APGC-QTOF-MS-based metabolomics reveals markers associated with grapes quality during postharvest storage at different temperatures.

Postharvest quality monitoring of grapes represents a critical challenge in the global fruit supply chain. Traditional sensory evaluation suffers from time lag, preventing early spoilage intervention. Here, we developed an untargeted metabolomics approach using atmospheric pressure gas chromatography quadrupole time-of-flight mass spectrometry (APGC-QTOF-MS) combined with multivariate analysis to screen for potential freshness-related biomarkers in summer black grapes (Vitis vinifera × Vitis labrusca "Summer Black") subjected to different storage temperatures for 48 h. A total of 497 temperature-responsive metabolic features were detected. After rigorous filtering (p < 0.05, FC > 2, VIP > 1) and confirmation, we refined these to 19 high-confidence biomarkers distinctly associated with storage temperature. Results were cross-validated with Orbitrap Exploris GC (OEGC) data. This study demonstrates a robust analytical method for the discovery of temperature-responsive metabolites in perishable produce. The identified biomarkers and their temperature-dependent pattern provide a promising molecular foundation for future investigations into postharvest supply chain monitoring. However, we acknowledge that the 48-h time point serves as an initial snapshot requiring future time‑course validation.