关键词: 高压脉冲电场, 电子鼻, 普洱生茶, 香气

Abstract: In order to produce high-quality Yunnan Pu’er tea by non-thermal processing, the effects of high voltage pulsed electric field (HPEF) on the aroma quality and aging time of unfermented Yunnan Pu’er tea were studied. Unfermented Pu’er tea made from tea leaves harvested in Lincang, Yunnan during 2015 to 2017 was used as the experimental object. After being pretreated by HPEF, the aroma quality of the tea was evaluated by gas chromatography-mass spectrometry (GC-MS) and an electronic nose system. GC-MS results showed that HPEF had a positive effect on enhancing the aroma quality of Pu’er tea. The electronic nose responses to tea samples undergoing HPEF treatment under different conditions were analyzed by principal component analysis (PCA), linear discriminant analysis (LDA), sensor contribution rate (Loadings) analysis and partial least square (PLS) analysis with the Winmuster software. A voltage of 18 kV, a frequency of 198.4 Hz and a treatment duration of 45 min were found to be optimum for enhancing the aroma quality of tea samples. The tea sample produced in 2015 treated under the conditions of 18 kV, 198.4 Hz and 45 min was predicted to be produced in 2011.2283. The tea sample produced in 2016 treated under the conditions of 18 kV, 120.2 Hz and 60 min was predicted to be produced in 2013.2886. The tea sample produced in 2017 treated under the conditions of 12 kV, 198.4 Hz and 60 min was predicted to be produced in 2012.8051. Accordingly, HPEF contributed to shorten the aging time of unfermented Pu’er tea. This study provides a physical method to improve the aroma quality of unfermented Yunnan Pu’er tea, providing a theoretical basis and technical support for deep processing of unfermented Pu’er tea.

Key words: high voltage pulsed electric field, electronic nose, unfermented Pu’er tea, aroma