscopy. Both techniques confirmed that an excellent monolayer of β-CD was formed on the glass surface. The β-CD solid surface was used to reduce cholesterol levels in milk. In 4h, 73.6% of the cholesterol was extracted at 25°C with shaking at 170rpm. This is the highest value ever reported for milk using β-CD immobilized on a solid surface. The same surface was repeatedly used for 10 cycles and maintained its efficiency with 72±2% cholesterol reduction observed in all the cycles. X-ray photoelectron spectroscopy analysis completed after 5 and 10 cycles of cholesterol reduction showed that the β-CD on the glass surface was not degraded. The high efficiency and long-term stability of the functional monolayer was attributed to the specific structure of β-CD, which is composed of a relatively low number of functional groups and long spacer chain lengths that provide great flexibility.