Impact of Harvest Timing and Stir-Frying on the Bioactive Compounds, Bioactivities, and Flavor of Ziziphi Spinosae Semen: An Integrated Analysis via GC-IMS, Electronic Sensors, and Caenorhabditis elegans Model

This study investigated the comprehensive effects of harvest timing and stir-frying on Ziziphi Spinosae Semen (ZSS) quality using chemical profiling, Caenorhabditis elegans bioassays, and intelligent sensory analysis (electronic nose (E-nose), electronic tongue (E-tongue), and gas chromatography-ion mobility spectrometry (GC-IMS)). Results indicated that delaying harvest to 15 September significantly promoted bioactive accumulation, with total saponins reaching 9.54 g kg−1 at this stage. Stir-frying the optimal raw material further enhanced pharmacological efficacy; spinosin content increased 1.48-fold, and C. elegans motility cessation time significantly shortened from 240 s to 180 s, demonstrating superior sedative activity. Additionally, stir-frying improved the total sensory score from 53.8 to 80.4, characterized by a harmonized balance of bitterness and umami. GC-IMS analysis identified Maillard reaction products, specifically 2-methylpyrazine and 2-methylbutanal as key markers responsible for the distinctive roasted aroma. Consequently, harvesting the fruits of Ziziphus jujuba var. spinosa at physiological maturity, followed by the stir-frying of ZSS effectively enhances its sedative effects and flavor profile.