Fabrication and characterization of ethyl acetate-hydroxypropyl-β-cyclodextrin inclusion complex

Flavors play crucial role in food industry. Ethyl acetate, as probably one of the most used of all flavor chemicals by volume, is used widely in many industries. However, ethyl acetate is not too stable and can be slowly decomposed by moisture. Furthermore, ethyl acetate is a volatile liquid insoluble in water and it does not last long enough. In order to solve these problems, hydroxypropyl-β-cyclodextrin was used as wall material to encapsulate ethyl acetate in this work. The product was characterized by Fourier transform infrared (FTIR) spectroscopy and thermalgravimetric analysis (TGA). The results showed that the peaks at 1,744 and 1,056 cm^-1 in the FTIR spectrum of ethyl acetate disappeared in the FTIR spectrum of ethyl acetate-hydroxypropyl-β-cyclodextrin inclusion complex. After the encapsulation of ethyl acetate, the O-H and C-H stretching absorption of hydroxypropyl-β-cyclodextrin changed. The TGA results showed that from 77°C to 292°C ethyl acetate is released from the ethyl acetate-hydroxypropyl-β-cyclodextrin inclusion complex in temperatures far beyond ethyl acetate 77°C boiling point. This phenomenon confirmed that the lastingness and thermal stability of ethyl acetate can be improved by the formation of an inclusion complex. The loading capacity of ethyl acetate was 4.86 ± 0.08% and ethyl acetate:hydroxypropyl-β-cyclodextrin stoichiometry is close to 1:1. The interaction of ethyl acetate and hydroxypropyl-β-cyclodextrin was investigated using molecular mechanics calculation. The binding energy was calculated and the possible conformation of ethyl acetate-hydroxypropyl-β-cyclodextrin inclusion complex was optimized to the minimum energy. The binding energy minimum is at the 0.44 × 10^-10  m point and its value is -103.9 kJ/mol. PRACTICAL APPLICATION: Encapsulation of ethyl acetate in hydroxypropyl-β-cyclodextrin is a possible way to protect ethyl acetate, improve its stability, water solubility, and may also enhance its lastingness.