Question asked by a foodie friend:
- Recently I made some dishes that included sauteed onions. Now I’ve been doing sauteed onions, etc. since I started cooking for myself sophmore year in college. Let’s just say this was during the Ford administration.
What I am wondering is if anyone knows the difference from a chem/food science/taste standpoint of sauteeing different types of onions.
For example I had a big red onion laying around last time. The resulting carmelization was quite dark as a result. However it was not quite as distinctly carmelized tasting as the last batch I made (which were probably some type of sweet onions). It tasted good, just different. Can that be the result of the color? Something else?
Do the different types have any real taste difference other than that which would result from varying sugar content?
In addition to varying degrees of sugars, onions vary in their levels of sulfur compunds, amino acids and water.
From McGee’s “On Food and Cooking”, p311:
- “When onions and their relatives are heated, the various sulfur compounds react with each other and with other substances to produce a range of characteristic flavor molecules. The cooking method, temperature, and medium strongly affect the flavor balance.”
Comparing the nutritional info for red onions vs different types of onions would be interesting. Unfortunately the usda database doesn’t have an entry for reds.
My limited understanding is that anthocyanins mainly contribute color to the red onion vs altering its flavor profile.
When sauteeing onions and pushing them beyond we’re bringing the Maillard reaction into play with the sugar-carbohydrate-amino acid compounds of an onion.
- “Maillard flavors are more complex and meaty than caramelized flavors, because the involvement of the amino acids adds nitrogen and sulfur atoms to the mix of carbon, hydrogen, and oxygen, and produces new families of molecules and new aromatic dimensions” McGee, p778.
The accompanying diagram in the quoted text further shows how compounds beyond sugars lend themselves to the complex flavors of a Maillard reaction. The contributing sulfur compounds and amino acids produce more ‘ring’ structures, aka aromatics, than caramelization produces.
So, in addition to varying amounts of sugars, the various levels of sulfur molecules and differences in amounts of amino acids contribute to different flavors in different types of onions.
(I think we could also pull the concept of Terroir out from winemaking into the world of onion flavors, esp when talking about the low sulfur Sweet onions.)
ps usda info on
1. raw welsh onions (Allium fistulosum)
2. raw onion (Allium cepa)
3. sweet raw onion
4. yellow onion sauteed
