Drying is a critical postharvest preservation technique that determines the microbial safety, nutritional integrity, and sensory quality of fruits. This study evaluates the influence of osmotic dehydration pretreatment followed by freeze-drying (ODFD) on the physicochemical, microbiological, and functional properties of blueberries ( Vaccinium corymbosum ). The combined treatment significantly reduced moisture content (from 83.65 ± 0.89% to 19.62 ± 0.78%) and improved microbial control compared to conventional freeze-drying, while maintaining visual and sensory appeal. Although direct freeze-drying retained higher total phenolic and flavonoid levels, ODFD samples exhibited superior anthocyanin retention (7.57 ± 0.15 mg CE/100 g DW) and increased concentrations of key phenolics such as quercetin and malvidin-glucoside. The osmotic pretreatment modulated cell permeability and limited oxidative and enzymatic degradation, contributing to pigment stabilization and enhanced product quality. Moreover, life cycle assessment revealed a 16% lower environmental footprint and 12% cost reduction for the ODFD process compared with freeze-drying alone. These findings demonstrate that osmotic pretreatment prior to freeze-drying is a sustainable and safe dehydration strategy that enhances the functional quality and shelf-life of blueberries while reducing processing energy demand. • Osmotic pretreatment plus freeze-drying improved blueberry quality and safety. • Moisture reduced from 83.6% to 19.6%, enhancing microbial stability postharvest. • Anthocyanin retention increased to 7.57 mg CE/100 g DW after combined treatment. • Improved sweetness, color, and sensory appeal in osmotically pretreated samples. • Life cycle analysis showed 16% lower footprint and 12% lower total processing cost.
Nemes et al. (Wed,) studied this question.