Abstract: This study investigated the effect of brewing temperature on the quality of tea infusions from two types of Cistanche deserticola tea, namely the vacuum freeze-dried upper part and the vacuum freeze-dried and baked lower part of the fleshy stem. The changes in the antioxidant activity and sensory flavor characteristics of C. deserticola tea brewed at different temperatures from 80 to 100 ℃ were examined. The color, echinacoside, acteoside, total phenols, total flavonoids, antioxidant activity, and flavor compounds of the tea infusions were analyzed using various techniques including high performance liquid chromatography (HPLC) and electronic nose. The results showed that the optimal brewing temperature for the freeze-dried type was 85 ℃. At this temperature, the tea infusion exhibited a clear light-yellow color, and 13 flavor compounds were detected; the concentrations of of acteoside (201.07 μg/mL) and total flavonoids (2.43 mg/mL) reached the highest values across all tested brewing temperatures. The optimal brewing temperature for the vacuum freeze-dried and baked type was 100 ℃. At this temperature, 14 flavor compounds were identified, including two unique flavor compounds, 1-hydroxy-2-butanone and 2-ethylhexanol. Echinacoside (175.88 μg/mL), total phenols (0.41 mg/mL), total flavonoids (1.69 mg/mL), and 1,1-diphenyl 2-picrylhydrazyl (DPPH) radical scavenging activity (3.06 μmol/mL) all reached their highest levels. In summary, this study provides theoretical support for processing optimization and proper brewing of C. deserticola tea.

Key words: brewing temperature; Cistanche deserticola tea infusion; flavor compounds; chromatographic techniques; antioxidant activity