Sat, Apr 18, 2009 - Page 13 News List

WEEKEND SCIENCE 週末科學版: Popcorn science 爆米花科學


Popcorn — no trip to the movies is complete without it. Yet popcorn predates the movies by thousands of years, with ancient South American civilizations fond of the crunchy treat. In recent years, the invention of the microwave has turned popcorn into a snack that is not only delicious, but is also fun and easy to make. But what is the cause of that distinctive popping sound? In today’s experiment you will find out.


What you will need: A bag of popcorn kernels, three bowls, a zipper lock bag, sticky labels and a pencil.



Step 1: Take the bowls and label them as follows: sunlight, freezer and refrigerator. Put exactly 100 kernels in each bowl and 100 kernels in the zipper lock bag. Put the zipper lock bag back in the cupboard and the other bowls in their respective places. Leave for three days.

Step 2: It’s time to cook the popcorn in the microwave, so get all your bowls and notebook together. You are going to record two different results — the length of time for the first pop and the number of unpopped kernels after 90 seconds. You have to test each bowl one by one. Make sure you transfer the kernels in the zipper lock bag to a bowl before you start.

Step 3: Record the time of the first pop and count the number of unpopped kernels after 90 seconds. By the way, unpopped kernels are sometimes known as “old maids.” If any of the popcorn looks edible, eat it!





1. crunchy adj.

嘎吱嘎吱響的 (ga1 zi1 ga1 zi1 xiang3 de5),

鬆脆的 (song1 cui4 de5)

2. pop v.i./v.t.

啪一聲爆裂 (pa1 yi4 sheng1 bao4 lie4)

3. kernel n.

果粒 (guo3 li4),果仁 (guo3 ren2)

4. edible adj.

可食用的 (ke3 shi2 yong4 de5)

5. moisture n.

水分 (shui3 fen4)

6. pressure n.

壓力 (ya1 li4)

步驟三:記錄下第一個玉米粒爆開的時間,並在微波九十秒後計算沒有爆開的玉米粒數量。順道一提,沒有爆開的玉米粒有時被稱為「old maids」(老處女)。如果爆完的爆米花看起來可以吃,就吃吧!



You should have discovered that the zipper locked popcorn popped the fastest and had the least old maids. Depending on the temperatures they were exposed to, the other kernels may not have popped at all.

The reason is simple. Kernels look dry but they are 14 percent water. The moisture is contained within a circle of starch at the center. When microwaved, the water expands and pressure inside the kernels grows, until it pops.

If you chill, freeze or warm up the kernels, the moisture dries out and they can no longer be popped.(John phillips, staff writer)




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