Brains have long been used in the cuisines of cattle raising peoples, particularly in Europe and to a lesser extent in North America. You'll encounter recipes calling for them in some older American cookbooks, but they still appear in current European cookbooks. This item has almost disappeared in North America and is now very hard to find in markets.
Cooked, brains are grayish and don't look at all appetizing - and that's a very accurate impression. They have a texture similar to tofu but more elastic, and a bland flavor that hints of tongue and liver. Though I like tongue and liver, brains just do it completely wrong. Yuk!
More on Beef Innards
I gather from my recipe books that a "calf brain" weighs about 6 ounces, so that's the amount to use when the recipe calls for "1 calf brain". A full grown cow brain is about 1 pound. The USDA allows harvesting only calf brains.
Buying: Brains can be found sporadically in a very few of the ethnic markets here in Los Angeles. The photo specimen was found at Super King, a large multi-ethnic market (Middle Eastern, Persian, Mexican, Armenian, Russian). It was packed as pieces in a 1 pound tub. Like other organ meats brains are quite perishable and should be cooked soon after purchase.
Substitute: Sweetbreads are considered a superior substitute for brains (well, almost anything would be superior). Another possibility is to just crumble up some extra firm tofu - both the texture and flavor would be much better.
Cooking: Brains are generally given a preliminary cooking in acidulated water (1 T vinegar to 4 cups water) for about 20 minutes and are then cut as required and added to the recipe. Otherwise, do what the recipe asks.
Health & Nutrition: Brains, the beef's and yours, are extremely high in cholesterol. Of course the cholesterol panic is pretty much over since it's now known that most people absorb very little cholesterol from their diets. It's pretty much manufactured within the body, but some people do absorb more from dietary sources and those folks should avoid brains.
The other major problem with brains is the possibility of BSE (Bovine Spongiform Encephalitis - Mad Cow disease). This is believed able to infect humans and is then called New Variant Creutzfeldt-Jakob Disease (vCJD). This disease is caused by a malformed protein which is not destroyed by normal cooking heat, not even "well done", and there is no known treatment. There have been from 1 to 3 deaths in the United States, probably from exposure while living in the UK where the infection of cattle was severe due to unwise feeding practices. I've heard of only one cow found infected in the United States.