Osmotic dehydration assisted impregnation of curcuminoids in coconut slices

Osmotic treatment was explored as a method to infuse curcuminoids in coconut slices. The rate of mass transfer of moisture, solid and curcuminoids with or without application of ultrasound were studied over a range of concentration of osmotic solutions (0–50%). The diffusion coefficient of curcuminoids was 1.64 × 10−10 m2/s, when water was used in place of osmotic solute which was further enhanced by the application of ultrasound to 1.87 × 10−10 m2/s. Increase in the concentration of osmotic solution beyond 25% resulted in reversal in the direction of moisture and solid mass transfer. Ultrasound treatment resulted in higher moisture and solid mass transfer due to the breaking of cell structure as revealed by microstructure examination. HPLC analysis revealed that all the curcuminoids (curcumin, demethoxycurcumin and bisdemethoxycurcumin) were infused into the coconut matrix. The present study concluded that osmotic dehydration is a feasible technology for impregnation of functional ingredients into foods without altering its matrix.