11Apr 2018 by Vincent Summers 4 Comments

Cooking Onions: Flavor Chemistry Changes

Chemistry, Food
[caption id="attachment_21597" align="alignright" width="480"] M-m-m, Sweet![/caption] An onion, particularly a yellow or Bermuda onion possesses a strong, perhaps acrid flavor. And its aroma? You are likely to weep when you chop one! Yet, if you take that same onion and fry it, it can be just as fragrant and sweet as ever you could wish. What happened? It's a matter of chemistry. From Wild to Tame The flavor of a raw onion is the product of a number of complex organic substances. The ingredient primarily responsible for tear-ing, is (Z)-propanethial-S-oxide. This compound, a lachrymator (tear-producing gas), is produced when onion cell walls are broken by slicing and chopping. Does frying result in a decrease of this chemical, resulting in sweetness? Does this compound decompose on frying to producing the sweetness?1…
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22Mar 2014 by Vincent Summers 1 Comment

Chopping Onions Makes You Cry

Chemistry, Food
[caption id="attachment_17235" align="alignright" width="480"] Purple onion.[/caption] You are about to prepare a delicious meal—a meal that requires you to slice or chop onions. Do you dread the task?  The act of chopping onions is simple enough, but you know already chopping onions makes you cry. Why? What can you do to avoid it? Let's find out. Chopping Onions Makes You Cry The chemical that comes from preparing onions is called a lachrymator. That word lachrymator is simply defined as a chemical that irritates the eyes, causing tears to flow. In fact, a purely gaseous lachrymator may be called "tear-gas." Yes, onions produce tear-gas: specifically, (Z)-propanethial-S-oxide (PTSO). Onions of themselves don’t cause a problem. It is the slicing and chopping of them, the damage inflicted to the cell walls, that causes…
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