Turmeric (Curcuma longa) drying in natural circulation solar dryer: An experimental evaluation

Abstract

A natural circulation solar dryer has been evaluated for drying differently processed turmeric. The predrying treatments namely, hydrothermal treatment using water boiling and steam boiling; and drying methods namely, drying of sliced and unsliced turmeric rhizomes have been investigated. The open sun drying and untreated unsliced turmeric rhizome was used as control. The maximum thermal efficiency of this passive solar dryer has been obtained as 22.4% for the water boiled sliced turmeric, and while that for the steam boiled unsliced turmeric was 14.1%. The thermal efficiency was comparatively lower for untreated turmeric. The quality parameters namely, polishing loss, curcumin content, volatile oil content, total recovery, and color, were found better for steam boiled unsliced turmeric dried in solar dryer. Based on combined perspective of thermal efficiency and quality, drying of unsliced rhizome pretreated with steam in natural circulation solar dryer is recommended as compared to other processing practices. The dryer is economically feasible as indicated by the cumulative present worth of life cycle savings and payback period.

Medicinal Plant Drying Using a Superabsorbent Polymer Dryer Incorporated with an Insulated Heater

“…The drying of turmeric in a natural circulation solar dryer requires 60.5 h and 66 h to reach a moisture content of 10%, investigated for water-boiled and steamboiled turmeric, respectively. The average dryer temperature varies from 44 to 65 • C at an ambient temperature of 39-43 • C [62]. Based on the studies obtained from the literature, our Polydryer incorporated with the heater offers a promising option for medicinal plant drying that is efficient and implementable.…”