How does 1. cornmeal, 2. but not salt, help whiten clam meat?
Aliza Green's The Fishmonger's Apprentice : The Expert's Guide to Selecting, Preparing, and Cooking a World of Seafood, Taught by the Masters. p 142.
To begin, place the clams in a sink or large pot of cold saltwater (use 1/2 cup [150 g] salt to 1 gallon [3.8 liters] of water). Add 1/2 cup (70 g) cornmeal to help whiten the meat if desired. Leave the clams to purge for 30 minutes to 1 hour. Scoop the clams from the water, leaving the sand and grit behind. Have ready a clam opening knife (see "A Few Good Tools"). It is highly rec- ommended that you wear a protective glove on your nonwriting hand.
Because you are instructed to purge the clams in salt first, this book implies that salt can't help whiten the clam meat. Why can corn meal, but not salt?