英文科学读本 第二册·Lesson 26 Milk, Butter, Cheese

Lesson 26 Milk, Butter, Cheese

While we were talking about the cow the other day, said Norah, "we forgot all about the milk she gives us. Milk forms part of our daily food. We drink it; we put it in our tea, coffee, and cocoa; we use it for making puddings with sago, corn-flour, rice, and tapioca.

I've been thinking that as these starch foods cannot make flesh, perhaps we put milk with them, because the milk can make flesh. Is that so, Fred?

Wait, said Fred, "and I'll show you that you are quite right, Norah.

Did you ever see some milk that had been left to stand for a time?

Oh yes, said Norah. "There is always a thick cream floating on the top."

Well, said Fred, "this cream is a mass of very tiny cells or bags of fat. Each cell is like a little bladder, with an extremely thin skin. In the dairy they skim off this cream to make butter."

Yes, said Norah, "but how do they make the butter, Fred?"

The cream is put into a churn, said Fred. "The dairy-maid keeps on turning the handle to shake the cream about. The object of shaking the cream is to break the thin skin of those little fat cells. When the little bladders break, the fat in them is set free, and forms into a solid lump of butter."

We saw something else in the milk. said Will. "I daresay Norah has often seen milk when it has turned sour."

Oh, yes, said Norah, "I saw some sour milk today. There was something white and thick and solid floating in it."

Well, said Willie, "teacher got some of this stuff out of the milk, by pouring a sour liquid called rennet into it."

But what did the rennet do to the milk? said Norah.

It made some of the milk form into white solid lumps, said Fred. "These lumps are called curds. The rest of the milk is known as whey.

This curd, Fred added, "is the part of the milk which is able to make flesh. You know, of course, that the cow's milk is meant to feed her little calf, till it is able to look after itself. It is the curd of the milk that builds up the growing body of the little calf.

Did you know, Norah, that cheese is made from these curds of milk?

SUMMARY

The cream of milk is a mass of tiny cells or bags of fat. The little bags are broken in the churn, and the fat in them forms butter. The curd of milk is made into cheese.