Comparative Studies of Different Drying Methods on Turmeric Slices and Rhizomes: Effect on Drying Kinetics, Quality, Modelling, and Economic Feasibility

ABSTRACT Turmeric drying is a critical post‐harvest operation that affects product quality, shelf life, and market value. Traditional sun drying (widely used in rural areas) is slow and contamination‐prone, while conventional hot air drying (though effective) is energy‐intensive and costly. The existing studies often focus on single drying methods or do not simultaneously evaluate drying kinetics, moisture diffusivity, and quality attributes. This study addresses this gap by systematically investigating turmeric slices (5 and 10 mm) and whole rhizomes under three drying systems such as sun, solar, and hot air at two bed thicknesses (25 and 50 mm). The drying behavior was analyzed using moisture ratio, drying rate, and seven thin‐layer models, with the page model best describing sliced turmeric and the two‐term exponential model fitting whole rhizomes. Effective moisture diffusivity ranged from 7.61 × 10 −11 to 5.81 × 10 −10 m 2 /s highest under hot air drying. The quality assessment revealed that hot air drying achieved superior curcumin retention, oleoresin yield, starch content, and color preservation while solar drying provided a sustainable and cost‐effective alternative outperforming sun drying. The novelty of this study lies in its comprehensive comparison of drying methods integrating kinetics, diffusivity, and quality, and highlighting solar drying as a practical solution for small‐scale and rural processing units. It paves the way for hybrid drying technologies that optimize both efficiency and product quality.