The Chemistry of Cookery

by W. Mattieu Williams

The high temperature rapidly imparted by radiation to the surface of the meat forms a thin superficial crust of hardened and semi-carbonised albumen and fibre, that resists the outrush of vapour, and produces within a certain degree of high pressure, which probably acts in loosening the fibres. A well-grilled chop or steak is ‘puffed’ out—made thicker in the middle; an ill-cooked, desiccated specimen is shrivelled, collapsed, and thinned by the slow departure or dissociation of its juices.

Happy little couples, living in little houses with only one little servant—or, happier still, with no servant at all—complain of their little joints of meat, which, when roasted, are so dry, as compared with the big succulent joints of larger households. A little reflection on the principles above applied to the grilling of steaks and chops will explain the source of this little difficulty, and show how it may be overcome.

I will here venture upon a little of the mathematics of cookery, as well as its chemistry. While the weight or quantity of material in a joint increases with the cube of its through-measured dimensions, its surface only increases with their square—or, otherwise stated, we do not nearly double or treble the surface of a joint of given form when we double or treble its weight; and vice versâ, the less the weight, the greater the surface in proportion to the weight. This is obvious enough when we consider that we cannot cut a single lump of anything into halves without exposing or creating two fresh surfaces where no surfaces were exposed before. As the evaporation of the juices is, under given conditions, proportionate to the surface exposed, it is evident that this process of converting the inside middle into two outside surfaces must increase the amount of evaporation that occurs in roasting.

What, then, is the remedy for this? It is twofold. First, to seal up the pores of these additional surfaces as completely as possible; and secondly, to diminish to the utmost the time of exposure to the dry air. Logically following up these principles, I arrive at a practical formula which will probably induce certain orthodox cooks to denounce me as a culinary paradoxer. It is this: That the smaller the joint to be roasted, the higher the temperature to which its surface should be exposed. The roasting of a small joint should, in fact, be conducted in nearly the same manner as the grilling of a chop or steak described in my last. The surface should be crusted or browned—burned, if you please—as speedily as possible, in such wise that the juices within shall be held there under high pressure, and only allowed to escape by burst and splutters, rather than by steady evaporation.

The best way of doing this is a problem to be solved by the practical cook. I only expound the principles, and timidly suggest the mode of applying them. In a metallurgical laboratory, where I am most at home, I could roast a small joint beautifully by suspending it inside a large red-hot steel-smelter’s crucible, or, better still, in an apparatus called a ‘muffle,’ which is a fireclay tunnel open in front, and so arranged in a suitable furnace as to be easily made red-hot all round. A small joint placed on a dripping-pan and run into this would be equally heated by all-round converging radiation, and exquisitely roasted in the course of ten to thirty minutes, according to its size. Some such an apparatus has yet to be invented in order that we may learn the flavour and tenderness of a perfectly-roasted small joint of beef or mutton.

For roasting large masses of meat, a different proceeding is necessary. Here we have to contend, not with excessive surface in proportion to bulk—as in the grilling of chops and steaks, and the roasting of small joints—but with the contrary, viz. excessive bulk in proportion to surface. If a baron of beef were to be treated according to my prescription for a steak, or for a single small wing rib, or other joint of three to five pounds weight, it would be charred on its surface long before the heat could reach its centre.

A considerable time is here inevitably demanded. Of course, the higher the initial outside temperature, the more rapidly the heat will penetrate; but we cannot apply this law to a lump of meat as we may to a mass of iron. We may go on heating the outside of the iron to redness, but not so the meat. So long as the surface of the meat remains moist, we cannot raise it to a higher temperature than the boiling-point of the liquid that moistens it. Above this, charring commences. A little of such charring, such as occurs to the steak or small joint during the short period of its exposure to the great heat, does no harm; it simply ‘browns’ the surface; but if this were continued during the roasting of a large joint, a crust of positively black charcoal would be formed, with ruinous waste and general detriment.

As Rumford proved long ago, liquids are very bad conductors, and when their circulation is prevented by confinement between fibres, as in the meat, the rate at which heat will travel through the humid mass is very slow indeed. As few of my readers are likely to fully estimate the magnitude of this difficulty, I will state a fact that came under my own observation, and at the time surprised me.

About five-and-twenty years ago I was visiting a friend at Warwick during the ‘mop,’ or ‘statute fair’—the annual slave market of the county. In accordance with the old custom, an ox was roasted whole in the open public market-place. The spitting of the carcass and starting the cookery was a disgusting sight. We are accustomed to see the neatly-cut joints ordinarily brought to the kitchen; but the handling and impaling of the whole body of a huge beast by half a dozen rough men, while its stiffened limbs were stretching out from its trunk, presented the carnivorous character of our ordinary feeding very grossly indeed.

Nevertheless I watched the process, partook of some of its result, and found it good. The fire was lighted before midnight, the rotation of the beast on the horizontal spit began shortly after, and continued until the following midday, all this time being necessary for the raising of the inner parts of the flesh to the cooking temperature of about 180° Fahr.