**2. What is Chungtaejeon?**

One of the post-fermented teas Chungtaejeon has been developed and inherited from Jangheung in southern coastal areas in Korea over 1200 years ago. It is an international fermented tea, which has a long history from the Three Kingdoms Dynasty to the early modern period of Korea. Chungtaejeon is a kind of Byeongcha (mold). It looks similar to a coin and is called Doncha (shape, **Figure 1**). Also, it is named since its color changes to blue during the fermentation process.

The historical authenticity of Jangheung Chungtaejeon has been recorded on a tombstone in the Borimsa temple. The Borimsa temple served as the main one during the Three Kingdoms Dynasty. On the other hand, Goryeo ran 19 tea spots, and 13 tea spots were in Jangheung [1]. A tea spot is a special production area for tea. Each province ran a national tea farm in the country where tea is well harvested, and the province governor offered tea as a tribute to the king. Also, Jangheung made the best tea of the country during Joseon Dynasty. Nowadays, Chungtaejeon, which is world recognized as a luxury tea, has been approved as registered one for art of taste (2013), selected as "slow food organization" by international life varieties foundation (2014), Japanese international green tea competition best gold medal (2008), gold medal (2011), best gold medal (2014), gold medal (2015 and 2019) and national important agricultural inheritance (2018) [1].

**Figure 1.** *The shape of Chungtaejeon of Korean traditional post-fermentation.*
