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THE PRINCIPLES OF BUTTER-MAKING
A SAMPLE of pure butter should contain no more than from 10 to 15 per cent. of moisture, a good sample averaging about per cent., and, unless heavily salted, an almost infinitesimal proportion of mineral matter. Theoretically, butter should contain nothing more than the fat of milk, the salt which is added during manufacture, and the water which up to a certain point is inseparable from butter. Those who understand the manufacture of butter are well aware that both by the exercise of skill and carelessness a much larger amount of water can be added to it than is essential; and it follows that the larger the amount of water, the greater the weight of the butter produced. To knowingly manufacture butter with excessive moisture is fraudulent, for the consumer pays the price of butter for water; but it should be remembered that the perpetrators of a fraud of this character often defeat their own object, inasmuch as butter of high quality cannot be produced, nor will it keep if the water is excessive. Excessive salting is equally deleterious to the quality; a minute proportion of salt improves the flavour common to butter, but a large quantity masks it, at the same time adding to the weight. We have remarked that there should be no other material in butter than fat, water, and salt. In practice, however, it is next to impossible to remove either the whole of the sugar, or the casein or curdy matter; and this being the case, in the course of time — and it depends entirely upon the proportion of caseous matter left in the butter — a sample becomes rancid and unfit either for sale or consumption. The prime object, therefore, under the British system of butter-making is to produce as large a quantity of butter of the finest flavour as possible, reducing the moisture and the extraneous curdy matter and sugar to the lowest possible proportions. In the first place, then, in order to produce quantity it is necessary to use the cream separator, which extracts more fat from the milk than is obtainable by any other process. If this is followed by treatment which has for its object the conversion of as much of this fat as possible into butter, a maximum quantity will be obtained. As regards quality, it is first of all important that the milk should be obtained from carefully fed cows which are milked by clean hands into clean vessels, the milk being subsequently strained before manipulation. The apartment in which the various operations take place should be perfectly pure. In this case the cream from the separator will in due course ripen properly, and fine flavour will in consequence develop. Having obtained quantity and flavour, we have next to deal with the conversion of the butter-fat obtained in the churn into made-up butter. As we shall see, the grains of fat as they are first produced are floating in buttermilk, the particular constituent of which is casein. This casein is an essential food of the lactic ferment; hence its removal is necessary. Careful washing, therefore, is the first process; and if the tiny grains are washed at a given stage, which is shown in every dairy school, the greater portion of the curd will be removed, and almost pure butterfat left behind.
Let us, however, assume that inferior butter is produced in a dairy, and that the occupier is unable to improve the quality. It may be asked how the production of an inferior article can be converted into the production of one of really high quality. The thing is easy if the work is carried out with intelligence and thoroughness. The manufacturer must condescend to details and recognize scientific facts. The alteration which takes place in cream, that is to say its change from perfect sweetness to a condition of sourness, acidity, or ripeness, is owing to the presence of an organism or bacterium which can only be discovered by those who are skilled in the use of the microscope. This organism rapidly increases in number when milk is warm and exposed to the atmosphere. It converts the sugar of milk into lactic acid; hence the sourness of milk. If this change is allowed to continue unchecked, the curd of the milk will coagulate, and it is for this reason that cream when allowed to ripen for churning becomes thicker. If cream is churned while it is still sweet it is frequently longer before it is converted into butter, it produces less butter, and the flavour is less full and nutty. The object, therefore, of ripening cream is to increase the quantity of butter and improve the flavour. In every dairy the lactic ferment is present either upon the utensils or in the atmosphere itself; but in some cases there are other organisms which, unlike the lactic ferment, have a contrary influence, producing a disagreeable flavour which reduces the value of the butter. The object of the dairyman, therefore, should be to maintain the apartment in which the milk or cream is placed, as well as the utensils employed, in as cleanly a condition as possible. There need be no fear about boiling water or lime destroying the lactic ferment. If it is removed from the utensils it is present in the air, and present, too, in a clean dairy perhaps in much larger numbers than any other organism is likely to be, and it is absolutely essential to the production of good butter. On the other hand, in a dirty apartment and on dirty utensils dangerous ferments are common; and if through conditions which suit them — and dirt is the chief of these — they are induced to increase in number, they may obtain the mastery, and destroy the flavour and quality of the butter produced. Let us suppose, therefore, as we have suggested already, that bad butter is produced in a dairy which has not been kept under the most perfect conditions. How can a change be brought about? In the first place, the whole of the utensils, shelves, and tables should be removed and thoroughly cleansed with boiling water. The walls and ceilings should be lime-washed and the floor scalded and dried, for a dairy should be dry. In this way every colony or nest, as it were, of the undesirable bacteria will be destroyed, and the clean utensils being returned to the dairy may be employed both in the raising of cream and in the manufacture of butter without any fear whatever. If, however, the manufacturer desires to proceed upon still more definite lines, and to omit no course of procedure which will ensure success, he may introduce from the most successful dairy with which he is acquainted a small quantity of the sour buttermilk which has been produced from the same day's churning. This buttermilk will contain the germs or bacteria which have been responsible for the production of butter-flavour of high class. If this buttermilk is added to the cream which has been obtained from the milk in the now thoroughly clean dairy, that cream will be inoculated, and when it has ripened it will be sufficiently perfect to be churned with every hope of success; and henceforth, so long as cleanliness is observed, there need be no fear as to the maintenance and constant reproduction of the friendly bacteria which are so desirable, as we have pointed out, in the manufacture of butter.
