The Chemistry of Cookery

by W. Mattieu Williams

Returning to the subject of frying, we encounter a good illustration of the practical importance of sound theory. A great deal of fish and other kinds of food is badly and wastefully cooked in consequence of the prevalence of a false theory of frying. It is evident that many domestic cooks (not hotel or restaurant cooks) have a vague idea that the metal plate forming the bottom of the frying-pan should directly convey the heat of the fire to the fried substance, and that the bit of butter or lard or dripping put into the pan is used to prevent the fish from sticking to it or to add to the richness of the fish by smearing its surface.

The theory which I have propounded above is that the melted fat cooks by convection of heat, just as water does in the so-called boiling of meat. If this is correct, it is evident that the fish, &c., should be completely immersed in a bath of melted fat or oil, and that the turning over demanded by the greased-plate theory is unnecessary. Well educated cooks understand this distinctly, and use a deeper vessel than our common frying-pan, charge this with a quantity of fat sufficient to cover the fish, which is simply laid upon a wire support, or frying-basket and left in the hot fat until the browning of its surface, or of the flour or bread-crumbs with which it is coated indicates the sufficiency of the cookery. The illustration is from Gouffé’s excellent cookery-book already quoted, and is introduced because I have found it so little understood by English housewives. Frying-kettles may now be purchased at all our best English ironmongers, though until recently they were difficult to obtain. My lectures and papers have largely extended the demand and consequent supply.

Fig. 7.

At first sight the deep fat bath appears extravagant, as compared with the practice of greasing the bottom of the pan with a little dab of fat, but any housewife who will apply to the frying of sprats, herrings, &c., the method of quantitative inductive research, described and advocated by Lord Bacon in his ‘Novum Organum Scientiarum,’ may prove the contrary.

‘Must I read the “Novum Organum,” and buy another dictionary, in order to translate all this?’ she may exclaim in despair. ‘No!’ is my reply. This Baconian inductive method, to which we are indebted for all the triumphs of modern science, is nothing more nor less than the systematic and orderly application of common sense and definite measurement to practical questions. In this case it may be applied simply by frying a weighed quantity of any kind of fish or cutlet, &c., in a weighed quantity of fat used as a bath; then weighing the fat that remains and subtracting the latter weight from the first, to determine the quantity consumed. If the frying be properly performed, and this quantity compared with that which is consumed by the method of merely greasing the pan-bottom, the bath frying will be proved to be the more economical as well as the more efficient method.

The reason of this is simply that much or all of the fat is burnt and wasted when only a thin film is spread on the bottom of the pan, while no such waste occurs when the bath of fat is properly used. The temperature at which the dissociation of fat commences is below that required for delicately browning the surface of the fish itself, or of the flour or bread-crumbs, and therefore no fat is burnt away from the bath, as it is by the over-heated portions of a merely greased frying-pan; and as regards the quantity adhering to the fish itself, this may be reduced to a minimum by withdrawing it from the bath when the whole is uniformly at the maximum cooking temperature, and allowing the fluid fat to drain off at once. It may be supposed that by complete immersion of the fish in the fat-bath, more fat will soak into it, but such is not the case; the water amidst the fibres of the fish is boiling and driving out steam so rapidly that no fat can enter if the heat is well maintained to the last moment, and the frying not continued too long. When cooked on the greased plate, one side is necessarily cooling, and the fat settling down into the fish to occupy the pores left vacuous by the condensing steam, while the other is being heated from below.

The temperature of the fat-bath may be tested by the ordinary cook’s method—that of throwing into it a small piece of bread-crumb about the size of a nut. If it frizzles and produces large bubbles of steam, the full temperature of frying in the hottest of fat is reached; if it frizzles slightly, and only gives out small steam-bubbles, you have the temperature demanded for slow frying.

The bath-frying demands separate supplies of fat[9]—one for fish, another for cutlets and other similar kinds of meat, a third for such goody-goodies as apple-fritters—a most wholesome and delicious dish, too rarely seen on English tables. I suspect that the prevalence of the greased frying-pan is the reason of its rarity. Cooked by this barbaric device, apples are scarcely eatable, but when thin slices are immersed in a bath of melted fat at a temperature of about 300° Fahr., the water of their juice is suddenly boiled, and as this water is contained in a multitude of little bladderlike cells, they burst, and the whole structure is puffed out to a most delicate lightness, far more suitable for following solid meats than soddened fruit enveloped in heavy indigestible pudding-paste. Another advantage is that with proper apparatus (wire basket, kettle, and store of special fat) the fritters can be prepared and cooked in about one-tenth of the time demanded for the preparation and cookery of an apple pudding or pie. A few seconds of immersion in the fat-bath is sufficient.