Swiss cheese its holes?

瑞士起司為什麼有孔洞？

And what makes vinegar so sour?

什麼讓醋變得這麼酸？

These foods may taste completely different,

這些食物嚐起來可能完全不同

but all of these phenomena come from tiny organisms chowing down on sugar

但是所有的現象 都來自微生物分解糖分

and belching up some culinary byproducts.

並且釋放一些食物的副產品

Let's start with yeast.

讓我們從酵母開始

Yeast are single-celled fungi used to make bread, beer, and wine,

酵母是一種單細胞真菌 用於製作麵包、啤酒、葡萄酒

among other products.

以及其他產品

Yeast break down carbohydrates, like sugar,

酵母分解碳水化合物，像是糖

to get energy and the molecules they need to function.

以獲得它們運作時所需的能量和分子

They have two different ways to do this:

它們有兩種不同方法進行

the oxygen-dependent, or aerobic, pathway,

一種是倚靠氧氣的方法，或「有氧」途徑

and the oxygen-independent, anaerobic pathway,

以及不倚靠氧氣的方法，或「厭氧」途徑

which is also called fermentation.

後者也稱為發酵（fermentation）

When you bake bread, yeast can use both pathways,

當烤麵包時，酵母能使用這兩種途徑

but they normally prefer to start with the anaerobic process of fermentation.

但是通常會從厭氧途徑發酵開始

In this process, ethanol is produced in addition to CO2.

在這個過程，除了二氧化碳以外 還會產生出乙醇（酒精）

No, bread isn't alcoholic.

不對，麵包沒有酒精

Small amounts of alcohol that are secreted evaporate during baking.

因為少量的酒精 在烘烤時就悄悄地蒸發了

In the aerobic, or oxygen-dependent pathway,

在有氧，或是依靠氧氣的途徑

the yeast consume some of the sugar

酵母消耗部份的糖

and produce carbon dioxide gas, or CO2, and water.

產生出碳酸氣，或二氧化碳和水

In both processes, the CO2 accumulates and creates tiny bubbles.

這兩種過程中 二氧化碳都會積聚產生小泡泡

These bubbles get trapped by gluten and create a sponge-like structure

這些氣泡就會被麵糰封包 產生海綿狀結構

that gives the bread its soft texture.

使麵包變得質地鬆軟

Wine also relies on yeast.

葡萄酒也需要酵母

But a wine-making set-up keeps the oxygen levels low

但是釀酒的裝置維持在低氧狀態

so that yeast consume sugar using fermentation,

導致酵母消耗糖分進行發酵

the anaerobic pathway.

採用厭氧途徑

The process often starts with wild yeasts already hanging out on the grapes.

這過程一開始是用 早已存在葡萄外皮的野生酵母

But to get consistent results,

但是為了使品質一致

most winemakers also add carefully selected strains of yeast

大部分釀酒師也會添加 精心挑選的酵母菌種

that can tolerate high levels of alcohol.

能夠承受高酒精度的酵母

The yeast consume the sugar in the grape juice,

酵母消耗葡萄汁中的糖分

and as the sugar level drops,

隨著糖分降低

the alcohol level rises.

酒精度就升高

This doesn't necessarily mean that sweeter wines have less alcohol.

這未必就意謂著 較甜的酒其酒精度就較低

Different types of grapes start with different amounts of sugar,

不同品種的葡萄原本就有不同含糖量

and sugar can also be added.

而且糖也能夠額外添加

What happens to the carbon dioxide?

那麼二氧化碳呢？

It just bubbles away through a vent.

二氧化碳會從排氣口排出

In carbonated alcoholic beverages, like champagne and beer,

在碳酸酒精飲料中，像是香檳或啤酒

sealed containers are used in primary or secondary fermentation

在首次和二次發酵會使用密閉容器

to keep the carbon dioxide in the bottle.

以保留二氧化碳在容器內

Wine also introduces us to our second type of food-producing microorganism:

葡萄酒也讓我們認識 第二種製作食物的微生物：

bacteria.

細菌

A special strain of bacteria

一種特殊菌種

turns a tart compound in grape juice into softer tasting ones

將葡萄汁液中的酸性物質 變得口感溫和

that are responsible for some of the flavors in red wines and chardonnays.

這就是紅酒及霞多麗白酒 主要的風味來源

Another type of bacteria, called acetic acid bacteria,

另一種細菌稱為「醋酸菌」

isn't so desirable in wine,

在酒中並不討喜

but they have their function, too.

但是它仍然有功用

If there's oxygen around,

如果環境中有氧氣

these bacteria convert the ethanol in wine into, well, acetic acid.

這個細菌會轉化酒中的 乙醇（酒精）變成乙酸（醋酸）

Let this process continue and you'll eventually get vinegar.

讓這過程持續最終得到的就是醋

Bacteria are the key for cheese, too.

細菌對於起司也是關鍵要素

To make cheese, milk is inoculated with bacteria.

要製作起司，牛奶要注入細菌

The bacteria gobble up the lactose, a kind of sugar,

細菌會消耗掉所有的乳糖，一種糖分

and produce lactic acid, along with many other chemicals.

產生乳酸，和許多其他化學物質

As the milk gets more and more acidic,

隨著牛奶越來越酸

its proteins start to aggregate and curdle.

蛋白質會開始聚集和凝固

That's why spoiled milk is clumpy.

這就是為什麼變質的牛奶會結塊

Cheesemakers usually add an enzyme called rennet,

起司製造者通常 加入一種酶，稱作凝乳酶

naturally found inside of cows, goats, and some other mammals

- 原來存在於 牛、羊或一些哺乳動物體內 -

to help this process along.

幫助這個過程的進行

Eventually, those little curdles turn into bigger curds,

最後，這些小凝塊會凝結成大凝塊

which are pressed to squeeze out the water,

然後把水分壓出來

and create a firm cheese.

製作成紮實的起司

Different strains of bacteria make different kinds of cheese.

不同品種的細菌製作不同的起司

For example, a species of bacteria that emits carbon dioxide

舉例來說，一種會釋放二氧化碳的菌種

is what gives swiss cheese its characteristic holes.

使瑞士起司產生特有的孔洞

Some cheeses, brie and camembert, use another kind of microorganism, too:

有些起司，布里乾酪和卡門貝爾 也使用其他種的微生物：

mold.

霉菌

So your kitchen functions as a sort of biotechnology lab

所以你的廚房就像是一種生物實驗室

manned by microorganisms that culture your cuisine.

由微生物培養出美味食物

Yogurt, soy sauce, sour cream, sauerkraut,

優格、醬油、酸奶油、酸菜

kefir, kimchi, kombucha, cheddar, challah, pita, and naan.

克菲爾、韓式泡菜、康普茶、巧達起司、 哈拉麵包、皮塔餅和印度烤餅

But maybe not all at the same dinner.

但可能不會在一餐內同時享用吧！