Abstract:

In this paper, electronic nose (E-nose) coupled with solid-phase microextraction-gas chromatography-mass
spectrometry (SPME-GC-MS) was used to analyze the aroma components of different levels of vanilla pods originated from
Hainan. Besides, the contents of main aroma components were detected by high performance liquid chromatography (HPLC).
The results indicated that overall aroma of different levels of vanilla pods could be distinguished by principal component
analysis (PCA) of E-Nose data. A total of 75 aroma components were identified through SPME-GC-MS, 67, 65 and 60 of
which were detected in level 1, 2 and 3 of vanilla pods, respectively. The three levels of pods showed the highest vanillin
content of 58.86%, 56.66% and 43.90%, respectively, compared to other aroma components. Significant differences existed
in the relative contents of aromatic species, aldehydes, ketones, acids, alcohols, and heterocyclic substances from different
levels of vanilla pods. Aromatic species were the most abundant aroma compounds of vanilla and their relative contents were
88.99%, 88.35% and 82.55% in level 1, 2 and 3 of vanilla pods, respectively. The HPLC results indicated that compared
with the second and third levels, the contents of vanillin and vanillic acid were higher in the first level of vanilla pods with
values of 3.56% and 0.21%, respectively. The content of p-hydroxy benzaldehyde (0.15%) was higher in the second level
than in the first and third levels of pods. The content of p-hydroxy benzoic acid (0.03%) was the highest in the third level
among the three levels of vanilla pods.

Key words: vanilla pods, aroma, electronic nose, headspace solid-phase microextraction gas chromatography-mass spectrometry