What compounds are extracted very quickly by hot-brewed tea, potentially causing bitterness?

Answer

Catechins and tannins.

Hot brewing, steeped briefly in near-boiling water, rapidly extracts catechins and tannins, which can lead to a bitter or astringent taste if not steeped precisely.

What compounds are extracted very quickly by hot-brewed tea, potentially causing bitterness?
preparationbeveragedrinkteasun tea