Effect of Slice Thickness, Boiling and Drying Methods on Curcumin, Oleoresin and Essential Oil Content of Ground Turmeric

A study was carried out to analyze the effect of slicing, boiling, and dryingmethods on the extraction of curcumin, oleoresin, and essential oil contentof ground turmeric. The factors and their levels selected for the study wereslice thickness of 2 mm and 3 mm, boiling methods such as pressureboiling at 0.25, 0.5, 0.75 and 1 kgcm-2. Drying methods including traydrying, microwave drying, and vacuum drying were also evaluated. A threefactorial completely randomized design was used to study the effect ofslice thickness, boiling, and drying methods on curcumin content, oleoresincontent, essential oil content of ground turmeric. Water boiled and sun-driedwhole rhizomes were kept as the control for the study. CO2 variety of turmericwas used for the study. Highest curcumin content (4.35%) was obtained from2 mm thick, unboiled, and vacuum dried slices, and the lowest curcumincontent (2.34%) was recorded from 3 mm thick, 1 kgcm-2 pressure boiledand microwave dried samples. The highest oleoresin content (8.86%) wasrecorded by unboiled, vacuum dried samples while lowest (7.13%) oleoresincontent was shown by 1 kgcm-2 pressure boiled and tray dried samples.The study revealed that unboiled turmeric showed better quality than waterboiled and pressure boiled turmeric with respect to the curcumin, oleoresin,essential oil content. During pressure boiling, the quality got reduced withan increase in pressure. Mechanical drying methods provided better qualityturmeric than sun-dried turmeric. Vacuum drying yielded superior qualityturmeric than other mechanical drying methods.