Steam Explosion Enhances the Powder Property, Instant Solubility, and Diffusivity of Superfine Ground Tea Powder

Low-grade tea, often underutilized due to its coarse texture and limited bioavailability, represents a significant resource waste. This study systematically investigated the synergistic effects of steam explosion (SE) and superfine grinding on enhancing the structural deconstruction, powder property, instant solubility, and diffusivity of low-grade. SE treatment induced critical physicochemical modifications, including hemicellulose degradation, lignin recondensation, and cellulose crystalline reorganization, which significantly weakened the lignocellulosic matrix. Subsequent superfine grinding via ball milling achieved ultrafine particles, with median diameter <i>D</i>₅₀ = 10.4 ± 0.17 μm, and almost completely destroyed the cell wall by 99.9%. Extraction kinetics revealed that SE-ball milling synergistically accelerated the diffusion behavior of bioactive compounds, reducing equilibrium time by 2~4 times and increasing maximum yields of polysaccharides, polyphenols, caffeine, and water-soluble solids by 9~25% compared to untreated samples. Homogenization combined with 0.08 mg/mL CMC-Na further improved the suspension stability of tea powder and reduced its centrifugal sedimentation to 9.85%. These findings demonstrate a scalable strategy to transform low-grade tea into high-value ingredients with enhanced accessibility and solubility of bioactive compounds, offering promising applications in instant beverages, fortified foods, and nutraceuticals.