Microwave-Assisted Drying of Black Turmeric (Curcuma caesia) Rhizomes: Drying Behavior, Kinetics, Diffusivity, and Phytochemical Analysis

Purpose The study was aimed to evaluate the effect of various drying techniques on drying behavior, curcumin content, and phytochemical properties of Curcuma caesia rhizomes. Methods The hot air oven and microwave drying processes were used for drying of Curcuma caesia rhizomes. Drying behaviors wer...
Ausführliche Beschreibung

Purpose The study was aimed to evaluate the effect of various drying techniques on drying behavior, curcumin content, and phytochemical properties of Curcuma caesia rhizomes. Methods The hot air oven and microwave drying processes were used for drying of Curcuma caesia rhizomes. Drying behaviors were determined using various mathematical models. Phytochemical properties were analyzed using HPLC and LC–MS. Results The Page model was most suitable to illustrate the drying behavior of Curcuma caesia. Microwave drying of Curcuma caesia revealed the lowest activation energy of 3341.8 J/mol and energy consumption with a high moisture diffusivity of 1.48 × $ 10^{−7} $ $ m^{2} $/s. The microwave-dried samples had higher total phenolic content of 41.80 mg GAE/g, total flavonoid content of 486.71 mg QE/g, and total curcumin content of 4.08 mg/g. Furthermore, this sample had increased levels of FRAP and DPPH antioxidant activity. The microwave-dried samples also showed the presence of higher amounts of phenolic acids like chlorogenic acid, caffeic acid, ferulic acid, syringic acid, and gallic acid. In addition, 17 phytochemicals were identified in the microwave-dried samples, whereas 11 compounds were identified in the hot air oven-dried samples. Conclusion The present study demonstrated an approach for the quick drying of black turmeric to retain higher phytochemicals with the desired moisture content. Ausführliche Beschreibung