High-pressure processing reshapes early lipid mobilization in Camellia oleifera seeds during a hot-humid postharvest...

Freshly harvested Camellia oleifera (C. oleifera) fruits may experience a short hot-humid interval before routine drying, yet it remains unclear whether high-pressure processing (HPP) redirects seed lipid mobilization during this early postharvest window.

We established a controlled seed-focused postharvest model in which fruits were subjected to HPP, and pericarps were removed before hot-humid holding to isolate seed-level responses rather than simulate whole-fruit commercial storage. Untargeted UHPLC-Orbitrap metabolomics was integrated with targeted GC-MS quantification of 49 free fatty acids (FFAs) across four regimes: untreated baseline, hot-humid holding alone (35 °C, 95% RH, 12 h), and the same holding step preceded by HPP at 100 or 500 MPa for 5 min.

Forty-two FFAs were detected with high within-regime reproducibility. Hot-humid holding alone caused only modest changes in total FFA abundance, whereas prior HPP converted the same holding period into a pressure-dependent lipid-mobilization response. The 500 MPa regime produced the strongest phenotype, characterized by a pronounced increase in total FFA burden and an unsaturation-enriched C18 free-acyl pool. Untargeted metabolomics further showed that this regime generated the broadest metabolic divergence, although its correspondence with targeted lipid metrics was selective rather than global. Semi-quantitative lipid summaries were compatible with membrane-lipid remodeling and oxygenation-associated metabolism as candidate contributors, but did not resolve the dominant biochemical route.

These findings define a pressure-primed lipid-mobilization window in C. oleifera seeds and identify treatment sequence as a key determinant of early seed lipid trajectories before drying. Further validation under whole-fruit storage, drying, oil-quality assessment, and scale-up conditions is required before this seed-level model can be extended to broader postharvest management.