Characterisation of odorants in roasted stem tea using gas chromatography-mass spectrometry and gas chromatography-olfactometry analysis

- The potent odorants in roasted stem tea were revealed by GC-O with AEDA.
- The odorant differences between roasted stem and leaf tea were investigated.
- Roasted stem tea was rich in some potent odorants (pyrazines, geraniol and linalool).
- Although tea stem is a by-product of tea processing, roasted stem tea has rich flavour.

Roasted stem tea has a characteristic flavour, which is obtained by roasting tea stems, by-product of green tea production. This research aims to understand the characteristic odorants in roasted stem tea by comparing it to roasted leaf tea. We revealed potent odorants in commercial roasted stem tea using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry with aroma extract dilution analysis (AEDA). The difference between roasted stem and leaf tea derived from the same tea plants were investigated using GC-MS. Pyrazine compounds exhibited a roasted odour and high flavour dilution (FD) factors, as determined via AEDA. Roasted stem tea was richer in these pyrazines than roasted leaf tea. Geraniol and linalool exhibited high FD factors and a floral odour, and roasted stem tea was richer in these compounds than roasted leaf tea. These results may have a positive impact on the development of tea products.