Infrared and hot drying of saffron petal ( Crocus sativus L.): Effect on drying, energy, color, and rehydration

Abstract

In this study, the effect of infrared (IR) and hot air dryers on the drying properties of saffron petals was investigated. Drying of saffron petals was done under three level temperature 40, 50, and 60°C and distance from IR lamps 10, 14, and 20 cm and the main physical and thermal properties were measured. The highest value effective moisture diffusion ( D _eff) was evaluated for IR‐dried samples at 60°C and 10 cm with 5.57 × 10 ⁻⁷ m ²/s. The lowest value of color changes is related to the sample dried at 40°C at a distance of 20 cm with a color change of 11.99 in the IR dryer. Increasing the drying temperature reduced the drying time and energy consumption and increased the drying rate and D _eff. Also, the results showed that Midilli model was selected as the best model for drying saffron petals with an IR and hot air dryer.

Practical Applications

Due to the importance and sensitivity of saffron petals to the application of heat in the drying process, it is necessary to dry this product like other medicinal plants scientifically. Theoretical research, with the help of mathematical modeling and numerical simulation, provides a powerful and fast tool for analyzing the process of mass and heat transfer under natural drying conditions. Careful study of the drying kinetics of the product, evaluation of parameters affecting the physical quality properties, and the concomitant and reciprocal effects of these parameters is necessary. It can be used in the drying industry of medicinal plants.