Low-oxygen storage modulates fruit flavor formation: Metabolic and regulatory insights

Controlled atmosphere prolongs fruit storage period by reducing oxygen availability, thereby suppressing respiration, ethylene production, softening, and physiological disorders. However, low oxygen can compromise flavor, a critical attribute for consumer acceptance. This review summarizes current knowledge of how hypoxic storage influences sugar and acid metabolism, volatile biosynthesis, and associated molecular mechanisms. Low oxygen promotes sucrose breakdown and increases glucose and fructose accumulation, while suppressing acid degradation. However, volatile production is reduced through inhibition of fatty acid oxidation and lipoxygenase activity. Anaerobic metabolites such as ethanol and acetaldehyde may provide temporary fruity notes but often reduce aroma complexity during prolonged storage. These shifts are driven by hypoxia-responsive genes including but not limited to alcohol dehydrogenase and pyruvate decarboxylase, which are probably regulated by ERF-VII transcription factors. Integrating big data-driven approaches with precise controlled atmosphere technologies will be essential for developing storage strategies that better balance shelf life extension and flavor preservation.