Widely targeted metabolomics analysis reveals effects of raw material parts, harvest season, and processing technology of Huangqin (Scutellaria baicalensis Georgi) tea

Huangqin ( Scutellaria baicalensis Georgi) tea (HQT), a caffeine-free traditional herbal beverage with unique flavor and potential nutritional value, has unclear nutritional component basis, and flavor characteristics. This is the first study to adopt a widely targeted metabolomics approach for analyzing volatile and non-volatile metabolites in six HQT types, and investigating the effects of plant parts, harvest seasons and processing techniques on their flavor and components. Sensory evaluation revealed that fermentation and steaming-sun-drying reduced the grassy aroma, eliminated astringency, and enhanced sweetness, whereas green-tea–style processing retained fresh grassy notes. Metabolomic analysis indicated flavonoids, phenolic acids, and lipids were the main components, and over 200 characteristic aroma compounds were identified. Processing emerged as the predominant factor influencing the metabolites and sensory properties of HQT, followed by the parts of the raw materials, while the seasonal effects were minimal. Fermented tea led to a reduction in total flavonoids but an enrichment of methoxylated flavonoids, aglycones, and sweet and roasted aromas. Shougong tea, which undergoes a nine-cycle processing, accumulated flavonoid glycosides. Sanfu binggan tea with extra steaming and pressing, improved the taste by retaining green and sweet compounds. Non-steamed products, such as Nenye tea, Chunye tea, and Qiuye tea, preserved fresh notes. Among them, NenYe Tea, made from tender leaves, had higher levels of flavonoids (baicalin, wogonoside) and volatile substances. Processing was the dominant determinant of food quality of HQT, providing a basis for targeted food product development and highlighting the need for further research on flavor and nutritional regulation mechanisms. • Fermentation and steaming-sun-drying reduced grassiness/astringency and enhanced sweetness. • Totally 3009 non-volatile and 1835 volatile metabolites were screened. • Flavonoids, phenolic acids, and lipids were the main components in HQT. • Terpenoids and esters were the dominant volatile metabolites in HQT. • HQT quality: processing dominant, plant part secondary, season minima.