I'm a huge fan of avocados. Though I often forget this fact, when I do manage to remember, I find myself gorging on their subtle sweet slimy goodness as often as possible. My favorite sandwich in the whole world is fresh turkey with a good hunk of crunchy lettuce, a thin slice of fontina and half of an avocado sliced and laid out. The problem is, I don't often eat more than half an avocado (some fats are good, I know, but they're still fats) and my husband can't stand them, even after my repeated insistings on guacamole taste-testing (poor guy).
Anyway, last night we had some truly delicious and simple microwave nachos for dinner. It's hard to bring one's self to cook anything when the heat is as bad as it's been here in Michigan. I made my nachos with some corn, pickled jalepenos, tomatillo salsa, cheese, black beans and topped it off with a beautiful half avocado (I love California's summer fruits, even if they have to travel a long way to get here!) and found myself staring blankly at the other half. What was going to happen to it? So often I waste the "other half" simply because it goes brown and mushy within a few hours of being cut open... I'm picky, I admit, and won't eat a brown mushy avocado.
So I stood there staring at the half avocado and then at the shell of the half avocado skin. It suddenly occurred to me that if the avocado wasn't exposed to anything other than itself it might (for lack of better words) think that it was still whole. Okay, I know this is a totally silly notion, but ah well, I tried it. I took the shell of the skin and set it over the avocado to make it look like it was whole again and left it on the kitchen counter for the night.
This morning I went to check on it more than twelve hours later and Lo and Behold when I pulled off the empty half the other side was green and as fresh-looking as it had been the night before! I could remember some vague concepts from science about the ripening of fruit and oxidation speeding along various enzymes... or something... It's been a while. That's where my thought came from and I'm glad I was right to try it out!
Okay, I'm a food geek so I'll be the dorky one and post the food science (which you had mostly correct anyway). :-)
ReplyDeleteMost fruits oxidize (turn brown) on their cut surfaces. The oxidation process requires oxygen (duh), so if you can prevent oxygen from getting at the fruit, you can prevent the oxidation. That's why your method works. I'm surprised it worked as well as it did since there's quite a bit of exposed air underneath the "lid", but there you go. Something that might work even better is to wrap it in plastic wrap and make sure the wrap is in direct contact with the cut side of the avocado.
Incidentally, if you've ever wondered how McDonalds manages to serve little packets of cut apples that don't turn brown or why "pre-washed" bagged lettuce and veggies from the supermarket last longer than the fresh stuff, they're using the same principle. I believe the food is chopped mechanically in a low-oxygen environment and packaged in something other than plain air (Nitrogen, most likely). Since there's no air in the bag, the food won't brown till you open it.
You can also chemically shut-down the action by applying an acid (lemon juice or vinegar) to the cut surfaces. It won't work forever, but it's pretty effective for most cooking tasks. That's actually why guacamole stays mostly green--it usually contains citrus juice.
I'll have to try that next time - if there is any Avocado left that is. ;-)
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