hygroscopic

Bentonite clay is also hygroscopic and absorbs water

膨润土也是一种吸湿剂，可以吸收周围空气中的水分。 在包装和搬运时要特别注意上述材料不能碰水，以免浪费。

But because cake contains more sugar than bread, and sugar is hygroscopic, it retains water better and stays fresh a little longer.

但是因为蛋糕中含有的糖分比面包多，糖又吸湿，蛋糕就保持了充足的水分，所以保鲜的时间长些。