Process efficiency of electromagnetic radiation (EMR)‐assisted hybrid drying in spearmint ( Mentha spicata L. )

Recent developments in radio frequency drying for food and agricultural products using a multi-stage strategy: a review

Radio frequency (RF) drying is an emerging technology for food and agricultural products, holding features of rapid, uniform, stable, and volumetric heating, high energy efficiency, and moisture leveling. However, the RF drying with a single stage commonly has drawbacks of unexpected product quality, non-uniform moisture distribution, and prolonged drying time. The multi-stage drying approach could overcome the shortcomings of one-stage strategy accordingly by applying different drying methods or operating parameter values in each phase separately. This review describes the principle of RF heating, presents the typical systems and superiorities of RF drying, and provides a comprehensive overview on recent development in applications of both the one-stage and the multi-stage RF drying, and analysis of drying characteristics and merits for different types of the two-stage strategy. This review finally proposes recommendations for future studies in improving and optimizing the existing RF drying protocols and scaling up them to industrial applications.

Infrared Drying Trends Applied to Fruit

Aims: This article seeks to identify the main products to which drying is applied, mainly by infrared, as well as the mathematical models used to evaluate a product.

Background: The drying of agro-industrial products is a very important unitary operation to avoid post-harvest losses.

Objective: This article looks to respond to the following questions: Which raw materials are subjected to far-infrared drying? What are the mathematical models used in the application of far-infrared?

Method: To identify the most focused articles on the topic, we worked with the search equation “TITLE-ABS-KEY (‘infrared drying’) AND fruits AND [LIMIT-TO (SUBJAREA, ‘AGRI’) OR LIMIT-TO (SUBJAREA, ‘ENGI’)],” which was run in the Scopus database for scientific articles.

Result: After knowing the different technologies, more than 23 applications in agro-industrial products were identified. In these applications, it is observed how quality is one of the most important factors in the preservation of dehydrated products; far-infrared drying helps retain sensory quality in products such as sweet potatoes, grapes, Cordyceps militaris, and mangoes.

Conclusion: A common factor that could be found from the articles and patents was the application of this infrared drying technique in fruits and vegetables with high water content, such as kiwi, chives, and mushroom varieties. These articles and patents based their studies on optimizing the technique by varying drying times, temperatures, and pressures, even sometimes combining different drying techniques—all to preserve the organoleptic characteristics of the product, avoiding damage to thermolabile compounds and obtaining a dry food of very good quality, performance, and characteristics.