Are spotty fruits and vegetables safe to eat? - Elizabeth Brauer

789,806 views ・ 2016-08-22

TED-Ed


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翻译人员: Weibo Huang 校对人员: 梦佳 庄
00:06
In 2010, $30 billion worth of fruits and vegetables
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2010年,价值三百亿美元的蔬菜水果
00:09
were wasted by American retailers and shoppers
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被美国的商家和消费者白白浪费掉,
00:12
in part because of cosmetic problems and perceived spoilage.
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其中一部分是因为 品相问题和表面的污损。
00:16
That's a poor use of about 30% of the produce on the market,
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这些损失就占到了市场上30%的农产品,
00:20
not to mention the water and energy required to grow and transport it,
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更不用说其生长和运输过程中 所耗费的水电了,
00:24
and the landfill space getting used up by rotting fruit.
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连垃圾场也不得不 腾出空间来倾置腐烂的水果。
00:27
So what are those cosmetic problems?
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那么品相问题是什么?
00:30
You've probably passed over a spotty apple in the grocery store,
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你一定在水果店嫌弃过 带有斑点的苹果,
00:33
or accidentally sunk your thumb into a mushy patch on a tomato.
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或是不小心捏到了番茄上塌软的部分。
00:37
These blemishes can doom produce to the trash can.
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这些污损注定了这样的农产品要被扔掉。
00:41
But what are they anyway,
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但它们究竟是什么,
00:42
and are they actually bad for you?
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对我们真的有害吗?
00:45
Those spots are evidence of an epic battle between plants and microbes.
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这些污损实际上是微生物侵入植物的证据。
00:49
Like humans, plants coexist with billions of fungi and bacteria.
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和人类一样,植物生长的环境 也存在着数不尽的真菌和细菌。
00:53
Some of these microbes are beneficial to the plant,
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有些是对植物有益的,
00:56
suppressing disease and helping it extract nutrients.
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比如抑制病虫害和增强养分吸收。
00:59
Others are pathogens, attacking the produce,
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其它则是病原菌,能够破坏植株,
01:02
still alive as it sits in a store display or your refrigerator
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即使蔬果被摆上了商品架或者 放入冰箱,它们还有残留,
01:06
and siphoning off molecules they can use themselves.
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继续榨取宿主养分以供自己存活。
01:09
The good news is they're almost never bad for you.
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所幸它们对人体几乎是无害的。
01:12
These fungi and bacteria have spent millions of years
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这些真菌和细菌已经用了 几百万年的时间
01:15
developing strategies to overcome a plant's immune system.
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进化出抵御植物免疫系统的能力。
01:18
But healthy human immune systems are different enough
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但是由于健康人体的 免疫系统和植物的大相径庭,
01:21
that those strategies just don't work on us.
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它们的抗免疫能力对我们不起作用。
01:24
So in a plant, what does this process look like?
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那么在植株上, 这一过程是如何发生的呢?
01:28
Microbes can reach plants in a number of ways,
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微生物接触植株的方式很多样,
01:30
like getting splashed onto it during watering or fertilization.
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比如在浇水施肥的时候洒落到植株上。
01:35
Under the right conditions,
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然后在合适的条件下,
01:36
the microbes grow into large enough colonies
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微生物繁殖成大块菌落,
01:39
to attack the waxy outer layer of fruit or leaves.
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并开始破坏水果或者叶片的蜡状表皮。
01:42
Their target: the delicious sugars and nutrients inside.
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它们的目标是内部美味的糖分和养分。
01:46
This type of pathogen often makes spots like this.
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这种病原菌通常会导致这样的斑点。
01:49
A clump of bacteria drains the nutrients and color from the fruit's cells
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凝块的细菌摄取养分 促使水果细胞发生了颜色变化,
01:53
making that yellow halo.
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出现黄色的圆形斑点。
01:55
It then moves outward,
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之后它们向外扩散,
01:56
leaving a black spot of dead cells in its wake.
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在待过的地方留下黑斑状的死细胞。
01:59
Each spot, which could contain hundreds of thousands of microbes
