Evaluation of Orchid-Like Aroma Between Different Grades of Taiping Houkui Tea by Solid-Phase Microextraction and Comprehensive Two-Dimensional Gas Chromatography Coupled with Time-of-Fight Mass Spectrometry.

BACKGROUND: Taiping houkui tea won the title of "the King of Green Tea" at the International Tea Exposition in 2004, which had an orchid fragrance but the material basis of the orchid fragrance had not been revealed yet. OBJECTIVE: To investigate the material basis of the orchid fragrance and identify the quality grade of Taiping houkui tea. METHODS: A method was developed for evaluating orchid-like aroma between different grades Taiping houkui tea by solid-phase micro extraction (SPME) and comprehensive two-dimensional gas chromatography coupled with time-of-fight mass spectrometry (GC×GC-TOFMS). The crushed tea sample in a 25 mL headspace bottle was incubated at 90°C for 10 min. Then the gaseous sample was extracted by SPME divinylbenzene/polydimethylsiloxane fiber for 50 min and thermally desorpted at 250°C for 2 min. RESULTS: In total, 735 volatile compounds were determined by SPME- GC×GC-TOFMS and 15 compounds were related to orchid-like aroma. CONCLUSIONS: The high-quality Taiping houkui tea has the orchid fragrance and the low-grade one does not; thus orchid-like aroma can be used as a reference of grades of Taiping houkui tea. HIGHLIGHTS: Thirty different grades of Taiping houkui tea samples were compared and analyzed experimentally, and the results showed that the special aroma substances, which played a key role in grade discrimination of Taiping houkui tea, were found by the statistical method.

Microwave-Assisted Extraction Combined with Ultra-High-Performance Liquid Chromatography and Quadrupole/Q-Exactive High-Resolution Mass Spectrometry for the Determination of Main Flavor Substances in Green Tea.

BACKGROUND: In order to make up for the efficacy of sensory assessment of green tea quality and taste, main flavor substances should be quantitatively characterized based on efficient extraction and frontier determination scheme. METHODS: A new, relatively simple sample preparation and detection workflow has been developed for the quantification and confirmation of flavor substances in green tea by microwave-assisted extraction combined with ultra-high-performance LC and quadrupole/Q-Exactive high-resolution MS system. The method identified main flavor substances (i.e., catechins, free amino acids, and caffeine) that were the main components in the formation of tea taste. After crushing pretreatment, tea was extracted and purified simultaneously in a microwave extraction jar by matrix-dispersed solid-phase extraction. The extracting solution was determined by LC coupled to high-resolution Orbitrap mass spectrometry. RESULTS: In this study, extraction solvent and purification materials were selected, extraction temperature and time were optimized, and the amount and proportion of solid-phase extraction packing were optimized. CONCLUSIONS: The method enabled detection of multiple catechins, amino acids, and caffeine in tea by LC coupled to high-resolution Orbitrap MS, and a database of tea flavor substances was established. HIGHLIGHTS: The method could be used for screening and confirmation of the main flavor substances in tea as well as assisting the sensory evaluation to grade the quality of tea.

Cultural development needs of students in military medical university / 中华医学教育探索杂志

The cultural development needs of contemporary college students generally are displayed as varied contents,rich types and distinctive characteristics.Students in military medical universities shoulder the responsibilities of both soldiers and medical students,their cultural development needs are often in contradiction to military culture,thus bringing challenges to the culture construction in military medical universities.By introducing activities from civilians and soldiers,constructing hidden cultural platforms,improving hardware facilities and other innovative methods,we can actively guide students' ideological direction and play a better culturally educational function of military schools.