retrogradation
noun specialized uk/ˌret.rəʊ.ɡrəˈdeɪ.ʃən/ us/ˌret.roʊ.ɡrəˈdeɪ.ʃən/
[ C or U ] physics （天体的）逆行
movement in a direction that is, or seems to be, the opposite to that of most other stars, planets, etc.
The distance of any planet from the sun may be obtained from a measurement of the arc of retrogradation in a given time. 任何行星到太阳的距离都可以通过测量给定时间内的逆行弧来获得。
The middle of the retrogradation always occurs when Saturn is nearly in opposition to the Sun. 逆行的中间总是发生在土星几乎与太阳对冲时。
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- Add to that volcanic eruptions that coincide with the retrogradation of the sun, and we could get a global cooling.
- Because of the upcoming retrogradation of the sun around the barycentre, she says we can expect to encounter climatic extremes.
- In a systematic astronomy, retrogradations become part of the conceptual structure of the system.
[ U ] chemistry （淀粉）回凝
a reaction in which the structure of starch (= a white substance that exists in large amounts in, for example, potatoes and rice) changes when it cools after being cooked
Retrogradation is a reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves. 当糊化淀粉内的直链和支链发生重排时就会出现回凝反应。
Bread kept in a refrigerator will develop mould growth more slowly than bread kept at room temperature, but will turn stale quickly due to retrogradation. 和放在室温的面包相比，放在冰箱里的面包不容易发霉，但更容易因为淀粉回凝而变质。
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- As soon as bread is cooked and has cooled it begins to go stale. This is caused by a breakdown in the gel structure called retrogradation.
- When steamed Chinese manju are cooled or frozen, they often become hard due to retrogradation of gelatinized starch.
- Hardening or loss of flexibility of tortillas is believed to be due to a physico-chemical change in the starch constituent of tortillas which is known as retrogradation.