CHAPTER V. COOLING MILK.
The management of milk, when once obtained, is the great practical consideration with the farmer and cheese-maker. But the first handling and care devolve upon the farmer; the cheese-maker's duties begin with the delivery of the milk at the factory. Much, very much, depends upon the treatment of the milk after milking, and the consequent condition in which it is delivered. We will therefore begin at the stable or yard and follow the milk through all its stages, until it is run into the weighing-can.
Previous suggestions as to cleanliness, etc., being adopted, we find the hot milk in the pails ready to be strained into the can standing on the platform or in the wagon. We say "strained," because this is necessary to absolute cleanliness, which affects the flavor, though at some factories the patrons are directed not to strain the milk, for the reason that poor care is so often taken of the strainer, and the keeping of the strainer drawn tight over the top of the can prevents cooling and hastens taint. For this reason, we would recommend the use of strainer-pails, unless the cloth strainer can be stretched above the can so as to allow the heat to escape and the cool air to come in. These precautions should be observed, most certainly, if no means is adopted for cooling the milk before starting for the factory.
The subject of cooling and airing milk has long been earnestly discussed, and the importance of cooling, at least, we believe is universally conceded. But how is this end to be attained, with the thermometer indicating an average temperature of 80°, and perhaps higher? The first and simplest suggestion is to set the can in a tub of cold water—cold spring or well-water, or iced water—and to give the milk frequent agitation with a dipper or other convenient article, care being taken to stir it from the bottom, as the cold milk naturally settles, and of course the hot milk lies on the top. Gentle agitation secures the advantage, also, of preventing the cream from rising. This makes trouble, and consumes a little time, but we believe the result will well repay both.
The milk-can should, by all means, be kept out of the sun's rays, and in a clean airy place. As to the importance of airing milk, there is a difference of opinion. Some assert that the airing is beneficial only so far as it assists in cooling, and that if we can succeed in cooling the milk down to 60°, or thereabouts, immediately after milking, we shall attain all the good results apparent from exposure to the air. All the "animal odors," they say, disappear. Be that as it may, it is scarcely possible to cool milk without more or less exposure to the atmosphere, and we have never heard it claimed that any bad consequences follow this exposure. It is possible, however, that it may more rapidly absorb oxygen, and thus sooner sour. The probability is, that any process which will secure the proper cooling will also afford the necessary exposure for the escape of all animal or other odors likely to pass off in the form of gas. Therefore, practically, it is of very little importance whether we consider the question of airing milk, in any of the stages of its management. So we will first look after the processes which secure known advantages.
Several inventions for the purpose of cooling milk have made their appearance within the past year or two. Some for the use of factories, which seem to work quite satisfactorily, and others for the use of farmers, none of which, we believe, have yet been received with much favor. They are mostly too complicated, if not too expensive, and too difficult to keep clean, to ever become generally adopted. Yet, enough has already been developed to convince us that the desideratum, of a satisfactory apparatus for cooling milk as fast as, or soon after, it is taken from the cow, can be realized. The great trouble is, to make farmers use it faithfully, if at all.
The cooling of milk as fast as milked, or very soon afterward, is the great question now presented to farmers and cheese-makers. It is of quite as much and more consequence, than keeping it cool at the factory—for milk is often so far advanced in decomposition, if not actually sour or tainted, when received, that it is impossible to work it up satisfactorily. Some Yankee must give us a simple and cheap apparatus that will effect the desired result. Such an invention will greatly improve the quality and increase the consumption and price of American cheese. But, in the absence of anything better, the can set in a tub of water and the milk frequently stirred, would be a great improvement on starting for the factory with hot milk. If the water can be made to constantly run into the tub, fresh and cool, as the warm water runs out, so much the better. Another improvement would be some kind of wagon-cover, permitting the air to pass under it, to keep off the sun in clear weather and keep out the rain in wet weather. The hot rays of the sun, pouring on a can of milk for the distance of two or three miles, perhaps—especially if the milk is not cooled before starting—cannot fail to do it serious injury. Milk thus exposed often has a very offensive smell when it reaches the factory-door. This shows that it is already tainted and in a condition to injure the good milk in the vat into which it is run, and cause a porous or "huffy" curd.
The question as to the effect of suddenly cooling milk has been somewhat discussed; also as to how low a temperature is beneficial. Experiments are necessary to definitely and satisfactorily settle these questions. Our impression is that, if ice is not used, there is no danger of cooling milk too suddenly or of getting it too cool. But where ice is used, especially if permitted to come in contact with the milk, or even to be separated from it only by a thickness of tin, there is danger of chilling the particles of milk in immediate contact with the cold surface, and causing them to prematurely decay. This would, of course, injure the keeping qualities of the rest of the batch. So far as the suddenness of the operation is concerned, we doubt if it would have any material effect, one way or the other. But where any portion of the milk is chilled, whether the whole batch of milk be slowly or suddenly reduced in temperature, we should expect it to injure the flavor and keeping qualities of the cheese. Some experiments, like the one made and related by Mr. Farrington, of Canada, at the last Convention of the American Dairymen's Association, would seem to favor the conclusion, that suddenly reducing the milk to a low temperature is unfavorable to the production of the best quality of cheese. More experiments, as we have previously suggested, are necessary to finally settle these questions. But of the importance of cooling milk down to as low a temperature as 60° to 65°, there can be no doubt; and there need be no fear of milk being cooled rapidly enough to injure it where only water is used in the process of cooling.