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     Have you heard of the saying "a rotten apple ruins the box"? While it is used as an English phrase to show
how a bad person can influence a group,it has a truthful meaning to it. A rotting fruit or vegetable can in fact lead
to quick spoilage of other fruit and vegetables next to it.
     Food wastage, caused by these rotten fruit and vegetables,is a huge concern. Americans waste nearly 40% of
all perfectly eatable food every year or $ 240 billion worth of food a yearl Grocery stores and supermarkets dump
a third of all produce because it is rotten or has marks and does not look good.
       When a fruit starts to ripen, its cells start releasing a gas called  " ethylene(乙烯)". In  fact, it  causes  theproduction of enzymes(酵素)  that  break  down  chemicals  inside fruits  and  change  starch (淀粉)  to  sugar-thisgives fruits their sweetness. These days , as fruit and vegetables are transported over large distances from farms to supermarkets,they are harvested when they are still unripe. They are then kept in an ethylene-free environment,until they reach their destination where they are exposed to ethylene gas.
    Now,as a fruit starts to be overripe,it will release a larger amount of ethylene. This is picked up by other
fruit and vegetables that are next to it - causing them to ripen faster. So, as you can imagine,a domino effect
happens , causing an entire box to go bad.
A company C2Sense has invented a tiny computer chip called electronic nose, which can sense ethylene in
small amounts - too small for a human nose to smell, and cause an alarm. The company hopes to make these 高考英语模拟试题库  http://www.17xuexiba.com/yy/