ENCAPSULATION OF LEMONGRASS (Cymbopogon citratus) OLEORESIN WITH β-CYCLODEXTRIN: PHASE SOLUBILITY STUDY AND ITS CHARACTERISATION

Lemongrass oleoresin was successfully extracted from lemongrass (Cymbopogon citratus) using Pressurised Liquid Extraction. The biological active constituent in lemongrass oleoresin is citral or its isomers; geranial and neral is more than 75% by weight of essential oil. Geranial was used as marker compound for this study. The solubility of geranial increased with the addition beta-cyclodextrin until it reached the solubility limit at 7 mM beta-cyclodextrin, with no further improvement after that. The phase solubility diagram obtained was characterised as B-S. Inclusion complex of geranial was prepared by using co-precipitation (CP) and kneading method (KM). Based on phase solubility study, the stability constant, K-1:1, it indicated that molar ratio obtained was 1:1 beta-cyclodextrin (beta-CD):geranial for complexation. The complexes formed were characterised by using Fourier transform infrared spectrometry (FTIR) and differential scanning calorimeter (DSC). The shift of C-H stretching to higher wavenumber and the reduction of intensity of band C=O and C-H band indicated the formation of new solid phase; beta-CD-lemongrass oleoresin. The DSC thermogram showed the new solid phase formed using co-precipitation and kneading methods. The peak intensity of co-precipitation shows the highest compared to kneading. The results obtained from FTIR analysis showed that co-precipitation and kneading methods were able to produce inclusion complex. However, DSC indicates that co-precipitation method able to produce inclusion complex. Therefore, co-precipitation was the chosen method for the formation of inclusion complex between lemongrass oleoresin and beta-cyclodextrin.