A comprehensive review of drying techniques and quality for saffron

Saffron, the dried stigma of the Crocus sativus L. flower, is a highly valuable spice widely used in the Mediterranean and West and South Asia. The stability and quality of saffron are influenced by factors such as harvest conditions, post-harvest handling, and storage. This review addressed technical information gaps and provided guidelines for optimizing saffron drying to ensure the best quality. It covered diverse drying methods, including hot air-dryer, vacuum oven dryer, electric oven drying, hybrid photovoltaic-thermal dryer, infrared dryer, microwave dryer, refractance-window drying, freeze drying, and fluidized bed dryer, emphasizing their impact on the drying process and final product quality. The review also discussed the theory of saffron dehydration and summarized experimental findings from the past few decades. Additionally, it integrated important aspects of saffron production and processing, such as harvesting and pretreatments like pulsed electric field and cold plasma, highlighting the need to control temperature, humidity, and airflow to preserve saffron's valuable bioactive compounds and sensory properties. Ultimately, this comprehensive review aimed to inform and guide saffron producers and researchers in selecting and optimizing drying techniques to maintain and enhance the quality of this precious spice.