Removing Scum from Meat

Meat or bones that you've just bought tends to have blood in it, and random other proteins that will come out in the cooking process. If you cook that meat in water, for example, in a soup, the blood and proteins will get drawn out, and form this black-ish foam on top of the soup.

The scum is perfectly edible, it's just cooked proteins. However, its appearance is not very appetizing, it could get burned when cooking on a stovetop, it clouds up the soup broth, and it affects the texture and flavor of the soup. But, depending how much you care about each of these things, it may or may not be worthwhile to apply some or all of the following techniques. Use your feelings to decide.

So, here's some ways to help remove the scum. Do I do all of these things? Definitely not. I don't care that much about how it changes the texture or flavor of the soup, or how cloudy the soup broth is. And I definitely don't care enough in proportion to the work I need to put in to avoid those things. But maybe my guests care... Sorry guests.

Soaking

Soaking the meat or bones in water, for 30 minutes up to 1 hour, will help draw out some of the blood and other proteins. You could try soaking it for even longer, like 3+ hours, but that seems kind of gross, requires a lot of foresight, and it's unclear how much more blood you can remove as compared to soaking for 1 hour.

Do I use this technique?

Usually, yea. It doesn't require a whole lot of work, and it can be done in the same bowl or pot that I want to cook the meat in, so no extra dishes either.

Parboiling

Boil some water, dump the meat in, let the water boil again, and cook the meat just enough so that the outside is set. Or you could just dump the meat in cold water, and let the water boil a bit to cook the meat. What's the difference? I don't know, maybe the meat will be a little more cooked in the later case, so you're losing some flavor to this water that's going to be unused.

Anyway, this should draw out most of the blood and scum from the meat. Then you can rinse the scum off the meat in a colander, and rinse the scum out of the pot as well. Plus, now that the meat is a little more cooked, less scum should come out of the meat as you proceed with the rest of the cooking.

Do I use this technique?

Usually, no. It's more dishes to wash. And if I'm making soup, which is usually the only case where I would even consider removing scum from meat, I need to wait for the water to boil twice: once to parboil, and again to make the soup. Ain't nobody got time for that. We're busy people here, I'm cooking homemade meals, not meals for a restaurant.

Skimming

Probably the most effective way to ensure that all the scum is removed, is to stand diligent watch, and skim off any scum that floats to the surface as the soup is simmering away. This is best done in conjunction with parboiling, because very often, there will be some scum stuck to the meat as it's cooking. Scum that's stuck to the meat is easily rinsable in the parboiling step, but you can't really remove in the skimming step. Otherwise, keep simmering and skimming until there's no visible scum left, and your resulting soup broth should be nice and clear!

Do I use this technique?

Heck nah. I'm not gonna stand watch over a soup for half an hour to skim away the scum. I could be cooking something else, or doing something else while the soup is being made.