Does Searing Meat Seal in the Juices?

Where the idea came from

The rule has a famous author. In 1847 Justus von Liebig, one of the leading chemists of his day, argued that the juices in meat held much of its nourishment, and that hitting meat with high heat at the start would form a crust that kept them inside.

It sounded scientific, and cooks ran with it. The French chef Auguste Escoffier repeated it in the early 1900s, and American cookbooks carried it for decades. The theory had a second problem too: the water-soluble substances Liebig worried about turned out to matter very little nutritionally.

What the tests found

The idea was put to the test early. A 1930 University of Missouri study found that roasts cooked at a steady temperature lost less liquid than roasts seared first. Belle Lowe, who taught experimental cookery at Iowa State, was telling home cooks in 1934 that unseared roasts stayed just as moist.

Modern test kitchens keep getting the same answer. America's Test Kitchen cooked eight rib-eyes to 125°F, searing half before they went in the oven and half after. Both batches lost about 22 percent of their weight as liquid.

The crust simply is not waterproof. Listen to a steak in a hot pan: that steady sizzle is water reaching the surface and boiling off, the whole time it cooks.

So why sear at all? Flavor

Browning is the point. When the surface of meat dries out and gets hot, amino acids from proteins react with sugars and form a large family of new compounds that taste roasted and savory and turn the surface brown. It is called the Maillard reaction, after the French chemist Louis-Camille Maillard, who described it in the 1910s.

Water slows that reaction down, which is why boiled meat never browns. It is also why our smash burger goes into a dry, very hot pan and gets pressed flat: more contact with the steel, more crust. Our Sonora-style carne asada does the same thing over a fire, with thin steaks that brown hard in the few minutes they need.

Searing first or last is your call, since the juice loss comes out about the same. Our Japanese hambagu sears the patties first, then steams them gently in red wine and uses the browned bits in the pan for the sauce.

What actually keeps meat juicy

Doneness matters most. The further meat is cooked, the more its proteins squeeze out water, so a thermometer does more for juiciness than any searing order.

Salt helps if it has time. America's Test Kitchen explains that salting ahead lets the salt work into the meat and change its proteins so they hold on to more of their own juice.

Resting helps too. In America's Test Kitchen's pork loin test, roasts sliced right away lost about 10 tablespoons of juice, while roasts rested 10 minutes lost about 4.

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