Dynamic effects of ultrasonic treatment on flavor and metabolic pathway of pumpkin juice during storage based on GC-MS and GC-IMS.

In this study, the dynamic effects of ultrasonic treatment (0-400 W) on the volatile flavor compounds of pumpkin juice under different storage periods were investigated systematically using a combination of headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS) techniques. A total of 139 and 46 volatile organic compounds (VOCs) were identified by GC-MS and GC-IMS, respectively. The results indicated that complex changes in volatile components occurred during storage. It was found that the content of key volatile components, such as 2-ethylhexan-1-ol and 1-pentanol, decreased significantly, whereas the content of 1-nonanol and menthol increased in the early stage of storage, resulting in the gradual change of the aroma of pumpkin juice from an initial aromatic fruity aroma to an alcoholic and rancid aroma. In particular, it was noted that the 200 W ultrasonic treatment not only effectively promoted the release of volatile components, but also significantly slowed down the generation of undesirable flavor substances during storage, which had a positive effect on the retention of pumpkin juice flavor. Through multivariate statistical analysis and KEGG enrichment analysis, phenylalanine metabolism was found to play a key role in regulating the formation of volatile flavor compounds, further confirming the potential value of ultrasonic treatment in the preservation and processing of pumpkin juice. This provides important theoretical support and practical guidance for the commercial production and processing technology of pumpkin juice and other fruit and vegetable juices.