Size
Forget labels like “medium,” “large,” or “jumbo”:
these are unregulated terms that are decided on by
the packager or the supermarket. Instead, look for a
set of two numbers, such as 26–30 or 16–20. These
numbers indicate the number of individual shrimp
that it takes up to make a pound. So a package
labeled 16–20 will contain shrimp that weigh in at a
little less than an ounce each. The smaller the
number, the larger the shrimp. For superlarge
shrimp, you may see a number like U–15, which
means that it takes under 15 pieces to make up a
pound. As far as flavor goes, there’s not much
difference among the sizes—look to individual
recipes to specify the right size of shrimp for the job.
Additional Ingredients
Shrimp, like scallops, are often treated with STP
(sodium tripolyphosphate), a chemical intended to
help them retain moisture. More than anything, this
is a ploy to bulk up their weight and sell them at a
higher profit. Check the ingredients list on packages
of frozen shrimp. They should list shrimp, possibly
salt, and nothing else.