Characterization of volatile compounds in evening primrose oil after γ-irradiate

Evening primrose oil (EPO) is rich in linolenic acid, which has important physiological activity and attracted more and more attention. As a cold sterilization technology, irradiation is widely used in food preservation. However, the effect of irradiation on the flavour quality of EPO is unclear. The volatile aroma compounds examined by gas chromatography-mass spectrometry (GC-MS), combined with the odour activity value, are used to identify important odours in EPO. Principal component analysis (PCA), cluster heatmap analysis, and orthogonal partial least squares discriminant analysis are used to analyse the data to illustrate the impact of different radiation doses. The results show that the types and composition of volatile substances have changed, among which aldehydes have increased the most. Hexanal, (E,Z)-2,4-decadienal, and (E)-2-octenal, 1-octen-3-ol were confirmed to play an important role in the formation of the green, fast, oily, and fishy aroma profile of EPO. In addition, the cluster analysis and PCA analysis showed that the flavour of 5 and 10 kGy was similar, but it was different from that of 1 kGy. In general, after the irradiation treatment, the flavour quality of EPO deteriorates, and the content of undesirable flavour substances increases. Additionally, the potential formation pathways and mechanism of volatile compounds were discussed. The research will help us to understand the change of the violate compounds under the γ-irradiate process.