Combined ultraviolet-C radiation and L-cysteine treatment improves the post-harvest quality and volatile compounds of edible Lanzhou lily bulbs (Lilium davidii var. unicolor) by regulating reactive oxygen species metabolism

Lanzhou lily bulbs (Lilium davidii var. unicolor) are Chinese traditional edible fruits; however, industrial benefits are limited owing to ineffective post-harvest preservation technology. This study investigated the effect of 4.5 kJ/m² ultraviolet (UV)-C radiation and 2.0 g/L L-cysteine (L-cys) treatment on storage quality and reactive oxygen species (ROS) metabolism in lily bulbs. The combined UV-C/L-cys treatment inhibited the increase in decay rate, weight loss, ∆E^⁎ and reducing sugar content; delayed the decrease of firmness and starch content; retained aromatic volatile compounds; and reduced pungent compounds. UV-C/L-cys treatment reduced H₂O₂ content, O₂^·− production rate, lipoxygenase activity and malondialdehyde content by maintaining high ROS-scavenging enzymes (superoxide dismutase and catalase) activities and substances (total phenolic and ascorbic acid) levels, thereby protecting mitochondrial structure. Mantel test indicated that post-harvest quality and volatile compounds were closely related to ROS metabolism. Hence, UV-C/L-cys treatment can efficiently delay lily bulb senescence by reducing ROS accumulation during storage.