The Food Lab: Better Home Cooking Through Science

together and get the loaf to set in a stable form without the
need to overwork the meat. Egg whites have even more
water in them, are devoid of any fat at all, and have a very
mild flavor. Their main role is to add extra loose proteins to
the mix to assist the egg yolks in their quest to add structure
without overworking the meat or adding toughness. We’ll
definitely include them.
Milk and other dairy products, like heavy cream and
buttermilk, contain both water and fat, adding two types of
moisture to our meat loaf. There’s a long-held theory that
milk can tenderize ground meat, and this is the reason often
cited for cooking ground meat in milk to make a Bolognese-
style ragù. I’m pretty skeptical about this. Milk is mainly
water, with some milk fat and a few proteins thrown in.
What could cause it to tenderize meat?
Some sources claim that adding milk limits the cooking
temperature to 212ºF (the temperature at which water boils),
which keeps meat from overcooking. What? Limiting
temperature to 212ºF? What good does that do? Meat
toughens at temperatures a good 70 to 75 degrees below this
threshold. Besides, plain old water (which is abundant in the
meat and all the vegetables you add to meat loaf) will
perform that function just as well. Indeed, cooking three
batches of meat side by side, one simmered in milk, one
simmered in water, and one allowed to simmer in its own
juices, left me with three batches of meat that were equally
tough. Fact of the matter is, milk does not tenderize meat.
The only way to guarantee tender meat is not to overcook it.
And that’s a simple matter of using a thermometer when you
bake the meat loaf.