The Chemistry of Smell

Rui M.

Life in NYC is not easy. One of the biggest problems is the food. Of course, I can eat out a few times since the city is filled with wonderful restaurants. But as living becomes more and more expensive, I have to force myself to eat at home. Cooking is a real challenge, especially since my spice tolerance is terribly low; I can’t eat food with a strong smell (I think this is a good explanation for why I’m a cheese and garlic hater, but people still think of me as a “weirdo”). My oldest and probably only friend, D, never understood my own personal preferences about food. After she cooked for me this afternoon, my whole apartment ended up with some interesting smells – the smell of garlic and camembert. Of course I know she did it on purpose!

Why do camembert and garlic have such mysterious smells? I found a blog that gave me the perfect answer to my question, although it was sometimes so academic that I couldn’t understand a word. The blogger suggested that camembert has such a strong smell because of the wide range of compounds that are produced during the ripening process. The chemicals with scary names include dactyl, which makes the cheese buttery, methanol, which gives the cheese the smell of boiled potatoes, methanethiol (the smell of cabbage), and 1-octen-3-one (the smell of mushrooms). I guess I can stand the smell of each chemical in isolation, but after they are mixed up, all I want to do is stay as far away as I can.

However, that’s not the whole story about camembert.  There is another compound that makes it even more unbearable: ammonia. This compound is produced by the deamination of amino acids and its amount increases as the camembert becomes ripe. So as time passes, the smell may become unexpectedly strong and then no one can bear it–not only me.

Similar to camembert, garlic has its own chemical contributors that lead to its unique smell, including diallyl disulfide, allyl methyl sulfide, allyl mercaptan, and methyl disulfide. These compounds are absorbed and passed into the bloodstream, and then passed on to other organs. The compounds travel through the body and are eventually excreted though the skin and breath. These compounds are what cause  “garlic breath”. Allicin, on the other hand, is a chemical that is responsible for the smell of chopped garlic. This compound is formed when the garlic clove is damaged and the enzymes break down alliin, which eventually becomes allicin.

Although I hate the smell of garlic, I understand that many people love it. So I have  good news for people who love garlic dishes but worry about garlic breath: there are plenty of foods that can reduce garlic breath. For example, milk, apples, parsley, and mint can all help. However, the mechanism behind this reduction still remains unclear. Some researchers think that chlorophyll, which is usually found in vegetables, is the main contributor to this reduction effect. Other researchers do not agree with this hypothesis. They suggest that an enzymatic action is the main reason, since enzymes break down most of the organosulfur compounds. Hope our future chemists can solve this problem one day.

Obviously, the smell of camembert and garlic, no matter whether I like it or not, is all about chemistry! So choosing food is like choosing the correct chemicals:  each individual has his or her own preference. Some people prefer the strong smell of onions while others prefer the faint aroma of apples. Chemicals are the contributors! Chemistry is found everywhere in the world, but most people simply ignore it (OK, I have to admit that I’m one of them). After I read the chemist’s blog, I was attracted to this study of compounds. I decided to apply to a college and study chemistry from now on. Fantastic decision, right?

Friends, it’s time for dinner. D is mad at me right now. Hopefully, I’ll post more interesting facts about chemistry later. See you next week!

References:

The Chemistry of Camembert

What Compounds Cause Garlic Breath? – The Chemistry of Garlic

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