Let us now deal with the actual process of manufacture. The milk is drawn from the cows, and arrives in the dairy at a temperature of about 90° F. or a little higher. It may be at once passed through the mechanical separator and skimmed, or it may be poured while still warm into shallow vessels in order that the cream may rise by gravitation. Under such conditions the dairy should not be more than 60° F. — if it is as low as 50°, so much the better. The reason is that the greater the difference between the temperature of the milk and the temperature of the dairy the quicker and the more effectually will the cream rise. Cream is present in milk in the form of tiny globules; these globules are much lighter than the other portion of the milk, hence when the milk is at rest they rise to the surface just as a cork rises to the surface of a volume of water at the bottom of which it has been placed. The reason why the fat rises better in warm milk placed in a cold apartment is that the fat feels the change of temperature less rapidly than the rest of the milk, inasmuch as it is a non-conductor of heat. This being so, the difference in the density or specific gravity of the fat and the liquid portion of the milk is greater, and the fat is relatively lighter than it would otherwise be where there is no difference in the temperatures. In hot weather cream rises with far greater rapidity than in cold; milk rapidly becomes acid, both cream and milk thicken or coagulate, and for this reason the smaller globules of fat which are at the bottom of a milk-setting vessel are not able to rise at all — they are impeded, as it were, by the coagulation of the casein, hence a proportion of the butter-fat is lost to the churn. When, however, cream is raised upon a shallow vessel, it forms a thin layer on the surface and is brought into direct contact with the air, and consequently is oxidized or ripened with greater perfection: on the other hand, where cream is obtained through the medium of the separator it is kept in bulk and is less thoroughly oxidized, because in passing through the machine it has been in contact with the air for but a few seconds, while the air does not so thoroughly affect the mass of cream which is kept in a particular vessel as it does when the same cream is raised over a large area on the milk in a number of vessels. It is next to impossible to describe the exact flavour and appearance of cream which is just ripe for churning. Those who desire to know what it is like should take a lesson from an expert — and fortunately there are now plenty of teachers in almost every county in England.
When ripe the cream is passed through a strainer into the churn, and churned at a temperature which varies in accordance with the season of the year. In summer it may be churned at 56° F. and in winter as high as 64° F., but the exact degree depends upon the heat of the atmosphere, as we have suggested: a little experiment will enable the operator to thoroughly understand this point. Mixed cream should never be used: i. e. sweet and sour cream mixed together. The churn should be well cooled in summer and slightly warmed in winter by the aid of clean water, and let us remark that nothing is of greater importance than pure water; if it is impure, containing organic matter, this matter will be imported into the butter and will assist in decomposing it. After churning gently for a few minutes the carbonic acid gas which has formed in the churn may be allowed to escape by pressing the ventilator. Churning then continues until the grains of butter have reached the size of rice. At this point great care must be exercised. Some excellent makers here add a few quarts of very cold pure water, which gives crispness to the grains, preventing their adhering to each other so completely. The butter-milk is then drawn off through a sieve and more cold water added. It should be sufficient to enable the grains of butter to float in the churn and to partially harden. The water is then again drawn off and fresh cold water added two or three times, the churn being turned gently that the butter grains may be washed, although they should not unite and increase in size. Lastly, thin brine may be added, and in this the butter may remain for some little time before it is removed, or the floating butter may be removed from the brine with a scoop and placed upon the butter-table, or into the butter-drier or délaiteuse, from either of which the water is removed, by working in the one case, and by centrifugal force in the other. If dry salting is now performed the salt should be weighed, having previously been thoroughly rolled as fine as possible, dried in an oven and rolled again. It may be distributed by the aid of a dredger over the butter at the rate of half an ounce to the pound. If the butter is to be salted for keeping, from three-fourths of an ounce to an ounce may be used to the pound. The water having been perfectly expelled, the butter is made up for the market, or it may be allowed to remain in a wooden trough to still further drain, or it may, as in Denmark, be made up into rough rolls, allowed to harden for five or six hours, again worked, and finally made up for sale.