Survey of volatile organic compounds released at different temperatures from tea by direct analysis in real time mass spectrometry

Thermal processing significantly influences tea quality and volatile organic compound (VOC) profiles. This study established an online system combining a controlled heating apparatus with Direct Analysis in Real Time Mass Spectrometry (DART-MS) to monitor the VOCs generated during the roasting of six major tea types. The optimized approach revealed four consecutive stages of volatile release, progressing from initial evaporation to extensive Maillard reaction development. The system successfully differentiated tea varieties based on unique VOC profiles and identified characteristic markers for each type. Moreover, it dynamically tracked key chemical transformations, particularly the temperature-dependent formation of Maillard-derived flavor compounds and related byproducts. Multivariate statistical analysis further confirmed the distinct separation of both tea types and thermal stages. This method allows direct, real-time monitoring of tea roasting dynamics without pretreatment, and the approach demonstrates high reliability and offers a powerful tool for understanding tea chemistry and optimizing thermal processing.