Postharvest properties and metabolomic profiling of cucumbers treated with hydrogen sulfide under low-temperature storage.

Cucumbers are highly susceptible to chilling injury (CI) during low-temperature storage, resulting in pitting, water-soaking, tissue collapse, and rapid quality loss. This study showed that exogenous hydrogen sulfide (H2S) effectively alleviated CI in cucumbers stored at 4 °C for 15 d. H2S-treated fruit exhibited lower CI severity, better-preserved color and firmness, and higher soluble protein content than the control. Lipid peroxidation was strongly suppressed, with malondialdehyde 45-49% lower from day 6 onward, accompanied by stronger APX, CAT, and POD activities and higher DPPH and ABTS scavenging capacities during the critical mid-storage period. H2S also preserved bioenergetic competence, as reflected by higher ATP content, higher energy charge, and stronger SDH, Ca2+-Mg2+-ATPase, and CCO activities. Late-stage aerobic bacteria and yeasts/molds were reduced by approximately 1 log CFU/g FW. Metabolomic analysis indicated coordinated remodeling of lipid, central carbon, nucleotide, and GABA-related pathways, supporting improved membrane integrity, redox balance, and cold-storage resilience.