Agriculture.

Poverty Bay Standard, Volume X, Issue 1115, 5 August 1882, Page 6 (Supplement)

Agriculture.

THE CHEMIST IN THE DAIRY.—No. 111. By R. W. Emerson Maclvor, F. I. C.,F. C. S.,&c. AUTHOR 01? “ THE CHEMISTRY OF AGRICULTURE.” Skim milk has the following average composition :— Water.. 90’0 Albumenoids .. .. ... 3-7 Fat .. o’B Sugar .. .. .. .-. 4’B Ash 0-7 100-0 Its specific gravity is higher than than that of fresh milk, ranging from 1-034 to 1-037-BUTTER. Batter consists mainly of a solid fat called palmitin, and a liquid fat olein. It also contains a small percentage of stearin, a solid fat occurring largely in suet. The characteristic properties of butter are due to the presence of certain other fats termed butyrin, caprin, caproin, and capryllin. Fats are known to be compound? of fatty acids, with glycerine, and are designated glycerides. When. heated with potash or soda, they are decomposed, or split up into soap and free glycerine. Soap is, simply fat in which the glycerine is replaced ’ by potash or soda. Stearic, palmitic, and oleic acids (the acids, which, in combination with glycerine, form stearin, palmitin, and olein, respectively), common to all ordinary fats, are neither volatile nor soluble in water; whereas butyric, caproic, caprylic, and capric acids (the acids of the peculiar fats butyrin, caproin, capryllin, and caprin respectively) are volatile at 500 degrees Fahrenheit, and are soluble in water. In pure butter, these latter amount to from 5 to 6 per cent., and the former to from 86 to 88 per cent. In suet, lard, and other meat-fats, there are no volatile fatty acids, and the fixed and insoluble fats amount to 85 per cent. The fact that butter contains about 6 per cent, of fatty acids, which are soluble in water when separated from the glycerine with which they are united, serves to distinguish it from other animal fats in which soluble fatty acids are absent. When butter becomes rancid, the volatile fatty acids are in part separated from the glycerine with which they are combined, and it is to this fact we attribute the bad flavor and smell of the butter. In combination w’ith glycerine, the volatile acids are odourless, but when released from the union they each possess distinct and marked peculiarities of smell and flavor. Butylic acid has a burning taste, and smells like a mixture of vinegar and stale butter; caproic acid has an odour resembling that of a goat—hence its name from capra, a goat; caprylic acid has a weaker but decidedly disagreeable smell; and capric acid is similar to caproic acid, having a very sour and burning taste. The combined qualities of these bodies are realised when we consume a small portion of rancid butter, milk or cheese. The solubility of these fatty acids in water indicates that the quality of stale butter may be much improved by washing it in warm water. As met with in commerce, butter contains from 7 to 20 per cent, [generally 10 to 14] of water; 70 to 87 per cent, [generally 76 to 85 j of fats; o*s to 4 per cent, [usually [o*s to l*2j of casein or curd ; and from o*s to 12 per cent, [generally 2 to 4] of salt. Buttcr-makiny : Churning has the effect of bringing about the union of the minute fat—globules which in milk and cream have existed, disseminated throughout the mass. The agitation to which the milk or cream is subjected bursts the alluminous covering or shell of the globules, and lets the fat free to coalesce in the form of lumps of butter. The advantage or otherwise of churning the whole milk, or only the cream, depends upon circumstances. A slightly increased quantity of butter is obtained by working the whole milk, but the process is more laborious than when cream alone is used, and changes all the milk, after the separation of the butter, into sour milk, at the loss of getting skimmed milk for making skim-milk cheese, or for domestic consumption. The ordinary practice is to make butter from cream alone. It is usual to permit the cream to become slightly acid before it is introduced into the churn. In this way the butter comes sooner, and much more freely. The souring must not, however, be allowed to go too far, as the butter obtained is certain to be inferior in quality. Some experienced men hold that the fresher the cream when used, the better is the flavor of the butter; whilst others contend that the slightly soured cream yields the firmest product.

The temperature at which the milk or cream is churned is of great importance. If it be too low, the butter will be slow in coming, and will possess a hard texture ; whereas, if it be too high, the product will be wanting in grain, greasy, and deficient in quantity. If is not possible to fix a temperature at which churning should always be carried, out. The proportion between the solid and the liquid fats in the milk is influenced to some extent by the diet of the cow, and this renders a change of temperature absolutely necessary. A somewhat higher temperature is necessary in winter than in summer, and also in the case of sour cream than in that of sweet cream. It is taken as a general rule that fresh cream should be put in the churn at 50 degrees to 55 degrees Fahrenheit, and sour cream at 52 degrees to 60 degrees. When sour milk is churned for butter, the temperature should not be less than 65 degrees. “ The precise temperature most suitable for churning,” says Warington, “ may be ascertained by recording every day the temperature employed, with the length of time occupied in churning, and the amount and character of the produce; when this is done the temperature for each day can be regulated from the experience of the preceding working. The temperature will rise several degrees during churning.”