The endosperm is mostly made up of sugar. When the ear is picked, it senses that something is seriously wrong and it deploys an enzyme that starts rapidly converting the sugar to a more easily metabolized starch. A culinary time bomb.
How fast does this happen? Well, let me put it this way. I know corn connoisseurs out there who actually put a pot of water on to boil before they go down to their market for their corn.
You can buy yourself some time by only choosing really fresh corn. When you pick up an ear take a really good look at it.
- Is it plump?
- Is the husk bright and moist?
- Is the cut end bright and moist?
There shouldn't be any dark splotches there.
- Look at the tassel. The tassel should be slightly sticky and brown — not matted and black. A black tassel signifies a mature ear with more starch than sugar.
- Take a look inside.
- The kernels should be tight, rowed all the way up to the top, and should explode with milky goodness when pierced.
You can get maybe 1-3 days out of your fresh corn if you
wrap it tightly in plastic and put it in the coldest part of your freezer.
If you're looking for
even more time, you're going to have to take a cue from food scientists at the University of Maryland who've actually figured out that you can hold corn at it's peak of flavor
for up to two weeks if you shuck it and give it
a 15 minute bath in ice water that has been laced with one drop of lemon juice and -- believe it or not — two drops of
Clorox bleach. It turns out that the bleach/citrus Mickey lowers the water's pH just enough to inhibit both microbial and enzymatic action in the corn.
If your corn has been stored for more than a day or two, or if the farm is more than two zip codes down the road, add two tablespoons of sugar to the bath — but no salt.
Post bath, just seal it up in a freezer bag and put it right back into the coldest part of your refrigerator.