Metabolomic insights into the browning inhibition of fresh-cut apple by hydrogen sulfide

Hydrogen sulfide (H₂S) is known to effectively inhibit the browning of fresh-cut apples, but the mechanism at a metabolic level remains unclear. Herein, non-targeted metabolomics was used to analyze metabolic changes in surface and internal tissues of fresh-cut apple after H₂S treatment. The results showed that prenol lipids were the most up-accumulated differential metabolites in both surface and inner tissue of fresh-cut apple during browning process, which significantly down-accumulated by H₂S treatment. H₂S treatment reduced the consumption of amino acid in surface tissue. Regarding inner tissue, H₂S activated defense response through accumulation of lysophospholipid signaling and induced the biosynthesis of phenolic compounds. We therefore propose that H₂S inhibited the surface browning of fresh-cut apple by reducing the accumulation of prenol lipids, directly delaying amino acid consumption in surface tissue and indirectly regulating defense response in inner tissue, which provides fundamental insights into browning inhibition mechanisms by H₂S.