Yudane

Tangzhong (Chinese: 湯種; pinyin: tāngzhǒng; [tʰáŋʈʂʊ̌ŋ]), also known as a water roux or yu-dane (Japanese: 湯種, romanized: yu-dane; [jɯ̟da̠ne̞]) is a paste of flour cooked in water or milk to over 65 °C (149 °F) which is used to improve the texture of bread and increase the amount of time it takes to stale.
Tangzhong is a gel, which helps stabilize the wheat starches in the bread, to prevent recrystallization which is the main cause of staling. The Chinese characters for the technique translate to "hot water seed".