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In today's lecture, I'm going to talk about Monosodium Glutamate, or MSG, as it's more commonly known.

在今天的讲座里我要来讲一讲谷氨酸钠，也就是我们常说的味精。

Now, MSG as you probably know, is a flavour enhancer which is used particularly in Chinese and Japanese cooking.

你大概知道味精是一种在中国和日本饮食中常用的增味剂。

Today I am going to explore why it is so popular in these cuisines and, more importantly, how does it enhance the flavour of food?

今天我们就来探讨一下它为什么在这些饮食文化中这么盛行，以及更重要的是它如何给食物增味。

The main reason why MSG is more commonly used in Japanese meals is tradition.

味精在日本广泛使用的主要原因是饮食传统。

For many thousands of years the Japanese have incorporated a type of seaweed known as kombu in their cooking, as they discovered it had the ability to make food taste better.

数千年来日本人在烹饪时一直用一种叫昆布的海藻，因为日本人发现昆布会让食物的味道变得更加鲜美。

But it wasn't until 1908 that the ingredient in kombu which was responsible for the improvement in flavour was actually discovered to be glutamate by scientists working there.

但直到1908年在日本工作的科学家才发现昆布中让食物变得更美味的成分是谷氨酸。

From 1908 until 1956, glutamate was produced commercially in Japan by a very slow and expensive means of extraction.

从1908年到1956年，谷氨酸以一种十分低效且昂贵的提取方式被商业生产。

It was in 1956 that the speed of the process was improved, and industrial production increased dramatically and still continues to increase to this day.

在1956年谷氨酸的生产速度有了很大的提高，其工业生产量也飞速上涨，到今天仍增势不减。

In fact, hundreds of thousands of tonnes of MSG are produced all over the world today.

实际上，每一天全世界都有数以万吨的味精被生产出来。

So what exactly is MSG?

那味精到底是什么呢？

Well, Monosodium Glutamate contains seventy-eight point two per cent glutamate, twelve point two per cent sodium and nine point six per cent water.

谷氨酸钠的成分包含78.2%的谷氨酸，12.2%的钠和9.6%的水。

Glutamate is an amino acid that can be found naturally in all protein-containing foods, erm, so this includes food such as meat and cheese.

谷氨酸是一种氨基酸，天然存在于所有的含蛋白质的食物中，比如肉类和奶酪。

It is widely known that Chinese and Japanese food contains MSG but many people don't seem to be aware that it is also used in foods in other parts of the world.

大家都知道中国和日本的食物含有味精，但很多人不知道的是它在世界上很多其他地方也被使用。

For example it is found in commercially made Italian pizzas, in American fast food and in Britain MSG is used in things like potato crisps.

例如，市面上的意大利披萨、美国的快餐，还有英国的一些食物比如薯片中都添加了味精。

So, how exactly does MSG work?

那么味精是如何让食物变得美味的呢？

Well, in the Western world, we commonly talk of four 'tastes', and I'm sure you're all familiar with the concepts of sweet, sour, bitter and salt.

在西方世界里，我们一般只谈论四种味道：甜、酸、苦和咸。这个你们应该都很熟悉。

Well, in 1908, Kikunae Ikeda identified a fifth 'taste'.

在1908年Kikunae Ikeda发现了第五种味道。

And it is thought that MSG intensifies this naturally occurring 'taste' in some food.

人们认为味精能够在某些食物中强化这种在自然界存在的味道。

It does make perfect evolutionary sense that we should have the ability to detect or taste glutamate because it is the amino acid which is most common in natural foods.

从进化的意义上来说我们应该能够鉴别出谷氨酸的味道，因为它是一种在天然食物中广泛存在的氨基酸。

John Prescott, an associate professor at the University of Chicago, suggests that this fifth taste serves a purpose just as the other tastes do.

约翰·普利斯科特是芝加哥大学的一名副教授，他认为这第五种味道和其他四种一样，具有一定的作用。

He suggests that it signals to us the presence of protein in food, in the same way that sweetness indicates that a food contains energy-giving carbohydrates.

他认为这种味道能够提示我们食物中蛋白质的存在，就像甜味能够告诉我们食物中含有能提供能量的碳水化合物一样。

Bitterness, he says, alerts us of toxins in the food, while sourness warns us of spoilage and saltiness signals the presence of minerals.

而苦味则提醒我们食物中潜在的毒素，酸味是食物变质的警告，而咸味则是矿物质存在的信号。

So, what else do we know about this fifth taste…

那么，关于这第五种味道我们还知道些什么呢……