The Book of Household Management by Mrs. Beeton

most effectually preserves its nutritive qualities. Meat is roasted by being exposed to the direct influence of the fire. This is done by placing the meat before an open grate, and keeping it in motion to prevent the scorching on any particular part. When meat is properly roasted, the outer layer of its albumen is coagulated, and thus presents a barrier to the exit of the juice. In roasting meat, the heat must be strongest at first, and it should then be much reduced. To have a good juicy roast, therefore, the fire must be red and vigorous at the very commencement of the operation. In the most careful roasting, some of the juice is squeezed out of the meat: this evaporates on the surface of the meat, and gives it a dark brown colour, a rich lustre, and a strong aromatic taste. Besides these effects on the albumen and the expelled juice, roasting converts the cellular tissue of the meat into gelatine, and melts the fat out of the fat-cells.