No Magic in Pasta Water
Is it a good idea to add a little pasta water to cooked pasta, or should I just add the sauce? Why would it make any difference as long as there is enough moisture ?
Your reasoning is impeccable. Why add water if there is already enough water -- especially since you've just finished draining it?
However, if there should be a substantial delay between draining the pasta and saucing it, it may dry out and stick together. In that case, you'd want to both reheat and re-moisturize so it will mix well with the hot sauce. If you retain all the cooking water by fishing out the pasta rather than by dumping everything into a colander, all you have to do is put the pasta back in the water for a few seconds and it can come out as hot and moist as new. Many restaurants precook and drain their pasta, separate it into individual portions, and then dunk the portions back in boiling water as needed before saucing and serving.
The more usual reason for retaining at least a cup or so of the pasta water is for thinning the sauce in case it's too thick or dry. There's nothing special about this hot water; it's just a handy source of, well, hot water. It's also useful for warming the serving bowls. Of course, if the pasta had been cooked in salted water, adding some of that water to the final dish will certainly kick up its flavor.
But believe it or not, some people claim that you can use a bit of the pasta water to thicken a sauce by adding the water and then simmering the sauce down. After all, the theory goes, the water contains starch dissolved out of the pasta, and starch will thicken a sauce.
"Huh?" I asked myself. "Can there be enough starch in the water to do any significant amount of thickening?" I decided to find out.
I cooked eight ounces of spaghetti in three quarts of water for the six minutes recommended on the package, fished out the spaghetti and boiled the cooking water down all the way to dryness to see how much starch was left. (The final stages of evaporation were done in a dish in a 220-degree oven.) Then I weighed the dried starch.
I found nine grams of starch in the entire three quarts of cooking water. A little calculation showed that, if you were to add a quarter-cup of this water to a pint of sauce in an attempt to thicken it, you would be adding about one-fifteenth of a teaspoon of starch.
That's supposed to thicken it? No way!
We're told not to refreeze food we've thawed because it is unsafe. But how about this "fresh" -- presumably not previously frozen -- chicken I bought? Can I freeze it at home, or must I use it promptly? And if I have a package of frozen vegetables that has partially thawed, can I put it back in the freezer?
There is nothing inherently wrong with refreezing foods. It depends on the food's history before you refreeze it.
The blanket dictum "do not refreeze" is overly cautious. It is based on the worst-case scenario that the food had been thawed by leaving it out on the kitchen counter -- a definite no-no, because bacteria and other microorganisms can thrive at temperatures between refrigerator (40 degrees) and room (70 degrees). And refreezing won't kill them.