GWD-10-Q14古埃及人烤面包一小问题~NN来解释啊！

jessicasonia

Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally. The Egyptians, however, did not discover leavened bread until about 3000 B.C. That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.



Which of the following, if true, provide the strongest evidence that the two developments were causally related?


A.Even after the ancient Egyptians discovered leavened bread and the techniques for reliably producing it were well known, unleavened bread continued to be widely consumed.

B.Only when the Egyptians stopped the practice of toasting grain were their stone-lined grain-toasting pits available for baking bread.

C.Heating a wheat kernel destroys its gluten, a protein that must be present in order for yeast to leaven bread dough.加热小麦仁毁坏了的发酵生面团所必须的谷胶

D.The new variety of wheat, which had a more delicate flavor because it was not toasted, was reserved for the consumption of high officials when it first began to be grown.

E.Because the husk of the new variety of wheat was more easily removed, flour made from it required less effort to produce

酵母可以发酵面团为人们所熟知，但是在很多年前，古埃及人只做不发酵的面包，酵母一定是经常被无意中混进生面团中。直到3000BC古埃及人才发现了发酵面包。新引进的小麦品种倍受欢迎，因为不用烘焙这种小麦的麦子仁就可以和麦子皮轻松的被分离。

说明以前分离麦子皮的时候一定要加热，而加热就毁坏了谷胶，所以以前的面包都是没发酵的。

我现在的问题是那么在发现酵母以前他们吃的面包到底是发酵的还是不发酵的啊？如果是没有发酵的，文中为什么还非得提一句说酵母无意中被混进生面团中，那么这样不就是说在发现酵母之前，他们偶尔也能做出发酵的面包了么？

jessicasonia

多谢LZ 如此清晰的解释~！

glaxosmith

C is the answer.

The stimulus says that the discovery of yeast to leaven bread dough happens at the same time that a new variety of wheat was found.  The new wheat is edible without toasting.

The question stem ask you to find an answer choice which support a causation between the two events.

C says that a protein required for yeast to leaven bread dough is destroyed during toasting.  That ensures that before the introduction of the new wheat, yeast could not leaven bread dough made from toasted wheat.  Once the new wheat was found, its edible part could be separated without heating so that the protein required for yeast to work would be present in the bread dough.  This supports the hypothesis that yeast was discovered because a new wheat was introduced.

liulu007

哎 原来是 heating 和 toasting 替换  米有想到啊

bobchowz

发现之前是吃不发酵的面包的——C就解释了为什么发现不了，因为以前的工艺使得酵母即使不小心被混进小麦也无法发酵，所以酵母的作用不被发现，工艺变了自然就发现酵母能发酵。