Post #307053 by The Gnomon on Thu, May 17, 2007 12:46 PM

Digi, in your case, I wouldn't be surprised if you had just run into Persian limes from two different farm sources, the smaller ones having experienced a bad growing season. They could also be Persians and another variety of lime that isn't Key lime (e.g., Kaffir limes—very bitter, bumpy-skinned, look like little spherical green brains: but their leaves are essential in Thai cooking).

I'm just guessing now, even though I should probably know (and most likely will find out soon), but I suspect that most of the limes we buy in the grocery stores are of a grade called "US Combination." The USDA grades for limes are: US No. 1, US Combination, and US No. 2. Because limes don't "have" to be graded, there is also the designation, "unclassified."

Since there always seems to be a mixture of lime qualities in each carton of limes that is received into the grocery stores, it's probably US Combination. I would think that US Combination would be cheaper for the stores to get than something requiring more labor to distinguish quality.

Here is the USDA specification for the grades of Persian (Tahiti) limes.

Plump, soft, heavy limes, regardless of other characteristics, are going to be juicy. The shiny, smooth-skinned ones taste the best. Bigger is not better. I'd rather have a smaller lime of excellent quality than a "green lemon" of twice its size.