Acceleration of Atmospheric Freeze-Drying of Food: Methods, Implications, Commercialization, and Future Directions.

Atmospheric freeze-drying (AFD) is an emerging and cost-effective alternative for drying food and pharmaceutical ingredients, offering lower investment and operational costs compared with vacuum freeze-drying (VFD). However, industrial adoption is limited due to the significantly longer time required, resulting from consistently lower drying rates. This has led to increasing interest in accelerating AFD through various strategies. Several approaches have been explored, which can be classified as thermal methods, enhanced vapor flow, reduction in internal resistance, and other pretreatments. While these methods show some degree of acceleration, understanding their implications and limitations is essential for their adoption in AFD. Despite ongoing research on acceleration methods, the analysis of the commercial presence of AFD suggests a significant gap between research progress and the applicability of these methods. This review offers insight into these acceleration methods and provides some future considerations for research to enhance the viability of the process.