书城教材教辅科学读本(英文原版)(套装1-6册)
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第106章 第二册(23)

"The pith is first crushed into powder, and then washed and kneaded in water. This presses all the starch out, justas we did out of the flour in the

muslin bag.

"When the water settles, the starch is left at the bottom. It is first partly dried, and then it is pressedthrough a sieve with small round holes."

"Oh, then," said Norah, "this is why we always see it in little round balls.""Quite right," said Fred. "Now let us look at the arrowroot. This too is almost pure starch. It comes from the underground stem of a plant that grows in hot lands. It is got by breaking this stem in pieces, and kneading it up in water, as they knead the sago pith. When dried, it forms this white powder.

"Tapioca is just the same sort of thing. It is almost pure starch. It is got from the root of a plant. The root must be broken up, and treated just like the sago pith and the arrowroot. The starch, that is left at the bottom of the water, is dried onhot plates. As it dries, it is stirred about with an iron rod. This makes it form in lumps as we see it here."SUMMARY