摘要
打开一盒酸奶．你常常会发现有一层液体浮在表面。有的人把它拌入酸奶中。有的人则将这层液体倒掉。这层液体究竟是什么东西，它又是从哪来的呢？为了揭开酸奶中这层液体的神秘面纱。让我们往回追溯，去看看制作酸奶的原料牛奶吧!牛奶有两种不同类型的蛋白质。大部分蛋白质是酪蛋白。其余是乳清蛋白。
When you open a box of yogurt, you＇ll often see liquid floating on the top. Some people mix it back into the yogurt; and others drain it off. What is it, and where does it come from？ To solve the mystery of the !iquid in yogurt, let＇s take a few steps back to the milk that yogurt is made of. Milk has two different types of proteins. Most of the proteins are casein proteins, and the rest are whey proteins.
