Revolutionizing Liquid Nitrogen Spray Freezing: Core Mechanistic Insights, Multiscale Parameter Effects, and Digital Smart Innovations for Diverse Food and Biomedical Applications

Liquid nitrogen spray freezing (LNSF) has emerged as a promising technology for cryopreservation in food and biomedical applications, offering ultra-fast cooling rates and excellent heat transfer efficiency that preserve structural integrity. Despite its potential, challenges such as unstable cavitation flow, difficulty controlling atomized particle size, non-uniform heat transfer, and material heterogeneity limit its broader application. This review systematically analyzes the core physical mechanisms of LNSF — cavitation, atomization, heat transfer, and ice crystal dynamics — highlighting key controlling parameters including cavitation number ( σ ), Weber number ( We ), Ohnesorge number ( Oh ), and Reynolds number ( Re ). The effects of flow properties, nozzle geometry, ambient conditions, and surface characteristics are examined in detail. We also explore digital innovations that enable a shift from rapid to precision freezing, including multimodal sensing, predictive modeling, and adaptive control. Applications across aquatic products, fruits and vegetables, edible fungi, starch-based products, and biological tissues are discussed, emphasizing how cross-scale coupling between flow dynamics and thermophysical behavior influences freezing efficiency, ice morphology, and product quality. Systematic parameter optimization is shown to enhance freezing uniformity and reduce cryo-damage, charting a clear pathway toward next-generation precision LNSF systems.