A chemical reaction converts the sugar in the corn into starch - and the longer the corn is off the stalk, the greater the conversion. Corn connoisseurs can detect the drop in sweetness within an hour after harvesting, which explains the rationale for this seemingly snobbish recipe: Don't pick the corn until a pot of water, not more than a minute's run from the cornfield, is boiling.
Heat also affects the conversion process. The higher the temperature of the ear, the faster the chemical reaction occurs. For this reason, unless you intend to cook the corn immediately, refrigerate it as soon as it enters your kitchen.
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