Abstract:To investigate the effect of postharvest heat treatment on surface waxes and volatile components of citron fruits， Yunnan citron fruits were immersed in hot water at 50， 55， and 60 ℃ for 3 minutes， 1 minute，and 20 seconds， respectively， with untreated fruits as the control group. Scanning electron microscopy was used to observe the effects of different treatments on the surface wax structure of the fruit， and gas chromatography-mass spectrometry （GC-MS） was used to determine the contents of surface wax and volatile components.The results showed that hot water treatment melted and redistributed the surface waxes of citron fruits， forming a smooth wax film and reducing the formation of fragmented wax from cracks during storage. The surface waxes of citron fruits were mainly composed of alkanes， aldehydes， and fatty acids， with C31 compounds being the most abundant among alkanes， C26 among aldehydes， and C32 among fatty acids. During the middle and late stages of storage， the alkane content in the pericarp wax of heat-treated fruits decreased， while the aldehyde content increased. Especially in the 55 ℃ treatment group， the fruits showed the lowest proportion of alkanes and the highest proportion of aldehydes on day 39 of storage. Among the volatile aroma components on the fruit surface， d-limonene had the highest content， followed by γ-terpinene. The 55 ℃ treatment significantly delayed the decline in the volatile aroma component content， contributing to the retention of fruit aroma. In conclusion， 55 ℃ hot water treatment had a positive effect on the surface waxes and volatile components of citron fruits.