Abstract: In this study, gas chromatography-ion mobility spectrometry (GC-IMS) was used to analyze the volatile substances of onion-covered Nang under six different storage conditions, including low-temperature storage, room temperature storage, vacuum storage at room temperature, oxygen-free storage at room temperature, aseptic storage at room temperature, and oxygen-free and aseptic storage at room temperature. The results showed that 66 volatile flavor compounds were identified from onion-covered Nang, including 9 alcohols, 4 ketones, 18 aldehydes, 4 esters, 3 furans, 1 acid and 27 unrecognized compounds. As storage time increased, the content of volatile aldehydes in onion-covered Nang stored at low-temperature and vacuum remained basically unchanged, while the content of volatile aldehydes showed a decreasing trend under the other storage conditions. Principal component analysis (PCA) and Euclidean distance analysis showed that the types and concentrations of volatile substances on day 0 of low-temperature storage were relatively close to those under the other storage conditions, and the positions of the data points in the PCA plot were gathered together, indicating that the change of volatile substances was not obvious under low-temperature storage conditions. This study can provide useful information for understanding the flavor change of onion-covered Nang during storage.

Key words: storage method; volatile substances; gas chromatography-ion mobility spectrometry; Euclidean distance