The Chemistry of Cookery

by W. Mattieu Williams

The first stage of this cookery of sugar has now an archæological interest in connection with one of the lost arts of the kitchen, viz. the ‘spinning’ of sugar. Within the reach of my own recollection no evening party could pretend to be stylish unless the supper-table was decorated with a specimen of this art—a temple, a pagoda, or something of the sort done in barley-sugar. These were made by raising the sugar to 320°, when it fused and became amorphous, or vitreous, as already described. The cook then dipped a skewer into it; the melted vitreous sugar adhered to this, and was drawn out as a thread, which speedily solidified by cooling. While in the act of solidification it was woven into the desired form, and the skilful artist did this with wonderful rapidity. I once witnessed with childish delight the spinning of a great work of art by the Duke of Cumberland’s French cook in St. James’s Palace. It was a ship in full sail, the sails of edible wafer, the hull a basketwork of spun sugar, the masts of massive sugar-sticks, and the rigging of delicate threads of the same. As nearly as I can remember, the whole was completed in about an hour.

But to return from high art below stairs to chemical science. The conversion of sugar into caramel is, as already stated, attended with a change of flavour; a kind of bitterness replaces the sweetness. This peculiar flavour, judiciously used, is a powerful adjunct to cookery, and one which is shamefully neglected in our ordinary English domestic kitchens. To test this, go to one of those Swiss restaurants originally instituted in this country by that enterprising Ticinese, the late Carlo Gatti, and which are now so numerous in London and our other large towns; call for maccheroni al sugo; notice the rich brown gravy, the ‘sugo.’ Many an English cook would use half a pound of gravy beef to produce the like; but the basis of this is a halfpennyworth or less of what I call a caramel compound, as an example of which I copy the following recipe from the Household Edition of Gouffé’s ‘Royal Cookery Book:’ ‘Melt half a pound of butter; add one pound of flour; mix well, and leave on a slow fire, stirring occasionally until it becomes of a light mahogany colour. When cool it may be kept in the larder ready for use.’ Gouffé calls this ‘Liaison au Roux;’ the English for liaison is a thickening. It is really fried flour. Burnt onion is another form of caramel, with a special flavour superadded. Plain sugar caramel is improved by the use of a little butter, as in making toffee. Thus prepared it is really a fried sugar rather than a baked sugar. Beurre noir (black butter) is another of the caramelised preparations used by continental cooks.

While engaged upon your macaroni, look around at the other dishes served to other customers. Instead of the pale slices of meat spread out in a little puddle of pale watery liquid, that are served in English restaurants of corresponding class, you will see dainty morsels, covered with rich brown gravy, or surrounded by vegetables immersed in the same. This ‘sugo’ is greatly varied according to the requirements, by additions of stock-broth, tarragon vinegar, ketchup, &c., but burnt flour, burnt sugar, or burnt onions, or burnt something is the basis of it all.

To further test the flavouring properties of browning, take some eels cut up as usual for stewing; divide into two portions; stew one brutally—by this I mean simply in a little water—serving them with this water as a pale gravy or juice. Let the second portion be well fried, fully caramelised or browned, then stewed, and served with brown gravy. Compare the result. Make a corresponding experiment with a beefsteak. Cut it in two portions; stew one brutally in plain water; fry the other, then stew it and serve brown.

Take a highly-baked loaf—better one that is black outside; scrape off the film of crust that is quite black, i.e. completely carbonised, and you will come to a rich brown layer, especially if you operate upon the bottom crust. Slice off a thin shaving of this and eat it critically. Mark its high flavour as compared with the comparatively insipid crumb of the same loaf, and note especially the resemblance between this flavour and that of the caramel from sugar, and that of the browned eels and browned steak. A delicate way of detecting the flavour due to the browning of bread is to make two bowls of bread and milk in the same manner, one with the crust the other with the crumb of the same loaf. I am not suggesting these as examples of better or worse flavour, but as evidence of the fact that much flavour of some sort is generated. It may be out of place, as I think it is, in the bread and milk, or it may be added with much advantage to other things, as it is by the cook who manipulates caramel and its analogues skilfully.

The largest constituent of bread is starch. Excluding water, it constitutes about three-fourths of the weight of good wheaten flour. Starch differs but little from sugar in composition. It is easily converted into sugar by simply heating it with a little sulphuric acid, and by other means, of which I shall have to speak more fully hereafter, when I come to the cookery of vegetables. When simply heated, it is converted into dextrin or ‘British gum,’ largely used as a substitute for gum arabic. If the heat is continued a change of colour takes place; it grows darker and darker, until it blackens just as sugar does, the final result being nearly the same. Water is driven off in both cases, but in carbonising sugar we start with more water, sugar being starch plus water or the elements of water. Thus the brown material of bread-crust or toast is nearly identical with sugar caramel.

I have often amused myself by watching what occurs when toast and water is prepared, and I recommend my readers to repeat the observation. Toast a small piece of bread to blackness, and then float it on water in a glass vessel. Leave the water at rest, and direct your attention to the under side of the floating toast. Little threadlike streams of brown liquid will be seen descending in the water. This is a solution of the substance which, if I mistake not, is a sort of caramel, and which ultimately tinges all the water.

Some years ago I commenced a course of experiments with this substance, but did not complete them. In case I should never do so, I will here communicate the results attained. I found that this starch caramel is a disinfectant, and that sugar caramel also has some disinfecting properties. I am not prepared to say that it is powerful enough to disinfect sewage, though at the time I had a narrow escape from the Great Seal Office, where I thought of patenting it for this purpose as a non-poisonous disinfectant that may be poured into rivers in any quantity without danger. Though it may not be powerful enough for this, it has an appreciable effect on water slightly tainted with decomposing organic matter.

This is a very curious fact. We do not know who invented toast and water, nor, so far as I can learn, has any theory of its use been expounded, yet there is extant a vague popular impression that the toast has some sort of wholesome effect on the water. I suspect that this must have been originally based on experience, probably on the experience of our forefathers or foremothers, living in country places where stagnant water was a common beverage, and various devices were adopted to render it potable.

Gelatin, fibrin, albumen, &c.—i.e. all the materials of animal food—as already shown, are composed, like starch and sugar, of carbon, hydrogen and oxygen, with, in the case of these animal substances, the addition of nitrogen; but this does not prevent their partial carbonisation (or ‘caramelising,’ if I may invent a name to express the action which stops short of blackening). Animal fat is a hydrocarbon which may be similarly browned, and, if I am right in my generalisation of all these browning processes, an important practical conclusion follows, viz. that cheap soluble caramel made by skilfully heating common sugar or flour is really, as well as apparently, as valuable an element in gravies, &c., as the far more expensive colouring matter of brown meat gravies, and that our English cooks should use it far more liberally than they usually do.