Thermal and Nonthermal Assisted Drying of Fruits and Vegetables. Underlying Principles and Role in Physicochemical Properties and Product Quality

Fruits and vegetables are essential for overall human health and nutrition, and there is a high quest for fruits and vegetables of superior quality. Nonetheless, the preservation of fruit is still challenging due to the high moisture content. Pretreatments have assisted fruit and vegetable drying in improving shelf-life and maintaining quality. However, conventional pretreatments affect the physicochemical properties and product qualities. Therefore, thermal and nonthermal pretreatments followed by drying have been researched to improve and enhance fruits and vegetables’ physicochemical properties. This article evaluates sequential thermal (ohmic, electrohydrodynamic, infrared, etc.) or  nonthermal (high-pressure processing, ultrasonic, pulsed-electric field, etc.) pretreatment technologies and drying in the last 5 years, underscoring their efficiency in augmenting the product qualities of fruits and vegetables. In addition, details of nonthermal and thermal pretreatment technologies are explained, and their success stories, drawbacks, and future studies on improving these technologies are provided. Besides, the safety evaluations of various pretreatments are also delved in. Finally, it is recommended that the next 5 years of research should also explore pulsed light, manothermosonication, ultraviolet light, oscillating magnetic field, thermosonication, and ionization radiation pretreatment to augment dried fruits and vegetables’ product qualities and physicochemical properties. This will help better comprehend the impact of emerging technologies on fruits and vegetables’ physicochemical properties.