This old saw has been around for ages, partly because meat cooked over low heat will leak liquid while meat cooked over high heat—seared—appears not to. The high heat, it is claimed, forms a waterproof skin on the meat, so the liquid stays in the meat and the meat turns out jucier. But that’s not what is happening.
When you cook meat, the collagen fibers in the flesh contract and squeeze liquid out of the meat regardless of the cooking temperature. With high heat, the liquid boils away immediately and you never see it, while at lower temperatures the liquid accumulates in the pan. The sizzle you hear over high heat is in fact the sound of that liquid rapidly boiling away.
Searing is important for another reason, specifically the Maillard reaction. When the proteins and sugars in meat are exposed to high heat, a host of chemical reactions take place, and lots of new flavor elements are created. It is these flavors, both in the browned surface of the meat and in any pan juices that result, that make seared meat taste and smell special.
Another reason for this myth may be because searing meat that will be stewed, roasted, etc. does indeed give tastier results. It has nothing to do with sealing in the juices, however. Careful experiments took identical pieces of meat and cooked them with and without searing. If searing did seal in juices, then the seared meat would lose a smaller percentage of its weight during cooking than the unseared piece and thus be heavier after cooking. In actuality, both the seared and unseared meat lost about the same amount of weight.
And some more info about cooking meat is here.
It seems to be a common belief that once frozen meat has been thawed, freezing it again is unsafe. This is false. There may be some loss of quality and texture, but the refrozen meat will be perfectly safe. This is of course assuming you always follow the usual precautions regarding meat while the meat is thawed.
This seems to make sense—cooking meat in a moist environment would keep it moist, right? Not necessarily. A major determinant of the final moistness of meat is how hot it got during cooking. So, how you stew or braise the meat is really important. Cook at a boil, where the meat may reach over 200 degrees, and it’s likely to be dry. Cook at a gentle simmer, keeping things at 180 degrees or so, and the results will be much better.
Sorry, it just ain’t so. I say “sorry” because there are some people who seem to want grilled meat to be unhealthy—beats me as to why (perhaps it’s the “if it tastes good it must be bad for you” syndrome?). Anyway, this myth got its start because grilling—like some other cooking techniques—produces heterocyclic amines (HCAs), which are “reasonably anticipated” to be carcinogens in humans. What this means is that there is no evidence that they actually are carcinogens in humans, but someone thinks that if they keep looking long and hard enough they will find some evidence. As an example, a recent prospective study in 120,000 women found no relationship between breast cancer and eating red meat or the way the meat was cooked. “But but but,” the worry-warts will say, “HCAs cause cancer in rats and mice!” Yes, but we are not rats or mice (most of us, anyway) and what’s true for them is not always true for us. There is evidence, for example, that early humans adapted a digestive system to safely eat cooked food while rodents did not. Also, just because a high dose of something, like the high doses of HCAs that the experimental rats and mice were given, causes a health problem does not mean that the very small doses we get in our food will also cause a problem.
