Are food preservatives bad for you

食物防腐剂对人有害吗？

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Food doesn't last.

In days, sometimes hours, bread goes moldy,

apple slices turn brown,

and bacteria multiply in mayonnaise.

But you can find all of these foods out on the shelf at the grocery store,

hopefully unspoiled,

thanks to preservatives.

食物会变质

几天时间，有时几个小时， 面包会发霉，

苹果块变成褐色

蛋黄酱里的细菌繁殖

但你能在商店里的货架上找到这些食物

希望是没有变坏的

多亏了防腐剂

But what exactly are preservatives?

How do they help keep food edible and are they safe?

There are two major factors that cause food to go bad:

microbes and oxidation.

但是到底什么是防腐剂呢

它们是如何保持食物可食用呢？它们安全吗？

有两个重要的因素会导致食物变质

微生物和氧化作用

Microbes like bacteria and fungi invade food

and feed off its nutrients.

Some of these can cause diseases,

like listeria and botulism.

Others just turn edibles into a smelly, slimy, moldy mess.

Meanwhile, oxidation is a chemical change in the food's molecules

caused by enzymes or free radicals which turn fats rancid

and brown produce,  like apples and potatoes.

Preservatives can prevent both types of deterioration.

微生物就像细菌和真菌

入侵食物，破坏了他们的营养成分

部分细菌会导致疾病

像李斯特菌和肉毒杆菌

其它的只是让食物变味，变小，发霉难看

同时，氧化作用是食物分子的一种化学变化

由酶或者是导致脂肪变臭、食物变色的自由基引起的

就像使苹果和土豆变成褐色（的自由基）

防腐剂可以防止这两种形式的恶化

Before the invention of artificial refrigeration,

fungi and bacteria could  run rampant in food.

So we found ways to create an inhospitable environment for microbes.

For example, making the food more acidic unravels enzymes

that microbes need to survive.

And some types of bacteria  can actually help.

在发明人工制冷技术之前

真菌和细菌可以在食物中疯狂地繁衍

所以我们找到了些制造 一个细菌不可繁殖环境的方法

例如，让食物变的很酸来分解酶

使食物分子能够存活

有些种类的细菌其实可以起帮助作用

For thousands of years, people preserved food using bacteria

that produce lactic acid.

The acid turns perishable vegetables and milk

into longer lasting foods,

like sauerkraut in Europe,

kimchi in Korea,

and yogurt in the Middle East.

These cultured foods also populate your digestive track with beneficial microbes.

几千年来，人们用能来保存食物的细菌

就是可以产生乳酸的细菌

这种酸让易变质的蔬菜和牛奶

变得可以长期保存

像欧洲的德国酸菜

韩国泡菜

中东的酸奶

这种人造食物含有的有益分子还能促进消化

Many synthetic preservatives  are also acids.

Benzoic acid in salad dressing,

sorbic acid in cheese,

and propionic acid in baked goods.

Are they safe?

Some studies suggest that benzoates, related to benzoic acid,

contribute to hyperactive behavior.

But the results aren't conclusive.

Otherwise, these acids seem to be perfectly safe.

很多合成防腐剂也是酸

沙拉酱里的苯甲酸

奶酪里的山梨酸

面包里的丙酸

它们安全吗？

有些研究表明与苯甲酸相关的苯酸盐

会导致人们的多动行为

但结论并非结论性的

此外，这些酸似乎是非常安全的

Another antimicrobial strategy is to add a lot of sugar, like in jam,

or salt, like in salted meats.

Sugar and salt hold on to water that microbes need to grow

and actually suck moisture out of any cells that may be hanging around,

thus destroying them.

Of course, too much sugar and salt can increase your risk of heart disease,

diabetes,

and high blood pressure,

so these preservatives  are best in moderation.

另一种抗菌方法是加大量的糖，例如果酱

或者盐，例如腌肉

糖和盐吸附了分子生长需要的水

真正的吸干了任何细胞生长需要的湿度

因而摧毁了他们

当然，大量的糖和盐会导致一些疾病的风险，心脏病

肥胖

高血压

所以这些防腐剂还是适量为好

Antimicrobial nitrates and nitrites, often found in cured meats,

ward off the bacteria that cause botulism, but they may cause other health problems.

Some studies linking cured meats to cancer

have suggested that these preservatives may be the culprit.

Meanwhile, antioxidant preservatives prevent the chemical changes

that can give food an off-flavor or color.

抗菌剂硝酸盐和亚硝酸盐多存在于熏肉里

它们抑制了能导致肉毒杆菌中毒的细菌，但是他们可能会引起其他健康问题

一些研究把熏肉和癌症联系在一起

称防腐剂可能是罪魁祸首

同时，抗氧化剂能够防止导致食物产生异味

或者变颜色的化学变化

Smoke has been used to preserve food for millennia

because some of the aromatic compounds in wood smoke are antioxidants.

Combining smoking with salting was an effective way of preserving meat

before refrigeration.

For antioxidant activity  without a smoky flavor,

there are compounds like BHT and tocopherol,

better known as vitamin E.

Like the compounds in smoke, these sop up free radicals

and stave off rancid flavors

that can develop in foods like oils,

cheese,

and cereal.

千年来，人们用熏制的方法来保存食物

因为使用木材熏制时产生的一些香味的合成物就是抗氧化剂

在冷冻保存之前，加盐熏制是一种保存肉类有效的方法

如果活性抗氧化剂没有烟熏的香味的话

有些合成物像BHT（一种常用的抗氧化剂）和生育酚

就是大家熟知的维生素E

就像烟熏中的合成物，这些吸掉了一些自由激进分子

避免产生腐臭

可以在一些食物里产生，像油，

奶酪

和麦片。

Other antioxidants like citric acid and ascorbic acid

help cut produce keep its color

by thwarting the enzyme  that causes browning.

Some compounds  like sulfites can multitask.

They're both antimicrobials and antioxidants.

Sulfites may cause allergy symptoms in some people,

but most antioxidant preservatives are generally recognized as safe.

其他的一些抗氧化剂 像柠檬酸和维生素C

通过抑制酶导致食物变黄

帮助食物保持新鲜的颜色。

有些合成物，像亚硫酸盐则是有多重功效

它们兼任抗菌和抗氧化的作用

亚硫酸盐可能会使有些人产生过敏症状

但是大部分抗氧化剂通常被认为是安全的

So should you be worried  about preservatives?

Well, they're usually near the end of the ingredients list

because they're used  in very small amounts

determined by the FDA to be safe.

Nevertheless, some consumers and companies

are trying to find alternatives.

Packaging tricks, like reducing the oxygen around the food can help,

but without some kind  of chemical assistance,

there are very few foods that can stay shelf stable for long.

所以你应该担心防腐剂吗？

它们通常被列在食物成分表的最后

因为它们的分量很少

是由FDA（食品药品监督管理局）通过的安全分量

不管怎样，一些消费者和公司

正在试图找到替代品

通过包装的设计，例如真空压缩减少氧气有利于保存食物

但是没有化学物质的帮助

很少的食物可以长期保存