书城外语英国学生科学读本
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第106章 面粉与面包(1)

1.Let us buy a pound of flour at the baker‘s.The baker will give us the flour in a nice paper bag,and it will only cost about twopence.When we open the bag,we see that the flour is a fine white powder.

2.Where did the flour come from,and how was it made ?There are several kinds of flour-such as oat-flour,barley-flour,rice-flour,and maize-flour or corn-flour.But most of the flour used in Great Britain is wheat-flour.

3.Wheat-flour,of course,comes from the plant called “wheat.”The farmer sows the wheat in his ploughed fields in the late autumn or in the early spring.When the wheat plant comes up,it looks like a little blade of grass.During the summer the plant grows tall,with a long,hollow stem,and a head or ear of little green scaly flowers.They do not look much like flowers,as they have no brightly-coloured leaves.Each flower turns into a seed orgrain,which becomes hard and round asWHEAT(小麦)it ripens.When it is ripe,it turns yellow.Then the farmer cuts it down,or “reaps”it.

4.He carries the wheat to his barn,and there he thrashes it,or beats all the grains of corn out of the ears.The corn is then put into sacks and sold to a man called a miller.

5.The miller grinds the corn between two large fiat stones which are called mill-stones,or between steel rollers.The husks or skins of the grains of corn are first rubbed off,and then the white inside or kernel of each grain is ground down to a fine powder.

6.This powder has to be sifted①,to separate the husks fromthe flour.The husks are hard and coarse,and they would not be good food for us,for we could not digest②them.Last of all,the miller puts the white flour into sacks,and sells it to the baker.

7.Shall we try to find out what wheat-flour is made of?Put a handful of the flour into a small bag made of fine muslin:tie up the mouthof this bag tightly,and then squeeze it for about five minutes in a basin of water.You will see that the water becomes quite white.Something must be coming out ofthe flour and passing through the muslin into the water.What can it be?

8.Let the water in the basin stand for an hour,and you will then find a white powder at the bottom.Pour off the water,and put the white stuff into a saucer to dry on the hob or in the oven.If you mix a little of this dry white powder with a spoonful of boiling water,it swells up into a jelly just like starch;indeed,the white powder is starch and nothing else.So we see that flour contains a great deal of starch.

①Sifted,strained;separated as with a sieve.

②Digest,change or dissolve in the stomach.

9.Now open the muslin bag in which you washed the flour.Is there anything left inside it ?Yes;there is a small quantity of a yellowish-white and very sticky substance.The proper name for this sticky stuff is gluten.We may say,then,that flour consists of starch and gluten.But it also contains some water,and a very little lime which the roots of the wheat plant sucked in from the soil.

10.Of what use is flour?Every child knows that it is made into bread and puddings and pastry.To make bread,we must mix the flour with some water,to which yeast or barm has been added,and a little salt.When these are all kneaded①together with thehands,they form a tough and elastic mass of dough.

11.This dough is left in a warm place for about twenty minutes,to give it time to swell or rise.Then it is cut into pieces,each big enough for one loaf,and these loaves are baked for about two hours in a hot oven.

12.Have you noticed how porous②

or spongy good bread is?This is due

to the fact that the yeast produces a

LOAF OF BREAD(一块面包)

YEAST(酵母)

kind of gas,called carbonic acid gas,inside the dough.The heat of the oven drives this gas out of the bread;and as it makes its way out,it forms little holes and passages or pores in the bread.

13.Yeast is a very curious substance.It isreally a cluster of plants;but each plant is so small that we cannot see it without the help of a microscope.③These plants grow very fast in the dough;and as they grow they produce a great deal of carbonic acid gas,which makes the dough rise.

①Kneaded,mixed;worked or shaped by pressure,especially with the hands.

②Porous,full of very small open-ings.

③Microscope,an instrument for viewing very small objects.

14.When you eat the bread,what good does it do you ?The gluten goes to form your muscles or flesh,the lime hardens your bones,and the starch warms your body and gives you strength for your work.So bread,you see,is a good food,as it contains nearly everything that you need to nourish your body.

SUMMARY

Wheat is sown in the late autumn or early spring.When the plant first comes up it looks like a blade of grass.When ripe it turns yellow and the seeds are hard.After it is reaped the ears are removed by thrashing,and the grain is ground and sifted.Flour is made up of starch,gluten,water,and a little lime.To make bread the flour is mixed with water,yeast,and a little salt.The pores seen in good bread are made by the escape of the carbonic acid gas produced by the yeast.The gluten in the bread makes flesh and muscles,the lime hardens the bones,and the starch keeps the body warm.

【中文阅读】

1.我们去面包房买上一磅面粉。他们会将面粉装在精致的纸袋中,而且一磅面粉只需两便士。打开袋子,就能看到面粉是一种细致的白色粉末。

2.面粉从何而来?又是如何制成的呢?面粉的种类有很多,例如燕麦粉、大麦粉、米粉、玉米粉。然而,英国使用的大部分面粉都是小麦粉。

3.小麦粉当然就是由一种名叫“小麦”①的植物制成。晚秋或早春时分,农民们在犁过的农田里种下小麦。小麦破土而出时,看起来就像是野草一样。到了夏天,小麦就已经长得很高了,带着一个长长的中空茎干以及一簇或一穗绿色的鳞状小花。它们看起来并不像花朵,因为没有颜色明亮的花瓣。每一个花朵都会长成种子或谷粒,一旦成熟,就会变得又硬又圆,而颜色则会泛黄。随后,农民们就会将其割下,或者说是“收”麦子。

4.农民将麦子运到谷仓并打谷②,也就是将谷粒从麦穗中敲打出来。随后,农民将这些谷物捆装在麻袋中贩卖给磨坊主。

5.磨坊主使用两块扁平的石头(磨石)或钢辊对这些谷物进行碾磨。谷物的外皮首先掉落下来,然后,里面的白色谷粒就被碾磨成了精细的粉末③。

6.然后,人们利用筛子将面粉与外皮分离。外皮坚硬且粗糙,我们消化不了,因此不适合用作食物。最后,磨坊主将白色的面粉装在麻袋中销售给面包房。

7.你是否想要知道小麦粉是由什么构成的呢?拿起一把面粉,放入精致的棉布中;将棉布做成口袋装并收紧袋口,然后在一盆清水中用力挤压五分钟。你会发现清水将变成非常浓厚的白色。肯定有什么东西从面粉中分离出来,透过棉布进入了水中。到底是什么呢?

8.将盆中的水静置一小时,就会看到水底有一层白色粉末。将水倒掉,把白色物质放入浅碟之中,利用铁架或火炉进行烘干。如果你将少量这种干燥的白色粉末与一勺开水相混合,它就会像淀粉一样膨胀成胶状物;实际上,这种白色粉末正是淀粉。由此我们知道,面粉中含有大量的淀粉。