在线词典,在线翻译

当香蕉变坏

所属:听力板块 来源:普特英语听力 阅读:3399 次 评论:0 条 [我要评论]  [+我要收藏]

小编摘要:香蕉的表皮细胞,含有一种氧化酵素,平常,它被细胞膜包裹得严严实实,不与空气接触,然而一旦碰伤或受冻,细胞膜破裂,氧化酵素就流出来了,与空气中的氧气发生氧化作用,生成一种黑色的化合物,也就是“丑陋”的黑

当香蕉变坏

Y: So Don, yesterday I was walking down the produce aisle when I saw it--long, ripe,yellow. The perfect banana. It really looked delicious and I had to have it. I took it home and hung it on a banana hanger. The very next morning, it developed nasty brown spots.
D: And you're wondering what gives.
Y: Right. It was a good banana yesterday. What happened?
D: It's no mystery, Yael. Those spots are a natural part of the ripening process. You see, just like all fresh produce, your bananas are alive.They're taking in oxygen to help them convert sugars into energy, and releasing carbon dioxide. This process is called respiration.
Y: I don't know, Don, this banana looks dead to me.
D: Now, the quicker a fruit or vegetable respires, the quicker it ripens. For most fruits,the respiration rate slows down after the initial growth stage and the fruit ripens slowly. The growth and ripening process of bananas, however, is different. Although at first the banana's respiration slows down too, when it's ready to ripen, the banana's pulp releases a chemical that increases respiration. This converts the starches in the banana to sugars and gives it its fabulous taste. And you know how good bananas taste!
Y: Watch it--you're drooling. But what does all this ripening have to do with spots?
D: Well, with all this respiration, the banana eventually processes all the starches available. And that's when it begins to die. Those brown spots are rot and decay.
Y: Poor thing. It just ran out of fuel.
D: Yeah, it's never easy seeing a good banana go bad.

标签:听力文摘
0
2012-01-17 22:47 编辑:pliny
分享到:
关注海词微博:
发表评论:
表达一些您的想法吧!已有0条评论>>
登录,再发表评论
文明上网,理性发言!
您可能还感兴趣的文章:
  • [听力板块]身体,你怎么啦?

    每次生病了,家里人最多说的一句话就是“不吃药怎么行?”。可是,有的时候吃药不一定就对身体有好处,反而有可能会帮助病原体“攻击”我们的身体。今天我们来了解了解一种新的理论“达尔文医学
  • [听力板块]利刃特别在何处

    大家都知道锋利的刀刃的切割性能胜过钝刀,但您知道确切原因吗?刀刃的作用就是把人们用在刀把上的力集中起来。
>>精华推荐阅读
热门评论文章