High temperature and high humidity (HTHH) alter flavor properties of Pu-erh tea associated with burnt aroma emergence

The high-temperature and high-humidity (HTHH, 80 °C, 80 % relative humidity) environment has altered the characteristics and flavor of raw Pu-erh tea after 5 days of treatment. The results showed that the colors gradually deepened during the treatment process in five days. Based on sensory evaluation, the roasted aroma and woody aroma of Pu-erh tea were increased with the increase of treatment time. According to the results of gas chromatography–mass spectrometry, the results revealed gradual decrease in floral and fruity aroma compounds, such as (+)-dipentene and linalool. The concentrations of 5-methyl-2-furancarboxaldehyde (caramel) and tea pyrrole (burnt) increased progressively. (E)-2-Octenal, 1-octen-3-one, and 1-octen-3-ol were the key compounds responsible for the mushroom aromas. These compounds contributed to a flavor profile that was comparable to that of ripe Pu-erh tea. Safranal and guaiacol, also identified as key flavor compounds, exhibited herbal and burnt aromas. Subsequently, the reaction mechanism under HTHH conditions was elucidated. This study provides significant data reference guidance in production development of Pu-erh tea.