Abstract: The effects of microwave vacuum freeze drying (MVFD), microwave vacuum puffing (MVP), short- and medium-wave infrared drying (ID) and vacuum freeze drying (VFD) on the aroma properties of Chinese jujube were determined. The results showed that a total of 70 aroma compounds including alcohols, acids (29), aldehydes (31), esters, hydrocarbons and other miscellaneous compounds were identified by gas chromatography-mass spectrometry (GC-MS) coupled with solid phase micro-extraction in four dried jujube chips. Acids were the major volatile compounds in VFD, MVFD and MVP dried jujube chips, while aldehydes were the major volatile compounds in ID dried samples. There were significant differences in aroma quality among four dried jujube chips. Principal component analysis (PCA) was used to establish a model for aroma quality assessment. The MVP dried product showed the highest sensory scores and best aroma quality, followed by the VFD and MVFD dried products, and the ID dried product was the worst. The aroma quality of jujube chips could be evaluated by PCA method.

Key words: jujube fruits, microwave vacuum freeze drying, microwave vacuum puffing, short- and medium-wave infrared drying, aroma compounds, principal component analysis