Abstract: Black jujube was prepared from fresh jujube (Zizyphus jujuba cv. Huping) fruit by five different processes, namely three cycles of steaming and roasting (1), soaking in Maillard reaction products (MRPs) solution, incubation under constant temperature and humidity conditions and roasting (2), soaking in MRPs solution and three cycles of steaming and roasting (3), soaking in polyphenol oxidase (PPO) solution, incubation under constant temperature and humidity conditions and roasting (4), and three cycles of steaming and roasting, soaking in PPO solution, incubation under constant temperature and humidity conditions and roasting (5). The volatile components of black jujube were determined by gas chromatography-ion mobility spectrometry (GC-IMS) and headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and the data were analyzed by principal component analysis (PCA) and cluster analysis (CA) to evaluate the effect of different processes on the flavor quality of black jujube. The results showed that the major volatile components of the as-prepared samples were different. The types of basic flavor substances detected by GC-MS and GC-IMS were basically the same, and 6–10 flavor substances were detected by both methods. Furfural, heptanal, nonal, n-octanal and glacial acetic acid were detected in all black jujube samples. Three cycles of steaming and roasting could enhance the flavor of black jujube. Furthermore, this study demonstrates that GC-IMS can be used to quickly identify and analyze the volatile components of different black jujube samples, which provides a theoretical basis for improving the processing technology of black jujube and understanding its browning mechanism.

Key words: black jujube; volatile organic compounds; principal component analysis; gas chromatography-ion mobility spectrometry; headspace solid phase microextraction-gas chromatography-mass spectrometry