Volatile components of essential oils extracted from Pu-erh ripe tea by different extraction methods

Pu-erh ripe tea is one of the main tea products in China, which has a unique woody, chestnut fragrance flavour, distinct from other teas. Because of the largely excessive production capacity, it is now possible and necessary to utilise it to produce tea essential oil. In this study, the extraction efficiency of Soxhlet extraction (Soxhlet), ultrasonic-assisted extraction (UAE), simultaneous distillation extraction (SDE), and steam distillation extraction (SD) for extraction oil of Pu-erh ripe tea was investigated. GC-MS and HS-SPME/GC-MS were then applied to identify the volatile compounds in the essential oils and tea samples. The results showed that the extraction ratios of the essential oil were 0.81±0.01 g/kg (Soxhlet), 0.36±0.01 g/kg (UAE), 0.11±0.01 g/kg (SDE), and 0.59±0.01 g/kg (SD). GC-MS identified 40, 38, 35, and 47 volatile compounds in the essential oils extracted by the different methods, whereas 55 compounds were identified by HS-SPME/GC-MS. Therefore, when both the essential oil extraction rate and oil flavour are considered, the best method is SD.