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第一段
1 .In today's lecture, I'm going to talk about Monosodium Glutamate，or MSG, as it's more commonly known.
在今天的演讲中，我会谈论味精，或者说是MSG，因为它更广为人知。
2 .Now, MSG, as you probably know, is a flavour enhancer which is used particularly in Chinese and Japanese cooking.
现在，你可能知道，味精是一种味道增强剂，尤其是在中国和日本的烹饪中使用。
3 .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?
今天我要探讨为什么它在这些美食中是如此受欢迎，更重要的是，它是如何提高食品的风味的?
第二段
1 .The main reason why MSG is more commonly used in Japanese meals is tradition.
味精在日本的饮食中更常用的主要原因是传统因素。
2 .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.
几千年以前，日本已经开始烹饪一种昆布海藻，因为他们发现它有使食物味道更好的能力。
3 .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，科学家发现海藻能使食物风味变好的成分，谷氨酸。
第三段
1 .From 1908 until 1956, glutamate was produced commercially in Japan by a very slow and expensive means of extraction.
从1908年至1956年，谷氨酸在日本以非常缓慢和昂贵的手段提取生产。
2 .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年速度得到了改善，工业生产大幅增加。
3 .In fact, hundreds of thousands of tonnes of MSG are produced all over the world today.
事实上，世界上现在已经生产了成千上万吨味精。
第一段
1 .So what exactly is MSG?
那么什么是味精?
2 .Well, Monosodium Glutamate contains seventy-eight point two per cent glutamate, twelve point two per cent sodium and nine point six per cent water.
嗯，味精含有87。22％的谷氨酸，12．2％的钠和9．6％的水。
3 .Glutamate is an amino acid that can be found naturally in all protein-containing foods,
谷氨酸是一种氨基酸，可以在自然的合有蛋白质的食品中找到，
4 .erm, so this includes food such as meat and cheese.
呃，这包括如肉类和奶酪等食品。
第二段
1 .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.
众所周知，中国和日本的食品合有味精，但许多人似乎不知道，它也被用于在世界其他地区的食品制作。
2 .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.
例如在商业上，意大利的比萨饼，美国快餐，英国用于像薯片等。
第三段
1 .So, how exactly does MSG work?
那么，味精是如何起作用的呢?
2 .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.
嗯，在西方世界，我们通常谈论四种口味，而且肯定你们都熟悉的概念，甜，酸，苦和盐。
3 .Well, in 1908, Kikunae Ikeda identified a fifth 'taste'.
嗯，1908年，池田菊苗确定义了第五种“味道”。
4 .And it is thought that MSG intensifies this naturally occurring taste in some food.
而且它被认为，味精在一些食物中会增强这种自然发生的‘味道’。
5 .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.
它确实有一个完美的进化意义，我们应该有能力来检测或品尝谷氨酸，因为它是最常见的天然食品中的氨基酸。
第四段
1 .John Prescott, an associate professor at the University of Chicago, suggests that this fifth taste serves a purpose just as the other tastes do.
芝加哥大学的副教授普雷斯科特建议，这第五个口味有存在的意义，正如其他口味一样。
2 .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.
它把食物中存在蛋白质的信号传递给我们，就像甜味以同样的方式表明食物中合有能量和碳水化合物。
3 .Bitterness, he says, alerts us of toxins in the food, while sourness warns us of spoilage and saltiness signals the presence of minerals.
苦，他说，提醒我们食物中的毒素，而酸味和咸味信号警告我们的变质的矿物的存在。
第五段
1 .So, what else do we know about this fifth taste...
所以，我们还知道这第五种味…