On top of the commonly associated bitterness and astringency,
green tea is often associated with having a unique umami taste
quality, which might largely be contributed by L-glutamic acid
and L-aspartic acid. L-theanine (5-N-ethyl-L-glutamine), a non-proteinogenic
amino acid that makes up more than 50% of the free
amino acids content in green tea leaves, has been reported to have
sweet, brothy and umami characteristics, and has also been described
by many studies to be taste-active in green tea