| cwts. | |
|---|---|
| To Great Britain | 441,226 |
| To foreign countries | 51,637 |
Of late years the exportation to foreign and colonial countries has fallen off; still the export trade is very considerable, probably amounting to 450,000 cwts. per annum. During the year 1867, the imports of foreign butter into Great Britain amounted to 1,142,262 cwts.
I have quoted the above statistics for the purpose of demonstrating the great importance of the butter trade to this country. Not only is a large proportion of the agricultural community pecuniarily interested in the production of this article, but the exportation is the chief cause of the commercial prosperity of a city, which, in point of population, ranks third in the kingdom. If butter, then, be an article of so much importance, it is obvious that the greatest care should be taken in its preparation, and that the efforts of both scientific and practical men should be directed towards the best mode of improving its quality. If the principles involved in the production of butter were thoroughly understood, and generally known, I believe that such terms as "seconds," "thirds," and "fourths," would speedily fall into disuse; that there would be only one kind of butter sent into the market; and that the article would always be of the best quality, in other words, "firsts."
Composition of Butter.—The composition and quality of butter depend to a great extent upon the condition of the milk or cream from which it is prepared, and on the skill and cleanliness of the dairy-maid. It consists essentially of fatty and oily matters, but it is always found in combination with casein (cheesy matter) and water. The following analyses, made by Mr. Way, late consulting chemist to the Royal Agricultural Society of England, shows its composition:—
| INGREDIENTS PER CENT. | |||
| 1. | 2. | 3. | |
|---|---|---|---|
| Fatty matters | 82·70 | 79·67 | 79·12 |
| Casein | 2·45 | 3·38 | 3·37 |
| Water | 14·85 | 16·95 | 17·51 |
No. 1 analysis shows the composition of a specimen obtained from the well-known Mr. Horsfall's dairy. It was made from raw cream. The other specimens were the produce of a Devonshire dairy, and were prepared from scalded cream. In several specimens of well-made and unsalted Irish butter which I have analysed, I found the proportion of casein or cheesy matter never to exceed 1 per cent., whilst in the analysis above stated the centesimal amount is on the average more than 3 per cent.
The fatty matter is composed of two substances—one, a solid, termed margarin; the other fluid, and styled by chemists elaine. The solid fat is identical in composition with the solid fat of the human body. The elaine is peculiar to milk, but it differs very slightly from olein, or fluid fat. The relative proportions of the fluid and solid fats vary with the seasons. According to Braconnot, the solid fat forms in summer 40 per cent. of the butter, but in winter the proportion rises to 65. This decrease in the proportion of the liquid fat in winter is the cause of the greater hardness of the butter in that season, which is often incorrectly attributed solely to the cold.
The cheesy and acid matters contained in butter are by no means essential; on the contrary, if it were quite free from them, it might be retained with little or no salt for a very long period without becoming rancid. The cheesy matter contains nitrogen; and nearly all the substances into which this element enters as a constituent are remarkably prone to decomposition. Yeast, and ferments of every kind—gunpowder, fulminating silver, chloride of nitrogen—and almost every explosive compound, contain this element. The cheesy matter is a very nitrogenous body, and in presence of air and moisture not only rapidly decomposes, or decays, itself, but induces by mere contact a like state of decomposition in other substances—such, for instance, as fat, sugar, and starch, which naturally have no tendency to change their state. Bearing the foregoing facts in mind, it is obvious that the chief precautions to be observed in the manufacture of butter are:—Firstly, to separate to as great an extent as practicable the casein from the butter; and, secondly, as in practice a small portion of the curd remains in the butter, to prevent it from undergoing any change—at least for a prolonged period. How these desiderata may best be accomplished I shall now proceed to point out.
The Butter Manufacture.—The theory of the process of churning is very simple. By violently agitating the milk or cream the little vesicles, or bags containing the butter, are broken, and, the fatty matter adhering, lumps of butter are formed. The operation of churning also introduces atmospheric air into the milk, which, aided by the high temperature to which the fluid is raised, converts a portion of the sweet sugar of milk into the sour lactic acid. By the alteration produced in this way in the composition of the milk, it is no longer capable of holding the casein in solution, and the curd therefore separates.
The churn and other vessels in which the milk is placed cannot be kept too clean. No amount of labor bestowed on the scalding and scrubbing of the vessels is excessive. When wood is the material used in the milk-pans the utmost care should be taken in cleaning them, as the porous nature of the material favors the retention of small quantities of the milk. A simple washing will not suffice to clean such vessels. They must be thoroughly scrubbed and afterwards well scalded with boiling water. Tin pans are preferable to wooden ones, as they are more easily cleaned, but in their turn they are inferior to glass vessels, which ought to supersede every other kind. Earthenware, lead, and zinc pans are in rather frequent use. The last-mentioned material is easily acted upon by the lactic acid of the sour milk, and is, therefore, objectionable. It is a matter of great importance that the dairy should not be situated near a pig-stye, sewer, or water-closet, the effluvia from which would be likely to taint the milk. It is surprising how small a quantity of putrescent matter is sufficient to taint a whole churn of milk; and as it has been demonstrated that the almost inappreciable emanations from a cesspool are capable of conferring a bad flavor on milk, it is in the highest degree important to remove from the churn and milk-pail every trace of the sour milk. I go further, it is even desirable that no one whose hands have a tendency to perspire should be allowed to manipulate in the dairy; and it should be constantly borne in mind that the dairy-maid's fingers and hot water should be on the most intimate visiting terms.