Thin‐Layer Drying Kinetics and Bioactive Compound Retention in Saccharina latissima : Implications for Scalable Seaweed Processing

Drying is a critical preprocessing step for stabilizing seaweed biomass and shaping its functional quality for food, nutraceutical, and biorefinery applications. This study evaluated the drying behavior of Saccharina latissima under oven drying (OD), air drying (AD), and freeze drying (FD) by combining thin‐layer kinetic modeling and the analyses of phytochemical composition and antioxidant activity. The three methods exhibited distinct drying behaviors where OD showed rapid moisture removal, reflected by the highest drying constant and effective diffusivity, driven by high vapor pressure gradients and strong internal diffusion. AD proceeded slowly under low‐temperature, low‐convection conditions, exhibited by its slow kinetics and lowest diffusivity. FD followed a two‐stage pattern characterized by fast sublimation during primary drying and slower desorption of bound water during secondary drying. These behaviors were reflected in model performance, with the Lewis model best describing OD, the Page model for AD, and the logarithmic model for FD. These differences corresponded to distinct compositional outcomes, wherein OD yielded the highest total polyphenol and flavonoid contents and antioxidant capacity, while FD preserved moderated levels and AD yielded the lowest. This study establishes process–structure–function relationships linking drying mechanisms with bioactive compound recovery in S. latissima , providing a framework for selecting and optimizing drying strategies in seaweed processing.