Production of Instant Linden Tea (Tilia spp.) Powder: Integrating Compound-Level Infusion Kinetics With Response Surface-Optimized Spray Drying

Producing instant herbal teas with consistent bioactive composition requires both efficient extraction and controlled drying to prevent compound degradation. This study developed instant linden tea (Tilia spp.) by integrating compound-level infusion kinetics with response surface-optimized spray drying. Monitoring individual polyphenols during hot-water infusion revealed that extraction at 80°C for 45 min resulted in the highest recovery of major flavonoids and catechins while minimizing thermal epimerization. This optimized infusion was subsequently spray-dried according to a Box-Behnken experimental design to evaluate the effects of inlet air temperature (150°C-170°C), feed rate (6.5-16.5 mL min^-1), and maltodextrin concentration (10%-20%). Inlet temperature and maltodextrin concentration significantly influenced powder yield and antioxidant activity, whereas feed rate had no significant effect on these responses. Multi-response optimization identified optimal conditions at 170°C inlet temperature, 10 mL min^-1 feed rate, and 10% maltodextrin, yielding a powder with 40.33% yield, 3.97% moisture content, 34.39 mmol Trolox g^-1 antioxidant activity, and 109 mg GAE g^-1 total phenolics. HPLC analysis confirmed that the phenolic profile of the reconstituted powder closely matched that of the fresh infusion, with some compounds (catechin, kaempferol, EGCG) showing higher concentrations in the powder due to limited thermal degradation during rapid drying. The resulting powder exhibited excellent solubility (≈99.2%) and was well accepted in sensory evaluation. These findings suggest that integrating compound-level infusion control with optimized spray drying can produce an instant linden tea powder with preserved bioactive composition and functional quality.