Drying Kinetics and Quality Characteristics of Saffron Stigmas in a Newly Developed Press Dryer: Bed-Thickness Effects and Contextual Analysis of Published Drying Profiles

Articles in Press

Document Type : Research Article-en

Authors

Reyhaneh Pakdel ¹

Abbas Rohani ¹

Hossein Chaji ²

¹ Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

² Department of Agricultural Engineering Institute, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad P.O. Box 9177335488, Iran

10.22067/ifstrj.2026.99585.1601

Abstract

This study evaluated the drying kinetics and quality characteristics of saffron stigmas using a newly developed press dryer. Drying experiments were conducted at a bed thickness of 2 or 10 mm, and the Newton–Lewis model was used to describe moisture-ratio changes in the experimental and literature-derived datasets. Across the evaluated datasets, the model achieved R² values of 0.96–0.99, although other models provided better fits under some conditions. The press dryer reached the target moisture level in 21 min for the 2-mm bed and 24 min for the 10-mm bed. Quality assessment according to ISO 3632-2 indicated that the dried saffron met Grade I requirements for crocin, safranal, and picrocrocin. Based on equipment specifications and cycle duration, nominal fan electricity use was estimated at 0.525 and 0.600 kWh, and natural gas use at approximately 0.21 and 0.24 m³ for the 2-mm and 10-mm beds, respectively. These energy values were estimates rather than direct measurements. Published drying data were used only for contextual interpretation because the studies differed in materials, equipment, and operating conditions. The findings characterize the press dryer under the conditions investigated.

Keywords

Press dryer, Saffron, Drying kinetics, Crocin, Newton–Lewis model

Subjects

• Food Technology

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