Drying of borage (Echium amoenum) flowers extract: Optimization of encapsulation and spouted bed drying

In this study, the physicochemical properties of the encapsulated borage flower extract (BFE) powder were investigated under different operational conditions using a spouted bed dryer (SBD). The optimal conditions for producing the desired powder were determined using the response surface methodology (RSM). The central composite design (CCD) was used to model the effect of independent parameters on the physicochemical variables, including total anthocyanin content (TAC), redness ( a* ), chroma ( C* ), moisture content, density, wettability, Carr index (CI), and Hausner ratio (HR). TAC recovery from the extract was satisfactory (31.05–34.34 %), with anthocyanin levels in the dried product at 1.18–2.5 mg/g powder. The powders had desirable moisture content (4.62–8.30 %), cohesiveness (HR = 1.04–1.33), and flowability (CI = 4.28–24.96). Air temperature inversely affected TAC, a*, C* , HR, and moisture but positively impacted wettability and flowability of the powders. The TAC, a* , and C* showed parabolic behavior with pH, initially rising then declining. Increased pH decreased density and cohesiveness but improved flowability of the powders. The maximum TAC (2.59 mg/g) was achieved using multi-objective optimization via the RSM method at 73.93 °C and pH = 1.35. Minimal discrepancies between model predictions and experimental data validated the accuracy of the equations estimating the powder's physicochemical properties.