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一个斑点里可能有成百上千的微生物,
02:03
is actually caused by a combination of microbial attack
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实际上这是它们入侵和宿主自卫的过程中
02:06
and the host defending itself.
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共同造就的产物。
02:08
For example, this is the bacterial pathogen Pseudomonas syringae.
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举个例子,这是丁香假单胞菌。
02:13
Once on a tomato, it enters the fruit and leaves,
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一旦接触到番茄, 它就会侵入果实和叶子,
02:16
multiplies in the space between the cells,
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在细胞间隙繁殖,
02:19
and produces toxins and proteins
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分泌毒素和蛋白质
02:21
that allow it to disrupt the plant's immune response.
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从而使植株的免疫反应失效。
02:24
One toxin coronatine makes plants' stomata open up,
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一旦有毒的冠菌素打开了植株的气孔,
02:28
allowing bacteria to enter more freely.
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细菌入侵就畅通无阻了。
02:31
Coronatine also activates pathways leading to chlorophyll degradation,
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冠菌素同时还能降解叶绿素,
02:35
which you can see as yellow spots.
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所以我们才会看到黄色的斑点。
02:37
As the bacteria continue to feed and multiply,
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随着细菌不断得到滋养和繁殖,
02:39
they start to kill off the plant cells.
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它们开始杀死植株细胞。
02:41
That explains spots, but what about mushy blemishes?
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这是斑点的由来,但是 塌软的部分又作何解释呢?
02:45
Those are usually caused when the fruit is attacked by microbes
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它们通常是在果实被微生物入侵
02:49
after it's detached from the plant.
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并且离开后才形成的。
02:50
If the plant is wounded during transport,
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如果植物在运输过程中表面受到破损,
02:52
necrotic fungi can infiltrate through the wound,
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坏死性真菌可以从伤口渗入
02:56
kill the cells,
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杀死植株细胞,
02:57
absorb their nutrients,
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榨取养分,
02:58
and leave your food looking mushy or brown.
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导致食物看起来 呈褐色或者塌软的样子。
03:01
Those spots in particular can taste pretty bad.
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这类斑点尝起来尤其难吃。
03:03
You're eating dead and decomposing tissue, after all.
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毕竟你吃下去的 是坏死和分解后的组织。
03:06
But you can usually salvage the rest of the fruit.
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但是其余完好的部分 还是可放心食用。
03:08
The non-mushy spots, like the ones you typically see on apples or tomatoes,
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你在苹果或番茄上 常见的没有塌陷的斑点
03:13
are just on the surface and don't usually affect flavor.
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只是不美观,但并不影响味道。
03:16
Of course, microbes that do make us sick, like E. coli and salmonella,
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当然,有些微生物是致病的, 比如大肠杆菌和沙门氏菌,
03:20
can hitch a ride on vegetables, too.
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它们也会搭蔬菜的顺风车。
03:23
But because they're not plant pathogens, they don't typically cause spots.
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但是因为它们不是植物病原菌, 所以不会导致斑点。
03:26
They just hang out invisibly on the surface.
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它们只会无形地附着在表面。
03:29
So it's washing fruit and veggies, not avoiding the spotty ones,
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因而正确的做法是清洗蔬果, 而不是避开斑点,
03:32
that will help you avoid getting sick.
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这样才能让你预防疾病。
03:35
So the next time you're at the grocery store,
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所以下一次你再去买水果,
03:37
don't be afraid to pick up funky-looking fruit.
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请放心挑选看上去很丑的水果。
03:39
Some stores will even give you a discount.
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没准老板还会给你优惠。
03:42
Wash them well and store them properly,
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只要洗干净它们,合理贮藏,
03:44
as some produce like apples and cabbages will keep in the fridge for weeks.
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一些农产品如苹果和卷心菜 是可以冷藏保鲜几个星期的。
03:48
The spotty ones may not be eye candy, but they're safe and just as delicious.
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带斑点的蔬果也许不美观, 但它们是安全的,而且同样美味。
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