Response surface optimization and multi-response desirability analysis of vacuum spray drying for Thai functional food powders
摘要
This study optimized a vacuum spray dryer using superheated steam for producing functional food powders from Thai indigenous herbs. Response surface methodology (RSM) with central composite design (CCD) was employed to investigate the effects of hot air volume (55.1–224.9 m3/h) and inlet air temperature (121.7–178.3 °C) on moisture content, product yield, particle size, bulk density, solubility, and liquid feed rate. Analysis of variance (ANOVA) confirmed all quadratic regression models were statistically significant (p < 0.05), demonstrating adequate predictive capability (R² = 0.7890–0.9875). Multi-response optimization identified optimal conditions at 180 m3/h hot air volume and 170 °C inlet temperature, achieving composite desirability of 0.847. The optimized system produced powders with 2.8% moisture content, 86.2% yield, 78 μm particle size, 0.62 g/mL bulk density, and 74 L/h production capacity. Seven Thai herbs including Chrysanthemum morifolium, Zingiber officinale, and Phyllanthus emblica were successfully processed. Bioactive compound analysis revealed that dried powders retained antioxidant activity (IC50 = 1.16–3.28 mg/mL), with the apparent reduction compared to fresh materials (IC50 = 2.31–311.31 µg/mL) primarily attributed to carrier material dilution rather than thermal degradation.