Characterization of the key volatile compounds in longjing tea (Camellia sinensis) with different aroma types at different steeping temperatures by GC‒MS and GC‒IMS

Abstract

Longjing tea (Camellia sinensis), an iconic agricultural product distinguished by its geographical indication status, has gained much acceptance and consumption in China. The aroma types and steeping conditions of green tea are important factors influencing consumer acceptance. However, the effects of steeping conditions on tea samples with different aroma types are still unknown. Explanation of the above unknowns can provide new insights into the flavor variations of tea when consumed for optimal sensory enjoyment. Here, the aroma profiles of Longjing green teas with bean-like (DX) and fresh aroma (QX) types were analyzed using gas chromatography‒mass spectrometry (GC‒MS), gas chromatography–ion mobility spectrometry (GC‒IMS), and quantitative descriptive analysis (QDA). Geraniol, (E, E)-2,4-heptadienal and other 11 compounds contributed to the bean-like aroma, while heptanal-d, hexanal-d and other 4 compounds contributed to the fresh aroma. Further, the release patterns of volatiles at different steeping temperatures were also revealed. 12 volatiles led to the differences between the two aroma types of Longjing teas at different steeping temperatures. Most volatiles exhibited their aroma characteristics when the steeping temperature exceeded 80 °C. These results enhance the comprehension of green tea's aroma profile, thereby enabling consumers to approach tea drinking from a more scientific perspective.