Physio-Chemical Analysis of Turmeric Rhizomes (Curcuma Longa L.) Preserved Through Non-Thermal Technique: Electrohydrodynamic Drying

Abstract

The preservation of turmeric rhizomes (Curcuma longa L.) through non-thermal drying techniques has gained significant attention due to its ability to retain bioactive compounds and overall quality. This study investigates the physio-chemical properties of turmeric rhizomes preserved using Electrohydrodynamic (EHD) drying at varying electrode distances (7 cm, 5 cm, and 3 cm) under a voltage of 24 kV, 17 kV and 14 kV respectively. The effects of EHD drying on porosity, shrinkage ratio, rehydration ratio, colour attributes, and curcumin content were evaluated. The results showed that porosity remained consistent across all treatments (65.3–65.49%), indicating uniform drying. Shrinkage ratios ranged from 67.133% to 68.531%, with no significant differences observed, suggesting minimal structural damage during drying. The rehydration ratio was significantly influenced by electrode distance, with the highest ratio observed at 3 cm (313), indicating better water retention and texture. Colour analysis revealed that the dried turmeric retained a colour closest to the fresh sample at 3 cm, while drying at longer electrode distances (5 cm and 7 cm) resulted in increased yellowness and reduced redness. Curcumin content was best preserved at the 3 cm distance, with a significant reduction observed at higher distances. Overall, EHD drying proved to be an effective non-thermal method for preserving the quality, colour, and bioactive compounds of turmeric rhizomes, particularly at shorter electrode distances, offering a promising alternative to traditional thermal drying methods for maintaining the nutritional and therapeutic properties of turmeric.