Searing Meat gained popularity with a theory originally put forward by Justus von Liebig, a German chemist, in a book he published in 1847.
Von Liebig believed that he had proven that searing meat creates a “crust” on the surface of the meat which would keep juices in. Auguste Escoffier, a French food writer, believed this and wrote of it in 1902. But by the 1930s, owing to funds made available by the US Federal government, Home Economics research was well underway and studies proved the opposite: that roasting meat at a constant temperature actually caused it to lose less fluid than initially seared ones. (University of Missouri study, 1930.) By 1936, Irma Rombauer turned away from searing for the purpose of retaining juices in her “The Joy of Cooking.”
In recent times, though, food writers have forgotten past learning and advocated searing meat to retain juices. Despite this, the science remains that it does not. See “On Food & Cooking: The Science and Lore of the Kitchen” by Harold McGee, Simon & Schuster, 1997, pp 112 – 116.
Why you still want to sear meat sometimes, however, is because the browning does create flavour. When you come across a recipe advising you to sear the meat first to seal in the juices, know that it won’t do any such thing — but sear away anyway, because it does develop taste and visual appeal!
Literature & Lore
“No Need to Sear. It is no longer necessary to suffer the blue fumes and odor of burning grease of the searing dinner roast. Because, contrary to a belief of many year standing, searing does not seal in meat juices, Belle Lowe tells her classes in experimental cookery at Iowa State. Just as moist a product is obtained, she says, when the meat is cooked without the process of searing. ‘Unseared roasts should be cooked uncovered at a temperature of from 300 to 350 degrees F,’ Miss Lowe says. ‘If the temperature goes above 350 degrees the loss of meat juice is too great, and the oven is splattered with grease.'” — For the Homemaker column. Milford, Iowa: The Milford Mail. 25 January 1934. Page 2.
“Searing meat does not seal in juices. Nor does searching reduce the loss of juices. The juiciness of meat is determined by the doneness to which the meat is cooked: the rarer the juicier. Meat marbled with fat will seem moister than a lean cut when cooked well-done; the fat melts and permeates the meat during cooking. Even though searing doesn’t seal in juices, it is a useful technique. A very hot pan will begin cooking the meat right away and will intensify the meat’s flavor by browning the juices that flow from it.” — McGee, Harold. The Curious Cook. New York: Hungry Minds Inc. 1990. The Searing Truth, Part One, Page 21.
Cloake, Felicity. Should you sear steak? Manchester: The Guardian. 26 January 2010.