Effect of steaming processing on the pulsed vacuum drying characteristics and flavor quality of Polygonatum cyrtonema

This study systematically investigated the effects of steaming processing on the drying characteristics and physicochemical quality of Polygonatum cyrtonema ( PC ). Steaming markedly softened texture and altered its microstructure, promoting the conversion of free water into bound water. As a result, compared with the non-steamed group, the drying time increased by 314.28% after steaming for 240 min. Polysaccharide content decreased by 24.49%, whereas the reducing sugar content increased 3.96-fold, and 5-HMF increased from undetectable levels to 0.33 μg/L, accompanied by enhanced in vitro antioxidant activity and progressive color darkening. Gas chromatography-ion mobility spectrometry (GC-IMS) identified 93 volatile compounds and revealed distinct volatile fingerprints among treatments. Signals of certain alcohols, aldehydes, and esters decreased, whereas those of heat reaction-related pyrazines and furans increased. Electronic tongue analysis showed decreased response intensities for bitterness, astringency, and saltiness but increased richness with prolonged steaming. Overall, steaming affected the drying process and quality formation of PC by regulating tissue structure, moisture state, and component transformation. This study provides a theoretical basis for optimizing the primary processing of PC in production areas.