The stability of bioactive compounds in freeze-dried fruits is profoundly influenced by both thermal and structural factors during processing and storage. Freeze-drying, a low-temperature dehydration technique, is widely favored for preserving thermolabile phytochemicals such as polyphenols, flavonoids, anthocyanins, and vitamins. However, even within the freeze-drying process, subtle thermal gradients, sublimation temperatures, and the duration of secondary drying can lead to degradation or transformation of sensitive compounds. Structural characteristics of the fruit matrix, including porosity, crystallinity, cell wall integrity, and the presence of protective macromolecules (e.g., polysaccharides, proteins), play a critical role in shielding bioactives from oxidative, enzymatic, and photochemical damage. Furthermore, interactions between microstructural features and encapsulated bioactives govern their release profiles, shelf-life, and bioavailability. Alterations in the amorphous-to-crystalline ratio during freeze-drying or post-processing recrystallization can further compromise stability. Hence, understanding the synergistic effects of thermal exposure and structural dynamics is essential to optimize freeze-drying protocols, packaging systems, and storage conditions that retain the functional and nutritional quality of fruit-based bioactive compounds.
