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…
Read More

What Gives Boiled Eggs Sulfur Smell? Is Sulfur Bad for You?

Food, Health
[caption id="attachment_15992" align="alignright" width="440"] Hardboiling eggs.[/caption] Peel a boiled egg, break it open, and you will detect the distinct boiled eggs sulfur smell. Now foods do not contain sulfur (symbol S) in its elemental form. Rather, they contain compounds that include sulfur in their composition. What sulfur-containing compounds do we find in hen's fruit? In themselves, they are nutritious—even essential—compounds. Boiled Eggs Sulfur Smell: Amino Acids Eggs contain proteins such as albumin. Proteins are amino acids that have joined together. Amino acids are nutritious chemicals that contain nitrogen. Most amino acids do not contain sulfur. However, two do contain sulfur in addition to nitrogen—methionine and cysteine. In fact, they contain nitrogen and sulfur in equal amounts. The chemical formula of methionine is C5H11NO2S. Cysteine is C3H7NO2S. Boiled Eggs Sulfur Smell:…
Read More

What are Allotropes?

[caption id="attachment_6012" align="alignright" width="440"] Cyclooctasulfur (S8)[/caption] What are allotropes? An allotrope is one of a variety of forms in which an element can exist. This does not refer to the state of an element, whether solid, liquid, gas, or plasma. It refers to the tendency of an element to exist in different structural forms. Allotropes of Carbon Thus carbon can be found in a variety of forms, including graphite, charcoal, diamond, fullerenes, and nanotubes. Of Sulfur Sulfur allotropes take an assortment of forms. These include rings that range from six to twenty atoms. Especially well known are the monoclinic and rhombic crystalline forms. Of Phosphorous Phosphorus allotropes exist in a variety of colors. Ordinary phosphorous is called white phosphorous (P₄). It is unstable and dangerous. But there are also red,…
Read More