Stepwise cellulase-assisted solid-state processing upgrades plantation agarwood powder into a chemically characterized and storage-stable aromatic solid

Low-grade agarwood powder from plantation-grown Aquilaria sinensis (Lour.) Spreng. retains sesquiterpenoids and 2-(2-phenylethyl)chromones, but limited accessibility and rapid volatile loss restrict higher-value use. This study tested whether stepwise cellulase-assisted solid-state processing could improve chemical-marker abundance, time-dependent headspace behavior, and storage stability while retaining the native solid as the product. A divided 0.60% enzyme dose outperformed one-time 0.30%, 0.60%, and 0.90% treatments. Relative to untreated material, the optimized route increased the sum of nine authentic-standard quantified volatiles from 51.98 to 92.18 µg/g dry weight and six chromone-related analytical features from 1.503 to 2.516 mg agarotetrol equivalents/g dry weight. Time-resolved measurements showed an early increase in total reducing sugars and glucose, followed by organic-acid accumulation, pH decline, and later marker enrichment; under the two process-perturbation controls, substantial residual hydrolase activity and carbohydrate mobilization were retained without the full acidification-and-marker-enrichment pattern observed in OPT. Fitted-plateau analysis of the normalized HS-SPME headspace response increased the 25 °C half-plateau time from 10.93 to 17.36 h and reduced the apparent fitted 72 h headspace-response plateau from 82.83% to 71.01%. After 30 d at 40 °C/75% RH, the optimized material retained 77.18% of volatile markers, and three independent 2 kg batches showed low variability in chemical, storage, and material-property endpoints. Stepwise cellulase-assisted solid-state processing therefore provides a reproducible post-harvest route for upgrading plantation agarwood powder into a chemically characterized, storage-stable aromatic solid without an external carrier or preparative extraction.