Abstract: We have studied how did 2-Hydroxypropyl β-Cyclodextrin (HP-β-CD) affect the hydrolysis rate constants(k) of fatty acid esters in 38%(V/V) Ethanol solution. The combination behavior between HP-β-CD and fatty acid esters has been discovered. And the way to determine the combination costant(A) between them quantificationally have also been found. In addition, the quantificational mathematic expression between hydrolysis rate constants(k) of ester and the concentration of HP- β-CD (M): k=k′/(1+AM) were deduced and validated. The result showed that HP-β-CD could inhibit the hydrolysis reaction of fatty acid ester.

Key words: fatty acid esters, 2-Hydroxypropyl β-Cyclodextrin, combination constants