Review of the Mechanisms, Pros and Cons of Some Drying Technologies Applicable to Agricultural Food Products' Processing

Drying of agricultural food products is an essential unit operation that aims at preventing the alteration of the product's microstructure due to moisture and microbial activities, which invariably deters the shelf life of agricultural food products. This review presents the drying mechanisms of agricultural food products with a critical assessment of drying applications, from first-generation sun drying and shade drying methodologies to contemporary approaches like freeze-drying, infrared drying, microwave drying, spray drying, foam-mat drying, electrohydrodynamic drying, and a combination of some drying technologies like hot air with infrared, vacuum, ultrasound-assisted vacuum, and microwave drying methods. This review also identified the advantages, limitations, and future prospects of each drying application, with a keen interest in the drying time and quality of the agricultural food end products. This review presents guiding information that could aid in selecting a suitable drying method that will not only be relatively economical but will also yield end products with desirable qualities.