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. But what exactly are preservatives? How do they help keep food edible? And are they safe?
食物放不久。過個幾天，有時甚至幾小時，麵包發霉、蘋果片變褐色，而細菌在美乃滋中增生。不過你可以在雜貨店的架上找到這所有食物，但願是沒壞掉的，這都要多虧有防腐劑。可是防腐劑究竟是什麼？它們如何幫食物維持在可食用狀態？防腐劑安全嗎？
There are two major factors that cause food to go bad: microbes and oxidation. 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.
造成食物腐壞的原因主要有兩個：微生物和氧化作用。細菌和真菌那類微生物入侵食物並靠裡面的養分繁殖。這其中一些微生物會引發疾病，像是李斯特菌和肉毒桿菌中毒。其它則只會把可食用的食物變成難聞、黏糊糊又長滿霉菌的噁心東西。同時，氧化作用是酵素或自由基在食物分子中引起的一種化學變化，那會讓脂肪臭酸還會讓農產品變褐色，例如蘋果和馬鈴薯。防腐劑可以防止這兩種腐敗現象發生。
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. 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.
在人工冷藏技術出現前，真菌和細菌會在食物中肆虐。於是我們找尋方法來創造出對微生物不友善的環境。好比說，將食物用得酸一點會破壞微生物存活所需的酵素。而有些種類的細菌其實可以發揮作用。數千年來，人們利用生成乳酸的細菌來保存食物。這種酸將易變質的蔬菜和牛奶變成能存放更久的食物，像是歐洲的酸菜、韓國的泡菜以及中東的酸奶。這些發酵食物也會讓你的消化道充滿好菌。
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 perfectly safe.
許多合成防腐劑也是酸類：沙拉醬中的苯甲酸、起司中的山梨酸，還有烘焙食品中的丙酸。它們安全嗎？有一些研究指出，和苯甲酸有關的苯甲酸鹽會造成過動。不過研究結果並非定論。除此之外，這些酸類似乎十分安全。
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.
其它抗菌策略是添加大量的糖，像果醬，或是鹽，像是醃肉。糖和鹽會抓住微生物生長所需的水份，並真的將周遭任何細胞中的水分吸乾，進而將它們摧毀。當然，太多糖和鹽可能會增加你罹患心臟疾病、糖尿病和高血壓的風險，所以這些防腐劑最好適量添加。
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. 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.
抗菌的硝酸鹽和亞硝酸鹽，常存在醃肉中，能阻擋造成肉毒桿菌中毒的細菌，不過它們可能會引起其它健康問題。一些將醃肉和癌症連結的研究報告指出這些防腐劑可能就是導致癌症的元兇。同時，抗氧化防腐劑防止讓食物走味或變色的化學變化發生。煙燻已經被用來保存食物數千年了，因為木柴的薰煙中有些芳香族化合物是抗氧化劑。將煙燻與鹽一起使用是在冷藏技術出現前保存肉類的一種有效方法。
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.
至於沒有煙燻風味的抗氧化活動，有些像二丁基羥基甲苯和生育酚的化合物，生育酚較常被叫作維生素 E。和煙燻所含的化合物一樣，這些化合物會吸收自由基，並避免可能在油類、起司和穀片那些食物中生成的酸敗味。
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.
其它像是檸檬酸和抗壞血酸之類的抗氧化物，它們會阻擋造成褐變的酵素，讓切過的農產品維持原來色澤。有些像亞硫酸鹽之類的化合物可以同時做許多事。它們既是抗菌劑又是抗氧化劑。亞硫酸鹽可能會讓有些人出現過敏症狀，但大部分的抗氧化防腐劑通常被認為是安全無虞的。
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.
那麼，你應該要擔心這些防腐劑嗎？嗯，它們通常被列在靠近成份表的底端，因為含量非常少，是美國食藥署認定安全的使用量。不過，有些消費者和公司正試著尋找其它可行方案。包裝手法，像是減少食物周遭的氧氣，那會有效果，不過不藉助某種化學輔助，只有很少食物能長期放在架上還不壞掉。
- 「由於、多虧」- Thanks To
But you can find all of these foods out on the shelf at the grocery store, hopefully unspoiled, thanks to preservatives.
不過你可以在雜貨店的架上找到這所有食物，但願是沒壞掉的，這都要多虧有防腐劑。 - 「發酸、腐壞」- Go Bad
There are two major factors that cause food to go bad: microbes and oxidation.
造成食物腐壞的原因主要有兩個：微生物和氧化作用。 - 「以...作食物來源」- Feed Off
Microbes like bacteria and fungi invade food and feed off its nutrients.
細菌和真菌那類微生物入侵食物並靠裡面的養分繁殖。 - 「猖獗、失去控制」- Run Rampant
Before the invention of artificial refrigeration, fungi and bacteria could run rampant in food.
在人工冷藏技術出現前，真菌和細菌會在食物中肆虐。 - 「例如、比方說」- For Example
For example, making the food more acidic unravels enzymes that microbes need to survive.
好比說，將食物用得酸一點會破壞微生物存活所需的酵素。 - 「促成、導致」- Contribute To
Some studies suggest that benzoates, related to benzoic acid, contribute to hyperactive behavior.
有一些研究指出，和苯甲酸有關的苯甲酸鹽會造成過動。 - 「當然」- Of Course
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.
當然，太多糖和鹽可能會增加你罹患心臟疾病、糖尿病和高血壓的風險，所以這些防腐劑最好適量添加。 - 「阻擋、避開」- Ward Off
Antimicrobial nitrates and nitrites, often found in cured meats, ward off the bacteria that cause botulism, but they may cause other health problems.
抗菌的硝酸鹽和亞硝酸鹽，常存在醃肉中，能阻擋造成肉毒桿菌中毒的細菌，不過它們可能會引起其它健康問題。 - 「吸乾、吸收」- Sop Up
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.
和煙燻所含的化合物一樣，這些化合物會吸收自由基，並避免可能在油類、起司和穀片那些食物中生成的酸敗味。 - 「阻止、避免」- Stave Off
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.
和煙燻所含的化合物一樣，這些化合物會吸收自由基，並避免可能在油類、起司和穀片那些食物中生成的酸敗味。
