听力文摘：什么是鲜奶油？（在线收听）

What Is Whipped Cream?

什么是鲜奶油？

It adorns ice cream sundaes, pumpkin pie, gingerbread, and hot chocolate. Its sweet creaminess tantalizes taste buds and sends dieters running from the scale. Did you ever wonder why heavy cream whips into soft, light peaks? You can find out by listening today's moment of science!

它用来装饰冰淇淋圣代，南瓜派，姜饼和热巧克力。它甜美的口感刺激着你的味蕾，使得节食者也趋之若鹜。你有没有想过为什么多脂奶油被搅成既柔软又轻盈的山峰的形状？你可以收听今天的片刻科学来找到答案。

When you whip heavy cream, air is forced into the liquid, and a stable mass of bubbles forms. Each bubble is a tiny pocket of air encircled by a thin film of water with proteins and other substances dissolved in it.

当你搅拌多脂奶油，空气被迫进入液体，稳定的大量的泡沫形成。每一个泡沫是被一层很薄的水包围的一小口袋的空气，水中有蛋白质，还溶解其它物质在里面。

The protein molecules that are caught in the bubbles are pushed and pulled by different forces, so they lose their normal shape. Once they lose their normal shape, the protein molecules bond together into a thin film, which stabilizes the bubble walls.

泡沫中的蛋白质分子被不同的力量推与拉，所以它们变形了。一旦它们变形了，蛋白质分子结合到一起形成一层固定泡沫的薄墙。

The proteins that stabilize whipped cream are the same as milk proteins, so it would seem that milk would whip into soft shiny peaks as well. But you could whip a bowl of milk all day and never get anything more than a light froth that would disappear almost immediately.

固定鲜奶油蛋白质和牛奶蛋白质类似，这样看来牛奶也应该可以搅成柔软有光泽的山峰。但是你可以搅拌一桶牛奶一整天，发现除了转瞬即逝的小泡沫外就不会有别的了。

The difference lies in whipping cream’s high fat content. Whipping cream is from thirty to forty percent fat, in contrast to the four percent fat found in whole milk.

搅拌奶油中的高脂肪是两者的不同点。一个是30%到40%奶油的搅拌，一个是在4%在全脂牛奶中。

The fat molecules in cream form a strong, stable network that keeps the bubble walls from collapsing. Small spheres of fat molecules gather together in the bubble walls, where surface forces break open the sphere. The exposed fat molecules stick to each other, and the network forms.

奶油中的脂肪分子形成强有力，稳定的网络，可以避免泡沫墙消失。小球体的脂肪分子在泡沫墙中聚到一起，暴露在外的脂肪分子相互粘着，网络形成。

The fat molecules in milk act similarly, but there aren’t enough of them to stabilize the milk foam for more than a few seconds.

牛奶中的脂肪分子也是这样，但是没有足够多的分子可以固定牛奶泡沫超过几秒钟。