Safe to steep? Temporal shifts in microbial viability and functional metabolites define the safety of prolonged dandelion tea

Dandelion (<italic>Taraxacum officinale</italic>) tea possesses significant nutritional and pharmacological value, but the impact of brewing time on its chemical stability and microbial safety remains unclear. This study investigated changes in chemical composition, antioxidant capacity, and microbial community structure in dandelion tea under different brewing durations (1, 12, 24, and 36 h) using metabolomic analysis and 16S rRNA microbiome sequencing. The results showed that prolonged brewing significantly altered the metabolic profile of dandelion tea, with certain heat-stable or water-soluble components being increasingly released or enriched. However, extended brewing led to the loss of nutritional components, a decline in flavor quality, and the potential release of harmful substances. Microbial analysis revealed a decrease in microbial diversity with longer brewing times, with specific bacterial genera (such as <italic>Bacillus</italic>) becoming dominant. Long-term brewing may reduce the functional activity of microbes responsible for the biosynthesis of secondary metabolites, vitamins, and lipids, thereby disrupting the balance of bioactive compounds and potentially weakening the health-promoting properties of the tea. Therefore, it is recommended to consume dandelion tea brewed for less than 12 h to ensure its nutritional value and safety.