Abstract
In this work, methyl beta-cyclodextrin (M beta-CD) was used to increase the solubility of turmeric rhizome oleoresin (TRO) in aqueous solution by forming inclusion complexes, and the technique was combined with microwave-assisted extraction (MAE) to extract the curcuminoids from Curcuma domestica Val. Optimized conditions for the MAE were microwave power of 700 W, extraction particle size of 0.30-0.60 mm, extraction time of 3 min, solvent volume of 10 mL, 2 g of sample, and extraction temperature of 60 A degrees C. High-performance liquid chromatography was used for the determination of the curcuminoids. Phase solubility study was conducted to investigate the association of M beta-CD with TRO using curcumin, the major curcuminoid, as a marker compound to represent turmeric oleoresin. The curcumin recovery was increased due to its complexation with M beta-CD. Linear host-guest correlation with slope of < 1 indicated a stoichiometry of 1:1 M beta-CD-complex, and with this assumption, the stability constant, K (C) , was calculated as 515.19 M-1. Meanwhile, the molar ratio needed for inclusion complexation between TRO/M beta-CD was 1:2. Attenuated total reflectance Fourier transform infrared spectroscopy results revealed that the MAE application for the co-precipitation, physical, and kneading methods can all be used for complexation.